Impact of lowered laboratory compaction rate on strength properties of asphalt mixtures

Abstract

Highly important issue related to good pavement quality and job performance is in case of asphalt mixtures the compaction rate of asphalt layers. Compaction rate is a factor which has very significant impact on the durability, strength properties, resistance to cracking, etc., of asphalt pavements. Even though the compaction rate influences the lifespan of a pavement, it is very often neglected or the attention which is given to proper compaction is not sufficient enough. In this experimental study the asphalt mixture test specimens were compacted at different temperatures and using different compaction energies to evaluate the influence of poor compaction rate on the mixture properties. The chosen tested mixture was asphalt concrete for wearing courses with maximum particle size of 11 mm. The specimens were compacted on Marshall impact compactor by different amount of blows. The stiffness modulus at three, respectively, four testing temperatures was measured on all of the specimens. Additionally, some of the test specimens were exposed to artificial laboratory ageing to evaluate the effect of compaction rate to fatigue resistance of the mixture. The result shows very strong dependence between compaction rate and decrease of stiffness modulus.