Performance of Chip Seals Using Local and Minimally Processed Aggregates for Preservation of Low Traffic Volume Roadways.

摘要

This report documents the performance of two low traffic volume experimental chip seals constructed using locally available, minimally processed sand and gravel aggregates after four winters of service. The projects were constructed by CDOT maintenance personnel during the summer of 2009 using two sources of aggregate. These aggregates consisted of locally available products representing (1) materials routinely utilized and (2) materials that were marginal with respect to aggregate gradation and crushing requirements. An objective of this work was to evaluate the feasibility and cost/benefit of using aggregates in chip seals of lower quality than normally used with respect to gradation on low volume roadways. Because the cost of transporting high quality aggregates from front range sand and gravel and quarry locations to the eastern regions of Colorado is high and much of the pavement preservation activities in eastern Colorado are on low volume roadways, utilizing locally available aggregates would provide economic benefits if acceptable performance were demonstrated. After four winters and three summers service both experimental chip seals are performing well. Condition surveys of each pavement were conducted after each winter and summer to document pavement condition. Results indicate that pavement distress is in the form of longitudinal and transverse cracking and localized flushing due to non-uniform asphalt emulsion application during construction. Based on results from the last condition survey, both test pavements should perform acceptably for the next several years assuming no significant change in traffic levels. No significant differences were measured in performance for any of the evaluation sections.Implementation It appears that locally available, minimally processed aggregates can be successfully applied as chip seal aggregate on low volume roadways.