Development of In-Situ Detection Methods for Materials-Related Distress (MRD) in Concrete Pavements, July 2003

The purpose of this research was to summarize existing nondestructive test methods that have the potential to be used to detect materials-related distress (MRD) in concrete pavements. The various nondestructive test methods were then subjected to selection criteria that helped to reduce the size of the list so that specific techniques could be investigated in more detail. The main test methods that were determined to be applicable to this study included two stress-wave propagation techniques (impact-echo and spectral analysis of surface waves techniques), infrared thermography, ground penetrating radar (GPR), and visual inspection. The GPR technique was selected for a preliminary round of “proof of concept” trials. GPR surveys were carried out over a variety of portland cement concrete pavements for this study using two different systems. One of the systems was a state-of-the-art GPR system that allowed data to be collected at highway speeds. The other system was a less sophisticated system that was commercially available. Surveys conducted with both sets of equipment have produced test results capable of identifying subsurface distress in two of the three sites that exhibited internal cracking due to MRD. Both systems failed to detect distress in a single pavement that exhibited extensive cracking. Both systems correctly indicated that the control pavement exhibited negligible evidence of distress. The initial positive results presented here indicate that a more thorough study (incorporating refinements to the system, data collection, and analysis) is needed. Improvements in the results will be dependent upon defining the optimum number and arrangement of GPR antennas to detect the most common problems in Iowa pavements. In addition, refining highfrequency antenna response characteristics will be a crucial step toward providing an optimum GPR system for detecting materialsrelated distress.

Material and Construction Optimization for Prevention of Premature Pavement Distress in PCC Pavements, September 2004

The chemistry of today’s concrete mixture designs is complicated by many variables, including multiple sources of aggregate and cements and a plethora of sometimes incompatible mineral and chemical admixtures. Concrete paving has undergone significant changes in recent years as new materials have been introduced into concrete mixtures. Supplementary cementitious materials such as fly ash and ground granulated blast furnace slag are now regularly used. In addition, many new admixtures that were not even available a few years ago now have widespread usage. Adding to the complexity are construction variables such as weather, mix delivery times, finishing practices, and pavement opening schedules. Mixture materials, mix design, and pavement construction are not isolated steps in the concrete paving process. Each affects and is affected by the other in ways that determine overall pavement quality and long-term performance. Equipment and procedures commonly used to test concrete materials and concrete pavements have not changed in decades, leaving serious gaps in our ability to understand and control the factors that determine concrete durability. The concrete paving community needs tests that will adequately characterize the materials, predict interactions, and monitor the properties of the concrete.

Influenza and Other Respiratory Virus Weekly Activity Report, May 16, 2009 Week 19

The Iowa Influenza Surveillance Network (IISN) is comprised of physicians, schools, child care centers, businesses, and long term care facilities who track the occurrence on influenza-like illness. In addition, the state influenza coordinator tracks the number of deaths due to pneumonia and influenza in Des Moines weekly as part of the 122-Cities Morbidity and Mortality reporting system sponsored by CDC.

Influenza and Other Respiratory Virus Weekly Activity Report, May 9, 2009 Week 18

The Iowa Influenza Surveillance Network (IISN) is comprised of physicians, schools, child care centers, businesses, and long term care facilities who track the occurrence on influenza-like illness. In addition, the state influenza coordinator tracks the number of deaths due to pneumonia and influenza in Des Moines weekly as part of the 122-Cities Morbidity and Mortality reporting system sponsored by CDC.

Influenza and Other Respiratory Virus Weekly Activity Report, May 2, 2009 Week 17

Weekly report of the Iowa Influenza Surveillance Network produced by the Iowa Department of Public Health.

Influenza and Other Respiratory Virus Weekly Activity Report, April 25, 2009, Week 16

Weekly report of the Iowa Influenza Surveillance Network produced by the Iowa Department of Public Health.

Influenza and Other Respiratory Virus Weekly Activity Report, April 18, 2009, Week 15

Weekly report of the Iowa Influenza Surveillance Network produced by the Iowa Department of Public Health.

Influenza and Other Respiratory Virus Weekly Activity Report, April 11, 2009, Week 14

Weekly report of the Iowa Influenza Surveillance Network produced by the Iowa Department of Public Health.

Influenza and Other Respiratory Virus Weekly Activity Report, April 4, 2009, Week 13

Weekly report of the Iowa Influenza Surveillance Network produced by the Iowa Department of Public Health.

Influenza and Other Respiratory Virus Weekly Activity Report, March 28, 2009, Week 12

Weekly report of the Iowa Influenza Surveillance Network produced by the Iowa Department of Public Health.

Influenza and Other Respiratory Virus Weekly Activity Report, March 21, 2009, Week 11

Weekly report of the Iowa Influenza Surveillance Network produced by the Iowa Department of Public Health.

Influenza and Other Respiratory Virus Weekly Activity Report, March 14, 2009, Week 10

Weekly report of the Iowa Influenza Surveillance Network produced by the Iowa Department of Public Health.

Influenza and Other Respiratory Virus Weekly Activity Report, March 7, 2009, Week 9

Weekly report of the Iowa Influenza Surveillance Network produced by the Iowa Department of Public Health.

Influenza and Other Respiratory Virus Weekly Activity Report, February 28, 2009, Week 8

Weekly report of the Iowa Influenza Surveillance Network produced by the Iowa Department of Public Health.

Influenza and Other Respiratory Virus Weekly Activity Report, February 21, 2009, Week 7

Weekly report of the Iowa Influenza Surveillance Network produced by the Iowa Department of Public Health.