Characterisation and strategies for mitigation of the contact surface unevenness in dry-stack masonry

•Drystack masonry suffers from surface unevenness related stress concentration.•Matrix based tactile surface sensors were used to quantify contact pressure.•Micro finite element for surface unevenness was formulated and validated.•Strategies for mitigating stress concentration examined. Contact surface unevenness of the dry-stackable, interlocking blocks adversely affects the constructability of the drystack system. This paper presents the contact surface characteristics of these blocks and strategies for mitigating the unevenness through systematic experimental and numerical studies. First, the contact surface characteristics of the dry-stackable blocks have been examined experimentally using matrix based tactile surface sensors (MBTSS). High peak pressure locations on the contacting interfaces have been identified; these locations have remained unaffected by the level of the applied load in the experiment. A micro finite element modelling method incorporating the uneven contact surface has been formulated and the parameters calibrated using the experimental data. Two strategies for minimising the contact surface unevenness are then proposed (1) grinding of the surfaces of the blocks and (2) embedding a packing material between the surfaces. Both strategies have been analysed through the finite element model. The peak contact pressure is shown to have reduced considerably for the grinding strategy and when an auxetic fabric is used as an insert between the contacting surfaces of the blocks.