Experimental and numerical investigations of the tensile behaviour of steel-TRM prepared with recycled glass sands and lime

Abstract

Due to the decline in the material strength and increase in natural loading, the need to strengthen historical masonry buildings is vital, and different techniques have been used to enhance the structural performance of those buildings. Textile reinforced mortar (TRM) composite systems are one of the newly developed techniques that has attracted increasing interest from researchers. To investigate the feasibility of the use of more eco-friendly materials in mortars, recycled glass sand (RGS) is substituted for natural river sand in the preparation of mortar used in the TRM system, as well as lime as a partial cement replacement. RGS was substituted for river sand at 50% and 100%, and lime was substituted for cement at 50%. A total of ten mix proportions were prepared. The mechanical properties of the mortar were analysed in terms of the flexural strength and compressive strength at 7 and 28 days. The results showed that the strengths tend to decrease as the lime and RGS proportion increases. There are the maximum average reductions of 40.3% in flexural strength and 60.4% in compressive strength for the samples with 50% lime replacement, and 38.3% in flexural strength and 33.8% in compressive strength for the samples with 100% RGS replacement. The discrepancies in the strength increase rate from 7 to 28 days were observed in some samples which may due to the different surface area and grading of RGS particles change the rate of hydration and porous in mortar.Then, the tensile behaviour of steel-TRM prepared with recycled glass sand with four different mix proportions were experimentally studied. The tensile behaviours of the tested coupons agreed well with the three-phase tensile behaviour. The TRM composite coupons prepared with 100% RGS and 50% lime replacement showed the maximum reductions (73.4%) of average tensile strength compare to the TRM coupons with 50% RGS replacement, which follow the trend of the mechanical behaviour of mortar. Finally, analytical and numerical models considering varying parameters related to the material properties were developed to understand the stress–strain responses and crack patterns of different TRM coupons in tension. Both analytical and macromodelling approaches are able to capture the key global tensile behaviour of TRM as a reasonable fitting was observed with regard to predicting the change in the stiffness in the three stages. The results obtained by micromodelling approach show that TRM coupons with 100% RGS show a larger reduction in the mortar tensile strength and bond fracture energy of the mortar-textile interface. The reason for these reductions might be that higher RGS replacement can be more porous in mortar and the angular edges and rough texture of the RGS, respectively.