Research On Sulphoaluminate Cement Based Materials

Sulphoaluminate cement has the advantages of rapid hardening, early strength,high strength, impervious and great durability. Due to the raw materials, the production cost of SAC is higher than Portland cement, which restricts the application of SAC in engineering field, meanwhile, adding mineral admixtures in SAC can degrade performance of SAC.The paper which based on NSFC(51178363) added 40% mineral admixtures(MP FA) in SAC aimed at reducing the price of it, and studied the amount of mineral admixtures on the effect of physical properties mechanical property and air shrinkage of SAC, tried to modified the lowcost SAC based cementitious materials based on chemi-excitation effect crystallization effect particle effect admixture adjusting and complementarity advantages method consider of working properties mechanical properties micro performance and durability performance. Extraordinarily, chemi-excitation effect was the major modification method and take the compressive strength as the main index of modification effect. Research results were as follows:1. MP and SF had little effect on setting time of SAC and FA retarded slightly, FA and MP had positive effect on water requirement of normal consistency and fluidity and SF also had some positive effect when the amount of SF was on more than 5%, FA and MP reduced the mechanical property when SF was on more than 5% it can improve compressive strength, mineral admixtures clearly restrained air shrinkage of SAC of which FA and SF was better than MP.2. M had favorable modification effect on the FA-SAC system when the amount was 2%, there was clearly effect. The highest compressive strength of 2h 3d 7d 28 d and 1y had improved 134% 93% 62% 61% and 63% respectively when adding M. The research showed that M promoted more AFt and alumina gel produced in early age, and promoted FA participated in the hydration reaction in later period, the M might lead to poor crystalline forms of Aft and when it accumulates to certain degree may reduce compressive strength of 7d as the the prolong of hydration time, this phenomenon disappeared.3. The compatibility of superplasticizer with cementitious materials followed this order : KH-5>KH-6>AS>FDN, the ultrafine components on the effect of FA-SAC system followed this rule: nano-silica(1%-2%) > CC(1%-3%) > SF(≤10%), orthogonal experiment showed that different components on the modification effect of MP-FA-SAC system followed this rule chemi-activator>SF>CC and the optimal amounts were 4%、6%、3% respectively.4. The compressive strength of MP-FA-SAC system was better than FA-SAC system when combined MP and FA as the ratio of 2:1 adding in SAC, compressive strength of 2h 3d 7d 28 d and 90 d had improved 7% 16% 23.7% 20% and 40%respectively. When adding modification components compressive strength of FA-SAC system of 2h 3d 7d 28 d and 90 d had improved 17.5% 42.8% 51.8% 61.0% and 66.7% respectively, the MP-FA-SAC had improved 2.3% 14.8% 13.8% 26% and 15.4% respectively. The compressive strength of both systems were improved after eroded 90 days, MP-FA-SAC system had better performance of the two.