Browsing by Author "Kim, Jong Ryeol"
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Item Low Volume Road Pavement Design: A Review of Practice in the Upper Midwest(1991-08) Newcomb, Dave; Kim, Jong RyeolThe objective of this report is to present a synthesis of low volume road pavement design with an emphasis on how it is practiced in the Upper Midwest of the United States. Several low volume road design methods are presented representing a range in approaches from empirical to mechanistic-empirical. The design procedures presented will also vary from those globally applicable to those which were developed for specific climatic regions. Finally, a review of local design practice in Minnesota will be given. Factors in pavement design are materials (subgrade, subbase and base), environment (temperature, frost and rainfall) and traffic.Item Polymerized Crumb Rubber Modified Mixtures in Minnesota(1994-01) Newcomb, Dave; Stroup-Gardiner, Mary; Kim, Jong Ryeol; Allen, Bruce; Wattenhoffer-Spry, JeffThis research program was based on laboratory and field studies. All work was limited to the use of a 10-mesh crumb rubber in the dry process. An evaluation of the asphalt-rubber interactions indicated that there should be a reasonable level of interaction between the crumb rubber and the asphalt cement selected for the project. A suggested criterion for defining an acceptable level of interaction would be to establish a minimum viscosity of 15 Poise (Brookfield viscosity) for a neat asphalt cement modified with 20 percent crumb rubber. When designing a crumb rubber modified mixture, the aggregate gradation should be substantially gapped. The target gradation used in the construction of the Babbit, Minnesota test sections should be considered as a guideline for an acceptable gapped gradation. Stockpile gradations should be adjusted for crumb rubber gradations volumetrically; generally, 1 gram of crumb rubber occupies the same volume as 3 grams of aggregate for a given sieve size. The optimum asphalt content for CRM mixtures should be based on air voids from 1.5 to 3 percent. During construction, the crumb rubber (supplied in 50 Ibs. bags) should be added through the recycled asphalt (RAP) hopper (drum plant) or directly into the pug mill (batch plant). Laydown and compaction procedures should proceed as usual. Use of vibration on the rollers should be used at the discretion of the field engineer.