Quality Control during Road Construction - Part 3, Bituminous Construction - from Prime coat to SMA 

Yes, it is ready. will upload soon. Last minute finishing touches are required.

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Grade depends on climate. DBM is laid with VG40 and BC with VG40 or PMB40 depending upon the climate of the area. IRC 37 gives some guidelines for selection of the binder.

hardrer grade in the upper layer, because it is the layer which takes the load directly. It is the layer exposed to heat, dust and air.

Prime Coat: The application rate typically varies depending on the type of surface being treated. For WMM (Wet Mix Macadam) surfaces, the application rate might be between 0.6 to 1.2 kg/sqm, and for granular surfaces, it can be from 0.9 to 1.5 kg/sqm. The specific type of binder used (like MC-30 or MC-70) and its viscosity will influence the pressure settings on the distributor bar. Tack Coat: The application rate usually depends on the type of surface over which the next layer is to be laid. For a bituminous surface, the rate might be 0.2 to 0.3 kg/sqm, and for a granular or treated surface, it might be 0.3 to 0.5 kg/sqm. The specific pressure to be maintained in the distributor bar would depend on the viscosity of the material being sprayed, the width of the spray bar, and the desired rate of application. The equipment manual or guidance from the manufacturer would provide precise pressure settings.

@@Raj-ni8xs thank you sir

Sorry, I do not have much idea of pressure in distributor bar. But before start of the work, demonstration trial is done and the rate of application is measured. It will naturally depned on size of the nozzle and pressure in the bar.

@@SatishIITR ok thnk u sir

could not understand.