Preparation of Novel Lignin-Based Cement Dispersants from Isolated Lignins

Abstract

Lignin-based amphiphiles were prepared from the waste liquors of softwood and hardwood kraft pulpings (SKLliq and HKLliq, respectively) and their isolated lignins (SKL and HKL, respectively) by a reaction with several epoxylated polyethylene glycol analogues: polyethylene glycol diglycidylether (PEGDE), its monoglycidyl ether (EPEG), and dodecyloxypolyethylene glycol glycidyl ether (DAEO). The effect of these amphiphiles on cement dispersity was examined at 6°C and 20°C. Generally, only half the amount of EPEG- and PEGDE-series (e.g., 0.4%) was required to achieve the same cement dispersibility (e.g., Γp value of 2) compared to lignosulfonate (LS) (e.g., 0.8%). DAEO-lignin derivatives with the highest surface activity did not show cement dispersibility, suggesting no correlation between cement dispersibility and surface activity of the amphiphiles. Thus, together with the test of bending strength, it was found that the amphiphiles prepared from isolated lignins and EPEG were promising cement dispersants, which were available even in the wintertime without losing mechanical strength.