| Abstract: | Seal coats are a very important preventive maintenance method used throughout Texas. Through the preventive maintenance program, about 16,000 lane miles a year are routinely resurfaced with a seal coat by contracts and about 3,000 lane miles per year of seal coats are placed with state forces. Additionally, seal coats are used in intermediate layers during construction to seal the pavement structure. This is a significant investment of over $300 million annually. For more than 40 years, there has been little change in the design and construction practices, including equipment used to place the asphalt or aggregate. With little to no changes in design and construction methods, Texas continues to see the same problems, such as rock loss, flushing, and bleeding reoccurring. New technologies are being developed that could potentially reduce these types of problems. There have been recent new developments for asphalt distributors due to the performance-based warranty specification being used by the New Zealand Transport Agency. The asphalt distributor improvements include the ability to use up to eight different transversely varying application rates at normal operating speed. This is extremely useful to apply the optimal shot rate when surface conditions change. In addition to this, high definition video systems and scanners can map and document existing texture conditions to define the required spray bar pattern. |
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