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CONCRETE TECHNOLOGY46 CPI %u2013 Concrete Plant International %u2013 5 | 2025 www.cpi-worldwide.comthat the practical guideline values for concrete without admixtures, which range slightly higher from 190 to 215 l/m%u00b3, fit well within the consistency class F3. Depending on the effectiveness or efficiency of the plasticizing admixture, the water content may be reduced further. For example, with a conventional admixture based on polycondensates (standard plasticizers), approximately 15 l/m%u00b3 can be saved, and with a standard PCE plasticizer (FM), the water content can be reduced by about 30 l/m%u00b3 while maintaining comparable workability. Novel plasticizer technologies even allow a reduction in water content of up to 60 l/m%u00b3 with comparable workability [16].6 Estimating minimum water contentBased on the zero-consistency value (WNullk,38cm) discussed in Section 4 and the guideline values for possible water content reductions when using plasticizing admixtures, the minimum possible water content of a specific concrete mix can be estimated. Below this minimum water content, effective liquefaction of the fresh concrete is not possible, even with admixtures. This minimum water content depends in particular on the grain composition of the fine and coarse aggregates (see Section 3).Figure 7 shows the determined zero-consistency values (WNullk,38cm) of three concrete mixes with a constant cement content of 340 kg/m%u00b3, with varying fine aggregate types. It is evident that the WNullk,38cm values vary depending on the fine aggregate used. For example, concrete with Sand S3 has a WNullk,38cm value of 185 l/m%u00b3, while concrete Z3-340-N (with Sand S4) shows a WNullk,38cm value of 201 l/m%u00b3.To achieve a slump flow diameter of 38 cm, an additional 16 l/m%u00b3 of water is required when using Sand S4. This increase is mainly due to the higher fine particle content (see Table 1). As a result of the increased specific surface area, significantly more water is adhesively bound to the surface of Sand S4. This water is no longer available for the effective paste content and thus does not contribute to the liquefaction of the fresh concrete. Considering the guideline values described in Section 5 for possible water reduction with different types of plasticizing admixtures, it becomes possible to estimate the Fig. 6: Guideline values for possible reductions in water content in fresh concrete when using different types of plasticizing admixtures (adapted from [15]).Fig. 7: Water content required to achieve a slump flow diameter of 38 cm without plasticizing admixtures (zero-consistency - WNullk,38cm) depending on the fine aggregate used, along with the estimated possible water reduction when using plasticizing admixtures.