Influence of environment and size on the creep and drying shrinkage of concrete.

Abstract

In literature a lot of studies about the prediction of creep and shrinkage of concrete at constant temperature and relative humidity can be found. However, when a concrete structure is built in reality, temperature and relative humidity of the environment vary with location and seasons of construction. So it can be expected that the "moment of casting concrete" has an influence on the evolution of creep and shrinkage of that concrete. In order to acquire information regarding the problem of " the prediction of creep and shrinkage due to a time-varying climate history" a research program is going on at the University of Ottawa. The following parameters are examined: curing period, storage environment, specimen size and age of loading. Creep and shrinkage testing of two sets of specimens is described. For the size and environment tests, the 89 mm, 152 mm, 254 mm, and 610 mm diameter cylinders were used. All specimens were exposed to the chosen environment after moist curing 3-4 days and typically loaded at 24 days. For the age of loading tests, 89 mm diameter specimens were loaded at concrete ages raging from 3 to 200 days, 152 mm diameter specimens were loaded at concrete age 24 days, 254 mm diameter specimens were loaded at concrete ages raging from 24 to 200 days, and 610 mm diameter specimens were loaded at concrete age 24 days in each of the chosen environment. The environment wereinside Lab (22°C, variable humidity), Tent 22°C and 50 % relative humidity , outside (uncontrolled temperature and humidity) and immersed in water.