The Research on Composition Design and Hardening Accelerating Effect of Na+ & K+ Ions-Free Concrete Hardening Accelerator

By means of orthogonal experimental design, the composition (including Calcium formate, Ferric sulfate and Crystal-embryo) of Na+ & K+-free concrete hardening accelerator is designed, and the hardening accelerative effect of the concrete hardening accelerator is studied. The experimental result indicate that there are the interactions between compositions each other, the optimal combination of the factors is 4:5:3 (Calcium formate: Crystal-embryo: Ferric sulfate).By this combination, the concrete hardening accelerator is prepared. The early strength of the concrete which mixed with the concrete hardening accelerator can be enhanced 43%(1-daystrength), 47% (3-day strength), 39%(7-day strength), and 31%(28-day strength) compared with the controlled concrete. By altering the strength grade and the breed of the cement, the adaptability of the concrete hardening accelerator is studied too.