Cement stabilization treatment of lead and naphthalene contaminated lateritic soils

This article presents an investigation on the influence of Ordinary Portland Cement (OPC) as a binder in the stabilization treatment of lateritic soil contaminated with lead or naphthalene. To evaluate the performance of the binder, the contaminated soils were tested for mechanical strength and environmental performance before and after the stabiliza­tion treatment. Results showed that the strength as inferred from the unconfined compressive strength (UCS) and cohesion values increased with the addition of the binder. Cement stabilization of the lead contaminated samples also prompted a reduction in the release of lead below the admissible limit during the leaching test. Cement stabilization of the naphthalene contaminated samples, on the other hand, could not contain the release of naphthalene below the regulatory level during the leaching test. The batch equilibrium adsorption test (BEAT) showed that cement stabilization increased the adsorption capacity of the soil for the contaminants

Geotechnical Properties of Clayey Soil Stabilized with Cement-Sawdust Ash for Highway Construction

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 cementsawdust ash (CSDA) was mixed in a ratio of 1:1. The CSDA and cement were added to the soil samples at varying percentages of 1.5, 3.0, 4.0, and 7.0% 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

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

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 1.5, 3.0, 4.0, and 7.0% 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

Solid waste characterization and its recycling potential: Akure municipal dumpsite, Southwestern, Nigeria

This study was undertaken to characterize and determine the recycling potential of municipal solid waste brought to a cen�tralized facility in Akure, Nigeria. The facility serves a population of over 350,000 people. For a year, waste brought to the municipal solid waste facility from three sources namely market, residential and curbsides were characterized and quantified monthly. Physical and chemical characteristics of the waste were determined using standard methods. Data obtained were analyzed using statistical analysis. The results showed that an average of 0.17 ton of waste is transported to the dumpsite from the three major sources every day. There were statistically significant differences in all the types of waste except paper brought from the three sources. The wastes transported from the three sources in the city to the dumpsite were mainly com�posed of paper at 17.3%, nylon at 26.6%, organic waste at 25% and sand at 18.9%. These obtained values were compared with waste generated in the same area from studies in the literature. The chemical conditions of the organic waste showed that it could be used for efficient composting. The usage of the recycling plant was not effectively maximized, despite the high (96%) recyclable potentials of the waste

Assessment of the impact of abattoir activities on the physicochemical properties of soils within a residential area of Omu-Aran, Nigeria

Waste effluents from abattoirs have been documented to have harmful effects on the soil media. There is little information about the level of contamination by abattoir effluents on the soil media in Omu-Aran. This study therefore assessed soil samples for possible contamination of physicochemical parameters and heavy metals from different points and some meters away from the mini abattoir in Omu-Aran, Kwara State, Nigeria. Soil samples which are 18 in number were collected from the soil around wells which are owned by individuals and a well designated as Control situated at distances which vary and different elevations to the abattoir. The physicochemical parameters of the soil samples were obtained by applying the standard methods. The analysis of data was achieved using descriptive statistics and ANOVA. The mean values of parameters in the soil samples collected around the studied wells ranged from 31.00±2.00–110.03±8.72 mg/L and 7.21±0.02–7.83±0.02 for electrical conductivity and pH respectively. Chloride, nitrate and phosphate had values of 6.37±0.13–9.13±0.21 mg/L, 3.67±0.07–4.50±0.31 mg/L and 3.86±0.07–5.41±0.30 mg/L respectively. However, average values for heavy metals (Ni, Cr and Pb) though slightly higher than the control site, were above permissible limits. Activities within Omu-Aran Abattoir impacts negatively on the surrounding arable soils; therefore, pollution control procedures which are sustainable should be implemented for abattoirs situated in residential area

Strength and Hydraulic Conductivity Characteristics of Sand-Bentonite Mixtures Designed as a Landfill Liner

Compacted sandy soils with addition of bentonite have been used in a variety of geotechnical structures as engineered barriers, such as in landfill liners and hydraulic containment structures. In this study, Igbokoda sand was mixed with bentonite at varying percentages of 0%, 2%, 4%, 6%, 8% and 10% by weight of sand. Strength tests, which include compaction test, California Bearing Ratio (CBR) test and direct shear test, were performed on various sand-bentonite mixtures using standard methods. Hydraulic conductivity tests were also performed on various sand-bentonite mixtures in order to determine their suitability as landfill liner. Results from the tests showed that 8% of bentonite with sand mixture had a hydraulic conductivity below 1×10-7 cm/s, a cohesion value of 250 kN/m3 and a reasonable strength (CBR) value of 54.07% using the West Africa standard compactive method, hence being the safest of the selected varying percentages for the design of a landfill liner

Environmental Performance of Lime–Rice Husk Ash Stabilized Lateritic Soil Contaminated with Lead or Naphthalene

This study evaluates the environmental performance of a lime–rice husk ash stabilized lateritic soil that had been contaminated with either lead or naphthalene. The Lime and Rice husk ash mixed in a ratio of 1:2 was used as a stabilizing binder and added to the contaminated soil at diverse quantities of 5 and 10% by weight of the contaminated samples. Environmental performance of the soil-contaminant-binder mixes were evaluated from the leaching and batch equilibrium adsorption tests conducted on the samples. Mineralogical analysis was also carried out on the leached samples using the X-ray diffractometer to determine the predominant minerals. The leaching test revealed that the lead concentration in the leachate was reduced below the allowable standard limit of 5 mg/l for lead, even after a duration of disturbed shaking at pH 3 ± 0.5 as the binder addition was increased from 0 to 5 to 10%. The binder addition was not effective to reduce the leachate concentrations of the naphthalene contaminant below the allowable standard limit for naphthalene in soil which is 0.2 µg/l. The batch equilibrium adsorption test showed that lateritic soil had a good adsorption capacity for both contaminants, which increased with an increase in the binder addition

Compacted Sawdust Ash-Lime Stabilised Soil-Based Hydraulic Barriers for Waste Containment

This study examined the impact of sawdust ash–lime (SDAL) stabiliser on the geotechnical characteristics of lateritic soil as an effective hydraulic barrier system for landfill liner application. SDAL mixtures in the ratio 2:1 were added to the lateritic soil at varying percentages between 0 and 10%. The soil–SDAL mixtures were then compacted using four integrative methods: reduced Proctor, standard Proctor, West African Standard and modified Proctor. Index geotechnical tests were carried out on the lateritic soil; hydraulic conductivity and unconfined compressive strength (UCS) tests were carried out on the compacted SDAL-stabilised lateritic soil. Results show that the addition of SDAL decreased the maximum dry density and increased the optimum moisture content. Hydraulic conductivity (k) values decreased with low (i.e. 2%) addition of SDAL, while UCS increased with SDAL addition. Apart from the SDAL addition, the compacting effort and the curing periods also had an effect on the hydraulic conductivity and UCS values of the samples. Compacted SDAL-stabilised lateritic soil (with as little as 2% SDAL) can therefore be applied as a low-cost soil-based hydraulic barrier for waste containment

Strength Characteristics of Lead and Hydrocarbon Contaminated Lateritic Soils Stabilized with Lime-Rice Husk Ash

This study investigates the strength characteristics of the lead and hydrocarbon contaminated lateritic soil stabilized with lime-rice husk ash, a binder additive combined at a ratio of 1:2 Lime: Rice husk ash. The artificially contaminated Akure lateritic soil was stabilized with varied degrees of 5 and 10% of the binder by weight of the contaminated soil samples. Strength characteristics tests which include unconfined compressive strength and direct shear tests were then conducted on the soil-contaminant-binder mixes. The 10% binder addition produced the highest percentage increase in the strength characteristics which were in the range of 31.1%- 47.7% and 41.4%-70.0% for the unconfined compressive strength on lead and naphthalene contaminated samples respectively. The influence of the contaminants and binder additives on the allowable bearing capacity (qa) of the lateritic soil was inferred from the trend observed in the unconfined compressive strength (qu)

Risk assessment and rehabilitation potential of a millennium city dumpsite in Sub-Saharan Africa

Management of the ever-increasing generated solid waste had been a difficulty for state governments in Nigeria. The high costs connected to this waste management which had encumbered the state budget, ignorance or lack of understanding of resourceful waste management and insensitivity to environmental concerns may have led to partial neglect of this sector. This research paper is aimed at evaluating the rehabilitation potential and the risk level of Igbatoro dumpsite, an Ondo state-managed waste dumpsite which predominantly receives the waste of Akure and its environs. In determining rehabilitation/reconstruction potentials and assessing the risk of the dumpsite, an Integrated Risk Based Approach (IRBA) was considered. The Risk Index (RI) was calculated from the addition of the sensitivity index output with the attribute weightage of the twenty-seven (27) parameters studied. A total risk index of 571.58 was obtained for Igbatoro dumpsite indicating moderate hazard evaluation. Questionnaires distributed to dwellers around the dumpsite also showed that 83.6% of those interviewed agreed that the present management of the dumpsite is poor while 81.8% supported rehabilitation of the dumpsite. Hence, reconstruction of the Igbatoro dumpsite to an endurable and controlled landfill is hereby recommended