Report on a special investigation of the Benton County Conservation Department for the period June 1, 2010 through November 7, 2011

Report on a special investigation of the Benton County Conservation Department for the period June 1, 2010 through November 7, 2011

Investigation of Electromagnetic Gauges for Determining In-Place HMA Density, Final Report, May 2007

Density is an important component of hot-mix asphalt (HMA) pavement quality and long-term performance. Insufficient density of an in-place HMA pavement is the most frequently cited construction-related performance problem. This study evaluated the use of electromagnetic gauges to nondestructively determine densities. Field and laboratory measurements were taken with two electromagnetic gauges—a PaveTracker and a Pavement Quality Indicator (PQI). Test data were collected in the field during and after paving operations and also in a laboratory on field mixes compacted in the lab. This study revealed that several mix- and project-specific factors affect electromagnetic gauge readings. Consequently, the implementation of these gauges will likely need to be done utilizing a test strip on a project- and mix-specific basis to appropriately identify an adjustment factor for the specific electromagnetic gauge being used for quality control and quality assurance (QC/QA) testing. The substantial reduction in testing time that results from employing electromagnetic gauges rather than coring makes it possible for more readings to be used in the QC/QA process with real-time information without increasing the testing costs.

Investigation of Warm-Mix Asphalt Using Iowa Aggregates Final Report, April 2011

The implementation of warm-mix asphalt (WMA) is becoming more widespread with a growing number of contractors utilizing various WMA technologies. Early research suggests WMA may be more susceptible to moisture damage than traditional hot-mix asphalt (HMA) mixes. The objectives of this study are to test the binder and mix properties of WMA technologies for both field- and laboratory-produced mixes to determine the performance of WMA compared to traditional HMA. Field- and laboratory-produced mixes were studied. The laboratory-produced mixes compared HMA control mixes with WMA mixes that had the same mix design. The WMA technologies used for the laboratory study were Advera, Sasobit, and Evotherm. The field study tested four WMA field-produced mixes. Each of the four mixes had a corresponding control HMA mix. The WMA technologies used in the field study included: Evotherm 3G/Revix, Sasobit, and Double Barrel Green Foaming. The three main factors for this study were WMA/HMA, moisture-conditioned/not moisture-conditioned, and reheated/not reheated. Mixes were evaluated based on performance tests. Binder testing was performed to determine the rheological differences between HMA and WMA binders to determine if binder grade requirements change with the addition of WMA additives. The conclusions of this study are as follows:  Reduced mixing and compaction temperatures were achieved.  Statistical differences were found when comparing tensile strength ratio (TSR) values for both laboratory- and field-produced mixes. In the laboratory, none of the WMA additives performed as well as the HMA. For the field mixes, all TSR values passed Iowa’s minimum specification of 0.8 but, on average, WMA is lower compared to HMA TSR values.  Dynamic modulus results show that, on average, HMA will have higher dynamic modulus values. This means the HMA exhibits stiffer material properties compared to WMA; this may not necessarily mean superior performance in all cases.  Flow number results show that WMA has reduced flow number values compared to HMA. The only exception was the fourth field mix and weather delayed production of the control mix by nine days. The laboratory mixes showed that flow number values increased significantly with the addition of recycled asphalt pavement (RAP).  In the laboratory study, Advera reduced TSR values. Given that Advera is a foaming agent, the increase in moisture susceptibility is likely attributed to the release of water necessary for the improvement of the workability of the asphalt mixture.

Report on a special investigation of the City of Blencoe for the period January 1, 2008 through September 30, 2011

Report on a special investigation of the City of Blencoe for the period January 1, 2008 through September 30, 2011

Investigation of Earlham Community School District Employee’s Personal Use of a School Vehicle, July 6, 2012

We received a complaint in late September 2011 that an Earlham School District employee had borrowed a school vehicle for her personal use for one month, with the Superintendent’s permission. The school board had discussed the circumstances of the borrowed district vehicle in closed session. The complainant believed this was contrary to Iowa law and also believed no action had been taken against the school employee who borrowed the vehicle or the superintendent who allowed the personal use of the vehicle. He was aware the school district’s attorney reviewed the matter and determined the employee and superintendent violated no law or district policies. Since the school board discussed the matter only in closed session, it was unknown what, if any, discipline was taken against the employees and whether such actions were condoned by the district. We agreed to investigate to determine if the actions of school officials or employees violated Iowa law and if the response from the school board was appropriate.

Report on a special investigation of the New Hampton Municipal Light Plant for the period January 1, 2001 through May 31, 2012

Report on a special investigation of the New Hampton Municipal Light Plant for the period January 1, 2001 through May 31, 2012

Report on a special investigation of the University of Iowa Hospital and Clinics, Department of Orthopaedics and Rehabilitation, for the period December 1, 2002 through January 31, 2012

Report on a special investigation of the University of Iowa Hospital and Clinics, Department of Orthopaedics and Rehabilitation, for the period December 1, 2002 through January 31, 2012

Report on a special investigation of the Southwest Iowa Transit Agency for the period July 1, 2011 through June 30, 2012

Report on a special investigation of the Southwest Iowa Transit Agency for the period July 1, 2011 through June 30, 2012

Report on a special investigation of the City of Buffalo for the period September 25, 2008 through September 30, 2010

Report on a special investigation of the City of Buffalo for the period September 25, 2008 through September 30, 2010

Report on a special investigation of the Adair County Engineer’s Office for the period December 5, 2001 through December 31, 2011

Report on a special investigation of the Adair County Engineer’s Office for the period December 5, 2001 through December 31, 2011

Report on a special investigation of the City of Masonville for the period of March 18, 2002 to November 30, 2011

Report on a special investigation of the City of Masonville for the period of March 18, 2002 to November 30, 2011

Report on a special investigation of the Coggon Municipal Light Plant for the period July 1, 2004 through August 27, 2012

Report on a special investigation of the Coggon Municipal Light Plant for the period July 1, 2004 through August 27, 2012

Report on a special investigation of the City of Stockport for the period July 1, 2007 through October 31, 2011

Report on a special investigation of the City of Stockport for the period July 1, 2007 through October 31, 2011

Report on a special investigation of the City of Muscatine for the period July 1, 2008 through March 8, 2012

Report on a special investigation of the City of Muscatine for the period July 1, 2008 through March 8, 2012

Special investigation of the Iowa Department of Transportation for the period January 29, 1994 through July 7, 2011

Special investigation of the Iowa Department of Transportation for the period January 29, 1994 through July 7, 2011