Self-Consolidating Concrete for Pre-Stressed Applications – Phase 2: Bridge Construction and In-Place Performance.

摘要

Prior to statewide acceptance of self-consolidating concrete (SCC) in precast, prestressed bridge member production, the Alabama Department of Transportation sponsored an investigation of the material to be performed by the Auburn University Highway Research Center. Two parts of that research are presented in this report: an extension of an earlier laboratory investigation of fresh stability test methods to quantify the unique fresh behavior of SCC, and a field investigation of as-built material and long-term structural behavior in the first full-scale SCC girders produced and placed in an in-service bridge in Alabama. During the laboratory investigation, the Visual Stability Index, Sieve Stability, and Surface Settlement tests correlated most strongly to multiple measures of hardened concrete uniformity; a testing protocol utilizing these test methods is recommended. In the field investigation, the utilized SCC exhibited slightly increased time-dependent creep and shrinkage, at least in representative cylinders. Long-term SCC-girder prestress maintenance was found to be practically identical and at least as conservatively predictable as in companion, geometrically identical vibrated-concrete (VC) girders. Full-scale elastic responses to the weight of the cast-in-place deck and to service-level live loads were also practically identical in the SCC and VC girders, and SCC performed more conservatively than expected of VC of the same elastic stiffness. Use of cylinder-measured mechanical and time-dependent property results led to conservative predictions of full-scale behavior, and use of design properties led to highly conservative predictions. Based on these results, SCC is an acceptable alternative to VC for precast, prestressed girders when using current design and production procedures.