Protection of Beams & Concrete Slabs Tecbor® A (R-30 / R-240)

As minimum and maximum thickness were tested depending on the requested REI, we will need a determined number of layers to be installed. The boards will be directly fixed to the concrete with metal impact anchors HIlti DBZ type.

Boards layout will be butt joint with no need of bonding paste. In the case where the gap between joints is bigger than 3 mm, Tecsel® mastic will be needed.

SPALLING EFFECT

This explosion is the violent break of the concrete layers or pieces of the surface of a structural element when exposed to a fast increase of temperatures, as it happens during a fire.

It usually takes place during the first 20 or 30 minutes in a conflagration. Many materials, (for example: permeability, saturation level, size and type of aggregate, presence of breakage and reinforcement); the geometrical shapes (as the section size) and the environment (resistance level, or heating and profile rate), have been factors influencing the splinters during a fire, as it has been identified from the researches.

The main factors which impact on the splinters are: the rate of warning (mainly over 2° or 3°C/minute), permeability of the material, degree of saturation of the pores (mainly over 2 or 3% of the moisture content by weight of the concrete), presence of reinforcement and level of external applied resistance.

Concrete’s low permeability shows a greater tendency to splinter than one with concrete’s average resistance, despite its greater resistance to tension.

This is because greater pressures on the pores are formed during the heating, due to the low permeability of the material. Furthermore, the highest pressure point on the pores happens closer to the surface for concrete.

PROTECTION WITH TECBOR® BOARDS

Fire resistance of concrete structural elements varies according to its density, moisture content, composition, size factors and distance to the shaft edge of the metal framework.

With the calculation methods contained in ENV 1992- 1-2 1955 standard, Eurocode 2 part 1-2 can be designed the concrete structural elements with the required bearing and compartment capacity for normalized thermal action.

Nevertheless, in order to improve the resistance capacity of the concrete, the Tecbor® boards offer a very effective and economic technical solution, increasing the fire resistance of the concrete structural elements.

EUROCODE 2, establishes the possibility of using protection and improvement systems with the corresponding test to determine both the equivalent thickness of the material and its capacity to remain cohesive and consistent with the slab.

CTE in its annex C also collects these specifications.

Tecbor® boards have their corresponding test according to UNE ENV 13381-3: 2004 standard. The equivalent factors in concrete of the Tecbor® boards for different fire resistances have been tested through this test. The thicknesses to be applied are determined according to these factors.

Mercor tecresa® has carried out the study to calculate the minimum thickness of the Tecbor® boards to obtain different critic T at different coating thickness both on slabs.