Reinforced concrete structures that are strengthened with fiber-reinforced polymers frequently suffer dynamic loadings. The success of this strengthening method depends on the effectiveness of the bond between the fiber-reinforced polymer sheet and concrete. Determining the bond behavior between the fiber-reinforced polymer and concrete substrate is an important issue in technology because the typical failure mode of fiber-reinforced polymer-to-concrete joints is debonding of the composite from the concrete substrate. Although numerous experimental studies have investigated this static bond behavior, experimental data concerning dynamic tests on maximum bond stress, ultimate load, and the bond-slip relationship of the interface between basalt fiber-reinforced polymer sheets and concrete under different strain rates are lacking. This study presents an experimental investigation of the dynamic performance between the basalt fiber-reinforced polymer sheet and concrete under different strain rates. Double-lap shear specimens were used in the tests. The dynamic test results are reported and discussed in this paper to evaluate and compare the influence of the strain rate on the dynamic maximum bond stress, ultimate load, as well as the bond-slip relationship between the basalt fiber-reinforced polymer sheets and concrete. The data show that the maximum bond stress, ultimate load, and bondslip relationship are sensitive to the strain rate. The test results indicate that (1) the dynamic maximum bond stress of the basalt fiber-reinforced polymer-concrete interface increases with the increase of the strain rate; (2) the dynamic ultimate load of the basalt fiber-reinforced polymer-concrete interface increases with the increasing strain rate as a logarithmic function; and (3) the strain rate has no effect on the slip at the maximum bond stress, and the dynamic bondslip relationships of basalt fiber-reinforced polymer-concrete interface under different strain rates are similar. The calculation models of the dynamic maximum bond stress, ultimate load, and bond-slip relationship were established through a regression analysis of the dynamic test data while considering the influence of the strain rate.

No abstract

No abstract

No abstract

High-performance concrete (HPC) is widely used. However, HPC with a low water-to-binder ratio generally experiences rather high autogenous shrinkage. If restrained, autogenous shrinkage can result in the development of residual tensile stresses that may be sufficient to cause cracking at an early age. Fly ash (FA) has been utilised as a mineral admixture to reduce shrinkage and improve the durability of HPC. Although shrinkage development and early-age cracking resistance of HPC under restraint have been investigated, research on the stress relaxation of HPC with FA by ring tests is limited. Restrained ring tests on the cracking resistance of HPC using FA as 0, 20, 35 and 50% by weight replacements of cement were conducted. The test results showed that: free shrinkage decreased with an increase in FA replacement ratio; the actual strain in the steel ring decreased with increasing FA replacement; the residual stress of the concrete ring decreased with increasing FA replacement; the ratio of maximum residual stress to time-dependent splitting tensile strength decreased with an increase in FA replacement; the relaxed stress was almost constant when the FA replacement ratio increased from 0 to 20%, and decreased when the FA replacement ratio increased from 20% to 35% and 50%; and the cracking potential based on stress rate decreased when the FA replacement ratio increased from 0 to 20% and 35%, and increased when the FA replacement ratio increased from 35% to 50%.