Spalled concrete is flaking, cracked, or delaminated surface material, sometimes exposing aggregate or reinforcing steel beneath, and it must be removed and properly patched before any coating goes down. Coating does not repair a spall. Repair and coating-readiness requirements come from the repair mortar and coating data sheets. This guide is written for facility managers, property managers, general contractors, and building owners who are scoping a coating project and need to understand what spall repair involves before they sign off on a quote. It does not cover joint or crack stabilization, expansion joints, or saw-cut treatment — those are addressed in separate guides.
A spall is a section of concrete where the surface layer has cracked, flaked off, or separated from the slab below, sometimes down to the level of reinforcing steel. Spalls can appear as shallow surface pitting or as deeper areas where chunks of concrete have broken away entirely.
Unsound concrete is generally removed and the area repaired with a product suited to the depth before coating; the coating and repair data sheets set the requirements.
Before any repair material is selected, the spalled area needs to be mapped and categorized so the contractor knows how deep to go and what repair profile to use.
Where corroded reinforcing steel is the cause of cracking, spalling, or delamination, ICRI 310.1R outlines the steps for preparing concrete for replacement material in those areas, including exposing and undercutting the reinforcing steel, edge and surface conditioning, and removal geometry.
Once the surface is cleaned and opened up, the method used to prepare it for the coating itself follows a different selection process, covered in the guide to concrete surface prep methods. Contractors offering this kind of diagnostic and prep work can be found through the Colorado Concrete Surface Preparation contractor hub.
Repair mortars are not interchangeable. Each product has its own minimum and maximum layer thickness, its own stance on feather edging, and its own stated timing before it can be coated. Using a product outside its data-sheet layer range, or feather-edging a product that prohibits it, departs from the manufacturer's instructions. Vertical patching mortars are not floor-grade repair products, and data-sheet timing must be confirmed before any product is specified for a floor repair.
| Product (per manufacturer data sheet) | Layer range | Feather edge? | Coating readiness |
|---|---|---|---|
| SikaQuick-800 (horizontal rapid repair mortar) | 1/2 in. minimum neat, up to 8 in. per lift | Do not feather edge | Epoxy as early as 6 hours at 73 °F |
| SikaQuick Pro 1000 (horizontal repair mortar) | 1/4 in. to 2 in. neat | Should not be feather edged | Foot traffic in 4 hours; epoxy as early as 6 hours |
A repair mortar has to bond to the surrounding sound concrete and reach an appropriate state before the coating is applied over it. These are two separate questions, and both should be addressed in the scope.
ASTM C881/C881M covers two-component epoxy-resin bonding systems for application to portland-cement concrete, classified by type, grade, class, and color. If a bonding agent is specified, ask the contractor to name the type, grade, and class if it references ASTM C881/C881M.
Each repair mortar has its own stated minimum time before it can be coated, and that timing is tied to the specific product and the test conditions on its data sheet — for example, SikaQuick-800 lists epoxy coating as early as 6 hours at 73 °F per its data sheet. Site conditions on the day of installation, including slab temperature, should be checked against the data sheet rather than assumed.
A written scope for spall repair before coating should itemize each of the following so there is no ambiguity about what was done and when:
For budgeting, use the FloorSpec cost calculator to estimate installed cost by service and Colorado city, and compare that against quotes that clearly itemize the repair and coating scope separately. Facilities such as warehouses and distribution centers can find coating-specific contractors through the Colorado Commercial Epoxy Flooring contractor hub or the warehouse and distribution center facilities hub.
Ask the contractor to confirm in writing how unsound concrete will be removed and repaired before coating; do not coat over it. The spalled concrete needs to be removed and patched with an appropriate repair mortar before the coating is applied.
That depends on how deep the deterioration goes, which is why assessment (sounding the slab, marking the damage, checking for exposed reinforcing steel) happens before a repair mortar is chosen. Different repair mortars are rated for different layer thickness ranges, so the depth of removal determines which product fits.
The two repair mortars shown here instruct not to feather edge. Confirm the feather-edge policy on the specific product's current data sheet before the repair is placed.
Coating-readiness timing is listed on the mortar data sheet; confirm the exact figure and any stated conditions against the current data sheet. Confirm the exact figure and any stated conditions directly against the current data sheet rather than assuming a standard wait time applies across products.
No. Crack and joint stabilization is a separate scope item and is covered in a dedicated guide; make sure your written scope states clearly whether that work is included.
Ask for the specific repair mortar product and its layer thickness range, whether a bonding agent is used, the coating-readiness time and its source on the data sheet, and the target surface profile for the patched area. You should also confirm in writing whether joint, crack, or saw-cut work is included or billed separately.
How cracks and joints are repaired and stabilized before a coating goes down, which fillers fit which joints, and what the scope should say.
How diamond grinding, shot blasting, scarifying, and acid etching compare for commercial concrete prep, with the surface profiles each produces.
How moving joints are carried through a commercial coating system: why rigid coatings should not bridge them, flexible sealants, and joint covers.
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