Modification of Ca-Montmorillonite by Low-Temperature Heat Treatment, HR-106, 1964

Objectives of this investigation were to measure the effects of moderate heat treatments (below the dehydroxylation temperature) on physical and chemical properties of a calcium-montmorillonite clay. Previous workers have noted the reduction in cation exchange capacity and swelling property after heating in the range 200 to 400°C, and have suggested several possible explanations, such as hysteresis effect, increased inter-layer attractions due to removal of inter-layer water, or changes in the disposition of inter-layer or layer surface ions. The liquid limits of Ca-montmorillonite were steadily decreased with increased temperature of treatment, levelling at about 450°C. The plastic limit decreased slightly up to 350°C, above which samples could no longer be rolled into threads. The gradual change is in contrast with sudden major changes noted for weight loss (maximum rates of change at l00°C and 500°C), glycol retention surface area (520°C), and d001 diffraction peak intensity (17.7 A spacing) and breadth after glycolation (530°C). Other properties showing more gradual reductions with heat treatment were amount of exchangeable calcium (without water soaking), cation exchange capacity by NH4AC method, and d001 intensity (21 A spacing) after storing at 100% r.h. one month and re-wetting with water. Previous water soaking allowed much greater release of fixed Ca++ up to 450°C. Similar results were obtained with cation exchange capacities when samples were treated with N CaCl2 solution. The 21.0 A peak intensity curve showed close similarity to the liquid limit and plastic index curves in the low temperature range, and an explanation is suggested.

Crack Sealing Utilizing a Heat Lance, HR-2058, 1997

Four Iowa DOT asphalt concrete pavement crack sealing projects were selected to evaluate the benefits of heat lance crack preparation. Two, one-half mile sections, both with and without heat lance preparation, were constructed in Story, Monroe, Clinton and Wayne Counties in 1991 and 1992. They were visually evaluated annually from 1992 through 1996. The heat lance preparation did not yield improved seal performance or extended longevity. There was no perceivable difference between crack sealing with and without heat lance preparation.

Report on a special investigation of the Mahaska County Soil and Water Conservation District for the period March 24, 2006 through August 31, 2013

Report on a special investigation of the Mahaska County Soil and Water Conservation District for the period March 24, 2006 through August 31, 2013

Report on the Iowa Judicial Branch – County Clerks of District Courts, a part of the State of Iowa, for the year ended June 30, 2013

Report on the Iowa Judicial Branch – County Clerks of District Courts, a part of the State of Iowa, for the year ended June 30, 2013

Combined report on the eight Judicial District Departments of Correctional Services for the year ended June 30, 2013

Combined report on the eight Judicial District Departments of Correctional Services for the year ended June 30, 2013

Audit report on Sheldon Community School District in Sheldon, Iowa for the year ended June 30, 2014

Audit report on Sheldon Community School District in Sheldon, Iowa for the year ended June 30, 2014

Report on a special investigation of the Martensdale-St. Marys Community School District for the period July 1, 2009 through April 30, 2014

Report on a special investigation of the Martensdale-St. Marys Community School District for the period July 1, 2009 through April 30, 2014

Report on a special investigation of the Mid-Prairie Community School District for the period July 1, 2012 through June 30, 2014

Report on a special investigation of the Mid-Prairie Community School District for the period July 1, 2012 through June 30, 2014

Audit report on Clarke Community School District in Osceola, Iowa for the year ended June 30, 2014

Audit report on Clarke Community School District in Osceola, Iowa for the year ended June 30, 2014

Issue review : school district cash reserve levy.

During the recent economic crisis, school district budgets have been impacted by state school aid funding shortfalls and state aid reductions due to across-the-board general fund reductions in fiscal year 2009 and fiscal year 2010. Additionally, in fiscal year 2011, the state school aid appropriation was capped and was 156.1 million dollars short of fully funding the state portion of the school aid formula. This issue review examines the impact that the reductions in state aid have had on school district cash reserve levies.

Report on the Historic Preservation and Cultural and Entertainment District Tax Credit program administered by the State Historic Preservation Office within the State Historical Society of Iowa, a division of the Department of Cultural Affairs, for the period July 1, 2000 through June 30, 2013

Report on the Historic Preservation and Cultural and Entertainment District Tax Credit program administered by the State Historic Preservation Office within the State Historical Society of Iowa, a division of the Department of Cultural Affairs, for the period July 1, 2000 through June 30, 2013

Audit report on the Xenia Rural Water District for the year ended December 31, 2014

Audit report on the Xenia Rural Water District for the year ended December 31, 2014

Report on a special investigation of the band program of the Monticello Community School District for the period January 1, 2009 through December 31, 2013

Report on a special investigation of the band program of the Monticello Community School District for the period January 1, 2009 through December 31, 2013

Report on a special investigation of the Shenandoah Community School District for the period July 1, 2012 through September 30, 2014

Report on a special investigation of the Shenandoah Community School District for the period July 1, 2012 through September 30, 2014