857CONCRETE BLOCK REVETMENT SYSTEMS

857.1DESCRIPTION—This work is construction of an articulating system of interlocking precast concrete

blocks or cable-connected precast concrete block mats for erosion protection of slopes and channels.

857.2MATERIAL—

strength of 4,000 pounds per square inch and an absorption of 6% or less when tested according to ASTM C140 and a minimum durability factor of 80 when tested according to ASTM C666 (Procedure A, freezing and thawing in water).

• Seeding and Soil Supplements—Section 804

• Mulching—Section 805

• Rolled Erosion Control Products—Section 806.2(a)

furnished meets hydraulic performance characteristics, derived from tests conducted under controlled flow conditions and conforming to U.S. Federal Highway Administration and U.S. Bureau of Reclamation Testing protocol, as documented in “Hydraulic Stability of Articulating Concrete Block Revetment Systems During Overtopping Flow,” Report No. FHWA-RD-89-199.

shipping. Store and handle in a manner that protects them from damage by construction activities or traffic.

857.3CONSTRUCTION—Excavate to allow placement of the geotextile and concrete blocks as indicated

or directed. Remove obstructions such as tree roots, projecting stones, or other foreign matter to a depth of 6 inches below subgrade. Grade the slope to a smooth surface. Backfill voids or soft areas with suitable material and compact to non -movement. Fine g rade the area and hand dress, where necessary, before placing the geotextile. Place geotextile as specified in Section 212.3(d)2. Place concrete blocks over a geotextile, according to the system manufacturer’s instructions. Submit field samples to LTS to verify that the manufacturer’s prescribed geotextile is installed. Secure cable connected concrete block systems to the slope with soil anchors as indicated or directed. Do not use unsound or damaged blocks. Minor cracks, incidental to the usual methods of manufacturer, or minor chipping resulting from shipment and delivery are not grounds for rejection unless the Representative determines the material unacceptable. After placing blocks, backfill the open areas of the block with topsoil or aggregate, as indicated, to the top of the blocks. Complete backfilling within 7 days of placing the geotextile. If using aggregate, size aggregate according to the manufacturer’s recommendation. If using topsoil, seed

the backfill area as specified in Section 804 and mulch as specified in Section 805. Use Rolled Erosion Control Products (RECP), as specified in Section 806.2(a), to establish vegetation in a wet weather channel as directed.

857.4MEASUREMENT AND PAYMENT—

Aggregate backfill, if used, is incidental to the work.