Civil Engineering
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Item Properties of Hollow Sandcrete Blocks Produced from Ultrafine Carbon Particles Blended Cement(2023) AJAGBE W.O.; TIJANI, M.A.; AJUWON, M.O.This study investigated the properties of hollow sandcrete blocks produced from ultrafine carbon particles (UCP) blended cement. Waste radio batteries were obtained from electronic repairers and dumpsites in Osogbo. The carbon rod in the batteries were sorted and mechanically grinded to UCP. The UCP replacement levels of 1, 2, 3, 4 and 5% were used. A total of 36 hollow sandcrete block specimens of dimension 450 × 225 × 150 mm were cast using mix ratio 1:5 to undergo density, water absorption and compressive strength tests at 7 and 28 days of curing respectively. The densities of the control, 1, 2, 3, 4 and 5% UCP were 1136, 1169, 1152, 1158, 1154 and 1152 kg/m3 at day 7, and 1063, 1093, 1106, 1128, 1134 and 1142 kg/m3 at day 28 respectively. Their respective water absorption were 6.0, 5.3, 5.0, 3.0, 2.8 and 2.0% at day 7 and 12.0, 10.0, 7.0, 6.0, 5.0 and 2.4% at day 28. The water absorption for all the mixtures were within the BS specification of 12% maximum. The 28 day compressive strength increased by 15.48, 19.01, 25.26, 20.52 and 16.47% for 1, 2, 3, 4 and 5% UCP replacement respectively. It is concluded that UCP can be used to improve the compressive strength of sandcrete blocks at acceptable density and water absorption.Item Effect of Variation in Physical and Mechanical Properties of Reinforcing Steel on Post-Construction Parameters of Buildings in Nigeria(2023) AJAGBE W.O.; TIJANI, M.A.; EZENMIA, C.M.; BABATUNDE L.A; GANIYU, A.A.The Nigerian market for construction materials has a problem of standardization as a massive range of variation in construction materials properties plagues the market. A larger number of these variations are below the accepted standards and a key material affected is reinforcing steel. This research aims to investigate the effect of variation in physical and mechanical properties of reinforcing steel on post-construction parameters (cost and safety margins) of buildings in Nigeria. Data on variation of selected properties was collected through extensive literature review and processed into tables showing the result of the input data on key building parameters. Data visualization was done using Microsoft Excel to help gain insights on trends and patterns. The trends and patterns observed informed the regression analysis carried out with Microsoft excel, aimed at establishing relationships between variable variations. A rebar optimization algorithm/software was developed to help optimize variation in standard rebar lengths and reduce waste on site, and was tested on five (5) project cases. The results show a wide range of variation for bar diameter and yield strength values, with some values falling as much as 30% below standard. The variation in young’s modulus was seen to be minimal and has the least effect on safety margins. Equations were generated from regression to predict effect of these variations on safety margins. The rebar optimization algorithm proved efficient in reducing waste and saving cost. The algorithm follows a recursive approach for problem solving. The variation in these properties have a significant effect on building safety and cost. The prediction formulae generated can be used by Engineers to track safety margins and the algorithm can help with waste reduction and cost saving on projects.Item Strength and Abrasion Properties of Mortar Incorporating Groundnut Husk Ash as Partial Cement Replacement.(2023) AJAGBE W.O.; TIJANI M.A.; OLULOPE O.R.This study investigated the strength and abrasion properties of groundnut husk ash (GHA) as partial cement replacement in mortar production. Groundnut husk was burnt to ashes at a temperature of 600°C to obtain Groundnut Husk Ash (GHA) and its chemical composition determined using X-ray florescence analyzer. Preparation of various mixtures of mortar were done by adopting binder/sand ratio of 1:3 and water/cement ratio of 0.5. The percentages of GHA used as replacement for cement varied from 0 - 20% at 5% increment respectively. Fresh pastes were subjected to consistency and setting time tests. Concrete cube, and prism samples were cast and cured for 7, 14, 28, 56 and 90 days and used to evaluate the compressive strength, flexural strength and abrasion resistance of mortar mixtures. The result of chemical analysis of GHA shows that the sum of percentages of SiO2, Al2O3 and Fe2O3 which forms the major oxides for a pozzolanic material was 26.98% and did not satisfied the specification for pozzolans. The GHA pastes had higher consistency and longer setting times than cement. Mortars modified with 5 and 10% GHA had higher compressive strength than the control, especially at later ages. The flexural strength and abrasion loss of mortars reduced with increase in GHA contents with 5 and 10% GHA mortars having comparable results with the control. It is concluded that GHA up to 10% is a good partial replacement of cement in mortar production.Item Recycling sorghum husk and palm kernel shell wastes for pervious concrete production(2022) Tijani, M.A.; AJAGBE W.O.; Agbede, O.A.Agro-industrial by-products are being used as an alternative to traditional building materials because the construction of buildings and roads emits greenhouse gases and consumes energy. This study explores pervious concrete (PC) that includes sorghum husk ash (SHA) and palm kernel shell (PKS) as alternatives to cement and natural aggregate (NA) to obtain a robust, sustainable and cost efficient pavement structure. Mixtures of PC were produced with 5–25% SHA at a level of 5% by weight as substitution for cement and 20–100% PKS at a level of 20% by weight as substitution for NA. The performance of SHA-PKS based PC was evaluated using density, compressive strength, porosity and permeability. Sustainability of combining SHA and PKS on PC was also examined by measuring embodied carbon and energy as well as cost efficacy. Thereafter, Artificial Neural Network (ANN) models to optimize the prediction of porosity and permeability were developed for the PC. Utilizing the coefficient of determination (R2), mean square error (MSE), and root mean square error (RMSE), the suitability of the ANN models was assessed. Results showed that as SHA and PKS amounts increased, PC densities declined. Except at 5%, when they were higher than the control, compressive strength decreased as SHA increased. On the other hand, the addition of PKS increased PC porosity and permeability while lowering density and compressive strength. Mixture of SHA-blended PKS based PC with 40% PKS and 20% SHA attained the compressive strength, porosity and permeability values specified for PC which is adequate for sidewalks and cycle ways. This mixture lowers the embodied carbon, embodied energy and cost by 23%, 20% and 24% respectively. The adopted ANN models adequately predicted the porosity and permeability of PC (R2: 0.99; MSE: 0.88–1.76; RMSE: 0.94–1.32). The findings of this work offer a sustainable path to recycle SHA and PKS for constructions.Item Effect of aggregate type on properties of pervious concreteutajeet(2019) AGBEDE O.A.; AJAGBE W.O.Pervious concrete (PC) is a cheap and effective drainage system for reducing storm-water runoff in urban centers. This research aim to investigate the influence of different type of aggregate on PC properties. Three PC mixtures were prepared with different aggregate types [Granite, Gravel and Recycled Concrete Aggregate (RCA)]. Physical and strength characteristics of the aggregates were analyzed. Density, porosity, permeability as well as compressive strength of PC made with these aggregates were measured. Results showed that PC made from RCA has the highest porosity and permeability due to the porous nature of adhered mortar on RCA. However, highest density and compressive strength was obtained from granite PC followed by gravel and then RCA PC. The study concluded that aggregate type has significant influence on PC properties.Item Modelling the effect of burning temperature and time on chemical composition of sorghum husk ash for optimum pozzolanic activity(2018) AGBEDE O.A.; AJAGBE W.O.Sorghum Husk Ash (SHA) can be used as partial replacement for cement in production of concrete due its pozzolanic behavior. This will reduce the cost and environmental pollution associated with the use and production of cement. The aim of this paper is to model the effect of burning temperature and time on chemical composition of SHA for optimum pozzolanic activity. The testing was done at 2-factors, 5-levels using Central composite design of Response Surface Methodology (RSM). Independent variables considered were: burning temperature (500, 600, 700, 800 and 900oC) and time (1, 2, 3, 4 and 5 hours). Dependent variables (chemical constituents) include: Silicon dioxide (SiO ), Aluminum oxide (Al O ), Iron 2 2 3 oxide (Fe O ), Calcium oxide (CaO), Sulphur oxide (SO ), Sodium oxide (Na O), Magnesium oxide (MgO) 2 3 3 2 and Potassium oxide (K O); all determined using atomic absorption spectrophotometer analysis. The 2 results revealed that the ash content decreases as the burning temperature and time increases. Optimum combined percent of SiO , Al O and Fe O (76.047%) which is the criteria for a good pozzolana was 2 2 3 2 3 achieved at temperature of 700oC and time 3 hours.Item Result Validation Analysis of Steel Testing Machines(2018) AGBEDE O.A.; AJAGBE W.O.Structural failures occur due to a number of reasons. These may include under design, poor workmanship, substandard materials, misleading laboratory tests and lots more. Reinforcing steel bar is an important construction material, hence its properties must be accurately known before being utilized in construction. Understanding this property involves carrying out mechanical tests prior to design and during construction to ascertain correlation using steel testing machine which is usually not readily available due to the location of project. This study was conducted to determine the reliability of reinforcing steel testing machines. Reconnaissance survey was conducted to identify laboratories where yield and ultimate tensile strengths tests can be carried out. Six laboratories were identified within Ibadan and environs. However, only four were nfunctional at the time of the study. Three steel samples were tested for yield and tensile strengths, using a steel testing machine, at each of the four laboratories (LM, LO, LP and LS). The yield and tensile strength results obtained from the laboratories were compared with the manufacturer’s specification using a reliability analysis programme. Structured questionnaire was administered to the noperators in each laboratory to consider their impact on the test results. The average value of manufacturers’ tensile strength and yield strength are 673.7 N/mm2 and 559.7 N/mm2 respectively. The tensile strength obtained from the four laboratories LM, LO, LP and LS are given as 579.4, 652.7, 646.0 and 649.9 N/mm2 respectively while their yield strengths respectively are 453.3, 597.0, 550.7 and 564.7 N/mm2. Minimum tensile to yield strength ratio is 1.08 for BS 4449: 2005 and 1.15 for ASTM A615. Tensile to yield strength ratio from the four laboratories are 1.28, 1.09, 1.17 and 1.15 for LM, LO, LP and LS respectively. The tensile to yield strength ratio shows that the result obtained from all the laboratories meet the code requirements used for the test. The result of the reliability test shows varying level of reliability between the manufacturers’ specification and the result obtained from the laboratories. Three of the laboratories; LO, LS and LP have high value of reliability with the manufacturer i.e. 0.798, 0.866 and 0.712 respectively. The fourth laboratory, LM has a reliability value of 0.100. Steel test should be carried out in a laboratory using the same code in which the structural design was carried out. More emphasis should be laid on the importance of code provisions.Item Structural Investigation into the Causes of Cracks in Building and Solutions: A Case Study(2018) AGBEDE O.A.; AJAGBE W.O.Cracks are commonly found on and in structures and are usually undesirable features naturally occurring due to age, workmanship and other natural and environmental causes. This study is set to characterize cracks with the principal aim of recommending proper maintenance and efficient repair actions. Crack occurrence in an office building (storey with basement) was investigated as a case study. Reconnaissance survey was carried out to locate and note the tools that would be required for the investigation of the cracks. Visual examination and measurement of cracks to know the cause and type of each crack were performed. Strength test of all the structural members was done using Schmidt hammer to determine the residual strength of the members on which they appear and the results were analyzed. The results of the reconnaissance survey revealed that most of the cracks are located at the left side than at right side elevation of the building. The nature of the cracks showed that 91% are dormant cracks, while 9% are active cracks. Some of the cracks extended to the plastered surface, while the rest extended to the structural elements region. Therefore, the cracks in this building were found to be caused by the drying shrinkage at the wall section, the compressive force from the beams exceeding the ultimate strength of the affected blocks, foundation settlement at the courtyard was also discovered through topographical survey, due to underground erosion of the foundation wall footing. The results of the non-destructive test (NDT) indicated that, the average strength of the structural elements is within acceptable limit.Item Effects of Crude Oil Imparted Sand on the Durability of Concrete(2018) AGBEDE O.A.; AJAGBE W.O.A large percentage of soils in crude oil producing areas in Nigeria were contaminated to a varying degree. Past research showed reduction in the compressive strength of concrete made with crude oil impacted sand (COIS). The current effort aimed at assessing the durability of COIS concrete. Soil samples were contaminated with crude oil concentrated levels of 0, 2.5%, 5%, 10% and 15% by weight of sand to produce COIS. Concrete design mix of 1:1.8:2.7 were made with COIS at the different concentrations from which concrete specimen – 100 mm cubes; 100 x 200 mm, and 75 x 150 mm cylinders, were made. COIS concrete were then tested for chloride and sulphate resistance using Electrical Resistivity(ER) test on 100mm x 200mm concrete cylinders and Water absorption (WA) test on 75 x 150 mm cylinders, respectively The COIS concrete was tested for Fire Resistance(FR) by testing the compressive strengths of heated 100 mm cubes. The results showed that COIS concrete exhibited an increased in durability properties as the contamination level increases. The control sample has the lowest value of ER of 119 kohm-cm which indicates low resistance to chloride ion penetration. It also has the highest value of WA of 3.9% indicating low resistance to sulphate attack. However, COIS concrete experienced reduction in strength when exposed to fire as the concentration of crude oil increases. The better durability property of the COIS concrete compliments the strength reduction.Item Assessment of Fine Aggregates from Different Sources in Ibadan and Environs for Concrete Production(2018) AGBEDE O.A.; AJAGBE W.O.Assessment of natural sand being used as fine aggregate for concrete production in Ibadan and its environs was carried out. Ten sources (F1 – F10) were selected for the study; four (F5, F6, F7, F8) were river sand sources while six (F1, F2, F3, F4, F9, F10) were burrow pit sand sources. Samples from each source were subjected to sieve analysis, atterberg limit, bulk density, specific gravity, water absorption, sand equivalent, clay lumps and friable particles, amount of materials passing 75μm and organic impurities adopting ASTM standard procedures. Results revealed that sand from river sources met all the criteria for concrete production stated in ASTM standard while sand from burrow pits deviated from limits of the standard in some respects. F10 had water absorption of 2.6% which exceeded maximum 2% specified, F9 was not free from clay lumps and friable particles with a significant value of 6% as against 3% maximum specification. F1, F2, F3, F4, F9 and F10 have more amounts of materials passing the 75μm sieve ranging from 10.8% for F9 to 20.1% for F10 than maximum of 5% in standard specification while F1, F9 and F10 showed an indication of having organic impurities. It is recommended that performance test be conducted on concrete made from burrow pits sand before use for concrete production. The knowledge of this study can be used as a prospecting tool for selecting suitable sand for the production of quality concrete.