Experimental investigation of dry-bed joints in rubberized concrete interlocking masonry

Waste materials are added to the ingredients of interlocking concrete masonry as a partial replacement for cement or sand to minimize resource depletion and environmental degradation while enhancing interlocking masonry characteristics. Rubberized concrete interlocking bricks (RCIBs) are newly developed interlocking masonry units, however, their bed-joint behavior is complex owing to the presence of waste materials and geometric imperfections. This study aimed to investigate the behavior of the dry-bed joint under compression and out-of-plane loading. Seven single-joint prisms (SJPs), five multiple-joint wallets (MJWs), and three RCIB hollow wall panels (HWPs) were prepared and tested under axial and out-of-plane lateral loading, respectively. The local contact stiffness of the bed joints in SJPs was found to be half of the stiffness of the prisms when the joint surface areas were almost in full contact. The maximum variation in the joint closure of the MJWs (0.68 mm) was 3.8 times higher than that of the SJPs (0.18 mm) owing to the multiple effects of contact-area irregularities and height differences between adjacent bricks. All the tested MJWs and SJPs exhibited similar joint-closure behavior during their initial compressive loading stages up to ∼0.65%–0.85% and 0.5%–0.7%, respectively, of the ultimate load. With a joint opening of 10.38 mm, the RCIB-HWPs achieved an ultimate lateral loading of 11.70 kN. The largest out-of-plane lateral loading validated the efficiency of the interlocking keys, which reduced brick slippage under lateral loading, indicating RCIB-HWPs stability.