Definition List:

Adhesive
Exterior grade construction glue used to bind materials together. Commonly used to glue cap units into position.

Reference: Landscape Retaining Walls, Large Retaining Walls
Angle of Repose
The stable angle that a pile of soil or a slope wishes to remain at. As soil falls off a conveyor to make a pile, the angle it creates represents the natural angle of repose.

Atterberg Limits
The basic measure of the nature of a fine-grained soil. Depending on the water content of the soil, it may appear in four states: solid, semi-solid, plastic and liquid. In each state, the consistency and behavior of a soil is different and consequently so are its engineering properties. They can be used to distinguish between silt and clay, and it can distinguish between different types of silts and clays

Base Material
A base pad of granular material, compacted and leveled to receive the base course of blocks for wall construction.

Reference: Landscape Retaining Walls, Large Retaining Walls
Base Rock
Gravel in varying sizes of angular or smooth aggregates similar to the wall rock used in retaining walls or a road/ paver base type material.
Berm
A raised soil area above the retaining wall that is used to divert water away from the retaining wall.

Reference: Landscape Retaining Walls, Large Retaining Walls
Biaxial
Refers to geogrids that have 100% of their design strength in both directions. See LTADS.

Reference: AB Grid, Large Roll Grid
Bond Beam
Course or courses of the concrete fence that is grouted and usually reinforced in the horizontal direction.
Cantilever
A long projecting beam or girder fixed at only one end, used chiefly in bridge construction.
Chamfer
A beveled or angled edge on the top and sides of the block.

Reference: Landscape Retaining Walls, Large Retaining Walls
Clay Soils
Soil that is composed of very fine or small particles that stick together. Clay soils are very moisture sensitive and will exert more pressure on a wall.

Reference: Landscape Retaining Walls, Large Retaining Walls
Compaction
The act of compressing and consolidating the soil used to construct the retaining wall.

Reference: Landscape Retaining Walls, Large Retaining Walls
Compaction Zone
The area located behind the consolidation zone that runs to the end of the area being disturbed by any construction activities.
Concrete Vibrator
A concrete vibrator is a construction tool used on concrete pouring sites. A vibrator is used to ensure that a pour is even and free of air bubbles so that the concrete will remain strong.
Consolidation Zone
The 3 ft. (0.9 m) area directly behind the back of the block and extending toward the back of the excavated area.

Reference: Landscape Retaining Walls, Large Retaining Walls
Cut and Fill
refers to the activities of handling the soil on a job site. Cut applications require removing soil to allow construction activities where fill applications requires adding soil to behind the wall.

Reference: Landscape Retaining Walls, Large Retaining Walls
Diffracted Noise
The bending of sound waves around obstacles in their path.
Drain Pipe
Used to direct incidental water that makes its way in behind the reinforced mass, and vents it to daylight by creating a channel for the water to flow out from.

Reference: Landscape Retaining Walls, Large Retaining Walls
Efflorescence
The white chalky residue that can form on the face of a block. Does not influence the structural integrity of the system.
Excavate
the process of digging and moving the soil on a job site.

Reference: Landscape Retaining Walls, Large Retaining Walls
Filter Fabric
A geosynthetic material used to separate different soil types.

Reference: Landscape Retaining Walls, Large Retaining Walls
Foundation Pad
A base pad of granular material, compacted and leveled to receive the base course of AB units.
Friction Angle
The measurement of the internal strength of the soil. This is the soil's natural tendency to resist movement.

Geogrid
A manufactured high strength reinforcement grid material that comes in rolls of various sizes and strengths.

Reference: Landscape Retaining Walls, AB Grid, Large Roll Grid
Global Stability
Refers to the overall resistance to landslides or complete slope failure.

Reference: Large Retaining Walls, Retaining Wall Terraces
Grade
Finshed ground level.

Reference: Landscape Retaining Walls, Large Retaining Walls
Gravity Wall
A retaining wall that does not use soil reinforcement. A gravity wall has limited height because it relies on the weight and setback of the block alone to resist the soil pressures behind the wall.

Reference: Landscape Retaining Walls, Large Retaining Walls
Hand Tamper
A tool used for the compaction of crushed stone for a shed base by hand.

Hollow Core
The open void in the block that is filled with wall rock and promotes additional draininage.

Reference: Landscape Retaining Walls, Large Retaining Walls
Infill Soils
The soil used to backfill behind the wall rock in the reinforced zone. These soils need to be identified and approved by a qualified engineer before they can be used. A granular type of material is best.

Reference: Landscape Retaining Walls, Large Retaining Walls
Impermeable Fill
Soils or materials that do not not permit the passage of a fluid through them
Long-Term Allowable Design Strength (LTADS)
Tested strengths of the geogrid that includes reductions for durability, creep, degradation and installation damage. Most grids have 100% of this strength only in one direction.

Reference: Large Retaining Walls
Mortarless
Construction practice that utilizes concrete blocks stacked on top of each other without a mortar joint between them.

Reference: Large Retaining Walls
On-Site Soils
The soil that is native or currently available at the job site
Organic Soils
Usually the top layer of dirt that is dark in color with the higher organic material in it and promotes root growth.

Reference: Landscape Retaining Walls
Plate Compactor
Hand operated machine that uses weight and vibration to compact the soil.

Reference: Landscape Retaining Walls, Large Retaining Walls
Raised Front Lip
Machined edge of Allan Block retaining wall unit that provides block to block connection and setback.
Reflected Noise
The rebounding of sound waves from an obstacle in its path.
Reinforced Soil Mass
The area reinforced with geogrid the includes the block, wall rock and soil to create a mass/weight to resist the soil pressure behind the reinforced zone.
Reinforced Wall
Refers to a wall that uses geogrid reinforcement to provide additional stability to resist the pressures exerted behind the structure. Typically, geogrid is used to build taller retaining walls.

Reference: Landscape Retaining Walls, Large Retaining Walls
Reinforced Zone
Area located directly behind the block that runs to the end of the area being reinforced by any geogrid reinforcement material.
Reinforcement
Typically this refers to the geogrid behind the wall that is used to provide additional stability for taller wall heights. However, this may include no-fines concrete and tie-back systems like earth anchors and soil nails.
Retained Soil Mass
The area of soil behind a retaining wall that is contained by the wall structure.
Retaining Wall
Man-made structure that is built to hold back soil.

Reference: Retaining Walls
Rise & Run
Refers to the slope or incline of a grade change.
Sandy Soils
Soil that is composed of larger particles that you can see and generally don't stick together. Sandy soils drain water easily and will exert less pressure on a wall.

Reference: Landscape Retaining Walls
Seismic Load
in earthquake engineering -it is the application of an earthquake-generated agitation or of force to a structure.
Setback
Refers to the distance a course will offset back into the slope from the course beneath it. Also refered to as the batter of the wall.
Sheet Piles
Sheet piles are driven sheets of metal that use an interlocking connection to obtain a continuous barrier in the ground
Shotcrete
Shotcrete is a concrete sprayed at high velocity over steel cages or wire mesh that creates a concrete structure that can incorporate multiple types of reinforcement such as soil nails, steel mesh, or fiber reinforcement.
Site Elevation
The specific vertical distance from sea level of the current project
Site Plan
Working drawings of the construction activities scheduled for the project
Soil Nails
Soil nailing is a construction technique that can be used to treat unstable natural soil slopes or as a construction technique that allows the safe over-steepening of new or existing soil slopes.
Sonotube
Hollow cardboard cylinder used for forming round concrete columns.
Standard Proctor
A method for determining the moisture-density relationship in soils used in compaction.
Stirrups
A metal device that bears the weight of fence bond beam.
Surcharge
Any added weight above a wall is called a surcharge. Patios, swimming pools and driveways are common surcharges. Your wall may need additional support if a surcharge is present.
Swale
A small ditch formed at the top of the retaining wall to collect and divert water away.
Toe Drain
Usually a 4-inch perforated pipe placed behind and at the base of the wall to collect and carry water away.
Transmitted Noise
Sound that passes through the obstacle in its path.
Wall Envelope
Refers to the area behind the wall the includes the setback distance and reinforcement length.

Reference:Large Retaining Walls
Wall Rock
Compactible aggregate ranging in size from 0.25 in to 1.5 in. (6 mm to 38 mm) with no more than 10% fines. Used for base material, within block cores and behind the block.