Performance of Softwood Soda-Anthraquinone Lignin–Polyethylene Glycol Derivatives as Water-Reducing Admixture for Concrete

Abstract

We have developed a high-performance lignin-based water-reducing admixture. In this study, softwood soda-anthraquinone lignin was modified with mono-epoxide polyethylene glycols having chain lengths of 10, 25, and 50 mol (the number of repeating units of ethylene oxide). The mortar flow and concrete slump flow tests were used to investigate the performance of the lignin derivatives as a water-reducing admixture. All tested lignin-PEG derivatives performed considerably better than a commercial lignosulfonate water-reducing admixture in the mortar flow test. In particular, the derivative with a PEG chain length of 50 mol performed excellently in both tests. The optimum PEG content for mortar dispersion was approximately 40% for lignin derivatives with a PEG chain length of 50 mol; this content exhibited a dispersing effect that was four times higher than that of the lignosulfonate water-reducing admixture. The strength of concrete containing the lignin derivatives was almost the same strength as that of concrete containing the commercial lignosulfonate water-reducing admixture.

KEYWORDS:

• Soda-anthraquinone cooking
• lignin
• Japanese cedar
• concrete admixture