Settlement of Multi-Story Buildings on Sand Fills

The behaviour of two residential buildings with shallow foundations supported on sand fills with underlying soft alluvial deposits are discussed. Regular settlement measurements were taken for four and seven years on the foundations of the nine-storey and five-storey buildings respectively. Measured settlements have been compared with predictions based on the theory of one-dimensional consolidation. The factors that might have been responsible for the lower predicted settlement values are highlighted

Improvement of the Index and Compaction Characteristics of Black Cotton Soil with Palm Kernel Shell Ash

The expansive soil obtained from Baure in Yamaltu Deba Local Government Area was rich in clay mineral (montmorillonite), unstable and difficult to use for construction purposes. The soil treated with up to 12% palm kernel shell ash (PKSA an agro – waste) by weight of dry soil to improve index properties and compaction characteristics of the soil using PKSA.  Index tests were carried out to classify the natural soil, while the moisture-density relationships were determined by compaction tests on the natural and treated soils using three energy levels viz, British Standard light (BSL), West African Standard (WAS) and British Standard heavy (BSH). BCS used in the study was classified as A-7-5 (20) using the American Association of State Highway and Transportation Officials (AASHTO) and CH group in the Unified Soil Classification System (USCS). Tests results show that specific gravity of the soil increased from 2.29 for the natural to 2.34 at 12% treatment. Liquid limit decreased from 76.2% for natural to 73.4% at 10% PKSA content. Plastic limit increased from 40% for the natural soil to 47.1% at 12% PKSA content treatment. Maximum dry density (MDD) values decreased from 1.44Mg/m3, 1.5Mg/m3 and 1.65Mg/m3 for the natural soil to 1.38Mg/m3 at 10%, 1.45Mg/m3 at 10% and 1.56Mg/m3 at 6%  PKSA content for BSL, WAS and BSH compaction energy levels respectively. On the other hand, optimum moisture content (OMC) value decreased from 28.5% and 22.4% for the natural soil to 22.4% and 21.0% at 12% PKSA content for BSL and WAS energies respectively while the value for BSH energy increased from 18.2% to 19.0% at 8% PKSA content. Results show that PKSA is suitable for the improvement of the index properties and compaction characteristics of BCS; and its beneficial use will reduce the attendant disposal problem on the   environment

EVALUATION OF SHEAR STRENGTH OF COMPACTED IRON ORE TAILINGS TREATED LATERITIC SOIL

This paper presents the results of a laboratory study on the evaluation of the shear strength of compacted iron ore tailings (IOT) treated lateritic soil. Lateritic soil used was treated with 0 up to 16% IOT by weight of dry soil. Test performed include index test, compaction (using British Standard Light, BSL and West Africa Standard, WAS energies) and shear strength test. One-way analysis of variance was carried out using Microsoft Excel to determine the level of significance of IOT on the treated soil. The results of the triaxial test show that there is an improvement in the shear strength of soil with the improvement of its shear strength parameters (cohesion and angle of internal friction). Cohesion values decreased from 0 up to 8% IOT content and then increased while the angle of internal friction risen from 0 up to 8% IOT content and then decreased. Also, from the triaxial test carried out with varying cell pressures from 100 to 300 kN/m2, an increase in shear strength parameters and shear strength were recorded. The shear strength increased in value by 49.79% and 18.15% for BSL and WAS compaction at 8% IOT content, respectively. Statistical analysis carried out on the results using analysis of variance (ANOVA) shows that IOT has a significant effect on the lateritic soil. An optimal blend of 8% IOT improved the shear strength of the soil and can be used for geotechnical engineering applications such as roads and embankments

Influence of bentonite on clayey soil as a landfill baseliner materials

With the geometric population growth in developing nations comes increase in waste generation, these wastes ranging from industrial to agricultural to municipal solid waste calls for measure for its effective management and disposal so as to preserve the ecosystem. An effective measure of containing this large waste generated, is through the use of landfills which are designed and built to protect infiltration of leachates from decomposed waste to the groundwater. It is with this in mind, that this study seeks to assess the effect of bentonite (0 to 15%) on clayey soil as a base liner for landfills. In achieving this aim, two clayey samples gotten from a borrow site at a depth of 1.5 and 2.0m for samples A and B respectively were modified with bentonite. Particle size analysis, moisture- density relationship and permeability tests were performed on the test and the bentonite-modified samples in accordance with relevant standards. Result shows an increasing plasticity index, and liquid limit of both samples with increasing bentonite content. Permeability and dry densities of the samples decreases on bentonite modification. The application of bentonite modified the soil as it improves their plasticity and hydraulic properties. Bentonite modification made the claye

TECNOLOGÍAS PARA VÍAS TERCIARIAS: PERSPECTIVAS Y EXPERIENCIAS DESDE LA ACADEMIA

Las selección de las tecnologías a emplear para la construcción y mantenimiento de vías terciarias es una actividad que debe tener en cuenta las condiciones particulares de cada proyecto. Esto incluye realizar una caracterización detallada de los suelos existentes en la zona -sobre los cuales se construirán las vías- y de las condiciones climáticas del lugar. Así mismo, se deben identificar las fuentes de materiales disponibles para la construcción de las estructuras de pavimento y se debe evaluar la posibilidad de modificar algunos materiales locales que no cumplen con las especificaciones técnicas vigentes, con el objetivo de transformarlos en materiales competentes. El objetivo inicial de este artículo es destacar algunos aspectos relacionados con la selección y empleo de tecnologías para vías terciarias que, desde el punto de vista de la academia, son prioritarios para garantizar el éxito de estas iniciativas. Adicionalmente, con el objetivo de resaltar el rol de la investigación en el desarrollo de este tipo de proyectos viales, el documento también describe dos trabajos realizados recientemente por la Universidad de los Andes en relación con el empleo de materiales no convencionales para la construcción de vías terciarias.

Foreign Direct Investment, Aggregate Demand Conditions and Exchange Rate Nexus: A Panel Data Analysis of BRICS Economies

In this study, we attempt to provide underlying theoretical and empirical explanations for exchange rate appreciation due to foreign capital influx and aggregate demand conditions in the BRICS economies. The empirical analysis is based on a panel dataset of BRICS countries over the time period 1992–2013 to substantiate our theoretical findings. For panel co-integration, Pedroni and Johansen-Fisher panel co-integration tests are conducted to compare co-integration among panel countries. We also analyze the results from Dumitrescu-Hurlin panel causality test among variables and use Granger Causality to test for the causal patterns in each of the individual countries. Our findings showed that the exchange rate volatility is directly affected by the flows of FDI, GDP per capita, Capital formulation and House hold consumption. The results have profound implications in terms of exchange rate stability in the BRICS countries and associated risks

The bii4africa dataset of faunal and floral population intactness estimates across Africa’s major land uses

Sub-Saharan Africa is under-represented in global biodiversity datasets, particularly regarding the impact of land use on species’ population abundances. Drawing on recent advances in expert elicitation to ensure data consistency, 200 experts were convened using a modified-Delphi process to estimate ‘intactness scores’: the remaining proportion of an ‘intact’ reference population of a species group in a particular land use, on a scale from 0 (no remaining individuals) to 1 (same abundance as the reference) and, in rare cases, to 2 (populations that thrive in human-modified landscapes). The resulting bii4africa dataset contains intactness scores representing terrestrial vertebrates (tetrapods: ±5,400 amphibians, reptiles, birds, mammals) and vascular plants (±45,000 forbs, graminoids, trees, shrubs) in sub-Saharan Africa across the region’s major land uses (urban, cropland, rangeland, plantation, protected, etc.) and intensities (e.g., large-scale vs smallholder cropland). This dataset was co-produced as part of the Biodiversity Intactness Index for Africa Project. Additional uses include assessing ecosystem condition; rectifying geographic/ taxonomic biases in global biodiversity indicators and maps; and informing the Red List of Ecosystems

The bii4africa dataset of faunal and floral population intactness estimates across Africa’s major land uses

Sub-Saharan Africa is under-represented in global biodiversity datasets, particularly regarding the impact of land use on species’ population abundances. Drawing on recent advances in expert elicitation to ensure data consistency, 200 experts were convened using a modified-Delphi process to estimate ‘intactness scores’: the remaining proportion of an ‘intact’ reference population of a species group in a particular land use, on a scale from 0 (no remaining individuals) to 1 (same abundance as the reference) and, in rare cases, to 2 (populations that thrive in human-modified landscapes). The resulting bii4africa dataset contains intactness scores representing terrestrial vertebrates (tetrapods: ±5,400 amphibians, reptiles, birds, mammals) and vascular plants (±45,000 forbs, graminoids, trees, shrubs) in sub-Saharan Africa across the region’s major land uses (urban, cropland, rangeland, plantation, protected, etc.) and intensities (e.g., large-scale vs smallholder cropland). This dataset was co-produced as part of the Biodiversity Intactness Index for Africa Project. Additional uses include assessing ecosystem condition; rectifying geographic/taxonomic biases in global biodiversity indicators and maps; and informing the Red List of Ecosystems