Evaluation of Bond Strength of Reinforcement in Concrete Containing Fibers, Micro-silica and Nano-silica

The present study analyzes the bond stress in steel reinforcements embedded in concrete containing polymer fibers, micro- and nano-silica particles. For this purpose, 36 cylindrical (with a diameter of 10cm and height of 15cm) and 36 cubic (101010cm) specimens containing different contents of additives and three types of cement strength grade (i.e. 32.5, 42.5 and 52.5MPa) were constructed and subjected to pull-out and compressive strength tests, respectively. The experimental observations were then compared to previously proposed models available in the literature. The results indicated that microand nano-silica particles, compared to fibers, had more impacts on improving the reinforcement-concrete bond strength. Moreover, the highest bond strength was observed for the specimen containing equal content of microand nano-silica particles. An acceptable agreement was also obtained between the results of current study and previous models, highlighting the capability of the proposed models in prediction of the actual behavior of such specimens.