Part 1 — General
1.1 Section Includes
A.Loose and compacted riprap.
1.2 Related Sections
A.Section 02075: Geotextiles
B.Section 02317: Structural Excavation
1.3 References
A.AASHTO T 85: Specific Gravity and Absorption of Coarse Aggregate
B.AASHTO T 96: Resistance to Degradation of Small -Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine
C.AASHTO T 104: Soundness of Aggregate by Use of Sodium Sulfate or Magnesium Sulfate
1.4 Definitions
A.D 50 - The median rock diameter wi thin a riprap mass for which 50 percent of the roc ks are smaller and 50 percent are larger.
B.Rock diameter - The equivalent diameter (average width) of a given rock.
1.5 Submittals
A.The rock source, gradation, and laboratory values for the properties in Table 1 , for information .
Part 2 — Products
2.1 Riprap
A.Rock
1.Angular, hard , durable , resistant to weathering and free from seams, cracks and other structural defects .
a.Do not use shale, mudstone, or other rock that may break into smaller pieces in the process of handling and placing.
b.Do not use concrete or asphalt rubble.
2.Meet the properties listed in Table 1. Table 1 Physical Properties Property Value Test Method Specific Gravity 2.5 min AASHTO T 85 Absorption 2% max AASHTO T 85 Soundness of Aggregate using Sodium Sulfate or Magnesium Sulfate 12% max or 17.5% max AASHTO T 104 Resistance to Degradation 40% max AASHTO T 96
3.Well graded rock throughout the riprap layer to produce a dense mass. Refer to Table 2 for riprap gradation limits .
a.Control gradation by sample measurement or by visual inspection, as determined by the Engineer. Table 2 Riprap Gradation Limits Rock Diameter Range (ft) Percent of Gradation Smaller Than 1.5D 50 to 1.7D 50 100 1.2D 50 to 1.4D 50 85 1.0D 50 to 1.15D 50 50 0.4D 50 to 0.6D 50 15 0.1D 50 10
2.2 Erosion Control Geotextile
A.Refer to Section 02075, except use a nonwoven 12 oz/yd2 minimum average roll value.
Part 3 — Execution
3.1 Preparation
A.Excavate and grade to provide a firm and uniform bearing surface. Refer to Section 02317.
B.Install erosion control geotextile as shown.
3.2 Loose Riprap
A.Place rocks to provide a secure unsegregated dense mass.
1.Distribute and manipulate the rocks so that the larger rock s are uniformly distributed and the smaller rock s serve to fill the spaces between the larger rocks .
3.3 Compacted Riprap
A.Place rocks conforming to this Section, A rticle 3.2.
B.Compact riprap to remove irregular surface protrusions larger than 3 inches.
Source: Utah Standard Specifications for Road and Bridge Construction, 2026 Edition. Pages 313–315 of 1,331.