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Author: Farhad Reza
Publisher:
ISBN:
Category : Aggregates (Building materials)
Languages : en
Pages : 195
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Book Description
The need to consider sustainability in design dictates that materials should be recycled and reused whenever possible. The Minnesota Department of Transportation (MnDOT) is quite progressive in allowing the use of recycled aggregates in new construction. While the use of recycled concrete aggregate (RCA) in the base course of new pavements is quite common in Minnesota and many other states, it is rarely used in the concrete pavement itself. In fact, Minnesota was one of the few states to build multiple trial projects and has one of the largest number of concrete pavements constructed using the RCA in the concrete itself. The performance of those pavements, most of which are still in service, has never been formally evaluated against similar conventional concrete pavements. This prompted the current research study. Additional objectives were to assess the current state of practice across the nation, conduct experimental investigations using RCA in concrete, assess the sustainability and in particular the economics of using RCA in concrete, and finally to provide some recommendations for guidelines on using RCA in concrete. It has been shown by the authors and other researchers that it is possible to create strong and durable concrete mixtures using RCA as coarse aggregate in volume replacement levels of natural coarse aggregate up to 100%.
Author: Farhad Reza
Publisher:
ISBN:
Category : Aggregates (Building materials)
Languages : en
Pages : 195
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Book Description
The need to consider sustainability in design dictates that materials should be recycled and reused whenever possible. The Minnesota Department of Transportation (MnDOT) is quite progressive in allowing the use of recycled aggregates in new construction. While the use of recycled concrete aggregate (RCA) in the base course of new pavements is quite common in Minnesota and many other states, it is rarely used in the concrete pavement itself. In fact, Minnesota was one of the few states to build multiple trial projects and has one of the largest number of concrete pavements constructed using the RCA in the concrete itself. The performance of those pavements, most of which are still in service, has never been formally evaluated against similar conventional concrete pavements. This prompted the current research study. Additional objectives were to assess the current state of practice across the nation, conduct experimental investigations using RCA in concrete, assess the sustainability and in particular the economics of using RCA in concrete, and finally to provide some recommendations for guidelines on using RCA in concrete. It has been shown by the authors and other researchers that it is possible to create strong and durable concrete mixtures using RCA as coarse aggregate in volume replacement levels of natural coarse aggregate up to 100%.
Author: F. Pacheco-Torgal
Publisher: Elsevier
ISBN: 0857096907
Category : Technology & Engineering
Languages : en
Pages : 671
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Book Description
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
Author: Andreu Gonzàlez Corominas
Publisher:
ISBN:
Category :
Languages : en
Pages : 229
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Book Description
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.
Author: Liam Butler
Publisher:
ISBN:
Category :
Languages : en
Pages : 433
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Book Description
Sustainable resource management and development have been at the forefront of important issues concerning the construction industry for the past several years. Specifically, the use of sustainable building materials and the reuse and recycling of previously used building materials is gaining acceptance and becoming common place in many areas. As one of the most commonly used building materials in the world, concrete, composed of aggregate, sand, cement and water, can be recycled and reused in a variety of applications. Using crushed concrete as fill and subgrade material under roads, sidewalks and foundations has been the most common of these applications. However, research has been ongoing over the past 50 years in many countries including Germany, Canada, Japan, the United States, China, and Australia investigating the use of crushed concrete from demolished old concrete structures to fully or partially replace the virgin aggregate used to produce new concrete for use in building and pavement applications. Producing concrete using recycled concrete aggregates (RCAs) has several advantages, namely, the burden placed on non-renewable aggregate resources may be significantly decreased, the service life and capacity of landfill and waste management facilities can be extended, and the carbon dioxide emissions and traffic congestion associated with the transport of virgin aggregates from remote sites can be reduced. This research is directed at benchmarking typical RCA sources for usage in structural concrete and investigating the inter-relationships between aggregate properties, concrete properties and the bond properties between reinforcing steel and RCA concrete. The experimental program focused on four main areas: aggregate properties testing, development of concrete mixture proportions, concrete fresh and hardened properties testing, and beam-end bond testing. Four coarse aggregate sources were investigated including one virgin or natural aggregate (NA) source, and three RCA sources. Two RCA sources were derived from the crushing of decommissioned building and pavement structures (RCA-1 and RCA-2) while the third source was derived from the crushing of returned ready-mix concrete (RCA-3). A variety of typical and non-typical aggregate tests were performed to provide a basis for correlation with fresh and hardened concrete properties results. A total of 24 concrete mixtures were developed and divided into three separate categories, 1) control, 2) direct replacement, and 3) strength-based mixtures. The control mixtures were proportioned to achieve compressive strengths of 30, 40, 50 and 60MPa with slump values between 75 and 125 mm and served as a basis for comparison with the RCA concrete mixtures. The direct replacement mixtures were developed to investigate the effect that fully replacing (i.e., 100% replacement by volume) virgin coarse aggregate with RCA has on the fresh and hardened properties of the resulting concrete. The strength-based mixtures were developed to investigate the influence of aggregate properties on reinforcement bond in concrete having the same compressive strength. In addition, two separate experimental phases were carried out which had varying compressive strength ranges, different RCA sources, and different suppliers of the same type GU cement. Concrete properties such as slump, compressive strength, splitting tensile strength, modulus of elasticity, Poisson's ratio, linear coefficient of thermal expansion (LCTE), modulus of rupture and fracture energy were all measured. In total, 48 beam-end specimens were tested that incorporated three bonded lengths (125, 375, and 450 mm) and four concrete compressive strengths (30, 40, 50 and 60 MPa). Based on the results of the aggregate testing it was found that concrete incorporating pre-soaked (i.e., fully saturated) RCA as a 100% replacement for natural aggregate had slump values between 22% and 75%, compressive strengths between 81% and 137%, splitting tensile strengths between 78% and 109%, modulus of elasticity values between 81% and 98%, LCTE values in the same range, flexural strengths between 85% and 136%, and fracture energies between 68% and 118%, of the equivalent control (natural aggregate) concrete mixture.
Author: Jorge de Brito
Publisher: Springer Science & Business Media
ISBN: 1447145402
Category : Technology & Engineering
Languages : en
Pages : 453
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Book Description
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.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 208
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Book Description
Concrete is the most commonly used building material in the construction industry, and contributes to 52% of construction and demolition waste in Canada. Recycled concrete aggregate (RCA) is one way to reduce this impact. To evaluate the performance of coarse and granular (fine and coarse) RCA in structural concrete applications, four studies were performed: an environmental assessment, a material testing program, a shear performance study, and a flexural performance study. To determine the environmental benefits of recycled aggregate concrete (RAC), three case studies were investigated using different populations and proximities to city centres. Environmental modelling suggested that RCA replacement could result in energy savings and greenhouse gas emission reductions, especially in remote areas. Tests were performed to determine if the volumetric replacement of up to 30% coarse RCA and 20% granular RCA is suitable for structural concrete applications in Canada. Fresh, hardened, and durability properties were evaluated. All five (5) of the RCA mixes showed equivalent material performance to the control mixes and met the requirements for a structural concrete mix. The five (5) RAC mixes were also used in structural testing. One-way reinforced concrete slab specimens were tested to failure to evaluate the shear and flexural performance of the RAC members. Peak capacities of and crack formation within each member were analyzed to evaluate the performance of RAC compared to conventional concrete. The shear capacity of specimens made from four (4) of the five (5) RAC mixtures was higher or equivalent to the control specimens. Specimens of the concrete mixture containing the highest content of recycled aggregate, 20% volumetric replacement of granular RCA, had shear capacities 14.1% lower, and exhibited cracking at lower loads than the control. The average flexural capacities of all RAC specimens were within 3.7% of the control specimens. Results from this research provide evidence that up to 30% coarse recycled concrete aggregate and 10% granular recycled aggregate may be incorporated into structural concrete mixtures without altering the behaviour of the structure. Concrete containing 20% volumetric replacement of the natural aggregate with granular RCA should be designed with special consideration of the shear performance.
Author:
Publisher:
ISBN:
Category : Aggregates (Building materials)
Languages : en
Pages : 300
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Book Description
This interim report documents the field performance of nine concrete pavement projects that incorporate recycled concrete aggregate (RCA) in the construction of the pavement. Multiple sections were evaluated on many of the nine projects, due to perceived differences in performance levels or variations in pavement design (such as the use of virgin aggregate or the inclusion of dowel bars). All told, a total of 17 sections (of which 12 contain RCA) were subjected to an extensive field testing program, consisting of pavement condition surveys, drainage surveys, falling weight deflectometer (FWD) testing, coring, and serviceability assessments.
Author: Jorge de Brito
Publisher: MDPI
ISBN: 3039211404
Category : Technology & Engineering
Languages : en
Pages : 280
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Book Description
This book is the result of a Special Issue published in Applied Sciences, entitled “New Trends in Recycled Aggregate Concrete". It identifies emerging research areas within the field of recycled aggregate concrete and contributes to the increased use of this eco-efficient material. Its contents are organised in the following sections: Upscaling the use of recycled aggregate concrete in structural design; Large scale applications of recycled aggregate concrete; Long-term behaviour of recycled aggregate concrete; Performance of recycled aggregate concrete in very aggressive environments; Reliability of recycled aggregate concrete structures; Life cycle assessment of recycled aggregate concrete; New applications of recycled aggregate concrete.
Author: Ravindra K Dhir
Publisher: ICE Publishing
ISBN: 9780727764638
Category : Technology & Engineering
Languages : en
Pages : 0
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Book Description
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.
Author: Ravindra K. Dhir OBE
Publisher: Woodhead Publishing
ISBN: 0081009917
Category : Architecture
Languages : en
Pages : 652
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Book Description
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
