Risk of environmental contamination arising from concrete structures, Part I: CO2 emission

The present study concerns the CO 2 emission in the process of cement manufacture. Information on raw materials, energy source and oxide composition was achieved from Korean major six manufacturers. As a result, it was found that the energy efficiency for kilning and control for a loss of CaO in cement manufacture are key factors to emission of CO 2 . The variation in the amount of coal in the process of kilning accounted for about 30 kg for one tonne of cement, as being equivalent to 70 kg CO 2 /tonne-cem. Simultaneously, the loss of CaO in refinement of raw materials is crucial in reducing the CO 2 emission. The loss of CaO in the cement production was in the range of 9–24 kg for one tonne of cement, which may impose unnecessary energy of coal in kilning and a further decomposition of CaCO 3 to CaO and CO 2 . Substantially, it can be said that energy control for high efficiency of coal in the kilning process and control for a loss of CaO may reduce several hundreds kg CO 2 /tonne-cem, compared to 729–911 kg CO 2 /tonne-cem in the cement production. Alternatively, the use of pozzolanic material for Portland cement can reduce the CO 2 emission. 30% PFA and 60% GGBS in a concrete mix reduced CO 2 emitted for a given mix about 28.9 and 49.6% respectively, compared to Portland cement.