石膏掺量对高贝利特-硫铝酸盐水泥性能的影响

Influence of Gypsum on Performance of High Belite-sulphoaluminate Cement

利用循环流化床(CFBC)固硫灰代替部分铝矾土、石膏等原料制备高贝利特-硫铝酸盐水泥,并采用XRD、SEM等方法研究了石膏掺量对该水泥凝结时间、抗压强度、水化产物和微观结构的影响。结果表明,利用固硫灰等原料制备的水泥熟料的矿物组成主要有C2S、C4A3S、铁相等;掺入石膏会缩短水泥的凝结时间,最佳石膏掺量为9%;水泥3d、28d净浆强度可以达到39.00MPa和82.59MPa;掺入适量石膏能促进C4A3S和C2S水化,掺量不足会使AFt向AFm转化,掺量过大反而会阻碍C4A3S的水化,进而影响水泥强度;不同石膏掺量下的水泥水化产物主要为AFt、AFm、C-S-H凝胶和铝胶等。

High belite-sulphoaluminate cement was prepared by using circulating fluidized bed combustion （CFBC） fly ash as raw materials. The effects of gypsum on setting time, compressive strength, the hydration products and microstructure of high belite-sulphoaluminate cement were studied by XRD and SEM, etc. The experimental results show that the main mineral compositions of high belite-sulphoaluminate cement clinker include C2 S, C4 A3 S and C4 AF; and gypsum can shorten the setting time of high belite-sulphoaluminate cement. The optimal content of gypsum is 90% and the compressive strengthes of high belite sulphoaluminate cement are 39.00 MPa at 3 d and 82. 59 MPa at 28 d. The proper content of gypsum can promote the hydration of C4 A3 S and C2 S, AFt can transform into AFm when the gypsum is shortage, and the excessive gypsum can prevent hydration of （24 As S, which affects the strength of cement. No matter the amount of gypsum, the main hydration products of high belite-sulphoaluminate cement are ettringite（AFt）, calcium monosulphoaluminate （AFro） ,C-S-H gel and alumina gel.