NCAT Designated as NTPEP Testing Laboratory

The National Transportation Product Evaluation Program (NTPEP) is a national testing program hosted by the American Association of State Highway and Transportation Officials (AASHTO). This voluntary program was established to minimize the duplication of efforts among AASHTO member states by providing a process where manufacturers and suppliers submit products for independent testing. The results are then shared with AASHTO member states for their own use in product approval or product quality verification.

NTPEP is truly a win-win cooperative partnership between state DOTs and transportation industry participants. From a state’s perspective, NTPEP provides benefits including cost savings from reduced testing and auditing resources, improved product quality acceptance, reliable independent test results, and shared expertise and experience with other states. The benefits of NTPEP for suppliers are also substantial because it provides an opportunity to have their products exposed to all AASHTO member states at once, significantly shortening the product evaluation and approval process.

NTPEP currently has 24 product evaluation programs, with one being warm mix asphalt (WMA) additives and anti-strip additives (ASA). WMA and ASA are widely used asphalt technologies that provide environmental and performance benefits to asphalt paving mixtures. The objective of the WMA and ASA evaluation program is to compare mixes containing various WMA and/or ASA technologies to hot mix asphalt control mixes using the same asphalt binder and aggregate to determine relative performance.

Table 1 shows a list of laboratory tests required for the evaluation of WMA and ASA technologies. The asphalt binder used in the program for laboratory-produced mixes is a neat PG 64-22 binder without modification. The WMA evaluation is based on a limestone mix design while the ASA evaluation requires two mix designs, one using a limestone aggregate and the other using a granite aggregate. A detailed work plan of the program can be found on the NTPEP website at

Table 1. Laboratory tests for NTPEP evaluation of WMA and ASA technologies.


NCAT was selected as the testing laboratory for NTPEP’s WMA and ASA program in 2019. NCAT has completed the evaluation of eight products to date, including four WMA additives, three ASA additives, and one WMA plus ASA combined additive. Testing results of these products are available in the NTPEP DataMine online database at

NTPEP and NCAT have agreed to open three product submission cycles for 2020. The first cycle opened February 6, 2020 and closed February 28. Four WMA and ASA products were received. Testing at NCAT will commence in early April with an anticipated completion date of July 31, 2020. The other two submission cycles will open on June 1 and October 1, 2020.

Yin Fan

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