In Phase II of NCHRP Project 9-29, a detailed purchase specification was developed for equipment to perform the three Project 9-19 simple performance tests: dynamic modulus, flow number, and flow time. The specification was used to procure two simple performance test systems from Interlaken Technology Corporation and Shedworks, Incorporated. http://gulliver.trb.org/publications/nchrp/nchrp_rpt_513.pdfThese two systems were similar in several critical design areas. Both are relatively small bottom-loading, servo-hydraulic devices with an automated test chamber that serves as both the confining pressure cell and the environmental chamber. The primary differences between the devices are (1) the specific methods used to heat and cool the chamber and (2) the specimen-mounted deformation measuring system used exclusively in the dynamic modulus test. The Interlaken device uses heating elements and an air-driven vortex cooler to control temperature in the chamber. The specimen deformation measuring system is a unique extensometer system held against the specimen with small pneumatic actuators. The Shedworks device circulates conditioned air through the test chamber. The specimen deformation measuring system is a refined version of the glued contact point system used in the original Project 9-19 research. An extensive evaluation of these two devices was undertaken in Phase II of Project 9-29. This evaluation included (1) specific testing to ensure that the devices were in compliance with the specifications and properly calibrated and (2) an extensive mixture testing program to evaluate mechanical properties measured with the two devices and to assess the functionality of the devices. The overall findings from the evaluation were as follows: 1. Both devices meet the requirements of the first-article specifications and are reasonably user-friendly. Both have functional deficiencies that need to be addressed in future production units. 2. For the dynamic modulus test, the evaluation testing revealed significant differences in both the mean and the variability of dynamic modulus data collected with the two devices. These differences appear to be associated with differences in the specimen-mounted deformation measuring system. 3. The overall variability of the dynamic modulus test was found acceptable for specification testing, and the variability is expected to decrease as limits are placed on the quality indicators developed in this project for the dynamic modulus test. (Author/publisher) This report may be accessed by Internet users at
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