For concrete exposed to a very aggressive environment the w/c should be lower than ______

Approximate ratio of direct tensile strength to flexural strength is ________

How many types of sulphates attack occur in concrete?

What is internal sulphates attack?

The addition of a pozzolanic admixture such as fly ash reduces the ________

Plain cement concrete is strong in taking _______

Strength of concrete increase with _____

The breaking up of cohesion in a mass of concrete is called ____