EFFECT OF GLASS FIBER ON SHRINKAGE AND MECHANICAL PROPERTIES OF HIGHLY FLOWABLE CEMENT PASTE

Self-consolidating concrete (SCC) is a new class of high-performance concrete that can spread readily into place under its own weight and fill restricted sections as well as congested reinforcement structures without the need for mechanical consolidation and without undergoing any significant separation of material constituents due to its unique flow behavior. SCC mix design often involves the use of high paste volume and low coarse aggregate content, thus leading to relatively high shrinkage and higher cracking potential compared to conventional concrete. The use of fibers depending on the fiber type and fiber content may considerably increase the toughness, energy absorption capacity, reduce cracking, improve the impact resistance and durability of cement composites. One of the most important properties regarding the design and the durability of structures is shrinkage which seems to be increased for highly flowable cement paste (HFCP). Glass ber reinforcement can be an excellent solution for shrinkage, bending and tensile resistance problems of HFCPs. This research focuses on the development of shrinkage in highly flowable cement paste, which plays an important role in shrinkage of SCC, reinforced with glass fibers. five cement paste mixtures were prepared containing 0, 0.1, 0.2, 1 and 2 percent of 6 mm long glass fibers (with aspect ratio of 150). The effect of fiber content on total shrinkage of the cementitious material is investigated in this research using shrinkage curves over 240 days. Besides, the rheological properties of fresh fiber reinforced cement paste are investigated by mini-slump test and the 28 days compressive and flexural strength of the mixtures are determined. Test results indicated that Synergistic effects resulting from fibers with optimum volume fraction allow to develop HFCP in which Excellentechanical properties can be obtained without jeopardizing the flow properties.

کلیدواژه ها:

self-consolidating concrete ، highly flowable cement paste ، shrinkage ، glass fiber