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Concrete and cement-based materials must operate in increasingly aggressive aqueous environments, which may be either natural or industrial. These materials may suffer degradation in which ion addition and/or ion exchange reactions occur, leading to a breakdown of the matrix microstructure and consequent weakening. Sometimes this degradation can be extremely rapid and serious such as in acidic environments, while in other cases degradation occurs over long periods. Consequences of material failure are usually severe – adversely affecting the health and well-being of human communities and disturbing ecological balances. There are also large direct costs of maintaining and replacing deteriorated infrastructure and indirect costs from loss of production during maintenance work, which place a great burden on society.

The focus of this book is on addressing issues concerning performance of cement-based materials in aggressive aqueous environments , by way of this State-of-the-Art Report. The book represents the work of many well-known and respected authors who contributed chapters or parts of chapters. Four main themes were addressed: I. Nature and kinetics of degradation and deterioration mechanisms of cement-based materials in aggressive aqueous environments, II. Modelling of deterioration in such environments, III. Test methods to assess performance of cement-based materials in such environments, and which can be used to characterise and rate relative performance and inform long term predictions, IV. Engineering implications and consequences of deterioration in aggressive aqueous environments, and engineering approaches to the problem.

Inhaltsverzeichnis

Frontmatter

Erratum to: Test Methods for Chloride Transport in Concrete

Without Abstract
Qiang Yuan, Manu Santhanam

Mechanisms of Degradation of Cementitious Materials in Aggressive Aqueous Environments

Frontmatter

Chapter 1. General Introduction to Part I

Abstract
Concrete structures are exposed to aggressive aqueous environments in very varied situations, and the range of aggressive species is wide. Among numerous examples, foundations and/or parts of structures in contact with groundwaters, soils or wastewaters may be subject to sulfate attack, and harbour and other maritime facilities are exposed to the action of seawater involving the combined action of magnesium, sulfates and chlorides. Dams, waterpipes and other structures exposed to the action of soft or carbonated waters suffer leaching and/or carbonation. Many agricultural and agrofood facilities (storage silos, animal houses etc.) suffer severe degradation notably linked with organic acids in waste water. The understanding of the mechanisms of degradation of cementitious matrices by these aggressive media is an essential step toward the development of concrete that performs well in these environments and toward the increase of the service life or the safety of the structures and facilities.
Alexandra Bertron

Chapter 2. Sulfate Attack of Concrete

Abstract
Cements have long been known to undergo deterioration in sulfate-rich service environments. Yet the mechanism of attack has not been universally agreed and, arguably of even greater importance, test procedures to measure sulfate attack and specifications for sulfate-resistant formulations are not agreed, or are disputed. We also lack reliable mitigation procedures.
Esperanza Menéndez, Thomas Matschei, Fredrik P. Glasser

Chapter 3. Magnesium Attack of Cementitious Materials in Marine Environments

Abstract
Concrete undergoes numerous chemical reactions with the chemicals in a marine environment. While sodium chloride is the dominant salt in marine waters, there is also a substantial amount of magnesium sulfate. The attack by the Mg ion is particularly dangerous for the system, as it can cause a complete disintegration of the C-S-H in the long term. However, in the presence of a strong chloride environment such as in seawater, there are some differences in the mechanism of magnesium attack as opposed to a typical sulfate attack. This chapter explores the chemistry of magnesium and sulfate attack in a chloride environment.
Manu Santhanam

Chapter 4. Leaching of Cementitious Materials by Pure Water and Strong Acids (HCl and HNO3)

Abstract
Ordinary Portland cement (OPC) is highly alkaline with pH values normally above 12.5, and is easily attacked by pure water and acidic solutions (Chandra 1988; Revertegat et al. 1992; Pavlik 1994a; Faucon et al. 1996, 1998; Israel et al. 1997; Allahverdi and Skvara 2000a; Kamali et al. 2008; Glasser et al. 2008). In fact, all hydrated cement compounds are stable only in solutions with well defined ranges of concentrations for Ca2+ and OH ions. It is well known that in contact with a solution with low mineral content and/or as the pH of the solution decreases, hydrolytic decomposition of the hydrated cement compounds disturbs the equilibrium of the cement matrix, and causes severe degradation of the material, leading to a deterioration in its technical properties (Allahverdi and Skvara 2000a; Pavlik 1994a; Adenot and Buil 1992; Reardon 1990; Biczok 1967; Bertron et al. 2007; Haga et al. 2005a, b; Mainguy et al.2000; Kamali et al. 2008; Jain and Neithalath 2009; Faucon et al. 1996, 1997, 1998). Leaching involves a deterioration of many physical and mechanical properties of cement-based materials such as porosity, elastic modulus, compressive strength, internal friction angle and creep (Burlion et al. 2006; Haga et al. 2005b; Constantinides and Ulm 2004; Bernard et al. 2008; Heukamp et al. 2001; Stora et al. 2009; Sellier et al. 2011).
Josée Duchesne, Alexandra Bertron

Chapter 5. Ammonium Nitrate Attack on Cementitious Materials

Abstract
Of the factors that can quickly degrade concrete, ammonium salts are among the most aggressive (Lea 1965; Biczok 1972). Ammonium nitrate, a very commonly used fertilizer, is at the origin of severe degradation of concrete structures, especially in factories manufacturing these fertilizers or in storage silos.
Gilles Escadeillas

Chapter 6. Attack of Cementitious Materials by Organic Acids in Agricultural and Agrofood Effluents

Abstract
Agricultural and agrofood industries such as the breeding, dairy or sugar industries produce large quantities of effluents. As these waste waters may be important sources of pollution of the environment, notably of natural water resources (Müller and Heil 1998; Martinez and Le Bozec 2000), they cannot be released into the environment without treatment. They must be collected, stored and eventually treated to comply with chemical, physical, and microbial standards before being released into public streams.
Alexandra Bertron, Josée Duchesne

Modeling Degradation of Cementitious Materials in Aggressive Aqueous Environments

Frontmatter

Chapter 7. Modeling Degradation of Cementitious Materials in Aggressive Aqueous Environments

Abstract
The vast majority of the world’s concrete infrastructure was built around the middle of the twentieth century, and for the most part is now approaching an age of half a century or more. In many cases, the structures are showing signs of degradation mechanisms such as corrosion of the steel reinforcement, alkali-silica reaction (ASR), and freeze-thaw.
Patrick Le Bescop, Barbara Lothenbach, Eric Samson, Kenneth A. Snyder

Methods for Testing Concrete Degradation in Aggressive Aqueous Environments

Frontmatter

Chapter 8. General Considerations

Abstract
In recent decades, numerous concrete structures have shown severe durability problems. Degradation mechanisms such as alkali silica reaction, chloride penetration, carbonation, acid attack, biogenic sulfuric acid attack, etc. have necessitated the complete renewal of some structures. Apart from the inconvenience and even occasional loss of life caused by the failure of structures, these degradation problems have caused huge financial losses. These include not only the cost of repair and restoration of structures, but also the economic losses caused for example by traffic problems during the temporary closure of bridges, roads and tunnels. It is therefore important to tackle these problems by formulating the most appropriate concrete compositions and by taking protective measures.
Nele De Belie

Chapter 9. Tests for Leaching and Degradation in Soft or Carbonated Waters

Abstract
Leaching can be defined in a general manner as the extraction of certain materials from a solid by a liquid. In a porous solid, leaching is a combined diffusion-dissolution/precipitation process where the concentration gradients between the pore solution and the pure water cause diffusion of the extracted materials from the pore solution to the surrounding water. The reduction in concentration of the targeted species in the pore solution forces the dissolution of more material.
Marta Castellote

Chapter 10. Test Methods for Resistance of Concrete to Sulfate Attack – A Critical Review

Abstract
Sulfate attack comprises a series of chemical reactions between sulfate ions and the components of hardened concrete. As these reactions may lead to cracking, spalling or strength loss of concrete structures, appropriate test methods are needed to determine the resistance of concrete under sulfate exposure. Accelerated test methods are most suitable since sulfate attack is typically a long term process. The current ASTM C1012 (2004) test method accelerates the attack mechanism by using a solution with a high sulfate concentration in which mortar specimens are immersed. The SVA procedure (see Table 10.1 for more detail) uses smaller specimens to obtain results earlier (Mielich and Öttl 2004). In the Wittekindt method not only smaller specimens are used but also the w/c-ratio is increased (Wittekindt 1960). However, these tests still require several months. Test methods such as ASTM C452 (2006) and the Chatelier-Anstett test use a mixture of cement and gypsum. Since in this case the sulfate source is located internally, no more time is needed for sulfate ingress. With these test methods results are obtained after 2 weeks, but the attack mechanism no longer represents field conditions in a realistic way.
Kim Van Tittelboom, Nele De Belie, R. Doug Hooton

Chapter 11. Testing for Degradation by Inorganic Acids

Abstract
Acid testing of concrete specimens is not simple. Questions to be considered are: the type of acid to be used; the representativeness of the concrete mixtures tested; the nature of the measurements to characterise degradation; and how the results are to be applied to practical design and prediction of service life. It was mentioned in
Mark G. Alexander, Nele De Belie

Chapter 12. Bacteriogenic Sulfuric Acid Attack of Cementitious Materials in Sewage Systems

Abstract
Well functioning sewage networks are critical to public health. Increasing urbanisation puts rising demands on existing networks and creates a need for new networks, especially in developing countries. Sewage networks represent a very aggressive environment for cementitious materials. At the same time their relative inaccessibility poses challenges for maintenance and repair. The main cause of degradation is the corrosion of concrete due to the in-situ production of sulfuric acid by bacteria. In this chapter, we discuss the mechanisms behind this so-called bacteriogenic corrosion and the state of the art for determination of the relative resistance of different concrete types to this form of degradation. The reader is also referred to Monteny et al. (2000) for a more extensive review on the subject.
Karen Scrivener, Nele De Belie

Chapter 13. Test Methods for Chloride Transport in Concrete

Abstract
Chlorides per se are not generally thought of as being damaging to concrete. However, chlorides can alter the products of cement hydration, and also cause other forms of concrete deterioration. For these reasons, this chapter is included here.
Qiang Yuan, Manu Santhanam

Chapter 14. Test Methods for Magnesium Attack

Abstract
In chemical attack research, the role of the cation is often not addressed adequately, particularly when the cation is magnesium, Mg2+. Conventional tests that determine the influence of aggressive chemicals such as sulfates or chlorides do not address the deterioration brought about by the presence of Mg.
Manu Santhanam

Chapter 15. Methods for Testing Cementitious Materials Exposed to Organic Acids

Abstract
Concrete in agricultural and agro-industrial settings suffers severe degradation, notably linked with attack by waste waters (De Belie et al. 1997a, 2000a, b; O’Donnell et al. 1995a, b). Waste waters such as liquid manure, silage juices, whey, molasses and distillery residues contain organic acids that attack the concrete. Concrete is the most widely used material for the construction of structures intended for the production, collection, storage and treatment of such effluents as it complies with several requirements: it is economical, watertight, ensures good thermal inertia and respects the health standards imposed in agro-food industries.
Alexandra Bertron

Cementitious Materials Performance in Aggressive Aqueous Environments – Engineering Perspectives

Frontmatter

Chapter 16. Cementitious Materials Performance in Aggressive Aqueous Environments – Engineering Perspectives

Abstract
Concrete forms an indispensable element of structures throughout the world. It is essential that the production of concrete or cement-based materials meets predetermined expectations, which may be set out in the form of specifications or codes, the key considerations for which can be summarized as follows:
  • the intended design life of the structure or its constituent elements
  • the environmental exposure conditions
  • the essential requirements of serviceability
  • the fixation of measurable criteria to define serviceability failure
  • the planned maintenance requirements
  • the risk levels and safety factors.
Anjan Chatterjee, Alaster Goyns

Backmatter

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