Production of Asphalt Rubber Concrete by the Dry Process, HR-1062, 1994

Disposal of used tires has been a problem throughout the United States. The 1991 Intermodal Surface Transportation Efficiency Act (ISTEA) requires the use of recycled rubber in asphalt concrete starting in FY94. A moratorium has delayed this requirement until FY95. The Iowa DOT has researched six projects using crumb rubber modifier in asphalt concrete using the wet process. This process involves using a blender-reactor to blend the asphalt cement and crumb rubber. Using the wet process the asphalt cement has to reach a hotter temperature, than is normally required, for reaction to occur. The wet process is also much more expensive than conventional asphalt. This research deals with using a dry process to incorporate crumb rubber into the asphalt concrete mix. The project was constructed by Western Engineering of Harlan, Iowa, on IA 37 between Earling, Iowa and US 59. It was completed in September 1993. Western Engineering used a double drum mixer to produce the crumb rubber modified asphalt concrete by the dry process. The production and construction went well with minor difficulty and the dry process is a less expensive procedure for producing crumb rubber modified asphalt concrete.

Report on a special investigation of the City of Menlo for the period January 1, 2001 through May 31, 2013

Report on a special investigation of the City of Menlo for the period January 1, 2001 through May 31, 2013

Behavior of Asphalts During Production of Asphaltic Concrete Mixes, HR-107, 1965

When mixing asphalt in thin film and at high temperatures, as in the production of asphalt concrete, it has been shown that asphalt will harden due essentially to two factors: (1) losses of volatiles and (2) oxidation. The degree of hardening as expressed by percent loss in penetration varied from as low as 7% to about 57% depending on mixing temperatures, aggregate types, gradation, asphalt content, penetration and other characteristics of asphalts used. Methods used to predict hardening during mixing include loss on heat and thin film oven tests, with the latter showing better correlation with the field findings. However, information on other physical and chemical changes that may occur as a result of mixing in the production of hot-mix asphaltic concrete is limited, The purpose of this research project was to ascertain the changes of asphalt cement properties, both physical and chemical, during mixing operation and to determine whether one or more of the several tests of asphalt cements were critical enough to indicate these changes.

Audit report on the City of Promise City, Iowa for the year ended June 30, 2011

Audit report on the City of Promise City, Iowa for the year ended June 30, 2011

Special investigation of the City of West Liberty for the period July 1, 2010 through January 31, 2014

Special investigation of the City of West Liberty for the period July 1, 2010 through January 31, 2014

Agreed-upon procedures report on the City of Prairie City, Iowa for the period July 1, 2013 through June 30, 2014

Agreed-upon procedures report on the City of Prairie City, Iowa for the period July 1, 2013 through June 30, 2014

Report on a special investigation of the City of Vining for the period May 1, 2008 through May 31, 2014

Report on a special investigation of the City of Vining for the period May 1, 2008 through May 31, 2014

Report on a special investigation of the City of Woodbine Volunteer Fire Department for the period January 1, 2009 through March 31, 2014

Report on a special investigation of the City of Woodbine Volunteer Fire Department for the period January 1, 2009 through March 31, 2014

Agreed-upon procedures report on the City of Gilmore City, Iowa for the period July 1, 2013 through June 30, 2014

Agreed-upon procedures report on the City of Gilmore City, Iowa for the period July 1, 2013 through June 30, 2014

Report on a special investigation of the City of Pacific Junction for the period July 1, 2008 through June 30, 2013

Report on a special investigation of the City of Pacific Junction for the period July 1, 2008 through June 30, 2013

Agreed-upon procedures report on the City of Central City, Iowa for the period July 1, 2013 through June 30, 2014

Agreed-upon procedures report on the City of Central City, Iowa for the period July 1, 2013 through June 30, 2014

Production of Acetic Acid for CMA Deicer, HR-304, 1988

Although the overall objective for undertaking this project is to help decide on the best way to produce CMA, the tasks to be performed deal primarily with acetic acid itself. The objectives of our part of this project can be restated here: A. Evaluate the cost and composition of potential low-cost fermentation substrates that are available in large quantity at central locations in Iowa. B. Compare the nutritional and physiological properties of a variety of homoacetogenic bacteria relative to acetic acid production, based on information available in the literature. C. Using both of these pools of information, evaluate the possibilities for use of substrates for acetic acid production that are significantly cheaper than the previous sugar, starch hydrolysate or whole corn based studies; also, compare the different acetogens encountered with the most commonly discussed acetogen, Clostridium thermoaceticum; arrive at conclusions on 1-3 of the best agriculture-derived substrates that should be further examined, and on 1-3 of the best organisms to evaluate experimentally. D. Collect experimental data at the tube and fermentor scale on 1-2 of the possibilities in C above. E. Comment on our understanding of acetic acid production possibilities from our perspective as microbiologists, and provide all this above information to Paul Peterschmidt for him to consider for his portion of this report. F. In addition, we would like to point out the possible advantage of examining the use of an agricultural by-product, corn steep liquor, as a direct, non-fermented feedstock for a non-acetic acid deicer.

Special investigation of the City of Garwin for the period January 1, 2001 through April 30, 2014

Special investigation of the City of Garwin for the period January 1, 2001 through April 30, 2014

Report on a special investigation of the City of Moorland for the period January 1, 2008 through October 31, 2013

Report on a special investigation of the City of Moorland for the period January 1, 2008 through October 31, 2013

Effect of Anti-Strip Agents on Temperature Susceptibility of Asphalt Cements, MLR-87-01, 1987

Anti-strip agents can effect the temperature susceptibility of asphalt cement. This concern was expressed at the 33rd Annual Bituminous Conference in St. Paul, Minnesota by Mr. David Gendell, Director of Highway Operations. This study compares viscosity-temperature relationships of asphalt cement with and without anti-strip agent addition.