Characteristics Of Chloride Penetration In Interfacial Zones Of Assembled Monolithic Concrete Structures

Developing assembled building has become a national strategy in the field of construction,and the building with assembled monolithic concrete structure is one of the main members.However,there are rarely targeted attention on the durability of this structure.The physical discontinuity in interfacial zone results a series of special behaviors from erosion to the corrosion and then to the durability of the resistance degradation.Therefore,it has significanceboth in science and engineering to study the characteristics of chloride penetrating into interfacial zones of assembled monolithic concrete structures for enriching the durability of concrete structure theory,promoting technology application and development of assembled concrete structure,improving the level of low carbonation in the whole life of building structure.This paper is based on the durability problem of assembled monolithic concrete structure under chloride environment,from which the key precondition of physical discontinuity in fresh-old concrete interfacial zone is grasped.Aiming at the basic issue that the chloride ion penetrating into the interfacial zones,the erosion characteristics and mechanism under different conditions such as interface roughness,compressive stress and interface crack,are revealed.This work may be the base of further studying other durability problems such as the corrosion of steel bars in the interfacial zones,the structural resistance deterioration,the structure lifetime predictionand et al.In this paper,An experiment of chloride penetrating into the interfacial zones with three interface roughness(1-2mm,6-7mm and 11-13mm)by wet–dry cycle exposure for two penetration times(60d,180d)was conducted.The results show that the chloride concentration in the interfacial zones is higher than that elsewhere.Accordingly,the interfacial zone effect(IZE)of chloride concentration distribution and its quantitative expression method(IZE index)were difined.Based on analysis of the IZE index,IZE increasing with the depth was found;the IZE decreases with the increase of penetration time.Moreover,the effect of interface roughness on the IZE is characterized by big at both ends but small in the middle,namely,the IZEs of the interface roughness of 1-2mm and 11-13 mm are closer and greater than that of the interface roughness of 6-7mm.An experiment of chloride penetrating into the interfacial zones with three compressive stress(0?0.4fc?0.8fc)by wet–dry cycle exposure for two penetration times(60d,180d)was conducted.According to the analysis of the IZE index which were defined as same as above,the influence of compressive stress on the distribution and evolution of chloride concentration in interfacial zones was obtained.On the one hand,the existence of compressive stress reduces the IZE;meanwhile,the higher the compressive stress,the smaller the interfacial effect.On the other hand,the existence of compressive stress contributed to increasing the erosion degree of chloride in interfacial zones.An experiment of chloride penetrating into the interfacial zones with three interface crack(0?50mm?200mm)by wet–dry cycle exposure for two penetration times(60d,180d)was conducted.According to the analysis of the IZE index,the influence of interface crack on the distribution and evolution of chloride concentration in interfacial zone was obtained.The results show that the existence of interface crack increases the IZE of chloride penetration,meanwhile,the wider the interface crack,the greater the degree of IZE improvement.