Presently, significant attention is directed towards utilisation of recycled plastic waste as an environmentally sustainable substitute for natural aggregate in cementitious concrete materials. This is aimed to bolster the greening endeavours of local construction industry and address the pressing need to improve global plastic recycling rates. Despite extensive literature on different mechanisms underlying various fire responses and spalling behaviour of cementitious materials, it remains unclear if these propositions are applicable to the mechanisms behind the fire response of concrete materials incorporated with polymeric aggregate. Therefore, the key focus of this study is to examine the effect of recycled heterogeneous carbonaceous aggregate (RHCA), recovered from municipal solid waste streams, on fire performance of high strength concrete (HSC). A series of analytical and microscopic tests were carried out at 200, 400, 600 and 800 °C on six HSC mixes containing 0, 10, 20, 30, 40, and 50 % RHCA by volume of natural sand as replacement to address the knowledge gaps. The experimental data shows that incorporation of RHCA resulted in a higher mass loss and lower mechanical properties in residual state. It is revealed that thermal expansion of RHCA below its melting temperature was responsible for creation of interconnected crack network within the concrete system that has direct bearing on the residual physical and mechanical properties of the concrete specimens often subjected to fire conditions. Although explosive spalling is avoided under ISO 834 heating, thermochemical mechanisms based on radical reactions and the Bolland-Gee autoxidation scheme were applied to explain the occurrence of ignition at high RHCA content. Finally, fire load density of concrete mixes with varying amounts of RHCA is quantified and recommended for different occupancies under Eurocode 1 EN1991-1-2.

中文翻译：

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再生非均质碳质骨料对高强混凝土防火性能的影响


目前，人们非常重视利用回收的塑料废料作为水泥基混凝土材料中天然骨料的环境可持续替代品。此举旨在推动本地建筑业的绿化工作，并解决提高全球塑料回收率的迫切需求。尽管有大量文献介绍了各种火灾响应和胶凝材料剥落行为的不同机制，但目前尚不清楚这些主张是否适用于掺入聚合物骨料的混凝土材料的火灾响应机制。因此，本研究的重点是检查从城市固体废物流中回收的回收非均质碳质骨料 （RHCA） 对高强度混凝土 （HSC） 防火性能的影响。在 200、400、600 和 800 °C 下，对含有 0、10、20、30、40 和 50% RHCA 的六种 HSC 混合物进行了一系列分析和显微镜测试（按体积计）天然砂作为替代品，以解决知识差距。实验数据表明，掺入 RHCA 会导致残余状态下的质量损失较高且机械性能较低。结果表明，RHCA 低于其熔化温度的热膨胀是导致混凝土系统内产生相互连接的裂缝网络的原因，该裂缝网络直接影响经常受到火灾条件下的混凝土试样的残余物理和机械性能。尽管在 ISO 834 加热下避免了爆炸性剥落，但基于自由基反应的热化学机制和 Bolland-Gee 自氧化方案被应用于解释高 RHCA 含量下着火的发生。 最后，根据欧洲规范 1 EN1991-1-2，对不同 RHCA 含量的混凝土混合物的火灾荷载密度进行量化，并针对不同的占用情况提出建议。