FprEN ISO 16383-2

• Abstract:

  This document will specify methods for the determination of the bulk density of rock.; This document is applicable to the laboratory determination of the bulk density of rock samples

• Status: Not Published
• Publication Date: 10-Mar-2027
• ICS: 13.080.40 - Hydrological properties of soils
• ICS: 93.020 - Earthworks. Excavations. Foundation construction. Underground works
• Technical Committee: CEN/TC 341 - Geotechnical Investigation and Testing
• Drafting Committee: CEN/TC 341 - Geotechnical Investigation and Testing
• Current Stage: 4599 - Dispatch of FV draft to CMC - Finalization for Vote
• Start Date: 29-Jun-2026
• Due Date: 30-Nov-2025
• Completion Date: 29-Jun-2026
• Ref Project: oSIST prEN ISO 16383-2:2026 - Geotechnical investigation and testing - Laboratory testing of rock - Part 2: Determination of density and open porosity (ISO/DIS 16383-2:2026)

• Referred By: EN 60601-1:2006/A1:2013 - Medical electrical equipment - Part 1: General requirements for basic safety and essential performance
• Effective Date: 09-Feb-2026
• Referred By: EN ISO 25539-3:2024 - Cardiovascular implants - Endovascular devices - Part 3: Vena cava filters (ISO 25539-3:2024)
• Effective Date: 28-Jan-2026
• Referred By: EN ISO 10993-10:2023 - Biological evaluation of medical devices - Part 10: Tests for skin sensitization (ISO 10993-10:2021)
• Effective Date: 28-Jan-2026
• Referred By: EN ISO 10993-1:2025 - Biological evaluation of medical devices - Part 1: Requirements and general principles for the evaluation of biological safety within a risk management process (ISO 10993-1:2025)
• Effective Date: 28-Jan-2026
• Referred By: EN ISO 16671:2025 - Ophthalmic implants - Irrigating solutions for ophthalmic surgery (ISO 16671:2025)
• Effective Date: 28-Jan-2026
• Referred By: EN ISO 21649:2023 - Needle-free injection systems for medical use - Requirements and test methods (ISO 21649:2023)
• Effective Date: 28-Jan-2026
• Referred By: EN ISO 12417-1:2024 - Cardiovascular implants and extracorporeal systems - Vascular device-drug combination products - Part 1: General requirements (ISO 12417-1:2024)
• Effective Date: 28-Jan-2026
• Referred By: EN ISO 7405:2025 - Dentistry - Evaluation of biocompatibility of medical devices used in dentistry (ISO 7405:2025)
• Effective Date: 28-Jan-2026
• Consolidated By: ISO/FDIS 16383-2 - Geotechnical investigation and testing — Laboratory testing of rock — Part 2: Determination of density and open porosity
• Effective Date: 12-Feb-2026

FprEN ISO 16383-2 is a CEN draft standard for geotechnical investigation and testing. It specifies laboratory methods for determining the bulk density of rock specimens, and also covers dry density, grain density and open porosity. The document is aimed at laboratories and geotechnical professionals who need repeatable density and porosity results from rock samples.

What does FprEN ISO 16383-2 specify?

FprEN ISO 16383-2 applies to the laboratory determination of density and open porosity of rock test specimens within geotechnical investigations. Clause 1 makes the main test routes the immersion method and a combination of the linear method and gas pycnometry.

The document is organized into clauses on scope, references, terms, symbols, equipment, procedure, results and reporting, followed by two annexes. Annex A gives calibration, maintenance and checking requirements, while Annex B lists other volume-determination methods that may be suitable if they satisfy the document's requirements.

Annex	What it covers
Annex A	Calibration, maintenance and checks for the equipment used in the test
Annex B	Volume determination options beyond immersion, linear measurement and gas pycnometry

Clause 1 also states that other methods for bulk mass, grain mass, bulk volume and grain volume may be acceptable if they meet the requirements in the document. In practice, that gives laboratories some flexibility, but only when the alternative method can deliver comparable accuracy and is documented properly.

What are the key requirements of FprEN ISO 16383-2?

Specimens must be representative and prepared consistently

Clause 6 requires a representative specimen selected by a qualified person. The specimen should weigh at least 50 g and be large enough relative to the rock's grain or pore size, because a too-small specimen can give misleading density and porosity results.

For the linear method, the specimen must be shaped as a right circular cylinder or a rectangular cuboid, with faces level and perpendicular within the stated tolerances. The specimen also has to be cleaned without damage, and it must be fully saturated with the immersion liquid before bulk mass and submerged mass are measured.

The document defines the equipment and its calibration

Clause 5 lists the equipment needed: straight edge, callipers, balance, gas pycnometer, drying oven, temperature and humidity measuring devices, specimen container and desiccator. Annex A adds the calibration and checking rules for that equipment.

This matters because the method depends on small mass, length, temperature and pressure measurements. If the balance, oven or pycnometer is not controlled, the density and porosity values will not be reliable.

Two measurement routes are allowed

Clause 6 describes the immersion method and the linear method combined with gas pycnometry. The immersion route uses bulk mass, grain mass and submerged mass; the alternative route uses measured specimen dimensions for bulk volume and gas pycnometry for grain volume.

Clause 6 also requires grain mass to be determined after drying to constant mass. For some rocks, such as gypsum-bearing material or other rocks with chemically bonded water, drying may need to be done below 60 °C so that the result reflects the intended dry mass without unnecessary mineral change.

The procedure controls moisture and buoyancy effects

Clause 6 requires careful handling when the specimen is weighed submerged in the immersion liquid. The liquid surface must be allowed to settle, air bubbles must not be trapped, and the ambient temperature and immersion liquid temperature must be recorded.

Clause 7 notes that the immersion calculations assume closed pores have a net zero effect on buoyancy. The document also fixes the water density value used in calculations and notes that water temperature should be reported if it differs significantly from 20 °C.

Results are reported as density values and open porosity

Clause 7 sets out the calculations for bulk density, grain density, dry density and open porosity for both method routes. It also provides separate equations for right circular cylinders and rectangular cuboids when the linear method is used.

In practice, that means the laboratory must choose the correct calculation path for the specimen shape and test method, then report the final values clearly and consistently. Clause 8 requires the report to state the method used, specimen identification, geological description, shape and size, the standard reference, the results, water content, environmental conditions, and any deviations or special events.

Alternative volume methods may be used if justified

Annex B lists fluid displacement, glass bead, laser volumetry, acoustic volumetry, 3D scanning and tomography as possible volume-determination methods. If a laboratory uses one of these instead of the stated methods, the report has to identify the deviation and the method must still satisfy the document's performance expectations.

What terms does FprEN ISO 16383-2 define?

• Saturation fluid - the fluid used to saturate the specimen; the document says it must be reported.
• Immersion liquid - the liquid the specimen is placed in during immersion measurements, typically water.
• Open void - a void that the saturation fluid can penetrate.
• Closed void - a void that the saturation fluid cannot penetrate.
• Grain volume - the volume of the rock matrix, including closed voids but excluding open voids.
• Bulk volume - the total volume of the specimen, including the rock matrix and both open and closed voids.
• Bulk density - the bulk mass divided by the bulk volume; also called apparent density.
• Dry density - the grain mass divided by the bulk volume.
• Grain density - the grain mass divided by the grain volume; also called matrix density or particle density.
• Open porosity - the ratio of void volume to bulk volume.
• Constant mass - the point where further drying changes mass by less than 0.1 % over three consecutive measurements.
• Representative specimen - a specimen chosen by a qualified person to reflect the characteristic features of the rock mass.

Who uses FprEN ISO 16383-2?

FprEN ISO 16383-2 is used by geotechnical laboratories, rock testing technicians, engineers and quality managers who need density and open porosity data for rock specimens. It is relevant to geotechnical investigation, earthworks, excavation, foundation construction and underground works.

It is also useful for projects where rock properties must be documented in a standard way for design records, laboratory comparisons or contract testing. Because the report has to include specimen description, environmental conditions and deviations, the document supports traceable test records as well as test execution.

Which standards are used with FprEN ISO 16383-2?

• ISO 14689 - used for the visual geological description of the tested specimen and for recording observed features after testing.
• ISO 16383-1 - used for water content and for the constant-mass drying approach referenced in the definitions and test procedure.
• ISO 12154 - used for gas pycnometry and the determination of grain volume in the alternative method route.

What does the FprEN ISO 16383-2 document contain?

Clause 4 gives the symbols and units used in the equations. Clause 5 specifies the measuring equipment and its performance needs, including the gas pycnometer, balance, oven, callipers, hygrometer and desiccator.

Clause 6 presents flow charts for the two test routes and breaks the procedure into specimen preparation, bulk mass, grain mass, submerged mass, bulk volume and grain volume. Clause 7 then gives the calculation formulas for bulk density, grain density, dry density and open porosity for both cylindrical and rectangular specimens.

Clause 8 defines the report content, including method used, specimen identification, geological description, test conditions, results and any deviations. Annex A adds calibration and checking rules, including annual calibration for several instruments and daily checks for balances, while Annex B lists alternative approaches to volume determination for cases where the stated methods are not used.

SLOVENSKI STANDARD
01-marec-2026
Geotehnično preiskovanje in preskušanje - Laboratorijsko preskušanje kamnin - 2.
del: Ugotavljanje gostote in odprte poroznosti (ISO/DIS 16383-2:2026)
Geotechnical investigation and testing - Laboratory testing of rock - Part 2: Determination
of density and open porosity (ISO/DIS 16383-2:2026)
Geotechnische Erkundung und Untersuchung - Laborversuche an Felsproben - Teil 2:
Bestimmung der Rohdichte und der offenen Porosität (ISO/DIS 16383-2:2026)
Reconnaissance et essais géotechniques - Essais de laboratoire sur les roches - Partie
2: Détermination de la masse volumique et de la porosité ouverte (ISO/DIS 16383-
2:2026)
Ta slovenski standard je istoveten z: prEN ISO 16383-2
ICS:
13.080.40 Hidrološke lastnosti tal Hydrological 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.

DRAFT
International
Standard
ISO/DIS 16383-2
ISO/TC 182
Geotechnical investigation and
Secretariat: BSI
testing — Laboratory testing of
Voting begins on:
rock —
2026-01-12
Part 2:
Voting terminates on:
2026-04-06
Determination of density and open
porosity
ICS: 13.080.40; 93.020
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
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Reference number
ISO/DIS 16383-2:2026(en)
DRAFT
ISO/DIS 16383-2:2026(en)
International
Standard
ISO/DIS 16383-2
ISO/TC 182
Geotechnical investigation and
Secretariat: BSI
testing — Laboratory testing of
Voting begins on:
rock —
Part 2:
Voting terminates on:
Determination of density and open
porosity
ICS: 13.080.40; 93.020
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
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Published in Switzerland Reference number
ISO/DIS 16383-2:2026(en)
ii
ISO/DIS 16383-2:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and units. 3
5 Equipment . 4
5.1 General .4
5.2 Straight edge.4
5.3 Callipers .4
5.4 Balance .4
5.5 Gas pycnometer .4
5.6 Drying oven .4
5.7 Thermometer or thermocouple device .4
5.8 Relative humidity .4
5.9 Test specimen container .4
5.10 Desiccator.5
6 Test procedure . 5
6.1 General .5
6.1.1 Specimen size requirements .5
6.1.2 Test specimen preparation .6
6.2 Determination of bulk mass .6
6.3 Determination of grain mass .6
6.4 Determination of submerged mass using the immersion method .7
6.5 Determination of bulk volume using the linear method .8
6.6 Determination of grain volume using gas pycnometry .9
7 Test results . .10
7.1 Immersion method . . .10
7.1.1 Bulk density .10
7.1.2 Grain density .10
7.1.3 Dry density .10
7.1.4 Open porosity .11
7.2 Linear method combined with gas pycnometry .11
7.2.1 Bulk density .11
7.2.2 Grain density .11
7.2.3 Dry density . 12
7.2.4 Open porosity . 12
8 Test report .13
Annex A (Normative) Calibration, maintenance, and checks . 14
Annex B (Informative) Volume determination .16
Bibliography . 17

iii
ISO/DIS 16383-2:2026(en)
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 Technical Committee ISO/TC 182, [Geotechnical investigation and testing],
Subcommittee WG 10, [Laboratory testing of rock].
A list of all parts in the ISO 16 383 series can be found on the ISO website.

iv
ISO/DIS 16383-2:2026(en)
Introduction
This document covers areas in the international field of geotechnical engineering never previously
standardized internationally. It is intended that this document presents broad good practice throughout the
world and significant differences with national documents is not anticipated. It is based on international
practice (see Reference [1]).
v
DRAFT International Standard ISO/DIS 16383-2:2026(en)
Geotechnical investigation and testing — Laboratory testing
of rock —
Part 2:
Determination of density and open porosity
1 Scope
This document specifies the procedure for determining bulk, dry and grain densities as well as open porosity
of a rock specimen using the immersion method and a combination of the linear method and gas pycnometry.
This document is applicable to the laboratory determination of density and open porosity of a rock test
specimen within the scope of geotechnical investigations.
Other methods for determining the bulk mass, grain mass, bulk volume and grain volume of the specimen
that fulfil the requirements set in this document may also be considered acceptable (Annex B). Used method
should be chosen based on the use case (type of specimen, availability etc.).
Bulk, dry and grain density as well as open porosity are determined for the specimen as is and are dependent
on fluid content, which shall be determined and reported as per ISO 16383-1.
NOTE This document fulfils the requirements of the determination of bulk density of rock for geotechnical investigation
and testing in accordance with EN 1997-2 (2024).
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 14689, Geotechnical investigation and testing — Identification, description and classification of rock
ISO 16383-1, Geotechnical investigation and testing — Laboratory testing of rock — Part 1: Determination of
water content
ISO 12154, Determination of density by volumetric displacement — Skeleton density by gas pycnometry
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
Saturation fluid
the fluid used to saturate the specimen
Note 1 to entry: saturation fluid must be reported.

ISO/DIS 16383-2:2026(en)
3.2
Immersion liquid
the liquid the specimen is immersed in, typically water
Note 1 to entry: immersion liquid must be reported.
3.3
Open void
void that can be penetrated by the saturation fluid
3.4
Closed void
void that cannot be penetrated by the saturation fluid
3.5
Void volume
volume of open voids
3.6
Grain volume
volume of the rock matrix, including closed voids, but excluding open voids
3.7
Grain mass
mass of the rock matrix, including closed voids, but excluding open voids
3.8
Bulk volume
total volume of the specimen, including the rock matrix, and open and closed void volumes
3.9
Bulk mass
total mass of the specimen, including the rock matrix, and open and closed void volumes
3.10
Submerged mass
total mass of the specimen, including the rock matrix, and open and closed void volumes, submerged in the
immersion liquid
3.11
Water density
density of water, a constant value of 0,998 2 g/cm corresponding to the density of pure water at 20 °C
(IAPWS95-2018) is used in this document
3.12
Immersion liquid density
density of the immersion liquid
3.13
Water content
ratio of the mass of free water to the mass of the dry specimen, to be determined as per ISO 16383-1
3.14
Density
mass of a substance per unit of volume, also known as specific mass
3.15
Specific gravity
ratio of the density of a substance to the density of a given reference material, typically water at its densest
(at 4 °C), also known as relative density

ISO/DIS 16383-2:2026(en)
3.16
Bulk density
bulk mass of the rock specimen divided by its bulk volume, also known as apparent density
3.17
Dry density
grain mass of the rock specimen divided by its bulk volume
Note 1 to entry: specimen is considered fully dried when it has been dried to a constant mass as per ISO 16383-1.
3.18
Grain density
grain mass of the rock specimen divided by its grain volume, also known as matrix density or particle density
3.19
Open porosity
the ratio of void volume to bulk volume
3.20
Constant mass
the point at which there is less than 0,1 % further change in mass of the rock test specimen when dried for a
further period of at least 1 h, over three consecutive measurements, as described in ISO 16383-1
3.21
Representative specimen
a specimen chosen by a qualified person associated with the characteristic features of the rock mass
4 Symbols and units
V void volume (cm )
V
V grain volume (cm )
G
M grain mass (g)
G
V bulk volume (cm )
M bulk mass (g)
M submerged mass (g)
S
ρ water density (g/cm )
W
ρ immersion liquid density (g/cm )
L
w water content (%)
r radius of the specimen (cm)
h height of the specimen (cm)
L length of the longest dimension of the specimen (cm)
L length of the second longest dimension of the specimen (cm)
L length of the shortest dimension of the specimen (cm)
V volume of the sample chamber (cm )
V volume of the reference chamber (cm )
ISO/DIS 16383-2:2026(en)
p equilibrated gauge pressure prior to expansion (Pa)
p equilibrated gauge pressure after expansion (Pa)
ρ bulk density (g/cm )
ρ grain density (g/cm )
G
ρ dry density (g/cm )
D
P open porosity (%)
NOTE Here r refers to the radius of a cylindrical or spherical specimen, h refers to the height of a cylindrical specimen,
and L , L and L refe
...