Summary table of SEM and EDX analysis.

This study investigates the flexural performance and microstructural evolution of reinforced concrete beams incorporating calcined montmorillonite (CMMT), metakaolin (MK), pyrolyzed coffee grounds (PCG), and hybrid fibers (steel or banana) as sustainable partial replacements for natural sand and cementitious binders. The replacement levels—12.5% SCM (CMMT or MK) and 15% PCG—were selected based on preliminary optimization trials and evidence from prior studies that identify these ranges as the threshold at which pozzolanic reactivity, workability, and particle packing achieve maximum benefit without compromising matrix integrity. Thirteen mix groups and a control beam were cast and tested under four-point bending, with three replicates per group. Statistical analysis using one-way ANOVA (α = 0.05) confirmed significant differences in peak load, stiffness, ductility, and energy absorption across mixes (p

本研究探讨了掺入煅烧蒙脱石（calcined montmorillonite, CMMT）、偏高岭土（metakaolin, MK）、热解咖啡渣（pyrolyzed coffee grounds, PCG）以及混杂纤维（钢纤维或香蕉纤维）的钢筋混凝土梁的抗弯性能与微观结构演变，上述材料可作为天然砂与胶凝材料的可持续性部分替代材料。本研究选定的替代参数为：12.5%的辅助胶凝材料（supplementary cementitious materials, SCM，CMMT或MK）与15%的PCG，该参数基于初步优化试验以及前期研究结论确定——现有研究表明，此范围可使火山灰活性、工作性与颗粒级配达到最优效益，同时不会损害基体完整性。共浇筑13个配合比组与1根对照梁，并开展四点弯曲试验，每组设置3个平行试样。采用单因素方差分析（one-way ANOVA, α=0.05）进行统计分析，结果证实不同配合比的试件在峰值荷载、刚度、延性与吸能能力方面存在显著差异（p