The Role of Chemical Admixtures In the Formulation of Modern Advanced Concrete

摘要

Chemical admixtures constitute indispensable ingredients for the production of modern advanced concrete.In developed countries,at least 80% of the concrete produced contains one or several admixtures.They include plasticizers,superplasticizers,retarders,accelerators,stabilizers,defoamers,foamers and shrinkage reducers,to name the most important classes.With their help it is possible to optimize the properties of fresh and hardened concrete in such way as to adapt better to local climate and processing conditions and to enhance the mechanical properties and durability.Furthermore,highly sophisticated products such as ultra-high strength concrete (UHPC) or self-levelling and self-compacting concrete (SCC) became possible only with the invention of specific high performance admixtures.This article gives an overview of major classes of chemical admixtures (e.g.PCE superplasticizers,C-S-H-PCE nanocomposites,stabilizers for SCC,shrinkage-reducing agents) and their current status of development.The main technologies will be described and their role in the formulation of modern advanced concrete will be highlighted.Finally,an outlook on potential developments in the future (e.g.improved curing agents,admixtures which enhance the ductility of concrete) will be provided.