Alkali-Aggregate Reaction in Concrete

A World Review

Ian Sims, Alan Poole, Ian Sims, Alan Poole, Ian Sims, Alan B. Poole

• Publisher: CRC Press
• Year: 2017
• Print ISBN: 9780367573331
• eBook ISBN: 9781317484417
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Chemistry
• Index: Chemistry

Alkali-Aggregate Reaction in Concrete: A World Review is unique in providing authoritative and up to date expert information on the causes and effects of Alkali-Aggregate Reaction (AAR) in concrete structures worldwide. In 1992 a first edition entitled The Alkali-Silica Reaction in Concrete, edited by Professor Narayan Swamy, was published in a first attempt to cover this concrete problem from a global perspective, but the coverage was incomplete. This completely new edition offers a fully updated and more universal coverage of the world situation concerning AAR and includes a wealth of new evidence and research information that has accumulated in the intervening years.

Although there are various textbooks offering readers sections that deal with AAR deterioration and damage to concrete, no other single book brings together the views of recognised international experts in the field, and the wealth of scattered research information that is available. It provides a 'state of the art' review and deals authoritatively with the mechanisms of AAR, its diagnosis and how to treat concrete affected by AAR. It is illustrated by numerous actual examples from around the world, and comprises specialist contributions provided by senior engineers and scientists from many parts of the world.

The book is divided into two distinct but complementary parts. The first five chapters deal with the most recent findings concerning the mechanisms involved in the reaction, methods concerning its diagnosis, testing and evaluation, together with an appraisal of current methods used in its avoidance and in the remediation of affected concrete structures. The second part is divided into eleven chapters covering each region of the world in turn. These chapters have been written by experts with specialist knowledge of AAR in the countries involved and include an authoritative appraisal of the problem and its solution as it affects concrete structures in the region.

Such an authoritative compilation of information on AAR has not been attempted previously on this scale and this work is therefore an essential source for practising and research civil engineers, consultant engineers and materials scientists, as well as aggregate and cement producers, designers and concrete suppliers, especially regarding projects outside their own region.

Chapter 1

Introduction, Chemistry and Mechanisms

Alan B. Poole

1.1 Background

Several varieties of concrete were used as construction materials by the Romans. The development of concrete based on hydraulic cement similar to that used at the present time dates from the 19^th Century. Since then a great number of technological improvements have occurred, extending the varieties of cements and hence concretes available today. In one form or another, concrete has become an essential and ubiquitous constructional material across the modern world.

Along with the technological refinements, a basic scientific understanding of the nature of this material has been developed, including the realisation that certain problems can and do occur, some of which can lead to its premature deterioration and failure.

One such problem arises from an injudicious selection of aggregate and cement types when designing and mixing the concrete. Although the concrete may initially meet all the required specifications of strength development and quality, after several years of service, it has been found that a few concretes begin to expand and crack, necessitating expensive remedial work or replacement. The particular problem involved is referred to as Alkali-Aggregate Reaction (AAR); and constitutes the subject of the present volume. This book updates and replaces the first edition entitled ‘The Alkali-Silica Reaction in Concrete’ (Editor: R.N. Swamy, 1992); and offers a greatly extended world coverage of AAR, including a global review of the problem and some of the possible solutions currently available.

AAR in concrete was first observed and identified in North America during the late 1930s and the first comprehensive scientific investigations describing the reaction and its effects were published by Stanton in December, 1940. Stanton investigated a number of occurrences of expansion and cracking leading to failures in concrete pavements in California, and found that the problem developed only when certain types of mineral components were present in the aggregates, and only when cement alkalis exceeded some minimum threshold percentage concentration. The reaction between the aggregate and the alkali gave rise to the name “alkali-aggregate reaction”. His findings encompassed a great deal of detailed information regarding the nature and practical significance of the reactions taking place, and included early versions of test methods that later became standards, and of methods of preventing or at least mitigating the results of the reactions. In a recent appreciation, Thomas (2011); suggested that the impact of Stanton’s findings could not be overstated. Prior to his publication, aggregate was considered to be an inert filler, but afterwards it was realized that some aggregates were not suitable for use in concrete without taking special precautionary measures. Of course, Stanton’s findings that cement alkalis could influence the durability of concrete caused great concern for the cement manufacturing companies and perhaps the most disturbing implication of Stanton’s study was that concrete could “fail… even if it is exposed to only normal curing and weathering conditions”.

Since this early work a tremendous volume of research into causes, effects, avoidance and possible solutions to the problem of AAR in concrete has been undertaken. This work has been driven in part by the major costs involved in making good the damage AAR can cause, but also by the world-wide extent of the problem, AAR being found to occur in so many countries (see Figure 1.1);. Despite the fact that the actual occurrence of damaging AAR in concrete structures is relatively rare and seemingly spasmodic, the repair or replacement of affected structures involves a major expense for their owners.

Figure 1.1 A world map indicating countries and areas or regions where cases of AAR in concrete structures have been identified, investigated, reported or where avoidance specifications are in place.

Most of the research into this problem has taken place since the Second World War, giving rise to an extensive technical literature numbering several thousand research papers and technical reports. An important source of information concerning this work has been in the form of the proceedings of a series of International Conferences on AAR (‘ICAARs’);. The first of these was held in Copenhagen in 1974 and the 15^th was held in Sao Paolo, Brazil in 2016. In addition, numerous national specifications and guidance documents for avoiding AAR have been published and will be referred to in later chapters of his book.

This second edition offers an up-to-date general overview of research into AAR in concrete. The coverage includes methods of diagnosis and testing (Chapter 2);, a discussion of ‘alkali-carbonate reaction’ (Chapter 3); and conclusions concerning the prevention, mitigation and management of affected concrete (Chapters 4 and 5);. The later chapters (6 – 16); then review AAR affected concrete and how the problem is dealt with in the different countries and regions of the world. The world map shown in Figure 1.1 illustrates the countries where AAR has been investigated or reported. Text-Box 1.1 lists the countries and regions where AAR has been investigated. It gives an indication of potentially reactive aggregate types and an indication of the reported cases and types of structures affected in the different regions.

Text-Box 1.1 A summary listing of countries and regions detailed in later chapters where examples of AAR in structures have been reported, or where potential for AAR has been investigated.

Country/Region	Examples of potentially Reactive aggregate types	Some Reported Case of AAR	Comments and References	Chapter
Europe				6,7 & 8
Austria	Sedimentary sands and gravels	Roads, pavements dams	Quartzite and gneisses identified as reactive	8
Belgium	Quaternary sands and gravels, argillaceous limestone, quartz diorite, dacite	Bridges, bridge decks, hydro structures	150 structures affected Denmars (2012);	8
Cyprus	Crushed opaline siliceous limestone, river and beach gravels	Marine structures buildings	Poole (1975); Siliceous reef limestone aggregate with high water absorption (3.3);	8
Czech Republic	Granodiorite, quartzite, phyllite, acid volcanics, quartz-feldspar tuffs, siliceous limestone	Highway structures, bridges, airport pavements, dams, tunnels	Cryptocrystalline quartz identified as reactive in a range of rock types	8
Denmark	Opaline flint, calcareous flint, microporous flints	Swimming pools Bridges, roads	Cements low alkali, external sources may contribute alkali. Marked pessimum behaviour. Rapid reaction. Nielson et al. (2004);	7
France	Siliceous limestone, quartzite, Rhône gravels, meta-granite and gneiss in Alpine region	Dams, bridges, retaining walls	ASR in over 400 structures, 10 demolished. Most in N. France and Brittany. Some cases complicated by DEF and sulfate attack	8
Finland	Pre-Cambrian gneiss, cataclasites, mylonites	Bridges, housing, industrial buildings	70+ structures identified. Confused with freeze-thaw. Air entrainment & ggbs in common use. Local cement high-alkali. Pyy et al. (2012);	7
Germany	Opaline sandstone, flint, greywacke, siliceous limestone	Bridges, highway pavements, precast slabs	First identified early 1950s, typically rapid reaction time	8
Hungary	Sands and gravels, carbonates and volcanics	None reported	Only andesite potentially reactive. Common use of ggbs cementreplacement	8
Iceland	Sea dredged basalt, andesite, rhyolite, aggregates containing secondary opal	Domestic housing, hydraulic structures, pavements	Early cements are high alkali. Fly ash, pozzalans & silica fume in common use. Wigum et al. (2009/10);	7
Italy	River sands and gravels and carbonates containing chert, jasper, chalcedony	Residential and industrial buildings, pavements	Barisone, G. & Restivo, G. (1992b);	8
Netherlands	River sands and gravels	Bridges, viaducts, tunnel linings	Sea dredged gravel non-reactive common use of pfa. Broekmans (2002);	8
Norway	Sandstones, greywacke, claystone, mylonite, cataclasite, acid volcanics	Bridges, hydraulic structues, precast units, foundations, pipes, dams	Typically slowly reacting, use of fly ash in cement to mitigate ASR. Wigum et al. (2004);	7
Poland	Sands and gravels containing opal and chalcedony, sandstone, siliceous limestone and dolomite	Viaducts, buildings, precast elements	Large producer of aggregates, but variable quality. Góralczyk (2001);	8
Portugal	Granitoid types, basalts	Dams, bridges	Mostly slow reaction ASR (Silva et al., 2016); Dolomite + crypto crystalline silica are potentiallyreactive.	8
Republic of Ireland	Chert and greywacke	None reported	Some high alkali cements	6
Slovenia	River sands and gravels, opaline breccia	Concrete columns	ASR in floor due to crushed glass contamination	8
Spain	Quartzite, granodiorite, granite, monzonite, schist, slate	Hydraulic structures, dams, bridges	Quartzite and monzonite with micro and crypto crystalline quartz fast reacting others slow	8
Sweden	Gravels with porous flint, limestone with ...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Editors and Authors
• Acknowledgments
• 1. Introduction, Chemistry and Mechanisms
• 2. Assessment, Testing and Specification
• 3. So-Called Alkali-Carbonate Reaction (ACR)
• 4. Prevention of Alkali-Silica Reaction
• 5. Diagnosis, Appraisal, Repair and Management
• 6. United Kingdom and Ireland
• 7. Nordic Europe
• 8. Mainland Europe, Turkey and Cyprus
• 9. Russian Federation
• 10. North America (USA and Canada)
• 11. South and Central America
• 12. Southern and Central Africa
• 13. Japan, China and South-East Asia
• 14. Australia and New Zealand
• 15. Indian Sub-Continent
• 16. Middle East & North Africa
• Index