ASTM C1604/C1604M-05 (R2019) PDF Download

ASTM C1604/C1604M-05 (R2019) is a standard test method that provides standardized procedures for obtaining and testing drilled cores of shotcrete. The test method is used to determine the compressive strength and splitting tensile strength of shotcrete in various stages, including pre-construction, construction, and older shotcrete structures. This method is particularly useful in situations where there is doubt about the quality of the in-place shotcrete due to low strength test results during construction or signs of distress in the structure.

The specimens obtained through this method are used for acceptance testing, construction control, and assessing the condition, quality, and uniformity of the shotcrete. They are also used to verify the thickness of shotcrete, assess shotcrete quality and workmanship, detect defects, evaluate shotcrete-to-substrate bond, and examine any reinforcement used in the shotcrete.

It is important to consider the location and orientation of the shotcrete in a structure as they can affect the shotcrete strength and core strength. Shotcrete strength may vary in vertical, sub-horizontal, and overhead elements, and core strength may be influenced by the orientation relative to the direction of shotcrete application.

The standard also highlights that shotcrete can be applied in different forms such as plain shotcrete, reinforced shotcrete, or fiber-reinforced shotcrete. However, core samples containing wire-mesh and reinforcing bars should not be used for compressive strength testing.

The moisture content of shotcrete can also influence its strength, so the standard includes a specified moisture conditioning procedure for the cores to minimize variations in moisture content during testing.

It is important to follow proper sampling procedures to ensure accurate and representative core samples. Care must be taken during core-drilling, sawing, and grinding to avoid adversely affecting the sample condition.

The standard also recommends establishing a sampling plan indicating the number and locations of samples. The acceptance criteria for shotcrete core strengths should be determined by the specifier of tests. The standard refers to additional references for guidance on sampling plans for concrete in constructions and core strength acceptance criteria.