Question

Following compound can be used as accelerators except

• A. $CaC{l}_2$
• B. $NaCl$
• C. $CaS{O}_4$
• D. $N{a}_{2}S{O}_4$

Answer 1

The correct option is C $CaS{O}_4$

$CaS{O}_4$ is used as retarder so cannot be used as accelerator. Retarder is used to slow down the setting rate of concrete which is used to counteract the accelerating effect of hot weather on concrete setting. Ex. $CaS{O}_4$. Accelerators make concrete set faster rapidly after mixing with concrete. As high temperature after cause an increased rate of hardening which makes placing and finishing difficult. Ex. : $CaC{l}_2,NaC{l}_2,N{a}_{2}S{O}_4$