Research On Early Age Shrinkage-Cracking Characterization Of Concrete With Multi-Components Admixtures

Due to the further development of cement-concrete research, the multi-components mineral admixtures is important for modern concrete, therefore, to explore a suitable mineral admixtures has become one of the main research contents. With the industrial wastes such as steel slag, slag and fly ash functioning as the mineral admixtures, we can save the resources, and improve the strength and durability of the concrete performance. And with its wide distribution and large quantity, industrial wastes has high application and research value. As the concrete cracking at the early age is closely relate to the concrete multi-components admixtures. The research on concrete with multi-components admixtures is benefit to the safety and durability of engineering structures.The paper studies the hydration mechanism of cementitious materials which includes steel slag, slag and fly ash, and further explores their microstructure. It analyzes the early age cracking characterization of the three cementitious materials under the conditions with one, two or three kinds of admixtures respectively. Firstly, through the experiments, we get the proportion of the corresponding admixtures when the multi-composition concrete compressive strength is highest. Then we adopt plate-test and ring-test methods, to study the early age cracking characterization of multicomponents admixtures concrete. From the results, we can get the following conclusions:in the plate-test experiment, the anti-cracking performance of the concrete is the best when the slag replaces the cement at the proportion of 30%; under the two admixtures conditions, the anti-cracking performance of the concrete is the best when the steel slag and fly ash as the equal mixture components replace cement at the rate of 30%; under the three admixtures conditions, the anti-cracking performance of the concrete is the best when the steel slag, slag and fly ash as the mixture components under the proportion of 1:2:1 replace cement at the rate of 30%. And in the mortar specimen experiment, the anti-cracking performance of the concrete is the best when the three cementitious materials replace the cement at the rate of 40%.