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Über dieses Buch

This book provides practicing engineers with a step by step approach for making durable concrete with optimum use of the local materials available within the various regions of the United States. It further includes actual concrete mixture proportions for high performance concrete for strength and durability under various aggressive environments based on the author’s experience in the field, and support this with illustrative case studies. Examples for concrete mixture proportions, based on the current industry practice and standards, are highlighted to assist engineers in meeting the intended performance requirements (for specific environment conditions) for durable concrete. Covering an important topic for the construction and building materials industries, this book delivers the most up-to-date industry practices and advances in concrete construction from the perspective of a practicing engineer with over 40 year experience.Maximizes practicing engineers’ understanding of best design and construction practices in fabricating, delivery, and installation of concrete, consistent with current knowledge on concrete durabilityDiscusses quality control and testing requirements during design and construction, including mixing, production, and placement of concrete and tolerances for slump and air content
Emphasizes real-world examples of optimal concrete mixtures, suitable for selected service conditions and applications, based on prior successful records of projects within the US
Addresses the role of innovative admixtures in concrete placement in cold weather conditions below 32F and meeting the strength and durability requirements
Serves as a valuable resource for students in graduate programs



Inhaltsverzeichnis

Frontmatter

Chapter 1. Concrete Materials

Abstract
This chapter describes the material constituents for concrete. Materials for concrete include cement, fly ash, ground-granulated blast-furnace slag (GGBFS or slag cement), fine and coarse aggregates, and admixtures. The performance requirements for the concrete materials, which are covered by various industry standards including ASTM and ACI Codes, are summarized. The role of air-entraining and chemical admixtures and their benefit on concrete fresh and hardened properties are discussed. Types of reinforcing steel (carbon, low chrome, or stainless) are also discussed.
Case studies for concrete materials including properties of cement, GGBFS, fly ash, and fine and coarse aggregates used for various exposure and service conditions are included.
Nausherwan Hasan

Chapter 2. Concrete Mixture Design

Abstract
This chapter provides a summary of the concrete mixture proportions design for durability in accordance with Building Codes and Industry Standards set forth for structural and mass concrete durability under various exposure conditions. As defined by ACI 318, for each class of concrete, and exposure condition, the minimum water-to-cementitious material ratios (w/cm) and minimum compressive strength are prescribed. The responsibility of selecting the concrete mixture proportions design rests with the professional engineer, licensed in the state where the construction is carried out.
Trial batches of concrete should be performed, in accordance with ACI 211.1, with adequate lead time to ensure that the test results are available. Emphasis should be given properly to selection of the maximum aggregate size, type of cement, requirement for supplementary cementitious materials including fly ash, GGBFS, silica fume, air entrainment, and the need for chemical admixtures for workability and durability requirements.
Case studies for several recent projects, constructed in the USA and overseas, are discussed to provide guidance for appropriate selection of the concrete materials, mixture proportions consistent with the site, and exposure conditions. Qualification test results for cement, fly ash and GGBFS, silica fume, and aggregates are presented. Mixture proportions for concrete exposed to drying shrinkage, sulfates, and marine environment are included, based on their satisfactory performance history as well as concrete mixture design for placement during cold weather.
Nausherwan Hasan

Chapter 3. Alkali-Silica Reactivity Mitigation

Abstract
This chapter provides an historical review of the alkali-aggregate reactions (AAR) in concrete which reduce service life of concrete, first recognized in 1940, and the development of mitigation measures over the last 80 years. Prior to 1970, it included the use of low-alkali cement, followed by the use of supplementary cementitious materials in the 1980s and chemical admixtures in the 1990s, for mitigating alkali-aggregate reactions. Most of the premature distress is caused by alkali-silica reaction (ASR).
Use of several industry test methods is available to detect ASR. Accelerated ASTM C1260 and C1567 tests, tests developed in the 1980s, are discussed as a prerequisite for ASR determination for a new project. The tests are performed on the aggregate, cement, and fly ash combinations for the projects and define limits for deleterious expansion. Mitigation measures for ASR are discussed, including recommendations for cementitious materials and concrete design mixtures to limit ASR expansion to less than 0.1% at 14 days. Use of lithium nitrate, in combination with fly ash or by itself, including the dosage rates for mitigating ASR in concrete is also discussed.
Case studies for mitigating alkali-silica reaction (ASR) in concrete, involving cast-in-place and precast concrete construction, are included.
Nausherwan Hasan

Chapter 4. Concrete Mixing Placing and Curing

Abstract
This chapter provides guidelines for mixing, transporting, placing, and curing of concrete. It describes the standard equipment and methods, in accordance with established industry standards and practices, to assure that concrete is mixed and placed with uniform consistency and without segregation. The guidelines include surface preparation, consolidation, finishing, and curing requirements.
References to the related industry standards, including ACI, ASTM, and NRMCA, are listed for additional information.
Case studies for several major projects are discussed, which include information on central-mixed batch plant, placement guidelines, tremie placements, and finishing tolerances.
Nausherwan Hasan

Chapter 5. Mass Concrete

Abstract
This chapter describes special requirements, such as materials, mixture proportions, and placing and curing for massive concrete structures.
Four case studies are included for placement of mass concrete for (a) bridge foundations and piers at Paerdegat Basin Bridge, Brooklyn, NY; (b) preassembled powerplant structure at Vidalia, LA; (c) powerhouse lifts around draft tube and scroll cases at Rainbow Powerhouse, Great Falls, MT; and (d) spillway chute at Thomson Forebay Spillway, Carlton, MN.
Thermal control plans and monitoring of concrete temperatures, following placements, are discussed.
Nausherwan Hasan

Chapter 6. Self-Consolidating Concrete (SCC)

Abstract
This chapter describes the special requirements for proportioning, mixing, and placing of self-consolidating concrete (SCC). These requirements are based on ACI 237R and experience from the actual case studies over the years. SCC, as the name suggests, is designed to be flowable so that it can be placed into the forms without the need of consolidation. SCC incorporates chemical admixtures to provide flowability while maintaining its homogeneity. The recent advances in the chemical admixtures, including HRWRA and viscosity-modifying admixtures, allow the concrete to be placed without segregation and eliminates the need of equipment technology.
Several case studies for concrete mixture proportioning. Mixing, and placing SCC, including tremie (underwater) placement is discussed. Testing of trial mixture proportions for SCC, prior to use, is emphasized to firm up placing procedures for optimum results.
Nausherwan Hasan

Chapter 7. Sulfate Attack Mitigation

Abstract
This chapter describes the sulfate attack mechanism on concrete from internal and external sources. While the internal sulfate attack comes from materials in concrete, the external sulfate attack comes from the service environment, as reported by ACI 201.2R-16. (Bates PH, Phillips AJ, Wig RJ. Action of Salts in Alkali Water and Sea Water on Cement. In: Technologic Papers of the Bureau of Standards, vol 12. US Department of Commerce, Washington, DC. 157 pages, 1913).
Two case studies of concrete mixtures, consisting of Type II and V cements with supplementary cementitious materials, to mitigate sulfate attack are discussed. It includes the properties of sulfate-resistant concrete mixtures, including strength and transport properties, and the effects of sulfate attack and degradation on the representative cement paste specimens and recommendations for mitigating sulfate attack.
Nausherwan Hasan

Chapter 8. Drying Shrinkage Mitigation

Abstract
This chapter focuses on understanding the drying shrinkage phenomenon and the mechanism that leads to cracking of concrete. The recent trends to increase the cementitious content of concrete, requiring high performance for bridge decks and highway pavement overlays, are prone to shrinkage and potential cracking. It has become a major maintenance issue for the States Department of Transportation (DOT) in the USA.
Various factors affecting the drying shrinkage are discussed, the most important being the water content, cement content, aggregate content, coarse aggregate size, and curing conditions.
Case studies are included to address mitigation of the drying shrinkage in concrete with shrinkage-reducing admixtures (SRA) in concrete mixture proportions. ASTM test methods for assessing free shrinkage and restrained shrinkage characteristics of concrete to predict potential cracking risks are discussed.
Several case studies are included that describe the use of SRA to mitigate drying shrinkage and cracking. A research study by the Oregon State DOT is also discussed. Based on recent research studies, recommendations to limit drying shrinkage of concrete mixtures in the range of 0.03% to 0.05% at 28 days, optimizing gradation, cement content and incorporating SRA, as well as extending moist curing are also included.
Nausherwan Hasan

Chapter 9. Quality Control During Production

Abstract
This chapter describes the quality assurance and quality control requirements relating to procedures for on-site materials for concrete, including storage, production, testing and record keeping, in accordance with the industry codes and standards. It addresses the responsibilities of the suppliers, submittals, and in-process testing of concrete materials and concrete. Acceptance criteria for concrete strength testing and construction tolerances are discussed.
Case studies from several projects are included with discussion on aggregate tests and concrete production tests concerning the quality control and non-conforming issues during construction.
Nausherwan Hasan

Chapter 10. Concrete Repairs

Abstract
This chapter provides typical procedures and methods for repair of concrete.
Two case histories are included. The first one describes the rehabilitation of a concrete spillway in Michigan, constructed in 1915. The second case study describes the use of controlled low strength material (CLSM) for temporary plugging a leaking cofferdam for repairs to Hebgen Dam intake in Montana.
Nausherwan Hasan

Chapter 11. Durability Requirements for 100-Year Service Life

Abstract
This chapter provides a historical perspective of concrete structures built in the twentieth century, including the challenges faced by the industry and developments that led to rapid advances in the last century. The chapter focuses on a holistic approach to concrete durability that includes quality of materials, mixture proportioning, construction requirements, and quality control of concrete during construction for achieving 100-year service life. A step-by-step approach is provided for achieving the desired durability and service life of concrete.
Nausherwan Hasan

Backmatter

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