超细矿渣粉和偏高岭土对硫铝酸盐水泥水化和强度的影响

掺入矿物掺合料是改善硫铝酸盐水泥(CSA)混凝土凝结硬化性能和降低生产成本的主要技术途径之一。研究了水胶比为0.4时,单掺超细矿渣粉(UFS)、偏高岭土(MK)与复掺超细矿渣粉、偏高岭土对硫铝酸盐水泥凝结时间、流动度、电阻率、抗压强度的影响,并对其1 d、28 d龄期时的水化产物进行XRD半定量分析。结果表明,单掺和复掺缩短了水泥浆体的凝结时间,但单掺偏高岭土时的缩短效果更明显,且水泥浆体的流动度随着超细矿渣粉和偏高岭土掺量的增加而减小。掺入超细矿渣粉、偏高岭土缩短了水泥浆体电阻率变化速率曲线峰值出现的时间,峰值大小与掺量成递减关系。当掺量从0%(质量分数,下同)增大到20%时,单掺超细矿渣粉试样的28 d抗压强度减小了24.7%,单掺偏高岭土试样的28 d抗压强度减小了17.7%,两者复掺试样的28 d抗压强度减小了17.3%。超细矿渣粉和偏高岭土对水泥水化产物没有明显影响,但促进了硅酸二钙(β-C₂S)的早期水化。

Effects of Ultrafine Ground Granulated Blast Furnace Slag and Metakaolin on Hydration and Strength of Calcium Sulfoaluminate Cement

The addition of mineral admixtures is one of the main technical methods to improve the setting and hardening properties of calcium sulfoaluminate cement (CSA) concrete and to reduce the cost of concrete production. The influences of ultrafine ground granulated blast furnace slag (UFS) and metakaolin (MK) on setting time, fluidity, electrical resistivity, and compressive strength of calcium sulfoaluminate cement paste with water-binder ratio of 0.4 were investigated. The hydration products cured at 1 d and 28 d were analyzed by XRD semi-quantitative analysis. The results show that both single and multiple admixtures accelerate the setting of cement paste, but the effect of MK is significant, and the fluidity of cement paste decreases with the increase of UFS and MK. The time for the peak value of electrical resistivity rate changing curve is shortened by adding UFS and MK, and the peak value decreases with the increase of UFS and MK. When the content increases from 0% (mass fraction, the same follows) to 20%, the 28 d compressive strength of the sample with UFS decreases by 24.7%, the 28 d compressive strength of the sample with MK decreases by 17.7%, and the 28 d compressive strength of the sample with both decreases by 17.3%. UFS and MK have no obvious effect on hydration products, but accelerate the early hydration of β-C₂S.