Effect of increased volume of fibers on the fracture properties of cementitious composites

Altürk, Ufuk Emre
To apply fiber as a reinforcement, which is much older than the history of concrete, together with concrete is rather a new technology, while cement based products are the most consumed materials after water, considering the consumption amounts. The application areas of fiber reinforced concrete are growing day by day. However, in common practice, fiber content is usually limited up to 2% due to economical, workability and agglomeration problems. This study investigates the changes in the performance of nine FRC mixes built with three different types of fibers; steel, polypropylene and polypropylene-polyethylene copolymer, with three different dosages; 2%, 4% and 6% per volume. With the help of fly ash and concrete chemicals, the properties of the matrix can be regulated to breach the limit amount of fibers, provided to act as single body. To measure the increase in the flexural capacity and energy absorption rates, and also any effects on the compressive strength, three different test set-ups were prepared, cube compression, beam bending and tensile splitting tests. For data acquisition, video extensometer cameras are used. By the help of this high-frequency gadgets, each phase of fraction was recorded in detail. Energy absorption capacities were derived through calculations with load and deflection data. To assure objective comparison, calculated energy values were used in the comparative study.