ASTM C918-97e1

Standard Test Method for Measuring Early-Age Compressive Strength and Projecting Later-Age Strength

SCOPE
1.1 This test method covers a procedure for making, curing, and testing specimens of hardened concrete at early ages. The specimens are stored under standard-curing conditions and the measured temperature history is used to compute a maturity index that is related to strength gain.  
1.2 This test method also covers a procedure for using the results of early-age compressive-strength tests to project the potential strength of concrete at later ages.  
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.  
1.5 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: 27-Jul-1999
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.61 - Testing for Strength

Relations

• Replaced By: ASTM C918-02 - Standard Test Method for Measuring Early-Age Compressive Strength and Projecting Later-Age Strength
• Effective Date: 10-Jul-2002

Standards Content (Sample)

e1
Designation: C 918 – 97
Standard Test Method for
Measuring Early-Age Compressive Strength and Projecting
1
Later-Age Strength
This standard is issued under the fixed designation C 918; 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.
1
e NOTE—Editorial corrections were made throughout the standard in August 1999.
1. Scope C 670 Practice for Preparing Precision and Bias Statements
4
for Test Methods for Construction Materials
1.1 This test method covers a procedure for making and
C 1074 Practice for Estimating Concrete Strength by the
curing concrete specimens and for testing them at an early age.
4
Maturity Method
The specimens are stored under standard-curing conditions and
C 1231 Practice for Use of Unbonded Caps in Determina-
the measured temperature history is used to compute a maturity
tion of Compressive Strength of Hardened Concrete Cyl-
index that is related to strength gain.
4
inders
1.2 This test method also covers a procedure for using the
results of early-age compressive-strength tests to project the
3. Terminology
potential strength of concrete at later ages.
3.1 Definitions:
1.3 The values stated in SI units are to be regarded as the
3.1.1 Refer to Practice C 1074 for the definitions of the
standard. The values given in parentheses are for information
following terms: datum temperature, equivalent age, maturity,
only.
maturity function, maturity index, and temperature–time factor.
1.4 The text of this standard references notes and footnotes
3.2 Definitions of Terms Specific to This Standard:
which provide explanatory material. These notes and footnotes
3.2.1 potential strength, n—the strength of a test specimen
(excluding those in tables and figures) shall not be considered
that would be obtained at a specified age under standard curing
as requirements of the standard.
conditions.
1.5 This standard does not purport to address all of the
3.2.2 prediction equation, n—the equation representing the
safety concerns, if any, associated with its use. It is the
straight-line relationship between compressive strength and the
responsibility of the user of this standard to establish appro-
logarithm of the maturity index.
priate safety and health practices and determine the applica-
3.2.2.1 Discussion—The prediction equation is used to
bility of regulatory limitations prior to use.
project the strength of a test specimen based upon its measured
2. Referenced Documents early-age strength. The general form of the prediction equation
used in this test method is:
2.1 ASTM Standards:
C 31/C 31M Practice for Making and Curing Concrete Test S 5 S 1 b log M 2 log m (1)
~ !
M m
2
Specimens in the Field
where:
C 39 Test Method for Compressive Strength of Cylindrical
S 5 projected strength at maturity index M,
3
M
Concrete Specimens
S 5 measured compressive strength at maturity index m,
m
C 192/C 192M Practice for Making and Curing Concrete
b 5 slope of the line,
4
Test Specimens in the Laboratory
M 5 maturity index under standard curing conditions, and
C 470 Specification for Molds for Forming Concrete Test
m 5 maturity index of the specimen tested at early age.
4
Cylinders Vertically
The prediction equation is developed by performing com-
C 617 Practice for Capping Cylindrical Concrete Speci-
4
pressive strength tests at various ages, computing the corre-
mens
sponding maturity indices at the test ages, and plotting the
compressive strength as a function of the logarithm of the
1
This test method is under the jurisdiction of ASTM Committee C-9 on Concrete
maturity index. A best-fit line is drawn through the data and the
and Concrete Aggregates and is the direct responsibility of Subcommittee C09.61 on
slope of this line is used in the prediction equation.
Testing for Strength.
3.2.3 projected strength, n—the potential strength estimated
Current edition approved Jan. 10, 1997. Published March 1997. Originally
published as C 918 – 80. Last previous edition C 918 – 93.
2
Annual Book of ASTM Standards, Vol 04.10.
3
Annual Book of ASTM Standards, Vol 04.07.
4
Annual Book of ASTM Standards, Vol 04.02.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
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C 918
by using the measured early-age strength and the previously 6.2 Molds shall conform to the requirements for cylinder
established prediction equation. molds in Specification C 470.
6.3 Temperature Recorder:
4. Summary of Test Method
6.3.1 A device is required to monitor and record the
temperature of a test specimen as a function of time. Accept-
4.1 Cylindrical test specimens are prepared and cured in
able devices include thermocouples or thermistors connected to
accordance with the appropriate sections of Practice C 31 or in
...