ASTM C231
Full Name
ASTM C231 – Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method
Scope
ASTM C231 outlines the procedure for determining the air content of freshly mixed concrete using a pressure meter. This method is based on Boyle’s Law, which states that the pressure of a gas is inversely proportional to its volume at a constant temperature.
The scope of ASTM C231 includes:
- Types of concrete: the standard covers all types of concrete, except those containing lightweight aggregates.
- Principle: the method involves applying a known pressure to a sample of concrete in a sealed container. The air in the concrete compresses, causing a change in pressure within the container. This change in pressure is measured and used to calculate the air content.
- Apparatus: it specifies the apparatus required, including a pressure meter, a measuring bowl, a cover assembly, a hand pump, and a calibration vessel.
- Calibration: it provides instructions for calibrating the pressure meter and determining an aggregate correction factor.
- Procedure: it details the step-by-step procedure for conducting the test, including mixing the concrete, placing it in the measuring bowl, sealing the bowl with the cover assembly, applying pressure with the hand pump, and reading the pressure gauge to determine the air content.
- Calculations: it provides formulas for calculating the air content based on the pressure readings and the aggregate correction factor.
- Precision and bias: it provides information on the precision and bias of the test method.
ASTM C231 does not cover:
- Lightweight aggregate concrete: the method is not suitable for concrete containing lightweight aggregates due to the presence of entrapped air within the aggregate particles.
- Alternative pressure methods: the standard focuses on a specific pressure method and does not cover other variations or modifications of the pressure method.
Overall, ASTM C231 is a widely used and recognized standard for measuring the air content of freshly mixed concrete. It is essential for quality control in concrete production and construction, as the air content significantly affects the concrete’s properties, such as workability, strength, durability, and resistance to freeze-thaw cycles.
ASTM C231 Accredited Laboratory
Applied Testing & Geosciences, LLC is accredited for performing tests using the ASTM C231 standard.
Contact us today to learn more about our testing capabilities and how we can support your business.
Resources
Keywords
air content; pressure method; freshly mixed concrete; pressure meter; aggregate correction factor; calibration; measuring bowl; cover assembly