Determination of the Mortar Strength Using Double Punch Testing

The paper presents results of the Authors' own studies on mortar strength using the DPT method. The results of experimental tests and numerical analyses are compared. Numerical analyses were performed for the 3D model, which consist of mortar, capping gypsum and steel punch. In the numerical simulation mortar was modelled using the Drucker-Prager plasticity model with strain hardening in the compression regime. For tension, a multidirectional smeared crack model was applied. The interface elements were used between mortar and gypsum and between the gypsum and steel punch in order to model the behavior of these joints. A good agreement between the results of numerical calculations and experimental research was obtained. On the basis of calibrated numerical model the effect of lining gypsum and the influence of sample thickness was analyzed.