Guo, Haolong, Wang, Hailong, Xue, Huijun, Li, Hao, Li, Yue, and Wei, Lisi
Concrete is a commonly utilized material in the construction of infrastructure in Northwest China. However, its durability in saline environments is hindered by its susceptibility to salt and freeze-thaw erosion. By incorporating basalt fibers (BF), reticulated polypropylene fibers (RP), and calcium carbonate whiskers (CW) into concrete, the crack resistance of the material can be enhanced from the micro to macro level. Previous research has yet to thoroughly examine the enduring erosion resistance of CW-BF-RP concrete (CBPC) over extended periods amidst diverse salt-freezing conditions. Additionally, the precise mechanism through which CW impacts the deterioration of the interfacial transition zone (ITZ) between fibers and the cement matrix remains incompletely elucidated. This study examines the variability in compressive strength, mass loss, and damage degree of CBPC when exposed to various types of salts (sulfate/chloride) and erosion conditions of different concentrations. And the corrosion mechanism of CBPC in different freeze-thaw conditions was revealed by Fourier Transform Infrared Spectroscopy, Thermogravimetry, Nuclear Magnetic Resonance, Scanning Electron Microscopy and Atomic Force Microscopy. The findings suggest that the strength reduction rate, mass loss rate, and damage degree of CBPC increase with the rise in salt concentration and freeze-thaw cycles. The three indicators in chloride salt conditions are significantly higher than FW, with values of 78.64%, 223.6%, and 309.0%, respectively, compared to 47.63%, 155.4%, and 162.4% in S-3, indicating that CBPC exhibits greater resistance to sulfate salts than chloride salts. The consumption of CH is a key factor in the occurrence of AFt and Friedel's salt and pore degradation. Concrete pore degradation between 3.25μm and 6.81μm leads to rapid disintegration, with detachment of the mortar occurring when the pore size reaches 31.95μm. CW maintains its integrity in sulfate salt and FW conditions, but experiences severe corrosion in chloride salt. At this point, the maximum ITZ of 7.5 μm for BF is less than that of 22.8 μm for RP, indicating that the bonding of BF to the matrix is stronger than that of RP. The longitudinal height difference of fiber-cement aggregate ITZ in chloride conditions ranges from 42.8 nm to 59.8 nm, creating water channels of 5.70μm to 6.91μm, thereby weakening the adhesion of the matrix. Finally, a Wiener stochastic model is established for life prediction under different salt-freezing conditions, with the maximum life expectancy in sulfate conditions being 1.26–1.86 times that in chloride conditions. These research findings can provide theoretical references for the durability design of concrete in the salt-freezing areas of northwest China. • Add CW-BF-RP into concrete to study the freeze-thaw endurance degradation law. • The decrease rate of each index of concrete increases with the increase of salt concentration. • CW suffers from severe corrosion due to the decrease of concrete alkalinity in chloride salt condition. • ITZ deterioration in chloride salt condition is significantly greater than that in sulfate and FW conditions. • Wiener stochastic model can effectively characterise the endurance life of concrete in salt-aggressive environments. [ABSTRACT FROM AUTHOR]