A review on crack relief layer (CRL) in roads and highways

Roads and highways are the most important mode of transportation systems for development of a nation. in order to fulfil this purpose,the pavement must be able to provide a safe and comfortable riding surface for the road users. however,pavement deterioration is a major obstacle that can prevent pavement from serving its main purposes. the most common type of pavement deterioration is reflective cracking which occurs when a crack in an overlay layer reflect the pattern of cracks and joints of the old pavement underneath it. crack relief layer (crl) is a layer that is placed between the new overlay and the old pavement in order to dissipate pavement movements before they create stress in a new overlay surface. crl is an open-graded mix that had around 20 to 35% of air void which act as a cushion layer in order to dissipate cracks development in pavement layer. it has low bitumen content that normally around 3% in order for it to act as a semi-unbound layer in order to prevent horizontal and vertical movement of pavement strata. previous implementation of crl in airport and runways shows that crl performance is promising for it to be used in roads and highways in order to overcome pavement distress. further research is needed in order to ensure crl implementation in pavements industry. © 2016 penerbit utm press. all rights reserved.