Elongation at break is the maximum percentage a material can be stretched from its original length before it fractures. Called “breukrek” in Dutch, it is a key mechanical property that indicates how flexible or brittle a material is under tensile stress.
How It Is Measured
Elongation at break is determined through a standardised tensile test:
- A specimen of defined dimensions is clamped in a tensile testing machine
- A steadily increasing pulling force is applied along the specimen’s length
- The machine records the extension of the specimen as the load increases
- The test continues until the specimen fractures
- Elongation at break is calculated as the increase in length divided by the original gauge length, expressed as a percentage
The result is reported according to standards such as ISO 527 for plastics or ISO 6892 for metals.
Why It Matters in Construction
- Sealants and membranes — high elongation at break ensures they can accommodate joint movement without cracking
- Roofing membranes — must stretch over structural movement and thermal expansion without tearing
- Reinforcing steel — sufficient elongation provides ductile warning before failure, essential for structural safety
- Plastics and polymers — pipes, window profiles, and cladding must tolerate impact and flexing
- Coatings — elastic coatings bridge hairline cracks in substrates
A material with high elongation at break is described as ductile; one with low elongation is considered brittle.
Application
Elongation at break is specified in product datasheets for sealants, waterproofing membranes, plastic pipes, reinforcing steel, and protective coatings. Engineers and specifiers use this value to ensure that materials can handle expected movement, settlement, and thermal cycling in a structure without failure.
Related Terms
- Tensile strength
- Ductility
- Elastic modulus
- Yield point
- Strain
More guides and plans available at fredsdiyplans.com