Julius M. Ndambuki

Consumption of sachet water in Nigeria: quality, public health and economic perspectives

Demand for drinking water is met by different methods in different parts of the world. Water packaging into polyethylene sachets (as a form of water vending) has assumed an innovative status which has spread from its origin in Nigeria to other West African countries. This research examined the factors that birthed this product and the problems associated with sachet-packaged water (SPW) by reviewing relevant literature. In addition, 11 SPW samples were randomly procured from Oshodi/Isolo-Ota Expressway in Lagos and Ogun States of Nigeria, and analysed for contaminants. The analysed parameters include turbidity, total dissolved solids, nitrate and sulphate, which were found to be within the safe limits of the Standards Organisation of Nigerias (SON) 5 NTU, 500 mg/l, 50 mg/l and 100 mg/l respectively in all the 22 SPW samples. Other tested parameters such as pH, hardness, cadmium and iron, however, were found to exceed the SON limits of 6.5–8.5, 150 mg/L, 0.003 mg/L and 0.3 mg/L respectively in some of the samples. It was concluded that in spite of the challenges associated with SPW, the product has export potential and could be a water supply solution in water-stressed situations such as refugee camps around the world.

Influence of fly ash, ground-granulated blast furnace slag and lime on unconfined compressive strength of black cotton soil

Utilisation of industrial waste products with black cotton soil (BCS) in the improvement of its engineering properties has gained attention to the sustainability of the natural resources and cost efficiency. This paper evaluates the influence of fly ash, ground-granulated blast furnace slag and lime at 12%, 8% and 1–9%, respectively, on BCS obtained from the N4 road North West Province, South Africa, to improve the soil. The performance of the modified BCS cured for 7, 28, 60 and 90 days was evaluated using compaction, California bearing ratio (CBR) and unconfined compressive strength (UCS) test according to standard specifications. The CBR value increases with increase in the level of compaction. The influence of the waste materials added for different compaction levels and curing periods improved the CBR and UCS values significantly. UCS of the stabilised BCS meets with the specification for sub-base material at 97% and 100% compaction for all the curing periods.

Effect of Gum Arabic karroo as a Water-Reducing Admixture in Concrete

Concrete is one of the most popular construction materials in the world. Chemical admixtures are ingredients added to concrete to enhance its properties. However, most chemical admixtures on the market today are expensive, thereby making them out of reach for small consumers of concrete. In Africa, use of chemical admixtures is rare despite the harsh weather conditions. In the current study, Gum from Acacia karroo (GAK) was used as a water-reducing admixture in concrete. A slump test, density and compressive strength were studied using different dosages of GAK while neat concrete was the control. Results showed that slump increased by 200% at a 2% dosage of GAK. This enabled reduction of water-to-binder (w/b) ratio from 0.61 to 0.48 for samples with a 3% dosage. Reduction in w/b resulted in increased compressive strength of 37.03% above the control after 180 days of curing for a 3% dosage. XRD studies also showed a decreased rate of hydration in the presence of GAK in concrete. It was concluded that GAK can be used in concrete as a water-reducing admixture, which is environmentally-friendly, thus producing sustainable and greener concrete.

Application of Waste Glass Powder as a Partial Cement Substitute towards more Sustainable Concrete Production

Use of waste materials in concrete is now a global trend for efficient waste management so as to achieve a sustainable green environment and with the added advantages of preserving the natural resources as well as producing a better performing concrete. This study examined the properties of concrete containing ground waste glass powder (GP) as partial replacement for cement. The waste glass was finely grounded into powder and the morphology imagery of the powder materials was carried out using scanning electron microscopy (SEM). Moreover, the chemical composition of the glass powdered material was determined using X-ray fluorescence (XRF). Laboratory tests were carried out to determine the strength activity index, workability, split tensile and compressive strength properties of the concrete with 0%, 15%, 18%, 21%, 24%, 27% and 30% partial replacement of cement with the ground waste glass powder. The results showed that the oxides composition of the glass powder meets the requirements for pozzolanic material, while the SEM morphology shows materials of amorphous flaky solid masses, and based on the 28-day strength activity index, concrete containing 21% cement replacement shows a higher strength index above therecommended 75%. It was also observed that workability of the concrete reduced with increase in percentage glass content while significant improvement of the compressive strength of the concrete was achieved at 21% cement replacement, after which a decrease in strength with increasing percentage glass content was observed. The revealed results were confirmed by the microstructural examination using SEM showing a denser concrete at 21% cement replacement but increase porosityas the glass content increases. However, a decrease in split tensile strength was observed with increasing glass content. The results clearly showed that it is possible to produce moderate strength sustainable concrete for structural application using 20% glass powder as cement replacement.

Appraisal of access to safe drinking water in southwest Nigeria

The importance of developing effective water supply services is universally recognised as a basis for improving the overall health of the population. This study ascertained the quality of water supplied by a water treatment scheme in southwest Nigeria. One hundred and twelve samples were collected during the wet and dry seasons. Tests on physico-chemical and bacteriological parameters were conducted. Statistical analysis of variance was carried out on the results of the test. The effectiveness of the treatment processes on the parameters considered showed that the aeration, sedimentation and filtration processes were 70.13% effective in colour removal; sedimentation and filtration processes were 94.78% effective in turbidity removal; sedimentation and filtration process were 28.84% effective in the removal of total suspended solids (TSS) and 9.88% effective in the removal of total solids (TS); the disinfection and filtration processes were 100% effective in bacterial and coliform removal. The treatment system was found to be 71.38% effective in pollutant removal.

Structural Properties of Concrete Containing Ground Waste Clay Brick Powder as Partial Substitute for Cement

With the increasing concerns on the impact of cement production on the environment and the need to protect the environment, the use of mineral additives as cementitious material to partially substitute cement is being considered as an effective option. One of such material is fired clay brick which can be sourced as generated waste from clay brick industry. This has an added advantage of reducing industrial waste and preserving the natural resources. The experimental objective of this study is to examine the possibility of utilizing clay brick waste as partial replacement for Portland cement in concrete. The clay brick was finely ground into powder size, and after grinding, the morphological characterization of the powder materials was carried out using scanning electron microscopy (SEM). Moreover, the chemical composition of the brick material was determined using X-ray fluorescence (XRF). Laboratory tests were carried out to determine the workability, split tensile and compressive strength properties of the concrete with 0%, 10%, 20%, 30% and 40% partial replacement of cement with ground clay brick (CB). From the test results, the chemical composition of the brick powder meets the standard requirements for pozzolanic material, with the SEM revealing an amorphous solid mass. The workability of the concrete reduces with increase in brick powder content. A significant improvement of the split tensile and compressive strength of the concrete was achieved at 10% cement replacement, after which a decrease in strength with increasing ground clay brick content was recorded. The use of ground clay brick of not more than 15% was recommended for concrete production.

Effect of Substitution of Crushed Waste Glass as Partial Replacement for Natural Fine and Coarse Aggregate in Concrete

Reusing of waste glass in concrete production is among the attractive option of achieving waste reduction and preserving the natural resources from further depletion thereby protecting the environment and achieving sustainability. This present study examines the possible reuse of waste glass crushed into fine and coarse aggregate sizes as partial substitute for natural fine and coarse aggregate in concrete. The variables in this study is both the fine and coarse aggregate while the cement and water-cement ratio were held constant. The crushed glass was varied from 0 – 100% in steps of 25% by weight to replace the both the natural fine and coarse aggregate in the same concrete mix. Concrete mixes were prepared using a mix proportion of 1:2:4 (cement: fine aggregate: coarse aggregate) at water-cement ratio of 0.5 targeting a design strength of 20 MPa. Tests were carried out on total number of 90 concrete cube specimens of size 150 x 150 x150 mm and 90concrete cylinder specimens of dimension 100 mm diameter by 200 mm height after 3, 7, 14, 28, 42 and 90 days of curing. Test results indicated that the compressive and split tensile strength of the hardened concrete decreases with increasing waste glass content compared with the control. However, concrete mix made with 25% waste glass content compared significantly well with the control and can be suitably adopted for production of light weight concrete.

Characterization of ceramic waste aggregate concrete

Abstract There is a growing interest in using waste materials such as ceramics as alternative aggregate materials for construction. While other ceramic product wastes such as sanitary wares and electrical insulators have been extensively investigated, not much findings are available on ceramic wall and floor tiles wastes. Thus, the current study focuses on the mechanical characterization of waste ceramic wall and floor tiles aggregate concrete. Ceramic wastes sourced from construction and demolition wastes were separated from other debris and crushed using a quarry metal hammer. Ceramic tiles were sieved into fine and coarse aggregates in line with standards. Other materials used were gravel, river sand, cement and potable water. Workability of the fresh concrete was checked through slump test, and concrete cubes of 150 mm dimensions and cylinders of 100 mm × 200 mm were cast in the laboratory. After 24 h of casting, the concrete samples were demolded and were cured by immersion in water tank at temperature of 22 °C. The compressive and split-tensile strengths of the hardened concrete samples were determined after curing them for 3, 7, 14 and 28 days. Results showed that both the compressive strength and split tensile strength increased appreciably with the curing age than the conventional concrete.

Development of a Water Treatment Plant for Heavy Metal Adsorption

Advantages of adsorption method for the removal of heavy metals from drinking water are abundant in literature. However, there is little information on the practical application of this knowledge at domestic level. Middle and high income earners can afford more expensive heavy metal treatment technologies. Low income earners, however, are often exposed to heavy metal contaminated water. This study, therefore, demonstrates how a cheaply fabricated water treatment plant (WTP) can be used with discarded automotive tire (DAT) to remove metals from drinking water. Drinking water samples from borehole and river sources which were slightly acidic and contained metals such as chromium, aluminum, manganese, calcium, zinc and copper was placed in the WTP. Crushed DAT was added to the water and stirred at a rate of 110 revolutions per minute for ten minutes at room temperature. Results show that the use of DAT in the WTP improved pH by 8-9% while TDS improved by 41-27% in ground and surface water samples respectively. Also, copper, chromium, aluminum, and manganese improved by as much as 46%, 5.5%, 50% and 25% respectively in some water samples. The paper concludes by recommending that other adsorptive materials can be tested for use in the WTP.

Application of hydraulic modelling to control intrusion into potable water pipelines

A key objective of water supply systems is to provide potable water to consumers at an appropriate quality, however, through distribution networks, water quality can be compromised. One of the avenues through which this can happen is contaminant intrusion into the network. Through hydraulic modelling, this paper examines how potential intrusion into water distribution networks can be established and also predicts the magnitude of intrusion that is expected to occur, given particular conditions. The paper further suggests possible preventive measures that can be taken in order to avert the occurrence of this phenomenon. Results indicate that for potable water pipelines flowing through high pressure areas, if the pressure of the surrounding environment can be established then by ensuring that network pressures are above the surrounding pressures in those sections of the network, intrusion can be overcome.