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Wb Designation: C 1018 - 97 AMERICAN SOCIETY FOR TESTING AND MATEAIALS100 Barr Harbw Dr West Conshohacken PA 19428Pepnnted from the Annual Baok of ASTM Standards Gwyqhi ASTM
Standard Test Method for
Flexural Toughness and First-Crack Strength of
Fiber-Reinforced Concrete (Using Beam With
Third-Point Loading)’

This standard IS issued under the fixed designation C 1018; the number immediarcly following Ihe designation mdicates the year of
ongmal adoption or. in the case of re~~aon. the year of last rewsion. A number m parenthew mdwates the year of last reapproval. A
superscnpt epsilon If) Indicates an editorial change since the last rwwon or reappro\zL

1. Scope
I I This test method evaluates the flexural performance of

toughness parameters derived from tiber-reinforced concrete
in terms of areas under the load-deflection curve obtained by
testing a simply supported beam under third-point loading.

NCJTE I-Toughness determined in terms of areas under the load-
deflection curve is an indication of the energy absorption capability of
the particular test specimen, and, consequently. its magnitude depends
directly on the geometrical charactenstics of the test specimen and the
loading system.

I.2 This test method provides for the determination of a
number of ratios called toughness indices that identify the
pattern of material behavior up to the selected deflection
criteria. These indices are determined by dividing the area
under the load - deflection curve up to a specified deflection
criterion. by the area up to the deflection at which first crack
is deemed to have occurred. Residual strength factors that
represent the average post-crack load retained over a specific
deflection interval as a percentage of the load at first crack
are derived from these indices.

NOTE 2-Index values may be increased by preferential alignment of
fibers parallel to the longitudinal axis of the beam caused by fiber
contact with the mold surfaces or by external vibration. However, index
values appear to be independent of geometrical specimen and testing
variables. such as span length. which do not directly affect tiber

I .3 This test method provides for the determination of the
first-crack flexural strength using the load corresponding to
the point on the load-deflection curve defined in 3.1.1 as first
crack, and the formula for modulus of rupture given in Test
Method C 78.

1.4 Values of flexural toughness and first-crack flexural
strength stated in inch-pound units are to be regarded as the
standard. Values of toughness indices and residual strength
factors are independent of the system of units used to
measure load and deflection.

1.5 This standard does not purport to address ail c?f the
.sqf&y concerns, if any. associated with its use. It is the
responsibility of’ the user (!I- this standard to establish appro-
priate safety and health practices and determine the upplica-
hility yl’reguiators limitations prior to use.

’ l’lus test method 1s under the jurisdiction of ASTM Committee C-9 on
Concrete and Concrete Awegates and is the direct responsibility of Subcommillee
C09.42 on Fiber-Remforced Concrete.

Currcnl edition approved Dee IO, 1997. Published October 1998. Originally
pubhshed as C IO1 8 - 84. Last previous edition C IO I X - 94h

2. Referenced Documents

2. I ASTM Standard.r.
C 31 Practice for Making and Curing Concrete Test

Specimens in the Field’
C 42 Test Method for Obtaining and Testing Drilled Cores

and Sawed Beams of Concrete’
C 78 Test Method for Flexural Strength of Concrete

(Using Simple Beam with Third-Point Loading)
C 172 Practice for Sampling Freshly Mixed Concrete2
C I92 Practice for Making and Curing Concrete Test

Specimens in the Laboratory2
C 670 Practice for Preparing Precision and Bias State-

ments for Test Methods for Construction Materials’
C 823 Practice for Examination and Sampling of Hard-

ened Concrete in Constructions’

3. Terminology
3. I Descriptions qf Terms Specific to This Standard:
3.1.1 first crack-the point on the load -deflection curve

at which the form of the curve first becomes nonlinear
(approximates the onset of cracking in the concrete matrix).

3.1.2 first-crack deflection-the deflection value on the
load-deflection curve at first crack.

3.1.3 ,first-crack strength-the stress obtained when the
load corresponding to first crack is inserted in the formula
for modulus of rupture given in Test Method C 78.

3.1.4 first-crack toughness-the energy equivalent to the
area under the load -deflection curve up to the first-crack

3. I .5 tozcghnuss-the energy equivalent to the area under
the load-deflection curve up to a specified deflection.

3.1.6 toughness indices-the numbers obtained by di-
viding the area up to a specified deflection by the area up to
first crack.


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