*Numerical Example*

It is necessary to design the concrete class C 40/50 composition with compressive strength at a 1 day of not less than 30% 28 of the daily strength with the slump Sl = 13 cm when using composite cement with Sssa = 350 m2/kg and PFM1 0.7% of the mass of cement. Materials: granite crushed stone fractions 5–20 mm with true density (*ρcs*) −2720 kg/m3 and bulk density (*ρbcs*) −1350 kg/m3, sand with true density (*ρs*) −2650 kg/m3.


$$\text{Cs} = \frac{1000}{\alpha \frac{\upsilon\_{cs}^{\text{II}}}{\rho\_{hcs}} + \frac{1}{\rho\_{cs}}} = \frac{1000}{1.375 \frac{0.5}{1.35} + \frac{1}{2.72}} = 1140 \text{ kg/m}^3\text{s}$$

where *α*—coefficient of displacement of coarse aggregate grains,

*Vcsp*—the crushed stone intergranular voids.

$$\Delta S = \left( 1000 - \left( \frac{\text{C}}{\rho\_{\text{c}}} + W + \frac{\text{C}s}{\rho\_{\text{c}s}} \right) \right) \rho\_{\text{s}} = \left( 1000 - \left( \frac{466}{3.1} + 145 + \frac{1140}{2.72} \right) \right) \times 2.65 = 757 \text{ kg/m}^3. \text{ J}$$

Calculated composition of concrete, kg/m3: *C* = 466 kg/m3, *W* = 145 kg/m3,

*Cs* = 1140 kg/m3, *<sup>S</sup>* = 757 kg/m3, PFM1 = 466 × 0.007 = 3.26 kg/m3, (PG = 0.0004*<sup>C</sup>* <sup>=</sup> 0.18 kg/m3, SP = 0.0066*C* = 3.07 kg/m3).

#### **4. Conclusions**


**Author Contributions:** Conceptualization, L.D. and V.Z.; methodology, R.M.; software, V.Z.; validation, V.M. and R.M.; formal analysis, L.D.; investigation, R.M.; resources, R.M.; data curation, V.Z.; writing—original draft preparation, V.M.; writing—review and editing, L.D.; visualization, V.Z.; supervision, L.D.; project administration, R.M.; funding acquisition, R.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** In this section, you can acknowledge any support given which is not covered by the author contribution or funding sections. This may include administrative and technical support, or donations in kind (e.g., materials used for experiments). The publication cost of this paper was covered with funds from the Polish National Agency for Academic Exchange (NAWA): "MATBUD'2023-Developing international scientific cooperation in the field of building materials engineering" BPI/WTP/2021/1/00002, MATBUD'2023.

**Conflicts of Interest:** The authors declare no conflict of interest.
