STATE OF CALIFORNIA by shuifanglj

VIEWS: 15 PAGES: 39

									       STATE OF CALIFORNIA
       DEPARTMENT of TRANSPORTATION


               DIVISION OF
          ENGINEERING SERVICES

          MATERIALS ENGINEERING
           AND TESTING SERVICES

          OFFICE OF RIGID PAVEMENT
          AND STRUCTURAL CONCRETE

               5900 Folsom Boulevard
            Sacramento, California 95819




THE EFFECTIVENESS OF DIAMOND GRINDING
  CONCRETE PAVEMENTS IN CALIFORNIA

                     May 2005
   REPORT ON THE EFFECTIVENESS OF DIAMOND
  GRINDING CONCRETE PAVEMENTS IN CALIFORNIA
This report does not constitute a standard, specification, or regulation. The Caltrans
Office of Rigid Pavement and Structural Concrete and their consultants, Applied
Research Associates, Inc., are responsible for the accuracy of the information and data
presented in this report.

Report Prepared by...…….……………………                   ………………………Richard Stubstad
                                                             Michael Darter
                                                                Chetana Rao
                                                                   Tom Pyle
                                                                Walid Tabet




                                     __________________________________________
                                     RICHARD N. STUBSTAD, P.E.
                                     Principal Engineer
                                     Applied Research Associates – ERES Division




________________________________________
TOM PYLE, Chief
Office of Rigid Pavement and Structural Concrete
Materials Engineering and Testing Services




                                                                                          i
                                ACKNOWLEDGEMENTS

The Office of Rigid Pavement and Structural Concrete would like to express their
gratitude to the following for their participation, assistance, and support:


APPLIED RESEARCH ASSOCIATES, INC. – ERES CONSULTANTS DIVISION

                                     Ventura, CA Office
                                    Sacramento, CA Office
                                    Champaign, IL Office


                                      HEADQUARTERS

                        Materials Engineering and Testing Services
                                        District 4
                                        District 5
                                        District 6
                                        District 7
                                        District 8
                                       District 11
                                       District 12

         OFFICE OF ROADWAY REHABILITATION, DEPARTMENT OF
                          MAINTENANCE

                         Caltrans Headquarters – Sacramento, CA

                       WESTERN STATES CHAPTER –
                AMERICAN CONCRETE PAVEMENT ASSOCIATION

                                      Newport Beach, CA




Cover Photo: Courtesy of Western States Chapter – American Concrete Paving Association




ii
                                         TABLE OF CONTENTS


EXECUTIVE SUMMARY .................................................................................................... 1

INTRODUCTION.................................................................................................................. 3

EXPERIENCE OF OTHER STATES................................................................................ 3

THE CALTRANS PMS DATABASE.................................................................................. 5

RIDE SCORE IMPROVEMENT DUE TO GRINDING ............................................. 8

LONGEVITY OF CALIFORNIA GRINDING PROJECTS ....................................... 9

OTHER BENEFITS OF DIAMOND GRINDING ..................................................... 12

CRITERIA FOR USING GRINDING AS A REHABILITATION

TECHNIQUE ........................................................................................................................ 14


APPENDIX A ………..…………………….…..………..………………….. 17-32


POINTS OF CONTACT ....................................................................................BACK PAGE




                                                                                                                                 iii
                                                      LIST OF FIGURES

FIGURE 1 – SURVIVAL CURVES FOR 76 NATIONWIDE DIAMOND GROUND PAVEMENTS ............................... 4
FIGURE 2 – MEASURED IRI VALUES AFTER GRINDING A SECTION OF I-710 IN 1997 .................................. 6
FIGURE 3 – MEASURED IRI VALUES BEFORE AND AFTER GRINDING A SECTION OF I-5 IN 2000................. 7
FIGURE 4 – IMPROVEMENT IN RIDE QUALITY DUE TO DIAMOND GRINDING FROM 26 CALIFORNIA
              PROJECTS ...................................................................................................................................   8
FIGURE 5 – CHANGE IN THE RATIO OF IRI OVER TIME AS A FUNCTION OF THE INITIAL IRI AFTER
              GRINDING .................................................................................................................................   10
FIGURE 6 – RELIABILITY LEVELS FOR THE EXPECTED SURVIVABILITY OF CALIFORNIA DIAMOND
              GRINDING PROJECTS ................................................................................................................           11




                                                       LIST OF TABLES

TABLE 1 – TYPICAL NOISE LEVELS OF ARIZONA PCCP ............................................................................ 12
TABLE 2 – CPX TEST RESULTS FOR VARIOUS DIAMOND GROUND SURFACES (DBA)................................. 13
TABLE 3 – FRICTION VALUES AND PERCENT CHANGES DUE TO DIAMOND GRINDING ............................... 14




iv
EXECUTIVE SUMMARY

Diamond grinding has been used in California since 1965 to provide a smooth surface on
old Portland Cement Concrete (PCC) pavement. Given the large amount of PCC
pavement needing rehabilitation today, increased knowledge of its effectiveness is very
much needed. The present study is intended to better quantify the expected longevity or
“survival” of a diamond ground PCC pavement, and its overall effectiveness under
California conditions and construction practices.
Nationwide, studies have shown that the average longevity of a diamond ground project
is around 14 years, or about 11 years at an 80% certainty (reliability) level. The 76 test
sections involved in a recent nationwide study included freeze-thaw zones and other
adverse conditions not normally encountered in California. It was expected that the dry-
no freeze zone of California would yield even better results, due to the milder climate.
For the present study, data were obtained from several projects on the performance of
diamond grinding in California. Based on this historical data, Figure ES-1, below, shows
the average expected longevity of diamond ground projects in California, along with the
corresponding curves for the 70th, 80th and 90th percentile reliability levels.


                                                        2.5
    Percent increase in IRI as a ratio to initial IRI




                                                        2.0




                                                        1.5



                                                                                                                    Average statewide longevity of
                                                        1.0
                                                                                                                    diamond grinding = 16.8 years @
                                                                                                                    average percent increase in IRI of
                                                                      IRI means [standard deviations]               78% (ratio = 1.78).
                                                                      Average IRI ratio at rehab or regrind
                                                        0.5           IRI @ 70% reliability
                                                                      IRI @ 80% reliability
                                                                      IRI @ 90% reliability
                                                                      Expon. (IRI means [standard deviations])
                                                        0.0
                                                              0   2      4        6        8         10        12          14         16         18
                                                                                  Time after grinding, years


  Figure ES-1 – Expected survivability of diamond ground PCC pavements in
                                 California



                                                                                                                                                         1
In the preceding figure, the expected percent increase in the International Roughness
Index (IRI) is expressed as the average IRI for 26 statewide diamond ground projects
within one year after grinding divided into the average expected IRI for the same 26
projects at the end of their design lives using a 78% increase over this entire period of
time. In other words, if the IRI just after grinding on any given project is, say, 100 in/mi,
then (on average) it is expected to be 178 in/mi at the end of its design life when further
rehabilitation is likely to be applied. This second rehabilitation may be another grinding
project (up to three successive grinds have been performed on Route 10 in San
Bernardino County) or any other form of rehabilitation.
The upshot of Figure ES-1 is that, on average, a diamond ground PCC pavement should
maintain its smoothness for between 16 and 17 years in California, or better than 14 years
if, for example, an 80th percentile reliability level is applied. Compared to the correspond-
ing national average values of 14 and 11 years, respectively, these results are quite
reasonable, since the climatic conditions in California are comparatively favorable for
longer lasting PCC pavement performance.
The above results have been achieved by Caltrans without a formal project selection and
design procedure for a grinding project. Currently, there are no objective criteria (such as
maximum joint faulting, maximum percent cracked slabs, or a maximum roughness
value) that could be used as a trigger for the selection of any given concrete pavement as
a candidate for diamond grinding. Nevertheless, many factors are currently considered
and the process is working reasonably well, especially considering the excellent results
obtained to-date.
Currently, the specification for pavement smoothness after grinding is based on a
California Profilograph measurement using California Test Method #526, which is not
particularly stringent. Even though it is certainly possible for contractors to achieve a
very smooth surface as a result of grinding (combined with slab leveling for major
settlements or properly constructed dowel bar retrofits, if needed), this capability has not
yet been utilized to its fullest.
Two other major advantages to diamond grinding are also achieved: improved texturing
and skid resistance, and reduced tire/pavement interface noise levels. Based on current
experience, it is possible to diamond grind candidate concrete pavements up to three
times before major reconstruction is needed. This could extend the service life of a new
concrete pavement to, say, twice its normal design life by adding only these two or three
diamond grinding projects and continuing normal routine maintenance—none of which
should disrupt the traffic flow during “peak” hours.




2
THE EFFECTIVENESS OF DIAMOND GRINDING
       CONCRETE PAVEMENTS IN CALIFORNIA

INTRODUCTION

With the rising costs of both pavement construction and user delays during construction
or rehabilitation, more attention is being given to effective and simpler measures of
pavement rehabilitation that can be carried out on our California freeway system while
minimizing the impact of rehabilitation on road users. One rehabilitation alternative that
is now commanding nationwide attention on concrete pavements is diamond grinding. In
fact, the technique was first used in 1965 on a 19-year old section of I-10 in Southern
California to eliminate excessive faulting. This pavement was again ground in 1984 and
again in 1997 and is still amazingly carrying heavy traffic today—nearly 60 years after it
was first constructed!
Through diamond grinding, it is possible to extend the service life of many of our aging
concrete pavements at a relatively low cost and with minimal disruption to traffic flow. In
the past, many states have employed diamond grinding as a viable rehabilitation
technique with excellent results. The question is: Exactly how effective is diamond
grinding, as opposed to other rehabilitation alternatives, and how much does it cost
relative to other alternatives?
In this report, it will be shown that diamond grinding is in fact a viable and cost-effective
rehabilitation measure when properly applied. Diamond grinding not only extends the
service life of a concrete pavement, but it also reduces tire-pavement interface noise and
improves texture and skid resistance. Because the pavement is much smoother after
grinding, highway user costs are also reduced through improved fuel efficiency and lower
vehicle maintenance costs.

EXPERIENCE OF OTHER STATES

A 1999 TRB paper by Rao, Yu, Khazanovich and Darter entitled “Longevity of Diamond
Ground Concrete Pavements” is a thorough study on many nationwide grinding projects
available through 1999. This study can be summarized as follows:
  1)     The study included 76 projects from 9 states, including California and Arizona
         but also including pavements in the more hostile climatic zones, such a freeze-
         thaw areas where PCC material durability issues may have contributed to a
         shorter life cycle.
  2)     The performance of diamond ground PCC pavements differed somewhat,
         depending on the amount of CPR performed (e.g., dowel retrofit, slab repairs)
         and the extent of structural and environmental damage prior to grinding.
  3)     50% of the study’s diamond ground sections lasted some 14 years or more prior
         to a second regrinding or other rehab. These sections carried 13.5 million heavy
         axles (ESALs) on average. Similarly, 80% of the sections lasted at least 11


                                                                                           3
           years. Twenty-one percent of the projects carried more than 20 million ESALs.
           Accordingly, the performance of diamond ground sections located in the dry-no
           freeze zone of California is better than the nationwide findings indicate.
    4)     Some PCC pavements have been reground up to three times without a
           significant loss in structural integrity (one of these being the I-10 in Southern
           California). Many of these pavements are fairly thin by today’s standards, less
           than 250-mm (10-in). Thicker slabs—especially with dowels—should perform
           even better after regrinding.
    5)     In all cases, the texture and skid resistance of ground PCC surfaces improves
           considerably, followed by a gradual decline over the succeeding 8-15 years of
           longevity after a grinding project is carried out, depending on the hardness of
           the aggregate and spacing of the saw blades.
    6)     Noise characteristics were not measured or considered in the nationwide study.
Survival curves for the 76 test sections included in the nationwide diamond grinding
study report are reproduced in Figure 1.




         Figure 1 – Survival curves for 76 nationwide diamond ground pavements

Note that the left-hand curve represents the length of time a diamond ground pavement
lasted until regrind or other rehabilitation was needed, in terms of probability of failure.
In other words, since 50% of the study sections lasted 14 years or more, then the
nationwide average longevity of any arbitrary diamond ground section is approximately
14 years. Similarly, if one would like to know the design life of a diamond ground section
at a 90% probability of survival, then this value is read across the Y-axis at a probability
of failure of 10%, thus arriving at a 10-year design life.



4
It is also interesting to note from Figure 1 that the nationwide average life of a newly
constructed concrete pavement to rehabilitation or reconstruction (with one intermediate
grinding project) is between 35 and 40 years, an excellent track record that is exceeded
by over three-quarters of California’s rigid pavements.
To confirm the above nationwide findings and adjust these findings to California
conditions specifically, a review of the Caltrans Pavement Management System database
was carried out.

THE CALTRANS PMS DATABASE

A list of most of the recorded diamond ground sections statewide, meaning those
associated with and included in the current Caltrans PMS database, was obtained from
the Office of Pavement Management at Caltrans Headquarters in Sacramento. This
database primarily consists of concrete sections ground after 1997. In addition, a handful
of older diamond ground sections were also included. The Office of Pavement
Management identified more than 60 diamond ground sections statewide in California.
From the provided list, 30 sections were selected for further analysis, mainly based on the
apparent use in these cases of diamond grinding as the primary rehabilitation technique,
with only minimal (secondary) CPR activities or adjacent asphalt overlays, etc., in some
areas. This was done in order to focus the present study on the effect of diamond grinding
as a primary rehabilitation option when it is not used in combination with other
rehabilitation techniques in the same project.
The object was to determine, if possible, how much joint (step) faulting or other
measured distresses triggered the action of diamond grinding. However, the Caltrans
PMS does not track joint faulting specifically. Rather, it only mentions faulting as a “seat
of the pants” noticeable defect as the smoothness survey vehicle is driving over a section.
Accordingly, if faulting is mentioned as a distress, its magnitude is unknown.
On the other hand, the International Roughness Index (IRI) has been carefully monitored
by Caltrans since 1998 using a high-speed profiler. Since faulting will strongly affect a
section’s IRI, this parameter can be used as a surrogate to ascertain the short- and long-
term effects of diamond grinding.
An example of a diamond ground section along the I-710 freeway in District 7, Los
Angeles County, is shown in Figure 2.




                                                                                           5
                                IRI vs. Date After Grinding - Section 07-16950
                    R3-15.2                   I-710 MP 13.3-21.9
                    R3-17.9
        250
                    R4-17.9                                             y = 0.0197x - 588.15
                    L3-20.3                                                  R2 = 0.771

                    L4-20.3
        200
                    L3-21.3
                    L4-21.3
                    Average
        150         Linear (Average)
                                                           1



        100




         50
                     Diamond grinding com-
                     pleted by M ay 1997


          0
         5/20/ 97             10/2/ 98        2/14/00                   6/ 28/ 01              11/10/02
                                              D at e o f IR I Sur vey



      Figure 2 – Measured IRI values after grinding a section of I-710 in 1997

This section—Caltrans Project Number 07-16950 shown in Figure 2—was diamond
ground in May of 1997 (lanes and starting mileposts noted in the legend). The reported
date of completion is indicated by the left-hand date, which forms the Y-axis. No direct
IRI values were available prior to this date. However, for several of the approx. 1-mile
lane segments of Project No. 07-16950, IRI values were available for 5 consecutive years
(except 1998 when no IRI data were present in the database).
Although there is obviously a great deal of scatter shown along the individual lane-
segments shown in the figure, the overall IRI for this project has not changed much
during the reported five years of profile measurements. On average, in 1999 the IRI was
approximately 130 in/mi, while in 2003 it was evidently around 150 in/mi. If one
extrapolates back to the year of grinding, the after-ground average IRI was likely between
110 and 120 in/mi, depending on whether a linear or exponential extrapolation function is
utilized.
In other words, through extrapolation and using a terminal IRI of, say, 200 in/mi, this
section should survive a total of some 11-13 years from the date of grinding before
requiring further grinding or other rehabilitation. It should be added as well that this
section is under very high traffic loadings.
Another extremely high-trafficked diamond ground section of freeway from the I-5 in
District 7, also in Los Angeles County, is shown in Figure 3.




6
                                             IRI Tracking - Before & After Grinding - Section 07-17530
                                                                I-5 NB: MP 73.6-88.6


                         250
                                                                                                R4-76.5
                                                                                                R4-77.5
                                                                                                R4-78.5
                                                                                                R3-82.5
                         200
                                                                                                R3-83.5
                                                                                                Average
      IRI, inches/mile




                         150




                         100
                                              Diamond grinding com-
                                              pleted by April 2000


                         50




                           0
                          7/24/98   2/9/99    8/28/99     3/15/00     10/1/00   4/19/01    11/5/01   5/24/02 12/10/02 6/28/03
                                                                      Date of IRI Survey


  Figure 3 – Measured IRI values before and after grinding a section of I-5 in 2000

In the case of Section 07-17530 as shown in Figure 3, since the pavement was ground
around April of 2000, it was possible to ascertain both the before and after IRI levels for
some of the approximately 1-mile lane segments that were involved in the grinding
project (lanes and starting mileposts noted in the legend).
The average pre-grind IRI was evidently around 190 in/mi. After grinding, the average
IRI was reduced to about 120 in/mi, which has in turn increased through 2003 to around
140 in/mi, with a leveling trend possibly indicated over the past 2-3 years. If a “terminal”
IRI of 180-200 in/mi before any further major rehab is assumed, this section may well
survive some 10 years or more, depending on how joint faulting and slab cracking
develop which may cause the IRI-values to increase as time passes.
The above examples are but two of the 30 statewide diamond grinding projects analyzed,
26 of which were usable for a further regression analysis of the effect of diamond
grinding in California. Graphs of all 30 individual projects are included in Appendix A.
Based on all sections analyzed, it would appear that most of Caltrans’ diamond ground
sections have an acceptable but not an excellent level of smoothness after grinding,
expressed in IRI smoothness units using the Caltrans high-speed profiler. In general, one
would hope that diamond grinding would typically result in IRI values less than 100
in/mi. Some long wavelength profile settlements or heaves are impossible to remove
through grinding such a thin layer from the surface of the PCC. This level is dependent in


                                                                                                                                7
part on any major settlements or heaves that may exist along the project and to what
extent they are leveled out using slab leveling or other techniques. It is also possible that
one high-speed profiler will not exactly match another manufacturer’s device, for
example due to laser spot size or longitudinal sampling distance.
The two above examples indicate an initial IRI of somewhat over 100 in/mi, which is
certainly acceptable—especially if the rate of increase in IRI post-grinding is slow and
gradual. The average statewide post-grind IRI was 94 in/mi, while the average pre-grind
IRI was 165 in/mi.

RIDE SCORE IMPROVEMENT DUE TO GRINDING

All IRI data from the selected grinding projects were downloaded from the Caltrans PMS
database and put into spreadsheet format for further analysis. Two essential quantities
were sought: What is the average improvement in IRI due to any given project, and what
is the expected life cycle (number of years to next rehabilitation) of any given grinding
project?
The average improvement in IRI due to diamond grinding can be quantified as the ratio
between the average pre-grind IRI and the average post-grind IRI. Figure 4 shows the
ratio of pre-grind IRI to post-grind IRI as a function of IRI prior to grinding based on 26
statewide projects where both pre- and post-grind IRIs were available.


                                                       Improvement in Smoothness Due to Diamond Grinding: pregrind/postgrind IRI


                                           2.80

                                           2.60
    Before-grind / after-grind IRI Ratio




                                           2.40

                                           2.20

                                           2.00

                                           1.80

                                           1.60

                                           1.40
                                                                                                                  IRI Ratio
                                           1.20                                                                   Linear (IRI Ratio)

                                           1.00
                                                  50              100             150              200            250                  300
                                                                            IRI Before Grinding (inches/mile)


Figure 4 – Improvement in ride quality due to diamond grinding from 26 California
                                     projects


8
In Figure 4 it can be seen that there is a tendency for the pre- vs. post-grind IRI ratio to
increase as a function of the magnitude of the pre-grind IRI. In other words, if there is an
exceptionally rough, and most likely faulted, JCP pavement, the immediate improvement
through grinding tends to be greater than if the pre-grind IRI is relatively smooth and,
probably, less faulted.
However it can also be seen from Figure 4 that there is a great deal of scatter in the data,
indicating that the improvement in IRI through grinding may well be a function of the
quality of the work carried out by the grinding contractor or other site-specific factors
such as excessive foundation settlements or heaves from swelling soils. In fact, the
correlation R-squared for the best-fit line in Figure 4 is only 0.26. It was therefore
deemed more appropriate to work with an average improvement in terms of IRI when
evaluating the overall effectiveness of JCP grinding in California. The average pre- vs.
post-grind IRI ratio for these 26 projects was 1.78, which was also used in the overall
survival analysis as outlined in the following sections.

LONGEVITY OF CALIFORNIA GRINDING PROJECTS

Compared to the national average of 14 years (see Figure 1), the important question for
Caltrans is: How long is the average grinding project expected to last (i.e. until further
rehabilitation is needed) in California specifically?
Using all available data, the average improvement in IRI from the year of grinding
onwards was calculated for the entire database. Although most of the data were from
projects carried out within the last five years, a few projects (5 out of 26) were older,
ranging up to a project carried out 12½ years ago. The improvement in IRI for the year of
grinding was assumed to be 1, of course (no change in IRI was assumed for the year the
grinding project was carried out), followed by a gradual increase in IRI through
subsequent years.
A plot of these data, showing both a linear and an exponential regression curve, is shown
in Figure 5.
The IRI before a grinding operation was calculated based on the ratio of the average IRI
prior to the first grind divided by the average IRI after grinding. These results showed
that the average IRI just prior to grinding was 1.7835 times the IRI soon after grinding.
For lack of a better terminal criterion to indicate when further rehabilitation will be
needed, it was assumed that the average IRI before the next rehabilitation (including a
grinding option, if applicable) would be approximately the same as the IRI was before the
previous rehabilitation (which was diamond grinding for all examples used in the
analysis).




                                                                                               9
                                                       Regression Equations for All IRI Data from California
                                             2.5

                                                              IRI means                                  y = e0.0345x
                                                              Expon. (IRI means)                        R2 = 0.9189
  IRI ratio after initial grinding project




                                             2.0
                                                              Linear (IRI means)


                                             1.5
                                                                                                           y = 0.0416x + 1
                                                                                                               2
                                                                                                             R = 0.8898
                                             1.0

                                                                                                  Based on exponential
                                             0.5                                                  equation, x=16.8 years
                                                                                                  when y = 1.7835


                                             0.0
                                                   0                 5                  10                  15               20
                                                               Number of years after grinding project was carried out



 Figure 5 – Change in the ratio of IRI over time as a function of the initial IRI after
                                      grinding

Figure 5 reveals that the trend of the increase in IRI is probably exponential as opposed to
linear based on the R-squared values of both regressions (0.92 for exponential and 0.89
for linear). The most conservative of the two regression equations shown in Figure 5 is
the exponential relationship, where the average diamond ground PCC pavement in
California will last 16.8 years (i.e. when the IRI ratio equals 1.7835). This criteria utilizes
the average percentage change in IRI due to grinding as an ad-hoc, “terminal” increase in
IRI until further rehabilitation is needed after first grind.
If one instead had used the linear regression shown in Figure 5, the expected life of the
average California diamond ground project would increase to nearly 19 years. While this
is possible, it is unlikely that the rate of increase in IRI towards the end of the life of a
diamond ground project would be the same as it was towards the beginning of its design
life, as a linear extrapolation would indicate.
Therefore, to be conservative, a statewide average design life of 16 to 17 years should be
used, assuming Caltrans continues to use the same criteria to “trigger” an actual grinding
project as previously. It is to be noted that the data available for the analysis only spanned
over 12½ years and therefore includes an extrapolation of the model beyond the data
range to predict the number of years to achieve an average terminal IRI ratio of 1.78.



10
Another important consideration is: What certainty or reliability levels are associated
with the above 16.8-year average life cycle prediction?
Since the data primarily consisted of relatively recent projects, it was not possible to
calculate reliable standard deviations or coefficients of variation for all seventeen years of
average expected pavement life. In the event, only 12 years of annual data were available,
with the greatest number of observations occurring during the first four or five years after
grinding.
Accordingly, it was assumed that the weighted average standard deviation (weighted by
the number of observations for any given year after grinding) was valid as an overall
average standard deviation. The influence of the standard deviation in the confidence
level of the prediction was incorporated by means of a reliability factor. Suitable
adjustments are made to the mean predicted IRI ratio, i.e. the IRI ratios are “inflated” to
correspond to the predictions at different reliability levels. This adjustment at different
ages is based on the weighted average standard deviation.
Four different design life curves are shown in Figure 6, representing the average life of
ground JCP pavements as was shown in Figure 5, along with the 70th, 80th, and 90th
percentile reliability levels associated with a wide variety of California statewide
projects.

                                                2.5

                                                                                                       0.0345x
                                                                                                  y=e
                                                                                                   2
                                                                                                  R = 0.9189
                                                2.0
    Increase in IRI as a ratio of initial IRI




                                                1.5




                                                                                                           Average statewide longevity of
                                                1.0
                                                                                                           diamond grinding = 16.8 years @
                                                                                                           average IRI ratio of 1.78.
                                                              IRI means [standard deviations]
                                                              Average IRI ratio at rehab or regrind
                                                0.5           IRI @ 70% reliability
                                                              IRI @ 80% reliability
                                                              IRI @ 90% reliability
                                                              Expon. (IRI means [standard deviations])
                                                0.0
                                                      0   2      4        6         8        10         12        14        16        18
                                                                          Time after grinding, years


  Figure 6 – Reliability levels for the expected survivability of California diamond
                                    grinding projects




                                                                                                                                             11
Figure 6 reveals that even at a very conservative certainty level of 90% (meaning 9 out of
10 diamond grinding projects should last at least that long), the design life in California is
expected to be around 13½ years. This figure is nearly the same as the national average of
14 years, which is by definition based on a 50% certainty level.
Please note however that the analysis conducted did not consider the many other effects
that may confound the accumulation of pavement roughness. For example, traffic load
(very high in most of the projects selected), extent of faulting, slab cracking, soil type,
drainage, properly placed dowel bars, and workmanship (the overall quality of grinding
project) were not considered as independent causal factors. Due to the lack of data and
the limited number of projects available for analysis, it was not possible to consider more
than one indicator (IRI) to arrive at the above conclusions. Accordingly, the results of this
study represent an overall picture of many causal factors.

OTHER BENEFITS OF DIAMOND GRINDING

In the foregoing, it was shown that diamond grinding of jointed PCC pavement results in
a long service life in California when it is properly applied under the right conditions.
The actual lifespan of such a project is expected to compare well with most other
rehabilitation options, probably better than most. From a cost standpoint, the cost of
diamond grinding is typically about one-half that of a conventional HMA overlay. Thus,
when applied under appropriate existing pavement conditions (e.g., no highly progressive
structural cracking), diamond grinding is a very cost-effective rehabilitation technique for
PCC pavements in California.
There are two other potential benefits to diamond grinding that were not measured or
recorded in the Caltrans PMS database. One of these benefits is to achieve an appreciable
noise reduction in tire-pavement interface sound emissions, while the other is to improve
the safety of the freeway by virtue of an immediate and long-lasting increase in the skid
resistance of a diamond ground concrete surface.
It is commonly experienced that diamond ground pavements are much quieter after
grinding than before grinding. To quantify this well-known phenomenon, the Arizona
DOT (ADOT) ran a series of grinding and texturing tests along the SR-202 Freeway in
the Phoenix area. The test areas, with the grinder using differing blade spacings and
grinder configurations for several adjacent test areas, were called “whisper grind”
sections, since the primary objective of ADOT’s study was not smoothness but rather
noise mitigation. A summary table from ADOT’s Construction Report, “SR202 PCCP
Whisper Grinding Test Sections” (Scofield, October 2003) is reproduced in Table 1.

                    Table 1 – Typical noise levels of Arizona PCCP
         Surface Texture Type                     CPX Noise Level Measured at Tire (dBA)
Whisper Grind Test Section – Test Area #4                  95.5 (As-Constructed)
ADOT Uniform Longitudinal Tined (3/4”)                              99.1
ADOT Uniform Transverse Tined (3/4”)                               102.5




12
As can be seen in Table 1, compared to other common PCCP surface textures of
transverse tined or longitudinal tined, diamond ground surfaces are considerably quieter.
For new construction, Caltrans typically utilizes uniform longitudinal tining—which
tested out in Arizona at around 99 dBA using the close proximity method (CPX) of noise
measurement. As can be seen, considerable improvement is obtained, with noise levels as
low as 95.5 dBA attainable through whisper grinding.
As mentioned, several different grinder configurations were included in the experimental
design of the whisper grind test sections. Table 2 shows the results to-date of all CPX
tests conducted on two different dates after grinding.

        Table 2 – CPX test results for various diamond ground surfaces (dBA)

Test Area      6/6/03        6/6/03       6/6/03       9/8/03        9/8/03       9/8/03
               Lane 1       Lane 2       Lane 3        Lane 1       Lane 2        Lane 3
    1           96.6          96.4         NA            NA           97.5         NA
    2            NA           NA           98.1          NA           NA           98.0
    3           98.5          95.6         NA            NA           97.0         NA
    4            NA           NA           95.5          NA           NA           95.5


There was some variability between the different test areas as a function of the
configuration of the grinder. The lowest CPX noise level recorded was 95.5 dBA in Test
Area 4. Most noise levels were less than 98 dBA, still somewhat better than newly
constructed, longitudinally tined surface textures (which were ~99 dBA – see Table 1).
In terms of improved texturing and skid resistance, many documented studies have
shown considerable improvement in the skid resistance of diamond ground concrete
pavements. The degree of improvement naturally depends on the skid resistance of the
facility before grinding, from new construction (in the case of California, with
longitudinal tining) to older, polished surfaces that may have lost much of their
macrotexture. The hardness of the aggregate in the PCC is also critical to longevity of
diamond ground surfaces with respect to skid resistance. Softer aggregates, such as
limestone, are more prone to polishing, causing a loss of texture depth on diamond
ground surfaces. Most aggregates in California are much harder and thus maintain their
texture over longer time periods.
The same ADOT study for noise mitigation mentioned above also monitored the changes
in skid resistance for the same whisper grind test sections. Table 3 depicts the before and
after skid numbers, together with the percent improvements, due to diamond grinding
with various blade spacings and grinder configurations. The percent improvement for any
given test section due to grinding is shown in parentheses.




                                                                                          13
         Table 3 – Friction values and percent changes due to diamond grinding
Test Area       Before        Before        Before       After         After         After
               Grinding      Grinding      Grinding     Grinding      Grinding      Grinding
                Lane 1        Lane 2        Lane 3        Lane 1        Lane 2       Lane 3
     1            0.52          0.55          NA           0.65          0.63          NA
                                                          (25%)         (15%)
     2            NA            NA            0.56          NA            NA           0.66
                                                                                      (18%)
     3            0.49          0.51          NA           0.69          0.69          NA
                                                          (41%)         (35%)
     4            NA            NA            0.53          NA            NA           0.67
                                                                                      (26%)


The pavements shown in Tables 1, 2 and 3 were all new (with longitudinal tining) before
grinding. Therefore, the improvement in skid resistance due to diamond grinding is likely
to be even better for older PCC pavements with, for example, polished and exposed
aggregate.
As indicated in Table 3, the increase in friction values varied between 15% and 41%,
with an overall average improvement of 27%.

CRITERIA FOR USING GRINDING AS A REHABILITATION
TECHNIQUE

Currently in California, the criteria for selecting diamond grinding for candidate projects
to rehabilitate a JCP section in need of rehabilitation (while still structurally sound) are
not formally defined.
Firstly, the pavement needs to be rough enough such that the pavement needs a smoother
ride for the traveling public. Secondly, the cost of a grinding project to restore ride
quality has to be within the District’s current budgetary means and this option should
result in a lower life cycle cost than other effective alternatives.
Some considerations in setting the above criteria include:
     •   Currently, there are no objective criteria for what constitutes a “rough” pavement.
         It would be good if either an IRI level of roughness or a PI (from the California
         Profilograph), or a specific degree of joint (step) faulting was specified in order to
         qualify for a grinding project for the purpose of PCC pavement rehabilitation. If
         Caltrans eventually adopts the new Mechanistic-Empirical Design Guide, such
         input quantities will be required.
     •   One of the main reasons for diamond grinding—step faulting—is not currently
         measured or quantitatively recorded by the Caltrans PMS data collection system.
         If faulting is severe enough to be noticed by the high-speed profiler operator, it is


14
       merely noted as “faulting” but it is not quantified. It may in fact be possible to
       quantify step faulting using the longitudinal pavement profile measured by the
       Caltrans or other high-speed profilers, by subtracting the vertical elevation just
       after a joint or crack from the elevation measured immediately before the same
       joint or crack.
   •   The speed of grinding operation is a function of aggregate hardness and the depth
       of removal. Whisper grinding operations therefore have a relatively smaller
       production time. Similarly, surface longevity is also a function of aggregate
       hardness and therefore the performance can vary across different projects.
   •   Until now, the longevity of a diamond ground project was not quantified so it was
       difficult to carry out a reasonable and objective life cycle cost/benefit analysis for
       the grinding alternative. Based on the present study, an average lifespan for a
       diamond ground project is between 16 and 17 years. If a given certainty or
       reliability level in lieu of an average value is required (e.g., an 80% probability
       that a given project will last a certain number of years), the probability curves in
       Figure 6 may be used, thus obtaining an effective design life of about 14 years at
       an 80% certainty level, for example.
Another potential shortcoming to the present practice is that the smoothness achieved
after grinding is not always as good as could be achieved by most contractors, unless the
project has significant settlements or heaves. Currently, IRI is measured both before and
after grinding, while the grinding contract itself utilizes the California Profilograph with
California Test Method #526. It may be useful to “tighten up” the current smoothness
specification that contractors have to meet, or to change the spec for diamond grinding
projects to an IRI-based one using a high-speed profiler. Additionally, if significant
settlements exist, these could be leveled through slab jacking operations prior to grinding.
If the load transfer efficiency is poor, dowel bar retrofits, if properly constructed, may
help rectify this structural problem prior to grinding.
The use of a more stringent smoothness criteria, whether measured in terms of IRI from a
high-speed profiler or the PI in terms of the California Profilograph, may well extend the
design life of a diamond ground project even further than the present average of nearly 17
years, because the rate of increase in roughness is relatively constant from project to
project, regardless of the starting or ending point as measured by IRI. For example, if an
average IRI percentage improvement ratio of 2.0 instead of the assumed statewide
average of 1.78 could be used, the average design life for a diamond ground project may
result in a 20-plus year average survivability. Using an 80% reliability level, as another
example, the corresponding figure for an average IRI ratio of 2.0 would be around 18
years (see Figure 6).
On the other hand, there are certain pavement distresses or conditions that should
preclude the use of diamond grinding as a rehabilitation alternative. These include:
   1. Lack of structural integrity (e.g., voids under joints from pumping, excessive slab
      cracking and progressive cracking over time).
   2. Very poor load transfer at transverse joints as indicted by excessive faulting and
      voids.
   3. Spalling or other damage due to ASR.
   4. Freeze-thaw damage, including D-cracking.


                                                                                          15
     5. Soft aggregates in the PCC slab, such as limestone, that are prone to polish (this
        may be overcome by widening the spacing of the grinding blades).
None of these distresses would be remedied by diamond grinding alone, and the problem
would likely continue to cause pavement failure a short time after grinding. Such
precluding factors are probably considered under present Caltrans guidelines, albeit
without any truly objective criteria or measurable threshold values.
It has been shown that it is possible in California to diamond grind candidate PCC
pavements up to three times during the lifespan of the pavement. In other words, if the
service life of a well-designed concrete pavement can be extended by 16-17 years, on
average, with diamond grinding, and this technique could be applied two or three times,
then we can effectively utilize a concrete pavement, without major reconstruction, over a
very long time span with only routine maintenance—provided the pavement remains
structurally adequate. This magnitude of pavement life is associated with very good ride
quality and safety (skid) properties, and it makes diamond grinding a very competitive
option for rehabilitation of PCC pavement in California.




16
                         APPENDIX A

  Diamond grinding projects (denoted by District Number – Project
Number) analyzed and presented in this appendix, in the following order.

                               12-085UR
                               11-07620
                               07-20250
                               12-09390
                               07-19970
                               07-20240
                               12-09770
                               08-4177V
                               04-0C400
                               11-07610
                               04-0C510
                               04-0C360
                               04-0C600
                               07-18130
                               04-0C410
                               06-42170
                               04-0C370
                               07-17530
                               08-48890
                               08-36762
                               12-0A110
                               11-22300
                               08-43950
                               08-43960
                               07-16940
                               07-17200
                               07-16950
                               08-34800
                               05-23250
                               04-Dixon Ι-80




                                                                      17
                                                     IRI Tracking - Before & After Grinding - Section 12-0850U-R
                                                                       Route 22 EB: MP 0.6-13.2
                    300


                                                                                                                                   R3-3.5
                                                                                                                                   R3-5.5
                                                                                                                                   R3-6.5
                    250
                                                                                                                                   R3-7.5
                                                                                                                                   R3-10.5
                                                                                                                                   Average


                    200
 IRI, inches/mile




                    150



                                                  Diamond grinding com-
                                                  pleted by January 2003
                    100




                    50




                      0
                     7/24/98   2/9/99   8/28/99        3/15/00   10/1/00         4/19/01         11/5/01    5/24/02    12/10/02     6/28/03    1/14/04
                                                                           Date of IRI Survey




                                                    IRI Tracking - Before & After Grinding - Section 12-0850U-R
                                                                      Route 22 EB: MP 0.6-13.2
                    300


                                                                                                                                  R3-3.5
                                                                                                                                  R3-5.5
                                                                                                                                  R3-6.5
                    250
                                                                                                                                  R3-7.5
                                                                                                                                  R3-10.5
                                                                                                                                  Average


                    200
 IRI, inches/mile




                    150



                                                  Diamond grinding com-
                                                  pleted by January 2003
                    100




                    50




                      0
                     7/24/98   2/9/99   8/28/99       3/15/00    10/1/00        4/19/01         11/5/01    5/24/02    12/10/02    6/28/03     1/14/04
                                                                           Date of IRI Survey




18
                                                     IRI Tracking - Before & After Grinding - Section 07-20250-R
                                                                         I-5 NB: MP 28.9-47.9
                     250



                                                                                                                R4-34.4
                                                                                                                R4-35.4
                     200
                                                                                                                R4-37.4
                                                                                                                Average



                     150
  IRI, inches/mile




                     100

                     Diamond grinding com-
                     pleted by May 2002

                      50




                        0
                       7/24/98    2/9/99     8/28/99        3/15/00    10/1/00     4/19/01       11/5/01     5/24/02      12/10/02   6/28/03
                                                                       Date of IRI Survey




                                                     IRI Tracking - Before & After Grinding - Section 12-09390
                                                                          I-5: MP 0.00-1.68
                     350


                                                                                                                       R3-0.0
                     300                                                                                               R4-0.0
                                                                                                                       L3-0.7
                                                                                                                       L4-0.7

                     250                                                                                               R3-0.7
                                                                                                                       R4-0.7
                                                                                                                       Average
IRI, inces/mile




                     200




                     150




                     100          Diamond grinding com-
                                  pleted by February 2002


                      50




                       0
                      7/24/98    2/9/99    8/28/99      3/15/00   10/1/00   4/19/01    11/5/01     5/24/02    12/10/02     6/28/03   1/14/04
                                                                       Date of IRI Survey




                                                                                                                                               19
                                                   IRI Tracking - Before & After Grinding - Section 07-19970
                                                                   Route 134 EB: MP 0.0-13.4
                    250


                                                                                                                        R4-2.0
                                                                                                                        R4-3.0
                                                                                                                        R4-4.0
                    200
                                                                                                                        R4-6.0
                                                                                                                        R4-7.0
                                                                                                                        R4-8.0
                                                                                                                        R4-10.0
                    150                                                                                                 R4-12.0
 IRI, inches/mile




                                                                                                                        Average




                    100


                               Diamond grinding com-
                               pleted by December 2001

                     50




                      0
                     7/24/98    2/9/99     8/28/99      3/15/00       10/1/00     4/19/01        11/5/01      5/24/02      12/10/02   6/28/03   1/14/04
                                                                             Date of IRI Survey




                                                   IRI Tracking - Before & After Grinding - Section 07-20240
                                                                       I-10: MP 31.5-42.6
                    250



                                                                                                              L4-31.2
                                                                                                              L4-33.5
                    200                                                                                       L4-35.5
                                                                                                              L4-40.9
                                                                                                              L4-41.7
                                                                                                              Average

                    150
 IRI, inches/mile




                               Diamond grinding com-
                               pleted by October 2001
                    100




                     50




                      0
                     7/24/98   2/9/99    8/28/99     3/15/00      10/1/00   4/19/01    11/5/01      5/24/02    12/10/02     6/28/03   1/14/04
                                                                       Date of IRI Survey




20
                                                    IRI Tracking - Before & After Grinding - Section 12-09770
                                                                       I-405: MP 0.25-11.44


                   250



                                                                                                                   L4-1.1
                                                                                                                   R4-2.3
                   200
                                                                                                                   L4-3.2
                                                                                                                   L4-4.0
                                                                                                                   R4-4.2
                                                                                                                   L4-5.0
                   150                                                                                             L4-8.5
IRI, inches/mile




                                                                                                                   Average




                   100




                    50


                              Diamond grinding com-
                              pleted by October 2001
                     0
                    7/24/98      2/9/99   8/28/99     3/15/00     10/1/00      4/19/01   11/5/01   5/24/02   12/10/02        6/28/03     1/14/04
                                                                       Date of IRI Survey




                                                    IRI Tracking - Before & After Grinding - Section 08-4177V
                                                                      I-15 NB: MP 12.9-29.2
                   200


                   180


                   160


                   140


                   120
IRI, inches/mile




                   100


                    80
                                                                                                                     R3-20.6
                    60    Diamond grinding com-                                                                      R4-20.6
                          pleted by March 2001                                                                       R4-21.6
                    40                                                                                               R4-23.6
                                                                                                                     R3-24.6
                    20                                                                                               Average


                     0
                    7/24/98      2/9/99    8/28/99      3/15/00      10/1/00       4/19/01    11/5/01    5/24/02      12/10/02         6/28/03     1/14/04
                                                                            Date of IRI Survey




                                                                                                                                                             21
                                                  IRI Tracking - Before & After Grinding - Section 04-0C400
                                                                    I-680 NB: MP 0.0-12.6
                    250
                                                                                                        R4-1.6
                                                                                                        R4-2.6
                                                                                                        R4-3.6
                                                                                                        R4-4.6
                    200                                                                                 R4-5.6
                                                                                                        R4-6.6
                                                                                                        R4-8.6
                                                                                                        R4-9.6
                    150                                                                                 R4-10.6
 IRI, inches/mile




                                                                                                        Average




                    100
                               Diamond grinding com-
                               pleted by January 2001


                     50




                      0
                     9/27/97              2/9/99                  6/23/00                     11/5/01                   3/20/03
                                                                         Date of IRI Survey




                                                  IRI Tracking - Before & After Grinding - Section 11-07610
                                                                    I-15 NB: MP 10.0-19.5
                    160
                                                                                                                        R4-9.8

                    140                                                                                                 R4-11.5.2

                                                                                                                        R5-13.0

                                                                                                                        Average
                    120



                    100
 IRI, inches/mile




                     80



                     60
                           Diamond grinding com-
                           pleted by December 2000
                     40



                     20



                      0
                     7/24/98   2/9/99   8/28/99      3/15/00   10/1/00      4/19/01     11/5/01     5/24/02       12/10/02   6/28/03   1/14/04
                                                                    Date of IRI Survey




22
                                              IRI Tracking - Before & After Grinding - Section 04-0C510
                                                                I-80 EB: MP 11.4-30.6
                   250
                                                                         R4-11.5
                                                                         R3-12.5
                                                                         R4-12.5
                                                                         R4-12.5
                   200
                                                                         R4-14.5
                                                                         R4-14.5
                                                                         R4-17.4
                                                                         Average
                   150
IRI, inches/mile




                   100


                          Diamond grinding com-
                          pleted by December 2000
                    50




                     0
                    2/24/98                 7/9/99                11/20/00                   4/4/02             8/17/03
                                                                   Date of IRI Survey




                                              IRI Tracking - Before & After Grinding - Section 04-0C360
                                                                I-580 NB: MP 1.5-19.3
                   250



                                                                                   R4-7.2
                                                                                   R4-9.8
                   200
                                                                                   R4-10.8
                                                                                   Average



                   150
IRI, inches/mile




                   100
                         Diamond grinding com-
                         pleted by November 2000


                    50




                     0
                    4/15/98                   8/28/99                   1/9/01                        5/24/02             10/6/03
                                                                    Date of IRI Survey




                                                                                                                           23
                                                IRI Tracking - Before & After Grinding - Section 04-0C600
                                                                   Route 17: MP 7.1-8.9
                    250


                                                                                        R1-7.1
                                                                                        L1-7.1

                    200                                                                 L2-7.1
                                                                                        Average




                    150
 IRI, inches/mile




                    100
                               Diamond grinding com-
                               pleted by October 2000


                     50




                     0
                     6/4/98    12/21/98    7/9/99       1/25/00   8/12/00    2/28/01     9/16/01     4/4/02   10/21/02   5/9/03    11/25/03
                                                                        Date of IRI Survey




                                                IRI Tracking - Before & After Grinding - Section 07-18130
                                                                    I-10: MP 42.4-45.8
                    300




                    250


                                                                                                   L4-41.7

                    200
 IRI, inces/mile




                    150

                                   Diamond grinding com-
                                   pleted by July 2000
                    100




                     50




                      0
                     4/15/98    11/1/98   5/20/99       12/6/99   6/23/00    1/9/01      7/28/01    2/13/02    9/1/02    3/20/03   10/6/03
                                                                        Date of IRI Survey




24
                                                   IRI Tracking - Before & After Grinding - Section 04-0C410
                                                                       I-80: MP 10.7-13.4
                   250




                                                                                                     L3-10.7
                   200                                                                               R3-10.7
                                                                                                     R3-12
                                                                                                     Average


                   150
IRI, inches/mile




                              Diamond grinding com-
                              pleted by June 2000

                   100




                    50




                     0
                    3/11/97              7/24/98               12/6/99              4/19/01          9/1/02                1/14/04
                                                                    Date of IRI Survey




                                                   IRI Tracking - Before & After Grinding - Section 06-42170
                                                                    Route 99: MP 10.6-20.5
                   200
                                                                                                                 L3-10.7
                   180                                                                                           L3-11.2
                                                                                                                 L3-12.2
                                                                                                                 L3-13.2
                   160
                                                                                                                 L3-14.2
                                                                                                                 L3-15.2
                   140                                                                                           L3-16.2
                                                                                                                 L3-18.2
                   120                                                                                           L3-19.2
IRI, inces/mile




                                                                                                                 Average

                   100


                    80
                         Diamond grinding com-
                         pleted by June 2000

                    60


                    40


                    20


                     0
                    2/24/98               7/9/99               11/20/00                  4/4/02        8/17/03
                                                                    Date of IRI Survey




                                                                                                                                     25
                                                  IRI Tracking - Before & After Grinding - Section 04-0C370
                                                                     I-680 NB: MP 2.4-6.4
                    250



                                                                                                                    R3-2.4
                                                                                                                    R3-4.4
                    200                                                                                             R3-5.4
                                                                                                                    Average




                    150
 IRI, inches/mile




                    100


                                Diamond grinding com-
                                pleted by May 2000
                     50




                       0
                      3/11/97               7/24/98                  12/6/99                    4/19/01                 9/1/02                 1/14/04
                                                                           Date of IRI Survey




                                                      IRI Tracking - Before & After Grinding - Section 07-17530
                                                                         I-5 NB: MP 73.6-88.6

                    250

                                                                                                               R4-76.5
                                                                                                               R4-77.5
                                                                                                               R4-78.5
                                                                                                               R3-82.5
                    200                                                                                        R3-83.5
                                                                                                               Average




                    150
 IRI, inches/mile




                    100

                                            Diamond grinding com-
                                            pleted by April 2000



                    50




                      0
                     7/24/98       2/9/99      8/28/99         3/15/00         10/1/00        4/19/01     11/5/01             5/24/02   12/10/02         6/28/03
                                                                                 Date of IRI Survey




26
                                               IRI Tracking - Before & After Grinding - Section 08-48890
                                                               Route 30 EB: MP 23.1-26.5
                    180


                    160
                                                                                 R2-25.6

                    140


                    120
 IRI, inches/mile




                    100


                     80
                               Diamond grinding com-
                               pleted by April 2000
                     60


                     40


                     20


                      0
                     11/1/98     5/20/99      12/6/99     6/23/00      1/9/01        7/28/01    2/13/02      9/1/02    3/20/03
                                                                     Date of IRI Survey




                                               IRI Tracking - Before & After Grinding - Section 08-36762
                                                                  I-10 EB: MP 4.8-10.0
                    250


                                                         R4-5.9
                                                         L4-6.2
                    200                                  L4-7.2
                                                         R4-9.2
                                                         Average



                    150
IRI, inches/mile




                    100




                     50
                           Diamond grinding com-
                           pleted by March 2000


                     0
                    12/21/98      7/9/99     1/25/00     8/12/00      2/28/01       9/16/01    4/4/02      10/21/02   5/9/03
                                                                    Date of IRI Survey




                                                                                                                                 27
                                               IRI Tracking - Before & After Grinding - Section 12-0A110
                                                                   I-405: MP 2.92-9.01
                    250

                                                                                                 L4-4.0
                                                                                                 R4-4.2
                                                                                                 L4-5.0.0
                    200
                                                                                                 Average




                    150
 IRI, inches/mile




                                                                    Diamond grinding com-
                                                                    pleted by November 1999


                    100




                     50




                      0
                     9/12/98     3/31/99    10/17/99     5/4/00      11/20/00       6/8/01       12/25/01          7/13/02        1/29/03        8/17/03
                                                                       Date of IRI Survey




                                               IRI Tracking - Before & After Grinding - Section 11-22300
                                                                  I-805: MP 0.68-8.70
                    250




                                                                                                          R4-1.15
                    200                                                                                   R4-2.15
                                                                                                          R4-3.15
                                                                                                          L4-4.0
                                                                                                          R4-4.15
                                                                                                          L4-5.0
                    150
 IRI, inches/mile




                                                                                                          R4-5.15
                                                                                                          Average



                    100




                     50
                          Diamond grinding com-
                          pleted by December 1998


                     0
                    12/21/98      7/9/99      1/25/00     8/12/00       2/28/01        9/16/01        4/4/02           10/21/02         5/9/03
                                                                       Date of IRI Survey




28
                                                IRI Tracking - Before & After Grinding - Section 08-43950
                                                                  Route 91: MP 9.0-17.4
                   140



                                                                                                       L3-14.7
                   120
                                                                                                       L3-16.9
                                                                                                       Average

                   100
IRI, inches/mile




                    80




                    60
                          Diamond grinding reported
                          complete by June 1998
                    40




                    20




                     0
                    11/1/98     5/20/99      12/6/99        6/23/00         1/9/01        7/28/01     2/13/02      9/1/02         3/20/03
                                                                            Date of IRI Survey




                                                IRI Tracking - Before & After Grinding - Section 08-43960
                                                                    I-10: MP 10.6-20.0
                   140




                   120




                   100
IRI, inches/mile




                    80

                                                                                                                            R4-12.3
                                                                                                                            L4-12.3
                    60                                                                                                      R4-13.3
                                                                                                                            L4-13.3
                                                                                                                            R4-14.3
                    40                                                                                                      L4-14.3
                          Diamond grinding reported                                                                         R4-15.3
                          complete by April 1998
                                                                                                                            L4-15.3
                    20                                                                                                      R4-17.3
                                                                                                                            L4-17.3
                                                                                                                            Average
                     0
                    7/24/98    2/9/99     8/28/99      3/15/00    10/1/00       4/19/01     11/5/01   5/24/02    12/10/02      6/28/03      1/14/04
                                                                        Date of IRI Survey




                                                                                                                                               29
                                               IRI vs. Date After Grinding - Section 07-16940
                                                              I-5: MP 28.7-31.0
                    160
                                                                                                                 y = 0.0142x - 404.87
                                                                                                                       2
                                                                                                                      R = 0.7569
                    140



                    120



                    100
 IRI, inches/mile




                     80



                     60
                                  Diamond grinding com-                                                      L4-28.7
                                  pleted by October 1997
                     40                                                                                      R4-28.8

                                                                                                             Average
                     20                                                                                      Linear (Average)


                     0
                    10/22/97         3/6/99                               7/18/00                     11/30/01                     4/14/03
                                                                     Date of IRI Survey




                                               IRI vs. Date After Grinding - Section 07-17200
                                                             I-5 NB: MP 3.4-11.5
                    180
                                              IRI values from 1989 are approximate, calculated
                                              from Ride Score values. The date is also approxi-
                    160                       mate. It is likely that the IRI was a lot higher than
                                              ~160 by 1997, very likely between 180 and 200.

                    140


                    120
 IRI, inches/mile




                    100


                     80


                     60                                                                                    R3-4.3
                                                                                                           R3-5.3
                                                                                                           R3-6.6
                     40
                                                        Diamond grinding com-                              Average
                                                        pleted by October 1997
                     20


                     0
                    12/23/88   9/19/91                    6/15/94                       3/11/97            12/6/99                 9/1/02
                                                                       Date of IRI Survey




30
                                                                                        IRI vs. Date After Grinding - Section 07-16950
                                                                                                      I-710 MP 13.3-21.9


                   300
                                            IRI values from 1988 and 1990 are approximate,
                                            calculated from Ride Score values. It is likely that
                                            the IRI was somewhat higher than ~225 by 1997,
                                            very likely between 235 and 250.
                   250




                   200
IRI, inches/mile




                   150




                                                               R3-15.2
                   100                                         R3-17.9
                                                               R4-17.9
                                                               L3-20.3
                                                               L4-20.3
                                                               L3-21.3
                   50                                          L4-21.3
                                                               Average                                            Diamond grinding
                                                                                                                  completed by May 1997


                     0
                    8/11/87                    12/23/88       5/7/90        9/19/91       1/31/93      6/15/94      10/28/95       3/11/97    7/24/98   12/6/99       4/19/01     9/1/02
                                                                                                              Date of IRI Survey




                                                                                      IRI vs. Date After Grinding - Section 08-34800
                                                                                                   I-10 EB: MP 20.0-21.2
                                            250
                                                                          All IRI values between 1980 and 1990
                                                                          are approximate, calculated from Ride
                                                                                                                                                                        R4-19.3
                                                                          Score values. All dates of measurement
                                                                          except one are also approximate.                                                              R4-20.3
                                                                                                                                                                        R4-21.0
                                            200                                                                                                                         Average




                                            150
                         IRI, inches/mile




                                            100




                                             50
                                                                                                   Diamond grinding com-
                                                                                                   pleted by May 1991


                                              0
                                             5/25/79           2/18/82          11/14/84            8/11/87        5/7/90           1/31/93      10/28/95         7/24/98       4/19/01         1/14/04
                                                                                                                    Date of IRI Survey




                                                                                                                                                                                           31
                                                              IRI vs. Date After Grinding - Section 05-23250
                                                                       Route 101 NB: MP 82.2-88.2
                    120
                                                                                                                                 1.7493
                                                                                                                       y = 7E-07x
                                                                                                                           2
                                                                                                                         R = 0.0692

                    100




                     80
 IRI, inches/mile




                     60




                     40
                                                                                                             R2-82.8
                                                  Diamond grinding com-
                                                  pleted by August 1980                                      R2-83.8

                     20                                                                                      R2-84.8

                                                                                                             Average

                                                                                                             Power (Average)
                      0
                     8/17/80        5/14/83          2/7/86          11/3/88        7/31/91       4/26/94    1/20/97       10/17/99        7/13/02
                                                                                  Date of IRI Survey




                                                    IRI vs. Date After Grinding - Section 04 / Dixon Grind Project
                                                                    I-80 WB Lane 3: MP 32.52-37.52
                    250
                               All IRI values between 1980 and 1990 are
                               approximate, calculated from Ride Score values.
                               The dates of measurement are also approximate.



                    200




                    150
 IRI, inches/mile




                    100

                                                        Diamond grinding completed
                                                        sometime during 1992                                                   L3-32.5
                                                                                                                               L3-33.5
                     50                                                                                                        L3-34.5
                                                                                                                               Average
                                                                                                                               L3-35.5
                                                                                                                               L3-36.5


                      0
                     4/24/81        1/19/84        10/15/86         7/11/89         4/6/92        1/1/95    9/27/97       6/23/00         3/20/03
                                                                                 Date of IRI Survey




32
POINTS OF CONTACT

Caltrans METS – Office of Rigid Pavement and Structural Concrete
      Tom Pyle             Office Chief                     (916) 227-7281
      Charles Dayton       Contract Manager                 (916) 227-5280
      Hector Romero        Senior Engineer                  (916) 227-1989
      Robert Rogers        Transportation Engineer          (916) 227-7907

Caltrans METS – Office of Pavement Management
      Susan Massey         Office Chief                     (916) 654-4792
      Rob Marsh            Pavement Management Engineer     (916) 654-5640
      Leo Mahserelli       Pavement Management Engineer     (916) 654-2007

Applied Research Associates, Inc. – ERES Consultants Division
      Richard Stubstad     Principal Engineer               (805) 649-1111
      Michael Darter       Senior Principal Engineer        (217) 356-4500
      Chetana Rao          Senior Research Engineer         (217) 356-4500
      Walid Tabet          Senior Engineer                  (775) 338-9500

Western States Chapter, American Concrete Pavement Association
      Tom Salata           Executive Director               (949) 222-9196

Federal Highway Administration, California Division
      Steve Healow         Materials Engineer               (916) 448-5849
      Jason Dietz          Construction/Maint. Engineer     (916) 498-5886




                                                                             33

								
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