SINTEF REPORT TITLE COIN P1 Advanced cementing materials SP 1.2 F Controlling hydration development Accelerating admixtures for concrete State of the art AUTHOR(S) Roar Myrdal CLIENT(S) SINTEF Building and Infrastructure COIN – Concrete Innovation Centre Address: NO-7465 Trondheim NORWAY Location: Richard Birkelands vei 3 Telephone: +47 73 59 52 24 Fax: +47 73 59 71 36 Enterprise No.: NO 948 007 029 MVA Aker Kværner Engineering and Technology, Borregaard LignoTech, maxitGroup, Norcem A.S, Norwegian Public Roads Administration, Rescon Mapei AS, Spenncon AS, Unicon AS, Veidekke ASA and The Research Council of Norway REPORT NO. CLASSIFICATION CLIENTS REF. SBF BK A07025 Unrestricted Terje F. Rønning CLASS. THIS PAGE ISBN PROJECT NO. NO. OF PAGES/APPENDICES Unrestricted 978-82-536-0989-8 3D006020 35 ELECTRONIC FILE CODE PROJECT MANAGER (NAME, SIGN.) CHECKED BY (NAME, SIGN.) Harald Justnes Harald Justnes FILE CODE DATE APPROVED BY (NAME, POSITION, SIGN.) 2007-12-05 Tor Arne Hammer, Centre Manager ABSTRACT Accelerating admixtures affect the rates of reactions between cement and water to give an overall increase in the hydration rate. Thus, the use of accelerators in concrete provides a shortening of setting time and/or an increase in early strength development. This report gives a historical and technical overview of liquid accelerators used for concrete, their mode of actions and the characteristics of today’s commercial accelerators. Accelerators for both ‘normal’ and sprayed concrete are covered. Antifreeze admixtures for winter concreting are also discussed. Calcium chloride, the beste accelerator ever, is no longer an option due to severe corrosion hazzards in steel reinforced concrete. Inorganic salts of nitrate (for setting) and thiocyanate (for hardening) are common alternatives, although they are less efficient than calcium chloride. Many commercial admixtures today are made of mixtures of nitrate and thiocyanate. Some also contain alkanolamines and carboxylic acids or their salts. Combinations of chemicals may give interesting synergistic effects. Alkali-free shotcrete accelerators are based on aluminum sulphate as main ingredient, often combined with diethanolamine and organic acids (oxalic, formic) and/or inorganic acids (phosphorous, hydrofluoric). The report gives recommendations for further research and development of accelerators for concrete. KEYWORDS ENGLISH NORWEGIAN GROUP 1 Materials technology Materialteknologi GROUP 2 Concrete Betong SELECTED BY AUTHOR Accelerator Akselerator Cement Sement Hydration Hydratisering
Accelerating admixtures for concrete
Apr 29, 2023
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