Poorly Ordered Silica and Aluminosilicates as Temporary Cementing Agents in Hard‐Setting Soils

Abstract

Abstract Hard‐setting is an important but poorly understood phenomenon in seasonally wetting and drying soils. This study was conducted to determine the role, if any, of chemical cementing agents in a hard‐setting soil. Undisturbed cores from the E horizon of an Aeric Albaqualf were leached in the laboratory with distilled water, 0.15 M ammonium oxalate (pH 3.0 in darkness) and 2 M NaOH/ethylene glycol. The leachates were analyzed for Si, Al, and Fe and the residual materials by infrared spectroscopy. After drying at 40 °C, tensile, shear, and compressive strengths of the cores were determined. All three reagents caused a total loss of tensile strength and decreased shear strength, but had little effect on compressive strength. Amorphous silica is probably the major cementing agent, but the results also indicate that an imogolite‐like aluminosilicate, a feldspathoid mineral, and possibly silica‐Fe complexes may play some part in cementation.