Effect of Using Different Fibers on Slab on Grades

Slab on grade, also called floors on ground, are different from other structural members. First, they are supported directly by soil, and their success or failure may depend more on the soil qualities than on the slab construction. Second, they carry equipment and floor finishes, and any defect in the slab s integrity or moisture resistance affects those elements. A floor slab undergoing drying shrinkage may not only crack, but also break the brittle ceramic tile it carries. Failure may also occur due to overloading. For reducing cracks propagation, control or contraction joints are used. In this research, 225 specimens by fifteen mix design with different dosage of polypropylene and steel fibers were prepared for evaluating compressive, impact and flexural testing at the ages of 7 and 28 days. As a result, optimum dosage of polypropylene fibers was 1.6 kg/m3 and at this dosage, impact resistance enhanced about 460% and flexural strength enhanced about 70% in comparison with control specimens. Steel fibers improved impact resistance and flexural strength about 312% and 58% respectively at the dosage of 30 kg/m3. Results also showed that compressive strengths of specimens are not significantly increased by using fibers.

Keywords:

slab on grade , Polypropylene Fibers , Steel Fibers , Cracking