A Qualitative Study of Thermochemical Degradation Related with Concrete and Mortar Strength

The nondestructive methods applied to the evaluation of concrete use different parameters to be related in the estimated resistance of concrete or other properties. The conducted study has evaluated a qualitative method of thermochemical degradation in concrete and mortar using a solvent acid whose chemical energy is capable of degrading the material. The reported study consisted in performing laboratory tests on mechanical compressive strength of concrete and mortar and thermochemical tests performed on little cores of concrete or mortar immersed in hydrochloric acid contained in a calorimeter system, obtaining several parameters as the time of thermal equilibrium, increase of temperature, degradation energy, and mass loss due to the thermochemical reaction. From the obtained results, these variables were analyzed and served as a parameter to be related with the concrete or mortar strength. The best parameter proved to be a good estimator was the increase of temperature and its degradation energy, whose value was inversely proportional to the strength of the material. Also, it is found that the most significant mechanisms that influenced the thermochemical reaction are the calcium content and the water chemically bound in the cement paste to perform the thermochemical test.