Attachment 1 - CDOT Riprap Salient Characteristics.pdf

This document specifies riprap material requirements for road and bridge construction projects under Colorado Department of Transportation (CDOT) standards. The specifications reference Section 506 of the Standard Specifications for Road and Bridge Construction and require compliance with ASTM C127 (Standard Test Method for Relative Density and Absorption of Coarse Aggregate) and ASTM C535 (Standard Test Method for Resistance to Degradation of Large-Size Coarse Aggregate by Abrasion and Impact).

Riprap material must exhibit the following salient characteristics: hard, durable, angular rock that is weathering resistant with a minimum specific gravity of 2.5 and free of organic matter, soil, or soft shale. For d50 size 6 inch riprap gradation, the material must meet specified distribution requirements: 70-100 percent smaller than 12-inch stones (weighing approximately 85 pounds), 50-70 percent smaller than 9-inch stones (approximately 35 pounds), 35-50 percent smaller than 6-inch stones (approximately 10 pounds), and 2-10 percent smaller than 2-inch stones (approximately 0.4 pounds). These gradation and physical property requirements ensure the riprap will perform effectively in road and bridge construction applications requiring erosion control and structural stability.