Improving the properties of concrete using in situ-grown C-S-H

Abstract

Enhancing the properties of concrete using C-S-H seed has been a challenging task due to its agglomeration in the cement matrix. Here, for ensuring synthetic C-S-H disperse well in the cement matrix, it was first synthesized in situ on fly ash (FA) by co-precipitation method, and the C-S-H grown in situ on FA (C-S-H@FA) was received. And then, its phase composition, morphology and particle size distribution were studied. After that, its effect on the hydration kinetics of cement, and the workability, strength development, pore structure, durability of concrete was explored. The results showed that the hydration of cement can be stimulated more dramatically by C-S-H@FA when compared with C-S-H, as well as the strength development of concrete. Besides, the addition of C-S-H@FA can refine the pores in concrete, and make concrete more compact than incorporating C-S-H. Furthermore, when C-S-H was replaced by C-S-H@FA, the carbonation resistance and drying shrinkage resistance of concrete was improved. Therefore, it can be concluded that the C-S-H grown in situ on FA has better dispersibility than C-S-H in concrete, improving the comprehensive properties of concrete more effectively.