ABSTRACT
Radical Concrete Technology. Edited by R K Dhir and P C Hewlett. Published in 1996 by E & FN Spon, 2-6 Boundary Row, London SE1 8HN, UK. ISBN 0 419 21480 1. ABSTRACT. Lignosulphonates originating from the pulp and paper industry are well known raw materials for the production of water-reducing admixtures for concrete. Traditional sulphite and kraft pulping processes which are noted for their contribution to air and water pollution can now be replaced by more environmentally friendly technologies. One of them, the ALCELL® organosolv pulping process, has minimal impact on the environment and produces a pure lignin as one of the co-products to the pulp. A modified sulphomethylolated ALCELL® lignin was found to be an efficient water-reducing admixture for concrete. It was evaluated according to CSA Standard CAN3-A266.6-M85 in both non-air-entrained and air-entrained concrete. The workability, unit weight, air content and setting time of the fresh concrete as well as compressive strength, length change, spacing factor and durability of hardened concrete were determined. After 1500 cycles in the automated freeze-thaw apparatus the durability specimens were placed at a natural marine exposure station for further monitoring. The results of this study indicated that the new ALCELL® lignin-based admixture meets the requirements of CSA Standard CAN3-A266.6-M85 and can be classified as a Type SPRsuperplasticizing admixture with set-retarding characteristics. Even with a spacing factor of 0.79 mm it was found that superplasticized concrete was resistant to freezing and thawing. Keywords: Air-entrainment, Air-void spacing factor, Compressive Strength, Durability, High range water-reducing admixture, Length change, Setting time, Slump loss, Superplasticizer. Mr Jiri Zhor is a doctoral candidate in the Department of Civil Engineering at the University of New Brunswick in Fredericton, N.B., Canada. After 10 years of experience in areas of concrete structures, materials, repairs and testing, he has been engaged in research on concrete admixtures since 1986. His current research interests are on the chemistry of superplasticizers for concrete and properties of fresh concrete. Dr Theodore W.Bremner is a professor of civil engineering at the University of New Brunswick in Fredericton, N.B., Canada. He is chairman of ACI Committee 213 Lightweight Aggregate Concrete and a member of several other ACI technical committees. His research interests include structural lightweight concrete, durability of concrete structures and concrete in the marine environment.
