Assessment of Compressive Strength of Concrete Bridge using Destructive/Non-Destructive Tests at Elevated Temperature

Abstract

Concrete bridge structure when subjected to high temperature, exhibit good behaviour as a result of their low thermal conductivity associated with their great capacity of thermal insulation. However, there is a fundamental problem of ‘spalling’ caused by high temperatures on concrete. To investigate the problem caused by high temperatures, concrete cubes of grade 25 were prepared and cured in water for 28 days and subjected to elevated temperature at varying degrees ranging from 100 to 600 oC for various timing of ½, 1, 1½, 2, 2½ and 3hrs, after which non-destructive and destructive testing methods were carried out on the samples to compare the compressive strengths obtained. Direct and deductive results obtained shows that there was a drop in the compressive strength of the specimen after it had been subjected to elevated temperature for all methods. The result also showed that the non-destructive testing method is more reliable as it also allows a physical examination of the interior properties of the samples. In addition, the combined pulse velocity and rebound index method has no effect on the accuracy of the interpretation. However, it is clear that any of the three methods can be adopted depending on the situation at hand.