Short answer
The attachments used in reinforced concrete demolition are well known; what makes the difference is the order they are used in. The correct order runs from mass reduction, to separating concrete from rebar, to cutting metal, to sizing. Each stage prepares the work of the next: unseparated material wraps around crusher bucket jaws, uncut rebar cannot enter the bucket, unseparated scrap loses its value. When the order breaks, what is lost is not only time but part of the recovery income.
Four stages, four different aims
- Mass reduction (breaker): brings the structural frame and large masses down to manageable pieces. The aim is speed, not surface quality.
- Separation (pulveriser): crushes concrete off the rebar. The aim is clean scrap and clean concrete; this stage decides the recovery income.
- Metal cutting (shear): cuts the exposed rebar and sections. The aim is clean metal at a transportable size.
- Sizing (crusher bucket): reduces the separated concrete to a reusable particle size. The aim is use on site.
Why the order decides so much
Each stage produces the input for the next. Skip the pulveriser stage and rebar stays inside the concrete; fed to a crusher bucket, that rebar wraps around the jaws and the work stops. Clearing it means stopping the machine and intervening by hand, and it repeats every time.
Skip the shear stage and long lengths of rebar become impossible to move and catch on equipment working around the site, which is both a safety and a productivity problem.
If the breaker stage is inadequate, masses that are too large arrive at the pulveriser; the pulveriser cannot grip them and its jaw is strained.
So the order is not a preference but the consequence of dependencies between stages.
The shortcut that time pressure creates
When the programme tightens, the stage most often skipped is pulveriser separation, because people say "we will sort it later". But mixed material cannot be sorted later; the cost of sorting far exceeds the cost of separating. That shortcut takes back the half-day it saved, and more, from scrap income and bucket stoppages.
Machine count and positioning
The ideal arrangement runs stages in parallel: one machine reducing mass while another separates. That requires at least two machines on site.
If working with one machine, a quick coupler becomes essential; otherwise the effort of changing attachments makes the operator blur the stages and the order breaks down.
Positioning follows material flow: the mass reduction area, the separation area and the product stock are laid out to follow one another. A layout where material has to travel back means extra handling at every stage.
Checkpoints between stages
- Breaker to pulveriser: are the pieces within a size the pulveriser jaw can grip?
- Pulveriser to shear: is the rebar sufficiently freed of concrete, or will the blade enter concrete?
- Shear to bucket: is the metal fully separated? A single long bar entering the bucket stops the work.
- Bucket to stock: is the particle size of the output suitable for the planned use?
- Asking this one question at each transition prevents most of the stoppages that would occur in the next stage.