Difference between revisions of "Aggregates"

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==Reservoir stone and choker layer==
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[[File:Particle void ratio.png|thumb|The highest void ratio is found in uniformly graded aggregate, as there are no smaller particles to occupy the inter-particle pores.]]
[[File:Particle permeability.png|thumb|Higher permeability is found in larger, angular, uniformly graded aggregate. This is due to larger pore sizes and lower tortuosity.]]
The important characteristics of the stone within the reservoir or [[underdrain]] are the lack of fines, the void ratio and (to a lesser extent) the permeability.
Porosity and permeability are directly influenced by the size, gradation and angularity of the particles <ref>Judge, Aaron, "Measurement of the Hydraulic Conductivity of Gravels Using a Laboratory Permeameter and Silty Sands Using Field Testing with Observation Wells" (2013). Dissertations. 746. http://scholarworks.umass.edu/open_access_dissertations/746</ref>




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Aggregates used to line [[swales]] or otherwise dissipate energy (e.g. in [[forebays]]) should have high angularity to increase the permissible shear stress applied by the flow of water. <ref>Roger T. Kilgore and George K. Cotton, (2005) Design of Roadside Channels with Flexible Linings Hydraulic Engineering Circular Number 15, Third Edition  https://www.fhwa.dot.gov/engineering/hydraulics/pubs/05114/05114.pdf</ref> However, in some surface landscaped applications there may be a desire to use a rounded aggregate such as 'river rock' for aesthetic reasons.
Aggregates used to line [[swales]] or otherwise dissipate energy (e.g. in [[forebays]]) should have high angularity to increase the permissible shear stress applied by the flow of water. <ref>Roger T. Kilgore and George K. Cotton, (2005) Design of Roadside Channels with Flexible Linings Hydraulic Engineering Circular Number 15, Third Edition  https://www.fhwa.dot.gov/engineering/hydraulics/pubs/05114/05114.pdf</ref> However, in some surface landscaped applications there may be a desire to use a rounded aggregate such as 'river rock' for aesthetic reasons.


==Stone mulch==
==Stone mulch==
Stone mulch exists  
Stone mulch exists  
<ref>Simcock, R and Dando, J. 2013. Mulch specification for stormwater bioretention devices. Prepared by Landcare Research New Zealand Ltd for Auckland Council. Auckland Council technical report, TR2013/056 </ref>
<ref>Simcock, R and Dando, J. 2013. Mulch specification for stormwater bioretention devices. Prepared by Landcare Research New Zealand Ltd for Auckland Council. Auckland Council technical report, TR2013/056 </ref>

Revision as of 20:19, 5 March 2018


Stone for erosion control[edit]

Aggregates used to line swales or otherwise dissipate energy (e.g. in forebays) should have high angularity to increase the permissible shear stress applied by the flow of water. [1] However, in some surface landscaped applications there may be a desire to use a rounded aggregate such as 'river rock' for aesthetic reasons.

Stone mulch[edit]

Stone mulch exists [2]

  1. ↑ Roger T. Kilgore and George K. Cotton, (2005) Design of Roadside Channels with Flexible Linings Hydraulic Engineering Circular Number 15, Third Edition https://www.fhwa.dot.gov/engineering/hydraulics/pubs/05114/05114.pdf
  2. ↑ Simcock, R and Dando, J. 2013. Mulch specification for stormwater bioretention devices. Prepared by Landcare Research New Zealand Ltd for Auckland Council. Auckland Council technical report, TR2013/056

Includes the protection of soil from dislocation by water, wind or other agents.

A broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations.

A broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations.

a top dressing over vegetation beds that provides suppresses weeds and helps retain soil moisture in bioretention cells, stormwater planters and dry swales.

a top dressing over vegetation beds that provides suppresses weeds and helps retain soil moisture in bioretention cells, stormwater planters and dry swales.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

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