PRE-CRACKING AS A TECHNIQUE TO MINIMISE REFLECTION CRACKING IN SEMI-RIGID PAVEMENT STRUCTURES - LONG TERM PERFORMANCE MONITORING

摘要

In the UK, an extensive research programme has been undertaken investigate the benefits or otherwise of pre-cracking semi-rigid pavements to minimise reflection cracking. Transverse pre-cracks in the cement bound base layer are intended to reduce thermal movements in the base layer and hence minimise reflection cracking. As a consequence pavement life is extended with reduced maintenance intervention requirements and thinner asphalt surfacing. Ultimately semi-rigid pavement construction becomes more financially competitive due to savings in the whole life cost of the pavement. Twelve sections incorporating pre-cracked cement-bound bases were constructed as full-scale trials in 1996. The sections were at four separate locations in the UK and j included 8 experimental and 4 control sections. The sections have been monitored since j construction between 1996 and 2002. This paper presents the sites and the in-service performance data collected that assesses the initiation and growth of reflection cracks in trial and corresponding control sections. The experiments have been successful and in the UK and have led to revised specification clauses and design standards, including compulsory pre-cracking for some semi-rigid pavements and reductions in the thickness of the asphalt surfacing.