Properties of self-compacting concrete prepared with ternary Portland cement-high volume fly ash-calcium carbonate blends

摘要

Concrete manufacturers practically reduce negative environmental impacts and improve cost effectiveness in the industry by replacing a portion of the cement with a high volume of waste product. The use of additive from waste to increase value is considered, especially high performance concrete. Self-compacting concrete (SCC) is considered a high-performance concrete because of its workability and it can flow fill formworks with congested steel bars but no vibrator compaction. This research studies properties of SCC mixed with different levels of fly ash (FA) and calcium carbonate powder (CC). Ordinary Portland cement was replaced by FA at 20 %, 30 %, and 50 % by weight and calcium carbonate at 5%, 10 % and 20 % by weight. The total powder material content was 550 kg/m3, and the water to cementitious ratio of 0.28 remained constant for all mixtures. Properties of SCC were studied including workability and properties of different mixtures of fresh and hardened concrete. The results show that the SCC containing a high volume of ternary blends with FA and CC that is met the EFNARC standard requirements of filling ability, passing ability and resistance to segregation. An increment of FA and CC led to a decrease in unit weight, strength and shrinkage, but it increased the air content and water absorption. The highest compressive strength was more than 70 MPa at 120 days. Moreover, SCC mixtures comprising 70 % had a compressive strength more than 50 MPa. The microstructural analysis found that calcium-silica ratio (CaO/SiO2) played a development in the compressive strength and the SCC cost was reduced to 8–21 %.