Matthew D. D'AmbrosiaDavid A. LangeZachary C. GrasleyJeffery R. Roesler...
p.85-96页
查看更多>>摘要：The use of high-performance concrete (HPC) for transportation structures was the subject of a 3-year study that involved field investigation, laboratory experiments, analysis, and modeling. The field study involved instrumentation and analysis of six HPC bridge decks. The laboratory component characterized early-age thermal, shrinkage, creep, and cracking behaviors. A three-dimensional finite element model was used in conjunction with material models to analyze and predict creep and shrinkage behavior and to investigate structural and material interactions. This paper focuses on the field component of the project and discusses the instrumentation, deformation measurements, and analysis of bridge decks in Illinois. The bridges were instrumented to understand the development of shrinkage and thermal stress in concrete bridge decks with the use of various materials and structural components. The results indicate that the stress development due to daily temperature cycles and long-term temperature changes are relatively small compared with the stress development due to drying shrinkage. According to model simulations, a 15% to 40% reduction in shrinkage would reduce the stress level enough to prevent most cracking. Although drying shrinkage is the major driving force for stress development, the interaction of concrete shrinkage and structural restraint influences the magnitude of the stress and is linked to the propensity for early-age cracking.
W. Micah HaleThomas D. Bush, Jr.Bruce W. RussellSeamus F. Freyne...
p.97-104页
查看更多>>摘要：Often, concrete is not mixed or placed under ideal conditions. Particularly in the winter or the summer months, the temperature of fresh concrete is quite different from that of concrete mixed under laboratory conditions. This paper examines the influence of supplementary cementitious materials on the strength development (and other hardened properties) of concrete subjected to different curing regimens. The supplementary cementitious materials used in the research program were ground granulated blast furnace slag (GGBFS), fly ash, and a combination of both materials. The three curing regimens used were hot weather curing, standard curing, and cold weather curing. Under the conditions tested, the results show that the addition of GGBFS at a relatively low replacement rate can improve the hardened properties for each curing regimen. This improvement was noticeable not only at later ages but also at early ages. Mixtures that contained both materials (GGBFS and fly ash) performed as well as and, in most cases, better than mixtures that contained only portland cement in all curing regimens.
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