ASTM C805-02

Standard Test Method for Rebound Number of Hardened Concrete

SIGNIFICANCE AND USE
This test method is applicable to assess the in-place uniformity of concrete, to delineate regions in a structure of poor quality or deteriorated concrete, and to estimate in-place strength development.
To use this test method to estimate strength requires establishing a relationship between strength and rebound number. The relationship shall be established for a given concrete mixture and given apparatus. The relationship shall be established over the range of concrete strength that is of interest. To estimate strength during construction, establish the relationship by performing rebound number tests on molded specimens and measuring the strength of the same or companion molded specimens. To estimate strength in an existing structure, establish the relationship by correlating rebound numbers measured on the structure with the strengths of cores taken from corresponding locations. See ACI 228.1R4 for additional information on developing the relationship and on using the relationship to estimate in-place strength.  
For a given concrete mixture, the rebound number is affected by factors such as moisture content of the test surface, the method used to obtain the test surface (type of form material or type of finishing), and the depth of carbonation. These factors need to be considered in preparing the strength relationship and interpreting test results.
Different hammers of the same nominal design may give rebound numbers differing from 1 to 3 units. Therefore, tests should be made with the same hammer in order to compare results. If more than one hammer is to be used, perform tests on a range of typical concrete surfaces so as to determine the magnitude of the differences to be expected.
This test method is not intended as the basis for acceptance or rejection of concrete because of the inherent uncertainty in the estimated strength.
SCOPE
1.1 This test method covers the determination of a rebound number of hardened concrete using a spring-driven steel hammer.  
1.2 The values stated in SI units are to be regarded as the standard.  
1.3 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.

General Information

• Status: Historical
• Publication Date: 09-Jul-2002
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.64 - Nondestructive and In-Place Testing

Relations

• Replaces: ASTM C805-97 - Standard Test Method for Rebound Number of Hardened Concrete
• Effective Date: 10-Jul-2002
• Replaced By: ASTM C805/C805M-08 - Standard Test Method for Rebound Number of Hardened Concrete
• Effective Date: 01-Aug-2008
• Referred By: ASTM D4619-12(2018) - Standard Practice for Inspection of Linings in Operating Flue Gas Desulfurization Systems
• Effective Date: 10-Jul-2002
• Referred By: ASTM C856/C856M-20 - Standard Practice for Petrographic Examination of Hardened Concrete
• Effective Date: 10-Jul-2002
• Referred By: ASTM D6237-19 - Standard Guide for Painting Inspectors (Concrete and Masonry Substrates)
• Effective Date: 10-Jul-2002

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:C805–02
Standard Test Method for
1
Rebound Number of Hardened Concrete
This standard is issued under the fixed designation C 805; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope * poor quality or deteriorated concrete, and to estimate in-place
strength development.
1.1 This test method covers the determination of a rebound
5.2 To use this test method to estimate strength requires
number of hardened concrete using a spring-driven steel
establishing a relationship between strength and rebound
hammer.
number. The relationship shall be established for a given
1.2 The values stated in SI units are to be regarded as the
concrete mixture and given apparatus.The relationship shall be
standard.
established over the range of concrete strength that is of
1.3 This standard does not purport to address all of the
interest. To estimate strength during construction, establish the
safety concerns, if any, associated with its use. It is the
relationship by performing rebound number tests on molded
responsibility of the user of this standard to establish appro-
specimens and measuring the strength of the same or compan-
priate safety and health practices and determine the applica-
ion molded specimens. To estimate strength in an existing
bility of regulatory limitations prior to use.
structure, establish the relationship by correlating rebound
2. Referenced Documents
numbers measured on the structure with the strengths of cores
4
taken from corresponding locations. See ACI 228.1R for
2.1 ASTM Standards:
additional information on developing the relationship and on
C 125 Terminology Relating to Concrete and Concrete
2
using the relationship to estimate in-place strength.
Aggregates
5.3 For a given concrete mixture, the rebound number is
C 670 Practice for Preparing Precision and Bias Statements
2
affected by factors such as moisture content of the test surface,
for Test Methods for Construction Materials
the method used to obtain the test surface (type of form
E 18 Test Methods for Rockwell and Rockwell Superficial
3
material or type of finishing), and the depth of carbonation.
Hardness of Metallic Materials
These factors need to be considered in preparing the strength
3. Terminology
relationship and interpreting test results.
5.4 Differenthammersofthesamenominaldesignmaygive
3.1 Definitions:
rebound numbers differing from 1 to 3 units. Therefore, tests
3.1.1 For definitions of terms used in this test method, refer
should be made with the same hammer in order to compare
to Terminology C 125.
results.Ifmorethanonehammeristobeused,performtestson
4. Summary of Test Method
a range of typical concrete surfaces so as to determine the
magnitude of the differences to be expected.
4.1 A steel hammer impacts, with a predetermined amount
5.5 This test method is not intended as the basis for
of energy, a steel plunger in contact with a surface of concrete,
acceptance or rejection of concrete because of the inherent
and the distance that the hammer rebounds is measured.
uncertainty in the estimated strength.
5. Significance and Use
6. Apparatus
5.1 This test method is applicable to assess the in-place
6.1 Rebound Hammer, consisting of a spring-loaded steel
uniformity of concrete, to delineate regions in a structure of
hammer that when released strikes a steel plunger in contact
with the concrete surface. The spring-loaded hammer must
1
This test method is under the jurisdiction of ASTM Committee C09 on
travel with a consistent and reproducible velocity.The rebound
Concrete and ConcreteAggregates and is the direct responsibility of Subcommittee
C09.64 on Nondestructive and In-Place Testing .
Current edition approved July 10, 2002. Published August 2002. Originally
4
published as C 805 – 75 T. Last previous edition C 805 – 97. ACI 228.1R-95, “In-Place Methods to Estimate Concrete Strength,” ACI
2
Annual Book of ASTM Standards, Vol 04.02. Manual of Concrete Practice-Part 2, 2000, American Concrete Institute, 38800
3
Annual Book of ASTM Standards, Vol 03.01. Country Club Drive, Farmington Hills, MI 48331.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
C805–02
surface for 24 h prior to testing. In cases of a thick layer of carbonated
distanceofthesteelhammerfromthesteelplungerismeasured
concrete, it may be necessary to remove the carbonated layer
...