冻融循环与热老化交替作用下天然橡胶力学性能试验

Considering that the rubber isolation bearing of buildings, which is exposed to the air, will be respectively subjected to the freeze-thaw cycles and thermal aging in the wintertime period and the summertime period, the isolation effect of the bearing is very likely to be affected. To this end, the freeze-thaw cycle, thermal aging and alternation effects tests of natural rubber materials were carried out, and the mechanical properties of natural rubber materials with the changing of the time duration and the depth of deterioration were studied. The results show that: thermal aging is the main factor affecting the hardness and the stress at definite strain of rubber materials; the tensile strength and the elongation at break trend to decrease with time under the freeze-thaw cycles and thermal aging, and the influence of the alternating actions is not a simple superposition. The influence on the hardness in the depth direction of the rubber block is little, while that on the stress at definite strain is greater on the surface area of the rubber block under freeze-thaw cycles. The influences on the hardness and the stress at definite strain of the rubber block in the depth direction are rather greater in the 20 mm deep surface layer under thermal aging and alternation effects. The influence on the tensile strength and elongation at break of the rubber block in the depth direction are most obvious in the 20 mm deep surface layer. The results provide a basis for the study of the degradation of the rubber isolation bearing and the evaluation of the life cycle performance of the isolation projects.