Surface Charge Properties of Marble Powder and its Effect on the Formation of Hydrates in Cement Paste

Replacing part of cement with waste stone powder can reduce the use of cement, thus reducing energy consumption and CO2 emission. Different stone powders affect the properties of cement-based materials differently. It is important to clarify the effect of the surface properties of the stone powder on the properties of cement-based materials. In this paper, the charge properties of marble powder and its effect on the formation of hydrates were investigated. Zeta potential was used to study the charge properties of the marble surface. Parallelly, the morphology of hydrates on the surface of the cement and marble particles at a very early hydration age was observed by using SEM. Finally, the influence of the surface charge properties of the marble particles on the formation of hydration products of cement was discussed. The results showed that the marble particles have specific adsorption of Ca2+ (chemical adsorption). Therefore, the marble particles in the simulated solution can adsorb a large amount of Ca2+, thus achieving a high potential value and facilitating the formation of hydrates on their surface. However, the adsorption of Ca2+ towards the surface of the cement particle is driven by a relatively weak electrostatic force. Compared with the marble particles, less Ca2+ ions are adsorbed, and thus, fewer hydrates are formed on the surface of cement particles.