Calculate the theoretical quantity of Prime Coat and Tack Coat required for highway construction works based on road length, width and approved application rate.
This calculator is useful for Site Engineers, Highway Engineers, QA/QC Engineers, Junior Engineers, Quantity Surveyors and Civil Engineering Freshers working on road and pavement construction projects.
Enter the pavement dimensions and approved application rate to calculate the theoretical material requirement.
The following examples explain how Prime Coat and Tack Coat quantities are calculated step by step. These examples are especially useful for freshers, junior engineers, site engineers and QA/QC engineers working on highway construction projects.
Consider a highway project where the WMM base course has been completed and Prime Coat is required before the subsequent bituminous layer.
| Road Length | 1,000 m |
| Road Width | 7.0 m |
| Surface | WMM |
| Approved Prime Coat Rate | 0.70 kg/m² |
First calculate the surface area over which Prime Coat will be applied.
For this example, assume that the approved project application rate is:
The application rate should not be selected merely as a default value. It should be established with reference to the applicable MoRTH requirement, project specification, approved material, surface condition, field requirements and Engineer's approval.
For a 1,000 m long and 7.0 m wide WMM surface, at an approved Prime Coat application rate of 0.70 kg/m², the theoretical Prime Coat requirement is:
4,900 kg = 4.90 tonnesA fresher should understand that the calculated quantity is the theoretical quantity based on the approved application rate.
In this example, every square metre of the 7,000 m² surface is assumed to receive 0.70 kg of Prime Coat.
Do not assume that the calculated theoretical quantity is automatically the actual quantity sprayed in the field. Actual application must be controlled through proper distributor calibration, spray-bar settings, travelling speed, nozzle condition, spray pattern, material measurement and field verification.
Suppose an existing bituminous surface is being prepared to receive a new bituminous overlay. Tack Coat is required to provide adequate bonding between the existing and new layers.
| Road Length | 1,000 m |
| Road Width | 7.0 m |
| Receiving Surface | Existing Bituminous Surface |
| Approved Tack Coat Rate | 0.20 kg/m² |
The theoretical Tack Coat requirement for the 7,000 m² bituminous surface is:
1,400 kg = 1.40 tonnesConsider a granular pavement surface that has already been treated with primer and is to receive the next bituminous layer. Assume the approved Tack Coat application rate is 0.25 kg/m².
| Length | 1,000 m |
| Width | 7.0 m |
| Area | 7,000 m² |
| Approved Tack Coat Rate | 0.25 kg/m² |
The theoretical Tack Coat requirement is:
1,750 kg = 1.750 tonnesNow consider a cement concrete pavement receiving a bituminous overlay.
| Length | 500 m |
| Width | 7.0 m |
| Approved Tack Coat Rate | 0.30 kg/m² |
The theoretical Tack Coat requirement is:
1,050 kg = 1.050 tonnesThe following values are useful for understanding the calculation. The actual rate used on a project shall be confirmed from the applicable MoRTH provision, project specification, approved material, surface condition and Engineer's approval.
| Application | Surface | Indicative Rate | Example |
|---|---|---|---|
| Prime Coat | WMM / WBM granular surface | 0.70–1.00 kg/m² | 0.70 kg/m² |
| Tack Coat | Existing bituminous surface | 0.20–0.30 kg/m² | 0.20 kg/m² |
| Tack Coat | Granular surface treated with primer | 0.25–0.30 kg/m² | 0.25 kg/m² |
| Tack Coat | Cement concrete pavement | 0.30–0.35 kg/m² | 0.30 kg/m² |
Application rates shown above are provided for engineering understanding and calculation examples. They should not be treated as a universal fixed rate for every highway project.
The actual application rate shall be based on the applicable MoRTH Specifications for Road and Bridge Works, Section 500, relevant table, project-specific specifications, approved material, surface condition, field requirements and Engineer's approval.
Always verify the latest contract specification and applicable MoRTH revision before using the rate for contractual measurement or payment.
Never select a Prime Coat or Tack Coat rate simply because it was used on another project. The required rate depends on the surface, material, project specification and applicable MoRTH requirements.
Use the calculator to determine the theoretical quantity after entering the approved application rate. The calculator does not replace the project specification, approved method statement, field trial or Engineer's instructions.
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