The reduction of greenhouse gas is one of the central challenges in science and technology.Due to the huge share of total CO2-emissions caused by the production of Portland cement clinker, strategies for CO2-reduction in the concrete industry are needed.Most often the CO2-reduction is accomplished by the substitution of cement through other reactive or non-reactive materials.In order to ensure a minimum technical performance for a certain application different concrete mix optimization strategies are conceivable.One central issue is to find out which of the numerous concrete mixes is suitable for a specific purpose.An important drawback of almost all COt-reduced concretes is that the technical performance is achieved by the use of clearly defined high quality raw materials.In many cases, an optimization of the particle size distribution and other aggregates properties (e.g.particle shape, organic content) cannot be realized because locally available materials have to be used due to economic reasons.Moreover, different qualities of cement, SCMs (supplementary cementitious materials) or fillers have to be coped with.