Crack bridging is the flexible substance that seals cracks in concrete, asphalt and other substrates. It may also be referred to as crack or joint sealant. Both cold- and hot-applied crack bridging materials are commonly used. Asphalt plug joints are a type of crack bridging specifically used to seal movement and expansion joints between sections of roads, bridges, sidewalks and other structures.

Crack bridging aims to seal up the crack and prevent water, chemicals and debris from entering the structure. The seal can lessen the possibility of further cracking and damage.

ACE Laboratories offers several sealant testing options that evaluate the performance of crack bridging substances under specific conditions. These tests are important to the construction industry but may also benefit government agencies and other industries.

The Importance of Testing Crack Bridging

Testing crack bridging substances is important for evaluating the substance’s performance in real-world conditions. ASTM International – an internationally recognized organization committed to determining and setting standards for a wide range of materials, products, systems and services – has developed standards for crack bridging testing that help ensure uniformity and reliability among sealants.

The ASTM-standards testing service ACE Labs offers for crack bridging assess a variety of properties, including a material’s:

  • Softening point
  • Flexibility
  • Ductility
  • Tensile adhesion
  • Extreme temperature tolerance
  • Bond properties
  • Compatibility with asphalt

Testing Methods for Crack Bridging

ACE Laboratories offers a wide range of testing and development services for crack bridging substances.  Some of the most common test methods for asphaltic sealants include the following ASTM international standards:

ASTM D6690

Hot-applied joint and crack sealants are evaluated under ASTM D6690 testing standards. The test methods are designed to evaluate sealant performance under a variety of environmental conditions, including extreme cold and extreme wetness. ASTM D6690 determines the sealant’s:

  • Service temperature range
  • Penetration values
  • Bond properties
  • Asphalt compatibility

ASTM D4402

Because crack bridging is often used on asphalt – and many crack sealant products contain asphalt – ACE Laboratories offers ASTM D4402 asphalt viscosity testing. This test helps illuminate an understanding of asphalt’s behavior under a variety of temperature conditions. ASTM D4402 measures the viscosity of asphalt and bitumen at the specific temperature associated with the process steps of handling, mixing and applying the material.

ASTM D6297

ASTM D6297 is specific to field-molded asphaltic plug joints. Also known as APJs, asphalt plug joints are typically applied at connection points between roads, expressways and bridges. They may also be used in asphalt overlay projects and are appropriate for single-layer and multi-layer application systems. ASTM D6297 describes methods for evaluating an APJ’s properties of:

  • Tensile adhesion
  • Ductility
  • Resilience
  • Flexibility
  • Softening point

Potential Reasons Crack Bridging Fails

Crack bridging may fail for a variety of reasons. Some pertain to decision-making, such as the choice to use crack bridging on asphalt that has degraded past the point of salvage. Others clearly point to inefficient crack bridging testing. A sampling of crack bridging failure reasons includes:

  • Constant behavioral movement of the structure
  • The presence of groundwater that becomes trapped beneath the crack bridging without an avenue for evaporation
  • Application to asphalt structures that are too degraded to accommodate the treatment
  • Application of crack bridging that is misaligned to the gap’s thickness
  • Application of crack bridging without sufficiently high tensile strength for the project

Reliable, standards-based testing at ACE Laboratories is one of the best strategies for avoiding crack bridging failures.

Partner With ACE Labs For Your Testing Needs

For more than a decade, ACE labs have been a reliable source of world-class research, development and testing. Our ISO/IEC 17025 accreditation and faithful adherence to ASTM International standards highlight our commitment to providing the most accurate, precise data and testing possible. Discover how ACE products and consulting services can give your business a competitive advantage with high-level knowledge and globally respected methods. Ask us anything – we’ll help you find the tools and answers you need to revolutionize your industry.