Streetworks

Flexible Carriageway Faults, Defects and Possible Causes in Surfacing Materials

Defect	Possible Cause
Bleeding	Too much bitumen in the mix
Brown appearance	Not enough bitumen in the mix. Too much moisture in the mix. Too hot or burnt.
Rich fatty spots	Too much bitumen in the mix
Poor surface texture	Too many fines in the mix Too much bitumen in the mix Laying too cold Poor laying and rolling operation Over Rolling Rolling when mix is too hot Rolling when mix is too cold
Rough surface	Too many fines in the mix Mix too hot for rolling Poor laying and rolling operations Leaving roller standing on hot surface Roller too heavy for material type and layer thickness
Honeycomb appearance	Course mix used Too many fines in the mix Too hot or cold to lay and compact Poor rolling operation
Ravelling	Course mix used Too many fines in the mix Mix too cold to lay and compact
Roller marks	Too many fines in the mix Too much bitumen in the mix Roller too heavy for the material type and layer thickness Poor rolling operation Rolling when the material is too hot or cold
Waving	Too many fines in the mix Too much bitumen in the mix Moisture in the mix Poor rolling operation Mix too hot for rolling Roller too heavy Mix laid too thick Opened to traffic too early
Fine cracks Crazing	Not enough bitumen in the mix Too many fines in the mix Over rolling Rolling when too hot Roller too heavy
Large cracks Crazing	Mix too hot to roll Over rolling Roller too heavy
Breakdown of aggregate during rolling operation	Mix too course Mix too hot or cold for rolling Poor rolling operation Roller too heavy
Surface tears	Not enough bitumen in the mix Mix too course Mix too hot or cold for laying and rolling
Movement of surfacing layer on the base	Too much bitumen in the mix Excessive moisture in the mix Mix too hot or cold for laying and compacting Roller too heavy Too much tack coat used
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