Section_31_37_00_Riprap.pdf

SECTION 31.37.00

RIPRAP

PART 1 - GENERAL

1.1 REFERENCE STANDARDS

A. ASTM International

(1) ASTM C128-12 Standard Test Method for Density, Relative Density (Specific Gravity), and Absorption of Fine Aggregates

(2) ASTM C131-06 Standard Test Method for Resistance to Degradation of Small-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine

B. American Association of State Highway and Transportation Officials (AASHTO)

(1) AASHTO M288-06 Geotextile Specifications

C. New Mexico Department of Transportation (NMDOT)

(1) Standard Specifications for Highway and Bridge Construction (2014 edition)

(2) Standard Drawings

1.2 GENERAL

The work covered by this specification consists of furnishing all labor, equipment, materials, and all efforts necessary to construct riprap protection in the areas specified. Provide riprap with at least 80% of the stones meeting the specified size requirements. Use stones less than the minimum dimensions to fill voids.

PART 2 - MATERIALS & EQUIPMENT

2.1 MATERIALS

A. Provide rock for riprap, gabions and rock faces in accordance with NMDOT standard specification section 602.

B. Provide rocks or rough quarry stone with no more than 60% wear, in accordance with AASHTO T96. Provide stone with a soundness loss of no more than 21, in accordance with AASHTO T104 using magnesium sulfate solution with a five cycle test duration.

C. The contractor shall provide the rock to the gradation requirements of Table 4. Both the width and the thickness of each piece of riprap must be at least 1/3 of the length.

D. Provide submittals of materials prior to installation.

Table 4 - In-Place Protection Riprap Gradation Requirements Nominal

Thickness of Riprap

(in)

Maximum Rock Size

(lb)

Maximum Rock Size

(in)

60% to 70% by Weight1

30% to 40% by Weight1

0 to 10% by Weight Shall be

Less than2 (lb)

From (lb)

To (lb)

From (lb)

To (lb)

500 20

1,250

1,250

4,500

2,250

2,250

4,500

1 Sand and rock dust shall be less than five percent (5%) by weight of total riprap material.

2 The percentage of this size material shall not exceed an amount which will fill the voids in larger rock.

E. Provide geotextile (filter fabric) n accordance with specification 31 32 19 Geotextiles, type 2 for protection of stone riprap.

PART 3 - CONSTRUCTION METHODS

3.1 RIPRAP

A. The contractor shall dress slopes and protected areas before the placement of riprap.

B. Place riprap to its full thickness in a single operation. Do not place riprap in layers and ensure that the entire mass of stones in their final position is free from objectionable pockets of small stones and clusters of larger stones.

C. Do not place riprap at the top of the levee slope and then push it down from the top of the slope, or use any method likely to cause segregation of the various sizes.

D. Place stone for riprap on the bedding material to produce a reasonably well-graded mass of riprap with the minimum practicable percentage of voids.

E. Obtain the desired distribution of the various sizes of stones throughout the mass. Rearrange individual stones by mechanical equipment or by hand if necessary to obtain a reasonably well-graded distribution of stone sizes. Use spalls and small stones lighter than twenty five

(25) pounds to fill open joints and voids in stone riprap, and place to a tight fit.

F. A tolerance of plus six inches (+6 in) and minus zero inches (-0 in) from the slope grade is allowed in the finished surface of the riprap.

3.2 FILTER FABRIC

A. Seams shall be in accordance with the Construction/Installation Guideline Appendix to the AASHTO M 288 Specification.

(1) The fabric shall be laid out smooth without wrinkles or folds on the prepared subgrade in the direction of the construction traffic.

(2) Adjacent fabric rolls shall be overlapped a minimum of two (2) feet, and ends of rolls shall be overlapped three (3) feet.

(3) On curves, the fabric may be folded or cut to conform to the curves.

(4) The fold or overlap shall be upstream over downstream and upslope over downslope.

B. Damaged areas shall be repaired by overlaying the area with sufficient material to overlap on all edges by at least two (2) feet.

C. The rock riprap material shall be placed by end dumping onto the filter fabric from the edge without damage to the fabric. Manual labor may be required to correctly place rock to a finish level plane and cover voids. Construction equipment will not be allowed directly on the fabric.

(1) A minimum of twelve (12) inches of aggregate must be placed on the fabric prior to the movement of construction equipment and turning movements must be carefully monitored.

(2) Any ruts occurring during construction shall be filled with additional riprap and smoothed out.

(3) If placement of the backfill causes damage to the filter fabric, the damaged area shall be repaired as described above.

(4) Ensure that the finished riprap surface varies no more than three inches from the specified slope.

--End of Specification--