Reusable brackets versus timber waste: what a year of pours leaves behind
Every slab edge formed with timber bracing leaves a pile behind: cut-offs, bent pickets, nails and a skip bill. Every slab edge formed with a reusable bracket leaves a stack of brackets going back on the rack. This is what the difference adds up to across a year of pours, and why the sustainability case and the cost case are the same case.
What gets thrown away on a timber-braced edge
Take the 100 metres of 300 mm slab edge from the cost-per-pour worked example. Braced the traditional way it uses about 200 star pickets and around 100 metres of timber bracing behind the form. The bracing is cut to the job and nailed; it splits, fills with nail holes, and 10 to 20 percent of it goes missing along the way. Ask a crew what they actually buy and the answer is simpler than any reuse rate: the lot again, about every three months. Over a year that is four fresh orders, around 400 linear metres of bracing timber bought, cut and thrown away for one crew, before the edgeboard itself.
The pickets could last a hundred pulls on paper. On site they bend, the tops mushroom, they get buried under fill or leave with another crew, and they go on the same quarterly order: around 800 pickets a year.
Left: timber bracing, cut and nailed to the job and binned when it is worn out. Right: FlexEdge 600 at Kogan Creek, going back on the truck after the strip.
What comes back with a bracket
An EdgePro bracket is set against the board, anchored through its base with two FixEdge anchors and screwed to the board through its face. At the strip the screws back out, the anchors lift, and the bracket goes in the stillage. The polymer brackets are rated for 500 or more pours with normal site care, the ground screw anchors for about the same, and the StarPeg anchors until they bend or the top mushrooms, which the built-in cap slows. The edgeboard itself is the only consumable that stays the same on both methods, and with the FRP composite board it stops being a consumable too.
Nothing is cut, so there are no offcuts. Nothing is nailed, so there is no nail litter in the fill. Concrete knocks off the polymer without oil, so the bracket goes back in the stillage clean.
The stillage is where the system lives between pours: 50 or 80 FlexEdge, forklift access, stackable three high.
The numbers, per year, one crew
Assumptions as in the cost-per-pour article: a crew pouring 100 metres of edge twice a week, 48 weeks a year, about 96 pours.
| Pickets and timber | EdgePro FlexEdge 600 | |
|---|---|---|
| Bracing timber thrown away | About 400 linear metres a year, a fresh set each quarter | None |
| Steel pickets replaced | Around 800 a year, the lot each quarter | None; anchors reused |
| Nails into the fill | About $1,500 of nails a year, left in offcuts and fill | None; screws back out |
| Skip and disposal | A set of bracing every quarter, plus offcuts every job | Concrete knocked off, brackets racked |
| Bracing hardware bought | The lot again about every three months | Once, then 500 pours |
The same table in dollars, on the same footing as the cost-per-pour article: the lot bought again about every three months. Prices as in that article: pickets at $8, bracing timber at $10 a metre, nails and the other consumables at $50 a pour, labour at $70 an hour with set-out, pour and strip taking half the time on brackets, and the bracket set at $116 a bracket plus two $18 anchors, bought once.
| Every three months, one crew | Pickets and timber | EdgePro FlexEdge 600 | Difference |
|---|---|---|---|
| Star pickets, 200 at $8 | $1,600 | $0, anchors reused | $1,600 |
| Bracing timber, 100 m at $10/m | $1,000 | $0, nothing cut | $1,000 |
| Nails and other consumables, 24 pours at $50 | $1,200 | $0, screws back out | $1,200 |
| Gear and consumables, every quarter | $3,800 | $0 | $3,800 |
| Extra labour, 11 hours a pour at $70, 24 pours | $18,480 | $0 | $18,480 |
| Every quarter, all in | $22,280 | $0 | $22,280 |
| Every year | $89,120 | $0 | $89,120 |
| Bracket set, bought once | $0 | $12,768 | $12,768 in year one only |
Gear alone, the bracket set is $2,432 ahead by the end of year one: $15,200 on pickets, timber and nails against $12,768 once. Count the labour and it is $76,352 ahead in year one and $89,120 ahead every year after, with the same stack still in the stillage. Over five years that is $445,600 against $12,768. The waste and the spend are the same thing.
Kogan Creek Power Station with Next Civil: the brackets in this run go back on the truck after the strip.
Where it matters on a tender
Head contractors on civil and government work increasingly ask for waste minimisation and material reuse in the tender response. A reusable bracing system is a concrete answer: fewer skip movements, less timber, no nails left in the fill, and the kit goes from one project to the next. EdgePro brackets have been used on the North East Link, Gold Coast Light Rail and Byford Rail, by a different contractor on each job, and on each one the bracing came off at the strip and went back on the rack instead of into the skip.
The practical side
- Brackets can go into the stillage wet and dirty. The mesh drains. Hose the cage down with the brackets in it.
- Knock concrete off before it cures hard. The polymer releases cleanly without oil.
- Keep polymer out of long-term direct sun where practical, as with any polymer site product.
- Retire a bracket with a crack through a bearing face or web, or a pin hole that has elongated. Everything else keeps going.
Run the cost-per-pour sum on your own numbers and the waste follows. The worked example is here. The full range is priced per bracket, and the datasheet pack has the reuse ratings for every product.