A “performance engineered mixtures (PEM) and PEM testing methods” OPEN HOUSE EVENT was held August 7, 2019. Cosponsored by the Federal Highway Administration (FHWA), Illinois DOT (IDOT), and Illinois Chapter-ACPA, the event began in Moline, Illinois, with presentations describing the PEM approach; followed by PEM test demonstrations in nearby Davenport, Iowa (at Hahn Ready Mix, Sand & Gravel). Attendees included about 40 professionals representing the FHWA, IDOT, industry, and the National Concrete Pavement Technology Center (CP Tech Center).
PEM was developed in part, due to the traditional testing and acceptance methods, which are based on factors such as strength, slump and air. According to the CP Tech Center, although these are measures of quality, they have little correlation to future performance. The goal of the PEM transportation pooled fund is âto bring new testing technologies to state agencies and assist in new test methods that will help deliver durable, long-lasting concrete.â
Peter Taylor, CP Tech Center, provided an overview of the PEM approach. âWe need to make a spec that works better than what we have at the moment,â he said in his opening remarks.
James Krstulovich, IDOT, provided an agency perspective on PEM. âAs we move away from prescriptive specs, method specsâ and move toward giving the contractor and the producer ownership of their mix designs, we have to keep moving away from the prescription, giving the freedom and innovation over to the people making (the concrete),â he said.
Mike Ayers, Illinois Chapter-ACPA, provided an industry perspective, and said âWhat we donât consider in pavement design is durability issues, and thatâs whatâs coming back to haunt us. PEMs are going to go a long way in alleviating that problem.â
Following the insightful presentations, the DOT also provided a brief overview of the I-74 reconstruction project, a joint project among the Illinois and Iowa DOTs to improve the I-74 corridor from Moline to Davenport. The project includes the replacement of the I-74 bridges over the Mississippi River as well as interchange ramp reconfigurations and local roadway improvements, according to the I-74 River Bridge website.
The open house continued in the afternoon with demonstrations and interactive discussions about the testing methods that support PEM. They are:
Super Air Meterâmeasures air-void characteristics of concrete
Surface resistivity testingâa rapid measurement technique to determine the permeability of concrete
Box testâa measurement of workability
V-Kelly testâa measurement of workability
For the I-74 River Bridge Website, please go to: http://i74riverbridge.com
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Photo: (L-R) Mike Ayers and Peter Taylor discuss surface resistivity testing during the PEM workshop. (Photo by Bill Davenport for ACPA)