Effects of Temperature on the Development of Low Permeability in Concretes

About the report:

This study evaluated the effects of temperature on the strength and permeability of concretes containing pozzolans (fly ash and silica fume) and slag. Two test programs were conducted. In the first, one control and five experimental mixtures containing silica fume, fly ash, or slag were evaluated. In the second, one control and three experimental mixtures containing fly ash or slag at a higher water-cementitious material ratio (W/CM) than used in the first program were evaluated. Concretes cured at higher temperatures had higher strengths up to 28 days but lower strengths at 1 year. Permeability decreased with time. Increasing early curing temperatures enabled the achievement of lower long-term permeability for 6 months and beyond at 28 days. Concretes containing a pozzolan or slag had a lower long-term permeability than the control. Adding a pozzolan was more effective in reducing permeability than reducing the W/CM. At cold temperatures, if the specified properties are not achieved, the contractor should change the mix design and/or provide insulating blankets and/or external heat to ensure the desired product.

Authors