Effect of diatomaceous earth on properties of glass fiber reinforced mortar

Abstract The durability of glass fiber reinforced mortar (GFRM) is often compromised by the highly alkaline environment of the cement matrix, which leads to fiber corrosion and degradation of mechanical performance. To address this issue, this study proposes a novel and sustainable approach by incorporating diatomaceous earth (DE), a natural pozzolanic material rich in amorphous silica, to regulate matrix alkalinity and enhance the microstructural integrity of GFRM. Unlike conventional mineral replacements, DE actively participates in hydration reactions, consuming CH and generating additional C‐S‐H gel, which not only reduces the alkalinity but also promotes microstructural densification and optimization of the ITZ between fibers and matrix. Experimental investigations were conducted to evaluate the effects of varying DE dosages (0–16 wt%) on the fresh properties, mechanical strength, shrinkage behavior, and durability of GFRM. The results revealed that DE effectively mitigated GF corrosion, refined the pore structure, and significantly enhanced both mechanical and durability performance. At an optimal dosage of 8 wt%, the 90‐day flexural and compressive strengths increased by 17.8% and 15.5%, respectively, while the 28‐day drying shrinkage decreased by 15.3%. This study provides new insights into the design of durable and eco‐efficient fiber‐reinforced composites through DE‐induced alkalinity regulation, microstructural densification, and ITZ optimization.