Development of Quality Standards for Inclusion of High Recycled Asphalt Pavement Content in Asphalt Mixtures – Phase II, TR-658, 2015

To conserve natural resources and energy, the amount of recycled asphalt pavement has been steadily increasing in the construction of asphalt pavements. The objective of this study is to develop quality standards for inclusion of high RAP content. To determine if the higher percentage of RAP materials can be used on Iowa’s state highways, three test sections with target amounts of RAP materials of 30%, 35% and 40% by weight were constructed on Highway 6 in Iowa City. To meet Superpave mix design requirements for mixtures with high RAP contents, it was necessary to fractionate the RAP materials. Three test sections with actual RAP materials of 30.0%, 35.5% and 39.2% by weight were constructed and the average field densities from the cores were measured as 95.3%, 94.0%, and 94.3%, respectively. Field mixtures were compacted in the laboratory to evaluate moisture sensitivity using a Hamburg Wheel Tracking Device. After 20,000 passes, rut depths were less than 3mm for mixtures obtained from three test sections. The binder was extracted from the field mixtures from each test section and tested to identify the effects of RAP materials on the performance grade of the virgin binder. Based on Dynamic Shear Rheometer and Bending Beam Rheometer tests, the virgin binders (PG 64-28) from test sections with 30.0%, 35.5% and 39.2% RAP materials were stiffened to PG 76-22, PG 76-16, and PG 82-16, respectively. The Semi-Circular Bending (SCB) test was performed on laboratory compacted field mixtures with RAP amounts of 30.0%, 35.5% and 39.2% at two different temperatures of -18 and -30 °C. As the test temperature decreased, the fracture energy decreased and the stiffness increased. As the RAP amount increased, the stiffness increased and the fracture energy decreased. Finally, a condition survey of the test sections was conducted to evaluate their short-term pavement performance and the reflective transverse cracking did not increase as RAP amount was increased from 30.0% to 39.2%.

Missing Persons Summary, May 5, 2003

Missing persons summary

City of Center Point, June 30, 2002

City Audit Report

Iowa Department of Transportation Major Items - Preliminary Quantity Report, January 16, 2013; With Addendums

Weekly letting report.

1014-008 Walnut Creek Watershed Final Report

In 2004, Walnut Creek was placed on the 303d list of Impaired Waters due to a low biotic index (lack of aquatic life) during IDNR stream sampling events. Sediment originating from agriculture, streambank erosion, and channelization were listed as the most likely sources impacting aquatic life. In an effort to address these concerns, a preliminary study was completed of the multi-county watershed to identify priority areas. A Watershed Development & Planning Assistance Grant was then funded by the IDALS-DSC to conduct a detailed assessment of these prioritized sub-watersheds. The impending assessment of the watershed and the stream corridor revealed ample opportunities to address gully, sheet and rill erosion while addressing in-stream water velocity issues that plagued the riparian corridor. A comprehensive plan was developed comprised of a variety of best management practices to address the identified concerns. In 2009, this plan was submitted to the WIRB Board by the East Pottawattamie and Montgomery SWCDs and $489,455 was awarded to address concerns identified during watershed assessment inquiries. Despite adverse weather conditions, which has hampered conservation construction recently, this project has held fast to pre-project goals due to the fortitude of the project sponsors and the overwhelming participation by the watershed landowners. Unfortunately, state budget shortfalls are bringing project progress to a halt. As specified in the original WIRB funding request, practice funding for Year 3 was to come from the Division of Soil Conservation’s Watershed Protection Fund (WSPF). Due to Iowa’s budgetary restraints, the Walnut Creek WSPF application, which was submitted this spring, was not funded since no new applications in the state were funded. If funded again, this grant will serve as the critical step in continuing what is destined to be a true watershed success story.