ASTM C1305 Standard Test Method for Crack Bridging Ability of Liquid-Applied Waterproofing Membrane

Get Certified ASTM C1305/C1305M Testing for Reliable Crack Bridging Evaluation 

ASTM C1305/C1305M is a controlled laboratory test method to assess the cracking resistance of waterproofing membranes. Qualified technicians prepare cracked mortar assemblies and install the membrane following the applicable manufacturer’s instructions. The assemblies are conditioned and subjected to repeated movement at low temperatures to test the membrane’s integrity. Controlled specimen preparation, temperature, membrane application, movement, and final inspection are important factors for reliable evaluation.

The scope of ASTM C1305/C1305M includes:

• Material: Liquid-applied waterproofing membrane materials intended to form a continuous waterproofing layer over a substrate. 
• Objective: To determine whether the membrane can span a crack or fissure in the substrate. 
• Property measurement: Crack-bridging ability and the membrane’s ability to remain intact during repeated substrate movement at low temperature. 
• Method: The membrane specimens are placed on cracked mortar plates, conditioned, cooled, and then repeatedly opened and closed. 
• Result: The membrane is visually inspected after the number of movements indicated for cracking, separation, pinholes, or loss of integrity in the test area. 
• Test limitations: This laboratory procedure provides only a single condition of crack movement at low temperature and is not representative of all the substrate, environmental, loading, and field service conditions. 
• Environmental conditions: The test involves movement testing at low temperatures, as well as controlled conditioning; the cold box can achieve about −26°C, and the tolerance is defined by the method. 
• Applications: Waterproofing membrane research, product development, quality evaluation, specification testing, and assessment of low-temperature crack-bridging performance.

What are the uses of ASTM C1305/C1305M testing? 

ASTM C1305/C1305M is a test to determine if a waterproofing membrane fails to maintain continuity when a substrate crack opens and closes under a low-temperature condition. This information can support product evaluation and waterproofing-system development. This standard-

• Determines the capacity of waterproofing membranes to be applied to cracks already existing in the substrate. 
• Assesses the integrity of membranes when they are subjected to repeated crack movement at low ambient temperature. 
• Facilitates comparison of formulations and systems for waterproofing in a controlled lab setting. 
• Measures the performance of products where cracking and movement in the substrate could compromise waterproofing. 
• Can qualify, research and develop, evaluate, and test products in accordance with specifications. 
• Suggests a standard lab test to assess membrane damage following repeated movement.

Which Materials Can Be Tested Under ASTM C1305/C1305M? 

ASTM C1305/C1305M applies to materials used for liquid-applied waterproofing membranes that can be applied to the test substrate and cured or conditioned before movement testing. The technique uses mortar blocks with an existing crack as the primary substrate.

Why is ASTM C1305/C1305M Important?

ASTM C1305/C1305M provides a test to evaluate a waterproofing membrane’s ability to maintain integrity across a moving crack. This is significant because if the membrane is not continuous over a substrate crack, it may no longer act as a waterproofing barrier. The low-temperature condition is significant because the membrane is less likely to be flexible at low temperatures.
ASTM C1305/C1305M Equipment and Sample Preparation Guide

Technicians choose and set up equipment as per test assembly and low-temperature moving requirements of ASTM C1305/C1305M. Experienced personnel mix the mortar substrate around an existing crack, spread the membrane evenly as per the manufacturer’s instructions, and condition the substrate before the movement tests.

ASTM C1305/C1305M Testing Process and Data Collection 

In the ASTM C1305/C1305M testing, five specimens of each membrane type are prepared on mortar substrates with existing cracks. The specimens are conditioned for 14 days at standard conditions and then exposed to seven days of circulating hot-air oven conditioning at 70°C [158°F]. After cooling, the assemblies are installed in the test machine and subjected to ten movement cycles at low temperature. The final evaluation focuses on the membrane’s condition over the moving joint. Technicians inspect the test area for visible cracking, separation, pinholes, or other evidence that the membrane has failed to maintain its integrity while bridging the substrate crack.

Common Challenges and Troubleshooting 

Accurate ASTM C1305/C1305M results depend on consistent substrate preparation, correct membrane mixing and application, controlled curing and conditioning, and stable low-temperature movement testing. The membrane response can be affected by uneven thickness of the membrane, improper preparation of the substrate, inadequate mixing of multi-component materials, improper conditioning, or temperature instability. The technicians must follow the manufacturer’s preparation requirements, keep the same test assemblies, check the cold box and oven conditions, and check the membrane after the movement cycles, etc.

• Laboratories document the applicable specimen dimensions, temperature conditions, movement conditions, and other test parameters using the selected SI or inch-pound system independently.
• The principal evaluation is the membrane’s ability to maintain integrity while bridging the preexisting crack during the specified movement cycles. 
• Analysts record visible cracking, separation, pinholes, or other membrane conditions observed at the substrate joint after testing. 
• Results are interpreted according to the ASTM C1305/C1305M procedure and any product specification or project acceptance requirements that reference the test method.

Link to ASTM C1305/C1305M