Analysis and Estimation of Service Life of Corrosion Prevention Materials Using Diffusion, Resistivity and Accelerated Curing for New Bridge Structures - Volume 2: Accelerated Curing of Concrete with High Volume Pozzolans (Resistivity, Diffusivity and Com

摘要

The investigation presents results of the temperature effect via accelerated curing on durability properties (resistivity and diffusivity) and compressive strength of concrete with pozzolans or slag and the effect of these admixtures on microstructure and chemical compositions of concrete pore solution. Temperature dependence of electrical resistivity and chloride diffusivity was studied by dynamic temperature tests in the case of resistivity and by testing chloride migration coefficient (D(sub nssm)) at multiple temperatures on specimens of the same composition. For both type of tests, mature specimens were used (older than one year). Accelerated curing regimes involved curing concrete specimens in 35 degrees C lime water for different periods of time. Compressive strength test, resistivity measurement, bulk diffusion (D(sub app)), and rapid chloride migration (RMC) tests were performed. Additionally, a leaching method was used to measure pH and conductivity of concrete pore solution. Based on the results, general normalization equations were developed to describe the temperature effect on resistivity and diffusivity of concrete. The accelerated curing regime's were found to increase the compressive strength and resistance to chloride ion penetration in the short and long term. With the developed correlation between resistivity and migration coefficients, it is possible to employ the resistivity measurement as an alternative of the RCM test to evaluate resistance of chloride ion penetration of concrete. Bulk diffusion values were also correlated to resistivity values for the different mixtures. Pozzolanic admixtures were found to decrease both pH and conductivity of concrete pore solution as the replacement ratio increased. Moreover, the migration coefficients were found to be greatly correlated to the microstructure properties of concrete, such as porosity, formation factor, and tortuosity.