Normal reinforced concrete ring OD (outer diameter) /ID (inner diameter) = 5500/5100 MM Normal reinforced concrete rings OD/ID = 5500/5100 mm are elements of the individual key segments intended for the assembly of the tunnel ring in the tunnel lining for sealed tunnel lining of underground tunnels.

Reinforced concrete blocks are used as blocks under the index:

  • 55 LAF - flume block (foundation),
  • 55 H pr - normal block right 5100,
  • 55B - key block, designed for reinforced concrete ring with external diameter of 5500 mm and internal diameter of 5100 mm.

The blocks are made of heavy concrete in accordance with GOST 26633. Compressive strength class of concrete is B35 (concrete grade M450).

Frost resistance grade of concrete is F150 according to GOST 10060.0.

Water resistance of concrete is W6 in accordance with GOST 12730.5

Reinforcing steel is used for block reinforcement:

  • working unstressed reinforcement - hot-rolled reinforcing steel of smooth and periodic profile. АI, АIII according to GOST 5781

Steel grade C235 to GOST 27772 is used for embedded parts

Technical specifications

Name of the characteristic

Block mark

55 LAF

55 Н pr



Concrete volume,





Weight, t




The design load-bearing capacity of the lining,


40 t/m2 - vertical uniformly distributed load,

13 t/m2 - horizontal with an elasticity coefficient of the ground of 20 kg/cm2


Materials used in the production of normal reinforced concrete rings OD/ID = 5500/5100 mm:

  1. Reinforcement of class AI, A III round periodic profile;
  2. For embedded parts rolled steel C235;
  3. Crushed stone - a fraction of 5-20mm, strength is not below 1200;
  4. Sand - natural enriched, washed;
  5. Cement - Portland cement CEM 42,5.