The Study of Shrinkage of Polypropylene Fibers Reinforced Concrete

The problem of cracks in concrete is always found, and it leads to a reduction in the durability of reinforced concrete because the steel rebar in concrete can corrode. The use of fibers in concrete helps to enhance its tensile strength and it could control the quantity of cracks. The objectives of this research were: (a) to study the control of cracks caused by the plastic shrinkage of concrete; (b) to study the effects of the use of polypropylene fibers in concrete on total shrinkage of concrete. The study was divided into two parts. The first part focused on controlling cracks caused by plastic shrinkage of concrete reinforced polypropylene fibers. The fibers were added in concrete by varying the fiber content of 0.05, 0.10, 0.15, 0.20, and 0.25 percent by volume of concrete. This test was performed in a controlled laboratory for both temperature and relative humidity. The second part examines the effect of using polypropylene fibers on the total shrinkage of concrete according to ASTM C157 standard. The fiber contents were used at 0.10, 0.25, 0.50, and 1.00 percent by volume of concrete. It was found that the increase of polypropylene fibers can effectively reduce cracks caused by plastic shrinkage of concrete. In addition, the polypropylene fibers was added in concrete by varying the fiber content of 0.10 0.25 แ ล ะ 0.50 percent by volume of concrete which could reduce total shrinkage of concrete at an age of 120 days by 30, 18 and 4 percent, respectively. However, the use of polypropylene fibers content of 1.0 percent by volume led to an increase in the total shrinkage of concrete at an age of 120 days by 7 percent compared to the control sample.