Out-of-plane flexural behaviour of reinforced mortarless concrete block masonry: An experimental study

Abstract

The lateral resistance of mortarless masonry is relatively lesser than the conventional mortared masonry due to the absence of mortar joints. To increase its resistance against out-of-plane loads, grouting and reinforcement in hollow cores of the interlocking blocks can be adopted. In this study, flexural behaviour of the reinforced mortarless masonry (RMM) panels was investigated by testing twenty-four RMM panels under out-of-plane loads. The influence of mortarless block types (both single and double webbed), longitudinal reinforcement ratios and slenderness (height to thickness ratio) were examined. Failure patterns, load-displacement responses and flexural ductility characteristics of the RMM panels were assessed and presented. The experimental results revealed that all RMM panels irrespective of changing parameters failed in a ductile manner with opening of dry joints at the tension side of panels, followed by propagation of flexural cracks in the grouted cores and yielding of reinforcement. The single webbed block panels exhibited higher flexural strength as compared to double webbed blocks, and the high reinforcement ratio also enhanced the flexural capacity of tested panels. The ductility of RMM panels was reduced as the wall slenderness increased from 6.3 (half-height panels) to 12.6 (for full-height panels). Prediction of flexural capacities of the tested RMM panels using three different Masonry design Standards (AS 3700, CSA S304 and TMS 402) were found conservative with a safety ratio of at least 1.2. The Australian Masonry Standards (AS 3700) was most conservative in predicting the out-of-plane bending capacities of the RMM panels tested in this study by an average safety ratio of 1.9 compared to experimental results.