2507.01 DESCRIPTION.
This construction shall consist of placing a layer of stone or concrete for protection of earth slopes against erosion from stream flow or wave action. This protective layer shall be placed in accordance with the contract documents for the class of revetment specified. When specified, a filter course shall be placed beneath the revetment.

When specified concrete grout shall be furnished, transported, and placed within the voids of rock revetment as shown in the contract documents, the intent is to fill the voids of the revetment rock placement without over consolidation.

2507.02 MATERIAL.

A. Revetment.
Materials for revetment shall meet requirements of Division 41 for the material specified.

B. Grout.

1. Cement.
Cement shall be in accordance with Section 4101, at the rate of 10 sacks (940 pounds) per cubic yard (558 kg per cubic meter).

2. Fly Ash.
Fly Ash shall meet requirements of Section 4108. Fly ash may be substituted for cement for up to 25% by weight (mass) of cement.

3. Fine Aggregate.
Fine Aggregate shall meet requirements of Section 4110. 2100 pounds (surface dry weight) per cubic yard (1246 kg (surface dry weight) per cubic meter).

4. Water.
Water shall meet requirements of Section 4102. 45 gallons (375 pounds) per cubic yard (170 L (221 kg) per cubic meter), or enough to provide a thick creamy consistency.

5. Air-entraining Admixtures.
Air-entraining Admixtures shall meet requirements of Section 4103. 6 to 10%.

6. Liquid Curing Compounds.
Liquid Curing Compounds shall meet requirements of Section 4105 of the Standard Specifications.

The Engineer may require adjustment of the mix proportions to achieve proper solids suspension and optimum flowability. After the mix has been designated, it shall not be changed without approval of the Engineer.

Proportioning and mixing equipment shall meet requirements of Articles 2001.20 and 2001.21. Sufficient mixing capacity of mixers shall be provided to permit the intended pour to be placed without interruption.

C. Filter Blanket.
Article 2107.11 shall apply.

2507.03 CONSTRUCTION.
Revetment construction shall consist of four classes. For all of these classes of revetment, construction shall begin in a trench dug to the elevation shown in the contract documents. The slopes upon which revetment is to be placed shall be shaped and dressed to the extent that, when the revetment is placed to the specified depth, the revetment surface will be in substantial compliance with the lines and grades shown in the contract documents. The Contractor shall mark in a system of grids those areas designated to receive stone protection for control of placement thereon. Loads shall be spotted and distributed over the surface marked in grids to provide the thickness shown in the contract documents. Control of distribution shall be based on the assumed density of 100 pounds per cubic foot (1600 kg/m³) and the actual weights (mass) delivered.

Immediately prior to placing the revetment, the prepared base will be inspected by the Engineer.

After completion of Class A, B, and C revetment, the trench shall be backfilled with material excavated.

A. Class A Revetment.
Class A Revetment shall consist of a layer of the stone specified over the areas indicated in the contract documents.

This layer shall be placed so that each stone is firmly bedded against the bank and in close contact with adjacent stones. The stones need not be laid in courses, but spalls shall be driven into openings remaining after the layer of stone is placed. The thickness of this layer shall be approximately 15 inches (0.4 m), and no portion shall have a thickness less than 12 inches (0.3 m). Portions of individual rocks projecting more than 2 inches (50 mm) above the general contour of the surface shall be chipped to within these limits.

B. Class B Revetment.
Class B revetment shall be placed by bucket, clam shell or other mechanical means in a manner that will uniformly distribute the material as shown on the plans, prevent damage to the filter blanket or fabric and limit disturbance of foundation soils.

C. Class C Revetment.
Class C revetment shall consist of formed concrete blocks placed in the area shown in the contract documents. The dimensions of the block and reinforcement shall be as shown in the contract documents. Concrete shall be Class C pavement mix with a coarse aggregate durability of Class 2 or better.

D. Class D and Class E Revetment.
Class D and Class E Revetment shall meet requirements of Section 4130. Material for filter blanket, if required, shall consist of the specified material placed as shown in the contract documents.

Stone for revetment shall be placed on the filter blanket or, when filter blanket is not required, directly on the prepared slope or area in a manner which will produce a reasonably well graded mass of stone with the minimum practicable percentage of voids. The entire mass of stone shall be placed in conformance with the lines, grades, and thicknesses shown in the contract documents. Revetment shall be placed to its full course thickness at one operation and in such a manner as to avoid displacing underlying material. Placing riprap in layers or by dumping into chutes and similar methods likely to cause segregation will not be permitted.

The larger stones shall be well distributed, and the entire mass of stone should conform approximately to the gradation specified in Section 4130. The revetment shall be placed and distributed so that there will be no large accumulations of either the larger or smaller sizes of stone.

Some roughness in surface is desirable to break up wave action and decrease the velocity of the water, but the mass should be fairly compact with all sizes of material placed in their proper proportions. Hand placing or rearranging of individual stones by mechanical equipment may be required to the extent necessary to secure the results specified.

When the embankment is constantly exposed to erosion, the riprap protection shall be placed in conjunction with the construction of the embankment with only sufficient lag to allow for proper stabilization of the embankment. Care shall be exercised to prevent mixture of embankment and revetment materials. When the embankment to be protected is constructed in lifts, revetment can be dumped directly in place from the surface of each lift.

E. Bank Shaping.
When the revetment is to be placed on an existing slope, the foundation shall be prepared for areas on which the revetment is to be placed by shaping, trimming, and dressing in reasonable conformance to the slopes, grades, and cross sections shown in the contract documents. Where such areas are high or low, they shall be brought to reasonable conformance by cutting and filling, and the earth shall be well compacted.

F. Erosion Stone.
Erosion stone shall meet requirements of Section 4130. The material shall be placed as shown in the contract documents.

G. Grouting.

1. Placement of Grout.
The grout shall not be placed until the revetment has been inspected and approved by the Engineer.

The rock to be grouted shall be flushed with high pressure water to remove the fines prior to placing the grout. Rock to be grouted shall be kept wet for at least 2 hours immediately prior to grouting, but the grout shall not be placed in standing or flowing water.

The grout mix shall be delivered to the site and placed within 1 1/2 hours after the introduction of cement to the aggregates. Concrete shall be conveyed from the mixer to final placement by any reasonable means which prevent segregation of the aggregate or loss of mortar. Grout shall not be dropped more than 5 feet (1.5 m) vertically unless suitable equipment is used to prevent segregation.

Grout shall be placed in successive lateral courses starting at the top and progressing to the toe. The grout shall be discharged directly on the surface of the rock. The flow of grout shall be directed to prevent it from flowing excessively along the same path and to assure that all intermittent spaces are filled. Sufficient jarring of rocks may be done to aid penetration of the grout so that all voids shall be filled and the grout fully penetrates the rock blanket. Grout shall be worked into voids with the use of suitable spades and rods.

A smooth surface shall not be created by the grouting operation. The finished grout shall leave face stones exposed for one-fourth to one-third of their depth. Revetment rock blankets shall be finished by brooming or other method to fill voids caused by sloughing, eliminate runs, and provide a rough surface.

2. Curing and Protection.
After completion of any course, no load shall be permitted on the grouted surface for a period of 24 hours. The grouted surface shall be protected from injurious action by the sun, rain, flowing water, and mechanical injury.

The grouted surface shall be prevented from drying for a curing period of at least 7 days after placement. Exposed surfaces shall be kept moist for the entire period, or until curing compound is applied. Moisture shall be maintained by sprinkling, flooding, fog spraying, or covering with continuously moistened canvas, cloth mats, straw, sand, or other approved material.

The compound shall be sprayed on the moist finished concrete surface as soon as free water has disappeared. The compound shall be applied at a uniform rate of not less than 1 gallon per 15 square yards (3 L per 10 m²) of surface, and shall form a continuous adherent membrane over the entire surface. Curing compound shall not be applied to surfaces requiring bond to subsequently placed concrete.

3. Limitation of Operations.

a. Grout shall not be placed on frozen ground.

b. Grout batching, mixing, and placing may be started, if weather conditions are favorable, when the temperature is at least 34°F (1°C) and rising. At time of placement, grout must have a temperature of at least 40°F (4°C). Mixing and placing shall stop when the temperature is 38°F (3°C) or less and falling.

c. Each placement course shall be as continuous an operation as possible.

4. Inspecting and Testing Fresh Grout.
The Engineer will inspect materials and processes used in mixing and placing the grout, as well as secure samples for air content. The Engineer shall have free entry to all parts of the Contractor's plant and equipment.

When ready-mixed grout is furnished, the Contractor shall furnish to the Engineer a statement-of-delivery ticket for each batch delivered to the job site. The ticket shall show the batch weights (mass) of cement, fly ash if used, water, fine aggregate, and air entraining agent. Time of loading and revolution counter reading at the time of batching shall also be shown.

2507.04 METHOD OF MEASUREMENT.
The quantity of Class A or C revetment will be computed by the Engineer in square yards (square meters) from measurements of the surface as constructed to the nearest 0.1 foot (0.1 m).

Class B, D, and E revetment and Erosion Stone will be measured in tons (megagrams) to the nearest 0.1 ton (0.1 Mg). Only material placed in accordance with the contract documents will be measured.

Material for a filter blanket will be measured in tons (megagrams) to the nearest 0.1 ton (0.1 Mg).

The quantity of engineering fabric will be computed in square yards (square meters) from measurements of the material placed to the nearest 0.1 foot (0.1 m).

When Concrete Grout for Revetment or Gabion is specified in the contract documents, the Engineer will compute the volume of concrete grout furnished and placed, from the nominal volume of each batch and a count of batches. Grout unused or wasted will be estimated and deducted by the Engineer; however, no deduction will be made for a partial batch remaining at the completion of the operation.

2507.05 BASIS OF PAYMENT.
For the construction of revetment of the class specified, the Contractor will be paid as follows:

For the quantity of revetment furnished and placed, the Contractor will be paid the contract unit price per square yard (square meter) for Class A or C revetment, or per ton (megagram) for Class B, D, or E revetment and Erosion Stone.

For the quantity of granular material for filter blanket placed, the Contractor will be paid the contract unit price per ton (megagram).

For the quantity of engineering fabric placed, the Contractor will be paid the contract unit price per square yard (square meter).

For bank shaping, if required, the Contractor will be paid the lump sum contract unit price.

When excavation, backfill, and (if required) special compaction are designated in the contract documents, payment will be made in accordance with the type of work specified.

These payments shall be full compensation for all work, including bank shaping, furnishing and placing all material, excavation and backfilling, and for furnishing all equipment, tools, and labor necessary to complete the work according to the contract documents.

When Concrete Grout for Revetment or Gabion is specified in the contract documents, the Contractor will be paid the contract unit price per cubic yard (cubic meter). This payment shall be full compensation for placing the grout and for furnishing all materials, equipment, and labor necessary to complete the work.