What Is 9.5 Mm Superpave in GDOT?

The Georgia Department of Transportation (GDOT) utilizes various pavement technologies to ensure efficient and long-lasting road infrastructure. With careful consideration of these components, GDOT aims to deliver safe and reliable roadways that withstand the test of time and provide optimal driving experiences for all road users.

What Is the Maximum Aggregate Size for Superpave?

What Is 9.5 Mm Superpave in GDOT?

The term “9.5 mm” refers to the maximum aggregate size, indicating that the largest individual stone in the mix shouldn’t exceed 9.5 millimeters in diameter.

Superpave is a mix design method developed by the Strategic Highway Research Program (SHRP) to improve the durability and performance of asphalt pavements. It takes into account various factors, such as traffic volume, climate conditions, and material properties, to design a mix that will resist rutting, cracking, and other distresses.

Standard Superpave aggregate rock sizes range from 2 inches to minus #200 fines. These sizes are determined by the sieves used in the Superpave grading system. The sieve sizes range from 2-inch (50 mm) to #200 (0.075 mm), allowing for a wide range of aggregate sizes to be included in the mix.

For Superpave base courses in GDOT, the typical rock sizes used are 1.5 inches or 1 inch. These sizes are smaller than the maximum aggregate size of 9.5 mm, which allows for a more compact and dense mix that provides better stability and load-bearing capacity.

Factors such as traffic volume, pavement thickness, and climate conditions will determine the appropriate aggregate size for the base course. The goal is to achieve a strong and durable pavement that can withstand the expected traffic loads and environmental conditions.

It’s essential to consider all aspects of the pavement design, including aggregate gradation, binder type, and compaction requirements, to ensure the long-term performance and durability of the pavement.

Factors Affecting Aggregate Size Selection in Superpave Mix Design

In Superpave mix design, the selection of aggregate size is crucial and influenced by various factors. The key considerations include the traffic volume, environmental conditions, and pavement structure. Each of these factors plays a significant role in determining the appropriate aggregate size for the mix.

Firstly, the traffic volume is an important consideration as it determines the level of stress the pavement will experience. Higher traffic volumes require a stronger and more durable mix, which typically necessitates the use of larger aggregate sizes.

Secondly, environmental conditions such as temperature and moisture also impact the selection of aggregate size. In colder climates, smaller aggregate sizes are preferred to ensure better interlocking and resistance to freeze-thaw cycles. Conversely, in warmer regions, larger aggregate sizes are typically used to prevent rutting and deformation.

Lastly, the pavement structure itself affects the choice of aggregate size. The aggregate must be able to provide sufficient strength and stability to support the load and distribute it evenly across the pavement layers. Factors such as the thickness of each layer and the type of binder used influence the selection of aggregate size.

By considering these factors, the Georgia Department of Transportation (GDOT) can determine the most suitable aggregate size for it’s Superpave mix design. The aim is to achieve optimal performance, longevity, and safety for the roadways while considering the specific conditions and requirements of the region.


This type of mixture is carefully designed to meet certain performance requirements, such as durability, resistance to rutting and cracking, and optimal skid resistance. The 9.5 mm Superpave mix incorporates a specific aggregate size that contributes to it’s overall performance. As technology advances, the use of Superpave mixtures continues to evolve, providing improved road surfaces that enhance the overall driving experience and promote transportation efficiency. Thus, understanding the significance of 9.5 mm Superpave in GDOT enables informed decision-making in road construction and maintenance projects.

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