Ways to expand the raw material base and reduce material consumption in the production of reactive powder concretes

Introduction. Reactive powder concrete (RPC) characterized by high strength and density falls into the category of concretes having ultra-high physicomechanical properties. NIIZHB specialists developed an RPC production and application technology involving the use of pit-run aggregates, silica fume, and low water demand binders (LWDBs) obtained via intergrinding using a rationally selected raw mixture, which includes portland cement, mineral admixtures, and a chemical modifier. The technology for developing RPCs adopts a higher dispersion degree, with cement as the most finely ground component replaced by silica fume, while the roles of fine and coarse aggregates are played by binder and sand, respectively. This factor ensures a compressive strength of 160-200 MPa at 28 days and a bending tensile strength of 20-30 MPa and greater, depending on concrete composition, hardening conditions, the presence of a micro-reinforcing component, etc. A distinctive feature of RPCs consists in the increased cement binder content (800-1000 kg/m³), leading to a high material consumption of RPCs, as well as reducing economic efficiency.

Aim. To study the feasibility of obtaining RPCs while replacing a certain amount of the clinker component with various mineral admixtures intended to reduce the consumption of the cement component, which is the most energy-intensive and costly component.

Materials and methods. A composite LWDB and various active mineral admixtures (metakaolin; granulated blast-furnace slag) were used as a binder in the production of RPCs.

Results. The paper provides a comparative analysis of the technological properties of concrete mixtures (density and water demand) and the physicomechanical properties of RPCs varying in composition (compressive strength).

Conclusions. It was established that up to half of the cement component used in LWDBs can be replaced by blast furnace slag at a constant silica fume content in the binder (25 %) while maintaining or slightly reducing the concrete strength (up to 5-8 %). In this case, it is possible to save about 300-400 kg of cement per 1 m³ of RPC.

1. Richard P., Cheyrezy M.H. Reactive Powder Concretes with High Ductility and 200-800 MPa Compressive Strength. In: Metha P.K., ed. Concrete Technology Past, Present and Future, Proceedings of the V.M. Malhotra Symposyum ACI SP-144. San Francisco; 1994, p. 507-518.

2. Batrakov V.G., Babaev Sh.T., Bashlykov N.F., Falikman V.R. Binder-based concrete with low water demand. Beton i zhelezobeton [Concrete and reinforced concrete]. 1988;(11):4-6 (in Russian).

3. Bashlykov N.F., Babaev Sh.T., Zubekhin S.A., Serdyuk V.N., Falikman V.R., Yudovich B.E., et al. Hydraulic cement. Patent of Russian Federatiom no. 2096364. Publ. date 20.11.1997 (in Russian).

4. Babaev Sh.T., Bashlykov N.F., Zubehin S.A., Serduk V.N., Serykh R.L., Falikman V.R., et al. Cementitious Materials and Method of Making the Same. Patent USA no 5478391A. Publ. date 26.12.1995 (in Russian).

5. Ioudovitch B.E., Dmitriev A.M., Zoubekhin S.A., Bashlykov N.F., Falikman V.R., Serdyuk V.N. Low-water Requirement Binders as New-generation Cements. In: Proceedings of 10th International Congress on the Chemistry of Cement. Goteborg, Sweden; 1997, Pub. No. 3iii021.

6. Powers T.C. The properties of fresh concrete. New York: John Wiley & Sons; 1968.

7. Falikman V.R., Bashlykov N.F. Low Water Demand Technology for Environmentally Friendly Cements with Low Clinker Content. In: Proceedings of the International RILEM Conference “Advances in Construction Materials Through Science and Engineering”, 5-7 September 2011, Hong Kong, China. RILEM Publications S.A.R.L.; 2011, p. 633-642.

8. Wang K., Zhi G. Evaluating Properties of Blended Cement for Concrete Pavements. Final Report Center of Cement Concrete Pavement Technology. Iowa State University, Ames, IA; 2003.

9. Falikman V.R. Mineral additives in modern concrete technology. In: Conference Proceedings of ICCX Russia - 2020, 01-04 December 2020. St. Petersburg; 2020, p. 12-23 (in Russian).

10. Koval S.V. Development of scientific bases for modifying concrete with polyfunctional additives. Ph.D. Odessa; 2004 (in Russian).

11. Sersale R. Mechanism and Reaction Products of Lime with Pozzlanas and Blast Furnace Slags. In: 20, New Ser.; 1971, p. 5-13.

12. Schroder F.S. Slags and Slag Cement. In: Proceedings of the V International Symposium on the Chemistry of Cement. Tokyo; 1968, p. 206-217.

13. Ginzburg I.G. Portland slag cement as a binder for hydrotechnical concrete. Leningrad: VNIIT; 1971 (in Russian).

14. Kramer V. Influence of chemical composition and physical structure of blast-furnace slag on its activity. In: Fourth International Congress on Cement Chemistry. Moscow: Stroyizdat Publ.; 1964, p. 563-575 (in Russian).

15. Kramer V. Blast furnace slags and slag cements. In: Proceedings of the VI International Congress on the Chemistry of Cements. Moscow: Stroyizdat Publ.; 1964, p. 497-519 (in Russian).

16. Gorshkov V.S., Timashev V.V., Saveliev V.G. Methods of physic-chemical analysis of binders. Moscow: Vysshaya shkola Publ.; 1981 (in Russian).

17. Korotkikh D.N. On the requirements for nano-modifying additives for high-strength cement concrete. Nanotekhnologii v stroitel'stve = Nanobuild. 2009;(2):42-49 (in Russian).