LATERITE SOIL

The behavior of shallow foundations constructed on lateritic soils is of significant importance in tropical regions where these soils occur extensively and are commonly used for civil engineering works. Lateritic soils are highly variable in nature, and their engineering performance is strongly influenced by factors such as mineral composition, moisture content, degree of compaction, and environmental conditions. This variability often leads to challenges in predicting foundation performance and ensuring structural safety. This study investigates the behaviour of shallow foundations on lateritic soils through a combination of field and laboratory investigations. Field studies include soil sampling and in-situ tests to assess the natural state of the lateritic deposits. Laboratory tests are conducted to determine the index properties, compaction characteristics, shear strength parameters, and bearing capacity of the soils. Model and empirical methods are employed to evaluate the load-bearing capacity and settlement behavior of shallow foundations under different soil conditions. The results of the study establish relationships between key soil properties—such as moisture content, density, plasticity, and strength—and the performance of shallow foundations. The findings provide valuable insight into the load-bearing behavior of lateritic soils and highlight the importance of proper soil characterization in foundation design. The study aims to contribute to safer and more economical design practices for shallow foundations in lateritic soil environments, particularly in tropical regions.

The behaviour of shallow foundations constructed on lateritic soils is of significant importance in tropical regions where these soils occur extensively and are commonly used for civil engineering works. Lateritic soils are highly variable in nature, and their engineering performance is strongly influenced by factors such as mineral composition, moisture content, degree of compaction, and environmental conditions. This variability often leads to challenges in predicting foundation performance and ensuring structural safety. This study investigates the behaviour of shallow foundations on lateritic soils through a combination of field and laboratory investigations. Field studies include soil sampling an in-situ tests to assess the natural state of the lateritic deposits. Laboratory tests are conducted to determine the index properties, compaction characteristics, shear strength parameters, and bearing capacity of the soils. Model and empirical methods are employed to evaluate the load-bearing capacity and settlement behaviour of shallow foundations under different soil conditions. The results of the study establish relationships between key soil properties—such as moisture content, density, plasticity, and strength—and the performance of shallow foundations. The findings provide valuable insight into the load-bearing behaviour of lateritic soils and highlight the importance of proper soil characterization in foundation design. The study aims to contribute to safer and more economical design practices for shallow foundations in lateritic soil environments, particularly in tropical regions.

The lateritic soils show a great variation in their properties as per their geological parent, weathering and mineralogical structure resulting in natural variation even in the relatively small geographical regions. Such variability presents serious difficulties to the engineers in determining their behaviour as well as designing the necessary compaction specifications. This study was intended to examine the impacts of different compactive efforts on lateritic soil engineering properties and to see how best they can be utilized in a civil work activity, using Oluku Borrow Pit and Blocks of Flats Gully Site in Benin City as the case study. Two samples of bulk laterite soil samples were collected at the two sites, dried in the air, ground and sent to the lab. The preliminary index tests such as particle size distribution, Atterberg limits, natural moisture content and specific gravity were conducted in order to classify the soils. Standard Proctor, West African Standard (WAS) and Modified Proctor methodologywere used to conduct compaction tests to measure the Maximum Dry Density (MDD) and Optimum Moisture Content (OMC). To determine the strength properties of the compacted soils, California Bearing Ratio (CBR) tests were later conducted in the soaked and unsovid states.The findings indicated that the maximum dry densities and the optimum moisture contents of both soils were increased by the increase in the compactive effort. Using the West African Standard compactive effort, optimum moisture content in the form of the West African Standard was a maximum of 10 per cent, with a maximum of 2.08 Mg/m3 dry density. The Oluku Borrow Pit soil, which had a lower content of fines (about 4.95-5.53% less the 0.075 mm sieve at shallow depths), presented a better performance with unsoaked CBR ranging between 28% at the shallow depths of compaction under the Modified Proctor compaction, whereas the soaked CBR was between 4-6%. Conversely, the Gully Site soil, which contains more fines (30 to 44 percent passing 0.075 mm sieve) registered lower unsoaked values of CBR of 2 to 4 percent and soaked values below 1 percent, which means that it is highly sensitive to moisture.