Synthesis of Lignin-Modified Sulfanilate-Phenol-Formaldehyde Condensate and Application as Concrete Superplasticizer

Modified sulfanilate-phenol-formaldehyde condensate (MSPF) was synthesized by a reaction among soda lignin, sodium sulfanilate, phenol and formaldehyde. Optimal conditions of synthesis were obtained by studying the effects of raw material consumptions and reaction time on the dispersive property of products. Evaluation the applying performance of MSPF indicated that this new superplasticizer has an excellent water-reducing effect, and it can improve the compressive strength of hardened concrete obviously, especially the latter compressive strength. Most important of all, MSPF not only inherits the slump-maintaining capacity of aminosulfonate-based superplasticizer, but also overcomes the shortcoming of bleeding by improving the water retention capacity and reduces the segregation of mortar or concrete. Results show that MSPF is a potential superplasticizer for the high-strength and high-performance concrete.