A. N. Ede

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.

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.

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.

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.

Life Cycle Assessment of Environmental ImpactsofUsing Concrete orTimber toConstruct aDuplex Residential Building

Traditionally, the choice of construction materials depended principally on the strengths of materials, cost of material, availability of materials, simplicity of erection, aesthetics and technical expertise available to the society. This meant that little attention was paid to the environment impacts of materials adopted for civil construction. After centuries of speedy advancement accompanied by deteriorating ecosystem as evidenced by the global climate change and the accompanying gap between the rich and the poor, the world is becoming more conscious of the ecosystem and the future of mankind. This has led to the growing quest for sustainable development. In the more recent years, environmental and sustainability factors are becoming compelling factors in the choice of construction materials. Researches focused on materials for affordable houses for the increasing low income masses are on the increase. This research focuses on the environmental impact performance of concrete and timber applied to a modest duplex residential building. It explores using Athena Impact Estimator software to model the greenhouses gases expressed in terms of carbon dioxide equivalents, sulphur dioxide equivalents, phosphate equivalents and ethane equivalents potentials obtainable from using concrete or timber to build a duplex residential building. From the various results obtained, it is very evident that timber construction is more eco-friendly in terms of carbon emission reduction which translates to reducing global warming, thermal insulation and energy efficiency. This will be helpful in making choice for building materials to be adopted for affordable houses developing countries.

Economic Exploitation of Gravel in Place of Granite in Concrete Production

The paper investigated the application of gravel as partial economic replacement of granite in concrete production. Concrete was produced using granite/gravel combination in varying percentages of 90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80 and 10/90. Concrete made from 100 % granite and 100 % gravel served controls while other constituents of concrete were kept constant. Two different mix ratios of 1:2:4 and 1:3:6 were employed. Sieve analysis was carried out on the aggregates, while slump and compaction factor tests were carried out on fresh concrete. Compressive strength tests were performed on hardened concrete. Specimens were produced using 150 mm cubes for compressive tests. The reliable percentage of granite/gravel combination from compressive strength view point 60/40 with a value of 21.15 N/mm2 for mix ratios 1:2:4 and 70/30 with 15.17 N/mm2 for 1:3:6 mix ratio at 28 days. Satisfying respectively the 20 N/mm2 and 15.17 N/mm2 minimum requirement of BS 8110: 1997.There were costs saving of 4 % per unit volume of concrete production for both 1:2:4 and 1:3:6 respectively. Empirical evidence from the regression analysis revealed that higher composition of gravel significantly improves the concrete consistency properties while greater proportions of granite do significantly enhance comprehensive strength.

Optimal Polypropylene Fiber Content for Improved Compressive and Flexural Strength of Concrete

Worldwide, concrete is a very important construction material, impacting heavily on Gross Domestic Products of many nations: a

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

30 billion business for ready- mix concrete production industry per year in the United States and a cement consumption rate of about 106kg per person in Nigeria. It is therefore imperative that this important material in the world construction industry must also be endued with the best possible properties. The principles on which reinforced concrete structural designs were based hangs on quality concrete material used in conjunction with quality steel or reinforcing material. However, in Nigeria, the reinforcement steel commonly used is of poor qualities as recent researches have shown that over 40% of 12 mm and 16 mm used within Lagos in 2010 failed the 460N/mm2 yield strength bench mark of BS8110 of 1997. The employment of micro fibers in the concrete will improve the strength and compensate for the apparently declining strength of Nigerian reinforced concrete building constructions and will also improve the strength of the non-reinforced concrete-sand crate block buildings. This research studies the effects of micro synthetic polypropylene fiber in improving concrete strength with the main focus of identifying the optimal quantity for improved compressive and flexural strengths of concrete. Destructive and non-destructive compressive strength tests and destructive flexural strength tests were carried out on the samples built with 0.25%, 0.5% 0.75% and 1% contents of polypropylene fibers alongside a control samples after 7, 14, 21 28 days of curing. The optimal percentage of polypropylene fiber that produced improved compressive and flexural strengths were found to lie within 0.25% and 0.5%.

Structural Damage Assessment of FRP Strengthened Reinforced Concrete Beams under Cyclic Loads

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.