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Towards sustainable construction: Harnessing potential of pumice powder for eco-friendly concrete, augmented by hybrid fiber integration to elevate concrete performance
(2024-12-01)
Farooq, Umar
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Rizwan, Muhammad
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Khaliq, Wasim
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Ejaz, Ali
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Saingam, Panumas
This study investigates the innovative use of industrial waste pozzolana, specifically pumice powder (PP), as a partial replacement for cement, combined with hybrid fibers in concrete. Seven formulations varying PP content from 10 % to 35 % were tested, identifying 15 % PP as optimal. PP improved porosity due to its fineness, leading to better homogeneity, a refined microstructure, and an optimum compressive strength of 28.8 MPa with reduced permeability, enhancing durability. Hybrid fibers, including steel fibers (SF) from waste tires and polypropylene fibers (PF), improved toughness, ductility, and resistance to brittle failure. Tests on hybrid fiber-reinforced concrete (HyFRC) mixes with 1 % and 2 % hybrid fibers showed up to an 18.09 % increase in compressive, tensile, and flexural strengths. Energy dissipation in compressive response improved by 544.20 %, while flexural and splitting responses increased by up to 299.65 % and 208.57 %. Durability assessments in hydrochloric (HCl) and sulfuric acid (H<inf>2</inf>SO<inf>4</inf>) exposure revealed the synergy of fibers and PP enhanced resistance to chemical degradation, with high PF mixes losing as little as 0.04 % strength. Scanning electron microscopy (SEM) confirmed a dense, well-bonded matrix with reduced porosity. Analytical characterizations of mixtures such as energy dispersive x-ray spectroscopy (EDX) were studied. Regression models developed using Popovic's and Mander's models, accurately predicted HyFRC stress-strain behavior, closely aligning with experimental results. The integration of PP and hybrid fibers not only improved mechanical properties but also extended service life in harsh environments, offering a cost-effective, sustainable concrete solution.
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Influence of natural fiber rope wrapping techniques on the compressive response of recycled aggregate concrete circular columns
(2023-09-01)
Chaiyasarn, Krisada
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Poovarodom, Nakhorn
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Ejaz, Ali
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Ng, Anne W.M.
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Hussain, Qudeer
The utilization of recycled waste in the production of new concrete raises significant concerns regarding the quality of the resulting concrete. One prominent drawback of recycled aggregate concrete (RAC) is its inferior mechanical properties compared to natural aggregate concrete. In this study, we examine the impact of hemp fiber rope (HFR) confinement on improving the compressive stress-strain behavior of RAC, specifically using recycled brick aggregates from fired-clay solid bricks (RAC-FCSB) as a partial substitute for natural coarse aggregates. Furthermore, we explore and compare the effectiveness of HFR confinement in the form of strips versus fully wrapped confinement. To conduct the experiments, a comprehensive framework was developed, involving a total of 32 cylindrical specimens. The parameters of interest included the configuration of HFR confinement (strips or full wrapping), the number of HFR layers, and the inherent strength of the concrete. The results indicate that HFR strips can significantly enhance the compressive stress-strain response. However, their performance falls short when compared to the fully wrapped HFR confinement. Nonetheless, HFR strips were able to enhance the peak compressive stress and strain of RAC-FCSB up to 204% and 190%, respectively. The second part of the study investigated the performance of existing models of HFR confinement in predicting the peak compressive stress and strain of RAC-FCSB. The deficiencies in existing models were highlighted, and new models based on non-linear regression analysis were proposed to accurately predict the peak compressive stress and strain of HFR-confined RAC-FCSB.
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Development of stress-strain models for concrete columns externally strengthened with steel clamps
(2023-05-09)
Yooprasertchai, Ekkachai
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Ejaz, Ali
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Saingam, Panumas
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Ng, Anne Wai Man
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Joyklad, Panuwat
A robust and sustainable solution is required to tackle the ever-growing generation of construction waste worldwide. It has been known that construction waste yields concrete with substandard mechanical properties when used as a replacement for natural aggregates. With attributes like easy application and low cost, this study investigated the performance of low cost and easily available steel clamps to improve the compressive stress–strain properties of concrete fabricated with recycled concrete and brick aggregates. Results demonstrate that steel clamps effectively improved the stress–strain behavior of recycled aggregate concrete, and this improvement was more pronounced in concrete with a higher percentage of recycled aggregates. Steel clamps confinement increased the compressive strength by up to 242% and 252% for recycled concrete and recycled brick aggregate concrete, respectively, whereas the corresponding strain was increased by up to 448% and 414%, respectively. The stress–strain response of steel clamp-confined RAC was idealized into two branches: the first branch was assumed to be parabolic in shape till the peak strength, and a linear degrading branch was assumed for the post-peak region. Separate equations were proposed using regression analysis for peak strength, strain, initial modulus, and post-peak degradation modulus. The complete stress–strain curves of steel clamp-confined RAC were generated by utilizing existing equations. The proposed regression equations were combined with existing equations to generate complete stress–strain curves of steel clamp-confined RAC. In general, good agreement between experimental and predicted stress–strain curves was obtained.

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