Experimental and mechanical performance of shotcrete made with nanomaterials and fiber reinforcement

Abstract

Studying the application of nanomaterial in cement matrixes is a new subject which has attracted the attention of researchers. Development of engineered cementitious composite has produced a solution to numerous shotcrete application challenges. In this study, mechanical tests were conducted to evaluate the strength of the concrete modified by fibers and nanomaterials in terms of comparison with conventional concrete and shotcrete.It is included in the application of Nano-Al2O3 and Nano-SiO2, which are some of the cement constituent. With proper homogenization, Nano-Al2O3 acts as filler for improving the pozzolanic reaction in the concrete. Nano-SiO2 particles also prevent the diffusion of external destructive factors into the concrete, thus improving the durability and stability of concrete. On the other hand, application of Alkali Resistant (AR) glass fibers improves the tensile and compressive strengths as well as concrete continuity and also resolves the changes created in mechanical properties of the fibers caused by alkaline concrete environment. Test results revealed that the maximum increase in compression and flexural strengths of modified concrete were 20.6 and 52%, respectively of its optimum compounds for 0.7% glass fiber with 1% Nano-Al2O3 and 1.5% Nano-SiO2, while in the modified shotcrete, these values were increased by 22.9 and 75%, respectively. In addition, application of the mentioned materials led to decrease of penetration depth and water absorption of the modified concrete by 46.78 and 2.5%, respectively, in relation to the conventional concrete. Also, addition of fibers and nanomaterials in shotcrete reduced the effect of cracking due to shrinkage and the modified shotcrete material rebound.