Influence of blocks and grout on compressive strength and stiffness of concrete masonry prisms

•Failure modes of grouted and ungrouted masonry prisms are carefully described.•Impacts of using low strength and high strength blocks are presented.•The effectiveness of using grout or increasing grout strength is discussed.•The experimental results complement the existing database related to the subject.•Response surfaces, contour graphs, and new empirical equations are presented. This paper aims to evaluate the influence of concrete blocks and grout’s properties on the masonry’s compressive strength and stiffness. Prisms were produced with blocks and grouts with different strength levels, and mortars with strength of 70% of the blocks’ net area strength. It was possible to understand the effects of using low strength and high strength blocks, check the effectiveness of using grout or increasing its strength, and develop response surfaces, contour graphs, and empirical equations. Predictions about the masonry failure mechanisms are proposed for different block and grout combinations. It helps the designer to associate strength and failure mechanisms, prevent or mitigate their undesirable consequences, and eliminate brittle rupture modes. Results complement the existing database and can be used to properly select blocks and grout for masonry structures.