Effects of Diethanolamine (DEA) and Glass Fibre Reinforced polymer (GFRP) on setting time and mechanical properties of shotcrete

By now, various accelerators have been used to accelerate the chemical reactions between cement and water to achieve a desired strength. This study investigates the effects of diethanolamine (DEA) as a less corrosive accelerator on the setting time and mechanical properties of fibre reinforced shotcrete (FRS). Glass fibre reinforced polymer (GFRP) was also used to improve the flexural and tensile strengths of shotcrete. In total, 76 different mix designs were prepared and tested to determine the setting time, flexural and tensile strength of shotcrete. The mixes were designed based on three influential parameters including GFRP, water/cement (w/c) ratio and the amount of DEA. According to the results, the flexural and tensile strengths of all specimens increased by adding 0.5% of the weight of GFRP. However, both tensile and flexural strengths showed an insignificant reduction by adding DEA to the mixes. The tensile and flexural strengths of specimens decreased slightly by adding DEA in the presence of GFRP. At a certain amount of DEA, the setting time increased twice with increasing the w/c ratio. The results showed a reduction in the shotcrete strength by using DEA. Thus, in the case where both the setting time and shotcrete strength are of great importance, the optimal DEA level is close to 0.3% of the dry weight of cement and 0.5% GFRP. •A significant decrease in the setting time of mixes at a water/cement ratios less than 0.35.•An increase in the setting time with increasing GFRP level in mixtures with different water/cement ratio.•The tensile and flexural strengths of shotcrete specimens decreased by incorporating DEA.•0.3% and 0.5% of cement dry weight are optimal amounts of DEA and GFRP when setting time and flexural strength are important.