45 Sand Seal ($$) A sand seal is a pavement preservation technique that involves the application of a quick-setting asphalt emulsion to the pavement surface, followed by a layer of fine aggregates, such as sand. This process provides a new wearing surface and can be used to fill small cracks and voids, improve skid resistance and protect the pavement structure by sealing the surface from the ingress of water and the effects of oxidation. The process typically follows these steps: 1. Surface Cleaning: The existing pavement surface is cleaned to remove any dust, debris and loose material to ensure proper bonding of the asphalt emulsion. 2. Asphalt Emulsion Application: A quick-setting asphalt emulsion is sprayed onto the pavement surface using specialized equipment. The type of emulsion used is selected based on the existing pavement conditions and the desired performance characteristics. 3. Sand Spreading: Immediately after the emulsion is applied, clean sand is spread over the surface. The sand should be of a specified gradation that allows it to embed into the emulsion without completely obscuring it. 4. Rolling: Once the sand is applied, it is rolled with pneumatic tire rollers to ensure good contact and adhesion between the sand and the asphalt emulsion. 5. Excess Sand Removal: After the emulsion has cured, any excess sand is removed from the surface, typically with a mechanical broom or air blower. The benefits of a sand seal include: • Improved Surface Texture: The fine aggregate provides a textured surface that can improve skid resistance and traction for vehicles. • Pavement Preservation: The seal serves as a barrier against moisture and sunlight, helping to slow down the oxidation of the asphalt binder. • Filling Minor Cracks: The combination of asphalt emulsion and sand can penetrate and fill small cracks in the pavement surface. • Cost-Effectiveness: Sand seals are relatively inexpensive compared to other surface treatments and can be a cost-effective method for maintaining low‑volume roads. Sand seals are typically used on low-traffic roads or as a part of a multi-layer surface treatment in combination with other seals. It is important to apply sand seals during warm, dry weather conditions to ensure proper curing of the asphalt emulsion.
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