Experimental study of early-age bond behavior between high strength concrete and steel bars using a pull-out test

Abstract High strength concrete (HSC) is used extensively in practice. However, HSC is prone to cracking at early age, which can be the first step in a construction’s deterioration and its malfunction. Reinforcement is one possible way to prevent the negative effect of early-age cracks in HSC structures. The early-age bond behavior is necessary to determine the cracking width of structures. Although the bond behavior between steel bars and normal strength concrete has been studied, study on early-age bond behavior between steel bars and HSC is still lacking. This paper presents an experimental investigation on the bond behavior between steel bars and HSC of different ages using a pull-out test. Test results showed that: (1) the early-age bond strength between steel bars and HSC increased with the increase of age; (2) the bond strength between steel bars and HSC increased with the increase of concrete strength and a model for the early-age bond strength between steel bars and HSC was proposed; (3) the slip corresponding to bond strength decreased with the increase of concrete compressive strength and a model for the early-age slip corresponding to bond strength was proposed; (4) a prediction model for early-age bond stress–slip relationship between steel bars and HSC was proposed based on BPE model, which showed good agreement with test results.