Microstructural properties of lime stabilized naturally occurring acidic soil

Abstract

Natural Acid occurring soils are very common in regions with high rainfall. KwaZulu-Natal (South Africa) is no exception to this. Agricultural wise, these soils are a major cause of poor yields of crops and vegetables, limiting plant growth by stunting root development and thereby the uptake of water and nutrients. Mixing lime into the topsoil is one of the effective ways of dealing with soil acidity problems. Engineering wise, the use of lime to soil is associated with weak, unstable or unsuitable soils. It is often a norm that when natural or imported natural occurring soil is encountered during road construction for base courses, the need to intervene in improving the structural stability of such soils arises. One of the intervention which has been used and still in use involves the application of lime to soil so as to enhance the stability in the soils.

An experimental program was undertaken to investigate the effects of hydrated lime in studying the microstructural of natural occurring acidic soil samples. Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) tests were used to indent chemical composition and structure of the three soil samples treated with lime. Three (3) natural occurring acidic soil samples were collected at three different locations and treated with lime contents (i.e. 2%, 4%, 6%, 8% and 10% by weight of soil). Further tests such as gradation & consistency limits, were conducted.

The test results indicated that the inclusion of lime to the three soil samples changes the pH (increases) of the tested soil (acidic). SEM and EDS graphics showed that lime treatment changed significantly the soil fabric depending on curing time and water content, this time being 7 days of curing.