Contribution of amorphous material to properties of a laboratory-prepared soil

Abstract

The presence and the importance of amorphous material are becoming recognized in sensitive soils and have been documented in previous studies. In order to further appreciate the specific contributions and influences of the varying composition of amorphous material to a sensitive soil, it is necessary to obtain a soil system where the individual components can be rigorously controlled and subjected to proper scrutiny. To achieve this, the laboratory-prepared soils were obtained by mixing synthesized amorphous iron–silica mixed hydroxides of varying composition with silt-sized particles of primary materials such as quartz, feldspar, or hornblende.In this study the influence of water content and the amount and composition of amorphous material mixed with nonclay minerals on the resultant sensitivity and basic engineering parameters is investigated.The results indicate that Atterberg limits of the laboratory-prepared sensitive soils are dependent upon the composition of amorphous material and that the trends established are similar to those obtained in similar tests on natural sensitive clays obtained from St. Alban, Outardes, and Gatineau. Similarly, the increase in shear strength and soil suction upon aging of the prepared sensitive soil is dependent upon the composition or molar ratio Fe2O3/(Fe2O3 + SiO2) of amorphous material.