掺黏度改性剂与减水剂水泥浆的zeta电位研究

Study on Zeta Potential of Cement Pastes with Viscosity Modifying Admixtures and Superplasticizers

采用zeta(ζ)电位仪研究了黏度改性剂(VMA)、减水剂单掺以及VMA与减水剂复掺对水泥浆ζ电位的影响.结果表明:由于水泥粒子吸附VMA或减水剂分子,因此单掺VMA或减水剂水泥浆ζ电位降低.VMA与聚羧酸系减水剂(PC)同掺水泥浆表现出来的主要是水泥粒子吸附PC分子后的ζ电位特性;VMA与萘系减水剂(NF)同掺水泥浆ζ电位绝对值比单掺NF水泥浆低.无论是滴加PC到掺VMA水泥浆中还是滴加VMA到掺PC水泥浆中,水泥浆ζ电位都有所提高;VMA的加入使得掺NF水泥浆的ζ电位升高,但仍低于两者同掺水泥浆的ζ电位;在掺VMA水泥浆中,当NF滴加量达到一定值时,水泥浆ζ电位绝对值甚至高于两者同掺水泥浆ζ电位绝对值.

The influence of viscosity modifying admixtures（VMA） and superplasticizers and mixing of these two agents on zeta（ζ） potential of cement pastes（fresh） were analyzed using the ZetaProbe instrument. The experimental results show that since cement grains adsorb VMA or superplasticizer molecules, the potential of cement pastes with VMA or superplasticizer decreases. The ζ potential of cement pastes with both VMA and polycarboxylic superplasticizer（PC） shows that cement grains primarily adsorb PC molecules, whereas the absolute value of ζ potential of cement pastes with both VMA and naphthalene formaldehyde condensate superplasticizer（NF） is lower than that with only NF. To add PC into cement pastes with VMA or to add VMA into cement pastes with PC will result in the ζ potential increase. The ζ potential of cement pastes with NF increases from --8 mV to --3 mV as VMA is added in. However, it is still lower than that with both VMA and NF. The ζ potential of cement pastes with VMA decreases as NF is added in, and the ζ potential absolute value is higher than that with both VMA and NF when the use level of NF increases to a certain value.