The effects of different curing conditions on the properties of reactive powder concrete

The topic of cement replacement with cement-based materials friendly with environment is the interested aim and with economic considerations started play important role in concrete industry. This topic has been extended to include a new generation of ultra-high performance concrete and it called reactive powder concrete (RPC). It is a type from concretes with high performance and high durability. RPC has many differences from conventional concrete and those differences summarized by its unique mix design considerations and producing techniques, usage of cement in high amount, siliceous material addition, using high amount of new generation water reducer, and also reduction of water / binder ratio. The main goal of this study is utilization of fly ash (FA) as replacement with Portland cement, and replacement the fine partition of sand by and pumice powder to investigate the influence of them on the mechanical performance of RPC, with presence of silica fume as fixed at 20% of cement for all trial mixes. Experimental program includes ten trial mixes. Fly ash content was 30%, 40% and 50% by weight of cement. Pumice powder content was 0%, 10% and 15% by the weight of fine partition of sand. Water/binder ratio and superplastizer were fixed at 0.2 and 0.03 respectively. By using three curing conditions included (standard normal water curing, laboratory room curing and hot water curing), production of reactive powder mortar sampels successfully carried out at the minimum compressive strength of 97.88 MPa in age of 28 days at standard water curing condition and by utilization of 0% pumice powder and 50% fly ash. 123MPa has been achieved at 28 days by utilization of 30% fly ash and 10% pumice powder under hot water curing. Depending on the results of compressive strength in 28 days, microstructure of mortars by SEM test have been conducted for eight trials mixes.