ASTM C918/C918M-13

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

SIGNIFICANCE AND USE
5.1 This test method provides a procedure to estimate the potential strength of a particular test specimen based upon its measured strength at an age as early as 24 h.4 The early-age test results provide information on the variability of the concrete production process for use in process control.  
5.2 The relationship between early-age strength of test specimens and strength achieved at some later age under standard curing depends upon the materials comprising the concrete. In this test method, it is assumed that there is a linear relationship between strength and the logarithm of the maturity index. Experience has shown that this is an acceptable approximation for test ages between 24 h and 28 days under standard curing conditions. The user of this test method shall verify that the test data used to develop the prediction equation are represented correctly by the linear relationship. If the underlying relationship between strength and the logarithm of the maturity index cannot be approximated by a straight line, the principle of this test method is applicable provided an appropriate equation is used to represent the non-linear relationship.  
5.3 Strength projections are limited to concretes using the same materials and proportions as the concrete used to establish the prediction equation.Note 1—Confidence intervals developed in accordance with 10.2 are helpful in evaluating projected strengths.  
5.4 This test method is not intended for estimating the in-place strength of concrete. Practice C1074 provides procedures for using the measured in-place maturity index to estimate in-place strength.
SCOPE
1.1 This test method covers a procedure for making and curing concrete specimens and for testing them at an early age. The specimens are stored under standard or accelerated 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 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 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. (Warning—Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure.)2

General Information

• Status: Historical
• Publication Date: 30-Nov-2013
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.61 - Testing for Strength

Relations

• Replaces: ASTM C918/C918M-07 - Standard Test Method for Measuring Early-Age Compressive Strength and Projecting Later-Age Strength
• Effective Date: 01-Dec-2013
• Replaced By: ASTM C918/C918M-20 - Standard Test Method for Measuring Early-Age Compressive Strength and Projecting Later-Age Strength
• Effective Date: 01-Apr-2020
• Referred By: ASTM C1074-19e1 - Standard Practice for Estimating Concrete Strength by the Maturity Method
• Effective Date: 01-Dec-2013
• Referred By: ASTM C1768/C1768M-12(2017) - Standard Practice for Accelerated Curing of Concrete Cylinders
• Effective Date: 01-Dec-2013

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: C918/C918M − 13
Standard Test Method for
Measuring Early-Age Compressive Strength and Projecting
1
Later-Age Strength
This standard is issued under the fixed designation C918/C918M; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope* C31/C31M Practice for Making and Curing Concrete Test
Specimens in the Field
1.1 This test method covers a procedure for making and
C39/C39M Test Method for Compressive Strength of Cylin-
curing concrete specimens and for testing them at an early age.
drical Concrete Specimens
The specimens are stored under standard or accelerated curing
C192/C192M Practice for Making and Curing Concrete Test
conditions and the measured temperature history is used to
Specimens in the Laboratory
compute a maturity index that is related to strength gain.
C470/C470M Specification for Molds for Forming Concrete
1.2 This test method also covers a procedure for using the
Test Cylinders Vertically
results of early-age compressive-strength tests to project the
C617/C617M Practice for Capping Cylindrical Concrete
potential strength of concrete at later ages.
Specimens
1.3 The values stated in either SI units or inch-pound units C670 Practice for Preparing Precision and Bias Statements
for Test Methods for Construction Materials
are to be regarded separately as standard. The values stated in
each system may not be exact equivalents; therefore, each C1074 Practice for Estimating Concrete Strength by the
Maturity Method
system shall be used independently of the other. Combining
values from the two systems may result in non-conformance C1231/C1231M Practice for Use of Unbonded Caps in
DeterminationofCompressiveStrengthofHardenedCon-
with the standard.
crete Cylinders
1.4 The text of this standard references notes and footnotes
C1768/C1768M Practice forAccelerated Curing of Concrete
which provide explanatory material. These notes and footnotes
Cylinders
(excluding those in tables and figures) shall not be considered
as requirements of the standard.
3. Terminology
1.5 This standard does not purport to address all of the
3.1 Definitions:
safety concerns, if any, associated with its use. It is the
3.1.1 Refer to Practice C1074 for the definitions of the
responsibility of the user of this standard to establish appro-
following terms: datum temperature, equivalent age, maturity,
priate safety and health practices and determine the applica-
maturityfunction,maturityindex,andtemperature–timefactor.
bility of regulatory limitations prior to use. (Warning—Fresh
3.2 Definitions of Terms Specific to This Standard:
hydraulic cementitious mixtures are caustic and may cause
2
3.2.1 potential strength, n—the strength of a test specimen
chemical burns to skin and tissue upon prolonged exposure.)
that would be obtained at a specified age under standard curing
conditions.
2. Referenced Documents
3 3.2.2 prediction equation, n—the equation representing the
2.1 ASTM Standards:
straight-line relationship between compressive strength and the
logarithm of the maturity index.
3.2.2.1 Discussion—The prediction equation is used to proj-
1
This test method is under the jurisdiction of ASTM Committee C09 on
ect the strength of a test specimen based upon its measured
Concrete and Concrete Aggregatesand is the direct responsibility of Subcommittee
early-age strength. The general form of the prediction equation
C09.61 on Testing for Strength.
Current edition approved Dec. 1, 2013. Published January 2014. Originally used in this test method is:
approved in 1980. Last previous edition approved in 2007 as C918 – 07. DOI:
S 5 S 1b log M 2 log m (1)
~ !
M m
10.1520/C0918_C0918M-13.
2
Section on Safety Precautions, Manual of Aggregate and Concrete Testing,
where:
Annual Book of ASTM Standards, Vol. 04.0.2.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
S = projected strength at maturity index M,
M
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
S = measured compressive strength at maturity index m,
m
Standards volume information, refer to the standard’s Document Summary page on
b = slope of the line,
the ASTM website.
*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 ----------------------
C918/C918M − 13
helpful in evaluating projected strengths.
M = maturity index under standard curing conditions, and
m = maturity index of the specimen tested at early age.
5.4 This test method is not intended for estima
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C918/C918M − 07 C918/C918M − 13
Standard Test Method for
Measuring Early-Age Compressive Strength and Projecting
1
Later-Age Strength
This standard is issued under the fixed designation C918/C918M; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers a procedure for making and curing concrete specimens and for testing them at an early age. The
specimens are stored under standard-curing standard or accelerated 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 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 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. (Warning—Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and
2
tissue upon prolonged exposure.)
2. Referenced Documents
3
2.1 ASTM Standards:
C31/C31M Practice for Making and Curing Concrete Test Specimens in the Field
C39/C39M Test Method for Compressive Strength of Cylindrical Concrete Specimens
C192/C192M Practice for Making and Curing Concrete Test Specimens in the Laboratory
C470/C470M Specification for Molds for Forming Concrete Test Cylinders Vertically
C617C617/C617M Practice for Capping Cylindrical Concrete Specimens
C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
C1074 Practice for Estimating Concrete Strength by the Maturity Method
C1231/C1231M Practice for Use of Unbonded Caps in Determination of Compressive Strength of Hardened Concrete Cylinders
C1768/C1768M Practice for Accelerated Curing of Concrete Cylinders
3. Terminology
3.1 Definitions:
3.1.1 Refer to Practice C1074 for the definitions of the following terms: datum temperature, equivalent age, maturity, maturity
function, maturity index, and temperature–time factor.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 potential strength, n—the strength of a test specimen that would be obtained at a specified age under standard curing
conditions.
1
This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregatesand is the direct responsibility of Subcommittee C09.61 on
Testing for Strength.
Current edition approved July 15, 2007Dec. 1, 2013. Published August 2007January 2014. Originally approved in 1980. Last previous edition approved in 20022007 as
C918 – 02.C918 – 07. DOI: 10.1520/C0918_C0918M-07.10.1520/C0918_C0918M-13.
2
Section on Safety Precautions, Manual of Aggregate and Concrete Testing, Annual Book of ASTM Standards, Vol. 04.0.2.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*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 ----------------------
C918/C918M − 13
3.2.2 prediction equation, n—the equation representing the straight-line relationship between compressive strength and the
logarithm of the maturity index.
3.2.2.1 Discussion—
The prediction equation is used to project the strength of a test specimen based upon its measured early-age strength. The general
form of the prediction equation used in this test m
...