Abstract:

To investigate the chloride ion ingression mechanism in concrete with construction joints in coastal salt spray environment， chloride ion erosion tests were carried out on jointed concrete specimens in a salt spray environment， considered factors such as joint type， erosion time， and material composition， measured the chloride ion mass fraction at jointed and non-joint areas at different ages. The results show that at the same erosion time， the chloride ion mass fraction at the joint area is higher than that at the non-joint area， with the highest mass fraction at the direct wet joint. Along the concrete depth， the chloride ion mass fraction increases first and then decreases， reaching the maximum value at 4 mm deep from the exposed surface of concrete. Addition of crystalline admixture （CA） or a combination addition of CA and UEA expansive agent could both reduce the chloride ion mass fraction at the joint area， thereby mitigating the adverse effects of joints on the durability of concrete. The chloride ion diffusion coefficients at the non-joint area and joint area show the same attenuation trend with the salt spray time， the coefficient value at the joint area is approximately 1.3 times that at the non-joint area.

Key words: salt spray environment, direct wet joint, roughened wet joint, self-healing material, chloride ion mass fraction, apparent chloride ion diffusion coefficient