In the present study, the mechanical properties and the residual stress–strain behavior of lightweight concrete (LWC) containing pumice coarse aggregate and rock wool waste (consisting of mineral fibers) were explored prior to and following thermal loading. Key variables included the volume percentage of rock wool waste (0%, 2.5%, 5%, 7.5%, and 10%) and exposure temperature (20°C, 200°C, 400°C, and 600°C). Here, parameters playing a role in the compressive performance of LWC containing rock wool waste were examined. These parameters included the elastic modulus, compressive strength, strain at peak stress, ultimate strain, toughness index, stress–strain relationship, and failure mode. Then, several empirical relationships were proposed to predict different mechanical characteristics in terms of temperature and volume percentage of rock wool. Furthermore, the compressive strength, elastic modulus, and strain at peak stress values were compared to the prediction results of the ACI 216, EN 1994-1-2, ASCE, and CEB-FIP 1990 codes. The results demonstrated that the mechanical properties of the LWC specimens were degraded with temperature. The highest degradation in the temperature range under study occurred at 600°C, with around 50% and 80% drop in the compressive strength and elastic modulus, respectively. Furthermore, after exposure to 600°C, an increase of 2 to 2.8 folds occurred in the strain at peak stress and an increase of 2.6 to 3.4 folds occurred in the ultimate strain of the specimens relative to those at the ambient temperature. In the end, two stress–strain models were presented to capture the compressive performance of LWC including rock wool waste after elevated temperature exposure based on the empirical equations obtained for the mechanical characteristics. These models showed a relatively good correlation with the experimental data.

中文翻译：

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岩棉废料对高温暴露后浮石轻骨料混凝土压缩行为的影响

在本研究中，在热载荷之前和之后探索了含有浮石粗骨料和岩棉废料（由矿物纤维组成）的轻质混凝土 (LWC) 的机械性能和残余应力应变行为。关键变量包括岩棉废料的体积百分比（0%、2.5%、5%、7.5% 和 10%）和暴露温度（20°C、200°C、400°C 和 600°C）。在这里，检查了在含有岩棉废料的 LWC 的压缩性能中起作用的参数。这些参数包括弹性模量、压缩强度、峰值应力应变、极限应变、韧性指数、应力-应变关系和失效模式。然后，提出了几种经验关系来预测岩棉在温度和体积百分比方面的不同力学特性。此外，将峰值应力值下的压缩强度、弹性模量和应变与 ACI 216、EN 1994-1-2、ASCE 和 CEB-FIP 1990 规范的预测结果进行了比较。结果表明，LWC 试样的力学性能随温度的升高而降低。在所研究的温度范围内，最大降解发生在 600°C，压缩强度和弹性模量分别下降约 50% 和 80%。此外，暴露于 600°C 后，试样的峰值应力应变增加了 2 至 2.8 倍，而试样的极限应变相对于环境温度下的应变增加了 2.6 至 3.4 倍。到底，基于获得的机械特性经验方程，提出了两种应力-应变模型来捕捉包括岩棉废料在内的 LWC 在高温暴露后的压缩性能。这些模型与实验数据显示出较好的相关性。