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How to Perform AASHTO T283 Test for Moisture Damage of Asphalt Mixtures
Moisture damage is one of the major causes of pavement deterioration and failure. It occurs when water weakens the bond between the asphalt binder and the aggregate, resulting in stripping, rutting, cracking, and loss of strength. To prevent moisture damage, additives such as anti-stripping agents, hydrated lime, or portland cement can be used to improve the adhesion and cohesion of the asphalt mixture.
But how can you test the effectiveness of these additives and the resistance of your asphalt mixture to moisture damage? One of the most widely used methods is the AASHTO T283 test, also known as the Resistance of Compacted Asphalt Mixtures to Moisture-Induced Damage test. This test measures the change in tensile strength of compacted asphalt specimens after they are subjected to water saturation and accelerated water conditioning with a freeze-thaw cycle.
In this article, we will explain how to perform the AASHTO T283 test step by step, and what equipment and materials you will need. We will also provide a link to download a free PDF version of the AASHTO T283 standard for your reference.
What is AASHTO T283 Test?
AASHTO T283 is a standard method of test developed by the American Association of State Highway and Transportation Officials (AASHTO). It is used to evaluate the resistance of compacted asphalt mixtures to moisture-induced damage by measuring their tensile strength ratio (TSR).
The TSR is calculated by dividing the average tensile strength of three conditioned specimens by the average tensile strength of three control specimens. The conditioned specimens are saturated with water and subjected to one freeze-thaw cycle followed by a warm-water soaking cycle. The control specimens are tested without moisture conditioning.
The TSR indicates how much strength is retained by the asphalt mixture after exposure to moisture. A higher TSR means a higher resistance to moisture damage. AASHTO recommends a minimum TSR of 80% for asphalt mixtures used in pavements.
What Equipment and Materials Do You Need?
To perform the AASHTO T283 test, you will need the following equipment and materials:
- Vacuum container for saturating specimens
- Balance, general purpose class G2 (AASHTO M 231)
- Water bath, capable of maintaining a temperature of 140 Â 2ÂF (60 Â 1ÂC)
- Pans, having a surface area of 75-200 in2 (48,400 â 129,000) mm2 in the bottom and a depth of approximately 1 in. (25 mm)
- Loading jack and force measuring device
- Loading strips with a curved face to match the side of the specimen
- Forced-draft oven, capable of maintaining a temperature from room temperature to 350 Â 15ÂF (176 Â 3ÂC)
- Freezer, capable of maintaining a temperature of 0 Â 5ÂF (-18 Â 3ÂC)
- Plastic wrap and heavy-duty leak proof plastic bags
- 10 mL graduated cylinder
- Asphalt mixture samples
How to Perform AASHTO T283 Test?
The AASHTO T283 test consists of four main steps: sample preparation, moisture conditioning, tensile strength testing, and TSR calculation. Here is a summary of each step:
Sample Preparation
You will need to prepare at least six specimens from your asphalt mixture sample. The specimens should be 6 in. (150 mm) in diameter and 2.5 in. (63.5 mm) thick. You can use either laboratory-batched mixtures or field cores.
If you use laboratory-batched mixtures, you will need to mix enough material to produce at least eight specimens at the binder content recommended for the mixture. You will also need extra mixture for trials to establish the compaction required and for determining the maximum specific gravity of the mixture, if these values are not known. 51082c0ec5