Modern civilization and industries are a major cause of soil contamination which is because of acidic or alkaline pollutions which tends to alter the pH of the soil. Soil acidity is one of the major problems in the world which may affect the geotechnical properties and behaviour of the host soil. Temperature is also an important factor that needs to be considered; it increases the physicochemical reaction of the contaminated soil. Lateritic soils are rich in sesquioxides that provide stability in the cementation of aggregates. They are used in several geotechnical constructions; hence, it is important to study how the behaviour of the soil would be after a change in pH. Thus, this study attempts to make a better understanding of the influence of acidity and temperature on the geotechnic...[ Read more ]

Modern civilization and industries are a major cause of soil contamination which is because of acidic or alkaline pollutions which tends to alter the pH of the soil. Soil acidity is one of the major problems in the world which may affect the geotechnical properties and behaviour of the host soil. Temperature is also an important factor that needs to be considered; it increases the physicochemical reaction of the contaminated soil. Lateritic soils are rich in sesquioxides that provide stability in the cementation of aggregates. They are used in several geotechnical constructions; hence, it is important to study how the behaviour of the soil would be after a change in pH. Thus, this study attempts to make a better understanding of the influence of acidity and temperature on the geotechnical properties, compressibillity and shear behaviour of lateritic sandy clay.

A series of laboratory experiments were conducted to study the physicochemical and geotechnical index properties, soil microstructure, compressibility and shear behaviour of the untreated lateritic soil (UL), acid treated lateritic soil with hydrochloric acid of pH 3 at room temperature (AL) and acid treated lateritic soil pH 3 at a temperature of 60^oC (AHL). The treatment process was carried out at 60^oC (AHL) to simulate the high soil temperature typical of Africa. The following tests were carried out to study the influence of acid treatment on lateritic sandy clay; X-Ray diffraction (XRD) and X-Ray fluorescence (XRF) to quantify the chemical composition and mineralogy, physical properties of the soil such as: Atterberg limits, compaction characteristics, particle size distribution. The soil microstructure was observed using scanning electron microscopy (SEM) and one-dimensional consolidation tests was performed using the conventional oedometer. Then, isotropic compression and consolidated undrained (CU) tests.

The results showed that there was an increase in fine contents after acid treatment as the pH changed from 6.5 to 3. Both the liquid limit and plasticity index of the soils increased due to the increase in fine content and surface area of the acid treated soils. A decrease in compressibility was observed after acid treatment for both the one-dimensional and isotropic compression tests. This was confirmed by the SEM results; the decrease in compressibility is attributed to the reduction in soil aggregate and the fine particles tend to occupy the large pores. This was confirmed by the SEM results. It is found that shear strength of the acid treated soil subjected to temperature of 60℃ was lower compared to UL and AL. The AL and AHL specimens did not reach critical state.