EXAMINING THE SWELLING POTENTIAL OF EXPANSIVE SOIL CONTAINING WASTE PAPER ASH

Abstract

Construction on swelling soil can be a critical problem for civil engineers because of its propensity to volume change. Using waste material to enhance this type of soil would be an ideal choice, as it takes into consideration economic factors and environmental protection. This study investigates the effectiveness of using waste paper ash (WPA) to enhance the swelling soil. The expansive soil in the study was first produced by mixing fine soil with bentonite. Different percentages of WPA, ranging from 0% to 12% of the sample's dry weight, were combined with the soil. A direct method using a single oedometer test was conducted to measure the swelling potential and swelling pressure of the samples. The results showed that both the swelling potential and swelling pressure decreased as the paper ash percentage content increased until a level of 9% of WPA was reached, and after that, both the swelling potential and pressure began to show increases of around 50% and 10% respectively, compared to the values for a  9%WPA content. In addition, consistency limits were conducted for the samples, and similar behavior was observed. Microstructure examinations were performed for the swelling soil and the waste paper ash and for the soil with a 9% content of WPA. It was concluded that an optimum paper ash content of 9% of the soil’s dry weight was required to enhance the expansive soil’s properties. This showed a reduction of 81% and 80% in swelling potential and swelling pressure, respectively.