Cement bentonite (CB) barriers are selfsupporting, low permeability, structures used to retard groundwater flow and as such strength and hydraulic conductivity parameters are often stipulated when developing the mixtures. This paper reports an investigation into the deformation and compression behaviour of a CB containing ground granulated blastfurnace slag using the unconfined compressive strength apparatus, triaxial (undrained, unconsolidated) and oedometer. Samples were also exposed to drying and rewetting to investigate possible response to changes in environmental conditions. Cracking was observed prior to peak stress suggesting that the hydraulic conductivity of a barrier may be adversely affected before the shear strength is reached in undrained conditions. The compression response of CB indicates the presence of a threshold stress; once exceeded the magnitude of settlements are significantly greater than those encountered below this threshold. If a barrier experiences localised changes in loading conditions then there is the potential for damage from induced differential settlements; thus it is recommended that the threshold stress should also be considered at the design stage in addition to strength and hydraulic conductivity requirements. The response of the material exposed to drying-rewetting was unexpected and requires further investigation to determine how a barrier will respond to changing environmental conditions.
Large-scale and small-scale spilt oil is as old as exploration activities in the Niger Delta region of Nigeria. There is a need to provide the exposure, geochemical and spatial characteristics in the Niger Delta Region of Nigeria because of the effects of the spilt oil on the communities and the environment. Some of the spilt oil-disaster impacts for exposed communities include psychological effects and socio-demographic characteristics. In this study, the characteristics, sources, spatial and socio-demographic risk predictions of the spilt oil discovered by Kolo Creek coastal residents are examined. A random sample of 900 residents of Kolo Creek coastal communities included exposure characteristics linked to health, the social and economic lifestyle of the communities. The demographic characteristics included age, gender, literacy, and occupation as covariates in the analyses. Respondents provided varied information on the amount of health, the social, and economic impacts. The highest and lowest direct exposure impact accounts 94.65±2.0% and 5.95±1.52% for smoggy weather and obstruction to watercourses respectively. The geochemical distribution pattern was examined using standard laboratory procedures. This investigation included the determination of the physical and chemical characteristics of water samples at the oil spill sites. Also, the biochemical oxygen demand (BOD), chemical oxygen demand (COD), total hydrocarbon content (THC), and total petroleum hydrocarbon (TPH) of both water and sediment samples were carried out. A strong correlation exists between these parameters (i.e. at p < 0.01) and indicate communalities greater than 0.5. The pollution distribution maps support the spatial distribution pattern and correlate significantly (p < 0.01) with the exposure distribution, and the geochemical distribution patterns.
No abstract
Collapsible soils have caused infrastructural damages resulting in several economic losses and loss of lives in certain cases. The prerequisite for collapse occurring is an open metastable structure; capable of developing in any soil type given the right placement or aging conditions. Natural and anthropogenic (engineered and non-engineered) collapsible soils exist in many regions of the world. In their unsaturated state, these soils exhibit high enough shear strength and stiffness (provided by inter-particle bonds of either suction, clay, calcium carbonate, or other salts) but upon wetting and/or loading they undergo repacking due to bond softening/weakening. This collapse of the soil structure leads to a rapid volume decrease and consequently associated issues such as rapid differential settlement, ground fissuring and landslides occur causing damages to civil structures, and loss of lives. Despite these threats and the large body of research available in this subject, there is still poor understanding of the process of softening/weakening and the collapse mechanism of certain bond in some collapse elements. The aim of this paper is to provide a state-of-the-art comprehensive review of the different types of collapsible soils, field, and laboratory methods of predicting and measuring their potential to collapse. This understanding is crucial for geotechnical characterisation of soils in order to design safe and economic infrastructures with their long-term serviceability also in focus.
This paper investigated the geochemical, bacteriological, and geotechnical characteristics of a smectite clay sourced in the Niger Delta Region of Nigeria and its application as a barrier system for the containment of pollutants in aqueous systems. The smectite clay was tested for various geochemical, bacteriological, and geotechnical properties. The findings revealed that the clay type had the potential to act as a barrier system for toxic heavy metals and bacteria in aqueous systems. The hydraulic conductivity of the smectite clay under effective stress of 80 kN/m 2 was 1.6 x 10-10 m/s to natural aqueous contaminants contained in the Gbarain watershed of the Niger Delta region of Nigeria. The Gbarain watershed contained Lead (>0.01 mg/L), Mercury (>0.006 mg/L), Manganese (>0.4 mg/L) and Escherichia coli (>0 cfu/100ml). Uptake of the inorganic contaminants and inhibition of bacteria by the smectite clay was significant and increased with an increase in pH. In conclusion, smectite clay would provide an excellent geochemical, bacteriological, and geotechnical barrier system for toxic heavy metals and bacteria migration into a watercourse.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.