Conference Papers

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Author: search.filters.author.Abubakar, MahmudEnd date: 409

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    Comparison of Drying Shrinkage Models of IOT Concrete
    (Conference: 2nd International Engineering Conference (IEC 2017) Federal University of Technology, Minna, Nigeria, 2017) Oritola, S. F.; Abd Latif, Saleh; Abdul Rahman, Mohd.Sam; Abubakar, Mahmud; Alhaji, B.
    Problems associated with drying shrinkage of concrete is still a major source of concern in the construction industry. Due to the hygral nature of concrete, particularly the instability of the volume as a result of drying shrinkage, concrete will crack at any stage during its service life. The depletion of the environment due to huge consumption of sand for construction is another major problem. Iron ore tailings (IOT), an industrial waste, generated during the production of iron ore is utilized in concrete to lessen the environmental problems. The iron ore tailings was sourced from a local iron ore producing mine and the material was used as partial replacement for sand to produce normal weight concrete. The drying shrinkage of this concrete was compared with that of the control normal weight concrete. The ultimate drying shrinkage of the concrete samples were further studied, using three prediction models. The inclusion of iron ore tailings as fine aggregate in concrete contributed to reduction of the drying shrinkage recorded at 28, 56 and 90 days as well as the ultimate drying shrinkage. The drying shrinkage of concrete and the predicted ultimate drying shrinkage recorded by the B3 and GL2000 models agreed more closely, as compared with the recorded values obtained using ACI209R model.
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    Partial Replacement of Fine Aggregate With Waste Glass in Concrete Made From Bida Natural Aggregate
    (3rd International Engineering Conference (IEC 2019) Federal University of Technology, Minna, Nigeria, 2019) Alhaji, B.; Kolo, D. N.; Abubakar, Mahmud; Yusuf, A.; Abdullahi, A.; Shehu, M.
    This study reports the experimental investigation on the suitability of waste glass as partial replacement for fine aggregate in concrete made using Bida natural aggregates (BNA). Glass is widely used in our daily lives through manufactured products such as sheet glass, bottles, glassware, and vacuum tubing. It is an ideal material for recycling. The increasing awareness of glass recycling speeds up inspections on the use of waste glass with different forms in various fields. Mix ratio of 1:2:4 batched by weight with water - cement ratio of 0.55 was used. The percentage replacement varied from 0% to 40% at 5% intervals. Slump test was conducted to assess the workability of the fresh concrete. The compressive strengths and densities of cured concrete cubes of sizes 150mm x 150mm x 150mm were evaluated at 7, 21 and 28days. A total of 81 concrete cubes were cast and tested. It was observed that an increase in the percentage replacement of fine aggregate with waste glass reduces workability, density and compressive strength. The compressive strength and density vary with days of curing. The findings of this study indicated that the optimum replacement percentage of waste glass with conventional fine aggregate was 20%. However, waste glass can effectively be used as fine aggregate replacement (up to40%) without substantial change in concrete strength.
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    Effect Of Water Cement Ratio On The Compressive Strength Of Revibrated Concrete
    (Environmental Technology and Science Journal, 2015) Auta, S. M.; Abubakar, Mahmud; Yusuf, A.
    Effect of water cement-ratio on compressive strength of re-vibrated concrete is presented. The mix proportion of 1:2:4 aggregates were considered to cast 39 cubes each as laboratory specimen with 0.65, 0.70 and 0.75 water-cement ratios. Each of these categories were revibrated at time lag intervals of 10minutes for 120 minutes period of revibration process and cured for 7, 21 and 28 days. When tested for their respective compressive strength, the result obtained shows that there is a gradual increase in compressive strength of the concrete specimen with increase in time and in water-cement ratio. The maximum compressive strength at 120th minute for ages of 28 days are 25.42, 26.67 and 40.44N/mm2 for concrete with water-cement ratio of 0.65, 0.70 and 0.75 respectively. The maximum attained compressive strength for 28 days curing is 40.44N/mm2 (for 0.75w/c) appears to be higher than 25.42N/mm2 (for 0.65 w/c). Water-cement ratio has adversely enhanced the compressive strength of concrete when re-vibrated.
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    Design of A Composite Traffic Control System at Kpakungu Roundabout Minna, Niger State
    (Nigeria Journal of Engineering and Applied Sciences (NJEAS), 2016) Kolo, S.S.; Adeleke, O. O.; Ayeni, S. J.; Akinmade, T.; Abubakar, Mahmud; Yusuf, A.
    A composite traffic control method is proposed to control traffic and ease congestion especially during peak periods at Kpakungu roundabout in Minna, Niger state. Reconnaissance survey of the roundabout was carried out to note predominant directions of traffic flow from each approach to the roundabout; manual counting of traffic for five working days was done between 7:00 am to 12 noon and 3:00 - 7:00 pm daily. The result of the survey shows that congestion occurs at the roundabout between 7:45 - 9:30 am and between 5:00-6:30 pm every day. Results also show that the peak hourly traffic flow rate occurs between 8:00 and 9:00 am, and 5:00 to 6:00 pm daily. The result of the traffic count was then forecasted for 2-years using data on annual vehicle registration in Minna for 2011 to 2015 obtained from the Niger State Board of Internal Revenue Service. The Webster method of signal timing was used to design traffic signals that will optimally allocate right of way time to conflicting traffic streams. A 5-phase signalization of 90- and 97-seconds cycle lengths were proposed for morning and evening peak periods, respectively.
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    Estimation of Pavement Temperature in Nigeria’s Climatological Zones
    (Proceedings of the Third International Civil Engineering Conference (ICEC, 2024), 2025) Ibrahim, A. I.; Abdulrahman, H. S.; Abubakar, Mahmud
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    Influence Of Roadcem Content on Mechanical Properties of Lateritic Soil for Pavement Applications
    (Proceedings of the Third International Civil Engineering Conference (ICEC, 2024), 2025) Illo, N. A.; Abubakar, Mahmud; Abdulrahman, H. S.; Kolo, D. N.
    Studies on lateritic soil had been carried by numerous researchers across the globe with a view of improving it for the purposes of road pavement and other civil engineering constructions. The main aim of this paper is to examine the impact of varying Roadcem (RC) content on the mechanical properties of lateritic soil for pavement applications which was found to be an A-7-5 soil according to AASHTO. The soil sample was treated with RC at 0, 1,2,3,4, and 5%. Laboratory test such as particles size distribution, unconfined compressive strength (UCS) test for the treated and untreated samples was carried out. Three samples on each dosage were compacted and molded in cylindrical molds and cured two of each sample for 7 days, one each for 28 days. X-ray Diffraction Analysis (XRD), was also carried out on the two samples to reveals their crystalline phases and shows high intensity of CaO and Quartz on the two samples respectively. The UCS results shows insignificant variations in the dosage of RC even at 28 days. The study concluded that A-7-5 soils does not respond to treatment with RC beyond 1% due to its high plasticity and poorly graded and therefore recommend the use of the RC as an additive, at lesser percentage, or on cohesionless soils like sand for road pavement applications.
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    Comparative Assessment of Macroscopic Traffic Flow Properties Estimation Methods: A Case for Moving Car Observer Method
    (ENGINEERING SCIENCE AND TECHNOLOGY INTERNATIONAL RESEARCH JOURNAL, 2017) Abdulrahman, H. S.; Almusawi, A. A.; Abubakar, Mahmud
    Different methods of estimating macroscopic traffic properties is expected to have varying results even when they are carried out on the same road and during the same time interval. A comparative assessment was carried out between traffic data collected at a point and that collected over a short section; Moving car observer method(MCO). Student’s t-test was used to evaluate both data and it was observed that there was no significant difference between them. The MCO method correlates well with conventional data collection method and it can be used as a substitute for it, assuming conventional data collection method is true
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    Comparison of Drying Shrinkage Models of IOT Concrete
    (2nd International Engineering Conference (IEC 2017) Federal University of Technology, Minna, Nigeria, 2017) Oritola, S. F.; Saleh, A. L.; Mohd Sam, A. R.; Abubakar, Mahmud; Alhaji, B.
    Problems associated with drying shrinkage of concrete is still a major source of concern in the construction industry. Due to the hygral nature of concrete, particularly the instability of the volume as a result of drying shrinkage, concrete will crack at any stage during its service life. The depletion of the environment due to huge consumption of sand for construction is another major problem. Iron ore tailings (IOT), an industrial waste, generated during the production of iron ore is utilized in concrete to lessen the environmental problems. The iron ore tailings was sourced from a local iron ore producing mine and the material was used as partial replacement for sand to produce normal weight concrete. The drying shrinkage of this concrete was compared with that of the control normal weight concrete. The ultimate drying shrinkage of the concrete samples were further studied, using three prediction models. The inclusion of iron ore tailings as fine aggregate in concrete contributed to reduction of the drying shrinkage recorded at 28, 56 and 90 days as well as the ultimate drying shrinkage. The drying shrinkage of concrete and the predicted ultimate drying shrinkage recorded by the B3 and GL2000 models agreed more closely, as compared with the recorded values obtained using ACI209R model.
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    Partial Replacement of Sand with Sawdust in Concrete Production
    (3rd Biennial Engineering Conference, Federal University of Technology, Minna, May, 2013, 2013) Abdullahi, A.; Abubakar, Mahmud; Afolayan, A.
    The rising costs of building construction in developing countries have been a source of concern to government and private developers. This study investigated the use of sawdust as partial replacement for fine aggregates in concrete production. Sawdust was used to replace fine aggregates from 0% to 50% in steps of 10%. Concrete cubes measuring 150 x 150 x 150mm were cast and their compressive strengths evaluated at 7, 14, 21 and 28 days. Increase in percentage of sawdust in concrete cubes led to a corresponding reduction in compressive strength values. From the results, the optimum sawdust content was obtained at 10% and its corresponding compressive strength at 28 days is 7.41 N/mm2 which falls within the characteristic strength of plain concrete (7 – 10 N/mm2). This concrete cannot be used for structural applications.
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    Assessment of the Compressive Strength of Concrete Produced with Fine Aggregate from Different Locations in Minna
    (3rd International Engineering Conference (IEC 2019) Federal University of Technology, Minna, Nigeria, 2019) Aminulai, H. O.; Abdullahi, A.; Abubakar, Mahmud; Abdulrahman, H. S.; Alhaji, B.; Joseph, O. F; Aliyu, S. Y
    The construction industry in Nigeria has been witnessing serious collapse of buildings resulting from the qualities of materials used in their construction. This continuous collapse necessitates the need to investigate some of the materials used in the production of the building components in order to ascertain their appropriateness. This research thus investigates the compressive strength of concrete produced using fine aggregate from different locations in Minna. Fine aggregates were obtained from Chanchaga, Maikunkele, Bosso, Lapai Gwari and Garatu areas of Minna and subjected to series of tests namely: sieve analysis, Specific gravity, bulk density, moisture content, and water absorption. Concrete samples were produced using the mix ratio 1:2:4 and the water/cement ratio of 0.6. These samples were subjected to both the slump test and compressive strength test. For each of the fine aggregates, nine cubes of concrete (150mm x 150mm x 150mm) were cast, cured and tested at 7, 14 and 28 days. The results obtained for the mean compressive strength of the concrete produced shows that they all have mean strength greater than 20N/mm2 with fine aggregate from Chanchage having the highest mean of 25.17N/mm2 at 28days of curing. Thus all the fine aggregates could be used in the production of structural lightweight concrete but for structures that require higher strength, the fine aggregate from Chanchaga is recommended