- Author
- Bentz, D. P. | Peltz, M. A. | Snyder, K. A. | Davis, J. M.
- Title
- VERDiCT: Viscosity Enhancers Reducing Diffusion in Concrete Technology.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Journal
- Concrete International, Vol. 31, No. 1, 31-36, January 2009
- Keywords
- concretes | viscosity | diffusion | reinforced concretes | structures | electrolytes | evaluation | mortar | chloride | exposure | penetration
- Identifiers
- viscosity measurements relative to value for distilled water; electrical conductivity reductions for solutions with various viscosity modifiers; length of exposure to chlorides
- Abstract
- Reinforced concrete structures are susceptible to attack by elements of the environment including chloride and sulfate ions. Past attempts at increasing service life have generally focused on limiting the ingress of these deleterious elements by producing less permeable concrete. Lower water-cementitious material ratios and the addition of fine pozzolans such as silica fume contribute to a denser cement paste matrix. Such mixtures are often classified as high-performance concretes. These mixture modifications, however, also typically contribute to an increased temperature rise and increased autogenous shrinkage, both of which increase the concrete's propensity to undergo early-age cracking. Thus, attempts to produce less permeable concrete can be compromised by the existence of just a few through-depth cracks. A new approach to increasing concrete service life involves the use of carefully selected viscosity modifiers to substantially increase the viscosity of the concrete pore solution and slow down diffusion through the pore solution. Doubling the service life of a specific concrete may be possible by doubling the viscosity of its pore solution. This approach has been assigned the acronym VERDiCT: viscosity enhancers reducing diffusion in concrete technology.