Use of Innovative Admixtures in Precast/Prestressed Concrete
Charles Nmai, Lesley S-C Ko, Thomas Vickers, Jeffrey Bury, Suzanne Lianopoulos
Appears on pages(s):
chemical admixtures; fast wet-out; nanotechnology; polycarboxylate high-range water reducer; precast/prestressed concrete; rheology modifying; workability retention
Speed of production of units/structural elements and efficient use of resources are key driving forces in the precast/prestressed concrete industry and these factors significantly influence the concrete mixtures used by precast producers. For example, the production efficiencies provided by self-consolidating concrete (SCC) led to its rapid and widespread adoption in the precast industry. The development of newer high-performance concretes, such as ultra-high-performance concrete (UHPC), a continued shortage of skilled labor and societal demands with respect to sustainable concrete construction have increased the need for innovative concreting materials, in particular, chemical admixtures to address operational issues regarding concrete mixtures. Some of these issues include mixing time, flowability and flow retention, a high-quality surface finish, and very high-early strength development. In this paper, the authors present and discuss the use of innovative admixtures to address some of these performance issues; specifically, new high-range water-reducing admixtures that, respectively, provide fast wet-out of binder materials and rheology modification, nanotechnology-based strength-enhancing admixtures and a novel workability-retaining admixture.