Preparation and flexural fatigue resistance of self-compacting road concrete incorporating nano-silica particles

Abstract

In this study, the mix proportion of self-compacting road concrete with ternary cementitious materials was optimized by incorporating nano-silica particles to improve its flexural fatigue performance. The filling property and compressive strength were selected as evaluating indicators to design L9(33) orthogonal test, and then four kinds of mix proportions were selected to prepare the nano-modified self-compacting concrete (SCC) according to the results of grey relational analysis and comprehensive weighting method. The four-point flexural fatigue tests were conducted to establish the probabilistic fatigue equations of nano-modified SCC based on the two-parameter Weibull distribution with survival rates of 50% and 95%, respectively. The modification mechanism was revealed with the help of scanning electron microscopy and X-ray diffraction phase analysis. The results indicate that the optimal mix proportion of self-compacting road concrete could be obtained when nano-silica accounts for 1% of the mass of cementitious materials. The specimens with 1% nano-silica particles showed the best flexural fatigue performance, with the reduction factor of flexural strength increased by 1.5%–5.0% and the sensitivity of fatigue life to the stress levels decreased by 2.1%–9.7% at survival rate of 50%. The nanoparticles provided a physical filling effect and facilitated the formation of low-density calcium silicate hydrate gel, filling the internal micro-pores to make the structure more compact. Nano-silica improved the flexural fatigue performance of self-compacting road concrete to a certain extent.