Autogenous Shrinkage Of High Strength/High Performance Concrete Under Semi-Adiabatic And Isothermal Curing Condition

Autogenous shrinkage is always one of the key properties in the research field of high strength high performance concrete.Autogenous shrinkage of concrete is one of significant reason which results in early-age cracking. In high strength high performance concrete mixture, due to its low water to cement ratio, thermal deformation and autogenous shrinkage occur simultaneously. If they are confined internally or externally, they may cause crack. When HPC is exposed to different curing condition at early ages, hydration of cement is changed. This may lead to different behaviors of volume change in HPC. In this Paper, the behavior of autogenous shrinkage strain of high strength high performance concrete was investigated experimentally under multi-parameters including water to cement ratio, different mineral admixtures and different temperature histories. And the influence of these multi-parameters on mechanical properties、semi-adiabatic temperature rise curves、thermal deformations and autogenous shrinkage strain was discussed. The conclusions based on the present research work can be drawn as follows:1、When the water-cement ration increases, it can significantly delay the setting time of concrete.The setting time is putted off after compounding of mineral admixtures. The semi-adiabatic temperature curing condition reduces setting time.2、The higher the water-cement ratio, the lower strength and the increase velocity. The compressive strength is decreased after compounding of mineral admixtures,especially at early-age. The semi-adiabatic condition accelerated increasing rates of compressive strength.3、The lower the water-cement ratio, the higher the semi-adiabatic temperature rise and its rising rate. The higher the semi-adiabatic temperature rise and its rising rate is decreased after compounding of mineral admixtures.4、The lower the water-cement ratio, the higher the thermal deformations of concrete. The thermal deformation is bigger under the semi-adiabatic temperature curing condition then under isothermal curing condition. After compounding of mineral admixtures, the thermal deformation is decreased.5、The total shrinkage is increased after compounding of granulated blast furnace slag under semi-adiabatic temperature curing condition, while it is decreased under isothermal curing condition. The total autogenous shrinkage is decreased after compounding of fly ash under different temperature histories. The influence of semi-adiabatic temperature curing condition on the increase of total shrinkage is significant.6、The autogenous shrinkage under semi-adiabatic temperature curing condition is bigger than it under isothermal curing condition. The autogenous shrinkage is increased after compounding of granulated blast furnace slag under semi-adiabatic temperature curing condition, while it is decreased under isothermal curing condition. The autogenous shrinkage is decreased after compounding of fly ash under different temperature histories.