Sulfur-free lignins from alkaline pulping tested in mortar for use as mortar additives

• Published in: Bioresource technology Vol. 84; no. 1; pp. 49 - 55
• Main Authors: Nadif, A, Hunkeler, D, Käuper, P
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2002; Elsevier Science
• Subjects: acid treatment; additives; Adhesives - chemistry; alkaline pulping; Applied sciences; ash content; Cannabis - metabolism; Cementation; Concrete admixtures; Construction Materials; Exact sciences and technology; flax; Flax - metabolism; hemp; Industrial Waste; lignin; Lignin - analogs & derivatives; Lignin - biosynthesis; Lignin - chemistry; Lignosulfonate; lignosulfonates; Materials Testing; Mortar admixtures; naphthalene; Oxidation-Reduction; Paper, paperboard, non wovens; Pilot Projects; Polymer industry, paints, wood; pulp; Reproducibility of Results; Rheology; Sensitivity and Specificity; soda pulping; Species Specificity; Spent liquors; straw; sugar content; Sulfur-free lignin; Triticum - metabolism; waste liquors; Water - chemistry; Water reducer; Wood. Paper. Non wovens; Sulfur-free lignin; Water reducer; Concrete admixtures; Lignosulfonate; Mortar admixtures; Lignin; Hemp; Chemical pulping; Mortar; Black liquor; Concrete addition; Silicates; Water reducing plasticizer; Straw; Sulfonate; Acid precipitation; Ash content; Flax; Comparative study
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/S0960-8524(02)00020-2

Sulfur-free lignin, obtained through the acid precipitation of black liquor from the soda pulping process, has been tested as water reducer in mortar. It has also been compared to existing commercial additives such as naphthalene sulfonates and lignosulfonates. The ash content and sugar content of these lignins are low in comparison to lignosulfonates, conferring on them higher purity. A procedure for small scale testing derived from the industrial norms SN-EN196 and ASTM (Designation C230-90) is presented. Specifically, all the sulfur-free lignins tested improved the flow of the mortar. Selected flax lignins performed better than lignosulfonates though still less than naphthalene sulfonates. Furthermore, certain hemp lignins gave comparable results to the lignosulfonates. Overall, the straw lignin prepared herein is comparable in performance to commercially available lignins, such as Organocell ®, Alcell ® and Curan100. The plant from which the lignin was isolated, and the process of the pulp mill are the primary influences on the performance of the lignin.