revetment_mat_specs_11_pages.docx

SPECIFICATIONS FOR

ARTICULATING CONCRETE

BLOCK REVETMENT SYSTEM

1.0 SCOPE

This specification covers the construction and delivery of a precast cellular concrete erosion control system in accordance with the lines, grades, design and dimensions shown on the Drawings and as specified herein.

2.0 SPECIFICATIONS

Concrete

Calcined Natural Pozzolan for Use in Concrete

3.0 MANUFACTURER CRITERIA

The manufacturer supplying the requested revetment mat system must meet the following:

a. Manufacturer must be ISO 9001 certified at the time of bid.

b. Manufacturing plant must be PCI certified at the time of bid.

c. Manufacturer must not have defaulted on any contract within the last five years.

d. Manufacturer must be pre-approved prior to bidding.

4.0 DESIGN CRITERIA

The cellular concrete erosion control system shall meet the following criteria.

All cellular concrete mats shall be prefabricated as an assembly of concrete blocks, with specific hydraulic capacities, laced with revetment cables. Cellular concrete mats may be assembled on-site by hand-placing the individual units with the subsequent insertion of cables.

4.1 GENERAL

a. The mats shall be constructed of open cell units only as shown on the drawings.

b. The open cell units have two (2) vertical openings of rectangular cross section with sufficient wall thickness to resist breakage during shipping and installation.

c. The open cell units have an open area of 18-23% as measured from the base of the mat.

d. Parallel strands of cable shall extend through two (2) cable ducts in each block allowing for longitudinal binding of the units within the mat and subsequent ability of the blocks to move freely along the cable.

e. Each row of units shall be laterally offset by one-half of a block width from the adjacent row so that any given block is cabled to four other blocks (two in the row above and two in the row below).

f. All blocks in any given mat must be secured with a minimum of two (2) cables each

g. Each block shall incorporate interlocking surfaces that minimize lateral displacement of the blocks within the mats when they are lifted by the longitudinal revetment cables.

h. The interlocking surfaces must not protrude beyond the perimeter of the blocks to such an extent that they reduce the flexibility or articulation capability of the cellular mats or become damaged or broken when the mats are lifted during shipment or placement.

i. Once the mats are in place, the interlocking surfaces shall minimize the lateral displacement of the blocks even if the cables should become damaged or removed.

j. The mats must be able to flex a minimum of 18° between any given row or column of blocks in the uplift direction and a minimum of 45° in the downward direction.

k. The cables inserted into the mats shall form lifting loops at one end of the mat with the corresponding cable ends spliced together to form a lifting loop at the other end of the mat.

l. Design calculations for the Working Load Limit of the wire rope and splice connections shall be submitted to the Engineer for approval prior to use of the materials.

m. The cables shall be inserted after sufficient time has been allowed for the concrete to complete the curing process.

n. The cellular concrete mats shall be placed on a filter fabric as specified herein. Under no circumstances shall the filter fabric be affixed (i.e. chemically bonded to the blocks) to the mattress in a manner in which would jeopardize the functionality of the filter fabric.

o. The filter fabric shall be independent of the block system.

4.2 PERFORMANCE

a. The design of the cellular concrete mats shall be in accordance with the Factor-of-Safety design methodology as described in "Erosion and Sedimentation" by Pierre Julien, Cambridge University Press, 1995. The minimum designed safety factor shall be 1.5 by utilizing the following equation.

SF = ((2 / 1) ) / ((1 - 2)0.5 cos + (2 / 1) + (3 Fd’ cos + 4 Fl’) / 1Ws) = 1.5

The analysis shall be performed based upon the stability of the mat due to gravity forces alone, neglecting conservative forces added by cabling, mechanical anchorage, contact with adjacent blocks, or other restraints not attributable to gravity based forces. The analysis must account for a 0.0-inch block projection. Hydraulic jump analysis based on the correlation between energy ratio and Froude ratio shall also be performed.

b. All design calculations submitted must be based upon the smallest block utilized in the mats. Partial “half blocks” must be analyzed separately

5.0 MATERIALS

5.1 CONCRETE-GENERAL

Materials shall conform to the following applicable ASTM specifications:

a. Portland Cements - ASTM C 150, for Portland Cement.

b. Coarse aggregates used in the concrete mix design will conform to ASTM C33

c. Blended Cements - ASTM C 595, for Blended Hydraulic

d. Hydrated Lime Types - ASTM C 207, for Hydrated Lime Types.

e. Pozzolans - ASTM C 618, for Fly Ash and Raw or Calcined Natural Pozzolans for use in Portland Cement Concrete

5.2 AGGREGATES

Aggregates shall conform to the following ASTM specifications, except that grading requirements shall not necessarily apply:

a. Normal Weight - ASTM C 33, for Concrete Aggregates.

5.3 COLD WEATHER CONCRETE

a. Cold weather concrete placement will be in accordance with ACI 306.

b. Concrete will not be placed if ambient temperature is expected to be below 35 degrees F. during the curing period unless heat is readily available to maintain the surface temperature of the concrete at least 45 degrees F.

c. Materials containing frost or lumps of frozen materials will not be used.

5.4 HOT WEATHER CONCRETE

a. The temperature of the concrete will not exceed 95 degrees F. at the time of placement. When the ambient reaches 90 degrees F. the concrete will be protected with moist covering.

5.5 PHYSICAL REQUIREMENTS

a. At the time of delivery to the work site, the units shall conform to the physical requirements prescribed in Table 2 listed below.

TABLE 2. PHYSICAL REQUIREMENTS

Compressive Strength Net Area Min. p.s.i (mPa) Water Absorption Max. lb/ft3 (kg/m3)

b. Units will be sampled and tested in accordance with ASTM D 6684-04, Standard Specification for Materials and Manufacture of Articulating Concrete Block (ACB) Revetment Systems.

c. Units shall be sampled and tested in accordance with ASTM D 6684-04, Standard Specification for Materials and Manufacture of Articulating Concrete Block (ACB) Revetment Systems.

5.6 VISUAL INSPECTION

a. All units shall be sound and free of defects that would interfere with either the proper placement of the unit or impair the performance of the system. Surface cracks incidental to the usual methods of manufacture, or surface chipping resulting from customary methods of handling in shipment and delivery, shall not be deemed grounds for rejection.

b. Cracks exceeding 0.25 inches (.635 cm) in width and/or 1.0 inch (2.54 cm) in depth shall be deemed grounds for rejection.

c. Chipping resulting in a weight loss exceeding 10% of the average weight of a concrete unit shall be deemed grounds for rejection.

d. Blocks rejected prior to delivery from the point of manufacture shall be replaced at the manufacturer's expense. Blocks rejected at the job site shall be repaired with structural grout or replaced at the expense of the contractor.

5.7 SAMPLING AND TESTING

a. The purchaser or their authorized representative shall be accorded proper access to facilities to inspect and sample the units at the place of manufacture from lots ready for delivery.

b. Field installation procedures shall comply with the procedures utilized during the hydraulic testing procedures of the recommended system. All system restraints and ancillary components (such as synthetic drainage mediums) shall be employed as they were during testing. For example, if the hydraulic testing installations utilize a drainage layer then the field installation must utilize a drainage layer; an installation without the drainage layer would not be permitted.

c. The theoretical force-balance equation used for performance extrapolation tends for conservative performance values of thicker concrete units based on actual hydraulic testing of thinner units. When establishing performance values of thinner units based on actual hydraulic testing of thicker units, there is a tendency to overestimate the hydraulic performance values of the thinner units. Therefore, all performance extrapolation must be based on actual hydraulic testing of a thinner unit then relating the values to the thicker units in the same “family” of blocks.

d. Additional testing, other than that provided by the manufacturer, shall be borne by the purchaser.

6.0 MANUFACTURER

6.1 MIXING AND DELIVERY OF CONCRETE

a. Mixing and delivery of concrete will be in accordance with ASTM C94

6.2 PLACING AND CONSOLIDATING CONCRETE

a. Concrete will be consolidated by the use of mechanical vibrators.

b. Vibration will be sufficient to accomplish compaction but not to the point that segregation occurs.

6.3 FINISHING CONCRETE

a. All exposed surfaces will be floated and troweled to provide a surface free of major defects.

6.4 CRACKS AND PATCHING

a. Cracks in concrete components which are judged to affect the structural integrity of the block will be rejected.

b. Small holes, depressions and air voids will be patched with a suitable material. The patch will match the finish and texture of the surrounding surface.

c. Patching will not be allowed on defective areas if the structural integrity of the block is affected.

6.5 CURING AND HARDENING CONCRETE

a. Concrete surfaces will not be allowed to dry out from exposure to hot, dry weather during initial curing period.

6.6 REVETMENT CABLE AND FITTING

a. Option 1 - Polyester Revetment Cable and Fittings: Revetment cable shall be constructed of high tenacity, low elongating, and continuous filament polyester fibers. Cable shall consist of a core construction comprised of parallel fibers contained within an outer jacket or cover. The weight of the parallel core shall be between 65% to 70% of the total weight of the cable. The revetment cable shall have the following physical properties:

Polyester Cable

Nominal Cable Diameter

Approximate Average Strength

Weight per Length

b. Elongation requirements specified below are based upon stabilized new, dry cable. Stabilization refers to a process in which the cable is cycled fifty (50) times between a load corresponding to 200D2 and a load equal to 10%, 20% or 30% of the cable's approximate average breaking strength. Relevant elongation values are as shown in the table below. The tolerance on these values is + 5%.

ELASTIC ELONGATION

at Percentage of Break Strength

c. The revetment cable shall exhibit resistance to most concentrated acids, alkalis and solvents. Cable shall be impervious to rot, mildew and degradation associated with marine organisms. The materials used in the construction of the cable shall not be affected by continuous immersion in fresh or salt water.

d. Selection of cable and fittings shall be made in a manner that insures a safe design factor for mats being lifted from both ends, thereby forming a catenary. Consideration shall be taken for the bending of the cables around hooks or pins during lifting. Revetment cable splicing fittings shall be selected so that the resultant splice shall provide a minimum of 60% of the approximate average rated cable strength. Fittings such as sleeves and stops shall be aluminum and washers shall be galvanized steel unless otherwise shown on the Drawings.

e. Option 2 - Galvanized Steel Revetment Cable and Fittings: Revetment cable shall be constructed of preformed galvanized aircraft cable. The cables shall be made from individual wires and strands that have been formed during the manufacture into the shape they have in finished cable.

f. Cable shall consist of a core construction comprised of seven (7) wires wrapped within seven (7) or nineteen (19) wire strands. The revetment cable shall have the following physical properties:

Galvanized Cable

(in.)

g. The revetment cable shall exhibit resistance to mild concentrations of acids, alkalis, and solvents. Fittings such as sleeves and stops shall be aluminum, and the washers shall be galvanized steel. Furthermore, depending on material availability, the cable type (7x7 or 7x19) can be interchanged while always ensuring the required factor of safety for the cable.

h. Selection of cable and fittings shall be made in a manner that insures a safe design factor for mats being lifted from both ends, thereby forming a catenary. Consideration shall be taken for the bending of the cables around hooks or pins during lifting. Revetment cable splicing fittings shall be selected so that the resultant splice shall provide a minimum of 75% of the approximate average rated cable strength.

6.7 ANCHORS

a. Where permanent anchoring is required, e.g. hanging mats on steep slopes without toe construction, the cables (polyester or steel) shall be attached to the anchoring system as indicated on the Drawings. The design and layout of the anchored system design shall be submitted to the Engineer for approval.

6.8 FILTER FABRIC

a. The geotextile filter shall meet the minimum physical requirements listed in Table No. 3 of these Specifications. Consultation with the manufacturer is recommended.

b. The geotextile must be permitted to function properly by allowing relief of hydrostatic pressure; therefore fine soil particles shall not be allowed to clog the filter fabric.

c. The geotextile fiber shall consist of a long-chain synthetic polymer composed of at least 85 percent by weight of propylene, ethylene, ester, or amide, and shall contain stabilizers and/or inhibitors added to the base plastic, if necessary, to make the filaments resistant to deterioration due to ultraviolet and heat exposure. The edges of the geotextile shall be finished to prevent the outer fiber from pulling away from the geotextile.

d. The Contractor shall furnish the Engineer, in duplicate, manufacturer's certified test results showing actual test values obtained when the physical properties are tested for compliance with the specifications.

e. During all periods of shipment and storage, the filter fabric shall be protected from direct sunlight, ultraviolet rays and temperatures greater than 140 degrees Fahrenheit. To the extent possible, the fabric shall be maintained wrapped in its protective covering. The geotextile shall not be exposed to sunlight, ultraviolet rays until the installation process begins.

TABLE 3. PHYSICAL REQUIREMENTS

Grab Tensile Strength (Unaged Geotextile)

(in any principal direction)

Breaking Elongation (Unaged Geotextile)

(in any principal direction)

f. At the time of installation, the filter fabric shall be rejected if it has been removed from its protective cover for over 72 hours or has defects, tears, punctures, flow deterioration, or damage incurred during manufacture, transportation or storage. With the acceptance of the Engineer, placing a filter fabric patch over the damaged area prior to placing the mats shall repair a torn or punctured section of fabric. The patch shall be large enough to overlap a minimum of three (3) feet in all directions.

6.9 CELLULAR CONCRETE MAT SIZE

a. General: The cellular concrete blocks, cables and fittings shall be fabricated at the manufacturer or another approved location into mats with a width of up to eight (8) feet and a length up to forty (40) feet, which is approved by the Engineer.

b. Mat Length: The cellular concrete mats shall have the ability for fabrication in various lengths, widths, and in combinations of length and/or widths. Special mats are a combination of two opposing dimensions either in the longitudinal or transverse direction of the mats. The special mats are available in various dimensions that allow for a custom fit to a site-specific project.

7.0 DELIVERY

7.1 Scope of Work

a. Work specified under this Section includes the delivery of Articulating Concrete Block Revetment Systems.

7.2 Location

It’s the responsibility of the customer to:

a. Provide clear and level site free of overhead and/or underground obstructions

b. Provide access to the site for truck delivery and sufficient area for the crane to install and the equipment to perform the contract requirements.

7.3 Access to Site

a. Delivery to site made on normal highway trucks and trailers. If at the time of delivery conditions of access are hazardous or unsuitable for truck and equipment due to weather, physical constraints, roadway width or grade, an alternate site with better access provided to ensure a safe and quality installation.