Abstract
The addition of natural fibers used as reinforcement has great appeal in the construction materials industry since natural fibers are cheaper, biodegradable, and easily available. In this work, we analyzed the feasibility of using the fibers of piassava, tucum palm, razor grass, and jute from the Amazon rainforest as reinforcement in mortars, exploiting the mechanical properties of compressive and flexural strength of samples with 1.5%, 3.0%, and 4.5% mass addition of the composite binder (50% Portland cement + 40% metakaolin + 10% fly ash). The mortars were reinforced with untreated (natural) and treated (hot water treatment, hornification, 8% NaOH solution, and hybridization) fibers, submitted to two types of curing (submerged in water, and inflated with CO2 in a pressurized autoclave) for 28 days. Mortars without fibers were used as a reference. For the durability study, the samples were submitted to 20 drying/wetting cycles. The fibers improved the flexural strength of the mortars and prevented the abrupt rupture of the samples, in contrast to the fragile behavior of the reference samples. The autoclave cure increased the compressive strength of the piassava and tucum palm samples with 4.5% of fibers.
Highlights
Vegetable fibers have been used to reinforce building materials since the beginning of human civilization, for the construction of tents and walls
The chemical treatments removed dirt and part of the lignin impregnated in the fibrils, causing greater water absorption by the fibers, since it exposed OH groups belonging to cellulose
The increase in the amount of cellulose improves the mechanical strength of the fiber
Summary
Vegetable fibers have been used to reinforce building materials since the beginning of human civilization, for the construction of tents and walls. Vegetable fibers, mixed with earth and cementitious materials, were used to improve the mechanical strength of these materials; this use was determined empirically [1,2]. The production of basalt and glass fibers are similar. Crushed basalt rock is the only raw material required for manufacturing the first one and glass fibers is produced from various components. Basalt fibers were only developed in recent decades and require less energy to be produced. Their strength and modulus properties are situated among those offered by glass fibers. Current research shows that the structural behavior, including long-term deflections due to creep and cyclical loading, is like glass fiber, internationally recognized code authorities have yet to acknowledge basalt in their codes
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