Published: 2014
Total Pages: 184
Get eBook
Slurry seals and micro-surfacing (slurry surfacing systems) are widely used in pavement maintenance programs as primary surface treatments for extending pavement life and restoring serviceability function of structurally adequate pavements. Compared to hot mix asphalt overlay, these treatments are more cost-effective, energy-efficient, and environmentally friendly. In order to be effective, a rational mixture designed must be carried out to determine mixture components and proportions to be used in the field. In spite of their widespread use, mixture design and testing methodologies for slurry surfacing systems are still lacking. Current design practices and testing procedures are based on the art and experience of the contractor, and checked with tests with no known relation to field performance. The main objective of this study is to develop an improved the mixture design framework and testing methodologies for slurry surfacing system. Candidate test methods for evaluating critical mixture performance parameters related to common field distresses were evaluated in the laboratory, and modified as needed. This included test for workability, early raveling, and moisture induced raveling, bleeding and rutting. Promising candidate test methods were selected based on repeatability, sensitivity to design factors, simplicity, and cost. A unified mixture design framework for both slurry seals and micro-surfacing that incorporates the candidate test methods was developed. It allows the optimum emulsion content to be selected based on minimizing moisture induced raveling and bleeding. The mixture design procedure developed was verified with design parameters from field projects around the country. The results showed that the developed procedure yield design parameters similar to those used in the field. This finding is promising given that current mixture design practices rarely give design parameters in agreement with those known by contractors to give satisfactory field performance. It is recommended that the modified mixture design procedures developed in this study be adapted as an initial basis for developing a standardized mixture design framework for slurry surfacing systems. Additional materials need to be tested to ensure that the procedure is applicable to common materials used. Finally, evaluation of field projects is needed to establish performance limits.