Classification of Expansive Clay Soil Samples

Abstract

The aim of the study is to evaluate and classify samples of natural swelling soils and after their treatment based on the results extract from previous laboratory tests. The results of Atterberg limits tests (liquid limit and plasticity index) and the particle size distribution of the soil (sieve analysis test and hydrometer test) were carried out on original soil samples. The Atterberg limits test was also conducted after adding construction waste powder in inconsistent weight percentages of 25%, 50%, and 75%. Several classifications were applied to both original and improved soil samples according to the classification standards for swelling soils from charts and model curves derived from soil mechanics research studies. These classifications particularly base on Atterberg limits (liquid limit and plasticity index), clay content, and clay activity. This study focuses on comparing the classification results of original clay samples and after adding different proportions of the improved material. The classification results for soil A without additives, according to various charts, curves, and classification models, were mostly classified as (very high). After adding 25% construction waste powder, there was a significant improvement in its swelling degree (medium). As for the rest samples B, C, and D their classification was close to a (very high) index in their natural state. This is due to the similarity of the Atterberg limits results, sieve analysis test, and sedimentation analysis. After adding 75% of construction waste powder to these samples, the liquid limit and plasticity index decreased by up to 50%, and consequently, the swelling index improved to (medium).