AASHTO T85
Full Name
AASHTO T85 – Standard Method of Test for Specific Gravity and Absorption of Coarse Aggregate
Scope
AASHTO T85 is a standard test method used to determine the specific gravity and absorption of coarse aggregate, typically gravel or crushed stone, used in construction materials such as concrete and asphalt. Specific gravity is the ratio of the density of a material to the density of water, while absorption is the amount of water a material can absorb. These properties are crucial for mix design calculations, assessing aggregate quality, and predicting the behavior of the final product.
Key aspects of AASHTO T85:
- Purpose: the primary objectives of this test are to:
- Determine the bulk specific gravity (both dry and saturated-surface-dry) of coarse aggregate.
- Determine the apparent specific gravity of coarse aggregate.
- Calculate the absorption of coarse aggregate.
- Test procedure: the test involves weighing a sample of oven-dried coarse aggregate, then immersing it in water for a specific period (typically 15-19 hours). The sample is then surface-dried and weighed again to determine the saturated-surface-dry weight. Finally, the sample is weighed while suspended in water. The specific gravities and absorption are then calculated based on these measurements.
- Significance: specific gravity and absorption values are essential for several reasons:
- Mix design: they are used in mix design calculations to determine the proportions of aggregate, binder, and water needed to achieve the desired properties of concrete or asphalt.
- Quality control: these properties can indicate the presence of deleterious substances in the aggregate, such as lightweight or porous particles, which can negatively impact the performance of the final product.
- Durability: absorption can be an indicator of the aggregate’s durability and its potential to absorb water, which can affect the freeze-thaw resistance of concrete and the moisture susceptibility of asphalt.
Applications of AASHTO T85:
- Aggregate evaluation: this test is widely used by aggregate producers and construction contractors to assess the quality and suitability of coarse aggregates for various applications.
- Quality control: the specific gravity and absorption values are used as quality control parameters to ensure that the aggregates meet the specified requirements and standards.
- Research and development: the test is also used in research and development to investigate the properties of new aggregate materials and their potential applications in construction.
AASHTO T85 Accredited Laboratory
Applied Testing & Geosciences, LLC is accredited for performing tests using the AASHTO T85 standard.
Our laboratory offers comprehensive aggregate testing services, including the determination of specific gravity and absorption according to AASHTO T85. Our experienced technicians utilize calibrated equipment and adhere to standardized procedures to ensure accurate and reliable results for your construction projects.
Contact us for more information.
Resources
Keywords
specific gravity; absorption; coarse aggregate; bulk specific gravity; apparent specific gravity; saturated surface-dry; pycnometer; oven-dried; submerged weight