Degradation law of polypropylene fiber concrete under the freeze-thaw and dry-wet cycle coupling action

To study the durability of polypropylene fiber concrete (PFC) buildings in the northwest dry and cold region under the coupling effect of dry-wet and freeze-thaw cycles environment, the indoor accelerated test was designed to simulate the deterioration process of the PFC in the region under the action of dry-wet and freeze-thaw cycles environment. The mass loss rate and compressive strength loss rate were taken as the deterioration indexes. The full order time power grey prediction model was used to model the change process of the compressive strength loss rate, and the optimal structure of the model under the corresponding test conditions was determined. The results show that the mass loss rate of the specimen decreases first, then increases and then decreases until the end of the test, and the compressive strength loss rate of the specimen decreases first, then increases until the failure. In the range of fiber content taken in the test, the fiber content of 0.9 kg/m³ has the most obvious improvement effect on the resistance of the specimen under the coupling effect of dry-wet and freeze-thaw cycles. At the end of the test, the specimen with the fiber content of 0.9 kg/m³ reaches the failure standard, while the specimen under other contents is destroyed early. When the time power order h=3, the fitting degree between the full order time power grey prediction model and the original data of the deterioration process of PFC reaches 98%, and the relative error between the predicted value and the actual value is less than 0.15. The combination of indoor accelerated test and full order time power grey prediction model provides theoretical support for durability design and life prediction of concrete structures.