The Role of Kapok Fiber in Modifying the Strength and Thermal Properties of Cement and Silica Fume Mortars: An Experimental Approach

Utilization of natural fibers into cementitious mixtures is gaining attention for their recyclability, renewability, sustainable features and other environmental benefits. Among varied natural fibers, kapok fiber (KP), a kind of lightweight and renewable natural fiber deserves attention for its ability to improve the strength and thermal insulation features of sustainable mortars and application of KP fiber in cementitious mixtures is still very limited. This research examined the impact of KP fiber on the strength features, pore structure, thermal insulation performance, and microstructure of ordinary Portland cement (OPC) and silica fume (SF) mixtures. The results indicated that KP incorporation at a content of 1% by cement weight leads to insulation enhancement up to 19% with 9.50% flexural strength gain. A linear regression analysis was conducted between pore structure characteristics and the determined strength/conductivity values to reveal the impact of KP fibers in the cement matrix. KP fiber has considerable potential to play a role in structural cementitious material design as a sustainable material.