Evaluation of the Effects of Recycled Aggregates on the Properties of High Performance Concrete

Evaluation of the Effects of Recycled Aggregates on the Properties of High Performance Concrete
Author: Andreu Gonzàlez Corominas
Publisher:
Total Pages: 229
Release: 2016
Genre:
ISBN:

In recent decades, the use of High Performance Concrete (HPC) has grown vastly, being used in multiple applications with high requirements. However, the use of recycled aggregates (RA) has been mostly limited to conventional concrete. Many studies have defined limiting properties of RA, replacement ratios of natural aggregates and particular techniques to achieve suitable conventional concrete containing RA. Nonetheless, very few studies have been focused on the use of RA in the production of HPC. This study examines the behaviour of High Performance Recycled Aggregate Concrete (HPRAC) in physical, mechanical, durability and structural properties according to the RA content and its quality. RA were sourced from Construction and Demolition Waste of several categories: Recycled Concrete Aggregate (RCA) obtained from 40, 60 and 100 MPa concretes, Ceramic Waste Aggregates (CWA) and Recycled Mixed Aggregates (RMA). In the first experimental phase, the limiting replacement ratios of RA were established in order to achieve comparable HPRAC to the reference HPC with a design strength of 100 MPa. The physical, mechanical and durability properties were studied for concretes containing 20, 50 and 100% of coarse RCA and RMA, and 15 and 30% of fine CWA. According to the mechanical properties, 100% of coarse RCA can be used, as long as RA is sourced from a 60 MPa minimum-strength concrete waste. Nevertheless, durability behaviour was more influenced by the use of RA and replacement ratios of RCA could only be maintained on those obtained from parent concretes with the same quality as the new HPC. Moreover, significant reductions of the RA quality (RCA sourced from 40MPa - strength concretes or RMA) only permitted 20% replacement ratios. On the other hand, the concretes containing fine CWA (up to 30%) reached higher performances than those from conventional HPC. On the second experimental phase, fly ash was used in replacement of 30% of Portland cement in order to enhance the RCA performance. Keeping in mind prestressed concrete as potential application which requires high early-age strength, the concrete mixtures were also subjected to an initial steam curing cycle. The natural aggregates could be completely replaced by RCA sourced from the same quality HPC, producing improved mechanical properties and pore structures. It was determined that when using lower quality aggregates, the use of steam curing was mandatory to fulfil the standard requirements for prestressed concrete. The steam curing had negative effects on the long-term mechanical properties, however the steam-cured HPRAC had greater improvements on the pore structure and the mechanical properties than conventional HPC. The third experimental phase assesses the role of RCA in internal curing whose effect is significant in HPC. The effects of RCA were investigated in the plastic, autogenous and drying shrinkage of HPC, being the second of special interest in concretes with low water-cement ratio. The results revealed that the plastic and drying shrinkage became higher as the quality of the RCA decreased and the replacement ratio increased. However, a reduction in the autogenous shrinkage was proved to be possible by the use of a high content of lower quality RCA, since they acted as internal curing agents. The suitable behaviour of the HPRAC mixtures containing 50 and 100% of RCA sourced from 100 MPa-strength concretes enabled the production of prestressed concrete sleepers. The structural properties of HPRAC were tested on the conventional HPC and on both HPRAC sleepers. The prestressed concrete sleepers were subjected to static and dynamic load tests at rail-seat and centre sections. The structural requirements for prestressed concrete sleepers were extensively verified by sleepers made with HPRAC. Regardless of the replacement ratio, the HPRAC sleepers' results barely differed from those of conventional HPC sleepers.

Sustainable Construction Materials

Sustainable Construction Materials
Author: Ravindra K. Dhir OBE
Publisher: Woodhead Publishing
Total Pages: 652
Release: 2019-01-05
Genre: Architecture
ISBN: 0081009917

Sustainable Construction Materials: Recycled Aggregate focuses on the massive systematic need that is necessary to encourage the uptake of recycled and secondary materials (RSM) in the construction industry. This book is the fifth and the last of the series on sustainable construction materials and like the previous four, it is also different to the norm. Its uniqueness lies in using the newly developed, Analytical Systemisation Method, in building the data-matrix sourced from 1413 publications, contributed by 2213 authors from 965 institutions in 67 countries, from 1977 to 2018, on the subject of recycled aggregate as a construction material, and systematically analysing, evaluating and modelling this information for use of the material as an aggregate concrete and mortar, geotechnics and road pavement applications. Environmental issues, case studies and standards are also discussed. The work establishes what is already known and can be used to further progress the use of sustainable construction materials. It can also help to avoid repetitive research and save valuable resources. The book is structured in an incisive and easy to digest manner and is particularly suited for researchers, academics, design engineers, specifiers, contractors, and government bodies dealing with construction works. Provides an exhaustive and comprehensively organized list of globally-based published literature spanning 5000 references Offers an analysis, evaluation, repackaging and modeling of existing knowledge that encourages more responsible use of waste materials Provides a wealth of knowledge for use in many sectors relating to the construction profession, including academia, research, practice and adoption of RSM

Recycled Aggregate in Concrete

Recycled Aggregate in Concrete
Author: Jorge de Brito
Publisher: Springer Science & Business Media
Total Pages: 453
Release: 2012-11-28
Genre: Technology & Engineering
ISBN: 1447145402

Concrete is the most used man-made material in the world since its invention. The widespread use of this material has led to continuous developments such as ultra-high strength concrete and self-compacting concrete. Recycled Aggregate in Concrete: Use of Industrial, Construction and Demolition Waste focuses on the recent development which the use of various types of recycled waste materials as aggregate in the production of various types of concrete. By drawing together information and data from various fields and sources, Recycled Aggregate in Concrete: Use of Industrial, Construction and Demolition Waste provides full coverage of this subject. Divided into two parts, a compilation of varied literature data related to the use of various types of industrial waste as aggregates in concrete is followed by a discussion of the use of construction and demolition waste as aggregate in concrete. The properties of the aggregates and their effect on various concrete properties are presented, and the quantitative procedure to estimate the properties of concrete containing construction and demolition waste as aggregates is explained. Current codes and practices developed in various countries to use construction and demolition waste as aggregates in concrete and issues related to the sustainability of cement and concrete production are also discussed. The comprehensive information presented in Recycled Aggregate in Concrete: Use of Industrial, Construction and Demolition Waste will be helpful to graduate students, researchers and concrete technologists. The collected data will also be an essential reference for practicing engineers who face problems concerning the use of these materials in concrete production.

Recycled Aggregates

Recycled Aggregates
Author: Ravindra K Dhir
Publisher: ICE Publishing
Total Pages: 0
Release: 2019-09-09
Genre: Technology & Engineering
ISBN: 9780727764638

The book is an ideal source of information on the subject and would be a suitable addition to any library as a resource for researchers seeking to develop an overview of the research on this topic.

Waste Materials Used in Concrete Manufacturing

Waste Materials Used in Concrete Manufacturing
Author: Satish Chandra
Publisher: Elsevier
Total Pages: 673
Release: 1996-12-31
Genre: Science
ISBN: 0815519516

The environmental aspects involved in the production and use of cement, concrete and other building materials are of growing importance. CO2 emissions are 0.8-1.3 ton/ton of cement production in dry process. SO2 emission is also very high, but is dependent upon the type of fuel used. Energy consumption is also very high at 100-150 KWT/ton of cement produced. It is costly to erect new cement plants. Substitution of waste materials will conserve dwindling resources, and will avoid the environmental and ecological damages caused by quarrying and exploitation of the raw materials for making cement. To some extent, it will help to solve the problem otherwise encountered in disposing of the wastes. Partial replacement of clinker or portland cement by slag, fly ash, silica fume and natural rock minerals illustrates these aspects. Partial replacement by natural materials that require little or no processing, such as pozzolans, calcined clays, etc., saves energy and decreases emission of gases. The output of waste materials suitable as cement replacement (slags, fly ashes, silica fumes, rice husk ash, etc.) is more than double that of cement production. These waste materials can partly be used, or processed, to produce materials suitable as aggregates or fillers in concrete. These can also be used as clinker raw materials, or processed into cementing systems. New grinding and mixing technology will make the use of these secondary materials simpler. Developments in chemical admixtures: superplasticizers, air entraining agents, etc., help in controlling production techniques and, in achieving the desired properties in concrete. Use of waste products is not only a partial solution to environmental and ecological problems; it significantly improves the microstructure, and consequently the durability properties of concrete, which are difficult to achieve by the use of pure portland cement. The aim is not only to make the cements and concrete less expensive, but to provide a blend of tailored properties of waste materials and portland cements suitable for specified purpose. This requires a better understanding of chemistry, and materials science. There is an increasing demand for better understanding of material properties, as well as better control of the microstructure developing in the construction material, to increase durability. The combination of different binders and modifiers to produce cheaper and more durable building materials will solve to some extent the ecological and environmental problems.

Aggregates in Concrete

Aggregates in Concrete
Author: Mark Alexander
Publisher: CRC Press
Total Pages: 448
Release: 2010-02-25
Genre: Technology & Engineering
ISBN: 0203963695

Bringing together in one volume the latest research and information, this book provides a detailed guide to the selection and use of aggregates in concrete. After an introduction defining the purpose and role of aggregates in concrete, the authors present an overview of aggregate sources and production techniques, followed by a detailed study of their physical, mechanical and chemical properties. This knowledge is then applied to the use of aggregates in both plastic and hardened concretes, and in the overall mix design. Special aggregates and their applications are discussed in detail, as are the current main specifications, standards and tests.

Concrete Recycling

Concrete Recycling
Author: Francois de Larrard
Publisher: CRC Press
Total Pages: 859
Release: 2019-03-04
Genre: Technology & Engineering
ISBN: 1351052802

The concrete industry consumes thirty billion tons of aggregate annually, almost all from non-renewable natural sources. Demolition produces a growing amount of materials which are legally usable and readily available. If not used locally they must be transported and landfilled. Also, demolition generally takes place close to new construction sites: recycling promotes shorter transportation distances, a must for improving the overall environmental footprint of the construction world. This book encompasses all aspects of this current trend: How recycled aggregates are obtained and their properties. Improving their quality through phase selection or separation. Incorporating concrete from demolition into the cement production process and the properties of the product obtained. What are the properties of concrete incorporating recycled concrete aggregates at various replacement levels, throughout the lifecycle of the material, from the fresh state to the long-term, including durability and fire. How recycled concrete can be optimised for various uses. How this new structural material can be managed in reinforced concrete construction. Solid experience from a series of experimental sites, and drawing on the Recybéton project, which lasted more than 5 years and gathered about 50 partners (from both academia and industry). Specific issues in recycled concrete quality control. National practices in the most advanced countries, and the main national and European standards. Achieving a sustainable process.

Handbook of Recycled Concrete and Demolition Waste

Handbook of Recycled Concrete and Demolition Waste
Author: F. Pacheco-Torgal
Publisher: Elsevier
Total Pages: 671
Release: 2013-09-30
Genre: Technology & Engineering
ISBN: 0857096907

The civil engineering sector accounts for a significant percentage of global material and energy consumption and is a major contributor of waste material. The ability to recycle and reuse concrete and demolition waste is critical to reducing environmental impacts in meeting national, regional and global environmental targets. Handbook of recycled concrete and demolition waste summarises key recent research in achieving these goals. Part one considers techniques for managing construction and demolition waste, including waste management plans, ways of estimating levels of waste, the types and optimal location of waste recycling plants and the economics of managing construction and demolition waste. Part two reviews key steps in handling construction and demolition waste. It begins with a comparison between conventional demolition and construction techniques before going on to discuss the preparation, refinement and quality control of concrete aggregates produced from waste. It concludes by assessing the mechanical properties, strength and durability of concrete made using recycled aggregates. Part three includes examples of the use of recycled aggregates in applications such as roads, pavements, high-performance concrete and alkali-activated or geopolymer cements. Finally, the book discusses environmental and safety issues such as the removal of gypsum, asbestos and alkali-silica reaction (ASR) concrete, as well as life-cycle analysis of concrete with recycled aggregates. Handbook of recycled concrete and demolition waste is a standard reference for all those involved in the civil engineering sector, as well as academic researchers in the field. Summarises key recent research in recycling and reusing concrete and demolition waste to reduce environmental impacts and meet national, regional and global environmental targets Considers techniques for managing construction and demolition waste, including waste management plans, ways of estimating levels of waste, the types and optimal location of waste recycling plants Reviews key steps in handling construction and demolition waste