Mechanical and thermal properties of structural lightweight bamboo fiber-reinforced insulating mortar

Abstract

This study investigated the use of local vegetal wastes, specifically bamboo fibers , to develop a new cementitious material with both insulating and load-bearing capabilities for construction. Bamboo fiber-reinforced mortar (BFRM) was evaluated for its microstructural, mechanical, and thermal properties. Key parameters, including fiber content, cement-to-sand (C/S) ratio, and aggregate type and size, were analyzed to optimize the formulation. Alkali-treated bamboo fibers were incorporated into the mortar at varying levels, from 30 % to 50 % by weight of cement. The results exhibited that increasing fiber content reduced the density and mechanical strength of cementitious matrix , while conversely improving its thermal insulation properties . An excessive addition of fibers could result in lower thermal conductivity , but would make the composite unsuitable for structural applications. In addition, variations in the C/S ratio affected both thermal and mechanical properties. The optimal mechanical strength was achieved at a C/S ratio of 1/2, as deviations from this ratio did not enhance strength. Furthermore, both silica and tuff-crushed sand were evaluated as fine aggregates. Finer aggregates improved the compactness, produced a denser and resistant matrix but resulted in an increase in the thermal conductivity . The experimental findings identified six formulations that successfully balanced mechanical and thermal insulation properties, classifying them as structural and insulating lightweight concrete. The lowest thermal conductivity recorded was 0.502 W/(m.K), representing a 70 % of reduction compared to the control mortar, while still remained within the minimum standards required for load-bearing strength. This approach offered a sustainable alternative for producing building materials by utilizing locally available vegetal wastes.

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