Expansive soil stabilised by calcium carbide residue–fly ash columns

The volumetric changes in expansive soils due to variations of seasonal moisture are the cause of many problems in structures. This paper reports laboratory oedometer test results performed on expansive soil stabilised by calcium carbide residue–fly ash (CCR–FA) columns with different percentages of CCR and FA, on seven columns of different orientations and diameters. A significant reduction in the swell potential and swell pressure was observed, 62% (CCR:FA = 20:80) and 68% (CCR:FA = 20:80), respectively. The influence of the binder content on the properties of the treated soil was interpreted by means of particle size distribution, mercury intrusion porosimetry, scanning electron microscopy and x-ray diffraction analyses. Soil parameters such as particle size, pore size, soil texture and amount of montmorillonite underwent a considerable change that can be attributed to the migration of the binder along with water to the surrounding soil columns. Soil strength development will be fundamental for further study.