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Issue 1 January 2005

DATA
SHEET
New mortar standards
19

Introduction
On the 31st of January 2005 the existing BS mortar and associated test method standards
were withdrawn and replaced by harmonized European Product Standards and common test
methods. In addition a revised British Standard covering those mortar test methods that are
not part of the new European Standards, but which it is desired to retain, will be published.

Standards/documents withdrawn

BS 4721:1981 Specification for ready-mixed building mortars

BS 5838-2:1980 Specification for dry packaged cementitious mixes - Pre-packed

mortar mixes

BS 4551: Methods of testing mortars screeds and plasters which is currently

published in two parts is being republished as a single part Standard with
the same Standard number. A multi part Standard on mortar testing has
been published as BS EN 1015

PD 6472 Guide to specifying the quality of building mortars

Standards/documents adopted

A new two part harmonized product Standard for mortar was published in 2003.

BS EN 998-1 Specification for mortar for masonry - Part 1: Rendering and

plastering mortar

BS EN 998-2 Specification for mortar for masonry - Part 2: Masonry mortar

PD 6678 Guide to the selection and specification of masonry mortar

These documents are applicable to all mortars. However when applied to site mixed mortars
they must be used in conjunction with the existing National Standard BS 5628. It should be
noted that the Standards are not applicable when calcium sulfate is used as the principal
binding agent.

Examination of the new mortar Standards shows that they have been written using the
performance concept, this is a departure from the traditional UK practice, which has been
based primarily on a prescription (recipe) approach. The recipe approach is based on the
producer of the mortar batching prescribed proportions of materials, the performance concept
requires the producer of the mortar to achieve a stated performance and allows the producer
freedom to select the mix proportions to achieve this.

Historically recipes for screed materials have been listed in section 4 of BS 4721 and screed
material testing covered by BS 4551. Screed materials are no longer within the scope of the
mortar Standards and a separate series of Standards cover these products:
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BS EN 13318: Screed material and floor screeds - Definitions

BS EN 13813: Screed material and floor screeds - Screed material - Properties

and requirements

Screed material testing is covered by BS EN 13892, which is published in eight parts. This
data sheet does not discuss the new screed Standards.

Terminology
The introduction of the new Standards will result in the use of a number of new terms these
include:

• Attestation system - this is the term used to describe the degree of involvement of third
parties or the producer in assessing the conformity of the product in accordance with the
technical specification.

• CE marking - this mark signifies that a product conforms to a harmonized European

technical specification (European Standard or European Technical approval). Annex ZA of
the relevant Standard lists the technical requirements for CE marking, for a product for a
designated end use. Currently CE marking is not mandatory in the UK.

• Declared value - a value that the manufacturer is confident in achieving, bearing in mind
the precision of the test and variability of the process.

• Evaluation of conformity - a systematic examination of the extent to which a product fulfils

specified requirements.

• Harmonized Standard - a European Standard (EN) prepared under the mandate of the
European Commission with the purpose of supporting a directive. A directive defines
generic safety requirements.

• Initial type test - prior to placing a product on the market and when changes occur either in
the constituent materials or production process which could affect the characteristics of the
product, initial type testing, must be undertaken.

The initial type tests that are necessary for each product are listed within the individual
Standards.

• Mandate - a formal request from the European commission to CEN (European Standards
Organisation) to prepare a Standard.
Classification of Mortars
Both parts of BS EN 998 classify mortar in three different ways, the classification system is
shown in Table 1.

Table 1: Classification of mortar

BS EN 998-1 - Rendering/plastering mortar BS EN 998-2 - Masonry mortar

According to (i) Factory made (i) Factory made

location of (ii) Semi-finished (ii) Semi finished
manufacture (iii) Site made (iii) Pre-batched
(iv) Premixed lime sand
(v) Site made

According to (i) Designed (i) Designed

concept (ii) Prescribed (ii) Prescribed

According to (i) General purpose (GP) (i) General purpose (G)

properties (ii) Lightweight* (LW) (ii) Thin layer† (T)
and uses (iii) Coloured (CR) (iii) Lightweight (L)
(iv) One coat for external use (OC)
(v) Renovation# (R)
(vi) Thermal Insulating (T)

* A lightweight mortar is required to have a dry hardened density of less than 1300kg/m3
† A thin layer masonry mortar is required to have a maximum aggregate particle size of 2mm
# A renovation rendering mortar is designed for use on moist masonry walls containing soluble salts

Materials
The European Standards for both rendering mortars and masonry mortars require that
constituent raw materials shall have characteristics which permit the finished product to
conform to the requirements of the Standard. The European Standards require that
constituent materials of established suitability be used.
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Rendering Mortar (BS EN 998-1)

The manufacturer of the mortar is required to declare the workable life when the mortar
contains an admixture to control the setting, testing should be undertaken in accordance with
BS EN 1015-9. It is a requirement of the Standard that the air content be tested and declared
when relevant to the end use of the mortar.

The requirements for hardened rendering and plastering mortar are set out in Table 2.

Table 2: Classification for hardened rendering and plastering mortars

Property Type Mean values

Compressive strength at 28 days CS.I 0, 4 - 2, 5N/mm2

CS.II 1, 5 - 5, 0N/mm2
CS.III 3, 5 - 7, 5N/mm2
CS.IV > 6N/mm2

Capillary water absorption W0 Not specified

W1 c ≤ 0, 40kg/m2 min 0, 5

W2 c ≤ 0, 20kg/m2 min 0, 5

Thermal conductivity T1 ≤ 0, 1W/m.K

T2 ≤ 0, 2W/m.K

Table 3 lists the requirements for each of the classifications for rendering and
plastering mortar.

Manufacturers may declare density values for hardened plastering and rendering mortar when
appropriate. Testing shall be carried out in accordance with BS EN 1015-10.

A manufacturer may if he wishes declare a value where a dash is indicated in a box.

There is a durability requirement for the determination of water penetration after completion of
the capillary water absorption test, this is required to be undertaken in accordance with
BS EN 1015-18 for One Coat rendering mortar (OC).
Table 3: Requirements for hardened plastering and rendering mortar

Type of Mortar

Test Parameter Method of test GP LW CR OC R T

Dry bulk density BS EN 1015-10 Declared Declared Declared Declared Declared Declared
(kg/m3) range of range of range of range of range of range of
values values ≤ values values values values
1300
kg/m3
Compressive strength BS EN 1015-11 CS I-IV CS I-III CS I-IV CS I-IV CS II CS I-II
(categories)
Adhesion (N/mm2 BS EN 1015-12 ≥ ≥ ≥ ≥ ≥
and fracture pattern Declared Declared Declared Declared Declared
(FP) A, B or C) value and value and value and - value and value and
fracture fracture fracture fracture fracture
pattern pattern pattern pattern pattern
Adhesion after BS EN 1015-21 Declared
weathering cycles value and
(N/mm2 and fracture - - - fracture - -
pattern (FP) A, B or C) pattern
Capillary water BS EN 1015-18 W0-W2 W0-W2 W0-W2 W1-W2 ≥0.3kg/m2 W1
absorption after 24
(kg/(m2.h.0.5). For hours
mortars intended to
be used in external
elements
Water penetration BS EN 1015-18 ≤5mm
after capillary water
absorption test - - - - -
(in mm)
Water permeability on BS EN 1015-21 ≤1ml/cm2
relevant substrates after 48
after weathering - - - hours - -
cycles (ml/cm2 after
48 hours)
Water vapour BS EN 1015-19 ≤ ≤ ≤ ≤ ≤15 ≤15
permeability Declared Declared Declared Declared
coefficient (µ) for value value value value
mortars intended to
be used in external
elements
Thermal conductivity BS EN 1745 Tabulated Tabulated Tabulated Tabulated Tabulated
(W/m.k) : 2002 Table value value value value value
A.12
For mortars intended BS EN 1745 T1≤0, 10
to be used in : 2002 4.2.2 T2≤0, 20
elements subject to - - - - -
thermal requirements
Reaction to fire BS EN 13501-1 The Standard states that where the mass or volume fraction (whichever
(class) is the most onerous) of organic material is less than 1.0% the mortar
may be classified as reaction to fire Class A1 without the need for test,
this provision is also applicable to masonry mortar conforming to
BS EN 998-2. Where the volume or mass of organic matter is greater
than 1.0% testing in accordance with BS EN 13501-1 shall be
undertaken

Durability No requirements for durability are prescribed except for one coat
rendering mortars where adhesion and water permeability after
weathering cycles has to be assessed
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Masonry mortar (BS EN 998-2)

a The requirements for the properties of fresh masonry mortar are set out in Table 4. The
mortar should be sampled in accordance with BS EN 1015-2.

Table 4: Requirements for fresh properties of masonry mortar

Property Test Requirement

Workable life BS EN 1015-9 ≥ Declared value

Chloride content (i) BS EN 1015-17 ≤ Declared value
Air Content (ii) BS EN 1015-7 Within declared range

Note
(i) The chloride content shall not exceed 0,1% Cl of the mortar by dry mass, the chloride content may also be
calculated based on the chloride ion content of the individual constituent materials.
(ii) The Standard does not prescribe limits for the air content

b For thin layer mortars the correction time determined in accordance with BS EN 1015-9
shall be declared.

c For designed Masonry mortars, the compressive strength classes are:

M1, M2,5, M5, M10, M15, M20. It is possible to have further strength classes above M20,
where the manufacturer may declare other values in class Md. The compressive strength
shall be determined on samples taken in accordance with BS EN 1015-2 and tested in
accordance with BS EN 1015-11. It should be noted that the compressive strength classes
are different to those adopted for traditional mortar designations as shown in the National
Annex to BS EN 998-2.

d Other hardened properties of masonry mortar may have to be declared depending on the
proposed end use of the mortar. Table 5 summarises these:

Table 5: Requirements for properties of hardened masonry mortar

Property Performance level Test method Requirement to provide data

Bond strength Declared value BS EN 1052-3, alternatively a Only applicable to designed

tabulated value in accordance with masonry mortar subjected to
Annex C of BS EN 998-2 may be structural requirements
declared
Water absorption Declared value BS EN 1015-18 Only applicable to masonry mortar
used in external situations
Water vapour Declared value Calculation of tabulated values in Only applicable to masonry mortar
permeability accordance with BS EN 1745 used in external situations
Annex A, Table 12
Dry density of Declared value BS EN 1015-10 When relevant to the use for which
hardened mortar the mortar is placed on the market
Thermal Declared value BS EN 1745, Table A12 Only applicable to masonry mortars
conductivity alternatively measured values in subject to thermal requirements
accordance with BS EN 1745
Clause 4.2.2 may be declared
e For prescribed masonry mortars the proportions shall be declared. Additionally the
relationship between the compressive strength and the mix proportions shall be declared
using publicly available references, establishing the relationship between mix proportions
and compressive strength. The informative National Annex NA of BS EN 998-2
incorporates a Table showing the traditional BS 4721 Designations and the comparative
mortar class. This is reproduced as Table 6.

Table 6: Traditional designations and the new mortar classes

BS 4721 - Traditional mix designations BS EN 998-2 - Mortar class*

i 12
ii 6
iii 4
iv 2

*It should be noted that the new mortar classes relate to prism strengths

Attestation of conformity
European legislation prescribes different levels of attestation of conformity which relate to
product end use and relevant design and safety criteria. There are six levels, each one defines
the tasks that must be undertaken by the manufacturer/Notified Body (generally a third party
certification body). The applicable levels for mortar products are:

Rendering mortar and prescribed masonry mortar - Level 4

Designed masonry mortar - Level 2+

Table 7 shows the requirements for these levels.

Table 7: Attestation of conformity systems

Conformity numbering system 2+ 4

Tasks for the manufacturer

Factory production control √ √
Extra testing of samples taken from the production unit (factory) in accordance with a
prescribed test plan √ −
Initial type testing √ √

Tasks for the notified body

Initial type testing − −
Initial certification of factory production control (FPC) √ −
Continuous surveillance of factory production control (FPC) √ −
Audit testing of samples taken from the factory or the market place or site − −

√ = Task required
Testing
It was stated in the introduction that mortar testing is covered by the BS EN 1015 series of
test methods, these are listed in Table 8 below. The revised version of BS 4551 will cover the
procedures for undertaking two physical tests where no conflicting European Standard has
been published:
• Determination of consistence by dropping ball
• Determination of consistence retentivity and water retentivity
In addition it will contain the methods of chemical analysis, this subject area has not yet been
addressed with the European Standardization work programme.

Table 8: BS EN 1015 - Methods of test for mortar for masonry

Part 1 Determination of particle size distribution (by sieve analysis)
Part 2 Bulk sampling of mortars and preparation of test mortars
Part 3 Determination of consistence of fresh mortar (by flow table)
Part 4 Determination of consistence of fresh mortar (by plunger penetration)
Part 6 Determination of bulk density of fresh mortar
Part 7 Determination of air content of fresh mortar(i)
Part 9 Determination of workable life and correction time of fresh mortar
Part 10 Determination of dry bulk density of hardened mortar
Part 11 Determination of flexural and compressive strength of hardened mortar
Part 12 Determination of adhesive strength of hardened rendering and plastering mortar on substrates
Part 17 Determination of water-soluble chloride content of fresh mortar
Part 18 Determination of water absorption due to capillary action of hardened mortar
Part 19 Determination of water vapour permeability of hardened rendering and plastering mortar
Part 21 Determination of the compatibility of one-coat rendering mortar with backgrounds (through
assessment of adhesive strength and water permeability after conditioning)

(i) For rendering and masonry mortars made with porous aggregates the air content may be determined according to
BS EN 1015-6 (fresh mortar density)

There are some gaps in the sequence of the part numbers, this has arisen because a number
of work items that had been allocated part numbers have either been dropped from the work
programme or work on them has been suspended for the present. It should be noted that not
all the test methods are called up by the Product Standards.

There is a real danger of contact dermatitis or serious burns if skin comes into contact with wet
mortar. Wear suitable protective clothing and eye protection. Where skin contact occurs either directly
or through saturated clothing wash immediately with soap and water. For eye contact immediately
wash out eyes thoroughly with clean water. If swallowed wash out mouth and drink plenty of water.
The relevant codes of practice, standards and statutory regulations must always be observed.
The information in this data sheet may be freely copied with acknowledgement to the Mortar Industry
Association. Current issue numbers of all MIA publications are available from the MIA website.

Mortar Industry Association

Gillingham House 38 - 44 Gillingham Street London SW1V 1HU Tel +44 (0)20 7963 8000 Fax +44 (0)20 7963 8001

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