Description
Overview
AJs are high stability concrete armour units that are
used in river, lake, and coastal applications to control erosion, stabilize
shorelines, and provide habitat. In open channel applications they are used
for bank and toe protection, flow and grade control, bridge pier scour
protection, energy dissipation, and habitat. These small units may be
fabricated in standard block machines. In coastal applications AJs are
typically used for reefs, revetments, breakwaters, and jetties and may also be
used to provide habitat. The photographs below show a range of AJ sizes from 600 mm (35
kg) to 2400 mm (3.6 tonne).
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Stability
AJs have a high degree of interlock and porosity, leading to
high stability coefficients in waves and currents. Units may be
placed in random or uniform patterns.
Fabrication
AJs are designed to optimize fabrication efficiency. The
geometry allows for the use of very simple forms. Smaller sized
units can be manufactured in conventional block machines which
significantly reduces fabrication costs. Units may also be flat
cast, fabricated in gang molds, and in 3D clam shell molds.
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River and Coastal AJs
AJs are used in both river and coastal applications. Structural
loads are significantly higher in coastal applicatons and thicker
AJs which are more structurally robust are used. These slender
and thick AJs are termed River units and Coastal units.
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Economics
AJs are placed in a single layer and have high hydraulic stability.
This, combined with simple fabrication and efficient placement
methods, make AJs both a stable and cost effective armour unit.
Additional Information
This web site provides basic information on the use of AJs in river
and coastal applications. If you have any questions regarding the use or
specification of AJs, past projects, design aids, or fabrication and
construction methods, please do not hesitate to
contact us.