As manufactured sand often is produced dry, with high fines content, and a “long” grading, segregation is common when storing and transporting manufactured sand. As a consequence it is necessary to define procedures for sampling, handling and testing for quality control purposes to ensure that the “right” material is being tested.
crushers are significant in the final outcome when manufacturing sand, in particular the crusher type, their setting and the number of crushing stages. Other processing equipment includes feeders and silos, screens, conveyor belts and – in some cases – washing equipment.
Finally, it is important to know from the start the intended end-use of the material since the optimal properties vary according to end-use and this may often be controlled during the processing period.
Fines
The definition of particle size of fines is diverse. According to the EN-product standard EN 126204 for concrete aggregates, fines are all material less than 63 μm. ASTM standards have a similar limit of 75 μm. For practical concrete purposes in Norway it is quite common that all material less than or 125 μm are referred to as fines.
While fines is a part of the sand aggregate, either the lower part of the grading curve, or sometimes also as a contamination, the well defined, added fine size fraction is commonly referred to as filler. Commercially fillers are supplied mostly from limestone , sometimes from quartz. But even the bottom size of the actual aggregate can be produced as well defined filler.
Prospects of the Future – Environmental Challenges
As it has been mentioned, it is recognised, both nationally and on a global scale, an increased miss balance between the need for aggregates in the society and the availability of traditionally suitable geologic sources. We can estimate that close to 80% of the sand and gravel ever taken out of the nature, has been consumed in our generation.
According to prof. Roger Flanagan, UK (lecture given at NTNU Trondheim in October 2008), the availability of materials will be one of the important global market drivers in the years to come. As a consequence there is a strong need for developing and implementing technology that can enable the use of alternative resources, reduce the need for transport and present zero waste concepts for the aggregate and concrete industry.
In Norway it is already the situation, as natural aggregate resources near urban centres terminate, that the transport distances increase significantly.
According to information from the Geological Survey of Norway, NGU, (2008)5 it is clear that some of the most important natural sand and gravel resources, e.g. in south-western Norway, and areas serving the Oslo region, will be finished within 10-30 years. It has been emphasised by NGU that there is a clear need to develop a strategy how to preserve important concrete aggregate recourses, and what to do in regions already scarce in natural aggregates.
In a forecast for the aggregate market in US, presented by Vulcan Materials Company (2007)6, it is claimed that the demand for aggregates will continue to grow in the future. The demand will be driven primarily by population growth and the associated requirements for residential and non-residential construction, and the need to upgrade and/or replace aging infrastructure of all types. It is emphasised that it will become more difficult to site and open new quarries, particularly in proximity to high-growth areas. It is also predicted that the need to ship aggregates over greater distances will increase the number of distribution facilities in metropolitan areas. Other issues of consideration in their forecast are:
• The need for aggregate producers to meet tighter specifications, will results in more unusable materials being produced.
• Recycled concrete will continue to play an important role in urban areas; however, recycled materials will remain a small part of the total aggregate supply.
• Community relations issues in the future will remain important and will likely place additional restraints on locating and operating aggregate facilities.
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Some of the factors affecting quality of manufactured sand
As manufactured sand often is produced dry, with high fines content, and a “long” grading, segregation is common when storing and transporting manufactured sand. As a consequence it is necessary to define procedures for sampling, handling and testing for quality control purposes to ensure that the “right” material is being tested.
crushers are significant in the final outcome when manufacturing sand, in particular the crusher type, their setting and the number of crushing stages. Other processing equipment includes feeders and silos, screens, conveyor belts and – in some cases – washing equipment.
Finally, it is important to know from the start the intended end-use of the material since the optimal properties vary according to end-use and this may often be controlled during the processing period.
Fines
The definition of particle size of fines is diverse. According to the EN-product standard EN 126204 for concrete aggregates, fines are all material less than 63 μm. ASTM standards have a similar limit of 75 μm. For practical concrete purposes in Norway it is quite common that all material less than or 125 μm are referred to as fines.
While fines is a part of the sand aggregate, either the lower part of the grading curve, or sometimes also as a contamination, the well defined, added fine size fraction is commonly referred to as filler. Commercially fillers are supplied mostly from limestone , sometimes from quartz. But even the bottom size of the actual aggregate can be produced as well defined filler.
Prospects of the Future – Environmental Challenges
As it has been mentioned, it is recognised, both nationally and on a global scale, an increased miss balance between the need for aggregates in the society and the availability of traditionally suitable geologic sources. We can estimate that close to 80% of the sand and gravel ever taken out of the nature, has been consumed in our generation.
According to prof. Roger Flanagan, UK (lecture given at NTNU Trondheim in October 2008), the availability of materials will be one of the important global market drivers in the years to come. As a consequence there is a strong need for developing and implementing technology that can enable the use of alternative resources, reduce the need for transport and present zero waste concepts for the aggregate and concrete industry.
In Norway it is already the situation, as natural aggregate resources near urban centres terminate, that the transport distances increase significantly.
According to information from the Geological Survey of Norway, NGU, (2008)5 it is clear that some of the most important natural sand and gravel resources, e.g. in south-western Norway, and areas serving the Oslo region, will be finished within 10-30 years. It has been emphasised by NGU that there is a clear need to develop a strategy how to preserve important concrete aggregate recourses, and what to do in regions already scarce in natural aggregates.
In a forecast for the aggregate market in US, presented by Vulcan Materials Company (2007)6, it is claimed that the demand for aggregates will continue to grow in the future. The demand will be driven primarily by population growth and the associated requirements for residential and non-residential construction, and the need to upgrade and/or replace aging infrastructure of all types. It is emphasised that it will become more difficult to site and open new quarries, particularly in proximity to high-growth areas. It is also predicted that the need to ship aggregates over greater distances will increase the number of distribution facilities in metropolitan areas. Other issues of consideration in their forecast are:
• The need for aggregate producers to meet tighter specifications, will results in more unusable materials being produced.
• Recycled concrete will continue to play an important role in urban areas; however, recycled materials will remain a small part of the total aggregate supply.
• Community relations issues in the future will remain important and will likely place additional restraints on locating and operating aggregate facilities.