ASTM C191-21

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: C191 − 19 C191 − 21 American Association State
Highway and Transportation Officials Standard
AASHTO No.: T131
Standard Test Methods for
Time of Setting of Hydraulic Cement by Vicat Needle
This standard is issued under the fixed designation C191; 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 These test methods determine the time of setting of hydraulic cement by means of the Vicat needle. Two test methods are
given; Test Method A is the Reference Test Method using the manually operated standard Vicat apparatus, while Test Method B
permits the use of an automatic Vicat machine that has, in accordance with the qualification requirements of this method,
demonstrated acceptable performance.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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.
Warning: Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged
exposure.
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, health, and environmental 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.)
1.4 The text of this standard references these test methods reference 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.
NOTE 1—For the test method for determining the time of setting by Gillmore needles, see Test Method C266.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
C150/C150M Specification for Portland Cement
These test methods are under the jurisdiction of ASTM Committee C01 on Cement and is the direct responsibility of Subcommittee C01.30 on Time of Set.
Current edition approved Aug. 1, 2019Oct. 1, 2021. Published August 2019November 2021. Originally approved in 1944. Last previous edition approved in 20182019
as C191 – 18a.C191 – 19. DOI: 10.1520/C0191-19.10.1520/C0191-21.
Section on Safety, Manual of Cement Testing, Annual Book of ASTM Standards, Vol 04.01.
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
C191 − 21
C151/C151M Test Method for Autoclave Expansion of Hydraulic Cement
C183/C183M Practice for Sampling and the Amount of Testing of Hydraulic Cement
C187 Test Method for Amount of Water Required for Normal Consistency of Hydraulic Cement Paste
C219 Terminology Relating to Hydraulic and Other Inorganic Cements
C266 Test Method for Time of Setting of Hydraulic-Cement Paste by Gillmore Needles
C305 Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency
C511 Specification for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic
Cements and Concretes
C595/C595M Specification for Blended Hydraulic Cements
C1005 Specification for Reference Masses and Devices for Determining Mass and Volume for Use in Physical Testing of
Hydraulic Cements
C1157/C1157M Performance Specification for Hydraulic Cement
D1193 Specification for Reagent Water
3. Terminology
3.1 Definitions—The terms used in this test method are defined in accordance with Terminology C219.
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology C219.
4. Summary of Test Method
4.1 A paste that is proportioned and mixed to normal consistency, as described in the Test Method C187, is molded and placed
in a moist cabinet and allowed to start setting. Periodic penetration tests are performed on this paste by allowing a 1-mm 1 mm
Vicat needle to settle into this paste. The Vicat initial time of setting is the time elapsed between the initial contact of cement and
water and the time when the penetration is measured or calculated to be 25 mm. The Vicat final time of setting is the time elapsed
between initial contact of cement and water and the time when the needle does not leave a complete circular impression in the paste
surface.
5. Significance and Use
5.1 This test method provides a means of determining compliance with a specification limit for Vicat time of setting. Refer to the
appropriate specification for the cement to determine if this test method is used for specification compliance.
5.2 Time of setting measured by this method will not necessarily provide the same results as the time of setting of hydraulic
cement paste measured by other methods, or the time of setting of mortar or concrete.
6. Apparatus
6.1 Vicat Apparatus—See Annex A1.1 and Fig. A1.1. The Vicat apparatus for this test method shall have a movable rod, B, of mass
300 6 0.5 g.
6.1.1 The end of the rod used for measuring penetration shall have a straight steel removable needle with a diameter of 1.00 6
0.05 mm and length no less than 50 mm.
6.1.2 The needle end that contacts the specimen shall be flat, plane, and at right angles to the axis of the rod.
6.2 Reference Masses and Devices for Determining Mass, conforming to the requirements of Specification C1005. The devices
for determining mass shall be evaluated for continuing precise performance utilizing the procedure in Specification C1005,
Appendix X1 using a verification check mass of approximately 1000 g.
6.3 Glass Graduates, 200 or 250-mL 250 mL capacity, and conforming to the requirements of Specification C1005.
6.4 Plane non-adsorptive plate,Non-Adsorptive Plate, 100 6 5 mm square of similar planeness, corrosivity, and absorptivity to
that of glass (see Annex A1.1, Fig. A1.1, H).
C191 − 21
6.5 Flat trowel,Trowel, having a sharpened straight-edged steel blade 100 to 150 mm in length. The edges when placed on a plane
surface shall not depart from straightness by more than 1 mm.
6.6 Conical ring,Ring, made of a rigid, non-corroding, non-absorbent material and having a height of 40 6 1 mm, an inside
diameter at the bottom of 70 6 3 mm, and an inside diameter at the top of 60 6 3 mm (see Annex A1.1, Fig. A1.1, G).
6.7 Mixer, bowl,Bowl, and paddle,Paddle, conforming to Practice C305.
6.8 Automatic Vicat Needle Apparatus for Method B—The apparatus shall be equipped with a Vicat needle as described in 6.1.1
and 6.1.2. The total mass supported by the needle tip at the time of measurement shall be 300 6 0.5 g. The instrument shall be
capable of automatically completing and recording penetration measurements of a test specimen at predetermined time intervals
not exceeding 10 min and make each penetration test at least 5 mm away from any previous penetration and at least 10 mm away
from the inner side of the mold.
6.9 Specimen Mold for Method B—The cement paste is held in a conical ring with the height of 40 6 1 mm and a removable base
plate. The test surface shall have a minimum diameter of 60 6 3 mm.
6.10 Inspect and document Section 6 apparatus for conformance to the requirements of this test method at least every 2 ⁄2 years
years (see Note 2).
NOTE 2—Specification C1005 requires annual compliance checks for the reference masses and for the devices for determining mass.
7. Reagents and Materials
7.1 Mixing Water—Potable water is satisfactory for routine tests. Use water conforming to the requirements of Specification
D1193 for Type III or Type IV grade reagent water for all referee and cooperative tests.
8. Sampling
8.1 When the test is required for acceptance testing, sample cement in accordance with Practice C183/C183M.
9. Conditioning
9.1 Maintain the temperature and the humidity of the mixing room and the temperature of the mixing water in accordance with
Specification C511 (see section titled “Requirements for Cement Mixing Rooms”).
9.2 The moist cabinet or moist room shall be in accordance with Specification C511.
9.3 The dry materials shall be within the temperature range of the mixing room prior to testing.
10. Preparation of Cement Paste
NOTE 3—See Test Method C187.
10.1 The cement paste used for the determination of the time of setting is obtained from one of the following methods:
10.1.1 Prepare a new batch of paste by mixing 650 g of cement with the percentage of mixing water required for normal
consistency (Test Method C187), following the procedure described in Practice C305.
10.1.2 For method A, at the option of the tester, use the test specimen used for determining normal consistency (see Note 34).
10.1.3 At the option of the tester, use the paste remaining from the batch used for the autoclave specimen (Test Method
C151/C151M) or from the normal consistency determination (Test Method C187).
C191 − 21
NOTE 4—The specimen used for the determination of the normal consistency will have an irregular surface, making it unsuitable for method B.
11. Calculation
11.1 Calculate the Vicat time of setting to the nearest 1 min as follows:
~H 2 E!
3 C 2 25 1E (1)
~ !
SS D D
C 2D
~ !
where:
E = time in minutes of last penetration greater than 25 mm,
H = time in minutes of first penetration less than 25 mm,
C = penetration reading at time E, and
D = penetration reading at time H.
11.2 Calculate the Vicat final time of setting by determining the elapsed time between the time of the initial contact between
cement and water and the time when the Vicat final time of setting end-point described in 14.3 is determined, rounded to the nearest
5 min.
12. Report
12.1 Report the time of setting and the method used as follows:
Vicat time of setting (A or B) ______ min
Vicat final time of setting (A or B) ______ min
Method A—Manual Vicat Needle Apparatus
13. Manual Vicat Apparatus
13.1 Refer to the Apparatus section, paragraphs 6.1, 6.4, and 6.6, and Annex A1 for a description of the Vicat apparatus.
14. Procedure A
14.1 Molding Test Specimen—Quickly form the cement paste, prepared as described in the section on preparation of cement paste,
into a ball with gloved hands and toss six times from one hand to the other, maintaining the hands about 150 mm (6 in.) apart.
Press the ball, resting in the palm of the hand, into the larger end of the conical ring, G,Fig. A1.1, held in the other hand, completely
filling the ring with paste. Remove the excess at the larger end by a single movement of the palm of the hand. Place the ring on
its larger end onto the non-absorptive plate, H, and slice off the excess paste at the smaller end at the top of the ring by a single
oblique stroke of the trowel held at a slight angle with the top of the ring. Smooth the top of the specimen, if necessary, with one
or two light touches of the pointed end of the trowel. During the operation of cutting and smoothing, take care not to compress
the paste. Immediately after molding, place the test specimen in the moist cabinet or moist room and allow it to remain there except
when penetration measurements are being made. The specimen shall remain in the conical mold, supported by the non-absorptive
plate throughout the test period.
14.2 Time of Setting Determination—Allow the time of setting specimen to remain in the moist cabinet or moist room for 30 min
after molding without being disturbed. Determine the penetration of the 1-mm 1 mm needle at this time and every 15 min thereafter
(every 10 min for Type III cements) until a penetration of 25 mm or less is obtained. Perform the penetration test by lowering the
needle D of the rod B until it rests on the surface of the cement paste. Tighten the setscrew, E, and set the indicator, F, at the upper
end of the scale, or take an initial reading. Release the rod quickly by releasing the set screw, E, and allow the needle to settle for
30 s; then take the reading to determine the penetration. At the option of the tester, if the paste is obviously quite soft on the early
readings, retard the fall of the rod to avoid bending the 1-mm 1 mm needle, but when actual penetration measurements to determine
the time of setting are made, release the rod only by the setscrew. Make each penetration test at least 5 mm away from any previous
penetration and at least 10 mm away from the inner side of the mold. Record the results of all penetration tests and, by
interpolation, determine the time when a penetration of 25 mm is obtained. The elapsed time between the initial contact of cement
and water and the penetration of 25 mm is the Vicat time of setting or Vicat initial time of setting.
C191 − 21
14.3 Determine the Vicat final time of setting end point to be the first penetration measurement that does not mark the specimen
surface with a complete circular impression. Verify final set by performing two additional penetration measurements on different
areas of the specimen surface. Obtain verification measurements within 90 s of the first “final set” measurement. The elapsed time
between the initial contact of cement and water and the end point determination above is the Vicat final time of setting.
14.4 Precautions—Keep all the apparatus free from vibration during the penetration test. Keep the 1-mm 1 mm needle straight
and clean. The needle must be kept clean to prevent cement from adhering to the sides of the needle and decreasing penetration,
and to prevent cement from adhering to the point and increasing penetration.
15. Precision and Bias
15.1 Precision:
15.1.1 The single-operator (within-laboratory) standard deviation has been found to be 12 min for the initial time of setting,
throughout the range of 49 to 202 min, and 20 min for the final time of settings throughout the range of 185 to 312 min. Therefore,
results of two properly conducted tests by the same operator on Vicat initial time of setting of similar paste should not differ from
each other by more than 34 min and on Vicat final time of setting of similar pastes should not differ from each other by more than
56 min.
15.1.2 The multilaboratory (between-laboratory) standard deviation has been found to be 16 min for the initial time of setting
throughout the range of 49 to 207 min, and 43 min for the final time of setting throughout the range of 185 to 312 min. Therefore,
results of two properly conducted tests from two different laboratories on Vicat initial time of setting of similar pastes should not
differ from each other by more than 45 min, and on Vicat final time of setting of similar pastes should not differ from each other
by more than 122 min.
15.2 Bias—Since there are no accepted reference materials suitable for determining the bias for the procedure in this test method,
no statement on bias is presented.
Method B—Automatic Vicat
16. Automatic Vicat Apparatus
16.1 Automatic Vicat Needle Apparatus—Refer to the Apparatus section, paragraphs 6.8 and 6.9, for a description of the Automatic
Vicat needle apparatus.
17. Procedure
17.1
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