## 3 Tests Results and Discussion
### Results of the Pull-Out Test
#### 3.2.1 Local Bond-Slip Relationship and Bond Strength of LWAC at Room Temperature
In the  
Figure 8: Relationship curve between the temperature of the concrete and time inside the pull-out specimen: (**a**) target temperature: 300 \({}^{\circ}\)C; (**b**) target temperature: 500 \({}^{\circ}\)C.  
linear ascending branch, the specimen had no obvious cracks. In the nonlinear ascending branch, the cracks in the specimen expanded and were in a continuous cracking state. In the descending branch, the specimen was completely cracked and was penetrated by cracks. In the residual branch, the bond stress of the specimen was mainly composed of pure friction resistance. Moreover, after exposure to 300 \({}^{\circ}\)C, Figure 9a shows that the peak bond stress of the secondary pull-out test in Groups B and C was significantly higher than that in Group A. However, after exposure to 500 \({}^{\circ}\)C, Figure 9b shows that there was no significant difference in the peak bond stress of the secondary pull-out test between the experimental group and the control group. The \(\tau\)-\(s\) relationship curves of each group after being exposed to different temperatures without healing are shown in Figures 10 and 11. As shown in Figures 10 and 11, as the target temperature increased, the slope of the linear ascending branch in the figures tended to become steeper. The load of each group was the largest after being exposed to a temperature of 500 \({}^{\circ}\)C, followed by room temperature and 300 \({}^{\circ}\)C. Compared with room-temperature conditions, the maximum load of each group of specimens after being subjected to 500 \({}^{\circ}\)C increased by approximately 6% to 9%. Regarding the plateau sections of each group shown in Figures 10 and 11, the experimental group had a smaller attenuation range after entering the plateau section than Group A. This strength attenuation rate increased with the increase in the target temperature, and it can be seen that the specimens subjected to temperatures of 500 \({}^{\circ}\)C were particularly obvious. As shown in Figure 10, in the case of 300 \({}^{\circ}\)C, the peak bond stress of the Group A specimens decayed only slightly. In the case of 500 \({}^{\circ}\)C, the peak bond stress of Group A showed a phenomenon of increasing instead of decreasing. Moreover, in terms of the peak bond stress in the secondary pull-out test, there was little difference in Group A after exposure to different temperatures. Under the conditions of different temperatures, the \(\tau\)-\(s\) relationship curve of the experimental group is shown in Figure 11. As shown in Figure 11, in the case of 300 \({}^{\circ}\)C, the peak bond stress of the specimens in Group B decayed only slightly. In the case of 500 \({}^{\circ}\)C, the peak bond stress of the Group B specimens showed a phenomenon of increasing instead of decreasing. In addition, after being subjected to different temperatures, the peak bond stress of the secondary pull-out test of Group B was significantly different. In the case of 500 \({}^{\circ}\)C, the peak bond stress of the specimen decreased sharply. Furthermore, as shown in Figure 11, in the case of 300 \({}^{\circ}\)C, the peak bond stress of the Group C specimens decayed only slightly. In the case of 500 \({}^{\circ}\)C, the peak bond stress of the Group C specimens did not decrease but instead increased. After being subjected to different temperatures, the peak bond stress of the secondary pull-out test of Group C was significantly different. That is, the higher the target temperature, the smaller the limit of the bond stress. Compared with the control group, the slope in the linear ascending branch of the experimental group was higher and became steeper as the target temperature increased, as shown in Figures 10 and 11. Observing the slip growth trend after 3 mm at room temperature and 300 \({}^{\circ}\)C, the curve of the experimental group tended to be flat and slightly attenuated, while the curve of Group A exhibited an obvious downward trend.