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Über dieses Buch

This book examines state-of-the-art techniques for using recycled materials for structural concrete production, and explores the use of concrete with metallurgical slag, rheology of fresh recycled concrete, and life-cycle analysis of building materials. It reviews recent codes, guidelines and practices for using recycled materials in structural concrete application, and presents research recently carried out by the authors.
Focusing on techniques that limit the environmental impacts of the concrete industry, the text explores the use of recycled components in the place of virgin aggregates and ordinary binders. Chapters focus on topics including processing procedures, mixture proportioning, mechanical properties, durability and structural applications. Providing a valuable resource to engineering postgraduates and researchers, this book is also intended for civil engineers, geologists, and concrete engineers.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

This book aims to provide some insights about the use of recycled materials for producing structural concrete, particularly about the use of recycled aggregates coming from construction and demolition waste and metallurgical slag. Workability, rheology, mechanical and durability properties are here discussed, collecting some experimental results from literature. Sustainability issue is also explored, through the review of the main environmental indicators, which can be applied for evaluating the impacts of construction materials.
Carlo Pellegrino, Flora Faleschini

Chapter 2. Recycled Aggregates for Concrete Production: State-of-the-Art

In the last decades, problems linked to industrial material landfill disposal has become more and more relevant to society, with cost increases for environment and municipalities. Waste reutilization is attractive to reduce economical costs and potential pollution problems, and preserve natural raw resources. In this context, the promotion of recycling in concrete industry may represent a valid route for sustainable development, preventing natural resources consumption, valorizing recycled materials, and avoiding the landfill of huge amount of materials. Nowadays, there are, among others, two significant possibilities to reduce natural aggregates exploitation: the use of recycled concrete from construction and demolition waste (C&DWs) and the use of slag from metallurgical industrial production. Additionally the use of supplementary cementing materials (SCMs) can reduce the great environmental emissions due to cement use. In this chapter, a review about the most commonly used recycled aggregates is given, i.e. recycled aggregates from C&DW and from metallurgical slag, with a special focus about the available codes and normative which regulate their use in structural concrete.
Carlo Pellegrino, Flora Faleschini

Chapter 3. Workability and Rheology of Fresh Recycled Aggregate Concrete

The use of recycled aggregates concrete (RAC) with coarse recycled concrete aggregates (CRCA) has been widely studied in literature. A number of works investigated both mechanical and durability-related properties of these concretes; however, fresh properties of RAC have not been extensively analyzed yet. Limited studies were focused on the influence of some recycled aggregate properties on slump, which is the most frequently used measure to evaluate workability. Since this measure is a single-value and it is often operator-sensitive, a more quantitative estimate can be derived in terms of fundamental physical quantities, such as plastic viscosity and yield stress. The higher heterogeneity in terms of experimental slump measure occurs indeed when recycled aggregate concrete is tested. In this chapter, a review of the existing experimental methods for the evaluation of fresh concrete workability is given. Additionally, the behavior of fresh concrete is explored, aiming to understand which physical phenomena govern the macroscopic rheological behavior, under some specific conditions, e.g. in terms of mix composition, casting conditions, etc. Some experimental results about fresh recycled concretes workability and rheology, collected from literature, are also discussed.
Carlo Pellegrino, Flora Faleschini

Chapter 4. Electric Arc Furnace Slag Concrete

The aim of this section is to comprehensively investigate the possibility of substituting natural aggregates with Black/Oxidizing Electric Arc Furnace (EAF) slag, at high replacement ratios, to produce structural concrete. The properties of the slag are described in detail, in terms of chemical composition, mineralogy, microstructure and physical characteristics. A review of the main physical and mechanical properties of concrete containing EAF slag is reported, analyzing the effect of the substitution on compressive and tensile strength and on elastic modulus, both for producing ordinary strength and high strength concretes. Durability-related properties in aggressive environments are also discussed, paying attention on freezing/thawing, drying/wetting conditions, and chlorides-contaminated exposure. Results showed that high substitution ratios of coarse natural aggregates are possible without decreasing mechanical properties of concrete, and on the contrary, slag use enhances concrete strength. Conversely, replacement of fine natural aggregates with fine slag seems feasible at lower substitution ratios only. Presence of calcium and magnesium oxides in the slag does not seem to represent a limit for the durability of concrete, due to their stabilization in crystalline lattice.
Carlo Pellegrino, Flora Faleschini

Chapter 5. Sustainability of Recycled Concretes Through Life Cycle Assessment

A significant number of green concrete have been recently designed to meet the growing request of reducing construction industry impacts, saving raw materials and preventing industrial by-products’ discard. Between these, recycled aggregates coming from construction and demolition waste (CDW) and Black/Oxidizing Electric Arc Furnace (EAF) slag have been founded to be suitable for structural concrete applications, when used as replacement of natural coarse aggregates. However it is necessary to solve the arising question about how those recycled materials effectively improve the sustainability of concrete industry. A quantitative estimate of the environmental impacts’ related to the production of those concretes can be performed using several environmental indicators. In this section a review of the available environmental tools, useful to assess concrete impacts, is reported. Particularly Life Cycle Analysis (LCA) and abiotic depletion indicator can be satisfactorily applied to quantify the emission reduction due to the use of recycled aggregates instead of natural gravel in structural concrete. The procedure described in this section can be applied to determine the impacts of other recycled aggregates concretes, practically estimating the environmental footprint of the material.
Carlo Pellegrino, Flora Faleschini

Chapter 6. Experimental Database of EAF Slag Use in Concrete

An experimental database about the properties of electric arc furnace slag is gathered. Data have been collected in literature from more than 40 research works, where the slag has been used in many applications, e.g. in mortar, concrete and for applications in bituminous mixtures. Physical properties, chemical composition, leaching and expansion potential are here included. The properties of the products have been also collected, including mix proportions and performances. The database represents an important-state-of-the-art about the use of EAF slag in civil engineering applications, with a particular attention paid to the uses in structural concrete.
Carlo Pellegrino, Flora Faleschini
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