Material Deterioration Mechanism Of Crts ?Type CA Mortar Under Acid Rain Enviornment

The deterioration mechanism of slab ballastless track cement emulsified asphalt mortar ?CA mortar? under simulated acid rain enviornment had been studied. The SEM-EDAX data indicated that the white crystalline substance on the surface of specimens in the acid was CaSO₄·nH₂O and the DTA results showed that the white crystal is CaSO₄·H₂O. The dissolution of C-S-H gel caused by the damage of alkaline environment and the salt crystallization attack are the main cause for the cracking, peeling, decreased compressive strength and elastic modulus of CA mortar. ²⁹Si NMR analysis illustrated that thaumasite form of sulfate attack ?TSA?appeared in CA mortar under experimental conditions.CA mortar from Suining-Chingqing ?Suiyu? line and Chen-Mian-Le intercity passenger special railway line in southwest acid rain area was studied. Comparative analysis on the stress-strain curve of CRTS ? type cement emulsified asphalt mortar ?CA mortar? showed that the CA mortar becomes hardening, embrittlement, damping-reduced, and vibration attenuation performance-declined under long-term operating environment, and the compressive strength and elastic modulus didn't meet the standard requirements anymore; It could be found that the CA mortar wasn't attacked by the thaumasite type sulfate erosion according to the data of XRD SEM-EDAX, FTIR. Salt crystallization under acid rain erosion is not the main cause of the performance deterioration; The quantitative analysis of asphalt in CA mortar combined with XRD and TG-DTA data, found that the content of asphalt reduced in the CA mortar under long-term operating environment; Analysis of asphalt in CA mortar based on the curves of TG-DTA and FTIR indicated that the loss of asphaltene under the comprehensive action of train load and water was the primarv reason for the performance deterioration of CA mortar.