The impact of activity-based method on the performance of Science learners from selected junior secondary schools in Nigeria

The study investigated the Impact of Activity-Based Teaching Method (ABTM) on students’ academic performance in basic science at Junior Secondary Schools in Katsina Metropolis, Nigeria. Three research questions and three research hypotheses were formulated to guide the researcher in the conduct of the research. The study randomly sampled three hundred and thirty (330) out of nine thousand and six (9,006) Junior III Basic Science Students. Three of the randomly selected schools were placed as experimental control groups. A total of one hundred and sixty five (165) students were randomly sorted out, each way, to constitute the experimental and control groups. A quasi-experimental pre-test-post-test research design was used for the study. A pre-test was administered to ascertain the equivalence of the two groups. The study subjects in the experimental group were taught a number of concepts enshrined in environmental management for sustainability using the assets in activity-based teaching method; the control group was taught the same content using the lecture method for eight weeks. The students were subjected to “Basic Science Achievement Test” (BSAT); this instrument provided data for addressing the research questions and hypotheses raised in the study; the hypotheses were tested using SPSS version 20.0 packaged at 0.05 level of significance; t-test for independent samples was used to test the hypotheses. The study revealed that basic science students taught using activity-based teaching strategy performed significantly higher than their counterparts who were only taught using lecture method; similarly, there was significant difference in the academic performance of males, as compared to female students; similarly the students exposed to activity-based teaching strategy demonstrated a higher retention ability indices in the learning of basic science concepts, as compared to their colleagues who were exposed only to the lecture method. The study recommended that teachers should employ activity-based teaching methodology (ABTM) in teaching concepts in basic science at Junior Secondary Schools in order to enhance academic performance and retention of the content that was taught. The study further recommended that there should be provisions in schools of facilities, provisions and equipment which are vital for effective implementation of activity-based teaching method (ABTM).Curriculum and Instructional StudiesD. Ed. (Didactics

Recycling of construction and demolition waste (CDW) towards sustainable beneficial outcomes

Abstract: Population growth, industrialization and infrastructure development have continued to result in large amounts of construction and demolition waste (CDW) been dumped in landfills. The various enormous construction, demolition, remodeling, restructuring, renovation and repairs on domestic and industrial buildings as well as projects on infrastructure growth generate vast amounts of CDW considered low risk but of high volume. In South Africa and other African countries, CDW often ends up in landfills for lack of feasible recycling and reuse options. Considering the quantity of CDW insistently generated, it is expected that these wastes are converted to wealth if appreciated as useful resource for energy recovery, recycling or reuse. The need for recycling and reuse alternatives have increased in recent years with pressing concerns on the impacts of landfill disposal of CDW on the environment and human health. Irrespective of growing concerns, it is clear that landfilling will remain the main waste management disposal system for CDW in the foreseeable future. Hence, the study pinpoints the importance of recycling and reusing CDW towards beneficial outcomes. CDW can be profitably harnessed if properly sorted, crushed and sieved using the cheapest appropriate technology possible for concrete works. If well established, recycling and reuse alternatives can be efficiently implemented by incorporation into concrete technology with keen eyes for low cost housing schemes for social benefits

Diffusion in saturated clayey barrier medium

Abstract: The design of clay/clayey barriers for the containment of buried wastes conventionally has been based on the assumption that the hydraulic conductivity controls the rate of leachate percolation. However, recent studies show that diffusion is a controlling mechanism of solute transport in many fine-grained soils. Although the measurement of the hydraulic conductivity of finegrained soils is comparatively a common practice in soil engineering, the measurement of diffusion coefficients is not. As such, it is becoming increasingly essential to assess the movement of chemicals through soil barriers due to diffusion. Studies indicate that diffusion may be an important, if not dominant mechanism of contaminant transport through waste containment barriers. This paper is therefore in line with the efforts made in the measurement of diffusion coefficients of inorganic chemicals passing through saturated soils. Herein, both steady-state and transient equations relating to the diffusive transport of inorganic chemicals are presented. A number of factors affecting diffusion coefficients are identified and a simple method for measuring diffusion coefficients for a compacted barrier is defined. The definition for the diffusion coefficient of soil called the effective diffusion coefficient, D* is seen to vary widely. Generally, the variations are due to the different factors affecting diffusion of solutes in soil and the various ways of including the volumetric water content in the governing equations. Hence, errors in interpretation and comparison of D* values can occur if the appropriate definition is not used. In a nutshell, the concept of diffusion may be unfamiliar to many soil specialists, worsened by the myriad terminologies linked to the study of diffusion in soils. Thus the study attempts to acquaint soil engineers with vital information for the measurement of diffusion coefficients for barrier designs

Transformation and utilization of agricultural waste as component of green concrete for rural housing and development schemes

Abstract: Several researchers have outlined cost saving and cement blending merits without compromising standards. As such, utilizing artificial pozzolana as supplementary cementitious materials (SCMs) in concrete engineering is well known. However, there is continual search for substitute materials. The use of Rice Husk Ash (RHA) as cementitious constituent in green concrete was studied. Its abundance paved way for the study to look into the compressive strength of the concrete type formed by partly substituting Ordinary Portland Cement (OPC) with RHA under short curing series. Analysis on RHA revealed significant properties of pozzolanic hardening. 60 cubes of 100 mm dimensions were cast with cement replacement by RHA ranging from 0-40% while adopting a 28 day targeted strength of 25 MPa as control. The cubes were cured at relative humidity (RH) of 95-100% and temperature (T) of 22-250C in a chamber for periods of 7, 14, 21 and 28 days. The outcomes displayed trends of strength gain, reduced density and compressive strength with increase in RHA. The 28 days density and strength of the normal concrete was 2465 kg/m3 and 28.57 MPa while the 10% RHA sample (i.e. best substitute matrix) had 2398 kg/m3 and 25.97 MPa respectively. The strength of 10% RHA/OPC concrete (25.97 MPa) was slightly higher than the adopted strength (25 MPa) at 28 days. This signifies its suitability as concrete constituents and can be a major cost reduction factor in rural shelter projects where less structural complexities are required. Hence, it can be employed in the construction of simple foundations and concrete composites

Palm kernel incinerated ash as low cost concrete component

The incorporation of commercially available fly ash (FA) as low cost material in concrete has long been established. Large quantities of FA are utilized for research and field applications because of the pozzolanic characteristics. One of many pozzolanic materials is palm kernel incinerated ash (PKIA). The abundance of PKIA as an agricultural waste material in West Africa obtained by the incineration of palm kernel husk and shells in milling boilers paved way for this study. Specimens containing 50%PKIA were cast and cured both in water and air and their compressive strength and shrinkage behaviours were investigated with and without the addition of superplasticizer (hydroxylated carboxylic (HC) acid) in comparison with controlled specimens containing 100%OPC. Results showed that the strength development in PKIA green concrete at all ages of curing; 7,14 and 28 days were lower than OPC concrete. On the addition of superplasticizer, strength of 36.9N/mm2 was observed for specimens with superplasticizer as against 31.7N/mm2 for specimens without superplasticizer on the 28day. The water curing method produced the best results while the predicted shrinkage strain of the green concrete in accordance to ACI 209R-92 standard was higher than the control specimens

Provisional equations for determining leachate leakage rate through composite barriers from compromised geomembrane

Abstract: From years ago to present date the equations available for determining the rate of leachate leakage through composite barriers from geomembrane (GM) failures necessitated the use of graphs to attain the value of one of the terms of the equations for the case where the leachate head is larger than the thickness of the low-permeability soil medium of the composite barrier. This work reveals that the terms requiring graphs can be expressed analytically, which shows a new set of equations that leads to an entirely analytical approach of determining the rate of leachate leakage through composite barriers. The provisional set of equations is principally beneficial when the leachate level is large as against the thickness of the low-permeability soil medium of the composite barrier. This is usually the case when the low-permeability soil medium allied with the GM to form a composite barrier is a geosynthetic clay liner (GCL). Whether the failure in the GM is small or large or where the leachate level on top of the barrier is large as against the thickness of the low-permeability soil layer of the composite system, a provisional equation can be used to determine the leakage rate through the system. Although in such a scenario, graphs are essential in attaining the value of one of the terms of the equations. Therefore, this paper shows that the graphs can be replaced by equations, which proceeds to the generation and utilization of an entirely analytical method of determining the rate of leachate leakage through a failed composite waste containment barrier, irrespective of the leachate level overlying the system

Mechanical properties of green concrete with Palm Nut Shell as low cost aggregate

The cost saving benefits of aggregate replacement in concrete works are well documented. The utilization of Supplementary Aggregate Materials (SAMs) in concrete engineering without compromising standards in concrete works remain very attractive to both infrastructure developers and design engineers. However, there is continual search for low cost beneficial substitute materials. The mechanical properties of green concrete produced from Palm Nut Shell (PNS) as coarse aggregate was investigated. The abundance of PNS (light weight waste product of palm oil production) in West Africa created the impetus for the study. Series of laboratory tests such as; Slump, Compaction factor, Density, Schmidt hammer and Compressive strength tests were conducted on specimens of 10, 20, 30, 40 and 50% replacements of dry weight of PNS as coarse aggregate and specimens of natural aggregate as control sample. The specimens were cured at relative humidity (RH) of 95-100% and temperature (T) of 22-25oC in a chamber for periods of 7, 14, 21 and 28 days. The results showed the PNS samples to have relatively medium to high workability ranging from 24-47 mm for slump height and values of 0.85 to 0.90 for compaction factors. A general strength development was observed across the different samples with the PNS sample reaching strength of 48.7 N/mm2 at 28 days curing. The 50% replacement specimens which mobilized UCS of 28.7 N/mm2 met the requirement for lightweight concrete however, 30% is the optimum for a partial aggregate replacement in green concrete as UCS of 39.2 N/mm2 was mobilized in 28 days. Thus PNS is a suitable concrete constituent and can be a major cost reduction factor especially in low cost rural projects with streamlined loading requirements

Special Issue: Comparative assessment 1 of compositing and anaerobic digestion of 2 municipal biodegradable waste in Harare, Zimbabwe

Abstract : Composting and AD of biodegradable waste were assessed for their benefits from literature and environmental impacts using the life cycle impact assessment procedure. Literature review findings indicate an overall edge for AD over composting largely due to its renewable energy production capabilities, reduced exhaust emissions and cost effectiveness considering the entire MSW life cycle. LCIA results show that both AD and composting leads to increases across the four impact categories considered namely, global warming, human health, eutrophication and acidification. AD however showed lower contributions than composting to global warming, human health and acidification. Composting only showed lower contribution than AD in regards to eutrophication. Overall study results indicate an edge for AD over composting in treating and managing biodegradable fraction of MSW generated in Harare and its surrounding urban and peri urban environments of Chitungwiza, Epworth, Norton and Ruwa

Engineered geo-composite liner : an empirical look at contaminant travel through a circular punctured defect in a lining system

Abstract: Small-scale laboratory tests on the effect of contaminant travel in geo-composite liners through circular punctured geomembrane were conducted in a modeled device. The influence of pressure on contaminant flow rate, contaminant transport and the buffering ability of natural soil profile were investigated. Flow through the geo-composite liner-buffering profile (BP) system was measured for tests with the punctured geomembrane under loads of up to 150 kPa. Results and analysis showed significant reduction in flow rate with increased pressure on the system. This reduction is attributed to the reduced barrier system transmissivity, θ and soil liner compressibility. The flow rate data for tests with geomembrane in this study were compared with predicted values using equations from Forchheimer (1930) and Giroud et al., (1989). The comparison showed inapplicability to this study and in practice if perfect contact conditions at the geomembrane/soil interface are assumed. However, equations from Giroud (1997) for good contact conditions gave reasonable flow rate predictions through punctured geomembrane of geo-composite liners

Chemical alterations in three clayey soils from percolation and interaction with acid mine drainage (AMD)

Abstract: The issues of acid mine drainage (AMD) from mining activities is not a new phenomenon to the present day developing South Africa as well as in most developed countries around the globe. However, the persistent rise in environmental contamination in South Africa is drastically attracting massive concerns. Vital concerns of AMD in South Africa still remain the threat to soil, surface, subsurface and ground water reserves among others, which consequentially impact human and environmental health. This insistent challenge has given rise to the need for investigating the buffering efficacy of clayey mineral soils for use as natural contaminant barriers to contaminant species from AMD. Therefore, the study presented herein, was channeled towards assessing the chemical alterations in three clayey soils from permeation and interaction with AMD via successive protracted percolation up to 18-25 pore volume passage of AMD through the respective soil medium. The final hydraulic conductivity measured, ranged between 1.3 × 10-11 m/s and 1.5 × 10-11 m/s. The obtained pH, electrical conductivity and solute breakthrough curves indicated the soils had low acid-buffering efficacies. Chemical species such as Na, Co and SO42- were highly dissolved due to attack on the soil grains by AMD. Chemical species were also released from the soils including the dissolution of metals and desorption of chemical species from AMD attack. As such, the study revealed that the buffering efficacies of the respective tested clayey soils to AMD chemical contaminants were generally ineffective