Mechanical behavior and durability of a typical frictional cohesive soil from Rio Grande do Sul/Brazil improved with Portland cement

Abstract

Lateritic soils are typical of tropical and subtropical climate regions, whose coverage is wide in Brazilian territory. These soils are formed by the leaching of oxides and silicates and are found in unsaturated conditions with a high void ratio due to the presence of macropores and micropores. As a result, the soil has drained behavior and high compressibility. Given these peculiarities, the use of cementing agents can be a suitable solution to promote modifications on the soil’s physicochemical properties to affect bearing capacity and stiffness. This study focuses on the mechanical behavior of typical cohesive frictional soil in the city of Passo Fundo (Southern Brazil) improved by Portland cement of high initial strength (Type III) based on the adopted amount of cement C (%) and γd. Initially, unconfined compression strength tests (qu) were performed for cement contents of 3%, 6%, 9%, and 12%, and γd equal to 16.4 kN/m3, 15.4 kN/m3, 14.4 kN/m3, 13.6 kN/m3, and 12.7 kN/m3, followed by ultrasonic pulse velocity tests to determine the G0. Then, tensile tests were performed through Splitting Tensile Test (qt) considering γd of 16.4 kN/m3, 15.4 kN/m3, and 14.4 kN/m3 for cement contents of 3%, 6%, 9%, and 12%. Finally, the improved soil was studied using durability tests under wetting/drying conditions with γd of 16.4 kN/m3, 15.8 kN/m3, 14.5 kN/m3 and cement content of 3%, 6%, 9%, and 12%. The results indicate that C and γd are sufficiently significant factors in understanding soil’s behavior regarding wetting/drying of the mixtures, in that order. Finally, normalized curves of qu, qt, G0 and LM and VR were developed as a function of the adjusted η⁄Civ for practical purposes of dosages for ground improvement.