Effect of Polypropylene Fiber on Sh -rinkage, Rheology and Mechanical Properties of Self Compacting Mortar

Self-consolidating concrete (SCC) is a new generation of high-performance concrete that can exhibit high deformability and can be compacted under its own weight without any external consolidation and with limited signs of segregation. Mortar serves as the basis for the workability properties of self-compacting concrete (SCC) and these properties could be assessed by self-compacting mortars (SCM). In fact، assessing the properties of SCM is an integral part of SCC design. In general، the tested SCC mixtures had higher cracking potential than the reference high-performance and conventional concretes. This may be due to the higher paste volume of SCM that resulted in greater drying shrinkage. One of the most important properties regarding the design and the durability of structures is shrinkage which seems to be increased for SCC. One highly effective technique of controlling shrinkage cracking is by reinforcing concrete with fibers. Randomly distributed fibers of steel، polypropylene، etc. provide bridging forces across cracks and thus prevent them from growing. This research focuses on the development of shrinkage in self-compacting mortar (SCM) cured at temperature of 20 ± 3°C and rein -forced with polypropylene fiber. Nine mortar mixtures are prepared containing 0 to 0. 7 per -cent of 6 and 12 mm length polypropylene fibers. The shrinkage measurements of hard -ened mortar were obtained since removing the molds and the measurements were continued up to six months. The effect of fiber content on total shrinkage of mortar was investigated by the shrinkage curves. Besides، the rheological properties of fresh fiber reinforced mortar are investigated by mini-slump test and the 28 days compressive، tensile and flexural strength of the mixtures are determined. Test results indicated that synergistic effects resulting from fibers with optimum volume fraction allow to develop SCMs in which excellent shrinkage control and mechanical properties can be obtained without jeopardizing the flow properties.