磺化纤维素减水剂在水泥颗粒表面的吸附与作用机理

Adsorption behavior and dispersing mechanism of sulfonated cellulose based water-reducing agent on cement particle surfaces

对比研究了磺化纤维素(CS)和商品萘系高效减水剂(FDN)在水泥颗粒表面的吸附特性、ζ电位以及减水剂掺量对流动度的影响。探讨了磺化纤维素减水剂的作用机理。结果表明,减水剂吸附改变了水泥颗粒表面结构与电化学性质,通过静电斥力和空间位阻发挥分散作用。掺加CS后水泥颗粒的ζ电位较FDN的小,而CS在水泥颗粒的吸附量较FDN的大;FDN的分散作用主要依赖于ζ电位的静电斥力;CS对水泥的良好分散作用是由静电斥力和空间位阻共同作用;由于新生水化产物对静电斥力的屏蔽作用,静电斥力引起的分散作用稳定性较差,流动度经时损失大;空间位阻效应受水化影响较小,其分散作用的稳定性较好,流动度经时损失较小。

Adsorption characteristics,zeta potentials and effects on the fluidity of cement paste using two water reducing agents （traditional naphthalene sulfonated formaldehyde condensates FDN and CS sulfonated cellulose based water-reducing agent） were investigated. The sulfonated cellulose water reducing agent mechanism is discussed.The results show that the adsorption of the agents leads to change on the surface of cement particles and the electrochemical properties, because of electro-static repulsive force and steric hindrance.The zeta potentials of cement particle with CS is smaller than that with FDN,while the adsorption of CS to cement particle is bigger than that of FDN. The particle dispersion due to the adsorption of FDN depends mainly on the electrostatic repulsive forces, however, the dispersion due to the adsorption of the CS depends on a combined effect of steric hindrance and electrostatic repulsive forces. Due to the shielding effect of new hydration products on electrostatic repulsive force, the dispersion action caused by electrostatic repulsion has poor stability and big fluidity loss. while the steric hindrance effect is less affected by hydration,its dispersion action has better stability and smaller fluidity loss.