Gradation scope of Superpave

Based on the maximal density graph theory, Marshall experiments were done with crushed stone when the values of n equal to 0.35, 0.40, 0.45, 0.50 and 0.55. The values of n were ascertained when the asphalt mix density was maximal.After a series of calculation and taking the Superpave's regulations about restricted zone and control points and the wave range of each sieve in engineering experience into account, the gradation scopes of super-layer, mid-layer and under- layer were put forward. The mix manufactured within these gradation scopes is proved having scarf joint-compact state to both reduce penetration, and have good anti-rutting performance by engineering experience and Bailey's method.