INSTALLING

• Characteristics
• Site Preparation
• Underlayment Installation
• Placing The Block Mats

JOINING

• Cable Clamps
• Looping Cables

ANCHORING

• Ubar Anchors
• X Plate Anchors
• Cable Earth Anchors

FINISHING

• Backfill
• Top Fill/Vegetation
• Grouting
• Maintenance Checks
• Repairs

AN INTRODUCTION

Australian Concrete Cable Block Mats (ACCB) are an articulated concrete block revetment system, developed, to control various types of erosion due to water, wind, or vehicular traffic.
Australian Concrete Mats Installation Guide provides recommendations for the correct installation of Articulating Concrete Cable Block (ACCB) revetment systems. This guide offers a set of instructions for performing those operations that are critical for the proper functioning of ACCB revetment systems. However, installation is the responsibility of the end user.
The recommended installation of ACCB revetment systems is a guide to achieving the intended hydraulic performance and maintaining stability against the erosive forces of flowing water.
Each individual site will vary so it is important to follow the drawings as designed by a certified and registered Professional Engineer. All illustrations and photographs used in this guide are examples of typical situations.
It is the Contractor’s responsibility to maintain safe work practices consistent with WHS (Workplace Health and Safety) regulations and other prevailing safe work practices. This guide is intended to be used in conjunction with all applicable safety regulations and safe work practices and is in no way a replacement thereof.

CHARACTERISTICS

• Articulated Concrete Cable Block Mat (ACCB) system is made up of 1200mm W x 2400mm L mats that can be placed side by side and clamped together to provide one homogeneous erosion protection system.
• The mats consist of individual concrete blocks interlocked by 316 stainless steel cables, or Polypropylene Rope which are embedded into the concrete.
• Individual concrete blocks typically have 290mm square top faces and 390mm square bottoms. The height of each block is 120mm with an open space of 15mm at the base and 115mm at the top.

Installation of Articulated Concrete Cable Block Mat

1. FOUNDATION AND SITE PREPARATION

• All areas to receive the ACCB shall be compacted and graded smooth to facilitate the installation of the articulated concrete block system and ensure that intimate contact (between the slope face, the filter fabric and the entire bottom surface of the ACCB units) is maintained throughout the system.
• Proper excavation, grading and compaction is critical to the performance of the ACCB system.
• Clear the site of holes, debris, roots, rock, vegetation or obstacles.
• Grade and compact the area to create a stable uniform surface so the ground, slope and slope face shall be uniform.
• The ground / slope is to be prepared so that the tops of the blocks will be flush.
• Final design should be signed off by an Engineer or Qualified Site Manager

2. UNDERLAYMENT INSTALLATION (if needed)

• If required, lay a geotextile fabric or similar filter underlayment to support and prevent soil erosion underneath the ACCBs.
• Areas on which geotextile fabric and ACCB units are to be placed shall be constructed to the lines and grades shown on the contract documents and approved by the engineer.
• Ensure no dragging, tearing or damaging of the geotextile.
• Gently place the mats on the geotextile in such a manner to produce a smooth plane surface.
  Ensure that intimate contact with the subsurface (between the slope face, the geotextile fabric and the entire bottom surface of the ACCB units) is maintained throughout the system. This is critical to the systems performance in the field.

3. PLACING THE CABLE BLOCK MATS

The preferred method is to start installation of the ACCB system at the downstream end and proceed upstream, taking care to protect the leading edge against erosive forces. These erosive forces could potentially undermine the system if proper installation procedures are not followed.

No individual unit within the plane of the system shall exceed a 15mm protrusion or greater protrusion than is specified in the contract drawings. The units shall be placed side by side so that the blocks abut. Termination trenches typically consist of a 2-block toe-in, including the top of slope, the toe of slope and flanks unless otherwise directed by the Engineer. This design is typical of an ACCB system to protect all sides from erosive factors.

Subgrade preparation, placement of filter fabric, placement of the ACCB concrete units and the final completed project shall be inspected and approved by the Contractor and Engineer.

3.1 For a Sloped Site Application

• Begin at the base of the slope.
• Ensure the blocks are interconnected correctly and cover the entire slope uniformly.

3.2 For a Channel Application

• Place the articulated concrete blocks along the channel bed and sides, starting upstream and working downstream.
• Ensure that the blocks fit snugly together and conform to the shape of the channel.
• The gap between each mat shall not be greater than 50mm, preferably 15mm or it must be closed using a cement mixture.

3.3 For Placing Mats Over Pipes

• Mats offer greater articulation, and flexibility and protective coverage of the curve of pipe when the mats are placed with the base side facing up.
• When joining mats over pipe, we recommend the use of 2 clamps per loop, each positioned close to the concrete edge. (Refer to joining and anchoring detail for more detail and pics indicating clamps positioning over pipe joins)

3.4 For Underwater Application

When working in an underwater application, it is the contractor’s responsibility to assess the jobsite conditions and the means of achieving proper subgrade preparation, per the Engineer’s Contract drawings, specifications, and tolerances.

3.5 For Causeways and Low water Crossings

• Ensure the water does not go under the mats and scour out the subgrade level.
• Secure mats on the leading edge and toe edge to encourage water to flow over mats.

3.6 For Boat Ramps

• Install to Engineers Design details.
• Ensure a stable base.
• Ensure adequate anchoring

4. SECURING THE CABLE BLOCK MATS

• To join mat units together to form a large footprint, use cable clamps. (Refer to Joining Mats detail)
• Anchor the blocks to the ground by using Ubar Anchors, Threaded Bolts or Cable Earth Anchors, especially on steeper slopes. (Refer to Anchoring Mats detail) or to Engineers detail.
• Secure the blocks firmly to withstand water flow, using anchoring systems as required and designed by the project engineer.
• Perimeter trenching may also be necessary to prevent the system from being undermined during high-velocity stormwater events.

Engineer Specifications

Every project site has its specific needs and requirements and conditions.

Download and refer to the technical drawings as a guide for how to install the Articulated Concrete Cable Block Mat. However, please note that Australian Concrete Mats (ACM) technical drawings, illustrations, notes and anchoring details are to be used as a GUIDE ONLY.

Every soil condition, water flow rate and project have varying parameters. ACM recommend the use and anchoring details be designed specifically by a qualified and certified engineer who is familiar with your site and project conditions.

Joining Articulated Block Mats

• To cover a large footprint area, the mats are placed side by side or end to end
• Mats are joined together using cable clamps on the loops of rope or cable
• Allow at least four cable clamps per mat to join them together
• The standard placement of clamps shall be placed on 800mm centres connecting adjoining mats together.
• Clamps are available sizes:
  • 16mm Clamps for Polypropylene Rope
  • 8mm Clamps for Stainless Steel Cable

Pictured below an individual mat featuring polypropylene rope as interconnecting material. 

Joining Mats by Looping Cables

If clamps are not suitable or unable to be installed due to conditions, a cable could be threaded through the loops to connect mats together.

Pictured to the right, an example of AB Block Mats being joined using both (a.) cable looped cable and (b,) cable clamps on an underwater tidal pipe stabilisation project.

Cable Earth Anchors

• Cable Earth Anchors can be used to secure the mats into the ground.
• An example of a supplier is Hulk Earth Anchors. Their product information is available from the manufacturers website:  www.HulkEarthAnchors.com LINK HERE

5. FINISHING

Any final surface application should not be placed prior to the inspection of the systems clamping and anchoring. It is recommended that after the installation of the mat system, that it be covered with desired backfill.

5.1 Backfill

• Backfill of the block shall be specified by the Project Engineer. Typical backfill is either suitable soil for revegetation or 10 to 20 mm diameter crushed stone. Backfilling should occur as early as possible to protect the filter fabric from UV damage. The exposed edges shall be backfilled until flush, ensuring the integrity of a soil backfill is maintained.
• Termination trenches shall be backfilled to the approved contract drawings. This backfill material shall be approved by the Project Engineer. It is the recommendation by Australian Concrete Mats that this nonerodable backfill be 32MPa non-shrinking grout or concrete.

5.2 Topfill and /or Vegetation (optional)

• Establishing vegetation between the blocks helps with additional stabilisation and ecological benefits if the design performance.
• If vegetation is required, the mat system should be seeded and backfilled. This will allow moisture to traverse back and forth from the sub grade to vegetation.
• If planting vegetation, choose species suitable for the local environment and site conditions.

5.3 Grouting

32MPa non-shrinking grout or 32MPa concrete shall be placed where the loop ends of the mats meet, or wherever there is greater than a 50mm gap between adjacent mats or structures. Grout to the top of the block or slightly lower (not above). Grouting of seams is meant to provide a hydraulic connection, not necessarily a structural connection between mats.

6. FINAL INSPECTIONS AND ADJUSTMENTS

• Any surface application should not be placed prior to the inspection of the systems clamping and anchoring.
• Inspect the installation to ensure complete coverage and stability.
  Make any necessary adjustments to the blocks or vegetation.

7. MAINTENANCE CHECKS

• Regularly inspect the site, especially after significant rainfall or flow changes, to ensure the integrity of the Articulated Concrete Block Mat system. Report any movement to the responsible engineer.
• If subgrade is suitable, the blocks will lend support and an even grade for maintenance vehicles (mowers) to traverse over them.
• Due to their durability and low maintenance requirements, ACCB can save significant ongoing costs by reducing long-term repairs, replacements, and upkeep costs.

8. REPAIR OF DAMAGED UNITS

• In the event that a damaged concrete unit exists prior to the placement or after the mat has been installed, the concrete unit can be repaired in one of the following acceptable manners; unit to be completely removed and then backfilled with 32MPa grout/concrete or, replaced with a new block unit.
• Depending on the size of the crack or chip, the perimeter and void areas of the block can be filled with grout up to or just below the top grade of the block.
• Chipping resulting in a weight loss exceeding 10% of the average weight of a concrete unit shall be repaired. Surface chipping (i.e. weight loss of less than 10%) resulting from customary handling methods generally do not require repair.