Stone Mastic Asphalt (SMA)

Stone Mastic Asphalt (SMA) is a specialized asphalt mixture characterized by a discontinuous gradation, a higher amount of coarse aggregate, mineral filler, bitumen, and cellulose fiber.

Composition and Design

High Coarse Aggregate Content: The mixture contains a high quantity of coarse aggregate, resulting in a significant amount of voids between the aggregates.
Filling Voids: These voids are filled with fine aggregate, filler, bitumen, and cellulose fiber (HiperCell). The discontinuous gradation leads to a higher content of filler and bitumen, earning the name "stone" and "mastic" due to its composition.

Enhancing Asphalt Stripping Resistance

Stripping resistance-enhancing additives, also known as DOP (Dilution of Oils), create a stronger bond between bitumen and aggregate. The use of TeraGrip Stripping Preventive Additive, developed by İstanbul Teknik, extends the lifespan of asphalt roads with a minimal additional cost compared to the total asphalt material cost.

Characteristics of Stone Mastic Asphalt (SMA)

High Coarse Aggregate Content: This feature enhances the load-bearing capacity due to increased stone-to-stone contact.
High Filler Content: The presence of significant filler contributes to the overall performance of the asphalt.
Polymer Modified Bitumen: SMA typically includes a higher proportion of polymer-modified bitumen, enhancing its properties.
HiperCell (Cellulose Fiber): The inclusion of cellulose fiber further improves the mixture's characteristics.

Advantages of Stone Mastic Asphalt (SMA)

Increased Load-Bearing Capacity: The higher quantity of coarse aggregate results in greater stone-to-stone contact, providing a higher load-bearing capacity compared to Dense Graded Asphalt (DGA).
High Abrasion Resistance: The use of basalt or other high-silica aggregates contributes to excellent abrasion resistance.
Better Surface Texture and Skid Resistance: Studies have shown that SMA has superior surface texture and skid resistance compared to DGA.
Thermal and Fatigue Crack Resistance: Due to its higher polymer-modified bitumen content, SMA is more resistant to thermal and fatigue cracking.
Quiet and Comfortable Ride: The mastic structure allows for a quieter and more comfortable driving experience.
Reduced Hydroplaning Risk: While generally accepted that dry surfaces rarely pose skid resistance issues, once wet, surface properties can significantly change. SMA shows less tendency for hydroplaning in wet conditions.

Application Areas of Stone Mastic Asphalt (SMA)

Roads with Heavy Vehicle Loads: Ideal for roads that experience high traffic volumes.
Thin Asphalt Layers: Can be applied in thin asphalt layers (2-3 cm).
Wearing Course on Steel Bridges: Used as a wearing course over mastic asphalt on steel bridges.