INVESTIGATION OF DRYING SHRINKAGE PREDICTION OF CONCRETE IN REAL ENVIRONMENT

Abstract

In order to control shrinkage cracks of concrete structures more accurately, it is required to predict shrinkage strain of concrete member size. However, predictions under real environments where different specimen size and temperature and humidity change have not been fully investigated. In this study, Ordinary Portland cement and blast furnace cement type B concrete with different volume to surface ratio were studied in this research. The samples were investigated the relative humidity and shrinkage strain inside the concrete under 20℃ environment under 60％RH condition and an indoor exposure where only temperature and humidity change while not affected by sunlight, rainfall, wind, etc. As a result, in the range of volume to surface ratio of 100mm or less, the test specimens in the indoor exposure environment had a slower evolution of shrinkage strain compared to the one of 20℃ environment under 60％RH condition and the shrinkage strain in the indoor exposure environment was about 5 to 15％ smaller at the drying period of 364 days than in the environment under the condition of 60％RH at 20℃. Shrinkage strain in the indoor exposure environment were about 5 to 15％ smaller than that of 20℃ environment under 60％RH condition in the drying period of 364 days. Moreover, it was confirmed that the behavior of shrinkage strain in a real environment where temperature and humidity change can be predicted by applying the monthly average value or annual average value of the relative humidity around the specimen to the existing prediction formula.