ISO 4635:2011

Overview

ISO 4635:2011 specifies material and performance requirements for preformed vulcanized rubber joint seals used between concrete paving sections of highways. It covers seals for both new construction and maintenance work but does not set specific seal designs or dimensions - instead it defines general requirements for finished seals (material properties, durability and functional behaviour). The standard is based on experience with chloroprene (CR) and ethylene‑propylene‑diene monomer (EPDM) rubber and emphasizes ozone resistance, dimensional quality, and long‑term performance.

Key topics and technical requirements

• Material and appearance: Seals shall be made of ozone‑resistant rubber and be black in colour; reliance on surface coatings for ozone protection is not permitted.
• Hardness classification: Five IRHD hardness classes (nominal classes 40, 50, 60, 70 and 80) with a maximum hardness variation of ±5 IRHD over a 5 m length.
• Mechanical properties: Specified minimum tensile strength and elongation at break per hardness class (e.g., higher elongation required for softer grades).
• Compression set: Limits at elevated (+70 °C) and low (−25 °C) temperatures to ensure seal recovery after compression.
• Aging and environmental resistance: Accelerated ageing (72 h at 100 °C) limits for changes in hardness, tensile strength and elongation; ozone resistance tested under standard conditions (no cracking).
• Stress relaxation and recovery: Long‑term stress relaxation in compression (100 days at 50 °C) and recovery performance at low and elevated temperatures are specified.
• Effect of water: Volume change limits after immersion (e.g., 0 to +5% after 168 h).
• Protection against over‑extension: Option to include fiber reinforcement with defined activation/break characteristics.
• Functional testing: Optional cold‑climate functional tests and requirements for marking, labelling and storage.

Applications and who uses this standard

ISO 4635:2011 is used by:

• Highway engineers and pavement designers specifying joint seals for new roads and rehabilitation projects.
• Seal manufacturers and compound formulators to develop and certify preformed vulcanized rubber profiles (CR, EPDM).
• Quality inspectors and testing laboratories performing hardness, tensile, compression set, ageing, ozone and water‑effect tests.
• Procurement and public works agencies writing technical specifications for highway joint materials.

Practical benefits include improved watertightness of joints, predictable long‑term performance under traffic and climate exposure, and consistent quality control for highway sealing systems.

Related standards

Normative references include ISO 37 (tensile tests), ISO 48 (IRHD hardness), ISO 188 (accelerated ageing), ISO 815 (compression set), ISO 1431 (ozone testing), ISO 1817 (effect of liquids), ISO 2230 (storage) and ISO 3302‑1 (dimensional tolerances). These referenced standards define the specific test methods used to verify compliance with ISO 4635:2011.