Concrete Compression Testing: ASTM C39 vs EN 12390-3 Guide

Why Concrete Compression Testing Matters

The compressive strength of concrete is its most fundamental mechanical property. It determines the structural capacity of columns, beams, slabs, and foundations. Compression testing is performed during mix design, quality control of fresh concrete deliveries, and assessment of hardened structures.

Two standards dominate the global market: ASTM C39 (widely used in the Americas) and EN 12390-3 (the European standard). Understanding the differences between them is critical when specifying testing equipment or operating in multiple markets.

ASTM C39 — Overview

ASTM C39 specifies the test method for compressive strength of cylindrical concrete specimens. Key features:

• Specimen type: Cylinders — standard sizes 100×200 mm and 150×300 mm.
• Capping: Specimens must be capped with sulfur compound or neoprene pads to ensure flat, parallel ends.
• Loading rate: 0.14 to 0.34 MPa/s (20 to 50 psi/s).
• Machine class: Class B accuracy (±1% of applied load) required.
• Result: Expressed in psi or MPa.

EN 12390-3 — Overview

EN 12390-3 specifies the test method for compressive strength of test specimens (part of the EN 12390 series). Key features:

• Specimen types: Both cubes (100 mm, 150 mm, 200 mm) and cylinders (Ø150×300 mm).
• Capping / grinding: Cube faces are cast against steel molds and require less preparation than cylinders.
• Loading rate: 0.6 ± 0.2 MPa/s (constant stress rate).
• Machine class: Class 1 (EN 12390-4) — ±1% accuracy from 10% of capacity.
• Result: Expressed in MPa; used to determine characteristic strength (fck).

Key Differences at a Glance

Choosing a Concrete Compression Testing Machine

Modern compression testing presses are designed to operate in both ASTM and EN modes. When evaluating a machine, check:

• Capacity: 2000 kN is standard for most lab applications; 3000 kN for high-strength concrete or larger specimens.
• Dual-standard mode: The machine should allow switching between ASTM C39 and EN 12390 loading rates from the control panel.
• Platens: Upper platen must self-seat (spherically seated) to apply uniform load. EN 12390-4 specifies platen diameter requirements per specimen size.
• Calibration: Machine must be calibrated at regular intervals (typically annually) using a certified proving ring or load cell.
• Data output: Look for machines with automatic peak load detection, load-displacement curves, and CSV/PDF export.

Practical Notes for Laboratories

If your laboratory operates under Turkish standards (TS EN 12390), the EN loading rate (0.6 MPa/s) applies. Turkish construction projects typically use 150 mm cubes as standard specimens. Elipslab's compression testers are calibrated and certified to EN 12390-4 Class 1 from 10% of capacity, ensuring traceability.

For export projects or international contracts specifying ASTM C39, verify that your machine can switch to the slower loading rate (0.14–0.34 MPa/s) and that you have the appropriate cylindrical specimen molds and capping equipment.