scholarly journals Bond Behavior of Steel-Recycled Aggregate Concrete Interface After High Temperatures and Spraying Water Cooling

2021 ◽  
Vol 8 ◽  
Author(s):  
Chunheng Zhou ◽  
Jiazhang Cao ◽  
Zongping Chen
Keyword(s):  
High Temperature ◽  
Bond Strength ◽  
High Temperatures ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Water Cooling ◽  
Bond Properties ◽  
Aggregate Concrete ◽  
Concrete Interface ◽  
Ultimate Bond Strength

Using recycled aggregate concrete (RAC) in steel-reinforced concrete structure is an effective way to eliminate the adverse effects of recycled aggregate, which has an excellent application prospect. Fire has a great destructiveness to steel-reinforced recycled aggregate concrete (SRRAC) structure; hence, the bond performance of SRRAC after high temperature, as the prerequisite for the composite between steel and RAC, is the key problem for structural safety and the corresponding safety assessment after fire. In this article, the residual bond behaviors of steel-recycled aggregate concrete interface after different high temperatures and spraying water cooling were studied through the push-out test. The failure modes and load–slip curves were examined. The ultimate bond strength, residual bond strength, and elastic bond shear stiffness of specimens after high temperature and cooling for the regime of spraying water were evaluated and compared to that of natural air. A parametric analysis of temperature, replacement percentage, and studs was conducted. A calculation approach for the ultimate bond strength and residual bond strength of SRRAC after high temperature was developed based on the sensitive analysis of gray system theory and regression analysis. Results showed that the bond properties of SRRAC specimens after high temperature were decreased as exposure temperature increased. The cooling regime of spraying water has a more significant influence on the ultimate strength and residual strength than that of natural air. The specimens with studs on both flange and web have the highest bond properties after high temperature. In all the factors, the number of studs showed the largest gray relational degree to the bond strength of SRRAC. The developed approach provided a reliable prediction of bond strength for SRRAC after high temperature.

Mechanical Research on Bond-Slip Behaviors of Recycled Aggregate Concrete-Filled Square Steel Tubes

2012 ◽  
Vol 166-169 ◽  
pp. 3233-3236 ◽  
Author(s):  
Jun Tao Li ◽  
Jin Jun Xu ◽  
Zong Ping Chen ◽  
Yi Li ◽  
Ying Liang
Keyword(s):  
Bond Strength ◽  
Concrete Strength ◽  
Steel Tube ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Replacement Rate ◽  
Steel Tubes ◽  
Aggregate Concrete ◽  
Bond Slip ◽  
Ultimate Bond Strength

In order to research the interface bond-slip behaviors of recycled aggregate concrete-filled square steel tube (RACFSST), ten specimens using waste concrete were designed for launch test. The three changing parameters were concrete strength grade, embedded length and recycled coarse aggregate replacement rate. The load–slip curves of square steel tubes and recycled aggregate concrete were obtained, and starting bond strength and ultimate bond strength influenced by each changing parameter were analyzed. The results show that the replacement rate had a slight influence on the starting bond strength and ultimate bond strength, while the embedded length had the opposite effect. The shorter embedded length specimens had larger bond strength. The concrete strength had a relatively large influence on them.

Bond strength of FRP bars in recycled-aggregate concrete

2021 ◽  
Vol 267 ◽  
pp. 120919
Author(s):  
Ahmed Godat ◽  
Shaima Aldaweela ◽  
Hamda Aljaberi ◽  
Noura Al Tamimi ◽  
Ebtesam Alghafri
Keyword(s):  
Bond Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Frp Bars

Microscopic Analysis and Experimental Research on Thermal Mechanical Behavior of Natural Aggregate Concrete

2010 ◽  
Vol 129-131 ◽  
pp. 1039-1042
Author(s):  
H.Q. Yan ◽  
Q.Y. Wang
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Microscopic Analysis ◽  
Test Methods ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Strength Analysis ◽  
Aggregate Concrete ◽  
Natural Aggregate

Reinforced concrete construction is very common recently and extensively used both in industrial and commercial buildings. With the gradual rise in occurrences of fire accidents in recent years, a more thorough and quantitative understanding of the damage phenomenon in concrete structures is required. However, the mechanical behavior of concrete could actually be more complex under high temperature conditions than at room temperature. Restoration and reinforcement of the structures exposed to fire may have to be based on residual strength analysis and therefore require a correlation between temperature and mechanical properties. Thus, in order to meet the modern challenges of rapid engineering advances and societal development, further research on the concrete material and its structural behavior at high temperatures becomes extremely important. The present paper deals with investigations on the effect of high temperature exposure on the compressive strength of natural aggregate concrete. Experiments were conducted to study the compressive strength variations with increasing temperatures, up to 700 °C, and the subsequent cooling modes such as natural and spray cooling. Results show that the compressive strength gradually decreases with increasing temperatures. And micro-structural observations of the concrete specimens by means of scanning electron microscopy (SEM) were obtained. These test methods and results can be used for analyzing and investigating the behavior of recycled aggregate concrete with increasing temperatures.

scholarly journals Analysis on Mechanical Properties of Recycled Aggregate Concrete Members after Exposure to High Temperatures

2019 ◽  
Vol 9 (10) ◽  
pp. 2057 ◽  
Author(s):  
Zongping Chen ◽  
Ji Zhou ◽  
Peihuan Ye ◽  
Ying Liang
Keyword(s):  
Mechanical Properties ◽  
Energy Dissipation ◽  
Bearing Capacity ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Displacement Ductility ◽  
Energy Dissipation Capacity

In order to study the mechanical properties of recycled aggregate concrete (RAC) specimens after exposure to high temperatures, 120 RAC prism specimens, 57 reinforced recycled aggregate concrete (RRAC) specimens, and 56 steel reinforced recycled aggregate concrete (SRRAC) specimens were designed, involving two varying parameters such as recycled coarse aggregate (RCA) replacement percentage and temperature. The performance degradation of RCA materials, RRAC members, and SRRAC members after exposure to high temperatures was analyzed in depth. The research results show that after exposure to high temperatures the surface color of members may change from cinereous to gray-white. Some cracks may appear on surface of members and the mass of members may be lighter. With the increase of the experiencing temperatures, the bearing capacity (compressive, bending, and shearing) of RAC and its members are reduced, but their ductility and energy dissipation capacity have little effect on the change of high temperature. With the increase of the RCA replacement percentage, the mass loss ratio, ultimate bearing capacity, and peak deformation of each RAC and its members increase slightly, and the displacement ductility and energy dissipation capacity of the RRAC members decrease slightly. With the increase in replacement percentage of RCA, mechanical properties of RAC and their members have little effect after exposure to elevated temperatures, and the fluctuation range is within 20%.

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