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					 ALDOT – 2008 CE/ME Conference


 Self-Consolidating Concrete
     (SCC) in Drilled Shafts

By: Anton Schindler, Ph.D., P.E.
    Gottlieb Associate Professor
    Department of Civil Engineering
    Auburn University
    September 25, 2008 – Montgomery, AL
Self-Consolidating Concrete (SCC) ?
            ACI 237 Definition
“SCC is a highly flowable, non-segregating
concrete that can spread into place, fill the
formwork, and encapsulate the reinforcement
without any mechanical consolidation.”




  Conventional-slump                    SCC a.k.a
  drilled shaft concrete   High-performance drilled shaft concrete
Problems with Drilled-Shaft Concrete




                  Very tight rebar cages
                  Very large shaft diameters

                  Tremie placement

                  Extended placement times

                  Bleeding and segregation?
Problems with Drilled-Shaft Concrete
Problems with Drilled-Shaft Concrete
Problems with Drilled-Shaft Concrete
Conventional Concrete   Self-Consolidating Concrete
               Tremie




                                          Tremie
                                 Debris
      Debris
        Use of SCC for Drilled-Shafts

   SCC technology has great potential for drilled-
    shafts as it:
       offers high flowability through reinforcement
        cage
       reduces the amount of bleed water
       offers sufficient workability after extended
        times (6-10 hours)

   SCC may thus minimize some of the problems
    encountered in the past
     Slump Flow Test (ASTM C 1611)

   Measures the spread of
    concrete
   Quantifies the ability of the
    concrete to flow and fill the
    drilled shaft
                     Slump Flow

   Typical Slump Flow for SCC: 26 to 30 in.
   Recommended slump flow for shafts: 18 to 24 in.
       (Note: 16 in. slump flow ≈ 9 in. slump)
Example of SCC Fresh Properties
    IBRC Project in South Carolina

   6 ft diameter x 30 ft deep
   One with SCC, one with SC Coastal Mix
   Heavy rebar to match project
   Construct with slurry
   Exhume and examine
   Cores
       Strength testing
       Permeability
Rebar Cage
Experimental Shafts - Construction
Exhume Shafts




        (6 ft diameter, 30 ft deep)
Cutting & Coring
Conventional      SCC 6 ft
6 ft from base   from base
                 Load Test Shafts
   1 x SCC & 1 x Coastal Mix
       6 ft Dia. x 71 ft deep
   Load test shafts with Statnamic technology
   Conventional Concrete Shaft:
       Loaded with 2450 kips
       Dtotal = 0.35 in., Dperm = 0.19 in.
   SCC Shaft:
     Loaded with 2521 kips
       Dtotal = 0.30 in., Dperm = 0.15 in.
   Both shaft mixtures had similar load-
    displacement response and performed well
          SCC Production Shafts

   Smaller of two bridges was constructed with
    SCC
     6 SCC production shafts were built

   Monitored water content in aggregate
    closely to minimize segregation
   No significant problems encountered
Experimental Castings: B.B. Comer
                   September 2008
                   Thanks to:
                    Steve Beeler (ALDOT)
                    Johnny Baird (ALDOT)
                    Scott Bridge
                    Russo Corp.
          IBRC Project in Alabama
Research Objectives:
1. Develop a high-performance drilled shaft
   (HPDS) concrete mixture
       Use in foundations of B.B. Comer Bridge (1st
        Div.)
2. Evaluate the performance of HPDS concrete
   during placement
3. Evaluate the in-place properties of shafts
   constructed with HPDS concrete, with various
   state-of-the-art NDT techniques
Experimental Castings: B.B. Comer
  August 2008




                     SCC
    National Use of SCC in Drilled Shafts

   I35W Replacement Bridge, Minnepolis, MN
       +80 shafts, 100 to 120-ft deep, 7- and 8-ft diameter




                 Source: Dr. K. MacDonald (NRMCA 2008)

   Mulleca River Bridge, NJ
                 Closing Comments
   SCC technology has great potential for drilled-shafts:
       SCC provides a uniform upwards flow of the
        tremied concrete
           No debris is trapped against the side of the
            shaft
           Homogenous concrete is obtained in the shaft
       SCC will reduce the amount of bleed water
       SCC has sufficient workability after extended
        times (6-10 hours)
   SCC may thus minimize some of the problems
    encountered in past projects
        Thank you for listening.
       Questions are welcome !

By: Anton Schindler, Ph.D., P.E.
   Gottlieb Associate Professor
   Department of Civil Engineering
   Auburn University

				
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