Top-Down Cracking in Asphalt Pavements: Causes, Effects, and Cures

Heterogeneity effect on fracture parameters of a multilayer asphalt pavement structure containing a top‐down crack and subjected to moving traffic loading

“…Two types of cracks (i.e., top‐down cracks [TDCs] and bottom‐up cracks [BUCs]) are often created in the asphalt pavements. The TDC starts from the surface of the pavement and propagate downwards to the lower layers 1–3 . The creation of TDCs is mostly due to the changes in the temperature and weather conditions, but the further propagation of these cracks occurs mainly because of the loading of passing vehicles.…”

Evaluation of the Impact of Asphalt Mix Segregation on Pavement Performance

“…The Asphalt Institute reported that, based on its DAMA modeling program, the presence of different levels of segregation (i.e., low, medium, and high) in wearing course reduced pavement fatigue life by 38%, 81%, and 99% respectively ( 1 ). Other studies indicated that segregated areas can potentially exhibit early top-down cracking in the longitudinal direction ( 3 , 4 ). In addition, significant reflective cracks were also observed on the segregated areas where non-uniform mix temperatures were recorded at the time of paving ( 5 ).…”

Causes, mechanisms, and remedies of top-down cracking of asphalt pavements : state-of-the-art

“…In some cases, TDC has even been the predominant type of deterioration mode of the pavements. Filed investigation on 13,612 km in Colorado asphalt pavement reported that 42 percent of the pavement was in poor condition, cracking was assigned the responsible factor, and Top-down cracking was considered a significant portion of this distress (Harmelink et al, 2008). Also 90 percent of asphalt pavements that are scheduled for rehabilitation in Florida are due to TDC (Myers et al, 1998).…”

“…Top down cracks is an observable fact for the last two decades, which have attracted the concerns of many pavement engineers and highway departments; this type of cracks is prevalent in asphalt pavements and mostly occurs within the wearing course of the AC (Lippert, 2001;Harmelink et al, 2008;Molenaar's, 1984). It was documented by Myers et al, (2001) that top-down cracks could also exhibited in two forms, the block cracking which is distributed irregularly on the surface and is attributed to the age of the mixture.…”

“…Kennedy et al, concluded that a good determination to the asphalt binder content and the best selection of the aggregate size and gradation have a significant effect in controlling the amount of segregation that could occur to the asphalt pavement structure. Superpave mix was also recommended by Harmelink et al, (2008) where they explained that increasing the asphalt cement content in the mix could reduce the occurrence of segregation and consequently the possibility of the propagation of TDCs. One of the suggested remedies to the cracks which appear in segregated areas is to apply sealing 90 along the crack in its early stage, and before the cracks propagate into wider cracks, Harmelink et al, (2008).…”