THE WEARING CHARACTERISTICS OF MINERAL AGGREGATES IN HIGHWAY PAVEMENTS
FIFTEEN ASPHALTIC CONCRETE AND SEVENTEEN PORTLAND CEMENT CONCRETE PAVEMENTS IN VIRGINIA WERE CHOSEN FOR STUDIES OF AGGREGATE WEAR AND RELATED WET PAVEMENT FRICTION. COARSE AGGREGATES FROM THIRTEEN DIFFERENT GEOLOGIC FORMATIONS AND QUARRY SOURCES HAD BEEN UTILIZED IN PAVEMENT CONSTRUCTION. FIELD MEASUREMENTS OF WET FRICTION AND PAVEMENT PROFILES AND LABORATORY STUDIES OF AGGREGATE PETROGRAPHY AND SURFACE MICROTEXTURE WERE EMPHASIZED. THE RESULTS SHOWED THAT AGGREGATES CAN BE CLASSIFIED INTO THREE CATEGORIES BASED ON THEIR RESPONSE TO THE WEARING STRESSES OF VEHICLE TIRES: (1) VERY HOMOGENEOUS AGGREGATES LACKING SIGNIFICANT ZONES AND PLANES OF WEAKNESS WEAR PREDOMINANTLY BY ABRASION; (2) AGGREGATES MARKED BY ZONES AND PLANES OF WEAKNESS WEAR PREDOMINANTLY BY DEGRADATION OR PARTICLE REMOVAL; AND (3) AGGREGATES OF INTERMEDIATE PHYSICAL STRUCTURE WEAR BY A COMBINATION OF ABRASION AND DEGRADATION. POLISHING IS MOST COMMON WITH AGGREGATES UNDERGOING ABRASION, THE RATE BEING DEPENDENT ON THE ABSOLUTE HARDENESS OF THE MINERAL CONSTITUENTS. POLISHING REMOVES MICROASPERITIES AND REDUCES THE ADHESION COMPONENT OF WET FRICTION. THE LOSS OF MACROTEXTURE, OR PAVEMENT RELIEF, IS COMMON WHERE DEGRADATION PREVAILS. THIS LOSS, IF EXCESSIVE, RETARDS WATER REMOVAL OR DRAINAGE AND ADVERSELY AFFECTS THE HYSTERESIS OR TIRE DEFORMATION COMPONENT OF PAVEMENT FRICTION. OPTIMUM WET FRICTION CONDITIONS ARE JUDGED TO PREVAIL WHEN A COMBINATION OF ABRASION AND DEGRADATION CREATES AN AGGREGATE SURFACE CONTAINING SIGNIFICANT ELEMENTS OF BOTH MACRO- AND MICROTEXTURE. IT IS CONCLUDED THAT CAREFUL PETROGRAPHIC STUDY OF AGGREGATE MINERALOGY AND TEXTURE WILL ALLOW A HIGH DEGREE OF PREDICTION OF THE RESULTING SURFACE CONFIGURATION AS AGGREGATES WERE UNDER TRAFFIC. /HSRI/
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Supplemental Notes:
- Vhrc 70-r7, 63 P, TABS, PHOTS, REF
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Corporate Authors:
Virginia Highway Research Council
Charlottesville, VA United States -
Authors:
- Webb, J W
- Publication Date: 1970-11
Subject/Index Terms
- TRT Terms: Asphalt concrete; Coarse aggregates; Concrete pavements; Durability; Durability tests; Friction; Geological surveying; Mineral aggregates; Moisture content; Pavements; Petrography; Polished aggregates; Portland cement concrete; Surface course (Pavements); Texture; Wear
- Uncontrolled Terms: Degradation; Wet conditions
- Old TRIS Terms: Petrographic investigations
- Subject Areas: Highways; Pavements;
Filing Info
- Accession Number: 00207365
- Record Type: Publication
- Source Agency: Highway Safety Research Institute
- Files: NTL, TRIS, ATRI
- Created Date: Aug 1 1971 12:00AM