Steel corrosion in precast reinforced concrete column-beam joint with grouted sleeve connections under chloride-rich environment

Due to the existence of pump and vent holes, precast reinforced concrete (RC) structure with grouted sleeve connections may have serious durability issues, which have almost never been studied. In this paper, a precast RC column-beam joint specimen with grouted sleeve (GS) connections, as a comparison of a cast-in-place specimen, was exposed to chloride-rich environments for 4 years. The steel corrosion and its impacts on specimen were investigated by visual inspections, X-ray computed tomography (X-ray CT) and data analysis. The test results showed that the precast RC specimen exhibited porous and loose interfaces between PVC tubes, sleeve and cement-based materials within the GS connections, leading to more severe stirrup corrosion compared to the cast-in-place specimen. In contrast, the sleeve, grouting material and their interfaces were dense so that the longitudinal bars inside had been well protected. Besides, the chloride diffusion coefficient of concrete cover in the two specimens were quantified. The corrosion level of precast RC structures with GS connections was found to grow more rapidly versus service year. On this basis, several precautions for alleviating the negative impact of GS connections on steel corrosion were proposed.