Innovative hybrid fiber-reinforced shotcrete for thin repairing overlays – long term mechanical and structural characteristics

  • 1 Institute of Mechanics, Bulgarian Academy of Science, Sofia, Bulgaria


Solvay Sodi JSC, Devnya, Bulgaria, is the biggest calcinated soda production plant in Europe. It is built in 1974 and it works in three-shift production regime up to present days. The exploitation environment is highly influenced by numerous factors, act ing corrosively on main reinforced concrete structures – active atmospheric processes (in continental type moderate climate), sea water born chlorideaerosols, as well chemical attack caused by carbon dioxide and nitric acid, presented in the air in form of evaporation. The most reinforced concrete structures need urgent remedial measures to restore the load-bearing capacity of its components.
The “light soda” silos are reinforced concrete facilities (cylindrical shells) which repair has to be executed dur ing continuous production process. The options for repair of these structures and restoration of their load bearing ability by specially designed innovative high-tech hybrid reinforced sprayed concrete, containing capillary crystalline admixture, are discussed in the report.
It is well known that two basic methods of shotcrete exist – “dry” and “wet” ones.
The report discusses the main advantages of the specially designed innovative hybrid fiber-reinforced “wet” shotcrete for thin repairing overlays, compared to industrially made “dry” one. By purposeful using of standard and direct physical test methods the basic long -term mechanical and structural characteristics of two composites are presented and discussed. The effectiveness of the proposed “wet” method is based to real possibilities to involve in concrete mix design different chemical innovative admixtures – ultra high range water reducing (HRWRA), shrinkage compensating (ShCA), internal crystallization one, etc. The mechanical properties of “wet” one dramatically exceeded respective ones of the “dry” one. The mechanical test results fully correspond to the respective long -term structural characteristics, obtained by using of X-Ray, DTA, SEM and BET-methods.
It could be concluded that the innovative hybrid fiber-reinforced “wet” shotcrete is preferable for high-performance thin repairing overlays
for structural strengthening of damaged concrete structures.



  1. Naidenov V., Tzv. Georgiev, Innovative design for repair of corrected industrial reinforced concrete structures of light soda silos - SOLVAY SODI AD, DEVNYA, Proc. of International Scientific Congress “Machines. Technologies. Materials”, 09- 12.09.2020, Varna, Year IV, Issue 2(17), ISSN 2535-0021 (PRINT), ISSN 2535-003X, (45-49)
  2. Naidenov V., An Innovative Approach for Repairing of Corroded Reinforced Concrete Industrial Structures in Aggressive Environment by High-tech Hybrid Reinforced Sprayed Concrete with Capillary Crystalline Admixture, “Machines, Technologies, Materials” (MTM), Year XIII, Issue 6/2019, ISSN PRINT 1313-0226, (259-262).

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