Freeze-thaw deterioration characteristics and micro-mechanism of solid waste incineration tailings and specified density concrete

In view of the poor durability of concrete in freezing-thawing environment and the cost problems caused by traditional improvement methods, municipal solid waste incineration tailing was used as lightweight aggregate to prepare specified density concrete which can improve the frost resistance and reduce the cost. Taking the light-weight concretes with water-binder ratio 0.3 and tailing lightweight aggregate content of 25wt%, 50wt% and 75wt% as the research objects, the freeze-thaw environment in severe cold regions was simulated. The freeze-thaw deterioration law of specified density concrete was explored by macro-indices such as spalling amount, mass loss, strength loss and dynamic elastic modulus loss, and the freeze-thaw degradation was revealed from the aspects of water absorption saturation, pore structure characteristics and bone-grain interface of specified density concrete. Finally, a damage degradation model for light concrete was developed using the damage mechanics theory. According to the findings, the durability damage of ordinary concrete caused by freeze-thaw cycle erosion is more serious than that of specified density concrete, and more mortar peeling occurs on the surface of ordinary concrete. The frost resistance of concrete can be considerably increased by the inclusion of tailing lightweight aggregate. Under the condition of freeze-thaw cyclic corrosion, the durabilities of the specified density concretes mixed with 25wt%, 50wt% and 75wt% tailing lightweight aggregate are improved by 15.2%, 30.3% and 33.3% higher than that of ordinary concrete, respectively. The porosity structure and interface characteristics of the specified density concrete are improved by strengthening the internal curing function, increasing the number of beneficial pores and increasing the strength of the bone-slurry interface, and the freeze-thaw erosion durability is improved. The freeze-thaw change rule and damage degree of specified density concrete may be studied more thoroughly thanks to the specified density concrete degradation model's fitting degree based on damage mechanics, which is above 0.97.