Stabilization ofLaterite soils: A Literature Review Soil materials are a vital element andconsidered to be one of the important parameters in all civil engineeringdesigns. In most parts of the tropical areas of the world, lateritic soils areextensively encountered. Clay is an important component of lateritic soils,especially when assessed for civil engineering purposes (Townsend, 1985).
“Laterite” from the Latin word “Later” meaningbrick can also be used to stabilize the soil. It is a soil layer that is richin iron oxide, reddish-brown in colour and mostly developed in humidsubtropical and tropical climate (The Editors of Encyclopædia Britannica, 1998). ( Adebisi, Adeyemi, Oluwafemi, & Songca, 2013) Worked on some index properties andcrushing strength of three south western Nigeria lateritic clay deposits withthe aim of seeing how the materials could be used for bricks. The result oftheir findings showed that firing increases the strength tremendously. Researchon this type of soil has been tested in other countries to help stabilize thesoil aggregates. Therefore, it is also possible in using this type of soil whenmaking bricks. The following review of literature confirms a laterite soil canstabilize the soil when making bricks as supported by the related reviewarticles and applied in the construction industry. Importance ofstabilization on Laterite SoilThepurpose of stabilizing a soilis to alter its physical properties, increase its strength and increase itsdurability in order to provide a satisfactory foundation material.
Theadmixtures most commonly used today in road construction throughout the worldare cement, lime, asphalt and sand. Cement appears to be most common additiveused to date in Africa and South America Lime has been used as well, but not ascommonly as cement. The use of asphalt has been limited to lateritic soils of asandy nature. Stabilization by admixture of sand has been investigated. ImprovingLateritic Soils using different stabilizersThere are many ways in stabilizing the laterite soil. Itresponds to cement stabilization and, in some cases, lime stabilization (Townsend, 1985).The techniques of soilstabilization can be categorized into a number of ways such as consolidation,vertical drains, vibration, surcharge load, admixtures, grouting andreinforcement and other methods (Ravichandran et al., 2016).
( Ayeni, 2016) Noted the addition of limestone willimproved the shear strength of soil. However, while considering potential usesof soil samples added with lime, the effects of wetting cannot beoveremphasized. He shows that when added with up to 6%of limestone ash there is an increase in California bearing ratio but accordingto ( Ilori & Udo, 2015) it is possible by adding 5% of lime materials. (Marathe, Kumar , & Avinash, 2015) Suggests the sametrend can also be seen for soil with 3%of cement. While in the study ( Ilori & Udo, 2015) laterites soilhaving properties of A-7-6(8) wasqualified and suitable to use as a subgrade, sub base and base material in ahighway construction when added with saw dust ash in various percentage. For road construction, it recommends 7% cement for base materials, 5%lime for sub-base materials and 18% rice husk ash for sub-base materials (Rahman, 1996). However, there was few who focusedon applying laterites soil on bricks.
Soil data access can be used to reducethe Plasticity Index values of expansive soil, which are often a problem inroad and building engineering construction. Therehas been a certain amount of controversy between those advocating stabilizationwith cement and those advocating stabilization with lime. This is true intemperate climates involving both residual and transported soils. It is alsotrue in tropical climates where the soils are mostly residual. Those thatbelieve only in cement stabilization state that there is little in tropicalresidual soils with which the lime can react, and unless there are clay-limereactions, there is no benefit in adding lime. Those who believe in limestabilization state that most clayey materials are more effectively stabilizedwith lime than cement. There are also those who believe in a combination ofboth lime and cement for tropical red soils. Studies have found many highlyplastic soils which do not increase in strength upon the addition of lime butwhich always show a reduction in plasticity.
The soils become more friable andeasier to mix creating ideal soils for cement stabilization. PlasticityIndex, Compressibility and Shear strength in laterite soilThere are lot of research aboutlateritic soil but did not focused so much on the plasticity index and compressibilityof the material (BADMUS, 2010) .The Unconfinedcompressive strength (UCS) test results showed that there was decrease in UCSstrength of soil sample as the curing period increases (Marathe, Kumar , & Avinash, 2015) and when cement isadded to soil sample the UCS strength increases tremendously.
IJIRSET explainedas the time progresses, formation of dicalcium silicates takes place due tohydration of cement because presence of dicalcium silicates is responsible forstrength at later stages.( Horpibulsuka, Suddeepong, Chamket, & Chinkulkijniwat, 2013) Procedure which includes fieldcompaction control and the material selection was recommended. Uses of Laterites in EngineeringConstructionFromecological and engineering perspectives, Lateritic soil can be used forlandfill sites. (Horpibulsuk, 2013)Based from his data that has been tested, it can also be used for roadembankment and rural and highway pavement. ( Ayeni, 2016) The concept of chemical stabilisationof Laterite soil using different percentages of limestone ash have also beenevaluated for road construction. The Relations between geotechnical propertiesof soils help the researchers in designing different civil engineeringstructures.
It was also qualified and suitable to use as subgrade, sub base andbase material in a highway construction when added with saw dust ash in variouspercentage ( Ilori & Udo, 2015). ( Ayeni, 2016) Noted the addition of limestone willimproved the shear strength of soil. ConclusionIn this literature review, most of thestudies on properties of lateritic soils do not pay attention so much on themoisture content, the wet and dry-densities and its porosity. Furthermore, Differentresearchers indicate its respective materials for chemical stabilization anduse various percentages that will be compatible to improve the shear strength,CBR and other requirements needed in their research. Questionsfor future research:Mostly of the lateritic soil were oncompressed earth blocks (CEB) and few are on bricks. Whatif we use lateritic soil that we see in our backyard in making bricks? Wouldthe properties of this soil no different?Untilwhat percentage will be needed to obtain the desired result?Wouldthe ordinary bricks the same as laterite bricks?