Enhancing rubber concrete with supercritical fluid-assisted Nano-SiO2 embedding and high-temperature stirred waste rubber

Abstract

Using waste rubber particles(WRP) to replace fine aggregates in producing rubber concrete promotes recycling and reduces natural sand consumption, which is crucial for sustainable resource use. Unfortunately, rubber's low rigidity and poor interface bonding with the concrete matrix cause a significant strength loss. Many have done surface treatments on the particles, yet these often result in low efficiency and insignificant strength increases. This paper introduces a novel approach: employing supercritical fluid (CO2) assisted shearing to embed nano-silica and high-temperature stirring for pre-treating rubber particles. This improves the rigidity, removes impurities, and enhances surface smoothness. Thermal Gravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy(FT-IR), Scanning Electron Microscope(SEM), and Energy-Dispersive X-ray Spectroscopy(EDS) tests on treated particles show SiO2 embedded inside, clean surfaces, and hard oxide film formation. Rubber concrete prepared using this shows obvious improvement in mechanical properties compared to untreated rubber particles, with 7-day and 28-day cubic compressive strengths increasing by 74.9 % and 54.8 %, respectively. These increases outperform most reported in the literature.