Strength Relationship Equation for Artificially Stabilized Rammed Sedimentary Soils

Abstract

Soils from the superficial layers of the Guabirotuba formation (in Brazil) are problematic due to their expansive and low-bearing capacity. Stabilizing these soils with a calcium-based binder is a technique that must be explored. Therefore, this study aims to determine the mechanical behavior of stabilized sedimentary silts with cement and binder in various conditions. Four types of fine soils were used in deformed conditions. These soils were mixed with cement and compacted to measure their mechanical behavior. The specimens were tested in unconfined compressive and split tensile tests prepared with respect to several molding conditions: the moisture content, the curing period, durability cycles, the dry unit weight, the cement content, the cement type, and the soil type. This study was also carried out to develop a simplified approach to estimating the unconfined compressive strength (qu or UCS) and split tensile strength (qt or STS) of soil-cement or soil-cement–binder mixes. The results further demonstrate the influence of the porosity/volumetric cement index (η/Civ) on the qu- and qt-adjusted two new parameters—bo = 0.174 (dependent on cement) and k = 2.565 (dependent on the type of soil)—proposed herein for all mixtures studied. Using the proposed new parameters, a unique equation was developed to estimate the strength of the compacted blends as a function of the porosity and binder content, with an acceptance of 93% and an error close to 6%.