🏗️ Testing machines for compressive strength testing of concrete — PN-EN 12390-4

Construction PN-EN 12390-4

Overview

THE SCOPE FROM THE PKN CATALOGUE CARD, IN FULL: "This document specifies requirements for the performance of testing machines used for determining the compressive strength of concrete specimens in accordance with EN 12390-3 or cores in accordance with EN 12504-1. Other additional or different requirements may apply for different applications."

THE SECOND SENTENCE MATTERS MORE THAN IT LOOKS. "Other additional or different requirements may apply for different applications" means that meeting this standard is not automatically sufficient for every test carried out on the same machine. A press conforming to PN-EN 12390-4 is fit for compressing concrete specimens and cores; using it for other tests — for instance for compressing other materials, or for tests governed by separate requirements — calls for checking the requirements of that test, not for citing this document.

WHY A MACHINE HAS ITS OWN REQUIREMENTS. The result of a strength test depends on three things: on the concrete, on the geometry of the specimen and on the machine. The geometry is covered by PN-EN 12390-1 (a separate entry in this knowledge base), the making and curing of specimens by PN-EN 12390-2, the test itself by PN-EN 12390-3, and the machine by this very standard. Keeping them apart allows a laboratory to determine where the cause of an unexpected result lies: in the material, in the preparation or in the apparatus.

WHAT DECIDES THE CONFORMITY OF A MACHINE. Not the force range alone, although that is usually quoted first. The correctness of the result is also governed by the uniformity of the pressure distribution over the specimen surface, the stiffness of the frame, the flatness and mutual parallelism of the platens, the stability of the loading rate and the accuracy of the force indication. A machine of the right force range but with platens deviating from parallelism loads the specimen eccentrically and understates the result — and, just as with an out-of-tolerance specimen, this cannot be seen from the figure alone.

THE CHANGE OF EDITION IN 2025. The card of PN-EN 12390-4:2020-03 in the Polish version gives the "Date of withdrawal" row as 26-08-2025 and "Superseded by" as PN-EN 12390-4:2025-08 — the English version. Laboratory practice in many places still rests on the 2020 edition, because that one was available in Polish. A reference to "PN-EN 12390-4" without a year does not settle which edition is meant, and since August 2025 the Polish edition has been withdrawn.

WHAT WE DO NOT GIVE. We do not have the text of the standard — PKN supplies it for a fee (19 pages, TC 274, ICS 91.100.30). We therefore GIVE NO VALUES: neither the permissible deviations of flatness and parallelism of the platens, nor the required accuracy of force indication, nor the range of loading rate. These values are the subject of the standard and changed between editions — quoting them from memory would be a claim about a document we have not read.

Method principle

Compressive strength is determined by loading a specimen to failure and dividing the failure load by the cross-sectional area. The result is reliable only when the load is axial and uniform, rises at a controlled rate, and the force indication is accurate. The standard therefore specifies requirements for the machine as a whole — its frame, platens, drive and force-measuring system — separately from the requirements for the specimen and separately from the procedure of the test itself.

Applications

• Qualification and periodic checking of testing presses in concrete laboratories
• Compressive strength testing of concrete specimens (to EN 12390-3) and of drilled cores (to EN 12504-1)
• Purchasing specification for a testing machine
• Investigating the causes of results departing from expectation — separating the influence of the machine from that of the specimen

Key parameters

Standard

Standard number

PN-EN 12390-4:2025-08 (wersja angielska; wprowadza EN 12390-4:2025 [IDT])

Title (PL)

Badania betonu -- Część 4: Wytrzymałość na ściskanie -- Wymagania dotyczące maszyn wytrzymałościowych

Title (EN)

Testing hardened concrete — Part 4: Compressive strength — Specification for testing machines

Step-by-step procedure

1. Establish what the machine is to be used for

   This standard covers the compression of concrete specimens and cores. For other applications additional or different requirements may apply — the scope says so plainly.

2. Verify the conformity of the machine

   The requirements cover the frame, the platens, the drive and the force-measuring system. THE VALUES ARE NOT GIVEN HERE — they are in the text of the standard.

3. Inspect the platens

   Flatness and parallelism. A machine of the right force range but with deviating platens loads the specimen eccentrically and systematically understates the result.

4. Calibrate the force-measuring system

   A current certificate. Constructional conformity with the standard does not prove the correctness of the indications of a particular item.

5. Set the loading rate

   The rate affects the result — loading too fast overstates the strength. The permissible range is in the test standard and in this one.

6. Record in the report

   Give the identification of the machine, the calibration certificate and the full designation of the standard with its year — since August 2025 the 2020 Polish edition has been withdrawn.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• A concrete specimen fails abruptly, throwing off fragments — a guard around the working space and eye protection are required
• Presses for concrete operate with forces that destroy structural specimens — working with the guard open is not permissible
• TECHNICAL NOTE: a deviation of the platens from parallelism understates the result without leaving any trace in the figure itself — only periodic inspection of the machine geometry detects it

Frequently asked questions