Isaac I. Akinwumi

Appraisal of Municipal Solid Waste Management, Its Effect and Resource Potential in A Semi-Urban City: a Case Study

Managing municipal solid wastes (MSW) is progressively becoming a major challenge in many cities of developing nations because of rapid urbanization and rise in population. This can be described by ineffective collection methods, inadequate coverage of the collection, processing system and inappropriate disposal. This paper presents the current state of solid waste management in a semi-urban city, its associated challenges and prospects that are within. A field work that involves the characterization and types of the waste generated, and frequency of collection was carried out within the study area. Four locations where the major waste bins are located within the city were considered. A representative sample of 280 kg was used for the waste characterization, and the results show that about 64% of the wastes are recyclable with lots of organic waste that can be used as compost. The only dump site in the city was visited in order to obtain useful information concerning the present state of solid waste management. The study revealed that there is presently no investment made to the existing development plan to introduce a modern waste management system. The study suggests new approach that could be used by institutions and government agencies for MSW management to realize a sustainable and efficient sanitation, and possible resources generation potentials that could be harnessed from the waste stream.

Effects of Steel Slag Addition on the Plasticity, Strength and Permeability of Lateritic Soil

An investigation into the effect of adding pulverized steel slag (an industrial waste product) on some geotechnical properties of a lateritic soil. The soil is A-7-6(5) according to AASHTO classification systems. 5%, 8% and 10% steel slag content (SSC) each by dry weight of soil, was used to stabilize the soil while evaluating the specific gravity, consistency limits, compaction, permeability, uncured and cured strength of the soil. The results obtained show that the increase in SSC decreased the OMC up to 8% SSC but increased the maximum dry unit weight. The increase in SSC reduced the soil plasticity and swell potential and it increased the permeability, cured and uncured strength of the soil. 8% SSC was observed to be the optimum content, based on results of uncured strength of the soil.

Experimental insights of using waste marble fines to modify the geotechnical properties of a lateritic soil

Marble spoil waste is an environmental nuisance. The effects of adding waste marble fines (WMF) on the plasticity, strength and permeability of a lateritic clay have been investigated for its potential use as a soil modifier or stabilizer of road pavement layer materials or earth-building materials. The chemical compositions of the WMF and soil were determined using X-ray fluorescence and atomic absorption spectrometry, respectively. The specific gravity, Atterberg limits, compaction, strength and permeability characteristics of the soil were determined for varying proportions of the soil-WMF blends. The properties of the natural soil–classified as clay of low plasticity (CL) and A-7-6(7), according to unified soil classification and AASHTO classification systems, respectively–were improved after the addition of 10% WMF such that it behaves like a silt of low plasticity. Therefore, WMF is recommended as a low-cost soil modifier or stabilizer for lateritic soil and well-suited for road construction applications

Forensic Investigation of Fire-affected Reinforced Concrete Buildings

This study focused on forensic investigation of fire-affected reinforced concrete buildings. Post-fire investigation was conducted on structural elements in three selected fire-affected concrete buildings, in order to ascertain their in situ residual strengths and also to provide data for use in future assessment of fire-affected buildings. The selected sites for investigation include a five-storey building at Alagbaka and a bungalow at Adegbola in Akure, and a ten-storey building in Benin, Nigeria. Rebound hammer and ultrasonic pulse velocity are two non-destructive tests apparatus used for this investigation. Average values of pulse velocity were fitted into an established model in order to estimate the probable temperature, which the buildings were subjected to. Tests were conducted on beams, columns and slabs in both the affected and the unaffected parts of the buildings. From the results, visual examination of the fire-affected buildings revealed changes in the colour of the concrete, delamination of plaster of slab and exposure of reinforcement for severe cases at various locations on the concrete members. In addition, there was notable reduction in the in situ strengths of the fire-affected structural members when compared with the unaffected members. It was deduced that concrete members subjected to temperatures above 600 0 C lost about 70 % of its strength.

Diameter Inconsistency, Strength and Corrosion Characteristics of Locally-Produced and Imported Steel Reinforcing Bars in Ilorin, Nigeria

There has been increasing incidents of collapse of reinforced concrete buildings in Nigeria. Many research works, suspecting the quality of concrete produced in Nigeria, have focused on concrete with few attention on steel, perhaps because its production is usually in a more controlled environment. Over the years, many clients of building construction projects or their representatives have shown preference for imported steel bars over the locally-produced steel bars. This research work sets out to investigate the quality of steel reinforcement produced locally and compare them with imported steel bars. The diameter of the two classes of bars available in the open market at Ilorin, Nigeria were measured and their deviations from their manufacturer’s designated diameter were determined. Also, their response to the application of load and deterioration in different environments, simulated by their immersion in water, hydrochloric acid (HCL) and sodium hydroxide (NaOH), were studied. Locally-produced bars deviated more from their designated diameter than the imported bars. The imported steel bars have higher strength and experienced lower strain compared to the locally produced steel. They also showed better corrosion resistance, when immersed in distilled water and HCL, than the locally-produced steel bars. The preference for imported steel by clients of building projects is justified.There is a need for regulatory bodies, such as the Standards Organization of Nigeria (SON), to strictly monitor and penalize local steel manufacturers that engage in corrupt practices leading to significant dimensional and strength deviations from specification. This has the potential of minimizing the incidence of building collapse in Nigeria.

Study of Reed-bed of an Urban Wastewater in a Nigerian Community

The need for treatment of municipal wastewater prior to its disposal is important. One method used for treating wastewater is that of a constructed wetland system (CW). The use of a CW has attracted interest in developing nations due to its operational efficiency and cost effectiveness. This paper examines an existing CW in order to determine its effectiveness in the removal of pollutants from a sewer that feeds into a major river system in Nigeria. The CW, which employs hydrophytes to degrade the wastewater from a facility of nearly 10,000 people, is comprised of six cement-block tanks. Samples were collected from the entry and exit points of the CW’s cells and analysed for dissolved oxygen, conductivity, pH and temperature. The pH remained constant (6.8 - 6.9) at ambient temperature of 270C. Conductivity ranged from 700 to 840 ppm. The dissolved oxygen (DO) ranged from 0.9mg/l at the entrance to 0.1 mg/l at the final exit point. Analysis of the data suggests that the CW is not efficient, and steps -- like aeration and an increase in the resident times of the wastewater in each cell of the CW -- need to be taken to improve its performance.

Comparative study of corncob ash-based lateritic interlocking and sandcrete hollow blocks

The high cost of conventional walling materials, increase in emission of CO2 due to cement production and improper disposal of corncob lead to persistent bottlenecks in low-cost and sustainable housing delivery, environmental pollution, and agricultural wastage respectively. This study investigates the use of corncob ash (CCA) as cement additive in producing lateritic interlocking blocks (LIB) and compares its physical characteristics and production cost with Sandcrete hollow block (SHB). Portland limestone cement (PLC) was replaced by CCA in varying percentages 5, 10 and 15%. The density, compressive strength and water absorption of the blocks were determined and compared with the Nigerian standard requirements and specifications. The experimental results showed optimal strength at 3% PLC and 10% CCA with a compressive strength of 4.13MPa, water absorption of 6.60% and density of 1869.47Kgm-3 at 28 days curing for LIB. For 450mm × 225mm × 225mm SHB, compressive strength, water absorption and density at 28 days curing were 3.86MPa, 4.69%, and 1849.95Kgm-3 respectively. All the blocks produced satisfied the recommendations of both the Nigerian Building and Road Research Institute and the Nigerian Industrial Standards. The cost per square meter of SHB and LIB was 4.62 USD and 2.35 USD respectively. The experimental results indicated that LIBs have better strength and are cheaper than SHBs. Recycling of CCA as a supplement material seems to be a feasible solution not only to the problem of adopting indigenous waste material in the production of LIB but also to the environmental problem.

Beneficiated pozzolans as cement replacement in bamboo-reinforced concrete: the intrinsic characteristics

The use of concrete containing supplementary cementitious materials has gained popularity as an eco-efficient and sustainable alternative to a number of concrete applications. In this study, beneficiated pozzolans, ground granulated blast furnace slag (GGBS) and metakaolin (MK), were used as partial replacement of ordinary Portland cement in bamboo-reinforced concrete. In the mixtures, river sand and granite were used as fine and coarse aggregates, respectively. The compressive strength of concrete cubes, split-tensile strength of concrete cylinders, and flexural strength of reinforced concrete beams were determined after stipulated curing regimes. The morphology and mineralogy of bamboo and selected concrete mixtures were obtained using scanning electron microscope and X-ray diffraction, respectively. The concrete samples having blended cement were found to have better compressive and split-tensile strength than those made with conventional binder. Also, the mechanical characteristics of the samples improved up to 40% GGBS substitution. However, steel-reinforced concrete developed better flexural strength than the bamboo-reinforced concrete (BRC). The study recommends pretreatment of bamboo to ensure its adequate bonding with the cement paste, so as to achieve optimum performance of BRC.

Strength and microstructure of eco-concrete produced using waste glass as partial and complete replacement for sand

Abstract The sustainable benefits of waste glass usage in concrete include the possibility of reducing solid waste and greenhouse gas emission and preservation of raw materials. This current study examines the effect of recycled waste glass as a partial and complete substitute for natural sand in producing eco-friendly concrete. The recycled waste glass was proportioned in levels of 25, 50, 75 and 100% by weight to substitute sand in the concrete using a mix ratio of 1:2:4 (cement:sand:gravel) at a W/C ratio of 0.5 targeting 20 MPa strength at 28 days. Tests, which include X-ray fluorescence (XRF), were conducted on the waste glass and cement materials; slump test was performed on the freshly prepare concrete at different percentage glass content. Compressive and tensile strength tests were performed on 60 specimens after 3, 7, 28 and 90 days of curing. The concrete microstructure was examined using the scanning electron microscope (SEM). Results showed that workability and the mechanical strength of the concrete produced decreased with increasing waste glass content. However, concrete containing 25% and 50% waste glass contents showed significant enhancement in strength, but it is recommended that the optimum glass content should be 25% for the production of sustainable eco-concrete.

Sawdust Stabilization of Lateritic Clay as a Landfill Liner to Retain Heavy Metals

Compacted clay soils are commonly used as landfill liners. This research work was aimed at investigating the suitability of sawdust amended lateritic clay as a landfill liner to adsorb Pb and Cd, thereby protecting underground water. Index properties, compaction, strength and permeability tests were conducted on the unstabilized and stabilized clay in order to determine the effects of the sawdust on the geotechnical properties of the lateritic clay. Batch kinetics tests were utilized to determine the capacity of the clay and sawdust-amended clay to adsorb Pb and Cd. The soil, classified as A-7-6 and CH by AASHTO and unified soil classification systems, respectively, was admixed with 0%, 5%, 10%, 20%, and 30% sawdust by dry weight of the soil. Test results show that the specific gravity, plasticity index, maximum dry unit weight and unconfined compressive strength of the soil decreased with increasing sawdust content while the optimum moisture content and hydraulic conductivity increased with increasing sawdust content. The stabilization of the lateritic clay with ≤10% sawdust content was recommended for use as landfill liners, as they meet the standard hydraulic conductivity requirement and present a good adsorption of Pb and Cd.