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 Modeling The Tensile Strength Of Concrete With Polyethylene Terephthalate (Pet) Waste As Replacement For Fine Aggregate Using Artificial Neural Network(2022) AJAGBE W.; Tijani M.; Oluwafemi O.Tensile strength of concrete made with polyethylene terephthalate (PET) waste as replacement for fine aggregate was modelled using artificial neural network. A multilayer feedforward neural network (MLFFNN) and radial basis function (RBF) methodology were compared to see which was more accurate. The MLFFNN modelling results showed a predictive accuracy of 95.364% and a root mean square error value of 4.4409 × 10-16 while RBF neural network modeling results showed a higher predictive accuracy (99.509%) with a lower root mean square error value (1.6653 × 10-16). It is concluded that ANN models accurately predicted the tensile strength of PET concrete.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 Combined reusing of sorghum husk ash and recycled concrete aggregate for sustainable pervious concrete production(2022) Tijani, M.A; Ajagbe W.O; Oluwole, A.AThe huge amounts of natural resources and high level of energy consumption in concrete production necessitate the use of agricultural and demolition wastes as alternative construction materials. The present study explores pervious concrete (PC) that includes sorghum husk ash (SHA) and recycled concrete aggregate (RCA) as alternatives to cement and natural aggregate (NA) in standard PC mixtures. PCs were prepared from mixtures derived from replacement levels 0%, 5%, 10%, 15%, 20% and 25% of cement with SHA and 0%, 20%, 40%, 60%, 80% and 100% of NA with RCA. The density, compressive strength and hydraulic properties (void ratio and hydraulic conductivity) of the samples were determined at 28-day using ACI standards. Sustainability efficiency of incorporating SHA and RCA on PC was also investigated using structural efficiency and carbon dioxide (CO2) emission. Their cost effectiveness was equally examined. Results revealed that densities of PC decreased with increase in SHA and RCA amount. Compressive strength and structural efficiency reduced with increase in SHA except at 5% where they were higher than the control. On the other hand, the incorporation of RCA decreased the compressive strength but improved the PC hydraulic properties. CO2 emission and production cost were found reduced with increase in SHA as well as RCA. The maximum reduction of CO2 emission (38.23%) and production cost (51.29%) were obtained when 25% SHA was combined with 100% RCA. The combined usage of SHA and RCA as raw materials in PC was found to be effective in boosting PC’s hydraulic properties at an appropriate compressive strength. The reduction of CO2 discharge and in production cost attributed to the construction materials demonstrates their impacts on mitigating global warming problems and lowering costs of PC production.Item Evaluation of Thermal Effects on Slag Cement Concrete’s Strength Properties(2022) Ajagbe W.; Terlumun S.; Tiza M.The physical, chemical, and mechanical characteristics of concrete change with heat-fire. The effect of thermal load on Slag cement concrete output must be measured because of the crucial role of thermal resistance in concrete structure performance and operation. This work examines the thermal resistance of Slag cement concrete. The concrete cubes were produced and cured for 28 days and then subjected to varying temperatures range of 100°C, 150°C, 200°C, 250°C, and 300°C. Hardness and compressive strength were measured at 30, 45, and 60 minutes; the sample results were compared to those of ordinary Portland cement used for the study. The findings of this experiment demonstrate that strength loss was 0.45% at 100 °C, 1.75% at 150 °C, 2.67% at 200°C, 5.98% at 250°C and 12.04 % at 300 °C, the hardness property increased from 100° to 150°C but decreased with higher temperatures. However, average concrete loss at 300 °C exceeds 20 percent of its compressive strength. This means that higher temperatures have adverse effects on concrete strength. From the test, however, it has been noted that there was an insignificant loss of strength of concrete at temperatures below 250°C and however, above 250 °C, a significant loss of concrete strength was observed. The results indicate that slag concrete has a significantly higher thermal resistance potential than traditional concrete and can be used even in industrial applications.Item Investigating The Fracture Characteristics Of Nigerian Rice Husk Ash (Rha) - Based High Strength Concrete (Hsc)(2020) Bucknor, A.O.; Fisayo, M.A.; Olutoge F.A.; Adewtayo, O.A.; Ajagbe, W.O.; Ikponmwosa, E.E.Based on the initial research on the suitability of RHA in partial replacement of cement in HSC production, it was observed that between 10 - 20% replacement by weight of cement with RHA shows potential for use in the production of HSC based on their compressive strength. However, However, the use of compressive strength criteria only as a determinant in High Strength Concrete (HSC), especially in RHA-Cement blend concrete, has shown its inadequacies. Fracture Mechanics is a reliable experimental/analytical tool that has not been adequately used in the study of RHA-based HSC. Thus, the need to study its fracture mechanics parameters such as Crack Tip Opening Displacement (CTODC) test and Stress Intensity Factor (KSIC) to understand the behaviour of the RHA-based HSC to fracture toughness which is an indication of the strength of concrete when subjected to loading. Milled samples of the RHA were used in the preparation of RHA- Cement blends with the cement being replaced at 0%, 10% and 20% by cement weight. The 0% replacement served as a control for the experiment. 36 cubes of HSC with an expected compressive strength of 60MPa respectively were produced; 12 cubes for each percentage replacement aimed at affirming the compressive strengths were within the expected 60 MPa value. Then same mix design was used to prepare 78 beams (18, 30 and 30 for 0%, 10% and 20% RHA-Cement blend HSC) were prepared and subjected to experimental Fracture Mechanics three-point bending tests (TPBT) while the peak load for each beam before failure were recorded. The recorded peak loads were used to develop function via numerical computational and statistical models to determine the and values for the concrete. Based on the numerical analysis done, there was a progressive increase in CTODC and KSIC with an increase in RHA content in the concrete mixes with 20% having the highest C T OD c and Kfc (1 .4 1 9 7 M P aVm and 0 .0 3 1 7 m m) values compared to the control and the 10% RHA. Thus, it implies 20% RHA-cement blended HSC has more resilence compare to the 10% RHA.Item Effect of Waste Polymer Modified Bitumen with Milled Corn Cob as a Partial Replacement for Filler in Asphaltic Concrete(2020) Ajagbe W.O.; Salami L.O.; Akinleye M.T.; Salami M.O.There is need to consider the use of cheaper and locally available materials so as to minimize the construction cost for sustainable development. Therefore, this research evaluated the physical and mechanical properties of waste plastic bottles modified bitumen with Milled Corn Cob (MCC) as a partial replacement for filler. Waste polymer was obtained from different waste generation points. A portable gas cooker was used to melt the waste polymer. Corn cob was sun-dried, and milled by an abrasion machine. Also, 60/70 penetration grade of bitumen was used for the study. The bitumen was replaced by waste polymer of 5%, 10%, and 15%. Bitumen modified samples were further prepared by mixing it with MCC of 10%, 30%, and 50%. Penetration, softening point, ductility, viscosity, flash point, fire point, loss on heating, specific gravity, stability, and flow were carried out on unmodified, modified bitumen and asphalt samples. All tests were conducted in accordance with the method of testing established by Indian Standard (IS) specification. Penetration, ductility, viscosity, flash point, fire point values decreases with increase in waste polymer content while softening point and loss on heating increases with increase in waste polymer content. Stability and flow value decreases with an increase in waste polymer and MCC content. The Optimum bitumen content, stability, and flow values for all the samples conform to the acceptable limits specified by Federal Ministry of Works (FMW) (1997) and IS specification. The results indicated an improvement in shear resistance, increment in resistance to deformation and optimum modifier content was found to be 10% for waste polymer and MCC.Item Compressive Strength of Concrete Using Sorghum Husk Ash and Calcium Chloride(2020) Tijani M.A.; Ajagbe W.O.; Ayininuola G.M.; Dahunsi B.I.O.; Agbde O.A.This paper investigated the effects of Sorghum Husk Ash (SHA) and Calcium Chloride (CaCl2) on the compressive strength of concrete. Concrete specimens were prepared by partial replacement of cement with SHA (5, 10, 15, 20 and 25% by weight) and addition of 1% CaCl2 by weight of binder; using a constant mix proportion (1:2:4) and water-to-binder ratio (0.6) for all mixtures. The properties evaluated were slump, density and compressive strength. The result indicated that addition of SHA reduced the slump (concrete turn out to be stiffer) and density of concrete. The 28 day compressive strengths result showed that 0%SHA/1%CaCl2 have the maximum strength of 28.11 N/mm2 followed by 5%SHA/1%CaCl2 (26.45 N/mm2), 10% (25.01 N/mm2), 0%SHA/0%CaCl2 (23.11 N/mm2), 15%SHA/1%CaCl2 (22.45 N/mm2), 20%SHA/1%CaCl2 (20.90 N/mm2) and 25%SHA/1%CaCl2 (18.13 N/mm2). This suggests that the best addition of SHA as fractional replacement for cement in CaCl2 concrete is in the range 0 - 20% since their compressive strength results were above 20 N/mm2 target strength. Incorporation of 1%CaCl2 together with 5 and 10%SHA would yield a concrete of greater compressive strength than standard concrete grade 20.