Assessment of Strength and Curing Time of Enzyme Improved Mountainous Soils for Use as G30 Material for Budibugyo Area

Abstract

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, cement or fly ash. These means of stabilization have proved to be expensive and are not environmentally friendly. In addition, these traditional/ conventional means of stabilization are not effective in stabilizing the soils in the project area since these soils have a high cation exchange capacity. These concerns have led to the use of non-traditional stabilizers such as enzymes. By definition, an enzyme is an organic catalyst that speeds up a chemical reaction, that otherwise would happen at much slower rate, without itself becoming a part of the end product. This study examined the use of enzymes as stabilizers and was aimed at determining the effectiveness and suitability of using two enzymes code named; ENZ I and ENZ II in improving the properties of inferior cut materials on Bundibugyo roads for G30 quality standard. Representative samples were extracted and taken to the laboratory. The research was mainly based on laboratory testing of plasticity and strength parameters of the soils treated with the enzymes and curing them over a period of 28 days. Results show that indeed the enzymes alter the properties of the soil. ENZ I and ENZ II both lead to a reduction in PI of the soils being tested. ENZ I has the greatest effect on California Bearing Ratio by increasing it by 65.3% whereas the behavior of ENZ II is not consistent over the 28 day curing period for the samples tested. ENZ I can therefore be recommended for road projects of low design class and with soils of medium range properties. Curing has an effect on the performance of the enzymes. The evidence of this is exhibited in the improvement of the engineering properties of the soils to meet G30 quality standard as the curing period increases.