Evaluating the durability of expansive subgrade soils stabilized with molasses and cement.

Abstract

Pavement construction tends to be relatively expensive in areas where expansive clay forms the bulk of the alignment of soil. This is due to the extra costs incurred to improve such a subgrade. Unsuitable soils for road construction can be improved by a process called stabilization. This is the addition of additives to the soil in order to improve its engineering properties. The most common means of stabilization is by use of lime and cement. Due to the various negative effects of the use of cement, studies have been carried out to identify more environmentally friendly and cost-effective additives that can be used to partially replace it, one of which is molasses. However, these studies have been heavily focused on index and compaction properties. This study evaluated the durability of expansive subgrade soil stabilized with 8% cement + 4% molasses, 4% cement + 4% molasses and 13% cement. Separate soil samples were stabilized with the different cement-molasses ratios, which were then compacted at their optimum moisture contents to their maximum dry densities and were subjected to the wetting and drying of compacted soil-cement mixtures ASTM D559. This tested their resistance to abrasion which is one of the factors that affects durability. The rate of mass loss of the sample stabilized with 13% cement only was 4.1% per cycle. The sample stabilized with 4% cement + 4% molasses failed during the third cycle with an estimated rate of mass loss at 18.2% per cycle whereas the sample stabilized with 8% cement + 4% molasses failed during the fifth cycle with an estimated rate of mass loss at 10.8% per cycle, which reduced the former by 40%.