Comparative study on shear strength and life cycle assessment of reinforced concrete beams containing different types of fibers

A variety of fibers currently exists in the construction market; however, their effect on concrete performance, cost, and environment are not being evaluated systematically. This study investigates the influence of different fibers (polypropylene, glass, basalt, polyvinyl alcohol, and steel), having different aspect ratios, on shear strength of reinforced concrete beams designed without stirrups. A life cycle assessment for each fiber type highlighting the environmental emissions and production costs is performed. Test results showed that the shear strength increased by 38.6% with the use of polypropylene fibers possessing low aspect ratio of 42, while such increase was limited to 11.5% with the incorporation of basalt fibers possessing an aspect ratio of 700. The polyvinyl alcohol fibers exhibited the highest ductility and energy transfer in the post-peak region, while the load versus deflection curves sharply dropped for concrete containing steel fibers reflecting reduced adhesion with the cement paste. The life cycle assessment showed higher environmental impact varying from 4 to 9% due to fibers additions, together with increased cost ranging between 34 to 150%. When taking all factors into account (performance, cost, and environmental impact), the polyvinyl alcohol fibers were most efficient followed by the polypropylene ones.