Influence of Temperature and Duration of Thermal Treatment on Properties of Excavated Soil as Fine Aggregate in Cement Mortar

Abstract

In the interest of utilizing high-plasticity excavation soil as a replacement for fine aggregate in cement mortar, a study on the thermal treatment of soils containing 25% and 40% clay fractions was carried out. A range of tests including thermogravimetric analysis (TGA) and X-ray diffraction (XRD) were conducted to examine the transformation of fines (silt+clay) in soil at temperatures ranging from 200°C to 1,000°C. Thermally treated soils were used as fine aggregate in cement mortar, and properties such as water demand, dry density, compressive strength, and drying shrinkage were studied. The experiments were designed with the parameters treatment temperature and duration using central composite design of response surface methodology. From the test results, it was concluded that thermal treatment helps in transforming clayey soil, even high-plasticity soil, to be used as a suitable fine aggregate material in cement mortar. However, the properties of thermally treated soil highly depend on the clay mineralogy present in it.