Abstract
A novel method was proposed to improve the bond behavior of new-to-old concrete interface, which was beneficial to introduce the fiber-reinforced concrete only at the old concrete interface. This study investigated the effect of the fiber addition, strength grade of new concrete, interfacial angle, and surface treatment types on the bond behavior in terms of the new-to-old concrete through the axial tensile tests. The three-dimensional digital image correlation technique (3D-DIC) and scanning electron microscope were adopted to evaluate the variation of specimen surface strain distributions and microstructure of fiber-reinforced concrete and bond interface between new-to-old concrete. The experimental results indicated that interfacial angle and surface treatment type were significantly promoted bond behaviors, while the specimen cooperating with steel fibers had the highest bond strength. Besides, the maximum strain locations obtained from 3D-DIC method were the same as the location of the specimen failure, which indicated the 3D-DIC method can be adopted to forecast the structural failure. The microcrack strain located in the major crack was decreased with the development of the major crack. Ample crystals and Ca(OH)2 were generated in the interface between the new-to-old concrete to weaken the bond strength. Moreover, this paper provided the mechanics-driven and machine learning method to predict the bond strength. This study provides a new interface bonding method for the fabricated and large span structure to effectively avoid cracking of new-to-old concrete.
Highlights
Concrete has received wide application in engineering owing to abundant raw materials and inexpensive prices while offering high compressive strength, strong plasticity, and long durability
It is inevitable that a large number of new-to-old concrete interfaces will be formed in the large span and high-rise concrete structures and prefabricated structures due to the difference in concrete pouring time or connection joint of fabricated structure. e new-to-old concrete interface has been commonly recognized as one of the most vulnerable links in the concrete structure [1,2,3,4,5,6,7,8]
Experimental Program e effects of the fiber addition, strength grade of new concrete, interfacial angle, and surface treatment type on the bond behavior between the new-to-old concrete interface were investigated through the axial tensile test
Summary
Concrete has received wide application in engineering owing to abundant raw materials and inexpensive prices while offering high compressive strength, strong plasticity, and long durability. The axial tensile experiments were carried out to investigate the effect of the fiber addition, strength grade of new concrete, interfacial angle, and surface treatment type on the bond behavior between the new-to-old concrete in this paper. 2. Experimental Program e effects of the fiber addition, strength grade of new concrete, interfacial angle, and surface treatment type on the bond behavior between the new-to-old concrete interface were investigated through the axial tensile test. The majority of the specimen damage developed from microcracks at the edge of the interface and there was a clear region of strain concentration during the initial loading It revealed that the new-to-old concrete interface is more likely to become the damage location, once the ultimate strain registers on the specimen surface. If the structure is repaired at this stage, the structure can be prevented from being damaged while ensuring the structure’s bearing capacity. 3 When the load reached 0.8–0.9P, the major strain increased rapidly and enlarged a significant gap with the other regions, accompanied by a decrease in microcrack strains in other regions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
