01519089

Component

The aim of the study was to observe the changes in bulk conductivity of concrete and its moisture content when exposed to freezing and thawing cycles in the presence of deicer salt solutions. To accomplish this goal, it was important to first study the effects of each stimulus separately. This paper summarizes the results of investigations on the influence of changing temperature, saturation level and air content of hardened concrete on its bulk conductivity. All conductivity measurements were performed on specimens prepared from mixtures meeting the requirements of the Indiana Department of Transportation (INDOT) for pavement concrete. It was found that the temperature dependence of the bulk conductivity of concrete closely follows the Arrhenius relationship. Formation factor, defined as the ratio of the pore solution conductivity to the bulk solution conductivity when the sample is saturated, was used to quantify the microstructure of concrete. It is a measure of the volume of the pores and their connectivity. Conductivity measurements were performed on concrete with four different air contents and it was found that the formation factor decreased with increase in the air content. This data was then used to derive a relationship between bulk conductivity of concrete and its air content. On drying, the tortuosity of the conduction path increases resulting in a decrease in the bulk conductivity of concrete. This was verified for concrete with saturation levels ranging between 80% and 100%.

This paper was sponsored by TRB committee AFN30 Durability of Concrete.

01503729

14-5694

English

14p

2014

Transportation Research Board 93rd Annual Meeting

Digital/other

Figures; References; Tables

Air content; Concrete; Freeze thaw tests; Microstructure; Moisture content; Percent saturation; Permeability; Temperature

Indiana Department of Transportation

Highways; Materials; I32: Concrete

Transportation Research Board Annual Meeting 2014 Paper #14-5694

TRIS, TRB, ATRI

Jan 27 2014 3:59PM