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.