EN ISO 17892-12:2018

SLOVENSKI STANDARD
01-november-2018
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SIST-TS CEN ISO/TS 17892-12:2004
SIST-TS CEN ISO/TS 17892-12:2004/AC:2010
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Geotechnical investigation and testing - Laboratory testing of soil - Part 12:
Determination of liquid and plastic limits (ISO 17892-12:2018)
Geotechnische Erkundung und Untersuchung - Laborversuche an Bodenproben - Teil
12: Bestimmung der Zustandsgrenzen (ISO 17892-12:2018)
Reconnaissance et essais géotechniques - Essais de laboratoire sur les sols - Partie 12:
Détermination des limites de liquidité et de plasticité (ISO 17892-12:2018)
Ta slovenski standard je istoveten z: EN ISO 17892-12:2018
ICS:
13.080.20 Fizikalne lastnosti tal Physical properties of soils
93.020 Zemeljska dela. Izkopavanja. Earthworks. Excavations.
Gradnja temeljev. Dela pod Foundation construction.
zemljo Underground works
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 17892-12
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2018
EUROPÄISCHE NORM
ICS 13.080.20; 93.020 Supersedes CEN ISO/TS 17892-12:2004
English Version
Geotechnical investigation and testing - Laboratory testing
of soil - Part 12: Determination of liquid and plastic limits
(ISO 17892-12:2018)
Reconnaissance et essais géotechniques - Essais de Geotechnische Erkundung und Untersuchung -
laboratoire sur les sols - Partie 12: Détermination des Laborversuche an Bodenproben - Teil 12: Bestimmung
limites de liquidité et de plasticité (ISO 17892- der Zustandsgrenzen (ISO 17892-12:2018)
12:2018)
This European Standard was approved by CEN on 15 June 2018.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 17892-12:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 17892-12:2018) has been prepared by Technical Committee ISO/TC 182
"Geotechnics" in collaboration with Technical Committee CEN/TC 341 “Geotechnical Investigation and
Testing” the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2019, and conflicting national standards shall
be withdrawn at the latest by January 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes CEN ISO/TS 17892-12:2004.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 17892-12:2018 has been approved by CEN as EN ISO 17892-12:2018 without any
modification.
INTERNATIONAL ISO
STANDARD 17892-12
First edition
2018-06
Geotechnical investigation and
testing — Laboratory testing of soil —
Part 12:
Determination of liquid and plastic
limits
Reconnaissance et essais géotechniques — Essais de laboratoire sur
les sols —
Partie 12: Détermination des limites de liquidité et de plasticité
Reference number
ISO 17892-12:2018(E)
©
ISO 2018
ISO 17892-12:2018(E)
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

ISO 17892-12:2018(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Apparatus . 2
4.1 General . 2
4.2 Fall cone method . 3
4.3 Casagrande method . 5
4.4 Plastic limit equipment . 6
5 Test procedure . 7
5.1 Choice of liquid limit method . 7
5.2 Specimen preparation . 7
5.3 Determination of liquid limit by the fall cone method . 8
5.4 Determination of liquid limit by the Casagrande method .10
5.5 Determination of plastic limit .12
6 Test results .13
6.1 Proportion of sample smaller than 0,4 mm .13
6.2 Liquid limit by the fall cone method .13
6.3 Liquid limit by the Casagrande method .15
6.4 Plastic limit .15
6.5 Plasticity index .16
7 Test report .16
7.1 Mandatory reporting .16
7.2 Optional reporting .16
Annex A (normative) Calibration, maintenance and checks .18
Annex B (normative) Additional parameters .25
Bibliography .27
ISO 17892-12:2018(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by the European Committee for Standardization (CEN) Technical
Committee CEN/TC 341 Geotechnical investigation and testing, in collaboration with ISO Technical
Committee TC 182, Geotechnics, in accordance with the Agreement on technical cooperation between
ISO and CEN (Vienna Agreement).
This first edition of ISO 17892-12 cancels and replaces ISO/TS 17892-12:2004, which has been
technically revised. It also incorporates ISO/TS 17892-12:2004/Cor.1:2006.
A list of all the parts in the ISO 17892 series can be found on the ISO website.
iv © ISO 2018 – All rights reserved

ISO 17892-12:2018(E)
Introduction
This document covers areas in the international field of geotechnical engineering never previously
standardised internationally. It is intended that this document presents broad good practice and
significant differences with national documents is not anticipated. It is based on international practice
(see Reference [1]).
INTERNATIONAL STANDARD ISO 17892-12:2018(E)
Geotechnical investigation and testing — Laboratory
testing of soil —
Part 12:
Determination of liquid and plastic limits
1 Scope
This document specifies methods for the determination of the liquid and plastic limits of a soil. These
comprise two of the Atterberg limits for soils.
The liquid limit is the water content at which a soil changes from the liquid to the plastic state.
This document describes the determination of the liquid limit of a specimen of natural soil, or of
a specimen of soil from which material larger than about 0,4 mm has been removed. This document
describes two methods: the fall cone method and the Casagrande method.
NOTE The fall cone method in this document should not be confused with that of ISO 17892-6.
The plastic limit of a soil is the water content at which a soil ceases to be plastic when dried further.
The determination of the plastic limit is normally made in conjunction with the determination of the
liquid limit. It is recognized that the results of the test are subject to the judgement of the operator, and
that some variability in results will occur.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3310-1, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
ISO 14688-1, Geotechnical investigation and testing — Identification and classification of soil — Part 1:
Identification and description
ISO 17892-1, Geotechnical investigation and testing — Laboratory testing of soil — Part 1: Determination
of water content
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain
terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp
3.1
liquid limit
w
L
water content at which a soil passes from the liquid to the plastic state, as determined by the liquid
limit test
ISO 17892-12:2018(E)
3.2
plastic limit
w
P
water content at which a specimen ceases to be plastic when dried further, as determined by the plastic
limit test
3.3
plasticity index
I
P
numerical difference between the liquid limit and the plastic limit of a soil
3.4
non plastic soil
soil which has a plasticity index of zero or one for which the plastic limit cannot be determined
4 Apparatus
4.1 General
See also Annex A for more manufacturing tolerances (where appropriate), calibration, maintenance and
checks on the equipment.
4.1.1 Balance.
The balance shall have an accuracy of 0,01 g or 0,1 % of the weighed mass whichever value is the greater.
4.1.2 Test specimen containers.
Test specimen containers shall be made of a material that does not change mass as a result of repeated
drying cycles. Glass, porcelain and corrosion-resistant metals have been found to be suitable. Containers
shall have a capacity large enough to hold the mass of sample to be dried without spillage, but should
not be so large that the mass of the empty container is significantly in excess of that of the specimen.
Containers used for plastic limit determinations shall have close fitting lids.
4.1.3 Water.
Water should be distilled, de-ionized or demineralized. Where distilled is referred to in this document,
the terms are interchangeable.
4.1.4 Ancillary apparatus.
4.1.4.1 Spatulas.
4.1.4.2 Spray bottle (preferably of plastic).
4.1.4.3 Evaporating dishes.
4.1.4.4 Sieves complying with ISO 3310-1.
4.1.4.5 Flat mixing plate, for example glass.
4.1.4.6 Metal straightedge about 100 mm long.
2 © ISO 2018 – All rights reserved

ISO 17892-12:2018(E)
4.2 Fall cone method
4.2.1 Fall cone apparatus.
4.2.1.1 The fall cone apparatus is shown schematically in Figure 1. It shall permit the cone to be
held firmly initially and to be released instantaneously to fall freely in a vertical direction into the soil
specimen.
Key
1 vertical adjustment mechanism
2 penetration measurement device
3 fall cone
4 lock/release button
5 specimen cup
Figure 1 — Schematic of a fall cone apparatus
4.2.1.2 The fall cone apparatus shall have a vertical adjustment mechanism which allows the cone to
be raised or lowered and adjusted so that the tip of the cone just touches the surface of the specimen
before the cone is released.
4.2.1.3 The fall cone apparatus shall be equipped with a method of measuring the penetration of the
cone into the specimen after release to a resolution of 0,1 mm (or better), within the range 5 mm to
20 mm if the 60 g/60° cone is used, or within the range 10 mm to 30 mm if the 80 g/30° cone is used.
ISO 17892-12:2018(E)
4.2.2 Cones.
4.2.2.1 A typical cone is shown schematically in Figure 2.
Key
1 cone
2 shaft
3 cone tip
a deviation from the geometrical tip at manufacturing
b maximum tip wear
h height of the conical tip
β tip angle
Figure 2 — Example of liquid limit fall cone penetrometer (60° cone)
4.2.2.2 Either a 60 g/60° cone or a 80 g/30° cone complying with the requirements of Table 1 may be
used as it has been shown that both cones give essentially the same value for the liquid limit. Other cone
devices may be adopted provided they can be shown to give comparable results to those obtained from
the tests described herein.
Table 1 — Set of fall cones — Typical manufacturing specifications for masses and dimensions
Mass of cone plus shaft g 60 ± 0,06 80 ± 0,08
Tip angle β ° 60 ± 0,2 30 ± 0,2
Height of the cone tip h mm ≥20 ≥30
The deviation a from the geometrical tip at manufacturing mm <0,1 <0,1
4.2.2.3 The cone shall be manufactured of or coated with a corrosion resistant material such as
stainless steel or chromium, and should have smooth polished surfaces with an average roughness Ra of
less than 0,8 μm as a manufacturing specification. The cone surface has to remain smooth with use, and
should be replaced if the smooth surface is noticeably damaged.
4.2.2.4 The maximum wear b shall be less than 0,3 mm (see Figure 2).
4.2.3 Sample cup.
The sample cup shall be made of non-corrodible and rigid material, spherical or cylindrical in shape. If
cylindrical, it shall have a base parallel to the rim with a diameter of at least 50 mm and a depth of at
least 25 mm if the 60 g/60° cone is used and a depth of at least 40 mm if the 80 g/30° cone is used.
4 © ISO 2018 – All rights reserved

ISO 17892-12:2018(E)
4.2.4 Timing device.
A clock or stop-watch, or similar, capable of being read to the nearest 1 s.
4.3 Casagrande method
4.3.1 Casagrande apparatus.
The Casagrande apparatus is shown schematically in Figure 3. The apparatus consists of a specimen cup
which is raised by a cam and then dropped a specified distance onto a base. The device may be operated
by either a hand crank or electric motor. Dimensions, manufacturing specifications and tolerances are
included in Annex A. A Casagrande apparatus and grooving tool in accordance with other specifications
may be adopted provided it can be shown to give comparable results.
Key
1 specimen cup (= bowl)
2 hanger
3 carriage with pin
4 cam (turned by handle or motor)
5 base
6 rubber feet
7 point of contact
Figure 3 — Schematic of the Casagrande apparatus
4.3.2 Base and rubber feet.
The base and feet shall be made of rubber complying with the requirements of Table 2. The feet
supporting the base, are designed to provide isolation of the base from the work surface.
Table 2 — Base and feet — Rubber requirements
Hardness of the feet Hardness of the base Resilience of the base
Shore A value Resilience (rebound value)
Shore D value of at least 80
between 62 and 65 between S = 0,80 and S = 0,90
ISO 17892-12:2018(E)
Measurement of hardness (Shore A and Shore D) and resilience S is defined in A.3.7.5.
4.3.3 Specimen Cup.
The specimen cup should be made of brass or stainless steel. The shape of the cup shall be a segment of
a sphere. Dimensions, manufacturing specifications and tolerances are included in Annex A.
The cup should not be polished. The surface has to remain smooth with use, and should be replaced if
the smooth surface is noticeably damaged.
4.3.4 Cam.
The cam shall raise the cup smoothly and continuously to its maximum height, by increasing the radius
of the cam over at least 180° of cam rotation. The final portion of the cam shall be shaped so that the cup
does not develop an upward or downward velocity when the cam follower leaves the cam. A logarithmic
spiral design has been found to be satisfactory.
4.3.5 Carriage.
The carriage is constructed in a way that allows convenient but secure adjustment of the 10 mm height-
of-drop of the cup.
4.3.6 Motor drive (optional).
The apparatus may be equipped with a motor to turn the cam and if used shall operate at 2 ± 0,25
revolutions per second. The motor shall be isolated from the rest of the device by rubber mounts or in
some other way that prevents vibration from the motor being transmitted to the rest of the apparatus.
4.3.7 Grooving tool.
A flat or curved tool made of plastic or non-corroding-metal. The grooving tool shall have a bevelled tip
(see Annex A). The design of the tool may vary as long as the essential dimensions are maintained. The
tool may, but need not incorporate the gauge for adjusting the height-of-drop of the liquid limit device.
4.4 Plastic limit equipment
4.4.1 Mixing plate.
The mixing plate shall be flat, clean and smooth, and should be free from significant scratches which
affect the behaviour during rolling of the threads. A glass plate of about 10 mm thick and 300 mm
square has been found to be convenient.
4.4.2 Rod or gauge.
Either a rod with a diameter between 3 mm and 3,5 mm, or a gauge with an opening of the same size,
shall be used.
6 © ISO 2018 – All rights reserved

ISO 17892-12:2018(E)
5 Test procedure
5.1 Choice of liquid limit method
Two independent test methods are included in this document for the determination of the liquid limit.
The fall cone method provides results with higher repeatability, and is the preferred method. However,
there is a long history of use of the Casagrande method and its use is equally permitted.
NOTE 1 The two methods are known to give a difference in results. Experience has shown that the liquid limit
determined by the fall cone and the Casagrande apparatus are in general agreement at a w of around 30 % to
L
40 %. At higher values of w , the Casagrande apparatus generally gives slightly greater values of liquid limit. At
L
lower values of w , the Casagrande apparatus generally gives slightly smaller values of liquid limit.
L
For both liquid limit methods either a four-point test, or a one-point test, may be used. The four-point
test is described here and is preferred. However the one-point method may be appropriate in soils
whose plasticity is well understood and for which robust correlation factors have been established.
NOTE 2 In the four point liquid limit method the test is carried out at four different water contents whereas in
the one point method the test is carried out at a single water content.
The choice of test method to be used shall be agreed with the client and reported.
5.2 Specimen preparation
5.2.1 Whenever possible the tests shall be carried out on soil from its natural state. About 200 g of soil
finer than 0,4 mm is required for the determination of the liquid limit by either method. Sieves with an
aperture of 0,425 mm or an aperture of 0,400 mm are acceptable for removing the coarser material.
NOTE Where, further in this document, a 0,4 mm or nearest sieve is mentioned, sieves with an aperture of
0,425 mm or an aperture of 0,400 mm, are acceptable.
Soils should not normally be oven-dried before testing, but if this is necessary it shall be reported.
For soils that are susceptible to oxidation when exposed to air, the tests should either be determined
immediately after extrusion, or if done at a later time, the specimen shall be sealed until the test is
performed.
5.2.2 If the sample does not include material larger than about 0,4 mm, go to 5.2.8.
5.2.3 If the sample includes material larger than about 0,4 mm, this coarser fraction should be removed
as in 5.2.4 to 5.2.7.
5.2.4 Determine the water content (w) of a representative specimen of the original sample according
to ISO 17892-1.
5.2.5 Weigh a representative specimen of undried soil that will give at least 200 g of soil passing a
0,4 mm or nearest sieve. Weigh this representative specimen of undried soil to 0,1 % of its mass or 0,01 g,
whichever is the greater (m ).
5.2.6 If the fraction larger than 0,4 mm consists of a small number of discrete coarse particles, these
may be removed by hand, dried at 105 °C to 110 °C and weighed (m ).
r
5.2.7 If the coarse fraction cannot readily be removed by hand, the particles shall be removed using the
wet separation method as follows.
5.2.7.1 Place the specimen in a container and add just enough distilled water to cover it, and then stir
until it forms a slurry.
ISO 17892-12:2018(E)
5.2.7.2 Pour the slurry through a 0,4 mm or nearest sieve. A larger aperture guard sieve may be used
to protect this sieve. Wash the material retained on the sieve with a minimum amount of distilled water
until the water passing the 0,4 mm or nearest sieve is virtually clear. Retain all material passing the
0,4 mm or nearest sieve.
5.2.7.3 Dry the material retained on the 0,4 mm or nearest sieve and any guard sieve used at 105 °C to
110 °C. Weigh this dried material with an accuracy equal to 0,1 % of its mass or 0,01 g, whichever is the
greater (m ).
r
5.2.7.4 Allow the collected washings to settle and pour off any clear water.
5.2.7.5 The remaining suspension may be partially dried in a current of warm air, or in an oven at not
more than 50 °C, until it becomes a firm paste. Local drying shall be prevented at the surface or edges by
repeated stirring.
5.2.8 Remould the specimen of natural soil, hand-picked soil or sieved soil thoroughly to break down
the structure of the soil, adding or removing water as necessary to adjust the consistency of the resulting
remoulded paste to bring it into the range required of the test.
5.2.9 Remoulding should be carried out by hand using spatulas to mix the sample on the mixing plate,
and should be continued until the consistency of the specimen ceases to change. This may take up to
40 min. Avoid air bubbles being mixed into the specimen while remoulding it.
5.2.10 If a significant quantity of water needs to be added to the specimen to achieve the desired
consistency of remoulded paste, allow the specimen to equilibrate with the water for a minimum of 4 h
(taking care not to let the specimen dry in air). High plasticity soils may require up to 24 h.
5.2.11 If a significant quantity of water needs to be removed from the specimen to achieve the desired
consistency of remoulded paste, spread the whole specimen on a plate or evaporating dish and allow it to
slowly air dry, or to dry under a gentle stream of warm air. Localized drying shall be avoided by repeated
remixing of the soil.
5.2.12 The liquid limit should be determined as soon as possible after remoulding.
5.3 Determination of liquid limit by the fall cone method
5.3.1 Place portions of the prepared remoulded paste into a clean and dry cup with a spatula, taking
care not to trap air. Strike off excess soil with a straightedge to give a smooth level surface.
NOTE The liquid limit is influenced by trapping of air bubbles when remoulding or placing the paste into the
cup, or insufficient remoulding.
5.3.2 Lock the penetration cone in the raised position. Lower the supporting assembly so that the tip
of the cone just touches the surface of the soil. When the cone is in the correct position a slight movement
of the cup will just mark the soil surface.
5.3.3 Lock the penetration cone in position and either zero the depth penetration measuring device, or
record the initial position of the cone shaft to the nearest 0,1 mm.
5.3.4 Release the penetration cone and let it settle for a period of 5 s ± 1 s. If the apparatus is not fitted
with a locking device, care shall be taken not to jerk the apparatus during this operation.
5.3.5 Record the depth of penetration of the cone after 5 s ± 1 s to the nearest 0,1 mm.
8 © ISO 2018 – All rights reserved

ISO 17892-12:2018(E)
5.3.6 Calculate the depth of penetration of the cone as the difference between the initial and final
position of the cone shaft. Check that the depth of penetration is within the required range for the type
of cone in use as given in Table 3 and as shown in Figure 4. If the penetration is outside the required
range, repeat from 5.2.8 adding or removing a little water as necessary to adjust the consistency of the
remoulded paste.
5.3.7 If the depth of penetration is within the required range, lift the cone out and clean it, being careful
to avoid scratching its surface.
5.3.8 Add a little more remoulded paste to the cup, taking care not to trap air, level the surface as in
5.3.1 and repeat 5.3.2 to 5.3.7 until the difference between two successive readings is less than the value
in Table 3.
Table 3 — Cone penetration requirements
Type of cone 60 g/60° 80 g/30°
Allowable cone penetration range 7 mm to 15 mm 15 mm to 25 mm
Liquid limit (w ) determined at a penetration depth of 10 mm 20 mm
L
Maximum difference between two successive readings 0,4 mm 0,5 mm
a)  60 g/60° cone b)  80 g/30° cone
Key
1 initial position before fall
2 minimum penetration
3 penetration corresponding to w
L
4 maximum penetration
Figure 4 — Penetration range in a liquid limit fall cone test
5.3.9 Remove a specimen of minimum mass of 15 g of the remoulded paste from the zone penetrated by
the cone, and determine the water content according to ISO 17892-1 (allowing a smaller mass to be used).
5.3.10 Remove the remaining remoulded paste from the cup and add it to the rest of the remoulded
paste on the plate. Adjust the water content by a small amount, and thoroughly remix the sample with
the spatula to ensure uniform distribution of the water.
ISO 17892-12:2018(E)
5.3.11 Repeat 5.3.1 to 5.3.10 to give at least four test points at different water contents. The four points
shall all be within the range specified in Table 3, and with at least one point above and at least one point
below the penetration depth corresponding to the liquid limit. The four or more test points should be
roughly evenly spaced across the penetration range in Table 3.
5.3.12 The water content of the specimen should not be alternately increased and reduced but either
increased or reduced in stages.
NOTE It is normally more practicable to carry out the test going from the drier condition to the wetter
condition in continuously increasing water contents although going from the wetter to the drier condition is also
acceptable.
5.3.13 If at any time during the above procedure the soil has to be left for a while it shall be covered with
the evaporating dish or a damp cloth to prevent it from drying out.
5.3.14 If the one-point method is used, the penetration shall be repeated at least once. The cone
penetration measurements shall be within the allowable range and the repeated penetrations shall be
consistent in accordance with Table 3. A separate water content determination shall be made for each
penetration. If these measured water contents differ by more than 5 relative percent, the test shall be
repeated.
5.4 Determination of liquid limit by the Casagrande method
5.4.1 Place the Casagrande apparatus on a solid and level surface.
5.4.2 Add the remoulded paste to the cup with a spatula, taking care not to trap air. Press the soil down
and spread it out into the cup to a depth of at least 10 mm at its deepest point.
NOTE The liquid limit is influenced by trapping of air bubbles when remoulding or placing the paste into the
cup, or insufficient remoulding.
5.4.3 Strike off excess soil with a spatula, using as few strokes as possible, to give a smooth surface of
10 mm depth at its deepest point, tapering to form an approximately horizontal surface. This is shown
schematically in Figure 5a) in cross section and Figure 5b) in plan.
10 © ISO 2018 – All rights reserved

ISO 17892-12:2018(E)
a)  Cross section b)  Plan
Key
1 cup
2 surface level for test
3 principle sketch of profiled side of groove as cut
4 base of cup exposed by groove as cut
5 10 mm closure of groove at end point of test
A 10 mm
Figure 5 — a) Filling the cup with soil, b) cup at the end of the test
5.4.4 Use the grooving tool to cut a groove in the soil paste, exposing the face of the cup at the base of
the groove. The grooving tool shall be clean and dry, and shall be kept perpendicular to the inner surface
of the cup with the bevelled edge facing the direction of movement.
5.4.5 If the specimen is clay, the groove should be cut in a single stroke. If the specimen is silt, several
cuts may be required, taking away a small amount of the specimen with each stroke. While cutting the
groove, ensure that the specimen does not slide across the face of the cup, nor crack.
5.4.6 Lift and drop the cup onto the base by rotating the cam at about 2 revolutions per second. Do not
hold the base while rotating the cam.
5.4.7 Count the number of rotations while carefully observing the groove cut in the soil. The gap should
close by soil flowing, rather than by soil sliding across the surface of the cup.
5.4.8 Stop rotating the cam as soon as the groove has closed over a length of 10 mm (Figure 5b). Record
the number of rotations.
ISO 17892-12:2018(E)
5.4.9 Check that the number of rotations is within the required range as given in Table 4. If the number
is outside the required range, repeat 5.2.8 to 5.2.12, adding or removing a little water as necessary to
adjust the consistency of the remoulded paste, and then repeat the measurement from 5.4.1.
Table 4 — Casagrande test requirements
Number of rotations
Range of number of rotations 15 to 40
Number of rotations to determine liquid limit (w ) 25
L
Maximum difference between two successive readings for a one-point test 2
5.4.10 Remove a specimen of at least 15 g of the remoulded paste from the zone where the groove has
closed, and determine the water content according to ISO 17892-1 (allowing a smaller mass to be used).
5.4.11 Remove the remaining remoulded paste from the cup and add it to the rest of the remoulded
paste on the plate. Adjust the water content by a small amount, and thoroughly remix the sample with
the spatula to ensure uniform distribution of the water.
5.4.12 Repeat 5.4.1 to 5.4.11 to give at least four test points at different water contents, cleaning and
thoroughly drying the cup between each. The four points shall all be within the range specified in Table 4,
and with at least one point above and at least one point below 25 rotations. The four or more test points
should be roughly evenly spaced across the rotation count range in Table 4.
5.4.13 The water content of the specimen should not be alternately increased and reduced but either
increased or reduced in stages.
NOTE It is normally more practical to carry out the test going from the drier condition to the wetter
condition in continuously increasing water contents although going from the wetter to the drier condition is also
acceptable.
5.4.14 If at any time during the above procedure the soil has to be left for a while it shall be covered with
the evaporating dish or a damp cloth to prevent it from drying out.
5.4.15 If the one-point method is used, the counting of the number of rotations for the closure of the
groove over a length of 10 mm shall be repeated at least once. The specimen shall be removed from the
cup and remoulded between tests. The rotation counts for the two or more determinations shall comply
with the range of values given in Table 4, and the repeated results shall be consistent as also specified
in Table 4. If the water contents measured in the separate determinations differ by more than 5 relative
percent, the test shall be repeated.
5.5 Determination of plastic limit
5.5.1 Take a specimen of about 15 g to 20 g of the soil paste prepared according to 5.2, and place it on
the mixing plate.
NOTE It is often convenient to carry out the test on a portion of the material prepared for one of the liquid
limit tests procedures.
5.5.2 Allow the remoulded paste to partially dry on the plate until it becomes plastic enough to be
shaped into a ball. The specimen may be air-dried, or dried under a gentle stream of warm air.
5.5.3 Mould the ball of partially dried paste between the fingers and roll it between the palms of the
hands until the heat of the hands has dried the soil sufficiently for slight cracks to appear on its surface.
Divide the ball into two portions of about equal mass.
12 © ISO 2018 – All rights reserved

ISO 17892-12:2018(E)
5.5.4 Divide one portion into 3 sub-portions.
5.5.5 One sub-portion at a time, mould each into a thread about 6 mm diameter between the first
finger and thumb of each hand.
5.5.6 Place the thread on the mixing plate and roll it backwards and forwards with an even motion of
the hand. Rolling between the fingers of one hand, from finger-tip to the second joint has proven to be
good practice. Maintain a gentle uniform downwards pressure and roll the thread in such way that the
whole thread gets an even thickness, until its diameter approaches 3 mm. If required, use the 3 mm rod
or gauge to assess the diameter of the thread.
5.5.7 Repeat 5.5.5 to 5.5.6 until the thread crumbles when it has been rolled to 3 mm diameter. The
correct end-point of the test is when the threads just begin to break apart, rather than when they begin
to crack.
5.5.8 Place the crumbled pieces of thread into a suitable container and place a lid on it.
5.5.9 Repeat 5.5.5 to 5.5.7 on the other two sub-portions of partially dried remoulded paste, placing all
the crumbled pieces of thread from all three sub-portions into the same container. Determine the water
content of the crumbled threads according to ISO 17892-1.
5.5.10 Repeat 5.5.4 to 5.5.9 on the second portion of partially dried remoulded paste at 5.5.3, placing
the crumbled threads from these three sub-portions into a second container, and determine the water
content of the crumbled threads according to ISO 17892-1.
5.5.11 Some soils have very low plasticity, and it can be difficult to assess the precise crumbling
condition. If it is not possible to roll 3 mm threads, the sample should be reported as non-plastic.
6 Test results
6.1 Proportion of sample smaller than 0,4 mm
If particles have been removed from the specimen, estimate the percentage of material smaller than
0,4 mm (K) from Formula (1):
 
 
100×m
  −m 
r
 
 100 +w 
 
 
K = ×100% (1)
 
100×m
 
 
100 +w
 
where
w is the water content of the separate representative specimen, in per cent;
m is the mass of undried soil (g);
m is the dry mass of coarse particles greater than 0,4 mm removed (g).
r
6.2 Liquid limit by the fall cone method
6.2.1 Plot the measured water contents as ordinate on a linear scale, and the corresponding cone
penetrations as abscissa on a log10 scale if using the 60 g/60° cone. If using the 80 g/30° cone, plot both
ISO 17892-12:2018(E)
water content and cone penetration on linear scales. An example plot for a 60 g/60° cone is shown in
Figure 6.
Key
X cone penetration (mm)
Y water content (%)
Figure 6 — Example of a liquid limit test result from a fall cone test with the 60 g cone
6.2.2 Draw the best straight-line fit through the plotte
...