Abstract: Silica fume, fly ash and slag were chosen as mineral admixture， the influence of mineral admixture on cement hydration products, structure and morphology of hardened cement paste were analyzed by means of SEM and XRD. The mechanism of acid corrosion to cement was discussed and proportion optimization of mineral admixture was carried on to improve the acid resistance of portland cement. The results show that mineral admixture is beneficial to reduce alkalinity and improve the pore structure of hardened cement paste. When silica fume, fly ash and slag accounted for 5%, 10% and 15% of cement separately are introduced together, the acid resistance of portland cement is the best.

Key words: mineral admixture%acid resistance%coefficient of compressive strength