Expanded flyash clay aggregate (EFCA) is a promising sustainable alternative to coarse aggregate in concrete. Concrete specimens with conventional natural aggregate and EFCA as coarse aggregates were prepared separately and exposed to elevated temperatures of range 200°C, 400°C, 600°C and 800°C, observed for surface changes like change in color and formation of visual cracks, tested for loss in mass, strength and water absorption, analyzed by XRD for mineralogical changes through variation in chemical composition. Specimens when exposed up to 400°C has not shown any notable changes in the above property, beyond which strength of both specimens started to decrease gradually, at higher temperature EFCA mix showed loss in mass of 4.5% compared with normal concrete, visual observation of specimen surface showed EFCA specimens sustained cracks till 600°C. EFCA mix also showed a constant rate of water absorption. Concrete with EFCA showed consistently higher compressive strength at higher temperature up to 400°C and found satisfactory in all aspects tested made EFCA as coarse aggregate in concrete as a sustainable alternative to natural aggregates.

中文翻译：

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膨胀粉煤灰粘土骨料混凝土暴露于高温的行为

膨胀粉煤灰粘土骨料 (EFCA) 是混凝土中粗骨料的一种有前途的可持续替代品。单独制备具有常规天然骨料和 EFCA 作为粗骨料的混凝土试样，并暴露在 200°C、400°C、600°C 和 800°C 的高温下，观察表面变化，如颜色变化和视觉裂缝的形成，测试质量、强度和吸水率的损失，通过 XRD 分析通过化学成分变化的矿物学变化。暴露于 400°C 的试样在上述性能方面没有显示出任何显着变化，超过此之后，两个试样的强度开始逐渐下降，在较高温度下，EFCA 混合料与普通混凝土相比质量损失 4.5%，对试样表面的目视观察表明，EFCA 试样在 600°C 时仍会出现裂纹。EFCA 混合物还显示出恒定的吸水率。含有 EFCA 的混凝土在高达 400°C 的高温下始终表现出更高的抗压强度，并且在测试的所有方面都令人满意，这使得 EFCA 作为混凝土中的粗骨料作为天然骨料的可持续替代品。