Influence of mixing procedures of superplasticizer and latex on zeta potential of cement pastes

Because of less thorough study on the properties of cement pastes with superplasticizers and latex mixed together, the influence of different mixing procedures of superplasticizers and latex on the ζ potential of cement pastes(fresh) were analyzed using the ZetaProbe instrument. The experimental results show that with adding different use level(by mass) of polycarboxylic superplasticizer(PC), the cement pastes with both PC and latex added have negative or positive ζ potential. However, the ζ potential of cement pastes with both naphthalene formaldehyde condensate superplasticizer(NF) and latex added is lower than that of cement pastes with NF added but higher than that of cement pastes with latex added. Adding NF into cement pastes with latex added, the absolute value of equilibrium ζ potential of the cement pastes is lower than that of cement pastes with NF added, cement pastes with latex added and cement pastes with both NF and latex added. Adding PC into cement pastes with latex added, the ζ potential of the cement pastes can even reach the equilibrium ζ potential of cement paste with latex added. When latex is added in, the ζ potential of cement paste with 1.0% PC added doesn't change, but the ζ potential of cement paste with 0.1% PC added decreases greatly to a certain value. The ζ potential of cement paste with NF added increases from -10 mV to -6 mV when latex is added in, and then increases slowly with the increase of use level of latex. By adding superplasticizer(NF or PC) and latex into cement pastes simultaneously or adding latex into cement pastes with superplasticizer(NF or PC) added, the adsorbed proportion of polymer particles on cement grains can be decreased.