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The Effect Of Partial Replacement Of Conventional Fine Aggregate (sand) With Lateritic Soil In The Production Of Sandcrete Bricks
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2.8 Review of Lateritic Soil
The term Laterite could mean bride earth in some Local dialects but the name ‘laterite’ got its meaning from a Latin Word later, meaning ‘bride’ and so relating solely to the use of these in block making. A lateritic soil could them be described as that which has an under developed laterite horizon capable of becoming true laterite given the appropriate condition and sufficient time. (Giorgis et al., 2014) attempted to re-define latrite, by proposing a heal definition and classification based on rock chemistry; basically on the underlying parent rock. This was widely accepted but later criticized strongly by several authors e.g Bourman and Ollier (2002), 2003); Schellmann (2003), Where Bourman and Ollier proposed that the alterite term laterite should have been abandoned. Considering the difficulty and varying opinions as to the term laterite and lateritic soil. The term lateritic soil is defined in this project strictly based on field observation and purpose of this research. Therefore lateritic soil is used to describe the highly weathered tropical or sub-tropical residual soil, which is well graded and usually coated with sesguioxide rich concentrations.
The colour may vary from liver broach to rusty red. Based on this, a laterite could therefore be regarded as fitting exactly the definition although non-residual (transported) soils are often included. High moisture content and temperature cause intense chemical weathering that produces well developed residual soils (Gon Zalez de Valle J.O and Ferrer, 2011). Their geotechnical behavior is controlled by mineralogical composition, micro-fabric and geochemical environmental conditions. Where high iron (Fe) and aluminum (Al) content are present, laterites are formed and when drainage is poor, black cotton soils, may develop, which have high smectite clay content. Alternate wet (raing) and dry season favours the formation of lateritic soil as leaching of the parent rock plane in the rainy season while during the dry season, capillary action transports solutions of leached ions to the surface from where it evaporates with the salts left behind to be washed down the following wet season. Thus the whole zone is progressively deflected of the more mobile element like Na, K, Ca.
2.8.1 Formation of Laterite
Tropicalweathering otherwise referred to as laterization is a prolonged process of chemical weathering which produces a wide variety in the thickness, grade, chemistry and ore mineralogy of the resulting soils (Daivi, et al. 2004). The initial product of weathering are kaolinite rocks called saprolites. A period of active laterization extended from about the mid-tertiary to the quaternary period (35 to 1.5 million year ago) Daivi et al 2004
Laterites are formed from the leaching of parent sedimentary rocks, (Sand stones, Clay, limestone,) metamorphic rock (Schist, Gneiss, Migmatite). Igneous rock (Granites, Basalt, Gabrro, Peridotites) and mineralized pito-oneswhich leaves the more insoluble ions, predominantly iron and aluminum (tardy, 2000). The mechanism of leaching involve acid dissolving the host mineral lattice and sulphate of iron, aluminum and silica under high temperature condition of humid subtropical monsoon climate (Hill, et al, 2000). An essential feature for the formation of laterite in the repetition of heat and dry season. The ions form soluble salt compound which dry on the surface. These salt are washed away during the heat season (Yamaguch, 2010). Laterite formation isESfavorable in low topographical relief of gentle crust and plateaus which prevent erosion of the surface cover Davi, et al, 2004. The reaction one where rock are in contact with water from the lowest to the highest water table level is progressively depleted of the easily leached ion of sodium potassium, calcium and magnesium. A solution of these ion can have the correct pit to preferentially dissolve silicon oxide rather the aluminum oxides and iron oxides (Yamaguchi, 2010). The transformation of rock into laterite proceed in general gradually as indicated by the steady increase of iron and decrase of silicon in laterite profile about the parent rock
It goes without saying that the final product of weathering cannot be called laterite. They also form in moderate climate and are essentially kaolinized rocks still slowing the structure of the rock. They are called saprolites in which iron is not as strongly concentrated as in laterite. Some saprolite stone due to finely disseminated haematite a deep red colour and are sometimes erroneously considered as laterite. Lateritic sediment of older epochs can be over printed by younger laterite weathering. Complex lateritic occurrences are grouped as exolatentes, false laterites and laterite derivatives facies. They are relevant in regional studies but not for a general understanding of the laterization process. This is equally true for those surface layers above autochonus laterites, locally separated by a stone line. They commonly show a sapeolitic composition with higher sio2 content and are deposited on the laterite surface. Very often termites carried this material upward from deeper horizon. In other instances zirconium content in the surface horizon of laterite (Nidee limonite) above ultramafic rocks indicates an admixture from one area with other parent rock (scheumann, 2008). A three- step model of tropical weathering, depending on the intensity of the weathering process was suggested by schellmann, 2008. As follows
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ABSRACT - [ Total Page(s): 1 ]ABSTRACT WILL BE HERE SOON ... Continue reading---
CHAPTER ONE - [ Total Page(s): 2 ]CHAPTER ONE1.0 Introduction Lateritic soils are formed in hot, wet tropical regions with an annual rainfall between 750 to 300mm, (usually in areas with a significant dry season) on a variety of different types of rock with high iron content. The location on the earth, that characterize these conditions fall between latitude 35oS and 35oN (Person, 1970).Laterisation is the removal of silicon through hydrolysis and oxidation that result in the formation of laterite and lateritic soil ... Continue reading---
CHAPTER THREE - [ Total Page(s): 7 ]ProcedureAbout 200g of soil sample was passed thoroughly with distilled water to form a uniform paste. A portion of the paste was placed in a brass trough bar (linear shrinkage trough device). The surface of sample was leveled and smoothened off to the brass of the trough bar and the trough was then placed in an oven for 24 hours at temperature of about 105°C. The initial length of the trough bar filled with the soil sample was taken. After 24 hours, the trough bar was brought out of the oven ... Continue reading---
CHAPTER FOUR - [ Total Page(s): 15 ]PERCENTAGE OF STABILIZER ... Continue reading---
CHAPTER FIVE - [ Total Page(s): 1 ]CHAPTER FIVE5.0 CONCLUSIONS, REFERENCE AND RECOMMENDATION. 5.1 Conclusion. Tests
have been conducted to evaluate the suitability of lateritic soils
along Asa dam area Ilorin kwara state and its effect on the strength of
sandcrete bricks when used to replace the conventional fine aggregate,
the following conclusions can be drawn from the analysis of the results:
I. The use of lateritic fine as a partial replacement has a significant influence on the engineering pro ... Continue reading---
REFRENCES - [ Total Page(s): 3 ]REFERENCESAdam, E. A. (2001): Compressed Stabilised earth block manufactured in sudan, A. Publication for UNESCO (online) Available from http://unesdoc.unesco.org.Adepegba, D.A. (1975). “Comparative Study of Normal Concrete which contains Laterite Fines instead of Sand†Building Science; 10:135-41.Agbede, I.O. and Manasseh, V. (2008): use of cement sand admixture in lateritic brick production for low cost housing Leonardo electric Journal of practices and technology, 12, pp163-174.Ak ... Continue reading---
