ABSTRACT
This paper reports a laboratory investigation on the contribution of polypropylene fibers (15 mm long) to the reduction of crack widths and area caused by restrained plastic shrinkage of different self consolidating concrete (SCC) and self consolidating light concrete (SCLC) mixes during the first 24 h after casting. The polypropylene fiber (PF) fresh concrete to be tested was laid on top of a fully hardened and grooved based concrete that provided the bottom restraint and this resulted in cracking in freshly (PF) concrete placed overlay. Prismatic (PF) concrete specimens (1060 X 76.2 X 38.1 mm) freshly cast on top of a grooved and hardened concrete substrate were investigated under adverse environmental conditions, high temperature, namely, 25°C, 35°C, 45°C, low relative humidity, and high volume and velocity of airflow. The parameters of this study were three polypropylene volume fractions of 0.1%, 0.2% and 0.3% in three different matrix types of (SGC), and three drying environments. The test showed that polypropylene fibers were effective in controlling the plastic shrinkage cracking of (SGC). The use of 0.3% volume fraction of polypropylene fibers was found to he successful in combating plastic shrinkage cracking in all concrete mixes tested even under a particularly severe environment.
