A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology

Thesis (M. Eng.) - Asian Institute of Technology, 1982

When improving the unsatisfactory properties of the soil for construction, the effective and economical stabilization of the soil is important. Being a waste product of thermal power plants, flyash can be obtained very cheaply. This investigation compares the strengths obtained from different kind of additives, that is, cement, lime, lime and flyash, gypsum and flyash, and flyash alone. Compaction was carried out by using the Harvard Miniature Compaction Apparatus and .strengths were measured by unconfined compression tests. The amount of additives, the type of stabilizer, and the different curing times for the strength development of the treated soils are reported. Results show that the strength obtained in the cement-soil mixture is higher than that in the other additives mixtures with a small amount of additives. The strength was considerably increased by adding flyash to the lime-soil mixture. It is noticeable that the strength obtained in the flyash-soil mixture is, after a certain curing time, higher than that in the other mixtures which are treated with lime or a small amount of cement. In the present investigation only one commercial type of gypsum was used. It was found from the study that gypsum is not suitable for use with this type of flyash-soil mixture. Generally the strength of stabilized soil is increased by increasing the amount of additives and lengthening the curing time.