A study of the effect of some parameters on the compressive strength of infilled concrete blockwork masonry

Abstract

The compressive strength of concrete masonry depends on various parameters. The focus of this study was to investigate the effect of different components, (i.e. the concrete infill strength, the block strength, and the amount of polypropylene fibre-reinforcement mixed with the concrete infill), on the compressive strength of infilled concrete masonry. Load-Displacement behaviour of each block was investigated. The effect of Poisson's ration on the load capacity of the specimens was also analysed. The concrete infill strengths selected were C7, C20 and C30. Two types of blocks were used, with average compressive strengths of 7.33N/mm2 and 8.73N/mm2. The amounts of fibre-reinforcement used were 0.1% and 0.2%, by weight of concrete. A total of forty-two concrete block specimens (including six unfilled blocks) were tested to failure. For both types of blocks, there was an increase in the compressive strength of the specimens, when the infill strength increased. However, the infill became less effective when its strength increased. The block strength also proved to be effective on the strength of the specimens. The amount of fibre-reinforcement had different effects of different specimens, with 0.1% and 0.2% amounts being more effective for smaller grades of concrete. When the strength of the concrete infill increased, most of the specimens experiences a brittle mode of failure, with a larger displacement taking place at a load very close to failure load. For smaller grades of concrete infill, fibre-reinforcement was necessary to increase the load-carrying capacity, even after initial cracking. As the infill strength for the unreinforced specimens increased, the values of Poisson's ratio increased as well, resulting in a complete failure at a compressive strength much lower than the infill strength.