Experimental investigation of dry joint surface and closure characteristics of interlocking blocks under compression

Interlocking dry stack masonry has several benefits over the conventional masonry because of its ease of construction and higher compressive strength due to the absence of mortar joints. Dry contacting surfaces between the blocks play a major role on the performance of dry stack masonry. In this study, the characteristics of the dry contacting surfaces of the concrete blocks have been experimentally examined. The contact surface area between two blocks under progressive compression load is determined using a matrix based tactile surface sensor positioned between the contacting surfaces of the two adjacent blocks. The tactile sensor determined both the contact area and the contact pressure distribution between the block surfaces. The contact surface area was found to be progressively increasing from about a minimum of 15% to a maximum of 95% of the net area with the progressive increase in compressive load. In addition, the closing deformation between the two surfaces under the compressive load was determined using a non-contact digital image corre-lation method. From the consecutive images of the closing deformation of joints, vertical strain normal to the interface was determined. The synchronised contact stress – joint closing deformation plots have shown re-markable consistency and typically contained a progressive stiffening of the dry interface at low load levels