Short answer
What decides the attachment in road work is not how hard the material is but how much the quality of the edge matters. Asphalt is relatively soft and a breaker lifts it easily; but the edge it leaves is ragged, and where a patch is to be laid that ragged edge causes trouble later. So there are two different jobs on a road: wide area removal, where the edge does not matter, and patch excavation, where the edge decides the quality of the work. Speed wins in the first, the profile wins in the second. There is a third constraint, and it is often the most decisive: traffic.
Two different jobs
In wide area removal the aim is to lift the asphalt layer and where the edge ends is irrelevant. Here a breaker is fast and economic; the material removed is going to be taken away entirely anyway.
In patch excavation the aim is to lift a limited area and lay new asphalt in it. Whether the new asphalt bonds to the old depends on the cut edge being clean and vertical. A ragged edge lets water in at the joint, and the patch starts failing from its edge in the next winter.
Those two jobs do not use the same attachment. In patch excavation the edge is cut first and the inside lifted afterwards; a breaker cannot do the cutting.
Which job, which attachment
- Wide area asphalt removal: breaker with a blunt or wide tool. A moil point punches through asphalt without lifting it.
- Cutting the patch edge: concrete cutter or a saw. A vertical, clean edge decides the quality of the work.
- Lifting the inside of a patch: breaker or bucket; the edge is already cut, so no precision is needed here.
- Concrete roads and rigid pavement: breaker, followed by a pulveriser where there is reinforcement.
- Kerb and island removal: grapple or a small breaker; lifting a kerb without breaking it allows reuse.
- Surface profiling and level correction: drum cutter; it gives low vibration and a clean surface.
- Using the removed material on site: crusher bucket turns asphalt and concrete rubble into fill.
Working under traffic
Most road work is done with traffic still running, and that affects the attachment decision directly. Two constraints come in: flying fragments and time.
Flying fragments are a breaker’s weakest point: pieces of asphalt and concrete are thrown horizontally and can reach passing vehicles. So work close to traffic either needs a screen or a more controlled attachment. A drum cutter is markedly safer in this respect.
The time constraint relates to night working and lane closure windows. There speed wins and the decision turns towards the faster attachment; but where there is a fragment constraint, speed drops to second place.
Services under a road are closer than the asphalt suggests
The road body is where utilities are most densely packed: water, sewer, gas, electricity and telecoms usually run in the same section. Because the asphalt layer is thin, going deep with a breaker reaches a service faster than expected. Where the excavation will pass through the asphalt layer, a services search is mandatory.
Do and don’t
Do
- In patch excavation, cut the edge first and lift the inside afterwards.
- Use a blunt or wide tool for asphalt removal; a moil point punches rather than lifts.
- Working close to traffic, put up a screen or choose a more controlled attachment.
- Have a services search done where you will cut deeper than the asphalt layer.
- Count on using the removed asphalt and concrete on site; the haulage saving is significant.
Don't
- Do not try to form the patch edge with a breaker; the edge stays ragged and the patch fails from it.
- Do not remove kerbs by breaking them; an unbroken kerb can be reused.
- Do not push removed material aside with the breaker; that is lateral load.
- Do not accept a fragment risk under traffic on the grounds that "it will be quick".
- On concrete roads, do not try to bend and snap reinforcement with the breaker; cutting is a shear’s job and separating a pulveriser’s.
Removed material: waste or material?
On road jobs the asphalt and concrete taken up is treated as waste to be carted off site; yet both can become fill and sub-base material.
Rubble processed on site with a crusher bucket reduces both haulage cost and the cost of fill brought in. The gain grows as the haul distance grows.
How that calculation is built is covered in the on-site recycling guide; road work is among the most favourable settings for it, because the place the material comes from and the place it is needed are the same.