Experimental study on axial compressive behavior of stone masonry with ultra-high performance mortar

Ultra-high performance mortar (UHPM) has been proposed to replace conventional mortar (CM) as it can improve the compressive performance of stone masonry structure. To investigate performance features such as failure modes, load-versus deformation and ultimate compressive strength, eighteen UHPM and CM stone masonry specimens were tested under axial loading with mortar type, fiber type, mortar thickness and stone block surface condition as the main parameters. The test results indicate that for UHPM specimens, the primary cause of failure is the cracking of stone blocks rather than the mortar joints. And the cracking and ultimate compressive strength is 182.1% and 245.3% higher respectively compared with that of the CM ones. mechanism possible explanation is that stone blocks in stone masonry with UHPM are in a tri-axial compression due to the confinement effect of UHPM material which possesses high elastic modulus and low Poisson's ratio. UHPC without fibers recommended for stone masonry structures as the theoretically positive effects of steel and PVA fibers on UHPC did not show up in this experiment. The artificial sand blasting treatment on stone surface exerts little effect on the compressive performance of UHPC stone masonry. Based on the test results, a new formula of EC6 is recalculated and the ratio between recalculated and test values is 0.97 with a variance of 0.07. However, for the equation used to predict the compressive strength of UHPM stone masonry is still need to improvement.