The purpose of stabilizing -a soil is to alter its physical properties,increase its strength and increase its durability in order to provide a satisfactoryfoundation material. The admixtures most commonly used today in roadconstruction throughout the world are cement, lime, asphalt and sand. Cementappears to be most common additive used to date in Africa and South AmericaLime has been used as well, but not as commonly as cement. The use of asphalthas been limited to lateritic soils of a sandy nature. Stabilization byadmixture of sand has been investigatedThere has been a certain amount ofcontroversy between those advocating stabilization with cement and thoseadvocating stabilization with lime. This is true in temperate climates involvingboth residual and transported soils.
It is also true in tropical climates wherethe soils are mostly residual. Those that believe only in cement stabilization statethat there is little in tropical residual soils with which the lime can react,and unless there are clay-lime reactions, there is no benefit in adding lime.Those who believe in lime stabilization state that most clayey materials aremore effectively stabilized with lime than cement. There are also those who believein a combination of both lime and cement for tropical red soils. Studies havefound many highly plastic soils which do not increase in strength upon theaddition of lime but which always show a reduction in plasticity. The soilsbecome more friable and easier to mix creating ideal soils for cementstabilizationKreijger stated that we are the one who willbe responsible when making choices of the materials to be used in the projectand the one to take the ecological and social consequences of our decision.
Inother words, when choosing a materials for construction we must also consideron its effect environmentally,technically and economically. Ilorii and Udo (2015) The geotechnicalproperties of an A-7-6(8) soil that exert great influence on the behavior of ahighway pavement when the soil is used as subgrade, subbase andbase were investigated when mixed with various percentages of saw dust ash. Themixture improves the properties of the virgin soil at optimum percentage of 12.At this level of mixture, an increase in strength of the soil up to four timesthat of the native soil as indicated by Unconfined compression test, a lessexpansive soil as indicated by plasticity index of the resulting mixture, andlower values of plastic limit which signifies stale soil.
SDA can be used toreduce the Plasticity Index values of expansive soil, which are often a problemin road and building engineering construction