What are the M15 and M20 concrete

16.4 Requirements for masonry mortar after suitability test

Requirements for normal masonry mortar

propertyRequirement for
DIN V 20000-412
Mortar group1)/ Mortar class2)
DIN V 18580
Mortar group1)/ Mortar class2)
Dry density [kg / m³]≥ 1500
Compressive strengthlook here
Bond strength3)
[N / mm²]
  • MG I / M 2.5: -
  • MG II / M 5: ≥ 0.04 4)
  • MG IIa / M 10: ≥ 0.08 4)
  • MG III / M 15: ≥ 0.10 4)
  • MG IIIa / M 30: ≥ 0.12 4)
  • MG I / M 1: - / - 5)
  • J MG II / M 2.5: ≥ 0.04 / ≥ 0.10 5)
  • MG IIa / M 5: ≥ 0.08 / ≥ 0.20 5)
  • MG III / M 10: ≥ 0.10 / ≥ 0.255)
  • MG IIIa / M 20: ≥ 0.12 / ≥0.30 5)
Chloride content [mass%]≤ 0.1 based on the dry mass of the mortar
Fire behaviorBuilding material class A 1

1) Mortar groups (MG) according to DIN 1053-1. Standard withdrawn, but as a standard introduced by the building authorities, it can still be used for construction projects that have been approved and are in progress.
2) Mortar classes (M) according to DIN EN 998-2.
3) The bond strength is determined indirectly by testing the adhesive shear strength (characteristic initial shear strength). Instead of a test, the values ​​for the adhesive shear strength can also be assumed in accordance with DIN EN 998-2, Appendix C; for normal masonry mortar, the following value applies: 0.15 N / mm².
4) Testing of the initial shear strength (adhesive shear strength) according to DIN EN 1052-3. Test values ​​are to be multiplied by 1.2 to determine the bond strength.
5) First value: applies to testing the adhesive shear strength according to DIN EN 1052-3; Second value: applies when testing the minimum adhesive shear strength (mean value) according to DIN 18555-5 (standard withdrawn, but still cited in DIN V 18580). Test values ​​are to be multiplied by 1.2 to determine the bond strength.

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Requirements for lightweight masonry mortar

propertyRequirement for
DIN V 20000-412
Mortar group 1) / Mortar class 2)
DIN V 18580
Mortar group 1) / Mortar class 2)
Dry bulk density [kg / m3]
  • LM 21 / M 10: ≤ 700
  • LM 36 / M 10: 700 and ≤ 1000
  • LM 21 / M 10: ≤ 700 3)
  • LM 36 / M 5: ≤ 1000 3)
Thermal conductivity [W / (m · K)]
  • LM 21 / M 10: ≤ 0.18
  • LM 36 / M 10: ≤ 0.27
  • LM 21 / M 5: ≤ 0.18 4)
  • LM 36 / M 5: ≤ 0.27 4)
Compressive strengthlook here
Bond strength 5) [N / mm²]≥ 0,08 6)
  • LM 21 / M 5: ≥ 0.08 7)
  • LM 36 / M 5: ≥ 0.08 7)
Longitudinal expansion module El 8) [N / mm²]
  • LM 21 / M 5: ≥ 2000
  • LM 36 / M 5: ≥ 3000
Transverse expansion module Eq 8[N / mm²]
  • LM 21 / M 5: ≥ 7500
  • LM 36 / M 5: ≥ 15,000
Chloride content [mass%]≤ 0.1 based on the dry mass of the mortar
Fire behaviorBuilding material class A 1

2) Mortar classes (M) according to DIN EN 998-2.

3) If the limit value is adhered to, the requirements for thermal conductivity are deemed to have been met without further proof. With proof, dry bulk densities of up to 1300 kg / m³ are permissible.

4) If the limit value for the dry bulk density of 1300 kg / m³ is exceeded, the thermal conductivity must be verified by testing in accordance with DIN EN 1745.

5) The bond strength is determined indirectly by testing the adhesive shear strength (characteristic initial shear strength). Instead of the test, the values ​​for the adhesive shear strength can also be assumed in accordance with DIN EN 998-2, Appendix C; for lightweight masonry mortar, the value 0.15 N / mm² applies.

6) Test of the initial shear strength (adhesive shear strength) according to DIN EN 1052-3 test values ​​are to be multiplied by 1.2 to determine the bond strength.

7) Value applies when testing the initial shear strength (adhesive shear strength) in accordance with DIN EN 1052-3.

8) Test according to DIN 18555-4 (standard withdrawn, but still cited in DIN V 18580).

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Requirements for thin bed mortar

propertyRequirement for
DIN V 20000-412DIN V 18580
Dry density [kg / m³]≥ 1500≥ 1300
Compressive strengthlook here
Bond strength 1)
[N / mm²]
≥ 0,20 2)≥ 0,20 / ≥ 0,50 3)
Workability time≥ 4 hours
Correctable time≥ 7 minutes
Chloride content [mass%]≤ 0.1 based on the dry mass of the mortar
Fire behaviorBuilding material class A 1

1) The bond strength is determined indirectly by testing the initial shear strength (adhesive shear strength). Instead of the test, the values ​​for the adhesive shear strength can also be assumed in accordance with DIN EN 998-2, Appendix C; for thin bed mortar the value 0.3 N / mm² applies

2) Test of the initial shear strength (adhesive shear strength) according to DIN EN 1052-3 test values ​​are to be multiplied by 1.2 to determine the bond strength

3)