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Start date: 2023Subject: search.filters.subject.Hemp confinement

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    Temperature-resilient performance of hemp rope–Confined recycled aggregate concrete in axial compression
    (2026-07-01)
    Thansirichaisree, Phromphat
    ;
    Ejaz, Ali
    ;
    Chaimahawan, Preeda
    ;
    Hussain, Qudeer
    ;
    Jirasakjamroonsri, Amornthep
    This study addresses the growing need for sustainable and cost-effective alternatives to conventional fiber-reinforced polymer (FRP) confinement systems, particularly for recycled aggregate concrete (RAC) subjected to elevated temperatures. The axial compressive behavior of hemp rope-confined RAC cylinders was experimentally investigated under ambient and moderate thermal exposure (150°C). Two strength grades were considered, with confinement applied using one to three layers of hemp rope. The results demonstrate that hemp confinement significantly enhances both compressive strength and axial strain, with improvements increasing with the number of layers, while strain enhancement was consistently more pronounced than strength gain. The stress–strain response exhibited a characteristic two-stage behavior, consisting of an initial unconfined-like region followed by a confinement-activated ascending branch. The elastic modulus of RAC was found to be approximately 21.9% to 29.7% lower than ACI 318-19 predictions, suggesting a reduction factor of about 25% for practical applications. Thermal exposure had a limited effect on normalized strength and strain parameters, although post-peak stiffness showed some sensitivity. Notably, confinement proved even more effective in thermally damaged specimens due to increased lateral deformability. A regression-based analytical model was developed to predict the complete stress–strain response, showing close agreement with experimental results. This study is among the first to evaluate the performance of hemp rope confinement for RAC under elevated temperature conditions and to propose a unified predictive framework. Overall, the findings confirm that hemp rope confinement is an effective, sustainable, and reliable technique for enhancing both the strength and ductility of RAC, with strong potential for structural applications, including post-fire rehabilitation.
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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
    ;
    Poovarodom, Nakhorn
    ;
    Ejaz, Ali
    ;
    Ng, Anne W.M.
    ;
    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.