Lightweight expanded-clay fiber concrete with improved characteristics reinforced with short natural fibers

Weight reduction should be accompanied by maintaining the strength and quality of materials utilized in construction. One of the comprehensive solutions to this problem can be the utilization of dispersed fiber reinforcement of concrete with plant fibers of various origins, which led to the sustainable production of concrete. Knowledge regarding the behavior of lightweight concrete with plant fibers is currently rather limited. Therefore, the primary aim of this article was to study the possibility of creating lightweight expanded-clay fiber concrete (ECFC) with improved characteristics, considering the dispersed reinforcement of this concrete with coconut (CF) and sisal (SF) fibers. Test methods and scanning electron microscopy (SEM) analyses were used for the structural study. Dispersed reinforcement of lightweight expanded clay concrete with fibers of organic origin has a positive effect on its mechanical characteristics. The optimal content of expanded clay in lightweight concrete was obtained in terms of the ratio of strength and density. The content of CF and SF, which provides the highest increases in compressive and flexural strength, was 2% of the mass of cement. It was found that SF in lightweight ECFC performs better and provides greater strength gains than CF. The compressive strength of ECFC with CF increased by 8.9%, the bending strength by 16.1%, and with SF by 10.1% and 18.3%, respectively, compared to the fiber-free composite. The coefficient of the constructive quality values of lightweight ECFC is up to 16% higher with CF and up to 18% with SF than a concrete composite without fibers. Moreover, formulas were derived to predict the compressive of ECFC with and without CF and SF.