Significance and Use

These test methods are useful as rapid, nondestructive techniques for the in-place determination of the density of unhardened concrete. The backscatter test method is also useful for the same purpose on hardened concrete. The fundamental assumptions inherent in the test methods are that Compton scattering is the dominant interaction and that the material under test is homogeneous.

These test methods are suitable for control and for assisting in acceptance testing during construction, for evaluation of concrete quality subsequent to construction, and for research and development.

Note 1Care must be taken when using these test methods in monitoring the degree of consolidation, which is the ratio of the actual density achieved to the maximum density attainable with a particular concrete. The test methods presented here are used to determine the actual density. A density measurement, by any test method, is a function of the components of the concrete and may vary, to some extent, in response to the normal, acceptable variability of those components.

Test results may be affected by reinforcing steel, by the chemical composition of concrete constituents, and by sample heterogeneity. The variations resulting from these influences are minimized by instrument design and by the user's compliance with appropriate sections of the test procedure. Results of tests by the backscatter test method may also be affected by the density of underlying material. The backscatter test method exhibits spatial bias in that the apparatus's sensitivity to the material under it decreases with distance from the surface of the concrete.

Note 2Typically, backscatter gauge readings represent the density in the top 75 to 100 mm [3 to 4 in.] of material.

1. Scope

1.1 These test methods cover the determination of the in-place density of unhardened and hardened concrete, including roller compacted concrete, by gamma radiation. For notes on the nuclear test see Appendix X1.

1.2 Two test methods are described, as follows:

1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

C29/C29M Test Method for Bulk Density (Unit Weight) and Voids in Aggregate

C138/C138M Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete

C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials

Keywords

acceptance testing; backscatter measurement; concrete-density; density; direct transmission measurement; gamma radiation; in-place density; nuclear testing ; roller-compacted concrete; Backscattering analysis; Density--concrete; Direct transmission method; Gamma radiation; Hardened concrete; Nondestructive evaluation (NDE)--concrete/masonry; Nuclear methods; Quality control (QC)--cement/concrete/masonry/aggregates; Unhardened concrete;

ICS Code

ICS Number Code 91.100.30 (Concrete and concrete products)

DOI: 10.1520/C1040_C1040M-08

ASTM International is a member of CrossRef.

ASTM C1040 / C1040M