2017 Volume 71 Issue 1 Pages 331-338
The use of supplementary cementitious materials, such as slag or fly ash blended cement, in concrete have been increasing recently considering the environmental impact of Portland cement and use of industrial by-product as well as for better strength and performance. However, it has been reported that slag blended cementitious materials have low resistance in freezing and thawing environment. In this paper, the influence of blast furnace slag addition on the expansion and shrinkage of blended cement paste during freezing and thawing processes was studied. The expansion and shrinkage experimental results show that the slag addition causes an increasing expansion at around －40℃. Furthermore, the curing period influences the expansion and shrinkage behavior of blended cement. The behavior was analyzed using the model proposed by authors. By comparing the simulation and experimental results, the model could reproduce the expansion and shrinkage behavior of slag blended cement past cured at 70 days. However, the simulation results are not agreed well with experimental data for the specimens cured at 14 days. The microstructure of early age sample might be broken during the processes of freezing and thawing and causes the differences. Furthermore, expansion behavior at around －40℃ affect the volume changes due to hydraulic pressure.
