From the plant to the finished mat — lifts, density, tonnage, compaction, tack coat, joints, cores and QC in plain language, with the free tools to go with each step.
Asphalt is placed in layers (each layer is a lift), on top of a compacted granular base.
On a two-lift job you'll hear binder and surface:
Below the asphalt sits the granular base. In Ontario it's usually Granular A directly under the asphalt — a well-graded crushed granular that compacts into a firm, drainable base — over Granular B, a coarser material used for the deeper sub-base and bulk fill. The subgrade (native soil) is the bottom. All of it has to be shaped and compacted before the first lift goes down: asphalt is only as good as what it sits on. Layer requirements come from the project spec (in Ontario, typically OPSS) — the numbers here are typical, not universal.
Tonnage is volume × density. In Canada we work in metric.
Hot mix asphalt is typically around 2,350 kg/m³ (about 2.35 tonnes per cubic metre). The exact number comes from the mix design — but 2.35 t/m³ is the standard starting point used on site and in SummitTools' calculators.
Yield is the actual tonnage placed versus the theoretical amount for the area — watch it job to job. If you consistently place more than the calculation says, check the mix density on the plant ticket, the effective mat width, and the actual compacted thickness.
Example: a 120 m × 3.7 m lane, 50 mm thick at 2.35 t/m³ with 2% waste:
Lift thickness is checked with cores — and how it's judged depends on the spec.
After the mat is compacted, cores are taken and measured. A two-lift core shows the total thickness, the surface lift, and by subtraction the binder lift. On many jobs each lift has its own minimum (e.g. binder 70 mm, surface 50 mm). How acceptance works varies by job: some specs judge by the average across all samples, others require every individual sample to meet the number. Check your spec — and record both the individual results and the running average either way.
Compaction is how the mat gets to its required density — usually checked as a percentage.
Asphalt density is compared with the reference density named in the project specification — often the mix's maximum relative density (Gmm) or another contract-defined reference. It is checked with a properly correlated nuclear density gauge or with cores. The required percentage, test method, lot rules, and any edge or joint adjustments all come from the job specification. Rolling normally moves through breakdown, intermediate, and finish stages while the mat remains inside the workable temperature window.
The three stages are roles, not a promise that three passes will achieve density. Roller type, speed, vibration, overlap, number of passes, mat thickness, temperature, and mix all affect the result. Establish and follow the approved rolling pattern; rolling too late may stop gaining density or damage the mat.
Tack is the thin adhesive layer that bonds one lift to the one below it.
Tack coat is sprayed on the prepared surface before each new lift so the layers bond instead of slipping. It's usually an emulsion applied at a light rate (often in the range of 0.2–0.5 L/m² depending on the surface and the spec). Rates matter — too heavy and the mix can bleed, too light and the layers can delaminate.
Tack also needs to break (cure) before the next lift goes down — paving onto unbroken tack can let it pick up onto truck and paver tires. When in doubt, give it time and check the spec's guidance for the emulsion being used.
Where mats meet and where mix separates — the two things inspectors look at hardest.
Longitudinal joints run along the direction of paving where two passes meet; transverse joints run across where one day's paving ends and the next starts. Both are weak spots if not compacted properly — cold, open joints are the first place water gets in and failures start.
Joints are called hot when the adjoining mat is still workable (paved hot-into-hot), and cold when the edge has set. Cold joints need extra care — tight, well-compacted, and usually painted or heated before the new mat touches them.
Segregation is when the mix separates: coarse rock ends up in one spot and fines in another, leaving a rough, open-looking patch. It usually comes from mix handling — too much shoveling, dumping, or trucks not remixing. A segregated mat doesn't compact evenly and fails early.
Cores are the proof — they show thickness and let the lab check density.
Core samples are cut out of the compacted pavement, usually by lot, and measured. On a two-lift job each core can show the total, the surface lift, and the binder lift. Core results feed the QC record and the acceptance decision — which is why SummitTools' Field QC page logs them by station and averages them the way the spec does.
The order that makes a day work.
Weather governs the schedule too: most specs set limits on mix temperature at delivery and won't allow paving in rain or on a wet surface. A cold mix or a shower mid-pour can force a joint you didn't plan for.
The kind of stuff you learn standing on the mat.
Use the calculators for planning, log your cores and compaction in Field QC, and build the daily report from the same numbers.