A review of the use of lateritic soils in the construction/development of sustainable housing in Africa: A geological perspective

The transportation infrastructure, including low-volume roads in some regions, needs to be constructed on weak ground, implying the necessity of soil stabilization. Untreated and cement-treated lateritic soil for low-volume road suitability were studied based on Malaysian standards. A series of unconfined compressive strength (UCS) tests was performed for four cement doses (3%, 6%, 9%, 12%) for different curing times. According to Malaysian standards, the study suggested 6% cement and 7 days curing time as the optimum cement dosage and curing time, respectively, based on their 0.8 MPa UCS values. The durability test indicated that the specimens treated with 3% cement collapsed directly upon soaking in water. Although the UCS of 6% cement-treated specimens decreased against wetting–drying (WD) cycles, the minimum threshold based on Malaysian standards was still maintained against 15 WD cycles. On the contrary, the durability of specimens treated with 9% and 12% cement represented a UCS increase against WD cycles. FESEM results indicated the formation of calcium aluminate hydrate (CAH), calcium silicate hydrate (CSH), and calcium aluminosilicate hydrate (CASH) as well as shrinking of pore size when untreated soil was mixed with cement. The formation of gels (CAH, CSH, CASH) and decreasing pore size could be clarified by EDX results in which the increase in cement content increased calcium.

https://www.mdpi.com/2071-1050/13/11/6430/pdf

Strength and Durability of Cement-Treated Lateritic Soil

Lateritic soils which have been described as highly weathered tropical or subtropical residual soils were studied with an attempt to establish its suitability or otherwise as sustainable material in building bricks and housing development that will meet the present challenge of sustaining the environment without costing too much and maintaining a high standard of strength, durability and aesthetics. Index properties of the tested lateritic soils revealed them as mostly well graded, comprising both cohesive (silt and clay) and cohesionless (sand and gravel) soil fraction. The geotechnical analyses on the studied lateritic soil revealed a strong compressive strength with a relatively sound dry density which could guarantee a good durability in resulting bricks made from these soil materials. Further test on the strength and durability of the compressed earth bricks (CEBs) made from these lateritic soils revealed a brick with compressive strength ranging between 6.33 and 15.57 MPa which is considered to be of good strength coupled with its sound durability strength established over a period of more than one year under a complete cycle of weather and seasonal conditions. In conclusion, lateritic soils from the study area were found to be suitable as materials for bricks (CEB) with good compressive and durability strength which qualifies them as sustainable and cost-effective materials for low-cost housing development.

Geotechnical characterisation of lateritic soils from south-western Nigeria as materials for cost-effective and energy-efficient building bricks

The effect of two agro-based admixtures—coconut shell ash (CSA) and coconut husk ash (CHA)—on lime-stabilized lateritic soil were assessed and their results were compared with respect to the most potent stabilizer that can be used for the stabilization of lateritic soil as sub-base material in this study. Engineering properties such as California bearing ratio (CBR) and unconfined compressive strength (UCS) were determined for both stabilizers. The peak values of the CBR and UCS for the CSA were obtained when the soil was treated with a combination of 4% CSA + 4% lime content while that of the CHA were observed at a combination of 16% CHA + 4% lime content. However, the CBR and UCS values for the CSA were found to be higher than that of the CHA treated soil. The UCS and CBR for the soil specimens treated separately with CSA and CHA did not meet the criteria necessary to be qualified as sub-base material but they adequately satisfy the requirement as subgrade material.

Comparative Assessment of the Stabilization of Lime-Stabilized Lateritic Soil as Subbase Material Using Coconut Shell Ash and Coconut Husk Ash

The study was conducted to investigate the different effects of cement-sawdust ash and cement on a clayey soil sampled from Mandate Lodge, Landmark University, Omu-Aran, Nigeria The binder mix of cement sawdust ash (CSDA) was mixed in a ratio of 1:1 The CSDA and cement were added to the soil samples at varying percentages of 15, 30, 40, and 70% by weight of the soil Atterberg limits and strength tests (unconfined compressive strength (UCS) and direct shear (DS) test) were performed on the samples to determine the suitability of the stabilized soil as a construction material in highway pavement Atterberg limit test result showed that the addition of 7% cement decreased the liquid limit from 58% to 42% and plasticity index from 18% to 3%, while the addition of 7% CSDA decreased the liquid limit from 58% to 48% and plasticity index from 18% to 4% The Atterberg limit test results also showed that the stabilized clayey soil samples met the requirements of the Nigerian General Specifications of maximum plasticity index (PI) of 30% and liquid limit (LL) of a maximum of 50% when used as a subgrade material in highway construction The strength test result showed that the strength values of the samples increased with binder addition and met with the requirement for use as a subgrade material in highway construction

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Geotechnical properties of clayey soil stabilized with cement-sawdust ash for highway construction

An attempt to stabilize some soils from failed sections of the Sagamu–Papalanto road, southwestern Nigeria with lime was undertaken with a view to improve the geotechnical properties of the soils. The soils were treated with 0 % to 20 % by mass of lime, compacted at the Modified AASHTO level and subjected to consistency limits, unconfined compressive strength (UCS) and California bearing ratio (CBR) tests. Increasing content of lime addition resulted in soils with reducing plasticity with an optimum range of 6 % to 8 % while the UCS and CBR increased. Furthermore addition of between 6 % and 10 % of lime produced soils with desirable strength for use as base course materials. However despite the continuous increase in CBR with increasing lime addition, none of the soils meet the unsoaked CBR requirement for use as base course materials. However the soils qualify for use as subbase materials. Thus, it can be concluded that, the soils responded positively to lime addition; however the degree of response and the eventual effect on its suitability for use varied from soil to soil.

An attempt to improve geotechnical properties of some highway lateritic soils with lime Poskus izboljšave geotehničnih lastnosti nekaterih lateritnih tal za ceste z dodajanjem apna

Jennifer Okosun

Papers

An attempt to improve geotechnical properties of some highway lateritic soils with lime Poskus izboljšave geotehničnih lastnosti nekaterih lateritnih tal za ceste z dodajanjem apna