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RUT MIX CHALLENGE

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					RUT MIX CHALLENGE
     GAUTRANS
   RPF NOVEMBER 2006
             RUT MIX CHALLENGE
• The need arose from increased occurrence of premature
  failures
• As a result Client bodies want to move away from
  asphalt to concrete
• Better solution would be a properly designed asphalt that
  will be:
   – Rut resistant
   – Durable at low and high temperatures
   – “User Friendly” (Manufacturing & Placing)
               RUT MIX CHALLENGE
• Role players in asphalt industry to develop 2 asphalt mix
  designs namely:
   – Rut resistant intersection mix
   – Every day highway mix
• Subsequently high modules asphalt included
   – Shell with low pen binder (French Technology)
   – Sasobit with 40/50 or Sasoflex (German & French Technology)
   These mixes will then be paved on a freeway in Pretoria
     and tested for rutting, fatigue etc.
                RUT MIX CHALLENGE
• Rules for mix design:
   –   No modified binders (Rut mix & Highway mix)
   –   Any grading (Not limited to Colto Spec.)
   –   Mixes to be verified prior to paving of trials in Pretoria
   –   Reference mix to be paved and tested prior to trials being paved
RUT MIX CHALLENGE
    WEST RAND
              RUT MIX CHALLENGE
                    Mix design process

– First plant trials completed
– Intersection mix is promising (Performance testing indicates
  good rut resistance)
    • Paving trial planned on R25
– Freeway mix needs refining
    • Further plant trials planned
RUT MIX CHALLENGE
    EAST RAND
                         RUT MIX CHALLENGE
• Verification with Performance Properties
                                            Criteria set                         Performance Value
 Performance                                                       Mix 1: WC for highly     Mix 2: WC for highly
                 Test type utilized
 requirements                            Mix 1        Mix 2          trafficked roads      trafficked intersection
                                                                  Quartzite     Dolerite    Quartzite     Dolerite
                MMLS on
                briquettes at 50°C       <1.8         <1.6          1.74          1.4                       1.2
                wet [on cores] (mm)

                Average
                deformation per
Deformation     cycle in 2 000 –         <0.4         <0.35         0.12                                    0.33
resistance      3 000 range of DCT
                ()
                Gyratory voids at
                300 repetition (on a
                                         >2.7         >3.0           2.8          3.2                       4.3
                5% Marshall VIM’s
                setting)
Durability      Mod Lottman
                                        >80%         >80%            85            90                        84


                4 Pt beam fatigue
                (at 200 micron
                strain) : Reps to      >2 million   >2 million   To be tested                             3.179 m
                failure
Fatigue
                ITS (kPa)
                                        >1 000       >1 000         1368                                   1222
RUT MIX CHALLENGE
AKASIA ROAD SURFACING
           RUT MIX CHALLENGE
Akasia Road Surfacing - Mix design process

– Design in process
– Change of aggregate source (From Rooiberg to Granite from
  Buffalo quarry Naboomspruit)
– Mix type not finalized
RUT MIX CHALLENGE
    BLACK TOP




                NICO WILCOCKS
              RUT MIX CHALLENGE
                   Mix design process

– TRH8 Coarse
– Chrome Slag from Witbank
   •   High PSV
   •   Rough surface texture
   •   Good adhesion
   •   Varying surface area
   •   No swell problems
– Mix used successfully on N4 at Tollgate bypass




                                              NICO WILCOCKS
RUT MIX CHALLENGE
HIGH MODULUS ASPHALT
        (HiMA)
            RUT MIX CHALLENGE
          High Modulus Asphalt (HiMA)
                   Mix design process

Sasobit
– Soillab busy with mix designs similar to Hamburg International
  Airport (40/50 Bitumen + 3% Sasobit)

Shell
– Aggregate and bitumen samples sent to Shell Global Solutions
  France (Low pen bitumen)
ACHIEVING VOLUMETRICS
      IN ASPHALT
     BAILEY METH0D
IS NOT A SPECIFICATION!!!
          Bailey Method
• What is voids and VMA?

                 Volume Voids (3% - 6%)
                                                VMA
                 Volume Binder (10% - 17%)




                 Volume Aggregate (83% – 90%)

				
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