水玻璃模数对矿渣基胶凝材料水化特性及动力学的影响

Effects of Water Glass Modulus on the Hydration Properties and Kinetics ofSlag-based Cementitious Materials

为进一步明确水玻璃在矿渣基胶凝材料(SCM)水化过程中的作用机制,借助力学性能测试、X射线衍射和热重分析考察了水玻璃模数对SCM抗压强度和水化产物的影响。同时,采用等温量热法和Krstulovic-Dabic动力学模型,讨论了SCM结晶成核与晶体生长(NG)、相边界反应(I)和扩散(D)过程的水化动力学参数与水玻璃模数之间的相关性。结果表明,在水玻璃模数为0.7~2.5范围内,SCM的主要水化产物均为水化硅(铝)酸钙凝胶,其生成量随水玻璃模数的增加逐渐降低。低水玻璃模数(Ms=0.7)条件下,大量低聚合度硅(铝)酸钙凝胶的生成造成了SCM抗压强度的降低。动力学研究表明,SCM的水化过程符合Krstulovic-Dabic动力学模型,控制历程均表现为NG→I→D。水玻璃模数对SCM水化过程的作用机制在于对各阶段反应速率常数的影响,NG、I和D过程的反应速率常数均随水玻璃模数的增加逐渐降低,导致了SCM水化反应速率下降。

To improve the action mechanism of water glass on the hydration of slag-based cementitious materials(SCM),the influence of water glass modulus on the compressive strength and the hydration products of SCM was investigated by means of mechanical test,X-ray diffraction and thermogravimetric analyses.Meanwhile,the correlations between the kinetic parameters of crystallization nucleation and crystal growth(NG),phase boundary reaction(I)and diffusion(D)process of SCM and the water glass modulus were discussed using isothermal calorimetry and the Krstulovic-Dabic kinetic model.The results showed that the main hydration products of SCM were calcium(aluminum)silicate hydrate gels.The amount of hydration products decreased with the increase of water glass modulus in the range of 0.7—2.5.Under the condition of low water glass modulus(Ms=0.7),the formation of a large amounts of calcium(aluminum)silicate hydrate gels with low polymerization degree resulted in the reduction in compressive strength.Kinetic studies indicated that the hydration process of SCM conformed to the Krstulovic-Dabic kinetic model that the control process was shown as NG→I→D.The action mechanism of water glass modulus on the hydration of SCM lies in its effect on the reaction rate constants of NG,I and D processes,which decreased with the increase of water glass modulus,leading to the reduction in hydration reaction rate of SCM.