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Road Pavement - distress - discussion

Distresses in Flexible Pavement Background Pavement typically experiences distresses such as cracking and deformation over time, which are anticipated during design. Regular monitoring and repair are necessary to maintain service quality. When distress levels exceed predefined thresholds, rehabilitation becomes essential. This section explores various distresses, their causes, and mitigation strategies. Major Distresses The analysis and design of flexible pavement focus on four primary distresses: Alligator Cracking: Characterized by interconnected cracks resembling a chicken wire pattern, originating from tensile strain due to repeated loading. Full-depth rehabilitation is recommended for severe instances, while partial repairs can defer damage in low-severity cases. Top-Down Longitudinal Cracking: Cracks parallel to the roadway centerline initiated by surface strain. Treatment options include asphalt replacement or full-depth rehabilitation depending on crack severity. Rutting: Longitudinal depressions in the wheel path caused by permanent deformation. Rutting can be classified as structural or shear deformation. Treatment involves milling and replacing with rut-resistant materials if depth exceeds ¾ inch. Transverse Cracking: Cracks perpendicular to the pavement due to thermal cycles, with two types: thermal fatigue and low-temperature cracking. Treatment varies based on depth, ranging from thin replacement to full-depth repairs. Minor Distresses In addition to major distresses, several minor distresses are identified: Stripping: Moisture-related damage that affects bond between aggregates and asphalt, typically requiring full-depth reclamation for repair. Raveling: Loss of binder leading to debris and rough surfaces, addressed through patching or overlays. Potholes: Bowl-shaped depressions caused by various factors, repaired through patching techniques. Bleeding: Surface flushing of asphalt binder, corrected by applying coarse materials or resurfacing. Block Cracking: Interconnected rectangular cracks due to asphalt shrinkage, treated with crack sealing or overlays. Reflection Cracking: Cracks in overlays reflecting underlying pavement defects, addressed through sealing or replacement. Depression: Localized lower elevations from subgrade failure, treated by excavation and replacement. Corrugation and Shoving: Surface waves due to traffic action, repaired with patches or overlays. Slippage Cracking: Crescent-shaped cracks caused by poor bonding, requiring removal and replacement. Microcracking: Small cracks from compaction issues, treated with overlays or micro-surfacing. Water Bleeding and Pumping: Issues with water seeping through cracks, requiring drainage improvements or sealing. Polished Aggregate: Loss of aggregate texture reducing skid resistance, corrected with slurry seals. Mat Tearing: Surface defects during paving, addressed with overlays. Nonuniform Texture: Variations in surface appearance needing treatment with overlays. Miscellaneous Distresses Other less common distresses include edge cracks, lane/shoulder drop-offs, and problems related to base/subgrade conditions. Surface waves and joint separations are also noted as potential issues. Summary Discussion for various distresses encountered in asphalt pavements, emphasizing the need for tailored treatment strategies based on local conditions and practices. Multiple causes for these distresses exist, and coordinated repair strategies are essential for effective pavement management...