Automation & Robotics for Construction
Automated Concrete Grinding for Wall and Ceiling Surfaces
Background and Current Practice
Concrete grinding is done to remove the defects on the concrete surface, such as unevenness, bulges and drips, so the quality of the architectural finishes is not affected. Currently, concrete grinding is performed manually by workers using handheld grinders. This operation is not only labour intensive but also poses health and safety hazards to the workers, especially during long periods of grinding work. In order to grind concrete surfaces that are beyond the reach of the worker, for example, walls with heights between 1.5m and 6m, and ceilings, work-at-height equipment is needed. Working at height adds complexity, requires more manpower, and also presents additional safety risks that need to be managed.
Often, the surface finish of grinded concrete surfaces still requires additional treatment, such as skim coating and plastering, before it is ready for a paint finish. As a guide, Concrete Surface Profiles (CSP) were developed by the International Concrete Repair Institute (ICRI) to divide concrete surface treatments into 10 classifications. They are named from CSP 1 to 10 – with CSP 1 being the finest and smoothest surface, and CSP 10 being the roughest and most uneven surface.
For concrete grinding, CSP 1 or CSP 2 is the expected level. Also, the concrete surface should be ready to receive finishes, for example, paint finish, of not more than 10mm.
Opportunity Areas and Key Challenges
We are interested in robotic solutions that are able to partially automate concrete grinding works as a start and can later be developed into a fully-automated solution. In the early development stages of the solution, the workers can deploy it to do the grinding for a chosen section of the wall or ceiling, and after the work for that section is complete, return to turn on the machine for the next section. This then frees up the workers to perform other activities while eliminating the safety risk associated with grinding.
The current intent is to use the solution to grind the surfaces of a cast in-situ or precast wall that are casted from a typical concrete formwork. The surface profiles of such concrete surfaces are usually even, except for some minor bumps and drips.
The solution should fulfil the following requirements in order for it to considered successful:
- It must accurately grind all of the assigned surfaces to produce a consistent surface quality.
- It must accurately identify the quality and defects of the concrete surface and adapt the grinding accordingly.
- It must be able to perform concrete grinding work on a surface area of no less than 8m2 an hour.
- It must grind surfaces of up to 3m in working height
- It must allow for Interchangeable parts, such as different types of grinding discs and grinding activities.
- The resulting quality of work from the solution must comply with International Concrete Repair Institute’s guide on CSP, where the quality standards for internal and external finishes works shall adhere to CSP 1 to 2, and also to comply with BCA CONQUAS 2019 (Appendix 1, Architectural Finishes, Item 2a - Internal Walls & Appendix 2, External Wall, Item 1 – General Requirements ) as further supplementation.
- The grinding must be performed in full consideration for safety on site and environmental impacts.
- The solution must support the capture of data related to the work done, such as location, duration and errors, for progress tracking and inspection purposes.
- It must be able to operate on site during the construction phase where there are only construction power sources i.e., on-site power generators.
- The solution must be able to fit into material hoists or other equivalent vertical transportation, or work-at-height equipment, with consideration for its size, weight, and portability.
It is also desirable for the solution to meet the following performance specifications:
- It is designed to access heights of up to 6m or to integrate with the common work-at-height equipment for elevation.
- It should ideally improve the quality of works to reduce or eliminate surface treatment works required in order to prepare for the paint finish.
- It should be able to traverse and park on uneven, sloped or stepped areas.
- It should consider how grinding can be done for the following joint areas : 1) joint areas between vertical or horizontal elements (e.g.: slab soffits, wall and floor joints and 2) joint areas between vertical-vertical elements or horizontal-horizontal elements (e.g.: areas between walls and slabs)
The ideal solution can autonomously perform concrete grinding, change grinding parts, and navigate a building floor. For a start, the solution should complete the concrete grinding work on a surface area without human intervention except for deployment, redeployment and termination, and do so accurately and quickly (over 8m2 an hour).
This reduces or eliminates the need for manpower, allows for remote execution and reduces the total cost and time needed to prepare a concrete surface for receiving architectural finish.