Study on corrosion resistance and mechanical properties of cast-in-place concrete under sulfate attack
To improve the corrosion resistance of cast-in-place concrete in regions with potent sulfate-saline soils,calcined metakaolin was used to replace 0,5%,15%,25%,and 50%cement.Prolonged immersion tests were conducted in pure water,5%Na2SO4,10%Na2SO4,and 10%Na2SO4+10%NaCl solution.The flexural strength,compressive strength,relative dynamic modulus of elasticity,mass loss rate,volumetric expansion rate,and effective porosity of the specimens at 1 d,3 d,7 d,14 d,28 d,and 90 d of age were examined.The results show that(1)The addition of calcined metakaolin improves the flexural strength,compressive strength,and corrosion resistance of cast-in-place concrete.When the content of calcined metakaolin is 25%,the specimens exhibit optimal flexural and compressive strength,the most stable relative dynamic modulus of elasticity,and superior sulfate attack resistance.(2)Calcined metakaolin effectively reduces the effective porosity and mass loss rate of cast-in-place concrete while significantly improving the volumetric stability of the specimens.These research results can offer a theoretical foundation for the engineering application of calcined metakaolin in elevating cast-in-place concrete performance within sulfate-saline soil environments.
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