1. RIPRAP INSTALLATION Dennis Clute Construction Engineer NDCSMC Clute

2. CONSTRUCTION SPECIFICATIONS
CS 21 – Excavation
CS 23 – Earthfill
CS 24 – Drainfill
CS 31 – Concrete for Major Structures
CS 32 – Structure Concrete
CS 61 - Rock Riprap
CS 62 - Grouted Rock Riprap
CS 95 - Geotextile
Construction

3. STEP BY STEP PROCESS Materials Approval Staking Subgrade Preparation
Filter, Bedding, or Geotextile
Placement
Grouting (where applicable)
Construction

4. ROCK MATERIALS APPROVAL
Construction Specifications 61 and 62 require the contractor to designate the rock source at least 30 days prior to delivery to the site.
When possible the engineer should visit the source before approving the rock.
Construction

5. LIST OF MATERIALS Imported fill material where applicable
Filter, bedding, or geotextile
Rock
Grout design and materials where applicable
Construction

6. MATERIALS APPROVAL
The engineer should notify the inspector once the materials are approved for use.
The job diary has a section entitled “Material Certification Record”. Record in this section the date of approval and the date of material delivery.
Construction

7. MATERIALS APPROVAL Quality Gradation Shape Bulk Specific Gravity
Absorption
Soundness
Gradation
Construction

8. MATERIALS APPROVAL Quality Not This Shape
Shall be angular to sub-rounded.
The least dimension of individual rock shall not be less than 1/3 the greatest dimension. D
Not This
This
> 1/3 D
Construction

9. MATERIALS APPROVAL Quality 2.5 X 62.4 lb/cu. ft. = 156 lb/cu. ft.
Shape
Bulk Specific Gravity is the ratio of the unit weight of a material to the unit weight of water. Rock with a specific gravity of 2.5 would have a unit weight of
2.5 X 62.4 lb/cu. ft. = 156 lb/cu. ft.
Construction

10. MATERIALS APPROVAL Quality Shape Bulk Specific Gravity
Absorption - A dry rock weights 150 pounds. The rock is soaked in water for days, the surface is dried and the rock now weighs 153 pounds. The absorption is computed as follows:
(( ) / 150) x 100% = 2%.
Construction

11. MATERIALS APPROVAL Quality Shape Bulk Specific Gravity Absorption
Soundness - Rock shall be tested for soundness according to ASTM Method C88. ASTM Method C88 is a method that simulates freeze thaw damage.
Construction

12. MATERIALS APPROVAL
Quality
Construction

13. MATERIALS APPROVAL Quality
Shape
Bulk Specific Gravity
Absorption
Soundness
Gradation is generally specified by weight but can be specified by dimension.
Construction

14. EXAMPLE GRADATION Particle % Finer Mass (lb.) Than 300 100
to 100
to 50
to 15
Construction

15. GRADATION Rock that is too large will cause quantity overruns.
Planned limits
Rock that is too large will cause quantity overruns.
Rock that is too small may become displaced.
flow
Rock that is poorly graded may not protect the subgrade as intended.
Exposed subgrade
Construction

16. GRADATION
ASTM D Standard Practice for Specifying Standard Sizes of Stone for Erosion Control
ASTM D Standard Test Method for Particle Size Analysis of Natural and Man-Made Riprap Materials
Construction

17. ASTM D 6092 - Standard Practice for Specifying Standard Sizes of Stone for Erosion Control
The standard sizes for rock are:
Rock
R-20
R-60
R-150
Avg. lbs. 20 60
150
R-300
R-700
R-1500
300
700
1500
Construction

18. ASTM D 6092 - Standard Practice for Specifying Standard Sizes of Stone for Erosion Control
This standard also addresses filter stone to be used for bedding the rock. The standard sizes for filter stone are:
Filter Stone
FS-1
FS-2
FS-3
Size Range
#100 to 3/8”
#100 to 2”
#16 to 6 1/2”
Construction

19. STAKING Survey rod Record station number, H, and D on lathe near hub.
Set hubs away from the immediate work area. D
Construction

20. STAKING/JOB DIARY
The job diary is not to be used for recording survey notes, however, you should record information about staking.
Record a detail of exactly what was staked, when, and by whom.
This could be especially important if the NRCS is the party responsible for staking.
Construction

21. SUBGRADE PREPARATION
Surface irregularities, loose material, vegetation, and all foreign matter shall be removed from foundations.
Riprap and bedding or geotextiles shall not be placed until the foundation preparation is completed, and the subgrade surfaces have been inspected and approved by the Engineer.
The surface of the finished material shall be to grade and free of mounds, dips or windrows.
Construction

22. LACK OF SUBGRADE PREPARATION
Construction

23. COMPACTION OF SUBGRADE
Record results of tests for earthfill placement moisture and density in the job diary.
Hardhats?
Construction

24. FILTERS, BEDDING, OR GEOTEXTILE
Filters are required where riprap alone will not protect against base soil erosion. These filters will likely be two stage filters in order to safely transition from the small base soil particles to the rock riprap.
Base
Soil
Sand
Gravel
Riprap
Construction

25. FILTERS, BEDDING, OR GEOTEXTILE
Geotextile is often used to filter base soil.
There is a potential for plugging of the geotextile in some cases.
Filter compatibility may be important.
Direction of lap splice is critical.
Base
Soil
Geotextile
Water
Construction

26. PLACEMENT Equipment-Placed Hand-Placed
Install full course thickness in one operation.
Should result in reasonably homogeneous rock fill with large rocks evenly distributed and small rocks filling voids between large rocks.
Hand-Placed
Large rocks should be firmly in contact with one another.
Spaces between large rocks filled with small rocks.
Slab rock laid on vertical edge.
Construction

27. SECTION VIEW of PROPER vs. IMPROPER PLACEMENT
Large rocks evenly distributed and small rocks filling voids between large rocks.
IMPROPER PLACEMENT
Large rocks distributed unevenly with pockets of small rock in between.
Construction

28. PLAN VIEW OF PROPER PLACEMENT
You want the the large rocks touching, the small rocks filling the voids between the large rocks. You shouldn’t see much ground when you look down through the rocks.
Construction

29. AVOID DOUBLE DECKING
Double decking usually occurs when hand placing is involved. It is where smaller rocks are placed on top of the rock fill to bring it up to the specified grade. Looks good, works bad.
Construction
Clute

30. GROUTED ROCK RIPRAP
Grouted rock riprap is often used if larger rock is not economically available and heavy-duty protection is needed.
Sometimes it is designed with oversize rocks placed in a variable pattern to produce a rough surface that will retard the water velocity or wave runup in a protected area.
Normally the grout should not be so deep that the mass will not crack to allow the riprap to maintain contact with the subgrade if settlement occurs.
Construction

31. GROUT PLACEMENT Good grout placement begins with good rock placement.
Ideal grout placement would bind the individual rocks together but would leave the rock exposed for energy dissipation. We are not trying to pour a concrete slab here, we still want the riprap to be able to move some so that it can continue to conform to the subgrade should subgrade settlement occur.
Poor grout placement
Construction

32. GROUT QUANTITY
Expect the grout quantity to be 0.25 to 0.35 times the volume of rock.
Quantity of grout is dependent on the gradation and size of the rock and the grout depth.
Well graded rock – less voids -less grout
Gap graded rock – more voids - more grout
Construction

33. PLACING Grout mix shall not be dropped over 5 feet.
Grout shall not be placed until the rock riprap has been inspected and approved.
Rock shall be kept wet for at least 2 hours immediately prior to grouting.
Rock shall be washed with water to remove fines prior to placing grout.
Rock shall be kept moist just ahead of grouting.
Construction

34. PLACING
Grout placed on nearly level areas may be placed in one course.
On slopes, grout shall be placed in two courses approximately 10 feet wide starting at the toe and working upward.
Grout shall be discharged directly to the rock surface using a splash guard to guard against displacing rock.
Bars and concrete vibrators shall be used to loosen tight pockets of rock and aid grout penetration.
Construction

35. PLACING Brooming shall be uphill.
After grout has stiffened the entire surface shall be rebroomed to eliminate runs and fill voids caused by sloughing.
Curing shall begin immediately. A strip or panel is considered complete only after curing has begun.
After completion of any strip or panel, no workman or load shall be allowed on the grouted surface for 24 hours.
Construction

36. CURING
The surface shall be kept moist for 7 days or until approved curing compound is applied.
On large jobs this means start the wetting or apply the curing compound before all the grout is placed.
Spray curing compound on the moist surface as soon as free water disappears.
Do not spray areas requiring bond to subsequently placed grout or concrete.
Construction

37. INSPECTION CHECKLIST Check materials against approval documentation.
rock riprap
bedding material and/or geotextile
grout design
curing compound
Check assembly and installation.
subgrade compacted to line and grade
bedding or geotextile properly installed
geotextile not punctured
in-place rock gradation as specified
approved grout mix supplied including air content and temperature of grout
grout installed to specified limits without segregation
proper grout curing
Construction

38. JOB DIARY Record material certification for:
rock riprap
grout design
bedding material and/or geotextile
curing compound
Record time of delivery and status of materials.
Record results of tests for earthfill placement moisture and density, gradation tests on bedding, filter, and/or rock riprap, air content and temperature of grout.
Record interim, cumulative, and final quantities on a daily basis.
Record day to day activities relating to the installation of rock riprap and/or grouted rock riprap.
Construction