Mechanical Properties of Clay Soil Stabilized Using Sorghum Husk Ash-Blended Cement

Abstract

Clay soils, which possess expansive characteristics, are known to be problematic in construction due to their low strength, poor load-carrying capacity, and high shrink-swell potential. These clay soils undergo substantial volume changes due to variations in moisture content, which can cause instabilities in structures such as foundations, pavements, and other civil constructions. Ordinary Portland Cement (OPC) stabilization has proven to be a popular solution. However, the high cost of production makes it very expensive and less affordable. Therefore, alternative methods, which are cost-effective and more sustainable, require investigation. This paper has investigated the behavior of expansive clay soil stabilized under Sorghum Husk Ash (SHA)-Blended cement with the focus on its Atterberg limits, compaction properties, and California Bearing Ratio (CBR). Soil samples were collected from Nkondi ward in Tharaka Nithi County, Kenya, and sorghum husks were sourced from Mwanyani location, Tharaka Nithi county. The samples were calcined and mixed with 40% cement to make blended cement composed of clinker (40%), calcined clay (20%), sorghum husk ash (20%), limestone (15%), and gypsum (5%). Tests were conducted in the laboratory by using AASHTO T-180 standards. This study investigated the engineering properties of a soil sample through particle size distribution, Atterberg limits, compaction, California Bearing Ratio (CBR), and swell potential tests, following BS 1377 and AASHTO standards. The particle size distribution showed that 62.6% of the fines passed through the 0.075 mm sieve, indicating a predominance of fine particles. Atterberg limits gave a liquid limit of 44.3%, a plastic limit of 28.1%, and a plasticity index of 16.2%, confirming measurable plasticity. Compaction results using AASHTO T-180 revealed a maximum dry density of 1.593 g/cm³ at an optimum moisture content of 21.7%. The CBR test values increased with compaction effort, ranging from 23.8% at low compaction to 88.7% at high compaction, while swell potential decreased from 0.65% to 0.13%. According to the study, sorghum husk ash-modified cement successfully enhanced the engineering properties of expansive clay by improving compaction properties, increasing bearing capacity, and preventing material swelling. This SHA-Blended cement can offer an economical and sustainable substitute to OPC in soil stabilization.