Improvement of Sub-Base of Roads by Chemical Admixtures and Organic Materials

Abstract

One of the aspects of increase of earlier damage and failure of traffic load, especially in clayey regions, is the deficiency of pavement subgrade. To prevent such damage, strengthening of the pavement by improving the subgrade layer is essential. Many investigators have carried out research on the subgrade layer, especially when containing clay particles, using several types of additives (stabilizers). Soil Stabilization is a method of improving the engineering properties of soil and therefore making it more stable. Generally, stabilization includes pre-consolidation, compaction and numerous other similar methods. However, stabilization is usually related to the processes which modify the soil composition itself for enhancement of its properties. Soil stabilization of pavements is usually designed based on the assumption that specified levels of quality will be achieved for each soil layer in the pavement system. Each layer must resist shearing within the layer, avoid excessive elastic deformations that would result in fatigue cracking within the layer or in overlying layers, and prevent excessive permanent deformation through densification. Engineers are responsible for selecting or specifying the correct stabilizing method, technique, and quantity of material required. Usually, the technology provides an alternative provision structural solution to a practical problem. The simplest stabilization processes are compaction and drainage. The other process is by improving gradation of particle size and further improvement can be achieved by adding binders to the weak soils. This study showed that lime activated by sodium chloride in combination with sugar cane ash could be effectively used to improve soft clay with low soaked CBR value and high plasticity. Therefore, from the environmental point of view, it was recommended that sugar cane ash can partially replace lime in clay stabilization to form material with cementitous properties