Production of Portland clinker is inherently associated with CO₂ emissions originating from limestone decomposition, the irreplaceable large-scale source of calcium oxide needed. Besides carbon capture and storage, CO₂ mineralization is the only lever left to reduce these process emissions. CO₂ mineralization is a reversal reaction to clinker production—CO₂ is bound into stable carbonates in an exothermic process. It can be applied in several environmentally and economically favorable ways at different stages of clinker, cement and concrete life cycle. These possibilities are assessed and discussed in this contribution. The results demonstrate that when combined with concrete recycling, the complete circularity of all its constituents, including the process CO₂ emissions from the clinker, can be achieved and the overall related CO₂ intensity significantly reduced.

A non-equilibrium diffusion–reaction model is proposed to describe chloride transport and binding in cementitious materials. A numerical solution for this non-linear transport with reaction problem is obtained using the finite element method. The effective chloride diffusion coefficients and parameters of the chloride binding are determined using the inverse method based on a diffusion–reaction model and experimentally measured chloride concentrations. The investigations are performed for two significantly different cements: ordinary Portland and blast furnace cements. The results are compared with the classical diffusion model and appropriate apparent diffusion coefficients. The role of chloride binding, with respect to the different binding isotherms applied, in the overall transport of chlorides is discussed, along with the applicability of the two models. The proposed work allows the determination of important parameters that influence the longevity of concrete structures. The developed methodology can be extended to include more ions, electrostatic interactions, and activity coefficients for even more accurate estimation of the longevity.

The alternative waste fuels have a significant share in the fuel mix of the cement industry in Poland. The conditions inside cement kilns are favorable enough for environmentally-friendly use of waste fuels. In the article, the authors discuss the current situation concerning the use of alternative fuels in Poland, from difficult beginning in the 1990s to the present time, different kinds of fuels, and the amounts of used fuels. The use of fuels in Poland is presented against the global and EU consumption (including Central European countries and companies). The increased use of waste-derived fuels, from the level of about 1% at the end of the 1990s to the present level of about 70%, allowed for the limitation of waste storage, including avoidance of greenhouse gas emissions and consumption of conventional energy sources; those effects also contributed to the implementation of the sustainable development and circular economy conceptions. The experiences of the cement plants worldwide prove that the use of waste fuels is ecological and economical. The examples showed in the article confirm that cement plants are greatly interested in using waste fuels from waste, as they invest in the infrastructure allowing to store bigger amounts of waste and dose them more efficiently. Thus, the cement industry has become an important element of the country’s energy economy and waste management system.