掺超细循环流化床粉煤灰的水泥性能试验研究

通过对新拌水泥浆体的流变特性和水泥胶砂强度的测定,结合MIP与SEM等微观测试手段,研究了超细循环流化床粉煤灰(UCFA)对不同掺量循环流化床粉煤灰(CFA)水泥物理性能和力学性能的影响。结果表明:单掺CFA水泥的需水量较大,流动性差,强度下降明显；而用5%UCFA(最佳掺量)部分替代CFA,相比于单掺CFA水泥,需水量相应减少,流动度增加,水泥浆体的屈服应力τ₀和塑性黏度η值均有所减小,浆体的工作性能得到明显改善。30%粉煤灰掺量的水泥3 d强度提高6%；60%粉煤灰掺量的水泥28 d强度提高5%,达到32.5等级水泥要求；UCFA的掺入能够促进CFA水泥生成更多的钙矾石和C-S-H凝胶,改善硬化水泥浆体的孔隙结构,提高水泥强度。

Experimental study on properties of cement mixed with ultrafine circulating fluidized bed fly ash

The effect of ultrafine circulating fluidized bed fly ash (UCFA) on physical and mechanical properties of cement containing different contents of circulating fluidized bed fly ash (CFA) is studied,through rheological property and mortar strength of fresh cement paste test and combined with MIP and SEM microscopic test method,etc.The results show that cement single-mixed CFA has a larger water demand and poor fluidity,and its strength decreases significantly.Compared with cement single-mixed CFA,the cement of which CFA is partially replaced with 5% (optimum content) UCFA has a corresponding less water demand,greater fluidity ,smaller yield stress(τ₀) and plastic viscosity(η) of cement paste,and the workability of paste is improved obviously.Strength of cement containing 30% fly ash increases by 6% at 3 days,when strength of cement containing 60% fly ash increases by 5% at 28 days,reaching 32.5 cement grade requirements.The incorporation of UCFA can promote cement containing CFA to generate more ettringite and C-S-H gel and optimize pore structure of hardened cement paste,and thus improve strength of cement.