Application of a micromechanical model of three phases to estimating the porosity of mortar by ultrasound

Among the factors that affect the durability of cement-based materials, porosity is important due to its role in transporting substances inside the material. Porosity can be determined using destructive testing methods, but the civil construction industry needs a nondestructive method for the estimation of the volume of pores in cement-based materials to evaluate the deterioration process.In this investigation, a micromechanical model of three phases developed in a previous paper is used to estimate the porosity of a series of mortar samples. The proposed model takes into account the microstructural characteristics and elastic properties of the constituent phases. In a first stage, the model is used to predict the influence of both the volume fraction of sand and pores and the elastic constants of the matrix and the sand on the ultrasonic velocity. Next, experimental measurements are made on a series of mortar samples of varying water/cement ratio, cement type and sand concentration, with the results used to demonstrate that porosity can be estimated using the proposed nondestructive method.