Experimental research into the possibility of using crushed sand-based cement mortar for Micropile grout

Abstract

Currently, the demand for using sand as the construction material in Vietnam is very large. However, the supply of natural sand is very limited compared to the demand, and the natural sand exploitation process also affects the environment. Artificial sand, also known as crushed sand, is a crushed product from natural rocks. The potential for artificial sand production in Vietnam is high since Vietnam’s topography includes 80% of mountains and hills. Micropile piles (diameter £ 300mm) are often used as foundations or to reinforce the foundations of ancient structures that need to be repaired in limited construction space conditions and with little impact on neighboring structures. Micropile mortar is usually manufactured from a mixture of water (N) and Portland cement (X) with the ratio N/X = 0.4 ÷ 0.5, the compressive strength of the mortar at 28 days of age reaches 30 ÷ 40MPa, and the flowability is about 18 ÷ 20cm to ensure workability when pumping. In this study, the authors used artificial sand crushed from granite (Ninh Thuan) to make micropile mortar that meets those set requirements. Results have shown that artificial sand can be used to manufacture micropile mortar with compressive strength at 28 days of age reaching 46.3MPa when the ratio of N/X = 0.43; the flowability of the mortar reached an average of 22.6cm. These physical and mechanical values ​​of mortar manufactured from artificial sand are appropriate for being used as cement mortar for micropiles.