Utilization of hybrid fibers in different types of concrete and their activity

Abstract In this work, the influence of using hybrid fibers on the mechanical properties of two types of concrete: high-strength concrete (HSC) and lightweight concrete (LWC) was studied. Using hybrid fibers instead of using only one type reduced the negative effect on concrete mechanical performance. The glass fiber (GF) and polypropylene fiber (PPF) were used in different contents ranged from 0.2 to 1% as weight % of binder content. Moreover, combinations of both fibers “GF + PPF” were used in contents % of “0.3 + 0.5%,” “0.5 + 0.5%,” “0.3 + 1%,” and “0.5 + 1%.” LWC mixes were prepared by replacing 40% of the coarse aggregate of reference mix with volcanic material (pumice) as a volumetric replacing. To produce HSC, the water-to-cement ratio was reduced to 0.3, 10% silica fume was added, and 1% super plasticizer was used to obtain the consistency. Compressive strength, splitting strength, and flexural strength tests were carried out. The results showed that using 0.7% GF displayed the highest increases in compressive, splitting tensile, and flexural strength of HSC and LWC mixes. Furthermore, GF exhibited better performance and higher values in compressive, splitting tensile, and flexural strength tests in comparison with PPF. The optimum hybrid fiber content displaying the highest increment of all tested properties in both concrete types, HSC and LWC, was “0.5% GF + 0.5% PPF.”