Aggregate Baserock Primer

Aggregate Baserock is a dense graded blend of coarse and fine aggregate which when properly placed and compacted provide a stable and durable base allowing further construction.

Aggregate Baserock Should Demonstrate:

  • Stability: Resist deformation when under load (after proper placement and compaction).
  • Durability: Resist degradation due to use (after proper placement and compaction).
  • Easy to Place & Compact: Product is workable and predictable.
  • Consistency: Product is the same load after load.
  • Meets Specification: No rejections due to inferior material.
  • Availability: Product is locally available when needed.
  • Versatility: Can be used in a variety of applications.

The National Stone Association (NSA) recommends that Baserock consist of 100% crushed, angular particles. “Particle shape and surface texture are important in providing a stable base course. Angular, nearly equidimensional particles having a rough surface texture are preferred over round, smooth particles. Angularity contributes to aggregate interlock, and a rough surface texture inhibits movement of one particle relative to another.” The NSA further states that, “Where high stability is required, rounded aggregate should be avoided because of its tendency to shift (move) under applied traffic loadings.”

Most Public Agencies in Central California specify Baserock meet Caltrans Standards. Section 25 and 26 of the Caltrans Standard Specifications address subbase and base materials. Caltrans standards set limits for Aggregate Gradation, R-Value, Sand Equivalent, and Durability Index. Suitable base materials demonstrate test results that consistently meet these standards.

Caltrans identifies five different Subbase types (Class 1 thru Class 5) in Section 25 and three different Aggregate Base types (¾″ & 1 ½″ Class 2, Class 3) in Section 26. Each of these materials is differentiated by variations of Gradation, R-Value, and Sand Equivalent. Please keep in mind that material specifications can be modified in the Project Special Provisions Documents.

Some agencies refer to the Standard Specifications for Public Works Construction or “Green Book”developed jointly by the Southern California Chapter of the American Public Works Assn. and the AGC. This specification classifies base materials as Crushed Aggregate Base, Crushed Miscellaneous Base,Processed Miscellaneous Base or Select Subbase. Standards are set for Gradation, R-Value, Sand Equivalent, and Durability Index as with Caltrans but also Specific Gravity, and Percentage of Wear (LA Rattler). This specification was developed to address some marginal materials available in the Southern California area.

  • Make certain of the Product RequiredProject Service Requirements (Heavy or Light Use)
  • Product Name
  • Product Maximum Particle Size (1 ½″ or ¾″)
  • Specifying Agency (Caltrans, Green Book, or Other)
  • Special Provisions addressing additional Baserock specifications
  • Certification Required (Submittals) (Forward Information to Supplier)
  • Quantity Required (Specific Gravity—Conversion Tons to Cubic Yards)
  • Product Availability (Available when required, can handle Daily Shipping Requirements)
  • Technical Support Required (Lab Work)
  • The Reputation of your Supplier and their Products & Services

  • 100% Crushed Granite (Provides Superior Stability and Durability)
  • Many different Baserock types available:Class 2 Base (1 ½″ & ¾″) (Crushed Miscellaneous Base)
  • Class 3 Base (1 ½″ & ¾″)
  • Class 4 Base (1 ½″ & ¾″)
  • Aggregate Subbase (1 ½″ & ¾″) (Caltrans Class 1 thru 3)
  • FAA Aggregate Base
  • 10″ Engineered Base
  • High R-Value & Sand Equivalent demonstrates the low clay content (Provides Improved Consistency & Predictability)
  • Low Clay Content provides for greater performance and workability in high moisture situations.
  • High Daily Production and Shipping Capacity (Can Handle Large & Small Jobs)
  • Class 2 and Class 3 Products are available 24 hours/day, 7 days/week thru GraniteXpress Loadout.(Provides improved Jobsite Flexibility)
  • Graniterock can provide delivery to your jobsite if desired. (One call ordering and delivery)
  • GraniteXpress loading capability minimizes product segregation. (Provides improved Product Quality, Consistency, Predictability, and Acceptance)
  • Technical Support available for assistance.
  • At present, Graniterock is the only supplier to use Statistical Process Control (SPC) to control the production process.
  • Proven Product Track Record (Aggregate is widely accepted and approved)
  • Wilson Quarry Products are recognized as the Industry Standard in the Monterey Bay Area
  • Qualification Testing procedure minimized
  • Graniterock has a 100 year history of providing high quality products and service.

For more information regarding Aggregate Baserock and other Construction Aggregates, please contact the Wilson Quarry Sales Office at 831.768.2380.