Abstract: The influence of silica fume, fly ash and ground granulated blast furnace slag on the compressive strength, chemical shrinkage and hydration products of sulphoaluminate cement under seawater condition were investigated.The results show that the compressive strength of cement paste is higher than the control sample when the dosage of silica fume is 2.5%.The compressive strength of cement paste with 10% of slag at 28 d evidently surpass that of silica fume and fly ash.The compressive strength at 60 d is even higher than the control sample.The chemical shrinkage of cement paste increase with 2.5% of silica fume, while the low pozzolanic activity of fly ash and slag during early hydration decrease the chemical shrinkage of cement paste.The hydration reaction of sulphoaluminate cement during 3 d is accelerated when the content of silica fume reached 10%, and the amount of ettringite is increased, which enhanced its early strength compared to others, but the rapidly volume expansion will destroy its internal structure and has a negative effect on the strength development.

Key words: seawater;sulphoaluminate cement;mineral admixtures;chemical shrinkage