Effects of Micro Cellulose Fibers Addition on Concrete Mechanical Properties Under Flexure and Uniaxial Tension

Abstract

Natural fiber reinforced concrete (NFRC) has been brought into the lime light again by researchers to address the issues of sustainability, recyclability, and CO2 gas emission that are associated with the manufacturing and usage of construction materials. As fibers are one of the main ingredients of NFRC, understanding their effect on the mechanical properties of the concrete requires much attention to provide users a confidence to use more sustainable materials in construction.

In this study, processed virgin micro cellulose fibers extracted from pine trees were added in 32 MPa concrete in two different volume fractions i.e. 0.25% and 0.5%. As compressive strength and tensile strength are important design parameters that need to be accounted for in structural design applications, these strengths were evaluated using applicable ASTM standards after 28 days of wet curing. Owing to inherent difficulties in testing concrete under direct tension, the flexural test was employed to determine the tensile properties through inverse analysis of the concrete under consideration. An effort was also made to test the equivalent strength mortar in direct tension and report the difference in tensile properties generated from the indirect test (flexural) and the direct uniaxial tension test. It was observed that the addition of 0.25% fiber Vf in concrete caused the most increase in peak load which was followed by 0.5% fiber Vf. The decrease in peak load capacity with an increase in fiber volume fraction was attributed to the poor dense structure that resulted because of fiber mixing issues in concrete.