Civil Engineering Reference
In-Depth Information
8
Influence of supplementary cementitious
materials (SCMs) on concrete durability
M. C Y R, University of Toulouse, France
DOI
: 10.1533/9780857098993.2.153
Abstract
:
This chapter presents the effects of supplementary cementitious
materials (SCMs) on properties affecting the durability of concrete (porosity,
permeability), and on the major factors affecting concrete durability (alkali-
silica reaction, delayed ettringite formation, sulphate attacks, acid attacks,
frost resistance, abrasion, carbonation and chloride ingress). General trends
and specific effects of ground-granulated blast-furnace slag, fly ash, silica
fume and metakaolin, when used as cement replacement, are reported and
discussed.
Key words
: pozzolans, mineral admixtures, supplementary cementitious
materials, ground-granulated blast-furnace slag, fly ash, silica fume,
metakaolin, porosity, permeability, alkali-silica reaction, delayed ettringite
formation, sulphate attacks, acid attacks, frost resistance, abrasion,
carbonation, chloride ingress, corrosion.
8.1 Introduction
For many engineers, concrete materials are specified principally on the
basis of their compressive strengths at 28 days. Current standards, such as
EN 206-1, correct this point of view by taking the durability of concretes
into account and classifying them according to exposure classes related to
environmental actions (corrosion induced by carbonation or by chlorides,
freeze/thaw attacks and chemical attacks).
According to ACI Committee 201's Guide to Durable Concrete (ACI,
2008), the 'durability of hydraulic-cement concrete is defined as its ability
to resist weathering action, chemical attack, abrasion, or any other process
of deterioration. Durable concrete will retain its original form, quality, and
serviceability when exposed to its environment.' Supplementary cementitious
materials (SCMs) greatly affect the durability of concrete and an extremely
large number of research papers have been published, increasing the difficulty
of generalizing the effect of a given mineral admixture on a durability
property. Nevertheless, this chapter, which is in three main sections, tries
to present general trends concerning the effects of SCMs on the principal
topics regarding the durability of concrete (Fig. 8.1):
∑ the major properties governing durability, i.e. porosity and per-
meability;
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