Influence of fibers on drying shrinkage in restrained concrete

- Fibers do not have any considerable effect on compressive strength of the concretes.
- The drying shrinkage strength was highly dependent on fibers' modules of elasticity.
- The physical properties of fibers have direct effects on reducing the cracking width.
- The steel fibers showed the best performance due to their hook-shaped tail.
- Polypropylene fibers also showed better performance in preventing crack development.

Drying shrinkage cracks mainly start to develop at the exposed surface of the concrete elements due to the shrinkage strain caused by self-desiccation. For the purpose of controlling drying shrinkage cracks additions and fibers are used in fresh concretes in order to provide high early age mechanical capacity for moderating the crack development. The purpose of this study is to evaluate the performance of using different fibers in reducing the drying shrinkage and cracking under restrained conditions. To investigate the effectiveness of using both polymeric and metal fibers in concrete, three different types of fibers, including polypropylene fiber, polyolefin fibers, and steel fiber were used in this study. The maximum drying shrinkage strength was highly dependent on fibers' module of elasticity. The average length cracking and its pattern in fiber reinforced concretes were different than control concrete. The physical properties of fibers have direct effects on reducing the cracking width.