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(searched for: doi:10.1680/jmacr.19.00485)
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Published: 25 February 2021
by MDPI
Applied Sciences, Volume 11; https://doi.org/10.3390/app11052053

Abstract:
Since between 1.5 and 8 kg (400 kg/patient/year) of biomedical polymeric waste (BPW) is usually discarded by landfilling or combusting after each dialysis treatment, this study provides evidence for safe and environment-friendly utilisation of BPW, sourced from dialysis treatment and donated by the health and industrial partners, by incorporating it in high-strength concrete. Moreover, the paper aims to provide engineers, designers, and the construction industry with information regarding the mechanical performance of high-strength concrete containing BPW, and the susceptibility of the current international codes and standards on the prediction of the mechanical performance. A new concrete mix design incorporating BPW was proposed and verified by several trial mixes. Three Soft, Hard, and Hybrid BPW were added to the conventional high-strength concrete in different percentages ranging from 1.5% to 9% by weight of cement. Afterwards, the fresh and hardened concrete properties, namely slump, density, compressive strength, tensile strength, modulus of elasticity, and Scanning Electron Microscopy (SEM), were investigated, and existing prediction models were employed to verify their suitability for the new concrete. Generally, adding Hybrid BPW resulted in better mechanical performance than soft or hard BPW addition, while eliminating the waste separation phase. The results also showed that the mechanical performance of BPW-containing concrete is predictable by current codes, addressing possible engineering design limitations. New higher accuracy regression-based models were also proposed to reach better engineering interpretations.
Published: 23 July 2020
by MDPI
Materials, Volume 13; https://doi.org/10.3390/ma13153262

Abstract:
This paper investigates a potential application of hard-to-recycle plastic waste as polymeric addition in high strength concrete, with a focus on the potential to mitigate heat-induced concrete spalling and the consequent effects on the mechanical properties. The waste corresponds to soft and hard plastic, including household polymers vastly disposed of in landfills, although technically recyclable. Mechanical and physical properties, cracking, mass loss, and the occurrence of spalling were assessed in high strength concrete samples produced with either plastic waste or polypropylene fibers after 2-h exposure to 600 °C. The analysis was supported by Scanning Electron Microscopy and X-Ray Computed Tomography images. The plastic waste is composed of different polymers with a thermal degradation between 250 to 500 °C. Polypropylene (PP) fibers and plastic waste dispersed in concrete have proved to play an essential role in mitigating heat-induced concrete spalling, contributing to the release of internal pressure after the polymer melting. The different morphology of plastic waste and polypropylene fibers leads to distinct mechanisms of action. While the vapor pressure dissipation network originated by polypropylene fibers is related to the formation of continuous channels, the plastic waste seems to cause discontinuous reservoirs and fewer damages into the concrete matrix. The incorporation of plastic waste improved heat-induced concrete spalling performance. While 6 kg/m3 of plastic increased the mechanical performance after exposure to high temperature, the incorporation of 3 kg/m3 resulted in mechanical properties comparable to the reference concrete.
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