Detecting Flushing of Thin-Sprayed Seal Pavements Using Pavement Management Data

Abstract

Flushing is a pavement surface defect that affects the structural integrity of thin-sprayed seal (chip seal) surfacings. Analysis was carried out on pavement performance data to determine the combination of factors that provides the best indication of flushing occurrence on in-service pavements. Data were sourced from the Long-Term Pavement Performance (LTPP) programme in New Zealand as well as from field testing. The LTPP data were analysed in four categories; pavement composition characteristics: traffic-related factors, climatic factors, and effects of other pavement defects. Factor and correlation analyses were used to determine and investigate the factors that showed significant relationships to flushing. Surface thickness, surface age, surfacing type, and rutting were found to have statistically significant correlations to flushing. Field testing provided data relating to the soil moisture environment under the pavement. The dry density and water content of soil were identified as having significant correlations to flushing. Regression analysis of the combination of these factors yielded a robust model to identify flushing.