Study on the service life prediction of freeze–thaw damaged concrete with high permeability and inorganic crystal waterproof agent additions based on ultrasonic velocity

Based on a rapid freeze–thaw test of inner-doped silicon-ash concrete specimens that were coated using three different externally coated inorganic coating methods, ultrasonic wave velocity and dynamic elastic modulus measurements were employed. The characteristics of the ultrasonic wave velocity attenuation and dynamic elastic modulus of the concrete utilizing three types of inorganic coating methods under the effect of freeze–thaw cycles were analysed. Based on the theory of damage mechanics and the evolution equation for freeze–thaw or corrosion damaged concrete, the damage evolution equations of the relative dynamic elastic modulus for three types of inorganic coated concrete were verified by a large amount of experimental data under the action of a single freeze–thaw factor. According to the relative dynamic elastic modulus formula, based on the ultrasonic wave velocity of Ababneh, the relative ultrasonic velocity was determined to be 0.7746 when the relative dynamic elastic modulus was 0.60. The equivalent freeze–thaw damage model of the ultrasonic wave velocity of the concrete was established, the concept of relative ultrasonic wave velocity was proposed, the relative dynamic elastic modulus method was verified, and the relative P-wave velocity and relative shear wave velocity of Ababneh for the three types of concrete under the effect of freeze–thaw cycles was determined for service life prediction. The above three methods can accurately predict the service life of concrete. Ultimately, the service life of concrete materials in different mix proportions and use areas will be able to be predicted using ultrasonic non-destructive testing in the future.