Field evaluation of the impact of environmental conditions on concrete moisture-related shrinkage and coefficient of thermal expansion. (20th November 2019)

• Record Type: Journal Article
• Authors: Mateos, Angel; Harvey, John; Bolander, John; Wu, Rongzong; Paniagua, Julio; Paniagua, Fabian
• Is Part Of: Construction & building materials. Volume 225(2019)
• Page Start: 348
• Page End: 357
• Publication Date: 2019-11-20
• Subjects: BCOA bonded concrete overlay of asphalt -- CSA calcium sulfoaluminate -- CTE coefficient of thermal expansion -- FST field setting time -- RH relative humidity -- VWSG vibrating wire strain gage; Rapid strength concrete -- Drying shrinkage -- Autogenous shrinkage -- Coefficient of thermal expansion -- Thermal deformation; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2019.07.131
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Because of drying, concrete CTE can increase up to 50% versus that of saturated conditions. Modeling with CTE of saturated concrete may highly underestimate thermal effects. Rainfalls, rather than air RH, control re-wetting of concrete in the field. Moisture-related shrinkage in the field cannot be predicted based on air RH alone. The environmental conditions impact portland and CSA cements very differently. Abstract: This study evaluates the impact of the environmental conditions on the moisture-related shrinkage and the coefficient of thermal expansion (CTE) of concrete. The evaluations are based on the strain measured in a series of unrestrained shrinkage prisms during fifteen months. The prisms included four concrete mixtures containing either portland cement or calcium sulfoaluminate cement. The prisms were fabricated in the field and left outdoors so that they were subjected to natural rainfall, sun radiation, and daily and seasonal changes in air temperature and relative humidity (RH). A strain model was used to divide the deformation measured in the prisms into its thermal and moisture-related components. By doing so, the evolution of concrete moisture-related shrinkage and CTE during the fifteen-month period was back-calculated. A strong correlation (R2 = 0.998) existed between the maximum moisture-related shrinkage that was back-calculated in the outdoor prisms and the ultimate moisture-related shrinkage measured in the laboratory under constant temperature and 50 percent air RH. Because of drying, concrete CTE reached values that were up to 50 percent higher than the CTE determined in the laboratory under saturated conditions. Concrete moisture-related shrinkage and CTE systematically decreased after the rainfall events, except when the concrete was already saturated. Rainfalls, rather than air RH, controlled the re-wetting of the concrete in the field.