Khatib Sustainability of Construction Materials

1. Auflage 2009
ISBN: 978-1-84569-584-2
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 900 Seiten

Reihe: Woodhead Publishing Series in Civil and Structural Engineering

Until recently, much of the development of building materials has predominantly focused on producing cheaper, stronger and more durable construction materials. More recently attention has been given to the environmental issues in manufacturing, using, disposing and recycling of construction materials. Sustainability of construction materials brings together a wealth of recent research on the subject.The first part of the book gives a comprehensive and detailed analysis of the sustainability of the following building materials: aggregates; timber, wood and bamboo; vegetable fibres; masonry; cement, concrete and cement replacement materials; metals and alloys; glass; and engineered wood products. A final group of chapters cover the use of waste tyre rubber in civil engineering works, the durability of sustainable construction materials and nanotechnologies for sustainable construction.With its distinguished editor and international team of contributors, Sustainability of construction materials is a standard reference for anyone involved in the construction and civil engineering industries with an interest in the highly important topic of sustainability. - Provides a comprehensive and detailed analysis of the sustainability of a variety of construction materials ranging from wood and bamboo to cement and concrete - Assesses the durability of sustainable construction materials including the utilisation of waste tyre rubber and vegetable fibres - Collates a wealth of recent research including relevant case studies as well as an investigation into future trends

Autoren/Hrsg.

Khatib, Jamal

Leseproben

1 Sustainability of aggregates in construction
W. Langer    United States Geological Survey, USA Abstract
Aggregate consists of manufactured crushed stone and sand created by crushing bedrock, and naturally occurring unconsolidated sand and gravel. The infrastructure created using aggregate is a major contributor to our current standard of living. Maintaining our lifestyle, passing that lifestyle on to our progeny, and supporting others to achieve developed nation status, will require huge amounts of aggregate. This chapter describes the aggregate industry and sustainable aggregate resource management, including the complex environmental, societal, and social issues associated with the exploration, mining, processing, transportation, and recycling of aggregate resources, and the reclamation of mined-out aggregate deposits. Key words aggregate gravel crushed stone sustainability 1.1 Introduction
Natural aggregate consists of manufactured crushed stone and sand created by crushing bedrock, or naturally occurring unconsolidated sand and gravel. It is a major component of asphalt and concrete, and is required in streets, highways, railroads, bridges, buildings, sidewalks, sewers, power plants, and dams – just about every part of the built environment. Aggregate is the world’s number-one non-fuel mineral commodity in terms of both volume and value (Fig. 1.1). During 1998, worldwide, about 20 billion tonnes of aggregate worth about 120 billion Euros were produced (Wellmer and Becker-Platen, 2002). Worldwide demand is estimated to be rising by 4.7% annually (Bleischwitz and Bahn-Walkowiak, 2006). 1.1 Graph showing the value of worldwide non-fuel mineral production during 1998. Data from Wellmer and Becker-Platen (2002). This chapter describes the natural aggregate industry and methods to sustain aggregate resources. Sections 1.2–1.6 describe aggregates and the aggregate industry including: Section 1.2 – production, transport, reclamation, potential environmental impacts, and methods to manage those impacts; Section 1.3 – substitutes; Section 1.4 – recycling; Section 1.5 – performance in use; and Section 1.6 – waste products from aggregates. Sections 1.7 to 1.9 describe sustainable aggregate resource management (SARM), including: Section 1.7 – the environmental, economic, and social aspects of SARM; Section 1.8 – the status of SARM; and Section 1.9 – general approaches to SARM. Section 1.10 contains four case studies. Section 1.11 discusses the future of SARM and Section 1.12 describes sources of further information. 1.2 Production of aggregate
If aggregate is to be produced from new sources, certain conditions must be met. • Sand, gravel, or rock must exist in sufficient quantity and quality to make mining worthwhile and it must be accessible to transportation systems and to markets. • The property must be of sufficient size to locate a pit or quarry and processing equipment, and be owned by a person or people willing to sell or lease it at a reasonable price. • The deposit must physically be able to be mined without causing unacceptable impacts to the environment. • The extraction and processing site must qualify for all necessary permits. • The approving officials and the public must be convinced that the operation can take place without adversely affecting the environment or their lifestyle. In other words, the operator must be able to obtain a ‘social license’ to mine. • The operation must be profitable considering all costs including: exploration, acquisition, permitting, operation, environmental controls, compliance with regulations, transport to market, and reclamation. The production of aggregate involves extraction and processing of the raw material into a useable product, transport of that commodity to the point of use, and the reclamation of mined-out pits or quarries. The following is a general description of the production of natural aggregate. More detailed discussions can be found in the sources of further information listed in Section 1.12.1. 1.2.1 Extraction and processing
Sand and gravel deposits commonly are excavated from pits utilizing conventional earth-moving equipment. Mining crushed stone generally requires drilling and blasting of solid bedrock (also referred to as ledge or ledge-rock), which breaks the rock into rubble of a size suitable for crushing. Crushed stone and sand and gravel commonly are obtained from dry pits or quarries, but in some settings may be mined from water-filled excavations using dredges mounted on barges, or with draglines. Sand and gravel or rock rubble at the mine face are transported by truck or conveyor to a processing plant. The material is crushed, passed over a screening device, and sorted according to size (Fig. 1.2). The crushing, screening, and sorting process is repeated until the proper mix of particle sizes is reached. Sand and gravel may or may not be crushed, depending on the size of the largest gravel particles and the desired product. Depending on the specifications of the final product, the processed material may be washed to remove dust. Sand may be screened from the mixture and processed separately. After screening, sorting, and washing (if necessary), the sand and different size gravel/rock particles are moved by conveyors to separate stockpiles where they are stored until sold and shipped. 1.2 Typical crushed stone processing plant. 1.2.2 Transportation
Most aggregate is sold in bulk. Upon sale, aggregate is loaded on trucks, railcars, barges, or freighters for transport to a destination. Aggregate is a high-bulk, low-value commodity, and transportation can add substantially to the cost at the point of use. For example, the cost of transportation of aggregates in the European Union is about 13% of the total cost of the aggregate (Bleischwitz and Bahn-Walkowiak, 2006). The method of transport depends on a number of factors including volumes of material, distance to the point of use, delivery schedules, and access to rail or water transport systems. Trucks are by far the most flexible and most common means of transporting aggregate. They can be loaded and unloaded at many locations using a variety of techniques and can accommodate most delivery schedules. Rail and barge are much less flexible because they utilize fixed route systems following strict schedules and require considerable investment capital in terms of loading facilities, off-loading facilities, and distribution yards. Trains and barges achieve economy by moving large volumes of aggregate long distances on regular schedules (Hayes, 1991). 1.2.3 Reclamation
Reclamation may be implemented following four reclamation strategies: progressive, segmental, interim, or post-mining (Norman and Lingley, 1992). Progressive reclamation immediately follows the removal of aggregate, but may be impractical for operations that must blend mined material from different parts of the pit or quarry. Segmental reclamation follows the removal of minerals in designated sections of the mine, is cost efficient, establishes final slopes as part of the mining operation, and works best in homogeneous deposits. Interim reclamation temporarily stabilizes disturbed areas with fast-growing grasses or legumes, and at a later time implements the final reclamation plan. Post-mining reclamation does not begin until the entire mine has been exhausted, which may lead to deterioration of stockpiled soils, a longer revegetation time frame, and high bonding liability (Norman and Lingley, 1992). The following examples (from Arbogast et al. (2000), unless otherwise noted) illustrate the many different ways that sites can be reclaimed. Reclamation can produce economic benefits by reusing pits or quarries as residential property, industrial and commercial properties, office parks, landfills, golf courses, recreational areas, and botanical gardens. Water-filled pits or quarries are especially well suited for lake-form residential properties, reconstructed wetlands, and water storage reservoirs. These types of reclamation often occur in or near urban centers with large populations. For example, beginning in 1904, Buchart Gardens in British Columbia, Canada, reclaimed 50 acres of an exhausted limestone quarry to create a premier botanical garden (Fig. 1.3). 1.3 Buchart Gardens, a reclaimed limestone quarry. Notice the cement kiln stack in the background. Some reclamation uses an artistic approach where the site is celebrated as a work of beauty and unique experiences. For example, Robert Smithson, a pioneer in the earthworks-as-art movement, created a circular jetty and canal entitled ‘Broken Circle’ from a sand pit and body of water in the Netherlands. The symmetrical landform is about 40 m in diameter and evokes images of the dikes and polders that are the backbone of the Dutch landscape. Another form of art can be illustrated by the festival...