Statistical Analysis of the Influence of Curing Time and Temperature on Compressive Strength of Sandy Soil Stabilized with Sustainable Binder

Abstract

Abstract Rice husk ash (RHA) is a by-product of the incineration of rice husk, a process whose objective is the generation of thermal and electrical energy. Carbide lime (CL) is a residue of acetylene gas production. Agricultural-industrial wastes, like RHA and CL, have great potential applications in earthworks, mainly in the regions where these residues are produced. This research evaluates the potential use of RHA mixed with CL as a binder used to improve strength properties of sandy soils, substituting portland cement. Different curing temperatures (23°C and 40°C) and curing periods (7 and 28 days) of the compacted sandy soil-RHA-CL blends were evaluated to determine the importance of such changes on the strength of the blends. Studies have been carried out to quantify the unconfined compressive strength (qu) as a function of a novel index called porosity/binder. The aim of this index is to measure the influence of porosity and binder content on blends’ properties, considering the combination of the amounts of RHA and CL as the binder. The results show that higher values of qu are obtained with the reduction of porosity and with the increase of binder content. Curing temperature acts as a catalyzer and accelerates pozzolanic reactions between RHA and CL. For the purpose of verifying the effect of the investigated controllable factors—γd, RHA, CL, and curing type—in the response variable qu, an analysis of variance was performed. Based on that, it was possible to verify that the types of curing during 28 days at 23°C and for 7 days at 40°C are statistically equivalent. It increases the possibility of choice for engineering design because these results mean that the engineer may choose an appropriate curing period and temperature in accordance with project requirements and average temperatures in the site construction.