Brick joint removal can be undertaken with hand-tools such as a chisel and hammer but this is only feasible for small areas or where extreme caution is required on sensitive structures. There are also wheeled hand-tools available but these are only suitable for very soft and loose mortars. For productivity and ease of achieving a consistent raked depth, a mechanised method of joint raking is usually chosen.
As a general guide, a brick joint should be raked to a depth equivalent to twice it’s height. So a typical 8 mm bed joint would need to be raked to a minimum depth of 16 mm. It is also important to achieve this depth consistently along the joint.
Of the two techniques used, the most common involves a diamond raking blade fitted to an angle grinder. The raking blade is usually much wider than a standard diamond cutting blade - 6.4 mm wide blades (1/4”) are most commonly used for brick raking. For high intensity brick raking, we recommend the use of 125 mm (5”) angle grinders as they are more powerful and have larger bearings and stronger gears. This means they should work faster for longer! 115 mm (4.5”) grinders are often preferred due to their smaller size and lower cost. We accept they may be suitable for less intensive work, such as raking perp joints, or for persons brick raking at a slower pace.
With either grinder size, the thicker brick raking blades are likely to cause gearbox bearings and motor brushes to wear more quickly. It is therefore important to check and replace these parts in good time if you are to get maximum life from the angle grinder. Most grinder manufacturers consider bearings and brushes to be wear components and therefore not covered by standard warranty.
Most mortar compositions contain substantial amounts of silica. Failing to control and collect dust when brick raking, places the operator and other persons in the vicinity at an increased health risk due to the inhalation of fine silica dust -prolonged exposure to silica dust inhalation is proven to cause permament lung damage.
Power tools such as angle grinders rely on a flow of air through the motor for cooling - where dust control and extraction is not being used, the dust laden air will coat motors, switches and other mechanical components, leading to overheating and early failure. And controlling dust at source also means there is no need for costly clean-up operations when the job is finished