🏗️ Compressive Strength of Concrete

Construction PN-EN 12390-3

Overview

STATUS (as of 28.10.2026). PN-EN 12390-3:2019-07 — Polish version, published 20.07.2020, implements EN 12390-3:2019 [IDT]; it replaced PN-EN 12390-3:2011 together with the corrigendum PN-EN 12390-3:2011/AC:2012. The standard is current — no withdrawal note.

SCOPE AND PRINCIPLE (clauses 1, 4). The standard specifies the determination of the compressive strength of test specimens of hardened concrete. The specimen is loaded to failure in a compression testing machine conforming to PN-EN 12390-4, the maximum load sustained by the specimen is recorded and the strength is calculated.

SPECIMENS (clause 6). The specimen is a cube, cylinder or core meeting the requirements of PN-EN 12350-1 (sampling of fresh concrete), PN-EN 12390-1 (shape and dimensions), PN-EN 12390-2 (making and curing) or PN-EN 12504-1 (cores taken from structures). A specimen with dimensions outside the tolerances of PN-EN 12390-1 is rejected, adjusted or tested according to Annex B; one of the methods of Annex A is used for adjustment. Damaged or honeycombed specimens may be tested, but their condition is recorded in the test report. The standard recommends determining the density before the compressive strength.

MAKING AND CURING SPECIMENS (PN-EN 12390-2, 6.5). The specimen stays in the mould for at least 16 h but not longer than 3 days at (20 ± 5) °C ((25 ± 5) °C in hot climates), protected against shock, vibration and dehydration. After demoulding it is cured until testing in water at (20 ± 2) °C or in a chamber at (20 ± 2) °C and relative humidity of at least 95 % — the standard considers both methods equivalent.

FROM REMOVAL TO TESTING (7.1). The specimen is tested as soon as practicable, but within 10 h of removal from curing. The test facility is at (20 ± 5) °C ((25 ± 5) °C in hot climates); specimens waiting longer than 4 h are protected from moisture loss, e.g. with wet hessian or an impermeable membrane. The load bearing surfaces of cubes are left as moulded; cylinders, cores and adjusted specimens are ground or capped according to Annex A. No packing may be placed between the specimen and the platens other than the auxiliary platens and spacing blocks of PN-EN 12390-4.

LOADING (7.2). A constant rate of loading is chosen within 0.6 ± 0.2 MPa/s. After an initial load not exceeding about 30 % of the failure load, the load is applied without shock and increased at the selected rate ± 10 % until no greater load can be sustained; the maximum load in kN is recorded. For concrete with a cube strength above 80 MPa or below 20 MPa, guidance on the loading rate may be given by provisions valid in the place of use of the concrete.

TYPE OF FAILURE (7.3). Satisfactory failures are shown in Figures 1 (cubes) and 3 (cylinders), unsatisfactory ones in Figures 2 and 4; an unsatisfactory failure is recorded with the letter of the closest pattern. For cylinders, failure of the capping before the concrete is an unsatisfactory failure.

RESULT (clause 8). fc = F / Ac, where F — maximum load in N, Ac — cross-sectional area calculated from the designated size of the specimen (PN-EN 12390-1), or, when tested according to Annex B, from measured dimensions; the result in MPa (N/mm²) to the nearest 0.1 MPa. The standard gives the strength of a single specimen — the rules for combining results and assessing the conformity of concrete are set by other documents.

WHAT WE DO NOT GIVE HERE. The methods of adjusting the load bearing surfaces (Annex A), the procedure for specimens outside the dimensional tolerances (Annex B) and the precision data (clause 10) — we only know their titles. We do not reproduce the requirements for classes of testing machines (PN-EN 12390-4); the current edition of that standard (2025) introduced two classes of machines and a reference to EN ISO 7500-1.

Method principle

The concrete specimen — cube, cylinder or core — is removed from curing, excess moisture is wiped off and it is centred on the lower platen of a compression testing machine conforming to PN-EN 12390-4, a cube so that the load acts perpendicularly to the direction of casting. The specimen is loaded without shock at a constant rate chosen from 0.6 ± 0.2 MPa/s until it can sustain no greater load.

The compressive strength fc = F / Ac is the maximum load divided by the cross-sectional area calculated from the designated size of the specimen. The result is given for each specimen to the nearest 0.1 MPa, together with an assessment of the type of failure according to the figures in the standard.

Applications

• Compressive strength of concrete specimens made and cured according to PN-EN 12390-2 (cubes and cylinders)
• Compressive strength of cores taken from structures according to PN-EN 12504-1
• Testing of damaged specimens or specimens outside the dimensional tolerances — with a description of their condition or according to Annex B of the standard

Key parameters

Standard

Standard number

PN-EN 12390-3:2019-07

Title (PL)

Badania betonu — Część 3: Wytrzymałość na ściskanie próbek do badań

Title (EN)

Testing hardened concrete — Part 3: Compressive strength of test specimens

Step-by-step procedure

1. Making and curing specimens

   Specimens are made according to PN-EN 12390-2 from concrete sampled according to PN-EN 12350-1; in the mould for at least 16 h and not longer than 3 days at (20 ± 5) °C, protected against shock, vibration and dehydration; after demoulding water at (20 ± 2) °C or a chamber at (20 ± 2) °C and humidity of at least 95 % until testing.

   🌡 Temperature: 20 ± 2 °C

2. Checking the specimens

   A specimen with dimensions outside the tolerances of PN-EN 12390-1 — reject, adjust by a method of Annex A or test according to Annex B. Record damage and honeycombing in the test report (clause 6). The standard recommends determining the density first.

3. Preparing load bearing surfaces

   Cubes — surfaces as moulded, without treatment; cylinders, cores and adjusted specimens — grinding or capping according to Annex A. No packing between the specimen and the platens other than the auxiliary platens and spacing blocks of PN-EN 12390-4 (7.1).

4. Removal from curing and waiting

   Test as soon as practicable, within 10 h of removal; test facility (20 ± 5) °C, in hot climates (25 ± 5) °C. Protect specimens waiting longer than 4 h from moisture loss, e.g. with wet hessian or an impermeable membrane (7.1).

   🌡 Temperature: 20 ± 5 °C

5. Positioning in the machine

   Clean the machine platens and remove loose grit from the specimen surfaces, wipe off excess moisture. Position a cube so that the load acts perpendicularly to the direction of casting; in a two-column machine the trowelled surface is not in contact with the platens and faces a column. Centre to 1 % of the designated size; align auxiliary platens with the specimen (7.1).

6. Loading to failure

   Choose a constant rate from 0.6 ± 0.2 MPa/s. After an initial load not exceeding about 30 % of the failure load, load without shock at the selected rate ± 10 % until the specimen can sustain no greater load; in a manually controlled machine correct any decrease of the rate before failure. Record the maximum load in kN (7.2).

7. Assessment of the type of failure

   Compare with the figures of the standard: satisfactory — Fig. 1 (cubes) and Fig. 3 (cylinders), unsatisfactory — Figs. 2 and 4; record an unsatisfactory failure with the letter of the closest pattern. Failure of the capping of a cylinder before the concrete is unsatisfactory (7.3).

8. Calculation of the result

   fc = F / Ac; F — maximum load in N, Ac — cross-sectional area in mm² from the designated size (PN-EN 12390-1) or from measurements when tested according to Annex B. Result to the nearest 0.1 MPa (clause 8).

9. Test report

   Required, among others: identification of the specimen, condition on receipt, designated dimensions (or measured — Annex B), method of adjustment, date of test, maximum load in kN, strength to the nearest 0.1 MPa, unsatisfactory failure and its type, deviations, declaration of the person responsible, age of the specimen (if known). Optional: mass, density (PN-EN 12390-7), curing since receipt, test facility temperature, time of test (clause 9).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• The standard contains no safety requirements — rules for working with the compression testing machine are set by the laboratory on the basis of a risk assessment and the machine manufacturer's instructions
• Failure of the specimen may be violent (the standard describes "explosive" failure as satisfactory for cubes) — observe the test from behind the machine guard
• Do not put hands between the machine platens during loading

Frequently asked questions