CAUSES OF INTERMEDIATE ASPHALT CONCRETE LAYER FAILURE

Abstract

This study examines the causes of damage in the intermediate asphalt concrete layer located between a porous base and the upper stone mastic asphalt layer. The main damage mechanism was found to be moisture penetration into the intermediate layer, followed by heating during the summer, leading to bitumen leaching and the disintegration of the mix into separate particles. Analysis of the gradation and binder content showed that current standards limit the ability to increase the thickness of the bitumen film, which is necessary to improve material durability. To prevent such damage, it is proposed to replace the upper layer with dense fine-grained asphalt concrete, increase binder application in the underlying layer, and revise standards for bitumen content, water absorption, and residual air voids during mix design. These recommendations aim to enhance the water resistance and durability of asphalt concrete while maintaining its economic attractiveness in regions with limited supplies of high-strength aggregate.