432Riprap

2.1 Concrete Riprap . Use Class B concrete unless otherwise shown on the plans.

2.2 Pneumatically Placed Concrete Riprap . Use Class II concrete that meets the requirements of Item 431,

unless otherwise shown on the plans.

2.3 Stone Riprap. Use durable natural stone with a bulk specific gravity of at least 2.50 as determined in

accordance with Tex -403-A , unless otherwise shown on the plans. Provide stone that, when tested in accordance with Tex-411-A , has weight loss of no more than 18% after five cycles of magnesium sulfate solution. Perform a size verification test on the first 5,000 sq. yd. of finished riprap stone for all types of stone riprap at a location determined by the Engineer. Test the riprap stone in accordance with ASTM D5519, Test Method D, unless otherwise directed. Additional tests may be required. Do not place additional riprap until the initial 5,000 sq. yd. of riprap has been approved. Provide grout or mortar in accordance with Item 421 when specified. Provide grout with a consistency that will flow into and fill all voids. Provide filter fabric in accordance with DMS -6200 . Provide Type 2 filter fabric for protection stone riprap, unless otherwise shown on the plans. Provide Type 2 filter fabric for Type R, F, or Common stone riprap when shown on the plans.

2.3.1 Type R . Use stones between 50 and 250 lb., with at least 50% of the stones heavier than 100 lb.

2.3.2 Type F . Use stones between 50 and 250 lb., with at least 40% of the stones heavier than 100 lb. Use stones

with at least one broad flat surface.

2.3.3 Common. Use stones between 50 and 250 lb. Use stones that are at least 3 in. in their least dimension. Use

stones that are at least twice as wide as they are thick. When shown on the plans or approved, material may consist of broken concrete removed under the Contract or from other approved sources. Cut exposed reinforcement flush with all surfaces before placement of each piece of broken concrete.

2.3.4 Protection . Use boulders or quarried rock that meets the gradation requirements shown in Table 1. Both the

width and the thickness of each piece of riprap must be at least 1/3 of the length. When shown on the plans or as approved, material may consist of broken concrete removed under the Contract or from other approved 606 sources. Cut exposed reinforcement flush with all surfaces before placement of each piece of broken concrete. Determine gradation of the finished, in-place, riprap stone under the direct supervision of the Engineer in accordance with ASTM D5519, Test Method D, unless otherwise directed. Table 1 In-Place Protection Riprap Gradation Requirements Nominal Size Maximum Weight (lb.) 90% Weight1 (lb.) 50% Weight2 (lb.) Minimum 8% Weight3 (lb.) 12 in. 200 80–180 30–75 3 15 in. 320 170–300 60–165 20 18 in. 530 290–475 105–220 22 21 in. 800 460–720 175–300 25 24 in. 1,000 550–850 200–325 30 30 in. 2,600 1,150 –2,250 400–900 40 36 in. 4,400 2,200 –3,900 800–1,700 140 1. The 90% weight is the stone weight heavier than 90% of the individual riprap stones, and lighter than 10% of individual riprap stones . 2. The 50% weight is the stone weight heavier than 50% of individual riprap stones, and lighter than 50% of individual riprap stones . 3. The 8% weight is the stone weight heavier than 8% of individual riprap stones, and lighter than 92% of individual riprap stones . The Engineer may require in- place verification of the stone gradation. Determine the in- place gradation of the riprap stone by taking linear transects along the riprap and measuring the intermediate axis of the stone at select intervals. Place a tape measure along the riprap and determine the intermediate axis size of the stone at 2-ft. intervals. Measure at least 100 stones, either in a single transect or in multiple transects, then follow ASTM D5519, Test Method D to determine the gradation, unless otherwise directed. Table 2 is a guide for comparing the stone size in inches to the stone weight shown in Table 1. Table 2 Protection Riprap Stone Size1 Nominal Size Dmax (in.) D90 (in.) D50 (in.) D8 (in.) 12 in. 13.76 10.14 –13.29 7.31–9.92 3.39 15 in. 16.10 13.04 –15.75 9.21–12.91 6.39 18 in. 19.04 15.58 –18.36 11.10 –14.21 6.59 21 in. 21.85 18.17 –21.09 13.16 –15.75 6.88 24 in. 23.53 19.28 –22.29 13.76 –16.18 7.31 30 in. 32.36 24.65 –30.84 17.34 –22.72 8.05 36 in. 38.56 30.61 –37.04 21.85 –28.09 12.22 1. Based on a specific gravity of 2.5 and using the following equation for the intermediate axis diameter : D = ( 12 in./ft.)*{(W)/(Gs*62.4*0.85)}1/3 where: D = intermediate axis diameter ( in.) W = weight of stone ( lb.) Gs = Specific g ravity of stone Note —If the specific gravity of the stone is greater than 2.5, then the above equation can be used to determine the appropriate size using the actual specific gravity. When bedding is required, provide bedding stone that, in place, meets the gradation requirement s shown in Table 3 or as otherwise shown on the plans. If the nominal size of the protection riprap is less than or equal to 30 in., verify the gradation of the bedding material in accordance with Tex -401-A unless otherwise directed. If the nominal size of the protection riprap is equal to 36 in., verify the gradation of the bedding material in accordance with ASTM D5519, Test Method D, unless otherwise directed. 607 Table 3 Protection Riprap Bedding Material Gradation Requirements Nominal Size <36 in. Nominal Size = 36 in. Sieve Size (Sq. Mesh) % by Weight Passing Sieve Size (Sq. Mesh) % by Weight Passing 3” 100 6” 100 1-1/2” 50–80 4” 35–75 3/4” 20–60 3” 45–60 #4 0–15 2” 0–15 #10 0–5 – –

2.4 Cement -Stabilized Riprap . Provide aggregate that meets the requirements of Item 247, “Flexible Base,” for

the type and grade shown on the plans. Use cement -stabilized riprap with 7% hydraulic cement by dry weight of the aggregate unless otherwise directed.

2.5 Special Riprap . Furnish materials for special riprap as shown on the plans.

3.1 Concrete Riprap . Reinforce concrete riprap with 6 × 6 – W2.9 × W2.9 welded wire fabric or with No. 3 or

No. 4 reinforcing bars spaced at a maximum of 18 in. in each direction unless otherwise shown on the plans . Alternative styles of welded wire fabric that provide at least 0.058 sq. in. of steel per foot in both directions may be used if approved. A combination of welded wire fabric and reinforcing bars may be provided when both are permitted. Provide a minimum 6- in. lap at all splices. Provide horizontal cover of at least 1 in. and no more than 3 in. at the edge of the riprap. Place the first parallel bar no more than 6 in. from the edge of concrete. Use approved supports to hold the reinforcement approximately equidistant from the top and bottom surface of the slab. Adjust reinforcement during concrete placement to maintain correct position. Sprinkle or sprinkle and consolidate the subgrade before the concrete is placed as directed. All surfaces must be moist when concrete is placed. Compact and shape the concrete once it has been placed to conform to the dimensions shown on the plans . Finish the surface with a wood float after it has set sufficiently to avoid slumping to secure a smooth surface or broom finish as approved. Cure the riprap immediately after the finishing operation in accord ance with Item 420.

3.2 Stone Riprap.

Provide the following types of stone riprap w hen shown on the plans .  Dry Riprap . Stone riprap with voids filled with only spalls or small stones.  Grouted Riprap. Type R, F, or Common stone riprap with voids grouted after all the stones are in place.  Mortared Riprap. Type F stone riprap laid and mortared as each stone is placed. Use spalls and small stones lighter than 25 lb. to fill open joints and voids in stone riprap, and place to a tight fit. Place mortar or grout only when the air temperature is above 35°F. Protect work from rapid drying for at least 3 days after placement . For slope or wave protection, if filter fabric is required, place filter fabric with its long axis running up and down the slope unless otherwise approved. For stream bank protection, if filter fabric is required, place the filter fabric with its long axis parallel to the centerline of the channel unless otherwise approved. Overlap the uphill or upstream sheet over the downhill or downstream sheet. For above water applications, ensure 608 adjacent sheets of filter fabric have a min imum overlap of 2 ft. in each direction. Secure filter fabric in place with nails or pins. Use 12- in. long, 3/16- in. diameter nails with 1.5 -in. washers, or U-shaped steel pins with each leg at least 9 in. long. Space nails or pins at a maximum of 10 ft. in each direction and 5 ft. along the seams. Along the seams, place nails or pins through both strips of filter fabric at approximately the midpoint of the overlap. Place additional nails or pins as necessary to hold the filter fabric in position. Alternati ve anchorage and spacing may be used when approved. Keep the fabric material free of tension, stress, folds, wrinkles, or creases. Methods for underwater filter placement must be approved before installation. For underwater placement, filter fabric should be unrolled in the direction of flow, overlapped at least 3 ft., and secured with sandbags, rocks, nails, or pins to prevent distortion. To prevent segregation and transport, underwater installation of a granular filter must be by clamshell bucket or tremi e, with the granular material released on or very near the bed, unless otherwise approved. Underwater placement of a granular filter is permitted only if the water velocity is less than 5 ft. per second unless otherwise approved. Any defects, tears, holes, flaws, or damage to filter fabric may be cause for rejection. Repair torn or punctured filter fabric by placing an additional layer of filter fabric over the damaged area, ensuring a minimum overlap of 3 ft. beyond the damaged area in all directions, and securing the filter fabric in place with pins or nails. Store filter fabric out of direct sunlight and cover the filter fabric as soon as possible after placement, but within 3 days.

3.2.1 Type R . Construct riprap as shown in Figure 1 on the Stone Riprap Standar d and as shown on the plans.

Place stones in a single layer with close joints so most of their weight is carried by the earth and not the adjacent stones. Place the upright axis of the stones at an angle of approximately 90° to the embankment slope. Place each course from the bottom of the embankment upward with the larger stones in the lower courses. Fill open joints between stones with spalls. Place stones to create a uniform finished top surface. Do not exceed a 6- in. variation between the tops of adjacent stones. Replace, embed deeper, or chip away stones that project more than the allowable amount above the finished surface. Prevent earth, sand, or foreign material from filling the spaces between the stones when the plans require Type R stone riprap to be grouted. Wet the stones thoroughly after they are in place, fill the spaces between the stones with grout, and pack. Sweep the surface of the riprap using a stiff broom after grouting.

3.2.2 Type F .

3.2.2.1. Dry Placement . Construct riprap as shown in Figure 2 on the Stone Riprap Standard. Set the flat surface on a prepared horizontal earth bed and overlap the underlying course to secure a lapped surface. Place the large stones first, roughly arranged in close contact. Fil l the spaces between the large stones with suitably sized stones placed to leave the surface evenly stepped and conforming to the contour required. Place stone to drain water down the face of the slope. 3.2.2.2. Grouting. Construct riprap as shown in Figure 3 on the Stone Riprap Standard. Size, shape, and lay large flat-surfaced stones to produce an even surface with minimal voids. Place stones with the flat surface facing upward parallel to the slope. Place the largest stones near the base of the slope. Fill spaces between the larger stones with stones of suitable size, leaving the surface smooth, tight, and conforming to the contour required. Place the stones to create a plane surface with a variation no more than 6 in. in 10 ft. from true plane. Provide the same degree of accuracy for warped and curved surfaces. Prevent earth, sand, or foreign material from filling the spaces between the stones. Wet the stones thoroughly after they are in place, fill the spaces between them with grout, and pack. Sweep the surface u sing a stiff broom after grouting. 3.2.2.3. Mortaring . Construct riprap as shown in Figure 2 on the Stone Riprap Standard. Lap courses as described for dry placement. Wet the stones thoroughly before placing mortar. Bed the larger stones in fresh mortar as they are being placed and shove adjacent stones into contact with one another. Spread excess mortar forced out during placement of the stones uniformly over them to fill all voids completely. Point up all joints roughly either with flush joints or shallow, smooth- raked joints as directed. 609 3.2.3. Common. Construct riprap as shown in Figure 4 on the Stone Riprap Standard. Place stones on a bed excavated for the base course. Bed the base course of stone well into the ground with the edges in contact. Bed and place each succeeding course in even contact with the preceding course. Use spalls and small stones to fill any open joints and voids in the riprap. Ensure the finished surface presents an even, tight surface, true to the line and grades of the typical sections. Prevent earth, sand, or foreign material from filling the spaces between the stones when the plans require grouting common stone riprap. Wet the stones thoroughly after they are in place, fill the spaces between them with grout , and pack. Sweep the surface using a stiff broom after grouting.

3.2.4 Protection . Construct riprap as shown in Figure 5 on the Stone Riprap Standard. Place riprap stone on the

slopes within the limits shown on the plans. Place stone for riprap on the filter fabric to produce a reasonably well-graded mass of riprap with the minimum practicable percentage of voids. Place riprap stone on top of the filter fabric, always starting at the bottom and working toward the top of any slope. Construct the riprap to the lines and grades shown on the plans or staked in the field. A tolerance of +6 in. and -0 in. from the slope line and grades shown on the plans is allowed in the finished surface of the riprap. Place riprap to its full thickness in a single operation. Avoid displacing the filter fabric. Ensure the entire mass of stones in its final position is free of objectionable pockets of small stones and clusters of larger stones. Do not place riprap in layers, and do not place it by dumping it into chutes, dumping it from the top of the slope, pushing it from the top of the slope, or any method likely to cause segregation of the various sizes. Obtain the desired distribution of the various sizes of stones throughout the mass by selective loading of material at the quarry or other source, or by other approved methods of placement that will produce the specified results. Rearrange individual stones using mechanical equipment or by hand if necessary to obtain a reasonably well-graded distribution of stone sizes. If required, use the bedding thickness shown on the plans and place stone for riprap on the bedding material to produce a reasonably well -graded mass of riprap with the minimum practicable percentage of voids.

3.3 Pneumatically Placed Concrete Riprap, Class II . Meet the requirements of Item 431. Provide

reinforcement as shown on the plans and in accordance with Item 440. Support reinforcement with approved supports throughout placement of concrete. Give the surface a wood- float finish or a gun finish as directed. Cure the riprap with membrane- curing compound immediately after the finishing operation in accordance with Item 420.

3.4 Cement -Stabilized Riprap . Follow the requirements of the plans and the provisions for concrete riprap

except when reinforcement is not required. The Engineer will approve the design and mixing of the cement - stabilized riprap.

3.5 Special Riprap . Construct special riprap as shown on the plans.