Axial compression test of masonry short columns with ultra-high performance mortar

To improve the mechanical properties of masonry columns, a new masonry column with UHPM (UMC) based on the ultra-high performance mortar (UHPM) was proposed. Axial compression test were carried out on two groups of UMC with fired brick and concrete brick. By comparing with the conventional masonry columns (MC), the stress mechanism and failure mode of UMC were discussed. The applicability of formula for calculating the axial compression bearing capacity of masonry columns in the current specification to UMC was evaluated, and the prediction formula for the axial compression bearing capacity of UMC was proposed. Analysis results show that the whole stress process of UMC and MC is similar, which both experience the stress stage before cracking, cracking development stage and failure stage. The initial cracking load of UMC is much higher than that of MC, where, the values of UMC with fired brick and concrete brick are 2.36 and 2.45 times than those of MC, respectively, and both are greater than the ultimate load of MC. Both the UMC and MC lost their bearing capacity due to the block failure. The failure mode of MC shows obvious brittleness, and the cracks mainly develop at the interface between the mortar and the block. However, the failure of UMC shows good ductility, and the crushing degree of block is much larger than that of MC. Compared with MC, mortar in UMC is no longer a weak part, and the UHPM plays a constraint role on the lateral deformation of the block, which can significantly improve the bearing capacity of the masonry column. The compression bearing capacities of UMC with fired brick and concrete brick are 1.74 and 2.00 times that of MC, respectively, indicating that the application of UHPM in masonry structure is quite feasible. The strength calculation formula for MC in the current specification will overestimate the bearing capacity of UMC. The proposed UMC strength calculation formula for UMC takes into account the strength of block and the constraint effect of UHPM on the block. © 2022, Editorial Department of Journal of Traffic and Transportation Engineering. All right reserved.