Evolution of Mechanical Property and Microstructure of Fibre-Reinforced Ultra High Strength Mortar with Desert Sand

Abstract

Previous research showed that the concrete’s strength is obviously decreased when river sand was substituted by desert sand in abundance. In this paper, a new type of fibre-reinforced ultra high-strength desert sand mortar is studied. In the mix design of mortar, low W/B was used to save water. Also, fly ash and silica fume were adopted to partly replace cement, and desert sand was used to completely take the place of river sand. At the same time, steel fibre was used to improve the toughness. The pore structure changes of different desert sand ultra high strength mortar were studied by MIP. SEM and XRD were adopted to study the microstructure and hydration product changes. The results are as follows: the mortar’s mechanical properties are improved when the desert sand content rise. When desert sand was adopted to substitute river sand completely, the mortar’s compressive strength was increased by 36.91%, which reached 149.08 MPa. With the desert sand’s addition, the mortar’s porosity decreases and its pore structure is optimized. Desert sand played an active part in promoting the hydration of mortar, increasing hydration products, densifying the mortar structure and improving the mortar’s mechanical properties..The research in this paper solves the problem that the high-content desert sand mortar’s mechanical properties cannot meet the demand, and provides the actual application of desert sand in mortar a theoretical basis.