Updated and reviewed for practical accuracy on 20 July 2026.

Concrete floor preparation is the work that connects the existing slab to the proposed coating, polish or other finish. It is not one universal grinding pass. The required method depends on the slab, contamination, moisture, repairs, desired finish, product data, work-health-and-safety controls and the acceptance criteria for the project.

A useful preparation scope records what is known, what must be tested, what is included and what happens if hidden conditions are found. It should not promise a fixed lifespan, price, moisture threshold or return-to-service time before the slab and finish system are confirmed.

Define the finished floor before preparing the slab

Start with the intended use and finish. An epoxy or other resin system may require a particular surface profile, substrate strength, moisture condition, primer and environmental range. Mechanically polished concrete has different appearance, aggregate-exposure, repair and edge-detail outcomes. A levelling layer, adhesive or membrane has its own written requirements.

Record traffic, wheeled loads, chemicals, wet or dry use, cleaning, slip needs, drainage, temperature, UV exposure, shutdown limits and appearance expectations. Preparation should be designed backwards from those requirements and the selected system's current technical documents.

Survey the existing concrete

Inspect and map cracks, construction and movement joints, spalling, weak or dusty areas, laitance, high and low points, previous repairs, coatings, adhesive, oil, grease and other contamination. Note damp areas, water entry, drainage and changes between pours. Representative removal or trial areas may reveal conditions that are not visible from the surface.

Active movement, structural cracking, widespread delamination or unresolved water entry needs appropriate investigation before a finish is used to cover it. Grinding changes the surface; it does not diagnose the cause of a crack, restore structural capacity or stop groundwater.

Assess moisture for the selected system

A handheld meter can be a useful screening tool, but one generic reading cannot establish that every coating or flooring system is suitable. Test method, locations, slab age, ambient conditions, sub-slab barrier, water source and the manufacturer's acceptance limits all matter.

ARDEX Australia's flooring technical-bulletin library separates sources of damp-slab problems, moisture barriers, old adhesives, joints and other preparation topics. That illustrates why the proposed product and actual slab must be matched rather than relying on a universal percentage, drying time or neutralising treatment.

Where moisture is outside the selected system's documented limits, identify the source and obtain a compatible written response. Waiting, improving drainage, repairing water entry, using a specified moisture-management system or changing the finish may have different consequences and should not be improvised from a generic article.

Choose a preparation method from evidence

Preparation may include degreasing, removal of incompatible layers, diamond grinding, shot blasting, scarifying, local hand work, repairs and controlled cleaning. The method must expose sound concrete and create the profile required by the next product without unnecessarily damaging the slab or adjacent work.

ARDEX's current concrete surface-preparation bulletin path explains that the condition of the concrete and the subsequent material determine the preparation. Use the selected manufacturer's current instructions and a representative trial area where the substrate or finish is uncertain.

Acid washing, a general-purpose cleaner or a nominal machine pass is not an automatic substitute for mechanical preparation. Old coatings and adhesives may also contain hazardous substances or create disposal issues; identify them before disturbing the layer.

Plan cracks, joints and repairs separately

Classify each repair rather than treating every line in the slab the same way. A dormant cosmetic crack, active crack, construction joint, movement joint, surface spall and structural defect can require different materials and responsible parties. A rigid filler should not be assumed suitable across a joint intended to move.

Agree how repairs, aggregate variation and previous pours may remain visible in a polished finish. For coatings, confirm repair compatibility, cure, overcoating and movement details in writing. Keep a repair map for handover and future inspection.

Control silica dust and the work area

Grinding and polishing concrete can generate respirable crystalline silica. Workplace Health and Safety Queensland's floor-grinder guidance identifies water-delivery or suitable dust-collection systems as engineering-control options and links the applicable Queensland code and respiratory-protection requirements.

The site plan must address the current crystalline-silica-substance rules, equipment, isolation, extraction or water control, respiratory protection where required, housekeeping, slurry or dust disposal, air or health monitoring where applicable and protection of workers and other occupants. A visibly clean room does not prove respirable dust was controlled. Concrete grinding is not presented here as an unassessed DIY task.

Set acceptance checks before installation

Before applying the next layer or beginning the final polishing sequence, record the agreed checks for:

  • soundness, cleanliness and the required surface profile;
  • moisture method, locations, results and acceptance authority;
  • removed contaminants and any remaining limitation;
  • cracks, joints, repairs, edges, drains and transitions;
  • trial-area appearance or coating adhesion where specified;
  • ambient and substrate conditions required by the product data;
  • dust or slurry cleanup and protection of adjoining areas; and
  • who can approve work, variations and return to service.

Photographs, test results, repair records, product data and signed variations create a more useful handover than a broad statement that the floor was “fully prepared”.

Request a preparation-ready quote

Provide floor area, location, current use, proposed finish, slab history, photographs, known coatings or contamination, cracks, damp areas, access, operating hours and shutdown constraints. Ask the quote to state preparation assumptions, exclusions, safety controls, repair allowances, testing, trial areas, protection and the process for hidden conditions.

Review Wirth Floor's concrete grinding, polished concrete and epoxy flooring services, or send the slab and project details for a Brisbane or South East Queensland discussion.

This is general planning information, not a structural, hazardous-material, work-health-and-safety, product, standards or compliance determination. The responsible parties must set the project-specific tests, controls, repairs, preparation, finish and acceptance criteria.