Laboratory Performance Testing Services of the Asphalt Institute

Mixture Performance Testing

The Asphalt Institute provides performance testing services that predict potential behavior of an asphalt mixture. This allows one mixture to be compared to another, or can be used to better understand how one variable can change the performance of a mixture.

Superpave Shear Test (SST)

Indirect Tension Test (IDT) – Creep and Strength

Flexural Beam Fatigue

Simple Performance Test (SPT)

Resilient Modulus

Asphalt Pavement Analyzer (APA)

Hamburg Wheel Tracker (HWT)

Superpave Shear Test (SST)
Developed through the Strategic Highway Research Program (SHRP), the SST can run: Repeated Shear at Constant Height (RSCH) at highway pavement layer temperatures usually over 100 degrees F. The RSCH pulses the sample and then allows it to relax for a more accurate visco-elastic rutting response. The loading cycle is usually repeated for 5,000 cycles. This test is thought by some asphalt technologists to be the best predictive rutting analysis available. This is a destructive test. Frequency Sweep at Constant Height (FSCH) test to measure the shear complex modulus (G*)¹ and phase angle of a mixture. The FSCH is a strain-controlled test where the resultant stress is measured over a range of temperatures and frequencies. The modulus data is used to understand a mixture's ability to respond to slow and fast loads at high and low temperatures. Simple Shear Test at Constant Height test measures shear force required to shear a sample. This is a destructive test².

Indirect Tension Test (IDT) – Creep and Strength
Also developed by SHRP, the IDT creep and strength tests measure the low temperature compliance (ability of a mixture to relax at cold temperatures) and the fracture strength of a mixture at temperatures well below freezing. This test is used to predict the low temperature cracking temperature of a mixture. The fracture strength is a destructive test.

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Flexural Beam Fatigue
Developed during SHRP, the 4-point beam fatigue apparatus allows one to measure the flexibility of a mixture usually through repeated strain cycles. Commonly used for understanding fatigue failure, it is not limited to only classic pavement fatigue. This test is also used to understand the brittleness of a mixture. At extreme high strains, this device is used to simulate the joint movement of Portland cement concrete (PCC) joints. This is a destructive test.

Simple Performance Test (SPT)
One of the newest tests to the asphalt industry is the SPT. The SPT was developed under the NCHRP 9-29 research following guidance from the NCHRP 9-19 research. It is considered a more simple and practical method of measuring the modulus and rutting potential of a mixture.

SPT dynamic modulus (E*) data is used in the Mechanistic Empirical Pavement Design Guide (MEPDG) for pavement thickness design and performance prediction.SPT Flow Number test is a new and upcoming rutting test that seems to predict rutting potential well. This is a destructive test.

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Resilient Modulus
Probably one of the most widely used of the modulus tests. The resilient modulus test configuration allows samples to be tested on end, making it popular for pavement cores.

Asphalt Pavement Analyzer (APA)
The APA originated in Georgia from the concept of microsurface/slurry rut testing. GA developed the APA so it could measure the rutting risk of asphalt mixtures before placement. The APA is still used by the GA DOT for proof testing of mixtures. This test seems to be most widely used in the Eastern U.S. This is a destructive test.

Hamburg Wheel Tracker (HWT)
The HWT test was developed in Hamburg , Germany and used to measure both rutting and stripping risk. If passing, mixtures were accepted in Germany for five-year warranties. This test is most widely used in the mid-western and western U.S.

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Modulus = stress/strain. This measures a mixture's stress in response to a movement (strain).
The sample cannot be re-used for other testing

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