What is the difference between R3 and R4 mortar?

Repair mortars are used in concrete repair and reconstruction works. The UNE-EN 1504-3 standard “defines and classifies repair mortars according to their technical performance and uses”. Furthermore, it differentiates four classes of repair mortars: Class R1 or lower strength, Class R2, Class R3 and Class R4. In this article, we will focus on the difference between R3 and R4 mortars.

Each one has different values of compressive strength, adhesion, elastic modulus… The classification of a mortar of any type does not indicate a higher or lower quality, but rather that the mortar meets the minimum requirements.

A concrete structure has to be repaired with a mortar that is as compatible as possible with the concrete to be repaired, suitable for the different needs that exist when repairing it and its subsequent commissioning.

What are the differences between R3 and R4 Repair Mortars?

Class R3 mortars have medium-high strengths and medium modulus of elasticity and are suitable for repairing old and/or medium-high strength concrete. Class R4 mortars, on the other hand, are developed for high strengths and higher modulus of elasticity and are suitable for repairing modern and/or high strength concrete structures.

Use in structural repairs: mortars R3 and R4

Both types of mortar are suitable for concrete repairs, either for surface damage or when the reinforced concrete is damaged from the inside affecting the reinforcement.

Structural mortar: R3

This type of mortar is suitable for all types of reinforced concrete structures, where the concrete has to be rebuilt and especially in medium-high performance concrete. It allows restoring the structural and resistant capacity that it had before.

Medium-high strength and medium modulus

The most characteristic values of an R3 type mortar are compressive strength greater than 25 MPa, 1.5 N/mm2 minimum adhesion to the substrate and more than 15 GPa modulus of elasticity. Under normal conditions, the higher the compressive strength, the higher the modulus of elasticity of the repair mortar and, therefore, the higher the stiffness.

The use of Class R3 mortars in medium-strength concrete guarantees the durability of the repair, avoiding medium and long-term problems in the repaired areas due to cracking or loss of adherence due to thermal expansion.

Concrete Repairs of some age

PROPAM® REPAR 30 and PROPAM® REPAR 910 R are the products recommended by our experts. Among their great advantages is their ease of application during the restoration of the concrete to its original specified form and function, by hand application or spraying in the case of PROPAM® REPAR 30, or manual application in the case of fast-setting PROPAM® REPAR 910 R .

Structural mortar: type R4

Class R4 repair mortars are designed for the structural repair of concrete. This type of high strength mortar is suitable for all types of reinforced concrete structures where the concrete has to be rebuilt.

High resistance

Class R4 has a compressive strength of over 45 MPa, 2 N/mm2 adhesion and 20 GPa modulus of elasticity.

Concrete Repairs

In the case of having to make concrete repairs with R4 class mortars, any of these products will help us to achieve a perfect and long-lasting result:

• PROPAM® REPAR 40 sprayable for structural repairs.
• PROPAM® REPAR TECHNO manual application and fast setting for structural and quick repairs of medium sized surfaces.
• PROPAM® REPAR TECHNO 40 sprayable for structural repairs.
• PROPAM® REPAR TECHNO FLUID flowable mortar for structural repairs by pouring.

The enormous advantage that the mortars of the PROPAM® REPAR TECHNO family have over others is the execution of the structural repair with a single product and in a single step, in such a way that we can carry out the repair with one coat and that’s it. This range of products complies with the requirements of EN 1504-3 (Class R4), EN 1504-7 (reinforcement protection) and EN 1504-2 (concrete protection).