Deformational Behavior of Soil-Cement Reinforced with Microfibers

Abstract

This article is part of a study undertaken in the Geotechnics Laboratory of Faculty of Engineering of the University of Porto (FEUP) in partnership with the Federal University of Pernambuco (UFPE) on the deformational behavior of the elastic and plastic phases of a soil-cement reinforced with synthetic microfibers, for use as a primer for low-cost roads. A brief study was first developed on the resistance mechanical behavior of the local soil. Through economic and technical criteria it was established that: cement content (CC) = 5%, maximum dry mass density (γ_d) = 19.8 kN/m³ and optimum water (w_Op) = 11%. After setting the cement content (CC = 5%) the second stage of research began consisting of analyzing the mechanical behavior of the soil-cement mix with added contents of 0.25%, 0.50% and 0.75% of synthetic fibers, 6 mm and 24 mm in length and 18 μm in diameter. At the end of the study, it was found that the 0.75% content of 24 mm fiber offered the highest increase in strength and deformation in the soil-cement-fiber matrix. In the third and last stage of the work, in order to analyze the elastic and permanent deformation of the mixture of soil + 5% cement + 0.75% FibroMac-24, a cyclic triaxial test was performed in a high-pressure chamber. This is a special machine that permitted confining pressure to oscillate parallel with the cyclic distortional axial load. The analysis of the results under these loading conditions helped to extract the following instructions that will be presented in the article: it was found that the soil-cement-fiber mixture presents a reduction in the cyclic deformation modulus when compared to the soil-cement mixture, which also presents higher values ​​of permanent deformation (plastic or irreversible), as it presents less difficulty in relation to the soil-cement mixture.