Evaluation of Oklahoma pavement design procedure - compendium of informations (84-60)

Final Report July 78 to March 83N

Pavement Recycling Guidelines for Local Governments - Reference Manual: Appendices

DTFH61-85-C-00118Recycling processes can be categorized according to material type - asphalt surface recycling, cold-mix asphalt recycling, hot-mix asphalt recycling, and portland cement concrete recycling; or according to procedural type - surface recycling, in-place recycling and central plant recycling. If the project can be restored by making corrections to the surface, with a minimum of new materials, surface recycling will prove satisfactory. If substantial corrections are required, in-place or central plant mixed procedures should be used. Methods of mix design and structural design for pavements containing recycled materials are generally similar to those used for designing mixes containing all virgin materials. The major difference is that variability in the properties of the recycled materials needs to be taken into consideration. This necessitates more frequent sampling and testing than with conventional mixtures and greater engineering judgment on the part of the designer. Cost is the traditional criterion for selection between various rehabilitation alternatives. The alternative with the least cost, including initial and maintenance, is usually selected by the designer. In the case of recycling, the relative cost savings will depend on the costs and availability of other types of treatment, as well as those of the recycling option selected

Improved Methods and Equipment to Conduct Pavement Distress Surveys

DTFH61-85-C-001This report documents the second phase of an FHWA study, entitled "Pavement Condition Monitoring Methods and Equipment". In this phase selected distress survey methods and devices, representing a range in automation, were tested from July to September 1986. The following methods and devices were included in the testing: manual mapping, detailed visual surveys using manual recording and automatic data logging, PASCO ROADRECON survey vehicle, the GERPHO survey vehicle, the ARAN survey vehicle, and the Laser RST survey vehicle. The field tests were conducted on flexible, rigid, and composite pavements exhibiting a range of pavement distresses. The survey devices were evaluated using performance, capability, efficiency, and cost-effectiveness criteria. The study concluded that, at present, the GERPHO and PASCO ROADRECON are best suited for pavement performance research studies due to factors such as the permanent film record, cost-effectiveness, and data quality. The GERPHO and PASCO ROADRECON are also judged to be suitable for network and project level surveys. The ARAN and Laser RST were recommended for consideration for use in network level surveys for pavement management. It is also recommended that data loggers be used to record field data for traditional manual survey techniques

Impact of Truck Characteristics on Pavements: Truck Load Equivalency Factors

DTFH61-87-C-00120Truck load equivalency factors relate vehicle axle loads to pavement damage and life. They provide a method to convert the effects of mixed traffic to a standard loading condition. Equivalent loadings for most pavement design and evaluation procedures are currently predicted using the AASHTO method of equivalency factors. This study was undertaken to evaluate various types of primary pavement response derived load equivalency factors. These use pavement response measurements such as strain and deflection to estimate the equivalent damaging effect of any axle loading condition. These types of factors are also expressed in terms of a relative number of equivalent standard axle loads. A number of primary response equivalency factor methods were evaluated and several selected for further study. Deflection and strain pavement response measurements were evaluated over an experimental factorial of axle type, axle load, tire pressure, speed, pavement thickness, and pavement temperature. Primary response load equivalencies were calculated using the selected methods and a number of statistical comparisons were made. Results of the study indicate that the concept of primary response truck load equivalency factors is viable and can be extremely useful for estimating load equivalence for pavement design and research purposes. Results also indicate which of the vehicle and pavement factors studied most significantly effect the estimate of load equivalency. Recommendations are also made for use of primary response load equivalencies and for further research into the subject