## 3 Test Results and Analysis
### Changes in Tensile Strength After Freeze-Thaw Cycles  
The tensile strength of specimens after different numbers of freeze-thaw cycles is shown in Figure 9. Within the first 75 freeze-thaw cycles, the splitting tensile strength of ordinary concrete decreases significantly faster than that of rubber concrete, and the decrease of rubber concrete is relatively slow. After 75 freeze-thaw cycles, the splitting tensile strength of ordinary concrete continues to decrease, and the rate of decrease in rubberized concrete is accelerated compared with that during the first 75 freeze-thaw cycles. Overall, it seems that the addition of rubber substantially reduces the splitting tensile strength of concrete. However, during the freeze-thaw cycle, the addition of rubber slows down the reduction in splitting tensile strength and improves the frost resistance of concrete. The reason why the addition of rubber can reduce the rate of decrease in the split tensile strength of concrete after freezing and thawing is that, on the one hand, as an elastic material, when the concrete specimen is subjected to force, rubber can slow  
Figure 8: Damage diagram of the compressive specimen after different number of freeze–thaw cycles.  
Figure 7: Deterioration value of compressive strength of specimens after different numbers of freeze–thaw cycles.  
down the degree of force of the concrete. On the other hand, the addition of rubber can introduce more bubbles into the concrete, increasing the antifreeze property of the concrete and reducing the internal damage of the concrete after freezing and thawing, thus slowing down the decrease in split tensile strength.  
The curve of the tensile strength deterioration value is shown in Figure 10. With the increasing number of freeze-thaw cycles, the splitting tensile strength of ordinary concrete decreases by the largest proportion. After 50 freeze-thaw cycles, the splitting tensile strength of ordinary concrete in group A drops to 82%, while that of the concrete with rubber is above 85%, and the splitting tensile strength of group B with 10-mesh rubber decreases by the least, by 10%. After 75 freeze-thaw cycles, the splitting tensile strength of group A of ordinary concrete decreases to 66%, while that of the concrete with rubber is above 75%, and the splitting tensile strength of group B with 10-mesh rubber decreases by the least, by 15%. After 100 freeze-thaw cycles, the splitting tensile strength of group A of ordinary concrete drops to 53%, while that of the concrete with rubber is above 63%, and the splitting tensile strength of group D with 30-mesh rubber decreases by the least, by 29%. After 125 freeze-thaw cycles, the splitting tensile strength of group A of ordinary concrete is less than half of the initial value, while that of the rubberized concrete is above 53%, and the splitting tensile strength of group D with 30-mesh rubber decreases by the least, by 40%. Overall, the splitting tensile strength of ordinary concrete in group A is rapidly reduced. For the rubber added to groups B, C, and D, the decline rate in the first period is smooth, and the decline rate in the later period is accelerated compared with that in the first period, among which group D has the slowest decline. This shows that the addition of rubber can slow down the reduction in the splitting tensile strength of concrete, and the best performance of the experimental group in the test group is that of the 30-mesh rubber group.  
Figure 10: Deterioration in tensile strength of specimens after different numbers of freeze–thaw cycles.  
Figure 9: Tensile strength of specimens after different numbers of freeze–thaw cycles.  
Figure 11 shows the damage diagram of tensile specimens after different numbers of freeze-thaw cycles. With the increasing number of freeze-thaw cycles, the loading time of specimens before damage gradually becomes shorter, but the change in specimen damage morphology is not obvious. Compared with ordinary concrete, the cracks after damage to rubber-mixed concrete are more complete and clear.