CEN/TR 17310:2019

SLOVENSKI STANDARD
01-maj-2019
Karbonatizacija in absorpcija CO2 v beton
Carbonation and CO2 uptake in concrete
Karbonatisierung und CO2-Aufnahme von Beton
Carbonatation et absorption du CO2 dans le béton
Ta slovenski standard je istoveten z: CEN/TR 17310:2019
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.

CEN/TR 17310
TECHNICAL REPORT
RAPPORT TECHNIQUE
January 2019
TECHNISCHER BERICHT
ICS 91.100.30
English Version
Carbonation and CO uptake in concrete
Carbonatation et absorption du CO dans le béton Karbonatisierung und CO -Aufnahme von Beton
2 2
This Technical Report was approved by CEN on 30 December 2018. It has been drawn up by the Technical Committee CEN/TC
104.
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 NORMALISATIO N

EUROPÄISCHES KOMITEE FÜR NORMUN G

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 17310:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Carbonation, the uptake of carbon dioxide . 5
4.1 Compounds, chemistry and notation . 5
4.2 Carbonation . 6
4.2.1 Carbonation reactions . 6
4.2.2 Process of carbonation . 7
4.2.3 Degree of carbonation . 8
4.2.4 Effect of carbonation on cement paste structure. 10
4.2.5 Carbonation rate . 11
4.2.6 Carbonation rate controlling factors . 11
4.2.7 Carbonation rate of concrete with blended cements or with additions. 15
4.3 CO binding capacity in concrete, Degree of carbonation . 16
4.3.1 General . 16
4.3.2 Theoretical binding capacity of Portland cement . 17
4.3.3 Normal binding capacity of Portland cement . 17
4.3.4 Normal binding capacity of blended cements. 18
4.4 Carbonation in different environments . 19
4.4.1 General . 19
4.4.2 Dry indoor concrete . 19
4.4.3 Concrete exposed to rain. . 20
4.4.4 Concrete sheltered from rain . 20
4.4.5 Wet or submerged concrete . 20
4.4.6 Buried concrete . 21
5 Practical experiences of CO uptake in concrete life stages . 21
5.1 CO uptake during product stage (module A) . 21
5.2 CO uptake during use stage (module B) . 22
5.3 CO uptake during end of life stage . 29
5.3.1 CO uptake during end of life stage – demolition, crushing and waste handling
(module C1-C3) . 29
5.3.2 CO uptake during end of life stage – landfill (module C4) . 32
5.4 CO uptake beyond the system boundary (module D) . 32
6 Figures for "direct estimation” of CO uptake in whole structures during use stage . 33
6.1 General . 33
6.1.1 General . 33
6.1.2 CO uptake for a portal frame bridge . 34
6.1.3 CO uptake for a residential building . 35
6.2 Average CO uptake for construction types, strength classes and exposure . 36
7 Additional information . 37
7.1 CO uptake in the long term, beyond the service life of the structure . 37
7.2 CO uptake of crushed concrete in new applications . 38
8 Society perspective – Carbonation and CO uptake in mortar . 38
9 National calculation models and methods . 39
9.1 General . 39
9.2 Calculation of Carbonation of concrete in use phase (Swiss approach) . 39
9.2.1 General . 39
9.2.2 Water/CaO . 39
9.2.3 CO concentration, relative humidity and CO buffer capacity . 39
2 2
9.2.4 A simple approach of assessing the CO uptake of concrete components . 40
9.2.5 Ratio of CO uptake/CO emission as a function of thickness of concrete element . 43
2 2
Bibliography . 45

European foreword
This document (CEN/TR 17310:2019) has been prepared by Technical Committee CEN/TC 104
“Concrete and related products”, the secretariat of which is held by SN.
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.
1 Scope
This document provides detailed guidance on the carbonation and carbon dioxide (CO ) uptake in
concrete. This guidance is complementary to that provided in EN 16757, Product Category Rules for
concrete and concrete elements, Annex BB.
Typical CO uptake values for a range of structures exposed to various environmental conditions are
presented. These values can be incorporated into EPDs for the whole life cycle for either: a functional
unit, one tonne or one m of concrete, without necessarily having any detailed knowledge of the
structure to be built.
In the rest of the document, the data will be given per m .
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
4 Carbonation, the uptake of carbon dioxide
4.1 Compounds, chemistry and notation
4.1.1 Carbon dioxide: Chemically expressed as CO and present in the atmosphere as a gas. When
CO is dissolved in water, H O, it may form carbonic acid, H CO , where this may release carbonate,
2 2 2 3
2− −
CO , and bicarbonate, HCO ions.
3 3
4.1.2 Calcium hydroxide: Chemically expressed as Ca(OH) and often called Portlandite. It is a
product of the hydration of Portland cement and is always present in concrete. For simplicity, cement
chemists often denote calcium hydroxide as CH. Calcium hydroxide is not very soluble in water but is
+ −
does dissolve to the ions Ca and 2OH . The presence of calcium hydroxide in concrete is largely
responsible for maintaining its alkaline environment, which is at a pH around 12,5. Around 25 % of
hardened hydrated cement is Ca(OH) .
4.1.3 Calcium oxide: Chemically expressed as CaO. Portland cement clinker contains 61 % to 67 %
CaO by oxide analysis, and where typically the assumed value is 65 %. Nearly all the calcium oxide in
Portland cement is not present as calcium oxide but as part of more complicated compounds such as
di-calcium silicates, tri-calcium silicates, tri-calcium aluminate and tetra-calcium alumina ferrite.
Fortunately using the oxide analysis figure of 65 % CaO is sufficient for the calculation of potential
carbonation without going into the more complex chemistry.
4.1.4 Calcium silicate hydrates, and other hydration products: When Portland cement reacts with
water, that is when it hydrates, it forms calcium hydroxide and a larger proportion of complex
hydration products where the bulk of these are made up of calcium and silica. The hydration products,
or gel as described by concrete technologists, are called calcium-silica-hydrates, often simplified to CSH.
For a typical composition of hardened hydrated cement it is assumed 50 % is CSH, around 25 % is
calcium hydroxide, 10% calcium monosulfoaluminate-AFm, 10 % ettringite-AFt leaving 5 % undefined.
4.1.5 Calcium carbonate: Chemically expressed as CaCO , normally present in concrete as calcite.
4.2 Carbonation
4.2.1 Carbonation reactions
The reaction between carbon dioxide and calcium hydroxide, to form calcium carbonate, CaCO , and
water, H O, is called carbonation. The reaction can be expressed as a formula:
CO + Ca OH → CaCO + H O
(1)
( )
2 3 2
This formula makes it appear that the reaction is simply carbon dioxide as a gas reacting with calcium
hydroxide as a solid, but in reality the kinetics of the reaction are more complicated in that moisture
2− −
must be present for the intermediate stages, where carbonate, CO , bicarbonate, HCO , calcium
3 3
+ −
Ca and hydroxide 2OH ions interact.
In addition to carbonation of calcium hydroxide directly, the calcium-silicate-hydrates also carbonate.
This is a complex reaction where CSH is made up of short silica chains bound together by calcium ions,
2+ −
Ca , and hydroxide, OH , ions with the water more or less firmly bound. The makeup of CSH can be
characterized by its calcium to silica ratio, expressed as either CaO/SiO or Ca/Si, where the
2+
un-carbonated value is around 1,85. As carbonation lowers Ca content of the pore solution this is
2+
compensated by the release of Ca from the CSH [6], and its Ca/Si ratio drops to around 0,85. As the
Ca/Si ratio falls below 1, and the pH is reduces to around 10, the CSH transforms into a silica gel
...