Study of effect of paste volume, water to cementitious materials and fiber dosages on rheological properties and in-situ strength of self-compacting concrete

As a vibration- free concrete, self- compacting concrete (SCC) can be easily used in the absence of consolidation, therefore; it is a good option for repairing and retrofitting concrete structures. The quality of repair layer is highly effective on a successful repair. Accordingly, in this study, factors affecting the quality of fiber-reinforced self-compacting concrete repair layer, including paste volume, the ratio of water to cementitious materials and the amount of fiber, are discussed. For this purpose, the in-situ strength of repair layers and core and non-core sample cubes are determined using pull- off method. Also comparisons between in-situ strengths in different methods (with and without core, on cubes or on repair layer) with compressive and tensile strength of specimens is done. Results show that, considering the great influence of shrinkage and tensile strength, with reduced paste volume, cementitious material and increased fiber, the in-situ strength of repair layer increases. Moreover, we found that even in the best condition of concrete substrate layer (i.e. saturated surface dry) a repair layer has a lower strength than a cube specimen. Also, presence of fibers has the huge effect on results of pull-off test depends on the method of the test (with or without core).