Asphalt paving: hot mix, prime and tack coats, sealcoat, striping and pavement checks

What the asphalt calculators cover

A paved surface is counted in layers and in the coats between them. The mix pages turn an area and a thickness into tons or tonnes of hot mix, count millings by volume and weight, and work out the material in a speed hump. The layer pages count the bituminous prime coat that penetrates and bonds a granular base and the tack coat sprayed between lifts. The care pages count sealcoat and crack filler, the marking pages count line paint, glass beads and the stalls a lot can hold, and the last group tests a pavement figure against a published method.

How the answers are worked out

Hot mix is volume times density. The driveway page uses a commonly cited average density for compacted hot mix and says that residential driveways are typically thin over a compacted gravel base, and the millings conversion notes that compacted millings are considerably denser than loose ones. The prime coat and tack coat pages both multiply an area by an application rate, which the reader enters. The sealcoat page gives the coverage of a squeegee-applied coat and says that spray application covers more area per gallon but is less common for DIY driveways, and the crack filler page counts tubes from a stated length of narrow crack per tube.

Markings are counted by rate and by count. The line striping page uses a coverage rate for a line of a standard width, the bead page takes bead mass as striped line area times the bead application rate and treats the beads as a separate material applied while the paint is wet, and it says the rate varies with the bead gradation under AASHTO M247 and the retroreflectivity the project asks for. The lot size page uses a stall and aisle size it calls a widely used planning guideline, and the single-row page rounds the stall count down, because a partial stall at the end of a row cannot be striped.

The checks follow named methods. The in-place density page turns the two specific gravities of a pavement core, from AASHTO T 166 and T 209, into percent of the theoretical maximum and the air voids. The ESAL page converts a traffic stream into design equivalent single axle loads on the AASHTO Guide's relation, in which damage scales approximately with the fourth power of axle load against the standard axle, and the structural number page sums layer thickness times layer coefficient, with drainage coefficients for the base and subbase, as the 1993 Guide does. The crown page finds the drop from centreline to edge as half the width times the cross-slope.

Units and documents by market

The market setting chooses the system the answers appear in: tons, gallons and feet for the United States, tonnes, litres and metres for the other three markets, each answer restated in the other system. The pavement checks on this hub cite AASHTO documents, and the stall and aisle sizes are given as a general site-planning guideline, so the metric answers are restatements of American methods. Read them against the specification your own authority sets. The glossary entry for asphalt, tarmac and blacktop gives the name each market uses for the surface.

Rates, rounding and whole units

Counts round up because tubes, gallons and loads are bought whole, and the single-row stall count rounds down for the reason above. The speed hump page applies a cross-section shape factor to length times width times height, since a rounded profile is not a full block, and the factor is an input. Every coverage and application rate on these pages is a starting figure the reader replaces with the product's own: the crack filler, the sealcoat, the line paint and the beads all say so.

The order the layers go down

The groups follow the build-up. The base is prepared and primed, the hot mix is laid and later lifts are bonded with a tack coat, and the surface is then sealed, repaired and marked. The checks group sits across all of them: density is read from a core, traffic and structural number set the design, and the crown sets the drainage cross-slope from the width of the pavement. A figure in one step feeds the next, and the tonnage of the mix follows from the thickness that the layers add up to.

What the calculators leave to others

The structural number page works from layer coefficients and thicknesses you supply, and the ESAL page from the traffic you supply, so neither designs a pavement. The in-place density page reports a percent of the theoretical maximum and the air voids from a core's two specific gravities. A thickness, a rate or a stall count is an input with a stated starting point, and the project specification governs.

Read an answer backwards

When you start from what you hold and want to know what it will cover, these pages run the same calculators in reverse.

• How long a driveway will my sealer cover?
• How many feet of parking lines will my striping paint cover?
• How many feet of driveway cracks will my tubes of crack filler fill?

Worked examples

A job worked through with its inputs and its working shown, so you can see the figures before you enter your own.

• An asphalt core, in percent of maximum density

  In-place density of an asphalt core taken from an under-rolled edge of a new mat

Reference tables

• Production rates by operation

  How long each operation takes one person, in person-hours per unit of work.

• Bulk densities of construction materials

  What a cubic metre of loose material actually weighs, in both systems, as this site's calculators compute it.

Guides

The practice behind the numbers: how the work is done, what goes wrong and how to check it.

• Overlaying an Asphalt Surface

  An overlay adds thickness to a surface that already has levels in it. What the old mat allows, what the ironwork costs, and how cores settle it.

• Industrial Asphalt Pavement & Sitework Prep

  A layer-by-layer read of an industrial asphalt section, from subgrade bearing up to joint density, with traffic loading setting every depth.

• Resealing and Restriping Asphalt

  A repaint is an alteration, not housekeeping. Why 244 stalls across two lots owe nine accessible spaces, and what that does to a seal-and-stripe.

• Laying Out a Car Park

  The vehicle you cannot turn away sets aisle width, stall angle and stall count on a site lot - lay it out from the swept path outward.

• Marking Out Lines and Sports Courts

  A court is a geometry problem that ends in a spray gun: how to set out, prove and record the lines before any paint is mixed.

• Traffic Calming and Signage on a Private Road

  Pricing an estate road's calming works: humps sized off their profile, a hole under every sign, and the glass that makes the lines exist at night.

Terms

• Asphalt / tarmac / blacktop
• Hardstanding and paved area
• Kerb / curb
• Fall and gradient

How the numbers are worked out

Every calculator names the method it uses and the standard or guidance behind it. These are the methods the most of the calculators above rest on, and the published documents they cite.

Methods

• Coverage Rate and Spread

  How a datasheet figure becomes an order quantity, why it is quoted per coat and calculated for a smooth plane, and what a real substrate does to it. Applies to 6 of the calculators above.

• Unit Conversion, Exactness and Rounding

  Why most conversion factors carry no uncertainty at all, which ones hide a material assumption, and why converting a measurement can never make it more precise than it was. Applies to 4 of the calculators above.

• Clearances, Layout and Accessibility Dimensions

  Why an accessible dimension is a measured anthropometric result rather than a round number, why a parking layout is set by the vehicle that turns worst, and why a door needs floor space on the side nobody draws. Applies to 2 of the calculators above.

• Fourth-Power Load Equivalency

  Why a pavement is designed around the few percent of traffic that is heavy, and cars are almost irrelevant to it. Applies to 2 of the calculators above.

• Volume from Geometry, and the Order That Follows

  Why the depth carries almost all the risk in a volume, why an excavation holds far more than its plan area suggests, and why a bag's yield is not its weight divided by a density. Applies to 2 of the calculators above.

• Head Loss, Falls and Surge: Resistance in Pipes, Ducts and Drains

  Why one pipe size up cuts the friction to a third, why a compressed flex duct can cost four times its rated loss, why a drain can be too steep, and why a fast-closing valve produces a pressure the pump never could. Applies to 1 of the calculators above.