Question

All ________ tend to accelerate the setting of cement and to improve the strength of concrete in early stages.

(a) Chlorides

(b) Sulphates

(c) Sodium

(d) Potassium

I have been asked this question in a national level competition.

The above asked question is from Properties of Cement Concrete topic in section Cement Concrete Construction of Construction & Building Materials

Answer 1

Correct answer is (a) Chlorides

Best explanation: On other hand, the sulphates tend to retard the setting of cement and to discourage the strength of concrete in early stages. It is found that the net effect of these two contradiction reactions in the fall in strength of concrete to the tune of about 8% to 20%.