Drying and shrinkage of massive concrete wall segments—3 years experiment and analytical observations

This paper presents 3 years lasting large scale experiment focusing on simultaneous measurements of drying profiles and shrinkage on massive concrete wall segments considering size effect. Three large specimens with thickness 20, 40 and 80 were accompanied by group of small specimens in order to measure additional parameters. Specimens were made from the same concrete mixture and placed in the same environment in the laboratory. Typical concrete mixture was used having water cement ratio 0.5 and average 28-days compressive strength 55 MPa. Pore relative humidity was measured in different depths using embedded plastic tubes and moisture meter, shrinkage (or swelling) strain was measured by embedded vibrating wire strain gauges. Special attention is paid and comments are stated to initial swelling up to 80 μm/m and to observed size effects in drying and shrinkage. Extensive data collected during this experiment were compared with results of various numerical models for shrinkage of concrete and with results of models for moisture transport in concrete. Discussion on the predictive capability of these models is provided. Calculation of apparent shrinkage from measured drying profiles of the wall segments using shrinkage point model is carried out and compared with measured shrinkage as well.