Characteristics of cement pastes containing sulphoaluminate and belite prepared from nano-materials

摘要

The sulphoaluminate phase C_4A_3S as well as β-C_2S represent an important factor for the preparation of rapid hardened sulphoaluminate-belite cement. The hydration of C_4A_3S forms ettringite and monosul-phate hydrates in addition to the liberation of aluminium hydroxide. The hydration rate of belite is much slower than that of C_4A_3S, but becomes significant at later ages. Two mixes containing sulphoaluminate (C_4A_3S) and monosulphate mix (C_4A_3S, with 8CS + 6C) in addition to belite (β-C_2S) were synthesized from nano-materials after firing at 1250 ℃. The hydration characteristics of 10% C_4A_3S or 10% C_4AS in addition to 10% β-C_2S on the expanse of OPC were studied. The results revealed that the substitution of OPC with sulphoaluminate mixes as well as belite shortens the setting times. The rate of hydration of OPC with sulphoaluminate-belite phases is increased from the formation of more sulphoaluminate hydrates and the consumption of protlandite. Also, these mixes give higher chemically combined water contents. The monosulphate hydrate is deposited in some of open pores in the dormant period of hydration that tends to increase the compressive strength of sulphoaluminate-belite cement pastes.