The use of raw sugarcane bagasse ash (SCBA) as sand replacement in the production of engineered cementitious composites (ECCs) can improve its cost-effectiveness and practicality. A recent study by the authors showed that the use of raw SCBA as a replacement to sand in ECC mixtures substantially enhances the tensile ductility and provides mild improvements in tensile strength; however, it also indicated a need to further elucidate the mechanisms producing such improvements. Therefore, the present study examined the effects of raw SCBA as a sand replacement in ECC’s fundamental fiber-bridging relationship, $\sigma \left(\delta \right)$, through single crack tensile test (SCTT) using 1% polyvinyl alcohol (PVA) fiber volume fraction. The PVA fiber volume fraction was reduced from 1.5% in the previous study to 1% in this study to ensure that a single crack was produced, which is a necessary condition to obtain the fundamental $\sigma \left(\delta \right)$ relationship. A total of five mixtures were evaluated at different replacement levels of sand with raw SCBA (i.e., 0%, 25%, 50%, 75%, and 100%). SCTT results revealed that raw SCBA produced minor effects on the fiber-bridging capacity but significantly increased the complementary energy ( $J_b^{\prime }$). A positive correlation was observed between the pseudo strain-hardening (PSH) strength index and raw SCBA content. Since the PSH strength index was higher than the recommended value (i.e., 1.3) for robust PSH behavior, it was concluded that the main factor contributing to tensile ductility enhancements was the increase in the PSH energy index resulting from the notable increase of $J_b^{\prime }$ and potential decrease in matrix fracture toughness.

在工程水泥基复合材料 (ECC) 的生产中使用甘蔗渣原灰 (SCBA) 作为砂替代品可以提高其成本效益和实用性。作者最近的一项研究表明，在 ECC 混合物中使用原始 SCBA 作为沙子的替代品可显着提高拉伸延展性并略微提高拉伸强度；然而，它还表明需要进一步阐明产生这种改进的机制。因此，本研究检查了原始 SCBA 作为砂替代物在 ECC 基本纤维桥接关系中的影响，$\sigma \left(\delta \right)$, 通过使用 1% 聚乙烯醇 (PVA) 纤维体积分数的单裂纹拉伸试验 (SCTT)。将 PVA 纤维体积分数从之前研究中的 1.5% 降低到本研究中的 1%，以确保产生单个裂纹，这是获得基本结构的必要条件。$\sigma \left(\delta \right)$关系。在用原始 SCBA（即 0%、25%、50%、75% 和 100%）替换沙子的不同水平下，对总共五种混合物进行了评估。SCTT 结果表明，原始 SCBA 对纤维桥接能力的影响很小，但显着增加了补充能量。$J_{乙}^{\prime }$）。在假应变硬化 (PSH) 强度指数和原始 SCBA 含量之间观察到正相关。由于 PSH 强度指数高于稳健 PSH 行为的推荐值（即 1.3），因此得出结论，导致拉伸延展性增强的主要因素是 PSH 能量指数的增加，这是由于$J_{乙}^{\prime }$ 和基体断裂韧性的潜在降低。