Yazar "Mahdi, Zainab H." seçeneğine göre listele

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  • Kapalı Erişim
    Yayın
    Comparison between mechanical properties of geopolymer and conventional concrete: a review
    (American Institute of Physics, 2026) Mahdi, Zainab H.; Jaber, Firas Kh.; Abdulghani, Ghaith R.; Mohsin, Zainab Mohammed; Wameed, Marthed; Baiyati, Amjed Al
    In this study, geopolymer concrete (GPC) was investigated, as environmentally friendly concrete, on the possibility of using it in buildings and civil constructions compared to conventional concrete. The geopolymer concrete's compressive strength values ranged from 27 to 56 MPa and from 25 to 35 MPa for conventional concrete. The splitting strength is slightly higher than that of conventional concrete. Studies have shown that the values of both the flexural strength and the fracture energy of the geopolymer are higher compared to conventional concrete, while the values of elastic modulus (Young's modulus) of the geopolymer have decreased slightly from that of conventional concrete. Finally, geopolymer concrete has attracted great attention from engineers because of its advantage in that its use reduces emissions of carbon dioxide, cleans the environment of accumulated waste, and produces at a cheap price.
  • Kapalı Erişim
    Yayın
    Evaluation of concrete self-healing by the addition of nano (SiO2+MgO) and (SiO2+MgO) microcapsules
    (American Institute of Physics, 2026) Qasim, Tabarek J.; Moosa, Ahmed A.; Mahdi, Zainab H.; Abdulghani, Ghaith R.; Gou, Guangjun
    This research investigates the effect of the addition of Nano (SiO2+ MgO) on the self-healing behavior of concrete. Also, the impact of microcapsules containing cement with Nano (SiO2+MgO) in the modification of the properties of concrete has been studied. The Nano (SiO2+ MgO) have been added to the concrete mixtures at ratios of (0.3+ 0.2, 0.3+ 0.3, 0.3+ 0.4, and 0.2+ 0.4) % by weight of cement respectively. Then, the compressive strength, density, and water absorption have been measured at ages (7, 14, and 28) days. The results show that the best compressive strength, density, and lowest water absorption have been obtained at the mixture of 0.3% SiO2+0.4% MgO by weight of cement. The concrete samples have been characterized using SEM and EDX. SEM examination of the concrete samples with Nano (0.3 SiO2+0.4 MgO) % by weight of cement shows a dense microstructure with no pores and the formation of Calcium Silicate Hydrate (CSH). Microcapsules containing cement with Nano (0.3 SiO2 +0.4 MgO) % have been prepared using a fluidized bed coating process (Pelletization method). The microcapsules with (7, 10, and 13) % of the cement's weight are then added to the concrete. Compressive strength, water absorption, density, flexural strength, and splitting tensile strength tests have been performed to study concrete properties. According to the obtained results, microcapsules are used as a useful material in the self-healing cracking process. They also improve concrete compressive strength, water absorption, density, flexural strength, and splitting tensile strength. 10% weight is selected as the best addition that enhances the characteristics that may be used in construction. These improvements are due to the high surface energy of the Nano (SiO2 + MgO) particles and the promotion of the degree of conversion of Calcium hydrate (CH) to Calcium Silicate Hydrate (CSH) gel, which fills the pores in the concrete matrix therefore a denser concrete was being achieved. The results have demonstrated that the microcapsules successfully survive mixing with cement and rupture successfully upon crack formation releasing the encapsulated nanomaterials.
  • Kapalı Erişim
    Yayın
    Investigation about the optimum alternative of polypropylene fibers in conventional concrete
    (Taylor's University Sdn Bhd, 2022) Mahdi, Zainab H.; Kadhum, Mohammed M.; Abdulghani, Mays R.; Abdulghani, Ghaith R.; Hwaiai, Duhuha A.
    This study was performing to find out the optimal alternative to expensive polypropylene fibers. This alternative was chicken's keratin-fibers, which were treated with chromium trioxide to eliminate the living materials. Several mixtures were ready using a mixing ratio of 1:1.5:3 (cement: sand: gravel) with keratin or polypropylene fibers, water, and a superplasticizer. Compressive strength, electrical resistance, and ultrasonic pulse velocity were tested by using cubic samples. The load-deflection relation was also tested by testing the reinforced concrete beam sample. The specimens that contain 1% of keratin-fibers showed enhancement in compressive strength, the percentage of increase of about (18.47, and 12.50)% compared with the reference sample and 1% polypropylene sample, respectively at the age of twenty-eight days. The electrical resistance of samples containing 1% and 2% of keratin-fibers was slightly less than the samples containing 1% and 2% polypropylene-fibers. The ultimate-flexural-load for beams that strengthened with 1% of keratin-fibers gave higher values (19.20 kN) than samples of (1 and 2)% polypropylene (17.30 and 17.10) kN and 2%keratin-fibers (18.98 kN) also, while the percentage of 2% keratin- fibers gave ultimate at deflection higher (0.337 mm) than the samples of (1 and 2) % polypropylene and 1 % keratin-fibers samples.