§ 646S.3. Materials

A.

Portland Cement (p.c.) Concrete

The Portland cement concrete shall be Class B and shall conform to Standard Specification Item No. 403S, "Concrete for Structures".

Air entrainment admixtures shall be used in the p.c. concrete mix and shall conform to Standard Specification Item No. 405, "Concrete Admixtures". With prior approval of the Engineer or designated representative, retarding admixtures may be used. Concrete sand and crushed stone or gravel passing 3/8 inch US Standard (SI sieve designation of 9.5 mm) sieve shall be used for the concrete mix design.

B.

Revetment Rope

Revetment Rope shall be constructed of high tenacity, low elongation, continuous filament polyester fibers, consisting of parallel core fibers, which are contained within an outer braid jacket or cover.

The outer cover shall consist of an 8, 10, 12 or 16 strand braid covering the core fibers.

The weight (mass) of the core shall be between 65 percent and 75 percent of the total weight (mass) of the rope.

Construction of the rope shall be such that the cover braid is non-load bearing and the rope is torque free.

Mininum average breaking strengths for new, dry rope and the minimum and maximum weights (mass) for the rope are as follows:

Rope Diameter			Circumference		Minimum		Minimum
Nominal inches	Actual				Weight, lbs. Per 100 ft.	Mass, kgs. per 100 m	Breaking Strength
	Ins.	mm	Ins.	mm			lbs.	kNs.
3/16			.589	15	1.3	1.9	1,600	7.1
¼	.240	6.1	.754	19	2.1	4.1	2,750	12.2
¼	.255	6.5	.801	20	2.6	5.0	3,300	14.7
¼	.280	7.1	.880	22	2.9	5.6	4,000	17.8
¼	.295	7.5	.927	24	3.1	6.0	4,500	20.0
5/16	.32	8.1	1.005	27	4.2	8.1	6,000	26.7
3/8	.380	9.6	1.194	30	5.0	9.7	8,800	39.1
½	.5	12.7	1.571	40	9.4	18.2	14,000	62.3

 

Elongation requirements specified below are based upon stabilized new, dry rope. Stabilization refers to a process in which the rope is cycled 50 times between a load corresponding to 200D square and a load equal to 10 percent, 20 percent or 30 percent of the rope's approximate average breaking strength. Relevant elongation values are as shown in the table below. The tolerance on these values is plus or minus 5 percent.

	Percent Breaking Strength
	10%	20%	30%
Permanent Elongation While Working	0.7%	1.8%	2.6%
Elastic Elongation	0.6%	1.4%	2.2%
Total Stretch	1.3%	3.2%	4.8%

 

The critical temperature, defined as the point at which degradation of the rope occurs due to temperature alone, shall be a minimum of 3500F (1770C). The melting point of the rope materials shall be a minimum of 4800F(2490C).

C.

Anchors and Miscellaneous Hardware

Anchors shall be screw type helix anchors and shall conform to ASTM A-36. Anchor size, length and spacing shall produce a direct pull equivalent to the dead weight (mass) of the mats. The anchors shall be galvanized in accordance with ASTM A-123. Clips, sleeves and other miscellaneous hardware shall be aluminum.

Filter fabric shall be placed below the revetment conforming to Item No. 620S, "Filter Fabric".

D.

Blocks and Mats

Cellular concrete blocks shall be cast to the dimensions of 4 inches (100 mm) by 11 7/8 (300 mm) inches by 23 7/8 inches (600 mm) nominal, with a minimum weight of 35 to 40 pounds per square foot (170 to 195 kilograms per square meter). (OPTIONAL: Each mattress shall contain a nonabrasive plastic tubing incorporated into the system continuously longitudinally and laterally.) The blocks shall have cells and outer recesses in the vertical direction. (OPTIONAL: Vertical cells may be eliminated in certain specified projects.)

The blocks shall be assembled into mats of length and width to fit the proposed work. The blocks shall be bound into mats by the use of the revetment rope. Two strands of rope shall extend through each block in a longitudinal direction and 1 strand of rope shall extend through each block in a lateral direction.

Each longitudinal rope will be looped at one end of each row of blocks and the ends bound together at the opposite end of each row. The binding of the rope ends shall be by sleeves. Lateral rope shall extend approximately 6 inches (150 mm) past the outer recesses of the mat and shall be held in place by buttons or similar devices.

Longitudinal ropes shall be a minimum ¼ inch (6.3 mm) diameter for mats up to 50 feet (15 meters) in length and 5/16 inch (7.8 mm) for mat lengths in excess of 50 feet (15 meters). Rope used in the transverse direction shall be ¼ inch (6.3 mm) in diameter.