Stone mastic asphalt (SMA), also referred to as stone-matrix asphalt originated in

Germany during the 1960s. It serves as a durable and resilient surface material,

particularly suitable for heavily traveled roads. SMA has gained popularity in

various regions including Europe, Australia, the United States, and Canada, where

it is favored or used on residential streets and highways.

Stone Mastic Asphalt presents a robust solution for road surfacing, delivering superior performance and longevity in demanding environments.

• Durable Surface Texture: SMA provides a textured and durable surface that resists rutting, ensuring long-lasting performance and reduced maintenance needs.
• Noise Reduction: The surface texture of SMA results in lower traffic noise compared to Dense Graded Asphalt (DGA), akin to Open Graded Asphalt (OGA).
• Compatibility with Equipment: SMA can be produced and compacted using existing plants and equipment for normal hot mix, with minimal adjustments.

• Suitability for High-Traffic Areas: SMA can be used at intersections and other high-traffic locations where OGA may not be suitable.
• Reduced Cracking: SMA surfacings may reduce reflection cracking from underlying cracked pavements due to the flexible mastic.
• Enhanced Durability: SMA exhibits durability equivalent to or greater than DGA, and significantly superior to OGA.

The composition of SMA consists primarily of coarse aggregate, which forms a robust stone skeleton that effectively resists permanent deformation. This stone skeleton is then infused with a mixture of bitumen and filler, supplemented with fibers to bolster bitumen stability and prevent binder drainage during transport and application. A standard SMA blend typically comprises:

• 70−80% coarse aggregate
• 8−12% filler
• 6.0−7.0% binder
• 0.3% fiber

Moreover, the fibers exhibit strong absorption properties, enabling them to fully absorb bitumen within the mixture and tightly adhere to the bitumen surface. This results in increased bitumen content and a thicker bitumen layer, enhancing the aging resistance and significantly prolonging the service life of the bitumen layer. Additionally, the fibers possess easy dispersibility, ensuring uniform distribution with a brief pre-mixing duration of 5-15 seconds. This characteristic prevents the formation of micelles in the mixture, contributing to overall asphalt quality and performance.