Characterization of Geotechnical Properties of Lateritic Soil-Bentonite Mixtures Relevant to Their Use as Barriar in Engineered Waste Landfills

The purpose of this study was to characterize lateritic soil bentonite mixtures intended for use as low-permeability barrier in municipal waste disposal land ll. Characterization of the soil mixtures included measurement of Atterberg limits, compaction properties, hydraulic conductivity, shear strength, and desiccation shrinkage potential. Accordingly, laboratory tests involving soil mixtures with 0, 2.5, 5, 7.5 and 10% bentonite contents, prepared at varying compaction states (2% dry of optimum, optimum and 2% wet of optimum) and compacted using West African stan- dard (WAS) compactive e ort were carried out. Results show that mixtures with bentonite are adjudged to be suitable materials for liners because they met the statutory hydraulic conductivity requirement (i.e., k ≤ 1.0 x 10-9 m/s). Acceptable volumetric shrinkage strain of ≤ 4% (a maximum allowable volumetric shrinkage found in literature and adopted by most regulatory agencies for barrier material) was maintained by most soil mixtures. Although, slight reduction in shear strength was established, uncon ned compressive strength (UCS) values for all soil mixtures met or exceeded the general speci cation i.e., UCS ≥ 200 kN/m2 required for performance in waste repositories.Keywords: barrier, bentonite, hydraulic structures, lateritic soil, waste land l

Compressibility Characteristics of Compacted Black Cotton Soil Treated with Rice Husk Ash

One dimensional consolidation studies on compacted black cotton soil treated with up to 16% rice husk ash (RHA) at the British Standard light compactive effort was carried out to access the compressibility characteristics. The consolidation characteristics of black cotton soil containing 0, 4, 8, 12, and 16% RHA were observed at different moulding water contents (2% dry of optimum, optimum moisture content and 2% wet of optimum) simulating different field placement conditions. Variations of the soil’s index properties with ash treatment were also observed. The Atterberg limits showed improved index properties; plastic limit of the soil was found to increase while the liquid limit and plasticity index decreased with increased RHA treatment. The optimum moisture content (OMC) was observed to increase while Maximum Dry Density (MDD) decreased with increased RHA treatment. The swelling pressure decreased with increased RHA content. The consolidation parameters also showed appreciable changes; with the gross yielding stress irrespective of the particle state increasing with increased RHA treatment. The compression index decreased with increased RHA content but increased with increasing moulding water content. The coefficient of volume compressibility, coefficient of consolidation generally decreased with increased loading pressure and RHA treatment for up to 8%.  The coefficient of permeability decreased with increased RHA content for up to 8%. These results show an overall improvement in the consolidation properties for up to 8% treatment; suggesting the suitability of the material in fills for embankment and low lying marginal land for foundation works. This also helps in ameliorating the environmental problems associated with the disposal of waste rice husk ash

Effect of Fines Content on the Engineering Properties of Reconstituted Lateritic Soils in Waste Containment Application

A lateritic soil reddish brown in colour was reconstituted with inclusion of nes content in 0, 20, 40, 60, 80 and 90% to form six (6) dierent soil mixes (S1, S2, S3, S4, S5 and S6, respectively). These soils were analysed to determine the eect of nes content on their engineering properties. Tests were carried out to determine index properties, compaction characteristics, strength properties (unconned compressive strength (UCS) and undrained shear strength parameters) and hydraulic properties of the reconstituted soils. Specimens used for the determination of UCS, undrained shear strength parameters and hydraulic properties were prepared at the optimum moisture content (OMC) and compacted using the British Standard light, BSL (standard Proctor) energy. Reconstitution of the natural soil (0% nes content) yielded soil samples having fines content between 61 and 93%, and grading modulus that decreased with higher nes content. The specic gravity of the reconstituted soils decreased, while the Atterberg limits as well as derived plasticity parameters increased with higher nes content. The maximum dry density (MDD) and OMC decreased and increased, respectively, with higher nes content. The UCS and angle of shearing resistance generally decreased while cohesion increased with increase in nes content. The hydraulic properties improved with higher nes content. Test results indicate that the reconstituted lateritic soil samples meet the relevant requirements for materials to be used as hydraulic barrier in waste containment structures.Keywords: compaction, derived plasticity parameters, hydraulic barrier, hydraulic conductivity, reconstituted lateritic soi

Effect of Treatment Compositions on the Plasticity of Tropical Red Soil Treated with Bacillus Coagulans

The study evaluated the effect of four treatment compositions on the plasticity of tropical red soil (Lateritic soil) admixed with Bacillus coagulans (B. coagulans). Samples for Atterberg limits test were prepared using four treatment compositional variables. They include 25% B. coagulans suspension and 75% cementation reagent, (25%B /75%C); 50% B. coagulans suspension and 50% cementation reagent (50% B /50%C); 75% B. coagulans suspension and 25% cementation reagent, (75%B /25% C) with the above three being in equivalent volumes of the corresponding liquid limit(LL) and 50% of the optimum moisture content (OMC) of compaction, to be both  B. coagulans suspension and cementation reagent (i.e. 50% OMC B /50%OMC  C) of the natural soil. Results showed that the LL for; 25%B /75% C, 50% B /50% C and 75% B /25%C generally increased from 0 up to peak values at 1.8 x 109 cells/ml and then declined at 2.4 x 109 cells/ml. In the case of samples treated with 50% OMC B/50% OMC C, the LL initially decreased from 0 up to 6.0 x 108 cells/ml and thereafter increased significantly. Plastic limit (PL), Plasticity index (PI) and Linear shrinkage (LS), recorded improvement. Regression analysis for the best treatment composition (i.e 75%B /25%C) has regression coefficient of 91.8%. Based on the four treatment compositions considered, 75%B/25%C enhanced the soil workability significantly and is suggested for geotechnical engineering applications such as road pavements that are lightly trafficked

Microanalysis and Compactive Efforts Study of Black Cotton Soil Treated With Cement Kiln Dust

An expansive clay, also known as Black cotton soil (BCS) was treated with up to 10 % cement kiln dust (CKD) using three different compactive efforts; British Standard light (BSL), West African Standard (WAS) and British Standard heavy (BSH) energies. Laboratory tests were performed on the natural soil and CKD treated soil samples in accordance with BS 1377 (1990) and BS 1924 (1990) respectively with the aim of improving the deficient soil to meet engineering requirements. Preliminary evaluations on the natural black cotton soil showed that it fell under A-7-6 (16) using AASHTO classification and CL according to Unified Soil Classification System (USCS). Results of laboratory tests carried out on soil specimens show that the properties of the soil generally improved with CKD treatment. Peak unconfined compressive strength (UCS) values of 357.07, 382.49 and 528.82 kN/m2 and California bearing ratio (CBR) of 7, 10 and 19 % as well as resistance to loss in strength of 44, 55 and 55 % were recorded at 10 % CKD treatment, respectively, for BSL, WAS and BSH compactive energies. Reduction in the particle sizes with curing period was observed when samples were viewed through the scanning electron microscope (SEM). The study showed that CKD can be beneficially used to improve the subgrade of lightly trafficked roads and as admixture in lime stabilization during construction of flexible pavements over expansive soil.Keywords: California bearing ratio; Cement kiln dust, Durability; Expansive soil; Microanalysis, Unconfined compressive strength; Scanning electron microscope

The use of microscopy and rapid diagnostic test in diagnosing the prevalence of malaria among women attending antenatal clinic in Dutsin Ma, Katsina State, Nigeria

Malaria during pregnancy continues to be an overwhelming health problem in endemic countries especially in sub-Saharan Africa with clinical consequences. This study was to determine the occurrence of malaria parasite and to compare the use of Microscopy and Rapid Diagnostic Tests (RDTs) in diagnosis of malaria parasite in pregnant women in Dutsin-Ma LGA of Katsina State. Two hundred (200) blood samples were collected from pregnant women and tested for malaria parasites using thin smears and RDTs. Interviews were conducted and structured questionnaires administered to obtain information on the clinical and social aspects of malaria; of which the response was 85% positive to the symptoms and causes of malaria, 60.5% were found to be infected with malaria and 39.5% where negative. Out of 60.5% that tested positive for malaria, only 20% tested positive using RDTs. Plasmodium falciparum was the only specie isolated.The result showed that malaria infection was prevalent during pregnancy and young women (age-groups 15-19 years) recorded the highest prevalence (78.4%). The pregnant women in their second gestational period recorded the highest occurrence of 77.9% (p>0.05). Among the gravid-status, Primigravidae had the highest prevalence rate of 65.7% (p<0.05); while among the educational group, those with tertiary education had the highest percentage (72.7%). A high percentage of the respondents attributed malaria infection to mosquito bites. The result from this work shows that RDTs might not be an accurate diagnosis in demonstrating the presence of parasitaemia.Keywords: Diagnosis; rapid diagnostic test; Dutsin-Ma; Katsina; microscopy; malaria; prevalence; pregnancy; Nigeri

Effects of drug treatments on Worm burden and enzyme levels in Schistosoma haematobium infected laboratory Animals

This study was carried out to evaluate the effect of drug treatments and enzymes level on the worm burden in an experimental Schistosoma haematobium infected guinea pig. Eggs of S. haematobium were collected from the urine of infected persons and hatched into miracidia. Fresh water Snail species Bulinus truncatus were exposed to miracidia and allowed for five weeks to establish infection and develop to cercaria. Guinea pigs were exposed to S. haematobium cercaraie by subcutaneous injection. The infected guinea pigs were divided into four groups, designated as 7, 28, 90 days post infection and controls. The guinea pigs were treated singly and in combination with different doses of Praziquantel (PZQ), Artemether (ART) and Artequine (ARQ). The efficacy of the different drugs on worm burden were assessed. Blood samples were collected from the guinea pigs before and after treatment for determination of Alkaline Phosphatase (ALP), Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST). Result showed that treatment with higher doses of PZQ/ART (100/200mg/kg) and PZQ/ARQ (100/200mg/kg) resulted in total worm reduction rate of 58 and a percentage efficacy of 98.3%. ARQ (300 mg/kg) had the highest percentage efficacy of 89.8% amongst the single drugs used with respect to higher doses. There were observed alteration in the levels of the enzymes after S. haematobium infection. The serum level of ALP, AST and ALT after infection generally decreased. There were various activities in the level of ALPAST and ALT after treatment with different drug regimen at different stages of S. haematobium infection. ARQ alone and in combination with PZQ had anti schistosomal effect and could be promising in controlling schistosomiasis. Keywords:  S. haematobium, Guinea Pigs, Liver functioning enzymes, Worm burde

The geotechnical properties of black cotton soil treated with crushed glass cullet

This study is an investigation into the effect of crushed glass (glass cullet), a waste material, on some of the geotechnical properties of Black Cotton Soils (BCS) of North-Eastern Nigeria. The investigation includes evaluation of properties such as consistency limits, index properties, shear strength parameters, Unconfined Compressive Strength, California Bearing Ratio, permeability and potential volume change of the soil with up to 20% glass cullet content. The results obtained showed that the liquid limit and plastic limit decreased with an increase in glass cullet content, while the plasticity index increase with an increase in glass cullet content. The specific gravity increased with an increase in glass cullet content. It was also discovered that increase in glass cullet content decreased the Optimum Moisture Content (OMC) and increased the Maximum Dry Density (MDD) in Compaction. The Optimum Moisture Content (OMC) from the Compaction test was used to prepare the samples used in Direct Shear test (Shear Strength Parameter test), Unconfined Compressive Strength (UCS) test, Permeability test, California Bearing Ratio (CBR) and Potential Volume Change tests. From these tests, cohesion was found to be decreasing with increase in glass cullet content and the angle of internal friction increases as the glass cullet content increased. The Unconfined Compressive Strength test (UCS), permeability test and California Bearing Ratio test (CBR) increases as glass cullet content increased. Also the swelling pressure reduced with increased glass cullet content. These results reveal the suitability of the material in improving the geotechnical properties of the soil and a potential solution to the environmental nuisance created by glass cullet.Keywords: Black cotton soil, Glass cullet, Geotechnical properties

Influence of Delay after Mixing on Compaction Characteristics of Cement- Locust Bean Waste Ash Modified Lateritic Soil

A lateritic soil modified with up to 4% of ordinary Portland cement (OPC) and up to 8% of locust bean waste ash (LBWA) by dry  weight of soil was evaluated for use in road construction. Lateritic soil – OPC - LBWA mixtures were delayed for up to 3 hours aftermixing before compaction at British Standard light (BSL) energy, thus simulating the likely delay in the placement of the mixtures that might occur in the field. Results obtained show that maximum dry density (MDD) values of the natural soil increased from 1.62 to 1.79Mg/m3 at 3 hours delay after mixing when treated with 4% OPC/6% LBWA, while the optimum moisture content (OMC) values decreased from 16.2 to a minimum of 11.33% after 3 hours when the soil was treated with 2% OPC/4% LBWA blend. Statistical analysis was carried out on results obtained using analysis of variance (ANOVA) with the Microsoft Excel Analysis Tool Pak Software Package to determine the levels of significance of effect of cement/ and LBWA on the properties of the soil. The effects of cement and LBWA from the results obtained were not statistically significant on the compaction characteristics. Based on the results obtained from the study, it is recommended that an optimal mix of 2% OPC/6% LBWA be used for the modification of lateritic soil and should not be placed more than 2 hours after mixing for the construction of sub-base and base of lightly trafficked roads. ©University of Ibadan Keywords: Compaction, Delay, Lateritic soils, Locust bean waste as

Effect of selected admixtures on the geotechnical properties of black cotton soil

The effect locust bean waste ash (LBWA) and cement kiln dust (CKD) on black cotton soil (BCS) was studied. BCS was modified with 0, 2, 4, 6, 8 and 10 % LBWA and 0, 1, 2, 3 and 4 %CKD in relation to the soil dry weight. Test carried out include cation exchange capacity (CEC), Atterberg limits, compaction and shear strength test. Results show that a combination of LBWA and CKD have negative effect on the geotechnical properties of soil with exception in few cases. The CEC increased with increase in both the LBWA and CKD contents with deviations in few cases. Values of 21.9, 24, 34.1, 33.5, 32.1 and 33.8 Cmol/Kg were recorded at 0, 2, 4, 6, 8 and 10% LBWA content. Similar trend was observed for 1, 2, 3 and 4% CKD. Liquid  limit generally increased with increase in LBWA content while plastic limit generally decreased. In the case of plasticity index, values increased with increase in LBWA content. Peak values were recorded at 6%LBWA content. Maximum dry density (MDD) decreased with increase in LBWA content.  MDD values of  1.68, 1.67, 1.66, 1.65, 1.63 and 1.61 were recorded at 0, 2, 4, 6, 8 and 10% LBWA content. Similar trend was observed for 1, 2, 3 and 4% CKD. Optimum moisture content (OMC) increased with increase in LBWA content. Cohesion of soil decreased with increase in LBWA content. Values of 140, 110, 95, 60, 120 and 180 kN/m2 was recorded at 0, 2, 4, 6, 8 and 10% LBWA content, while angle of internal friction improved from its natural value up to 10% LBWA content. Statistical studies by means of two–way analysis of variance (ANOVA) reveal that LBWA and CKD have significant effect on the soil properties. Although the modified soil did not effectively improve the consistency and shear strength parameters of BCS, an optimal blend of 2% CKD/10% LBWA blend slightly improved the soil properties. The optimally modified soil could be utilised for lightly trafficked roads construction as sub-base materials