ASTM C341 - C 341M - 18

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Designation: C341/C341M −18
Standard Practice for
Preparation and Conditioning of Cast, Drilled, or Sawed
Specimens of Hydraulic-Cement Mortar and Concrete Used
for Length Change Measurements
1
This standard is issued under the ﬁxed designation C341/C341M; 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 practice covers the procedures for the preparation
and conditioning of cast, drilled, or sawed specimens of
hydraulic-cement mortar and concrete for length change due to
causes other than externally applied forces. It can be readily
adapted, if desired, to studies of length change involving
alternative schedules or environmental treatments.
1.2 The values stated in either inch-pound units or SI units
shall be regarded separately as standard. The units stated in
each system may not be exact equivalents; therefore, each
system must be used independently of the other, without
combining in any way. The inch-pound units are shown in
brackets.
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 appro-
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
2
A276/A276M Speciﬁcation for Stainless Steel Bars and
Shapes
C125 Terminology Relating to Concrete and Concrete Ag-
gregates
C31/C31M Practice for Making and Curing Concrete Test
Specimens in the Field
C42/C42M Test Method for Obtaining and Testing Drilled
Cores and Sawed Beams of Concrete
C157/C157M Test Method for Length Change of Hardened
Hydraulic-Cement Mortar and Concrete
C192/C192M Practice for Making and Curing Concrete Test
Specimens in the Laboratory
C490/C490M Practice for Use of Apparatus for the Deter-
mination of Length Change of Hardened Cement Paste,
Mortar, and Concrete
C666/C666M Test Method for Resistance of Concrete to
Rapid Freezing and Thawing
3. Terminology
3.1 Deﬁnitions:
3.1.1 For deﬁnitions of terms used in this practice, refer to
Terminology C125.
3.2 Deﬁnitions of Terms Speciﬁc to This Standard:
3.2.1 length change, n—an increase or decrease in a linear
dimension of a test specimen, which has been caused to change
by any factor other than externally applied forces and tempera-
ture changes.
4. Signiﬁcance and Use
4.1 Measurements of length change permit assessment of
the potential for volumetric expansion or contraction of cast,
drilled, or sawed specimens of hydraulic-cement mortar, and
concrete due to various causes other than externally applied
forces and temperature changes. This practice is particularly
useful for comparative evaluation of this potential in different
mortar or concrete specimens.
5. Apparatus
5.1 Length Comparator—The length comparator shall gen-
erally conform to the requirements of Speciﬁcation C490/
C490M, except that it shall be constructed to accommodate the
specimens to be tested under this practice, which shall have
gauge lengths of 75 mm [3 in.] or more.
5.1.1 Gauge Studs in Ends of Specimens—When the com-
parator is to be used to measure between gauge studs in the
1
This practice is under the jurisdiction of ASTM Committee C09 on Concrete
and Concrete Aggregates and is the direct responsibility of Subcommittee C09.68 on
Volume Change.
Current edition approved Dec. 1, 2018. Published January 2019. Originally
approved in 1954. Last previous edition approved in 2013 as C341/C341M – 13.
DOI: 10.1520/C0341_C0341M-18.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. 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
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
1
 

ends of specimens, the gauge length for computing percentage
length change shall be considered to be the distance between
the innermost ends of the gauge studs, and the contact
terminals of the comparator shall be plane, polished, heat-
treated surfaces as described in Speciﬁcation C490/C490M.
Fig. 3 of Speciﬁcation C490/C490M shows one type of
comparator that has been found suitable for such specimens. A
horizontal comparator is desirable for specimens that are
considered too large to be handled by the type of comparator
illustrated in Fig. 3 of Speciﬁcation C490/C490M.
5.1.2 Gauge Studs on Sides of Specimen—When the com-
parator is to be used to measure between gauge studs on the
sides of specimens, the contact terminals shall be conical,
heat-treated surfaces as shown in Fig. 1, which illustrates a
type of comparator that has been found satisfactory for this
type of specimen. In this case, the gauge length shall be the
distance between the reference points located in the exposed
ends of the gauge studs (see 5.2).
5.2 Gauge Studs—Gauge studs shall be Type 316 stainless
steel, meeting Speciﬁcation A276/A276M.
5.2.1 For Ends of Specimens—Gauge studs that are to be
located in the ends of specimens shall have a rounded surface
to provide point contact with the terminals of the comparator.
The types of studs described in Speciﬁcation C490/C490M are
suitable for insertion in drilled holes. Spherical studs having a
diameter of 6 to 10 mm [
1
⁄
4
to
3
⁄
8
in.], or studs that are sections
of spheres of similar diameter, are suitable for cementing to the
ends of specimens.
5.2.2 For Sides of Specimens—The exposed end of gauge
studs that are to be located on the sides of specimens shall have
a plane surface with a diameter or diagonal of 10 to 13 mm [
3
⁄
8
to
1
⁄
2
in.]. For dry setting, the length of the stud shall be 13 to
16 mm [
1
⁄
2
to
5
⁄
8
in.]. Shorter lengths of stud, including plane
disks, shall be satisfactory for studs that are to be cemented.
5.3 Drying Room and Controls—A drying room and con-
trols as described in Test Method C157/C157M shall be used
for storing specimens in air.
6. Sampling
6.1 Samples of drilled or sawed hydraulic cement mortar or
concrete shall be obtained in accordance with the section on
Sampling of Test Method C42/C42M.
6.2 Samples of ﬁeld cast hydraulic cement mortar or con-
crete shall be cast in accordance with Practice C31/C31M.
6.3 Constituent materials for concrete or mortar specimens
made in the laboratory for use in this practice shall be sampled
using applicable standard methods.
6.3.1 The specimens for use in this practice prepared from
the constituent materials in the laboratory shall be cast prisms
or cylinders made and cured in accordance with the applicable
requirements of Practice C192/C192M and Practice C490/
C490M.
7. Test Specimens
7.1 Test specimen geometry shall be either cylindrical or
rectangular prisms. Specimens shall be either cast from freshly
mixed materials or drilled or sawn from existing concrete or
mortar structures. Specimens shall be free from reinforcing
steel, visible cracks, or other structural defects. They shall be of
any size but specimens that are to be compared shall not differ
in their cross-sectional dimensions by more than 10 % or in
length by more than 20 % (Note 1). The gauge length shall be
at least six times the maximum nominal size of the coarse
aggregate but not less than 75 mm [3 in.], and that the
minimum cross-sectional dimension be at least three times the
maximum nominal size of the coarse aggregate but not less
than 50 mm [2 in.]. When the gauge studs are to be located on
FIG. 1 Type of Suitable Extensometer for Measurement of Length Change of Specimens Having Gauge Studs on Sides
C341/C341M − 18
2
 

the sides of the specimen, the over-all length of the specimen
shall exceed the gauge length by at least 50 mm [2 in.].
NOTE 1—Specimens used for length change measurements during
freeze thaw resistance testing as described in Test Method C666/C666M
should follow the dimensional requirements of that method.
8. Setting Gauge Studs
8.1 Gauge studs shall either be cast in place, dry-set or
cemented in drilled holes, or cemented directly to the surface
of the specimen.
8.2 Drilling Holes—For gauge studs that are to be
cemented, holes shall be drilled (Note 2) only slightly larger
than the studs. For gauge studs that are to be dry-set, holes shall
be drilled about 0.1 mm [0.005 in.] smaller in diameter than the
studs. In the case of small specimens, take care that the
specimens are not damaged by the drilling operation. The
location and depth of holes shall be as given in 8.2.1 and 8.2.2.
NOTE 2—Carbide-tipped masonry drills have been found most suitable
for this purpose.
8.2.1 For Gauge Studs in Ends of Specimen—Drill holes in
the ends of a specimen so that their longitudinal axes coincide
with the longitudinal axis of the specimen. The depth of the
holes shall be such that the gauge studs will project from 3 to
5mm[
1
⁄
8
in. to
3
⁄
16
in.] beyond the ends of the specimen.
8.2.2 For Gauge Studs in Sides of Specimen—Drill a pair of
holes in each of two opposite sides of the specimen to
compensate for warping and to provide a better average for
length change. Position both pairs of holes in a plane contain-
ing the longitudinal axis of the specimen and space to conform
to the length of the comparator. The center of each hole shall
be at least 25 mm [1 in.] from the end of the specimen. The
depth of the holes shall preferably be such that the top surfaces
of the gauge studs can be set about 3 mm [0.1 in.] below the
surface of the specimen.
8.3 Cementing Methods:
8.3.1 Studs Set in Holes—Position gauge studs in holes at
the depth speciﬁed in 8.2.1 or 8.2.2, as appropriate, with the
exposed end parallel to the surface of the specimen in the case
of studs having plane end surfaces. The cementing material
shall be stable and effective in either a wet or dry environment
and at temperatures up to 120 °C [250 °F]. The following
cementing materials have been found satisfactory:
8.3.1.1 Epoxy Resin—Epoxy resins for this purpose shall
cure at room temperatures and not soften upon exposure to
water immersion. Holes shall be free of loose particles and
visually dry to ensure good bond.
8.3.1.2 Portland-Cement Paste—Use a thick paste of Type
III Portland cement. Moisten each hole with about 5 mL of
water, cement the studs in place after the water has been
absorbed, and moist-cure the paste for approximately 24 h.
8.3.1.3 Other Cementing Media—Sulfur and Rose metal
have also proven satisfactory.
8.3.2 Studs Cemented to Surface—An epoxy resin system
that cures at room temperature and does not soften at a
temperature of 120 °C [250 °F] or soften upon exposure to
water immersion is the most satisfactory material for cement-
ing studs to the surface of a specimen. To ensure good bond, it
is essential that the surface be clean. Acid etching followed by
ﬂushing with water and drying is a satisfactory preparation of
the surface for bonding. The locations of the studs on the
specimen are the same as those prescribed for drilled holes in
8.2.1 and 8.2.2. The exposed end surface of each stud having
a plane end surface shall be parallel to the surface of the
specimen.
8.4 Dry-Setting Method—Drive the gauge studs to the depth
speciﬁed in 8.2.1 or 8.2.2, as appropriate, into holes that are
approximately 0.1 mm [0.005 in.] smaller in diameter than the
gauge studs, being careful not to deform the exposed ends of
the gauge studs during the driving operation.
8.5 Reference Points on Gauge Studs—On each gauge stud
located on the side of a specimen, establish a reference point by
drilling a hole approximately 1 mm in diameter (see Note 3)in
the end of the stud to a depth sufficient to provide clearance
between the bottom of the hole and the point of the comparator,
as shown in Fig. 1. A template (Fig. 1) will aid in spacing the
holes at proper gauge length, which shall be as nearly equal to
the mean gauge length of the comparator as practicable.
Remove burred edges from the reference point holes.
NOTE 3—A No. 56 American Standard Twist Drill or other bit suitable
to drill a hole approximately 1 mm or 0.046 in. in diameter is suitable for
this purpose.
9. Determination of Gauge Length of Specimens
9.1 Determine the gauge length of each specimen to an
accuracy of 1 %. In the case of specimens having gauge studs
on the sides, determine the gauge length by direct measurement
between the reference points with a suitable scale. Determine
the gauge length of specimens having gauge studs in the ends
by ﬁrst measuring the distance between the ends of the gauge
studs with suitable calipers and subtracting the lengths of the
two gauge studs.
10. Conditioning of Specimens for Measurement of Base
Length
10.1 Prior to the initial measurement for length, condition
specimens by immersion in lime-saturated water.
10.2 Maintain the temperature of the conditioning water at
23 62 °C [73.5 63.5 °F], except that during the last1hof
immersion immediately before making any measurement for
length maintain the temperature at 23.0 60.5 °C [73.4 61.0
°F] (Note 4). When measuring for length, remove the speci-
mens from water one at a time, wipe with a damp cloth, and
immediately measure for length using the comparator speciﬁed
in 5.1. Make length measurements at 7-day intervals and
continue conditioning until the change in length over a 7-day
period is less than 0.001 %. Use the length measurement that
determines that this criterion is met as the basis for calculating
length change occurring during the air or water storage period.
NOTE 4—Specimens used for length change measurements during
freeze thaw resistance testing as described in Test Method C666/C666M
should follow the conditioning of that method.
C341/C341M − 18
3
 

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摘要：

ASTM C341 - C 341M - 18 是ASTM国际标准组织发布的关于水泥混凝土和砂浆在硬化过程中长度与体积变化的标准化测试方法。该标准规范详细规定了如何通过测量试件的线性变化来评估材料在干燥、收缩、膨胀等条件下的体积稳定性，适用于实验室与现场质量控制。文档涵盖了试件制备、养护条件、测量设备校准及数据处理流程，特别强调在恒定温度与湿度环境下的重复性要求。该标准不仅适用于普通混凝土，也适用于轻骨料混凝土、自密实混凝土等特殊类别，为工程结构耐久性评估及材料配方优化提供了重要依据。内容同时以

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