51 Cape Seal ($$$$$) A cape seal is a two-step pavement preservation process that combines two surface treatments: a chip seal or scrub seal followed by a slurry seal or micro-surfacing. This method provides the benefits of both treatments, resulting in a smoother surface than a chip seal alone and adding structural integrity to the pavement system, thus extending the life of the pavement. Here’s a step-by-step explanation of the cape seal process: 1. Chip/Scrub Seal Application: The first step is applying a chip/scrub seal, which involves spraying asphalt emulsion onto the existing pavement surface and then immediately covering it with a layer of uniformly sized aggregate chips. The chips are then compacted into the emulsion to form an interlocked adhesive layer. 2. Curing of Chip Seal: The chip seal layer must cure for typically one to two weeks. This allows the emulsion to set properly and the aggregate to become firmly embedded in the binder. During this period, any loose chips are swept off the surface. 3. Slurry Seal or Micro-Surfacing Application: Once the chip/scrub seal has properly cured, a slurry seal or micro-surfacing layer is applied over the top. This second step involves spreading a mixture of fine aggregates, asphalt emulsion, water and additives over the surface. This layer fills any remaining voids and provides a smooth, durable wearing surface. 4. Curing of Final Surface: The slurry seal or micro-surfacing layer is then allowed to cure. The curing time is typically shorter than for the chip seal, often just a few hours. The benefits of a cape seal include: • Improved Surface Texture: The final slurry or micro-surfacing layer provides a smoother surface than the chip/scrub seal alone, enhancing ride quality. • Enhanced Durability: The combination of treatments results in a more durable surface that can better resist the effects of weathering and traffic. • Sealing Cracks: The cape seal process seals cracks in the pavement, reducing water infiltration that can cause further damage. • Cost-Effectiveness: Cape seals are more cost-effective than reconstructing or resurfacing with hot mix asphalt. • Extended Pavement Life: By combining treatments, cape seals can significantly extend the life of pavement surfaces. Cape seals are particularly effective on pavements with moderate to severe distress or where a chip/scrub seal alone would not provide a sufficiently smooth surface. They are suitable for both urban and rural roads, and the double-layer system is excellent for addressing issues like raveling, oxidation and loss of surface texture.
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