To deal with the rising environmental issues, more attention is now being given to recycled-aggregate concrete to partly meet the demands of the construction industry. However, recycled concrete is inferior in mechanical and durability performance compared to its counterpart natural-aggregate concrete. In this study, an effective approach is presented to improve the strength and durability performance of recycled concrete using supplementary materials, namely fly ash and hooked steel fiber. Low calcium refined fly ash was used at 0%, 15%, and 30% by mass replacement of cement with three different doses of steel fiber (0%, 0.5% and 1%). Mixes were evaluated based on results of several strength (compressive strength, splitting-tensile strength, and flexural strength) and durability tests (water absorption, acid attack resistance, and chloride-ion penetration). The results showed that incorporating both steel fiber and fly ash in recycled concrete significantly improves its mechanical performance and the proposed concrete can be markedly upgraded. The strength testing revealed that a synergistic effect of 15% fly ash and 1% steel fiber upgraded the flexural, splitting-tensile, and compressive strength of recycled concrete by 73–78%, 39–50%, and 13–23%, respectively. Fly ash minimized the negative effects of both recycled coarse aggregates and steel fiber incorporation on water and chloride-ion permeability resistance of concrete. Additionally, both fly ash and steel fiber were remarkably useful in increasing the acid attack resistance of concrete.

为了解决日益严重的环境问题，现在正更加重视再生骨料混凝土，以部分满足建筑业的需求。但是，再生混凝土与天然混凝土相比，其机械性能和耐久性性能均较差。在这项研究中，提出了一种有效的方法，可使用粉煤灰和带钩钢纤维作为补充材料来提高再生混凝土的强度和耐久性能。低钙精制粉煤灰以三种不同剂量的钢纤维（0％，0.5％和1％）替代水泥的质量百分比分别为0％，15％和30％。根据几种强度（抗压强度，抗拉强度和抗弯强度）和耐久性试验（吸水率，耐酸侵蚀性，和氯离子渗透）。结果表明，将钢纤维和粉煤灰混入再生混凝土中可显着改善其机械性能，并且可以显着改进建议的混凝土。强度测试表明，15％的粉煤灰和1％的钢纤维的协同作用使再生混凝土的抗折，抗拉强度和抗压强度分别提高了73％至78％，39％至50％和13％至23％。 。粉煤灰最大程度地减少了再生粗骨料和掺入钢纤维对混凝土耐水和氯离子渗透性的不利影响。另外，粉煤灰和钢纤维在提高混凝土的耐酸侵蚀性方面也非常有用。结果表明，将钢纤维和粉煤灰混入再生混凝土中可显着改善其机械性能，并且可以显着改进建议的混凝土。强度测试表明，15％的粉煤灰和1％的钢纤维的协同作用使再生混凝土的抗折强度，劈裂强度和抗压强度分别提高了73–78％，39–50％和13–23％ 。粉煤灰最大程度地减少了再生粗骨料和掺入钢纤维对混凝土耐水和氯离子渗透性的不利影响。另外，粉煤灰和钢纤维在提高混凝土的耐酸侵蚀性方面也非常有用。结果表明，将钢纤维和粉煤灰混入再生混凝土中可显着改善其机械性能，并且可以显着改进建议的混凝土。强度测试表明，15％的粉煤灰和1％的钢纤维的协同作用使再生混凝土的抗折强度，劈裂强度和抗压强度分别提高了73–78％，39–50％和13–23％ 。粉煤灰最大程度地减少了再生粗骨料和掺入钢纤维对混凝土耐水和氯离子渗透性的不利影响。另外，粉煤灰和钢纤维在提高混凝土的耐酸侵蚀性方面也非常有用。强度测试表明，15％的粉煤灰和1％的钢纤维的协同作用使再生混凝土的抗折强度，劈裂强度和抗压强度分别提高了73–78％，39–50％和13–23％ 。粉煤灰最大程度地减少了再生粗骨料和掺入钢纤维对混凝土耐水和氯离子渗透性的不利影响。另外，粉煤灰和钢纤维在提高混凝土的耐酸侵蚀性方面也非常有用。强度测试表明，15％的粉煤灰和1％的钢纤维的协同作用使再生混凝土的抗折强度，劈裂强度和抗压强度分别提高了73–78％，39–50％和13–23％ 。粉煤灰最大程度地减少了再生粗骨料和掺入钢纤维对混凝土耐水和氯离子渗透性的不利影响。另外，粉煤灰和钢纤维在提高混凝土的耐酸侵蚀性方面也非常有用。