Deterioration of concrete under the coupling action of freeze–thaw cycles and salt solution erosion

Abstract

Abstract In this article, the deterioration law of concrete under the coupling action of freeze–thaw cycles and salt solution erosion is studied through the comprehensive thermal analysis, the field emission electron microscope, and the nuclear magnetic resonance, and the influence of salt solution type and salt solution concentration is considered. The results show that the freeze–thaw damage of concrete in the salt solution is the combined effect of the expansion pressure of the freeze–thaw erosion product, the crystallization pressure of the salt solution, and the frost heave pressure of the fresh water; the damage degree increases with the increase of freezing and thawing cycles; the damage degree of concrete in the chloride solution is greater than that in the sulfate solution and fresh water before 150 freezing and thawing cycles; the damage degree of concrete in the sulfate solution is greater than that in the chloride solution after 150 freezing and thawing cycles; the pores size of concrete in the salt solution is larger than that in fresh water, the main peak of the difference of pore size proportion shifts to the harmful pore area, and the secondary peak and third peak appear in the seriously harmful pore area; the pore diameters of the main peak, the secondary peak and the third peak of concrete in different salt solution, and the limiting pore diameters are 0.0662, 1.145, and 10.116 μm, respectively; the safe service life of concrete in salt solution environment after freezing and thawing cycles is predicted by the Weibull distributed life evaluation model. The maximum life after the freeze–thaw cycle is 33 years, which is at least 42% lower than that in the fresh water environment after freezing and thawing cycles.