“Grinding” and “resurfacing” are sometimes used interchangeably by homeowners, but they are distinct processes with different purposes, equipment, and appropriate applications. Choosing the wrong one for your situation wastes money and may not solve the underlying problem.
The key distinction: grinding removes material from the concrete; resurfacing adds material to the concrete. Both can involve a final sealing step, but the directional change, taking away vs adding, determines which is appropriate for your specific problem.
What Is Concrete Grinding?
Concrete grinding uses rotating diamond-abrasive tooling mounted on a grinding machine to physically remove the top layer of the concrete surface. It is used for:
Surface preparation: Removing coatings, sealers, paint, or laitance (the weak top layer of concrete) to expose a clean, profiled surface for bonding of new coatings or overlays.
High-spot removal: Grinding down areas of concrete that are raised above the surrounding level, caused by joint faulting, tree root lifting, or pour inconsistency.
Surface texture modification: Grinding a rough or uneven surface to create a more consistent texture before sealing or polishing.
Crack and joint preparation: Grinding out cracks and joint edges before crack injection or joint sealant application.
Polishing: The final stages of polished concrete are also a form of grinding, progressively finer diamond tooling creates the polished finish.
When Grinding Is the Right Choice
Use grinding when:
- The concrete surface is fundamentally sound but has surface-level issues: coatings, laitance, minor roughness, or high spots
- You want a cleaner concrete surface without an overlay (grind and seal)
- Individual high spots are causing trip hazards between otherwise intact slab sections
- You’re preparing a surface for a new coating, most systems require at least light grinding to achieve adequate adhesion
- Polishing the existing concrete is the desired outcome
What Grinding Cannot Do
Grinding cannot add material, it only removes. Therefore it cannot:
- Fill in pits, potholes, or low areas in the concrete
- Repair cracks (grinding opens the crack, which then needs injection or filling)
- Correct areas where the concrete is below the surrounding level
- Significantly improve the structural performance of the slab
- Restore colour or finish uniformity to a concrete surface with inconsistent appearance
What Is Concrete Levelling?
Concrete levelling (also called concrete raising or slab lifting) refers to the process of returning sunken or settled slab sections to their original elevation. This is different from both grinding and resurfacing:
Polyurethane foam lifting (mudjacking): High-expansion polyurethane foam is injected under a sunken slab through small drill holes. The foam expands and lifts the slab back toward its original position.
Cementitious grout injection: A cement-based slurry is pumped under the slab to fill voids and raise the level.
Grinding for trip hazards: Where two adjacent slab sections have faulted (one is higher than the other), grinding the high edge down to meet the lower section removes the trip hazard without lifting either slab.
When Levelling Is Needed
Levelling is appropriate when:
- One or more slab sections have settled significantly (more than 10 mm)
- The slab surface was originally at the correct level but has moved due to subbase erosion or soft fill
- You need the surface to drain correctly and there is a drainage direction fault
- Steps between slab sections are causing trip hazards
What Is Concrete Resurfacing?
Concrete resurfacing applies a new layer of material over the existing concrete to:
- Correct surface imperfections (pitting, scaling, crazing, staining)
- Apply a new finish (decorative colour, texture, pattern)
- Add protection (sealer system, chemical-resistant coating)
- Improve drainage by building up low areas with a tapered overlay
The thickness of the resurfacing layer ranges from 1-2 mm (microcement, thin sealers) to 5-10 mm (polymer-modified overlays) to 15-25 mm (floor screeds used for significant levelling).
When Resurfacing Is the Right Choice
Use resurfacing when:
- The concrete has surface damage that grinding alone can’t address: deep pitting, spalling, extensive staining
- You want to change the appearance: colour, texture, pattern
- Multiple areas of surface damage need to be corrected in a single uniform application
- A high-specification protective coating is needed for chemical or wear resistance
- A self-levelling compound is needed to bring a low area up to the level of the surrounding concrete
The Relationship Between Grinding and Resurfacing
Here’s the key insight that resolves the confusion: grinding is usually the first step in resurfacing, not an alternative to it.
The standard concrete resurfacing process is:
- Grinding (surface preparation): Remove laitance, open pores, remove coatings, profile the surface
- Repair: Fill cracks and deep damage with repair mortar
- Prime: Apply primer coat to promote adhesion
- Overlay (resurfacing): Apply the polymer-modified overlay or coating
- Seal: Apply the topcoat sealant
When we say “grinding and sealing” without an overlay, we mean steps 1, (3), and 5, the middle resurfacing step is omitted because the existing concrete, once ground and cleaned, is suitable to seal directly without an overlay. This is the right approach when the concrete is structurally sound, the surface damage is minimal, and the goal is to improve protection and appearance without a full overlay.
Decision Framework
| Situation | Recommended Approach |
|---|---|
| Sound concrete, minor staining, needs protection | Grind and seal |
| Sound concrete, needs polished look | Grind and polish (multiple stages) |
| Surface pitting, scaling, spalling | Grind + polymer overlay (resurface) |
| Old paint or coating to remove | Grind to remove coating, then resurface or seal |
| One slab section higher than adjacent | Grind high edge (trip hazard removal) |
| Sunken slab section, drainage issue | Lift/raise slab, then resurface if needed |
| Completely deteriorated surface | Grind + full overlay or consider replacement |
| New decorative finish wanted | Grind + decorative overlay |
| Chemical-resistant coating needed | Grind + epoxy/polyurethane coating system |
Cost Comparison on the Central Coast
| Service | Cost per m² | Minimum Job |
|---|---|---|
| Diamond grind only (prep) | $12 to $22 | $300 |
| Grind and seal (no overlay) | $25 to $40 | $400 |
| Grind and polish (Level 2) | $55 to $90 | $600 |
| Grind and polymer overlay (resurface) | $55 to $90 | $700 |
| Polyurethane foam lift + grind + seal | $80 to $150 (lift) + grind cost | $1,200 |
| Full strip, grind, epoxy 3-coat | $45 to $80 | $800 |
A Common Scenario: Trip Hazard at a Control Joint
One of the most common concrete problems we deal with on the Central Coast is a concrete slab where two adjacent sections have faulted at a control joint, one side has settled or lifted slightly, creating a step of 5-20 mm. This is a trip hazard and in commercial properties, a liability issue.
The grinding solution: If the differential is 5-15 mm, grinding the high edge with a diamond cup grinder creates a gradual ramp over 50-100 mm that removes the trip hazard. This is quick, cheap ($80 to $150 for a typical joint), and effective. It doesn’t fix the underlying cause (the settled subbase) but it removes the immediate safety risk.
When resurfacing is added: If the rest of the driveway has also deteriorated, grinding the trip hazard and then resurfacing the whole area with a uniform overlay gives you a safer surface, better appearance, and protection, all in one visit.
When lifting is needed: If the differential is more than 20 mm, or if the joint is still moving (the gap is changing), grinding alone is a temporary fix. The slab needs to be lifted back to level and the subbase stabilised before grinding or resurfacing.
Frequently Asked Questions
Can grinding make a slippery smooth concrete surface slip-resistant? Yes. Diamond grinding creates a surface profile that increases the roughness of the concrete, grinding a smooth, polished-looking concrete step with a coarse diamond cup creates a noticeably textured surface. This is a simple, effective way to increase slip resistance on steps or paths without applying any additional product.
How deep does grinding go? Standard surface preparation grinding removes 0.5-2 mm of the concrete surface. Trip hazard grinding at a joint may remove up to 10-20 mm at the edge of the high section, tapering to zero over 50-100 mm. Polishing progressively removes 1-5 mm total across multiple stages. None of these depths affect the structural performance of a properly designed 100+ mm slab.
My concrete is uneven by about 20 mm across the driveway, can grinding level it? Not without dramatic thinning of the high areas. Grinding is not the right solution for correcting large-area levelness. Either polyurethane foam lifting (if a section has settled) or a self-levelling screed overlay (if the surface is generally uneven) is the appropriate approach. An independent contractor assesses which is needed on-site.
Will grinding change the colour of my concrete? Yes, typically. Ground concrete is a slightly different colour than unground concrete, it tends to be lighter and more uniform, revealing the paste and aggregate without the weathered surface layer. After grinding, the concrete’s appearance changes significantly, and this is actually the starting point for the new finish (whether sealed, polished, or overlaid).
How long does a grinding and sealing job take? For a standard residential driveway (50-60 m²), grinding and sealing typically takes 1 day for grinding and first seal coat, plus a second day for the final topcoat. The surface is usable the following day for foot traffic and within 48 hours for vehicles.
Not sure whether your concrete needs grinding, levelling, or resurfacing? Get a free on-site assessment, we diagnose the problem, recommend the right approach, and give you a clear price.