Innovative sample design for corrosion rate measurements in carbonated blended concrete

Lowering the clinker content of concrete using SCMs can contribute significantly to reduce the energy consumption for cement production and the CO2 emissions of building materials. Substitution of clinker up to 65% is now possible according to European and Swiss standards. Uncertainty about durability, especially carbonation induced corrosion, is the main factor limiting the practical use of these blended cements. For service life prediction of concrete structures with new, blended cements corrosion rate data are urgently needed because the so called “corrosion propagation stage” might be a significant part of the total service life. Such data so far can be obtained only with very time consuming tests due to the sample size of standard concrete samples and the slow carbonation process. In this paper an innovative experimental setup is presented that overcomes these limitations. The setup consists in miniaturised thin samples with a size of 80 x 80 x 6 mm, thus with an effective carbonation depth of only 3 mm. With this new sample design the corrosion rate of steel in carbonated samples can be studied at any relative humidity. Our preliminary results show that these samples allow any kind of electrochemical measurements can be performed – thus the study of corrosion and related influencing parameters, in homogenous carbonated conditions, is possible within a short time scale.