| Summary: | Abstract This study investigates the effects of incorporating chemically treated Palm Tree Fronds (PTF) microfiber as a partial sand replacement in concrete. Concrete grades C28, C35, and C40 were evaluated with varying PTF contents ranging from 0 to 4% of sand volume. A total of 571 samples were tested using destructive and non-destructive methods to evaluate structural integrity and performance. The results revealed that PTF addition significantly enhanced workability across all grades, with higher PTF content improving slump values due to fiber-induced changes in rheological properties. Density decreased consistently, with reductions at 28 days ranging from 0.9 to 3.7% across grades, stabilizing at lower levels in higher-grade concrete. Compressive strength exhibited a linear decline with increasing PTF content, with reductions at 28 days ranging from 14.5 to 43.6% across grades, and tensile strength followed a similar trend, decreasing by 21.3% to 35.6%. Water absorption increased substantially, with an average rise from 10.6% at 1% PTF content to 51.2% at 4%, reflecting increased porosity. Thermal conductivity progressively decreased, with reductions averaging 26% to 33.6%, demonstrating enhanced insulating properties. Non-destructive tests indicated significant reductions in UPV and rebound numbers, correlating with increased fiber content and reduced matrix uniformity. SEM analysis revealed that PTF microfibers introduced porosity and microstructural discontinuities, contributing to the observed reductions in mechanical properties and increased permeability. Optimization analysis identified the optimal PTF content for balancing mechanical and thermal performance as below 1% for C28 and between 2.3% and 2.5% for higher grades. Consideration of a hybrid fiber mix, incorporating synthetic fibers such as steel, glass, or polypropylene, is recommended to compensate for the strength reduction associated with PTF addition. These findings demonstrate the potential of PTF-reinforced concrete for sustainable and energy-efficient construction, particularly in semi-structural applications.
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