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Proceedings pro035 : International RILEM Workshop on Internal Sulfate Attack and Delayed Ettringite Formation


Title: International RILEM Workshop on Internal Sulfate Attack and Delayed Ettringite Formation
Edited by K. Scrivener and J. Skalny
ISBN: 2-912143-44-6
e-ISBN: 2912143802
Pages: 316
Publication date: 2004

Two forms of internal sulfate attack (ISA) have long been known:

* ISA due to contamination of the aggregates by sulfates
* ISA due to over sulfation of the cement

This workshop dealt with a third form of ISA, which has only come to attention relatively recently. This form of ISA has been observed in concretes (and mortars) which have experienced elevated temperatures during curing, either through the external application of heat as in steam curing, or from internal temperature rise due to the heat evolved during hydration. This form of ISA is widely known as Delayed Ettringite Formation or DEF. Despite its general use, this term can be misleading as it has long been known that in concretes exposed to moisture ettringite will recrystallised harmlessly into pore, void and previously existing cracks. This phenomenon is more usually referred to as secondary ettringite formation. Furthermore, it has also been observed that in concretes which have been heat cured ettringite may form at late ages (delayed formation) without any detrimental effect on the concrete.

In particular the workshop aimed to establish the extent to which the following questions could be answered:

* Does the DEF form of ISA occur only in concretes which have experienced temperatures in excess of some threshold temperature (around 70°C). Can it also occur in concretes which have been maintained at ambient temperatures?
* What parameters in the cement and concrete influence the likelihood of expansion after exposure to elevated temperatures during curing?
* Can high sulfate contents originating in the clinker (rather than added during grinding) induce this form of ISA even in the absence of elevated temperatures?
* How prevalent is this form of ISA in the field? How may it be identified in the field concrete given the confusion of other forms of degradation - frost damage or alkali silica reaction, coupled with the formation of secondary ettringite in the cracks formed by these deterioration processes?
* Can the formation of ettringite in pre-existing cracks lead to the lengthening and/or widening of these cracks? Can the deposition of ettringite in air-voids jeopardise the resistance of the concrete to frost damage?

The workshop was organised with sessions designed to address these key questions.
A combination of keynote papers and extensive discussion, also reported in these proceedings, is believed to give a complete picture of the current state of the art relating to this form of Internal Sulfate Attack.


Contents


Preface
Author(s): K. Scrivener
Pages: XI - XIII

Notes on Terminology
Author(s): RILEM
Pages: XVI - XVI

Theme 1: Sulfates in Portland cement clinker and cement


Sulfates in Portland clinker and cement
Author(s): H. F. W. Taylor
Pages: 3 - 17

Distribution of sulfates in Portland cement clinker
Author(s): D. Herfort
Pages: 18 - 27

Sulfates in high SO3/alkali clinker. Their dissolution kinetics and their influence on concrete workability and durability
Author(s): V. Michaud-Poupardin, R. W. Suderman
Pages: 28 - 40

Theme 2: Basics of ettringite stability


The stability of ettringite
Author(s): F. P. Glasser
Pages: 43 - 64

On the chemistry of delayed ettringite formation
Author(s): H. Y. Ghorab
Pages: 65 - 81

Theme 3: Case studies of DEF


Field cases of delayed ettringite formation
Author(s): M. D. A. Thomas, T. Ramlochan
Pages: 85 - 97

Delayed ettringite formation in massive concrete structures: an account of some studies of degraded bridges
Author(s): L. Divet, A. Pavoine
Pages: 98 - 126

Delayed ettringite formation in massive concrete structures: an account of some studies of degraded bridges
Author(s): E. Menéndez
Pages: 127 - 136

Theme 4: Mechanisms of expansion


Factors affecting crystallization pressure
Author(s): G. W. Scherer
Pages: 139 - 154

The role of C-S-H and temperature in delayed ettringite formation
Author(s): R. Barbarulo, H. Peycelon, S. Prené
Pages: 155 - 166

Role of microstructural characterisation in understanding the mechanism of expansion due to delayed ettringite formation
Author(s): C. Famy, K. L. Scrivener, A; R. Brough
Pages: 167 - 172

Ettringite needed in gaps?
Author(s): V. Johansen, B. Osbæck
Pages: 173 - 177

Delayed ettringite formation - a current assessment
Author(s): S. Diamond
Pages: 178 - 194

Theme 5: Parameters affecting expansion after exposure to elevated temperatures


Effects of cement parameters on expansion associated with DEF
Author(s): S. Kelham
Pages: 197 - 211

The influence of sulfate content in clinker or cement and curing temperature on DEF-related expansion of concrete
Author(s): M. Collepardi, J. J. Ogoumagh Olagot
Pages: 212 - 228

Can addition of limestone eliminate the expansion of the mortars due to DEF ?
Author(s): W. Kurdowski, S. Duszak
Pages: 229 - 235

Theme 6: Cracks and Airvoids


Ettringite in air voids
Author(s): E. Samson, J. Marchand, B. Zuber, J. P. Skalny
Pages: 239 - 258

Role of cracks in delayed ettringite formation
Author(s): K. Scrivener, A. Guidoum, V. Mathier
Pages: 259 - 262

Theme 7: What have we learned from this workshop


Internal sulfate attack - points of agreement and disagreement
Author(s): J. Skalny
Pages: 265 - 276

Summary of discussions during workshop


Summary of discussions during workshop
Author(s): RILEM
Pages: 277 - 296