ASTM C457/C457M − 12 Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete

Scope of ASTM C457/C457M − 12 Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete

1.1 This test method describes procedures for microscopical determinations of the air content of hardened concrete and of the specific surface, void frequency, spacing factor, and pasteair ratio of the air-void system in hardened concrete (1).2 Two procedures are described:

1.1.1 Procedure A, the linear-traverse method (2, 3).

1.1.2 Procedure B, the modified point-count method (3, 4, 5, 6).

1.2 This test method is based on prescribed procedures that are applied to sawed and lapped sections of specimens of concrete from the field or laboratory.

1.3 It is intended to outline the principles of this test method and to establish standards for its adequate

performance but not to describe in detail all the possible variations that might be used to accomplish the objectives of this test method.

Significance and Use of ASTM C457/C457M − 12 Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete

5.1 The parameters of the air-void system of hardened concrete determined by the procedures described in this test method are related to the susceptibility of the cement paste portion of the concrete to damage by freezing and thawing.

Hence, this test method can be used to develop data to estimate the likelihood of damage due to cyclic freezing and thawing or to explain why it has occurred.

The test method can also be used as an adjunct to the development of products or procedures intended to enhance the resistance of concrete to cyclic freezing and thawing (1).