Concrete Pavement Mixture Design and Analysis (MDA): Application of a Portable X-Ray Fluorescence Technique to Assess Concrete Mix Proportions , TPF-5(205), 2012

Any transportation infrastructure system is inherently concerned with durability and performance issues. The proportioning and uniformity control of concrete mixtures are critical factors that directly affect the longevity and performance of the portland cement concrete pavement systems. At present, the only means available to monitor mix proportions of any given batch are to track batch tickets created at the batch plant. However, this does not take into account potential errors in loading materials into storage silos, calibration errors, and addition of water after dispatch. Therefore, there is a need for a rapid, cost-effective, and reliable field test that estimates the proportions of as-delivered concrete mixtures. In addition, performance based specifications will be more easily implemented if there is a way to readily demonstrate whether any given batch is similar to the proportions already accepted based on laboratory performance testing. The goal of the present research project is to investigate the potential use of a portable x-ray fluorescence (XRF) technique to assess the proportions of concrete mixtures as they are delivered. Tests were conducted on the raw materials, paste and mortar samples using a portable XRF device. There is a reasonable correlation between the actual and calculated mix proportions of the paste samples, but data on mortar samples was less reliable.

Refinement of Rapid PCC Coarse Aggregate Testing Program, HR-1071, 1999

The characterization and categorization of coarse aggregates for use in portland cement concrete (PCC) pavements is a highly refined process at the Iowa Department of Transportation. Over the past 10 to 15 years, much effort has been directed at pursuing direct testing schemes to supplement or replace existing physical testing schemes. Direct testing refers to the process of directly measuring the chemical and mineralogical properties of an aggregate and then attempting to correlate those measured properties to historical performance information (i.e., field service record). This is in contrast to indirect measurement techniques, which generally attempt to extrapolate the performance of laboratory test specimens to expected field performance. The purpose of this research project was to investigate and refine the use of direct testing methods, such as X-ray analysis techniques and thermal analysis techniques, to categorize carbonate aggregates for use in portland cement concrete. The results of this study indicated that the general testing methods that are currently used to obtain data for estimating service life tend to be very reliable and have good to excellent repeatability. Several changes in the current techniques were recommended to enhance the long-term reliability of the carbonate database. These changes can be summarized as follows: (a) Limits that are more stringent need to be set on the maximum particle size in the samples subjected to testing. This should help to improve the reliability of all three of the test methods studied during this project. (b) X-ray diffraction testing needs to be refined to incorporate the use of an internal standard. This will help to minimize the influence of sample positioning errors and it will also allow for the calculation of the concentration of the various minerals present in the samples. (c) Thermal analysis data needs to be corrected for moisture content and clay content prior to calculating the carbonate content of the sample.

Transportation Program Management System, HR-394, 2003

HR-394 was a software and database development project. Via funding provided by the Iowa Highway Research Board, the Iowa County Engineer's Association Service Bureau oversaw the planning and implementation of an Internet based application that supports two major local-government transportation project activities: Project programming and Development tracking. The goals were to reduce errors and inconsistencies, speed up the processes, link people to both project data and each other, and build a framework that could eventually support a 'paperless' work flow. The work started in 1999 and initial development was completed by the fall of 2002. Since going live, several 'piggy back' applications have been required to make the Programming side better fit actual work procedures. This part of the system has proven adequate but will be rewritten in 2004 to make it easier to use. The original development side module was rejected by the users and so had to be rewritten in 2003. The second version has proven much better, is heavily used, and is interconnected with Iowa DOT project data systems. Now that the system is in operation, it will be maintained and operated by the ICEA Service Bureau as an ongoing service function.

A-8a 2003 Summary of Food Stamp Errors - Active and Negative Cases, April 2003 - September 2003

Summary of food stamp errors.

A8a Summary of Food Stamp Errors-Active and Negative cases, July 2004

A-8A summary of food stamp errors active and negative cases

A-8a 2003 Summary of Food Stamp Errors - Active and Negative Cases, April 2001 - September 2001

Summary of food stamp errors.

A-8a Summary of Food Stamp Errors Active and Negative Cases, April-September 2004

A-8a Summary of Food Stamp Errors Active and Negative Cases, Apr. 2004 - Sept. 2004

A-8a Summary of Food Stamp Errors Active and Negative Cases, October 2004-March 2005

A-8a Summary of Food Stamp Errors Active and Negative Cases, Oct. 2004 - Mar. 2005

A-8a Summary of Food Stamp Errors - Active and Negative Cases, April 2003-September 2003

Summary of food stamp errors.

A-8a Summary of Food Stamp Errors - Active and Negative Cases, October 2001-March 2002

Summary of food stamp errors.

A-8a Summary of Food Stamp Errors - Active and Negative Cases, Aprril 2002-September 2002

Summary of food stamp errors.

Prevalence and Distribution of Young Driver Distraction Errors in Naturalistic Driving, TPF-5(207), 2014

Naturalistic driving studies are the latest resource for gathering data associated with driver behavior. The University of Iowa has been studying teen driving using naturalistic methods since 2006. By instrumenting teen drivers’ vehicles with event-triggered video recorders (ETVR), we are able to record a 12-second video clip every time a vehicle exceeds a pre-set g-force threshold. Each of these video clips contains valuable data regarding the frequency and types of distractions present in vehicles driven by today’s young drivers. The 16-year old drivers who participated in the study had a distraction present in nearly half of the events that were captured. While a lot of attention has been given to the distractions associated with technology in the vehicle (cell phones, navigation devices, entertainment systems, etc.), the most frequent type of distraction coded was the presence of teen passengers engaging in conversation (45%). Cognitive distractions, such as singing along with the radio, were the second most common distraction. Cell phone use was the third most common distraction, detected in only 10% of the events containing distraction.