Effect of Treated Straw Fibers on the Mechanical and Durability Characteristics of Concrete

Abstract

gricultural waste such as rice and wheat straw can be used in the construction. Due to the high tensile strength and low weight, the practical application of these plant fibers has received increased attention from academic and industry especially in civil engineering, automotive and packaging industries. Natural fibers absorb water in concrete, due to which strength reduces. Like fibers, straw also provide ductility in concrete as well as affect the fresh and hardened properties and durability of concrete. Thus, this report deals with the study of different treatment of straw fibers and their effects on the mechanical and durability properties of concrete. This research work presents an investigation of mechanical properties (compressive strength, flexural strength and split tensile strength) and durability properties (shrinkage test, water absorption test and initial surface absorption test) of treated straw reinforced concrete. In this work, various treatment methods of rice straw such as soaking of straws in water, polymer treatment, hot water treatment (HWT) of straw and NaOH treatment of straws were accepted before mixed in concrete. The mix of M30 grade with seven sets of concrete mix was produced such as, control mix, dry straw concrete mix, wetted straw concrete mix, HWT of straw with 10% substitution of cement with silica fume, HWT of straw by substituting 20% of cement with metakaolin and NaOH treated straw concrete. All these concrete mix were casted as per specifications of IS code. The test results revealed best method for treatment of straws is hot water treatment and to enhance the compressive, flexural and bond strength, 20% cement should be replaced with metakaolin. Hot water treatment (HWT) of straw by swapping 20% of cement with metakaolin (H-W-MK) gives the most effective result in both 7 days and 28 days in case of compressive test. HWT of straw with inclusion of 20% MK and 10% SF in place of cement shows highest flexural strength. Maximum split tensile strength was also obtained by H-W-MK of straw mix concrete. Presence of rice straw fiber (RSF) shows great improvement in durability properties of concrete.