3.2.3. CO2 Emissions from Concrete Made of CEM II/C-M and CEM VI Cement

The concrete emission level was calculated based on the level of CO2 emissions from 1 Mg of cement (Table 2). The results are presented in Table 9. The obtained CO2 emission levels per 1 m3 of concrete are very low (Table 2). When converting the level of CO2 emission into 1 MPa of compressive strength, it can be observed that an important factor is the w/c ratio in concrete. With a lower w/c ratio (0.35), the strength levels are much higher and the difference in the level of the obtained compressive strength depending on the composition of the cement starts to fade. The CO2 emission level per 1 MPa is significantly reduced also, e.g., in the case of CEM II/C-M (30V-10LL) cement from 4.9 kg (w/c = 0.60) to 2.3 kg (w/c = 0.35). Considering the compressive strength after 90 days, CO2 emissions are lower, on average by about 0.7 kg at w/c = 0.60 and about 0.2 kg at w/c = 0.35. This is due to the fact that cements with a high content of the main components other than Portland clinker (mainly granulated blast furnace slag and/or fly ash) have a significant strength increment between 28 and 90 days of hardening.

**Table 9.** CO2 emissions from 1 m3 concrete and converted to 1 MPa of 28-day and 90-day concrete compressive strength.

