ELASTICITY TESTING
ASTM D6084 is used to measure the elastic recovery of bituminous materials. Bituminous materials are thick, dark mixtures of hydrocarbons derived from petroleum or rock deposits. A bituminous material may also include thermoplastic or other raw materials, which are often added to enhance its performance characteristics.
Common examples of bituminous materials include asphalt, tar, and pitch. Bituminous materials are most often used in road construction and roofing and may also be used in waterproofing applications.
Elasticity is a vital characteristic of bituminous materials, especially in road construction applications. Roadways themselves are prone to shifting over time due to climate and other factors, and bituminous materials used in road construction must be able to weather these changes without cracking or tearing. Good elasticity also reduces the road surface’s vulnerability to rutting at high temperatures and cracking at low temperatures.
Elasticity testing—also called elastic recovery testing—is an excellent way to determine the elasticity of a bituminous material in a controlled laboratory setting. Elasticity testing allows manufacturers to verify the elastic recovery performance of a bituminous material and benchmark the performance of different polymers in the asphalt matrix.
WHAT DOES ELASTICITY MEASURE?
Elasticity refers to a material’s ability to stretch—and return to its original shape. Elasticity testing measures how much and how quickly a material recovers from elongation or strain. Elasticity testing can also determine whether a material can recover under different environmental conditions. Elasticity testing may be conducted in cold temperatures to predict how a material might perform in the winter and, in turn, how a roadway surface may be impacted by winter weather.
ASTM D6084 TEST DETAILS
The ASTM D6084 test method is conducted using a ductilometer. A ductilometer is a specialized testing apparatus designed specifically for bituminous materials. Most ductilometers are made with a testing carriage and tension system for stretching prepared samples and a water bath with tight temperature controls for sample conditioning.
To conduct the test, a prepared sample is loaded into the ductilometer and lowered into the water bath, which has been programmed for a specific temperature. The sample remains in the water bath for roughly ninety minutes. Immediately upon removal, the sample is then elongated at a determined speed and temperature, using the ductilometer’s tension system. At the appropriate interval, the specimen is severed in two using scissors and left to rest.
After a determined period of time has passed, the two halves of the sample are brought together via the ductilometer’s carriage and measured. This measurement, when compared to the measurement of the sample pre-test, is used to calculate the elastic recovery of the material.
Elastic recovery is usually measured by percentage. In general, a sample that achieves 75% recovery or higher is a good benchmark for acceptability. However, some test standards or criteria will require a higher recovery percentage.
Applications of ASTM D6084
The primary purpose of ASTM D6084 is to demonstrate compliance with performance regulations for bituminous materials. However, the standard can be used for other purposes. Many manufacturers may use ASTM D6084 during research and development (R&D) to investigate the suitability of different polymers in a bituminous mixture. ASTM D6084 can be an excellent benchmarking tool for comparing the performance of several different polymers with regard to elastic recovery of the bituminous material.
It’s also worth noting that the ASTM D6084 method can be conducted on both aged and unaged samples of bituminous material. This means that ASTM D6084 can be used to measure the elastic recovery of bituminous materials that have:
- Already seen service, or
- Been subjected to artificial weathering or accelerated aging conditions in a controlled laboratory setting.
This allows manufacturers and product development teams to test and predict the long-term performance of a bituminous material, especially how its elasticity may evolve over time as the material is exposed to sun, ozone, and other environmental conditions.
Elasticity Recovery Testing from ACE Laboratories
ACE Laboratories has an entire team devoted to providing top-quality testing data for construction materials, offering some of the fastest turnaround times in the industry. Our experts have years of experience working with rubber, so we can help you understand the behavior and role of polymer materials in a bituminous mixture. Whether you’re looking to study a few different polymer choices, understand the impact of aging on bituminous materials, or optimize performance of your product, you can count on ACE to provide the expert guidance and clear data you need to move your project forward.
To learn more about elastic recovery testing and other services we offer the construction industry, get in touch with a member of the ACE team.
