Study on the influencing factors of sulfate attack performance of shotcrete under dry-wet cycle

Abstract

To study the sulfate corrosion performance of shotcrete under different conditions, by using the dry-wet cycle test of anti-sulfate attack, the effects of the water-binder ratio, the amount of cementitious material, the sand ratio, the cement type on the factors, such as concrete mass loss rate, compressive strength corrosion resistance coefficient, and relative dynamic elastic modulus, were studied respectively. The results showed that under the condition of dry-wet cycle erosion of 5% sodium sulfate solution, the mass loss of concrete decreased first, and then increased, while the compressive strength corrosion resistance coefficient and the relative dynamic elastic modulus showed the opposite trend, with an increment first and then go down. Selecting sulfate-resistant cement, reducing the water-binder ratio, or increasing the number of cementitious materials could significantly improve the anti-sulfate corrosion performance of shotcrete on which the sand ratio had little effect. SEM analysis showed that https://www.w3.org/1998/Math/MathML"> S 0 4 2 − https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003336631/207b6d57-1e20-420d-ba5c-b2a65feb8cd3/content/inline-math39_1.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> eroded into the concrete and formed AFt with hydration products to fill the internal pores of the concrete, which increased the compactness of the concrete and inhibited the further exchange of https://www.w3.org/1998/Math/MathML"> S 0 4 2 − https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003336631/207b6d57-1e20-420d-ba5c-b2a65feb8cd3/content/inline-math39_1.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> . With the increase of the cycles, the secondary hydration produced a large amount of expansive Aft, gypsum, etc, which caused the concrete to expand and crack until being destroyed.