22 Damage to concrete structures
concept, enabling the evaluation and attestation of concrete with nonstandard cement types and/or puzzolanic additions. This standard, NBN
B15-100, considers two important terms: ‘general suitability’ and ‘specific
suitability’. General suitability refers to the fact that a constituent material
can be successfully used within concrete. Materials having a CE-mark are
considered to be generally suitable. For non-certified materials, the general
suitability first has to be evaluated experimentally (e.g. composition, alkali
content, chloride content, mechanical properties, stability, heat of hydration, setting, loss on ignition, residue, sulphate content).
The most important part of the standard NBN B15-100 deals with specific suitability. This refers to the suitability of a specific mix for a specific
field of application and exposure conditions. The specific suitability has to
be checked by means of Initial Type Testing (ITT) on real concrete mixes.
The evaluation of the durability is based on comparative laboratory tests,
comparing the non-traditional concrete composition with standard solutions accepted by EN 206-1. For more details on this method, reference is
made to De Schutter (2009).
1.5.4 Durability indicators
Although the ECPC concept provides an excellent opportunity to evaluate the durability of concrete based on new binder types, the main discussion point is the definition of well-accepted reference concrete for the
considered exposure classes. This is inherent to the fact that the ECPC
concept is a comparative method, comparing durability performance
with accepted deemed-to-satisfy solutions. A more sound evaluation of
durability performance could be based on absolute performance criteria.
Although we are still far from defining absolute durability performance
criteria for completed concrete structures or concrete elements, considerable progress is being made following the approach of so-called durability indicators (Baroghel-Bouny et al. 2009), combined with fundamental
models.
A list of general durability indicators, which are relevant to many degradation processes, can be defined including calcium hydroxide content,
water accessible porosity, chloride ion diffusion coefficient, and gas or water
permeability. In order to study the durability performance with regard to
some specific degradation mechanisms, some specific durability indicators
can be considered, e.g. relevant to freeze-thaw damage or alkali-silica reaction. Some complementary parameters can also be needed as input data
for the fundamental prediction models, e.g. the chloride concentration at
the concrete surface. Based on the durability indicators, durability classes
can be proposed, ranging from very low to very high potential durability
as illustrated in Figure 1.13. More detailed examples can be found in literature (Baroghel-Bouny et al. 2009).
concept, enabling the evaluation and attestation of concrete with nonstandard cement types and/or puzzolanic additions. This standard, NBN
B15-100, considers two important terms: ‘general suitability’ and ‘specific
suitability’. General suitability refers to the fact that a constituent material
can be successfully used within concrete. Materials having a CE-mark are
considered to be generally suitable. For non-certified materials, the general
suitability first has to be evaluated experimentally (e.g. composition, alkali
content, chloride content, mechanical properties, stability, heat of hydration, setting, loss on ignition, residue, sulphate content).
The most important part of the standard NBN B15-100 deals with specific suitability. This refers to the suitability of a specific mix for a specific
field of application and exposure conditions. The specific suitability has to
be checked by means of Initial Type Testing (ITT) on real concrete mixes.
The evaluation of the durability is based on comparative laboratory tests,
comparing the non-traditional concrete composition with standard solutions accepted by EN 206-1. For more details on this method, reference is
made to De Schutter (2009).
1.5.4 Durability indicators
Although the ECPC concept provides an excellent opportunity to evaluate the durability of concrete based on new binder types, the main discussion point is the definition of well-accepted reference concrete for the
considered exposure classes. This is inherent to the fact that the ECPC
concept is a comparative method, comparing durability performance
with accepted deemed-to-satisfy solutions. A more sound evaluation of
durability performance could be based on absolute performance criteria.
Although we are still far from defining absolute durability performance
criteria for completed concrete structures or concrete elements, considerable progress is being made following the approach of so-called durability indicators (Baroghel-Bouny et al. 2009), combined with fundamental
models.
A list of general durability indicators, which are relevant to many degradation processes, can be defined including calcium hydroxide content,
water accessible porosity, chloride ion diffusion coefficient, and gas or water
permeability. In order to study the durability performance with regard to
some specific degradation mechanisms, some specific durability indicators
can be considered, e.g. relevant to freeze-thaw damage or alkali-silica reaction. Some complementary parameters can also be needed as input data
for the fundamental prediction models, e.g. the chloride concentration at
the concrete surface. Based on the durability indicators, durability classes
can be proposed, ranging from very low to very high potential durability
as illustrated in Figure 1.13. More detailed examples can be found in literature (Baroghel-Bouny et al. 2009).