Field Testing of Asphaltic Concrete Mixes, HR-101 and R-183, 1968

The amount of asphalt cement in asphaltic concrete has a definite effect on its durability under adverse conditions. The expansion of the transportation system to more and heavier loads has also made the percentage of asphalt cement in a mix more critical. The laboratory mixer does not duplicate the mixing effect of the large pugmills; therefore, it is impossible to be completely sure of the asphalt cement needed for each mix. This percentage quite often must be varied in the field. With a central testing laboratory and the high production of mixing plants today, a large amount of asphaltic concrete is produced before a sample can be tested to determine if the asphalt content is correct. If the asphalt content lowers the durability or stability of a mix, more maintenance will be required in the future. The purpose of this project is to determine the value of a mobile laboratory in the field, the feasibility of providing adequate, early testing in the field, and correlation with the central laboratory. The major purpose was to determine as soon as possible the best percentage of asphalt.

Evaluation of the PAVEDEX Road Survey System in Iowa, HR-547, 1990

The Iowa Department of Transportation (DOT) evaluated the PAS I Road Survey System from PAVEDEX, Inc. of Spokane, Washington. This system uses video photograph to identify and quantify pavement cracking and patching distresses. Comparisons were made to procedures currently used in the State. Interstate highway, county roads and city streets, and two shoulder sections were evaluated. Variables included travel speeds, surface type and texture, and traffic control conditions. Repeatability and distress identification were excellent on rigid pavements. Differences in distress identification and the effect of surface textures in the flexible test sections limited the repeatability and correlation of data to that of the Iowa DOT method. Cost data indicates that PAVEDEX is capable of providing comparable results with improved accuracy at a reasonable cost, but in excess of that experienced currently by the Iowa DOT. PAVEDEX is capable of providing network level pavement condition data at highway speeds and analysis of the data to identify 1/8-inch cracks at approximately 2-3 lane miles per hour with manual evaluation. Photo-logging capability is also included in the unit.

Field Evaluation of Electro-Reflective Measuring Apparatus (ERMA), MLR-81-01, 1981

The Electro-Reflective Measuring Apparatus (ERMA) was developed by the Minnesota Department of Highways in 1974 to measure the retro-reflective characteristics of pavement marking materials. Minnesota researchers recommended that due to the increased cost of pavement marking materials and reduced availability of these materials, ERMA can and should be used as a maintenance management tool to determine when painting is necessary rather than according to a fixed time schedule. The Iowa DOT Office of Materials built an ERMA device patterned after Minnesota's design in 1976. Subsequent efforts to calibrate and correlate this ERMA device to District Paint Foremen ratings proved unsuccessful, and ERMA modification or abandonment was recommended in 1979. Lyman Moothart, Materials Lab. Tech. 4, modified the ERMA device in 1980 and correlation attempts to District Paint Foremen ratings conducted in November 1980 have been moderately successful. A Paint/No Paint ERMA value has been established which will identify about 90% of the painting needs but will also include about 40% of the marking lines not needing repainting. The Office of Maintenance should establish a trial ERMA program to study the accuracy and potential cost savings of using ERMA to identify pavement marking needs.