CEN/TR 15739:2008

SLOVENSKI STANDARD
01-marec-2009
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Precast concrete products - Concrete finishes - Identification
Produits préfabriqués en béton - Surface et parements de béton - Éléments
d'identification
Ta slovenski standard je istoveten z: CEN/TR 15739:2008
ICS:
91.100.30 Beton in betonski izdelki Concrete and concrete
products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
CEN/TR 15739
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
December 2008
ICS 91.100.30
English Version
Precast concrete products - Concrete finishes - Identification
Produits préfabriqués en béton - Surface et parements de Betonfertigteile - Betonoberflächen -
béton - Éléments d'identification Beschreibungsmerkmale
This Technical Report was approved by CEN on 23 March 2008. It has been drawn up by the Technical Committee CEN/TC 229.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 15739:2008: E
worldwide for CEN national Members.

Contents Page
Foreword .3
Introduction .4
1 Scope .6
2 Terms and definitions .6
2.1 Faces .6
2.2 Finishes .6
2.3 Surface characteristics .9
3 Principle of characterization and identification . 10
3.1 General . 10
3.2 Flatness . 10
3.3 Texture . 10
3.4 Colour . 10
3.5 Identification of the reference . 10
3.6 Definition of level of quality . 11
4 Test methods . 12
4.1 Flatness (deflection) . 12
4.2 Check of appearance . 14
5 Description of units . 16
Annex A (informative) Surface characteristics . 17
Annex B (informative) Example of specifications of requirements applicable to architectural
units . 18
Annex C (informative) Concrete sample surface finish example of acceptance report . 19
Annex D (informative) Reference images to identify the severity of blowholes in concrete
surfaces . 20
Annex E (informative) CIB grey scale . 22
Annex F (informative) Examples of pictures deal with some methods of concrete finishes . 23
Bibliography . 25

Foreword
This document (CEN/TR 15739:2008) has been prepared by Technical Committee CEN/TC 229 “Precast
concrete products”, the secretariat of which is held by AFNOR.
Introduction
The visual perception of concrete finishes is determined by characteristics which can vary to different extents,
i.e. variations which are intentional (more or less). Intended variations imply that one is acquainted with the
material and is able to vary the characteristic within limits set by oneself, without the variations being regarded
as defects.
Finishes depend on manufacturing techniques such as:
Before casting
The finish is determined by the surface of the mould:
 smooth ex-mould finish,
 profiled from the mould,
 profiled/patterned from a lining in the mould,
 cast-on elements,
 use of retarders.
Mould-hardened off-the-form finish
As cast finish obtained through contact with the mould in the case of concrete hardened in the mould. The
face may be smooth or textured.
Dry-cast off-the-form finish
As cast fair-faced finish obtained through contact with the mould in the case of immediate demoulding.
The characteristics of concrete finishes are:
 Texture, from the most elaborated to evenness and, if it is more coarse, unevenness, possibility
developing to a maximum unevenness, which is difficult to stipulate;
 Colour which can be expressed in colour scale;
 Grey tone which can be expressed in grey scales, sometimes with some colour incorporated;
 Pattern, a characteristic, in another type and scale than three above, and which can be formed by
variations in these characteristics.
In contrast to the consciously selected characteristics there can be additional surface aspects of sorts which
are not desired which consequently should be named deviations (i.e. deviations from intentional
characteristics or from the quality level for these characteristics). To these belongs blowholes, lumps, groove
etc.
As a consequence one should separate between characteristics on one side and deviations on the other side
and consider them as different matters, due to the great difference in their nature.
In contrast one should observe that blowholes in certain cases can be intentional, if they are uniformly
distributed over a concrete surface, to lend it a visual “softness”.
For some products, such as architectural components, the required surface appearance could be chosen on
the basis of samples for coordinating the surface character. Before building and delivery, start reference
surfaces are chosen from the sample surface. At the time an order is placed, agreement on the appearance of
the face(s) is formalized by an acceptance report for the reference sample(s) proposed by the manufacturer.
This report also identifies the conventional mean colour chosen from a reference colour chart to be used to
subsequently assess consistency of colour (see Annex C and Annex E).
NOTE 1 Colour scales are not included in this CEN technical report because the paper publication is in black and
white. Each country could establish special colour scales.
NOTE 2 The consistency of concrete appearance is governed by the uniformity of the raw materials from which it is
made or of the pigments used. The fact that the raw materials are of natural mineral origin implies tolerances on the
appearance of the concrete products supplied.
NOTE 3 Because of the time it takes for concrete to cure, the appearance of the reference sample can be assessed
only after a certain minimum time, generally one week after treatment, or longer, depending on the cements used (e.g.
CEM II A and CEM II B) and in all cases at delivery.
NOTE 4 When the colour consistency of several products is inspected at the same time, account should be taken of
any age differences.
1 Scope
This document provides guidelines for the surface appearance of precast concrete products and the methods
for inspecting and assessing the conformity of appearance for use in conjunction with specific product
standards. This document may also be used to describe the appearance of products for which there is no
standard.
If there is a specific standard for a precast concrete product, it takes priority over this document.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1 Faces
2.1.1
seen face
surface intended to be seen when in use
2.1.2
facing layer
layer of concrete on the seen face of a product of different material and/or properties to the main body or
backing layer of a product. Facing layer may be not completely mixed colour concrete (marbling)
NOTE To be distinguished from wipe, i.e. a fine cement mortar or slurry applied to the surface of the product.
2.1.3
arris
part of a product where two faces meet. It can be bevelled, rounded, chamfered, radiussed or splayed
2.1.4
draw
intended angle of the side face from the vertical plane of a product
2.1.5
chamfer
bevelled arris
2.2 Finishes
2.2.1 General
2.2.1.1
unformed surface
surface not in contact with the mould during moulding. This surface may be given complementary treatment
while the concrete is still green to give a more uniform finish. The different treatments possible are defined
below
NOTE In certain special cases the shape of the precast unit may require application of a moulding surface to the
upper face of the unit; this may result in a large number of blowholes which may be attenuated by one of the surface
treatments defined below.
2.2.1.2
screeded
finish obtained by drawing a straightedge, for example, across the surface of the concrete
2.2.1.3
rubbed-off
finish obtained by using a rubbing board , for example, or similar tool
NOTE Cement and sand may be sprinkled on and worked into bleeding concrete or mortar if the quantities are
moderate and the work is regular and carried out with an equally proportioned mix of cement and very fine sand. Use of
cement alone is prohibited.
2.2.1.4
trowelled
finish obtained by using a steel or other kind of trowel, for example
2.2.1.5
semi-polished
finish obtained when the surface of the concrete is semi-polished with a rag or expanded polystyrene, for
example, or brushed with a soft or other kind of brush
2.2.1.6
imprinted
finish obtained by using an indent roller or similar tool to be defined at the time of the order
2.2.2 Worked surfaces
2.2.2.1 Worked in plastic state
2.2.2.1.1
brushed
roughness created by brushing the surface of the fresh mortar with a stiff brush
2.2.2.1.2
water-washed
surface from which the first 2 mm and more of fine mortar is removed by washing
2.2.2.1.3
fine washed
surface from which not more than 2 mm of the first fine mortar is removed by washing
2.2.2.2 Worked in hardened state
2.2.2.2.1
bush hammered
result of scalling the surface of hardened concrete with a bush hammer
2.2.2.2.2
acid-etched
exposed aggregate finish in which the aggregate has been exposed by putting an acid solution on the surface
for a time and washing it off with water
2.2.2.2.3
chemically retarded
exposed aggregate finish (to a greater or lesser extent) in which the concrete surface has been treated with a
retarder and the hardened product has been washed down with water and/or brushed
2.2.2.2.4
splitted
irregularly chipped or hammered face revealing all the constituents of the concrete, including broken coarse
aggregate
NOTE The above techniques require considerable skill in the work procedures, and require extra concrete cover in
the case of reinforced products.
2.2.2.2.5
flamed
exposed aggregate finish in which the top few millimetres of the surface have been flaked off by flame action,
for example
2.2.2.2.6
finely ground
surface ground back with a mechanical grinder, used wet or dry, to partially expose the fine aggregate (sand)
2.2.2.2.7
grinded
description of a surface which is grinded once without abrading. Brush marks and pores can be visible
2.2.2.2.8
coarsely ground
surface ground back to some depth with a mechanical grinder, used wet or dry, to reveal the deep texture of
the concrete and provide rough surface retaining grinding marks
2.2.2.2.9
polished
coarsely ground surface ground several times with increasingly fine grit heads to achieve a uniform finish
without visible marks. Depending on the type of aggregate and the final treatment, the finish may be gloss,
with or without blowholes
2.2.2.2.10
sawed
raspy surface without any more preparation
2.2.2.2.11
abrasive blasted
hardened concrete surface blasted with sand or grit. The grading of the grit, its hardness, and the spray
pressure used enable variation from brush blasting (light abrasion of the surface skin) to heavy blasting that
partially exposes the aggregate
2.2.2.2.12
pressure jetted
hardened concrete surface sprayed with a high-pressure water jet
NOTE The water pressure and adjustment of the jet enable the depth of abrasion and therefore the resulting finish to
be varied.
2.2.2.2.13
shot blasting
erosion of surface by projection of steel shot
2.2.2.2.14
aging
processing with special hammering techniques will give a rustic and antique look
2.2.2.2.15
bossed
on the split surface, aris are broken to give an effect of cut stones
2.2.2.2.16
point tooling
result of scalling the surface of hardened concrete with a pointed graver
2.2.3 Painted or coated surface
2.2.3.1
coated surface
surface faced at delivery in accordance with stipulations made at the time of the order
2.2.3.2
surface to be painted or coated
surface to be painted or coated after delivery
NOTE 1 Since the requisite finish depends on the type and "build" of the paint to be used, these parameters should be
known at the time of the order.
NOTE 2 Any mould release agent on the surface should be compatible with the stipulated paint or coating.
2.3 Surface characteristics
Surface characteristics are defined in Table 1 and Annex A.
Table 1 — Surface characteristics
Characteristics Description
In mass concrete: voids at the surface of the concrete.
For facing concrete: defects consisting of the appearance of bubbles (blisters) or pits (burst
Blowholes
bubbles), generally around 5 mm deep and between a few millimetres and a few centimetres
in diameter (cf. Annex D).
Large crack Crack more than 2 mm wide.
Thin layer of hardened mortar separating from the concrete surface in fragments called
Scaling
‘flakes’.
Corner spalling Spalling at the corner of the concrete unit.
Fine, generally whitish crystalline deposit forming at the concrete surface.
Efflorescence
NOTE When efflorescence occurs it is not deleterious to the performance of the product in use and is
not considered significant.
Spalling Detachment of fragments from a concrete surface.
Network of fine and shallow cracks forming a regular mesh. Appears at the surface of the
Crazing
concrete.
More or less regular linear opening (discontinuity) in the concrete, between
Crack
0,2 mm and 2 mm wide. Any smaller or larger, and it is a micro crack or a large crack.
Crack that does not go through the thickness of the structure. It is widest at the surface and
Surface crack
becomes zero at depth.
Laitence Laitence is a mixture of water and the finer constituents of the concrete.
Swelling Swollen appearance of the concrete due to an increase in volume.
Very tight, more or less regular, most commonly discontinuous linear crack less than 0,2 mm
Micro crack
wide. May extend to form a network.
Honeycombing Defect with lack of fines or mortar between aggregates.
“aggregate
Large aggregate appearance through the concrete surface, creating a network of oval marks
transparency”
which may be darker or lighter than the rest of the surface, depending on the case.
Marbling effect
Surface wear Wear of the concrete due to abrasion or erosion.
Colour variations Differences in concrete colour in the same section of the works.
3 Principle of characterization and identification
3.1 General
The appearance of a concrete surface is defined by three criteria denoted by a letter:
P – Flatness
T – Texture
C – Colour
3.2 Flatness
Flatness is defined by the maximum deflection f = a - b as measured in accordance with 4.1.
max
3.3 Texture
This criterion has three sub-categories to distinguish between:
 general appearance characterized by a mean concentration of blowholes distributed over the entire
surface,
 areas with a concentration (group) of blowholes, and
 localized defects.
3.4 Colour
For each of these criteria, the letter is followed by a number between 0 and 4 corresponding to increasingly
severe requirements.
0 Means that the criterion is not taken into account
1 – 2 – 3 Correspond to codified requirements
4 Corresponds to a requirement specified in the contract.
The characterization of the reference unit, namely a sample or a mock-up should be submitted to the client for
approval before manufacturing. In addition, for surfaces intended to remain visible after the works are
completed, the characterization should be complemented by reference to a colour chart identifying the mean
colour of the reference sample.
NOTE The mean colour is the reference for subsequent assessment of the level of quality (consistency) of the colour
of the products.
When the shape of a product requires that it be made in a multi-p
...