DRYING SHRINKAGE STRAIN AND PORE SIZE DISTRIBUTION OF CONCRETE CURED AT HIGH TEMPERATURE

Abstract

It is known that the drying shrinkage strain of concrete is affected by the material, mix proportion of concrete, environmental conditions such as ambient temperature and humidity. And the temperature history at curing also affects. This paper shows the effect of temperature history during curing on drying shrinkage strain and pore size distribution of concrete. Dry shrinkage strain, moisture loss amount and pore size distribution of concrete cured under various temperature histories were measured. As a result, the longer curing at higher temperature, the drying shrinkage strain of concrete decreases, but the moisture loss of concrete increases. As concrete cured at high temperature, the volume of fine pores with diameter of 6nm or less decrease, and the pore volume with diameter of 50nm to 100nm increases. So, concrete cured at high temperature becomes coarse pore structure. There is a correlation between pore volume diameters of 6nm or less and dry shrinkage strain. On the other hand, there is a negative correlation between the pore volume of 50nm to 100nm in diameter and drying shrinkage strain. For those reason, although moisture loss of concrete cured at high temperature becomes increases, drying shrinkage strain becomes small. Therefore, the progress of carbonation of concrete cured at high temperature becomes faster.