The accelerating and retarding admixtures can be compared as follows.
On the basis of |
Accelerating Admixture |
Retarding Admixture |
Hydration process |
Due to accelerating admixture, hydration process completes very quickly. Hence hardening of concrete takes place earlier. |
Due to retarding admixture, hydration process completes slowly, hence concrete hardens very slowly. |
Setting time |
Setting time of concrete reduces due to addition of accelerating admixture. |
Setting time of concrete increases due to addition of retarding admixture |
Weather condition |
It is useful for concreting in cold weather condition. |
It is useful for concreting in hot weather condition |
Use |
1. It is applicable where delay in construction is not allowed i.e. road construction. 2. It is useful where quick setting is required i.e. in underwater construction. 3. It is beneficial where rapid hardening of concrete is necessary i.e. in case of high rise structures. |
1. It is applicable where high heat and ibrations are required to reduce i.e. in machine foundations and nuclear power plant. 2. It is useful where slow setting of concrete is required i.e. in extreme hot* weather concreting. 3. It is beneficial where slow hardening of concrete is necessary i.e. in mass concrete structures. |