Equipment and construction sequence of surface dressing

The main equipment needed for surface dressing (chip seal) is as follows the distributor, the aggregate spreader, the roller(s) and cleaning equipment. 

The distributor is a truck- or trailer-mounted insulating tank that applies via a spray bar the binder material uniformly and in specified quantity (spread rate). Almost all distributors 

Calibration of the distributor before initiation of works must always be carried out to ensure quality work. The key factors to consider to achieve a uniform application of the required spread rate of the binder are the correct size nozzles for the type of binder, the angle of nozzle opening and the height of the spray bar. For a selected size nozzle, the angle of the nozzle openings and the height of the spray bar must be adjusted to spray the binder at a uniform thickness and at the required quantity across the full width of spraying application. 

The aggregate spreader applies uniformly and at a specified rate the aggregate (chippings) over the freshly spread surface with binder. The aggregate spreaders may simply attach to the tailgate of the truck (vane spreaders), mounted to the truck (hoppers on wheels) and propelled by reversing aggregate truck or self-propelled spreaders. 

The spreaders mounted to the truck usually contain augers to distribute aggregate and provide better control of the rate of spread compared to vane spreaders. The self-propelled spreaders have a receiving hopper and belt conveyors to carry the aggregate to the hopper spreader and offer high daily production rates. 

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