- May 10, 2017 -
The surface active agent is a material which has a significant change (usually lower) liquid surface tension or two interphase interfacial tension, and its molecule is composed of hydrophilic group and hydrophobic group in two parts. The addition of surfactant in aqueous solution, hydrophilic groups in the molecule to solution, hydrophobic groups to air, solid or nonpolar liquid and aligned, the interfacial tension of the surface tension to form directional adsorption decreases membrane water and two phases. Surface activity in liquid.
When the dosage of cement paste polycarboxylate superplasticizer, polycarboxylate superplasticizer in the molecular hydrophobic groups of directional adsorption on cement particle surface, the hydrophilic group to aqueous solution, single molecule or molecule adsorption film formed on the surface of the cement particles, the electric repulsion, the flocculation, the original structure of cement water due to a variety of factors the molecular cohesion between cement particles and the formation of open, the release of free water trapped in the flocculation structure, which is composed of polycarboxylic dispersant agent produced by molecular adsorption. After the cement is added to the water, the cement particles are wetted by the water, and the moisture is better, and the mixing water quantity is less when the same working performance is needed. The surface tension of water and the interfacial tension between water and cement particles are reduced when the surfactant is present. At the same time, poly carboxylic acid Jianshuiji molecular adsorption on the surface of the cement particles, hydrophilic groups pointing aqueous, solvent cement particle surface layer thickening, increasing the sliding ability of cement particles, and as a lubricant. If the introduction of gas type polycarboxylate superplasticizer, the lubrication effect is more obvious.