A concrete cube of 150 mm was subjected to a compression test. The load at failure was found to be 700 kN. What would be tensile strength of concrete and can it be used for PQC?

Tensile strength can be found out using empirical formula, \(f_{cr}=0.7\sqrt{f_{ck}}\). The compressive strength can be found as load per area of the specimen. So, the compressive strength can be found as
\(f_{ck}=\frac{700}{150×150}=0.0311 kN/mm^2? 31.11 N/mm^2\)
\(f_{cr}=0.7\sqrt{f_{ck}}=0.7×\sqrt{31.11}=3.9 N/mm^2\)
The compressive strength for pavement is obtained as 31.11 N/mm² and flexural strength as 3.9 N/mm². As per IRC, the minimum grade of concrete for rigid pavement is M40, having 40 N/mm² compressive strength and 4.42 N/mm² flexural (tensile) strength. So, the sample cannot be used for PQC.