Assessing mechanical behavior and heterogeneity of low-strength mortars by the drilling resistance method

The drilling resistance method provides the material strength profile in depth. Its use is widespread for soft homogeneous materials, like carbonate stones. The application in heterogeneous materials, like low-strength mortars, is not so well established due to the irregularity of the drilling profiles yielded. This paper demonstrates the viability of the method for low-strength mortar characterization. To achieve this purpose, 19 mortar mixtures with different heterogeneity and strength characteristics were tested. Based on the analysis of the drilling measurements distribution it was concluded that the reported high variability provides valuable information on the heterogeneity characteristics of the mortars. Furthermore, the mode value of the drilling measurements is proposed as a more accurate predictor of the mortar strength than the mean value. Relationships between drilling resistance and other conventional material properties were analyzed and a better understanding of the important factors influencing drilling resistance was achieved.