DETERMINATION OF SHRINKAGE OF FIBRE REINFORCED CONCRETE

During hardening of concrete, different chemical and physical processes occur. As a result, shrinkage of concrete develops causing cracking of construction elements. In order to reduce shrinkage, a variety of methods are used beginning from curing of concrete to using different shrinkage reducing admixtures. One possibility to reduce shrinkage is to add different types of fibres to concrete. The aim of this study was to explore the shrinkage of fibre reinforced concrete depending on the added types of fibre with different volume fractures. Altogether five series of experiments were carried out. Two series were carried out with steel fibre reinforced concrete with volume fractures of 0.32% (25 kg/m) and 0.51% (40 kg/m(3)), and two series with concrete reinforced by synthetic fibres with volume fractures of 0.44% (4 kg/m(3)) and 0.77% (7 kg/m(3)). One series of tests was performed with normal concrete. The shrinkage of the specimens was determined according to the standard ASTM C490. Steel fibre reinforced concrete with a volume fracture of 0.51% and concrete with synthetic fibres with a volume fracture of 0.77% displayed the smallest shrinkage. For concrete consisting less fibres, differences in shrinking were smaller. However, concrete without fibres showed the largest shrinkage.