Transverse Cracking of Asphalt Pavements, HR-1040, Summary Report, 1982

This report summarizes the analysis of transverse cracking in asphalt pavement by a five state study team from Iowa, Kansas, Nebraska, North Dakota, and Oklahoma. The study was initiated under the sponsorship of the Federal Highway Administration and four evaluation conferences were held during the course of the study. Each state conducted a crack inventory on their asphalt pavement. An effort was made to correlate this inventory with numerous factors that were considered to be pertinent to the cracking problem. One state did indicate that there was a correlation between transverse cracking severity and the subsurface geology. The other states were unable to identify any significant factors as being the primary contributors. The analysis of the problem was divided into, (1) mix design, (2) maintenance, and (3) 3R rehabilitation. Many potential factors to be considered were identified under each of these three study divisions. There were many conclusions as to good and bad practices. One major conclusions was that a more effective crack maintenance program with early sealing was essential. Some new practices were suggested as potentially more cost effective in design, construction and maintenance. The interchange of methods and procedures by individual states yielded benefits in that other states selected practices that would be an improvement to their program.

Image Analysis for the Characterization of Materials for Highway Construction : Phase I, Progress Report, HR-346, 1992

The major objective of this project is to evaluate image analysis for characterizing air voids in Portland cement contract (PCC) and asphalt concrete (AC) and aggregate gradation in asphalt concrete. Phase 1 of this project has concentrated on evaluation and refinement of sample preparation techniques, evaluation of methods and instruments for conducting image analysis, and finally, analysis and comparison of a select portion of samples. Preliminary results suggest a strong correlation between the results obtained from the linear traverse method and image analysis methods for determining percent air voids in concrete. Preliminary work with asphalt samples has shown that damage caused by a high vacuum of the conventional scanning electron microscope (SEM) may too disruptive. Alternative solutions have been explored, including confocal microscopy and low vacuum electron microscopy. Additionally, a conventional high vacuum SEM operating at a marginal operating vacuum may suffice.

Be Aware of Scams Targeting Veterans, October 2, 2013

Scammers target vulnerable people through a variety of methods & exploit our emotions and values. Safeguard your personal information.

Current Population Reports Series P-26, Federal-State cooperative program for population estimates, July 1974

T his report presents population estimates for July 1, 1972 and provisional estimates for July 1, 1973, for counties and metropolitan areas prepared under the auspices of the Federal State Cooperative Program for Local Population Estimates. The objective of this program. is the development and publication of State - prepared estimates of the population of counties using uniform procedures largely standardized for data input and methodology. The methods used have been mutually agreed upon by the individual States and the Bureau of the Census on the basis of a test of methods against the 1970 census. For a more detailed description of the program.

Current Population Reports Series P-26, Federal-State cooperative program for population estimates, September 1975

This report presents population estimates for July 1, 1973 and provisional estimates for July 1, for counties and metropolitan areas prepared under the auspices of the Federal State Cooperative Program for Local Population Estimates. The objective of this program. is the development and publication of State - prepared estimates of the population of counties using uniform procedures largely standardized for data input and methodology. The methods used have been mutually agreed upon by the individual States and the Bureau of the Census on the basis of a test of methods against the 1970 census. For a more detailed description of the program.