Guides

How these quantities are worked out in practice, what the numbers mean, and what goes wrong on site. Written from road construction QA/QC experience rather than from textbooks.

• How to calculate asphalt tonnage on site

  Volume, density, wastage — and the three mistakes that turn a correct formula into a wrong order.

• Tack coat: application rates and what residual binder actually means

  If you do not know whether your specified rate is sprayed or residual, you can be out by a factor of two.

• Prime coat on granular base: rates, blinding sand, and when it is skipped

  A prime coat that sits on top of the base instead of soaking into it has done nothing.

• Field density testing: nuclear gauge, sand cone and cores

  Three methods, three different jobs. The disputes happen when someone treats them as interchangeable.

• Why asphalt cores fail density, and what to do about it

  Most failed cores are a temperature problem wearing a different costume.

• Reading a sieve analysis and spotting a failing gradation

  The curve tells you what the pavement will do long before the pavement does it.

• Bulking, swell and shrinkage: three factors people confuse

  The same soil has three different volumes. Order against the wrong one and the job stops.

• Rebar spacing: maximum spacing versus what gets tied on site

  The right number of bars in the bay does not mean every gap is legal.

• Ordering ready-mix concrete: quantity, wastage and what turns up

  The drawing quantity and the delivered quantity are never the same number. Plan for the difference.

• Trench excavation and backfill quantities

  Four separate volumes, three of which people forget to separate.