Crushed Stone Granular Surfacing Materials, HR-2046 and MLR-90-07, 1990

(1990) Crushed Stone Granular Surfacing Materials, HR-2046 and MLR-90-07, 1990. Transportation, Department of


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This project included the following tasks: (1) Preparation of a questionnaire and survey of all 99 Iowa county engineers for input on current surfacing material practice; (2) County survey data analysis and selection of surfacing materials gradations to be used for test road construction; (3) Solicitation of county engineers and stone producers for project participation; (4) Field inspection and selection of the test road; (5) Construction of test road using varying material gradations from a single source; and (6) Field and laboratory testing and test road monitoring. The results of this research project indicate that crushed stone surfacing material graded on the fine side of Iowa Department of Transportation Class A surfacing specifications provides lower roughness and better rideability; better braking and handling characteristics; and less dust generation than the coarser gradations. It is believed that this material has sufficient fines available to act as a binder for the coarser material, which in turn promotes the formation of tight surface crust. This crust acts to provide a smooth riding surface, reduces dust generation, and improves vehicle braking and handling characteristics.

Item Type: Departmental Report
Keywords: Aggregate gradation, Braking performance, County roads, Crushed rock, Driving, Dust control, Experimental roads, Fines (Materials), Handling characteristics, Materials, Natural earth crust materials, Ride quality, Roughness, Specifications, Surface course (Pavements)
Subjects: Transportation > Pavements
Transportation > Materials
Transportation > Roads and highways
Transportation > Design and Construction
Transportation > Maintenance and preservation
ID Code: 19899
Deposited By: Iowa DOT Library
Deposited On: 24 Jun 2015 17:04
Last Modified: 29 Jun 2015 17:05