Bush hammers come with cylindrical tungsten carbide tips in various sizes, with larger diameter tips offering a more significant protrusion to remove more material in a single pass, resulting in a deeper cut and more pronounced texture. Smaller diameter tips protruding less will provide finer texturing, requiring multiple passes for deeper cutting.
The spacing between the tips also affects results. Wider spacing can yield large individual impacts and more distinct texturing. Narrower spacing creates overlapping impacts for a more uniform surface.
Consider factors like concrete characteristics, required aggregate exposure, slip resistance goals, applicable codes and standards, and aesthetics when selecting bush hammering as the right technique for the job. Discuss samples with suppliers like us to choose the proper bush hammer for consistent, repeatable results across every job.
Concrete Surface Profiles
When bush hammering concrete for overlays or coatings, achieving the specified Concrete Surface Profile (CSP) is essential. The International Concrete Repair Institute (ICRI) defines CSPs on a scale of 1-10, indicating average surface amplitude.
CSP 1 is nearly flat with no significant texture, while CSP 10 has an average amplitude over 1⁄4 inch. The appropriate CSP depends on coating type, environmental exposure, and service conditions.
You achieve these CSPs with the appropriate reel - more aggressive tools yield rougher textures in the CSP 5-10 range, while tools with smaller diameter tips create smoother CSP 1-3 profiles.
The Bush Hammering Process
Bush hammering uses repeated mechanical impact to fracture and remove concrete surface material. It uses a rotating reel with protruding tungsten carbide tips mounted on floor grinding machines.
The process begins after initial surface preparation through grinding or other methods. The floor grinding machine must operate at the bush hammer's proper weight setting, angle, and travel speed, as excessive forces can damage the surface.
The floor grinding machine is systematically passed across the concrete surface in overlapping paths, allowing the hammer tips to remove high points and fracture material. A uniform texture is achieved by maintaining consistent travel speed, weight/down pressure, and overlap between adjacent passes.
Additional passes are made with the bush hammer reel for further depth of cut. The process continues until you achieve the ideal surface finish and depth - the surface is cleaned thoroughly afterwards with a brush.
A well-executed bush hammering process fractures the surface matrix and exposes aggregate uniformly without damaging the underlying concrete. The fractured surface provides an ideal profile for the mechanical bonding of overlays and coatings, creating superior adhesion compared to an untreated surface.
Removing flaws also prepares the substrate for treatments. Eliminating defects like deposits, fins, drips, and protrusions ensures a consistent canvas for coatings. Bush hammering does not cut as deeply as methods like scabbling, which can undermine integrity.
Browse our complete range of bush hammers here and contact us for help specifying the best ones for your application.
Further reading
- https://www.pwm-sales.co.uk/applications-for-bush-hammers/
- https://www.pwm-sales.co.uk/how-does-a-bush-hammer-work/
- https://www.pwm-sales.co.uk/what-is-a-bush-hammer/
- https://www.pwm-sales.co.uk/when-is-bush-hammering-the-correct-technique/
- https://www.pwm-sales.co.uk/products/floor-preparation/
- https://en.wikipedia.org/wiki/Bush_hammer
- A study of the characteristics of cementitious surface toppings and applied concrete (hse.gov.uk)