Simple Method to Identify Marl Soils

Abstract

An experimental investigation proposed a simple, practical method to identify marl soils in the laboratory and to classify the soils. The percentage of calcium carbonate (CaCO3) of the soil was determined with three methods: (a) thermogravimetric analysis (TGA), (b) sequential loss on ignition (LOI), and (c) chemical reaction following ASTM C25. The sequential LOI test has the advantage that both organic and CaCO3 content of the soil can be determined with a conventional furnace. X-ray diffraction, pH, and Atterberg limits tests were also conducted. The percentage of CaCO3 determined from the sequential LOI tests agreed well with those from the TGA tests and from the chemical tests. No correlation was found between the percentage of CaCO3 and organic content in the soil. As the organic content of the soil increases, the liquid limit increases and the plasticity of the soil increases. As the CaCO3 content of the soil increases, the liquid limit of the soil decreases and the soil becomes less plastic. The geotechnical engineering properties of marl soils depend on organic content and CaCO3 content, and so the soils should be classified according to both organic content and CaCO3 content.