To promote the sustainable development of the ecological environment, facilitate the recycling of recycled concrete and explore efficient approaches to enhance the performance of structural components, this study proposes a post-tensioned precast beam model manufactured with basalt-fiber-reinforced recycled concrete–conventional concrete. Flexural performance tests were conducted on 12 beams with different concrete strength grades (C40, C50, C60), basalt-fiber-reinforced recycled concrete layer thicknesses (200 mm, 250 mm, 300 mm), and basalt fiber volume fractions (0%, 0.1%, 0.2%). The results show that the incorporation of basalt fiber can effectively inhibit crack development, and improve the stiffness and flexural strength of components. Through theoretical analysis, the factors affecting the ultimate stress formula for high-strength prestressing steel strands are attributed to the comprehensive reinforcement index and prestressed reinforcement index, thereby obtaining a flexural strength formula. Coefficients describing the influences of basalt fiber and recycled coarse aggregate were introduced and combined with average crack spacing and width measurements to derive a post-tensioned precast beam model of average crack spacing and width. Based on the derived calculation model, the average deviation between the tested and calculated results of the ultimate bending moment is less than 6%, and the average deviation between the tested and calculated results of the average crack width is less than 9%. The proposed model has good prediction accuracy for evaluating the flexural strength and average crack width, which provides a theoretical basis for assessing the flexural performance of composite beams.

中文翻译：

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用玄武岩纤维增强再生混凝土-传统混凝土制造的后张预制梁的弯曲性能

为了促进生态环境的可持续发展，促进再生混凝土的回收利用，探索提高结构构件性能的有效方法，本研究提出了一种用玄武岩纤维增强再生混凝土-常规混凝土制造的后张预制梁模型。对不同混凝土强度等级（C40、C50、C60）、玄武岩纤维再生混凝土层厚（200 mm、250 mm、300 mm）、玄武岩纤维体积分数（0%、 0.1%、0.2%）。结果表明，玄武岩纤维的掺入可以有效抑制裂纹的发展，提高构件的刚度和弯曲强度。通过理论分析，将影响高强预应力钢绞线极限应力公式的因素归结为综合配筋指数和预应力配筋指数，从而得到抗弯强度公式。引入描述玄武岩纤维和再生粗骨料影响的系数，并与平均裂缝间距和宽度测量相结合，得出平均裂缝间距和宽度的后张预制梁模型。基于推导的计算模型，极限弯矩实测与计算结果平均偏差小于6%，平均裂缝宽度实测与计算结果平均偏差小于9%。该模型对评估组合梁的抗弯强度和平均裂缝宽度具有良好的预测精度，为评估组合梁的抗弯性能提供了理论依据。