## 3 Results and Discussion
### Economic Application of Optimization of Concrete Dosages to a Real Building  
Three different optimization proposals were analysed considering the strength results and the above considerations of the technical-economical aptitude for each one: (A) intermediate reduction of cement volume (first step of cement reduction); (B) extreme optimization  
Figure 6: Results for the compressive strength of recycled concrete and normal concrete (RC30). by cement volume reduction (both W\({}_{\rm ef}\)/C ratio and cement volume optimization to the standards limitations); and option (C) recycled concrete proposal. Table 6 shows a list of the detailed measurements and concrete strengths of all the elements that make up the type of building described in Figure 2. Additionally, this table shows the estimated costs for the mixtures in current conditions, and the final costs and savings for the three new proposals. * Conventional concrete proposals. The manufacturing costs (only for concrete material) in the type of structure for the current concrete dosages were estimated at EUR 22,309.6, corresponding to a unit per built surface cost of EUR 25.1/m\({}^{2}\). Meanwhile, the costs estimated in Option A (medium optimization) were EUR 19,743.7, i.e., a saving of EUR 2565.9 or an 11.5% reduction in the concrete costs for an alternative with similar strength and functional capabilities. In the same way, the most extreme optimization (Option B) could achieve savings of around 17%, with a total concrete cost of EUR 18,498.1, also for the strength requirements of each element type. However, this extreme optimization requires in-depth research to analyse the functional adaptation of these concrete mixtures to the specific manufacturing process. In any event, these additional experiments are wholly justified by the opportunity of high savings relative to the cost of the current dosages. These conclusions demonstrate that accurate control of the dosages, and primarily of the initial moisture state of aggregates that allow for real-time control of the W\({}_{\rm ef}\)/C parameter, could result in a substantial reduction in the costs of concrete production and help achieve highly homogenous elements. * Recycled concrete proposal. Regarding the recycled alternative (Option C), the total concrete costs for the proposed building were estimated at EUR 20,915.2, a reduction of 6.25% on the total costs. At first sight, this cost is higher than the two cement reduction proposals analysed above, with this comparison making conventional concrete seem better than the recycled concrete proposal. However, once the management costs of recycled aggregates are considered in the economic balance, the recycled alternative emerges as a highly competitive alternative, since the total saving rises from EUR \(-\)1395.0 to EUR \(-\)3963.5, thus being the alternative with highest saving of all the proposals, yielding a reduction of 17.8% over the actual costs. Consequently, this analysis demonstrates that, in addition to being a perfectly feasible solution in strength terms, recycled concrete represents a highly interesting alternative due to the total savings generated in a company's global economic balance. Thus, the technical-economic opportunity of RAC may involve similar and even higher savings than performing high optimization of the W\({}_{\rm ef}\)/C ratio and the cement volume in the dosages.