Utilization of recycled fibers in concrete

In response to rapid accumulation of industrial and domestic wastes worldwide, and to rapid reduction of available landfills due to growing environmental concern, it is vital to find a new outlet for waste disposal. In this paper, we investigate application of various recycled fibers from used tires and carpets in concrete. These recycled fibers include polyester, nylon, polypropylene, and steel. In the current study, emphasis is placed on dry shrinkage response of concrete reinforced with various recycled fibers. Shrinkage cracking is one of the major causes of deterioration for concrete flatwork construction such as pavement and parking slab. Comparisons are also made with reinforcement of virgin steel and polypropylene fibers which are commonly employed in practice for shrinkage crack control. Free shrinkage as well as restrained shrinkage using a ring-type specimens is measured. In the latter case, cracking phenomenon and crack width are continuously monitored with the aid of a microscope. Some of the recycled fibers are found to be as effective as virgin fibers in suppressing shrinkage cracks. This finding is particularly important since the use of recycled fibers in concrete is not only to consume otherwise wastes but also to provide value-added products to the construction industry.