Resistance of polymer modified calcium sulfoaluminate cement to sulphate attack

The effects of different dosages of EVA and SBR on the resistance of CSA paste to sulfate erosion under the condition of full soaking in sodium sulfate solution were studied. Based on the development rule of the flexural strength of polymer-modified CSA paste after immersion in Na₂SO₄ solution, combined with the flexural erosion coefficient, the resistance to sulfate erosion of polymer modified CSA paste was analyzed and evaluated. To reveal the mechanism, the effect of EVA and SBR on hydration characteristics and microstructure of CSA paste under different conditions were investigated by XRD, FTIR and SEM-EDS. Results show that the sulfate resistance coefficient increases gradually with the increase of EVA content; after adding SBR, its flexural erosion coefficient first decreases and then increases gradually with the increase of SBR content. Microscopic analysis shows that under the erosion conditions of the Na₂SO₄ solution, the amount of AFt in CSA paste decreases with the increase of EVA content, and first decreases and then increases with the rise of SBR content.