Answer :
Final answer:
The correct ASTM method for obtaining a concrete sample is ASTM C31, which focuses on making and curing concrete test specimens in the field, ensuring accurate assessment of concrete's characteristics. The correct option is b) ASTM C31.
Explanation:
The ASTM C31 method is the correct procedure for obtaining a concrete sample. This standard is specifically designed for making and curing concrete test specimens in the field. It addresses the procedures for collecting concrete samples from fresh concrete and details how these samples should be made, stored, and cured for testing purposes.
It's essential to ensure that the test results accurately reflect the concrete's characteristics as used in a project, allowing for proper assessment of the concrete's strength and durability. In contrast, ASTM D143 pertains to the testing of small clear specimens of timber, ASTM E329 deals with standards for agencies performing construction material engineering and testing services, and ASTM A36 specifies the properties of structural steel.