Case Study 9 : Crocodile (Alligator) Cracking and depressions

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Fatigue cracking leads to major defects as the loose blocks of asphalt are removed by traffic creating missiles and potholes. By using a thin layer of fine grade Viafix a very long-term repair can be undertaken very quickly and cheaply without sawing or excavation. As Viafix can be trafficked during the curing process without rutting or sticking to tyres the action of passing vehicles helps compact the finer particles within the aggregate into the cracks, effectively ‘welding’ the loose blocks together. For depressions raking Viafix out to feather the edges of the defect leaves a flat running surface with good skid resistance  eliminating  the ‘thump’ from vehicles which previously exacerbated the problem. This repair was made to an area of crocodile cracking in a motorway maintenance depot (1). A wooden beam was placed across the surface of the defect to show the depression which had arisen (2). Once Viafix had been added and roughly raked in, compaction was successfully carried out by a works vehicle with no rutting or plucking out (3).