Influence of cement type and temperature on the rate of corrosion of steel in concrete exposed to carbonation

This paper presents the results of a laboratory investigation on the influence of cement type and temperature on the rate of corrosion of steel in concrete exposed to accelerated carbonation (15% carbon dioxide [CO2] concentration). In this study, reinforced concrete specimens (10 cm by 10 cm by 40 cm) having a water/cement ratio of 0.55, exposed to different temperature conditions (20 degrees C, 30 degrees C, and 40 degrees C) were investigated. Measurement of carbonation depth, void ratio, oxygen permeability, and corrosion rate were performed in the laboratory to assess the influence of cement type and temperature on steel corrosion in concrete. The test results show that concrete containing ordinary Portland cement (OPC) has better corrosion resistance at lower temperatures than blast-furnace slag cement (BFSC). On the other hand, BFSC concrete performs better at higher temperatures (30 degrees C and 40 degrees C), especially when exposed over a longer period of time. In general, corrosion rate in the specimens increased with temperature. This is consistent with the theoretical expectation that corrosion rate increases with temperature. Moreover, it was confirmed that the natural logarithm of total corrosion rate is linearly related to the reciprocal of the absolute temperature, which obeys an Arrhenius relationship with temperature.