The crushing value of coarse aggregates is a critical parameter in evaluating the strength and durability of construction materials used in highway and pavement engineering. In the context of transportation infrastructure, the American Association of State Highway and Transportation Officials (AASHTO) provides standardized testing procedures to assess the quality of aggregates. One such test is the AASHTO T 283, “Resistance of Compacted Bituminous Mixtures to Moisture-Induced Damage,” which indirectly relates to aggregate strength, but for direct assessment of aggregate crushing resistance, AASHTO relies on methods aligned with ASTM standards.
The most relevant test for determining the crushing value of coarse aggregates is AASHTO T 277, “Specific Gravity and Absorption of Fine and Coarse Aggregates,” which supports calculations needed for mix design but does not directly measure crushing strength. However, the actual test commonly used to evaluate the resistance of coarse aggregates to crushing under gradually applied compressive load is ASTM C131/C131M, “Resistance to Degradation of Small-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine,” which is often referenced or adapted by state DOTs under AASHTO guidelines.
In practice, many state departments of transportation use a combination of AASHTO and ASTM standards. For instance, while AASHTO does not have a standalone test titled “Crushing Value,” it adopts ASTM C535, “Resistance to Degradation of Large-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine,” for larger aggregates (greater than 19 mm). These tests measure degradation rather than pure crushing but are strong indicators of aggregate toughness..jpg)
Another closely related method is the Aggregate Crushing Value (ACV) test described in British Standard BS 812-110. Although not part of AASHTO’s official suite, some U.S. agencies reference similar principles when evaluating aggregate performance under load. However, within the AASHTO framework, compressive strength characteristics are typically inferred through performance-based tests such as resilient modulus or indirect tensile strength in asphalt mixtures rather than isolated aggregate crushing values.
The absence of a direct “crushing value” test in AASHTO stems from its performance-oriented approach. Instead of focusing solely on individual aggregate properties, AASHTO emphasizes how aggregates behave within mixtures under real-world conditions. For example, AASHTO M 323 outlines gradation requirements for aggregates used in asphalt mixtures, ensuring that particle shape, texture, and strength contribute collectively to mixture stability..jpg)
Moreover, supplementary tests like AASHTO T 324 (Overlay Tester) or T 322 (Determining Dynamic Modulus) assess mixture response where aggregate quality plays a significant role. The selection criteria for coarse aggregates often include limits on Los Angeles abrasion loss—typically not exceeding 40% for surface courses—as specified in AASHTO M 323 or individual state specifications derived from it.
In summary, while there is no specific AASHTO test designated as “crushing value” for coarse aggregates analogous to certain international standards, the mechanical durability and resistance to degradation are evaluated through standardized methods such as ASTM C131 and C535 adopted within AASHTO guidelines. These assessments ensure that coarse aggregates used in highway construction possess sufficient toughness to withstand traffic loads and environmental stresses over time. Engineering decisions rely on these test results combined with mixture-level evaluations to guarantee long-term pavement performance.