Preparation of concrete — practical guidance and quality checks
The concrete must be set, clean, free of cement laitance, oils and weak layers, and its moisture content must correspond to the system. The most important thing is to prepare the input conditions, the correct order and control the result before moving on.
In brief
The concrete must be set, clean, without cement laitance, oils and weak layers, and its humidity must correspond to the system.
The most important are the prepared input conditions, the correct sequence and the control of the result before proceeding next.
Goal and result of the stage
The "Concrete preparation" process is used to obtain a load-bearing surface that is clean, dry, even and compliant with the requirements of the next layer.
When to perform this step
This topic should be considered after dismantling and installation repairs, immediately before priming or applying the finishing layer.
The term results from technical dependencies. Doing it too early may result in damage to the finished work, and doing it too late may result in blocking access or requiring corrections.
What must be ready before start
Before starting, prepare: assessment of adhesion, moisture, absorbency, evenness and type of existing layers.
Materials, tools and documents
Typical materials and auxiliary elements: repair compounds, leveling mortars, cleaning and degreasing agents, crack strengthening materials.
Typical tools and equipment: spatula and scraper, sander with suction, level or patch, moisture meter matched to the substrate, vacuum cleaner industrial.
Correct execution order
- Diagnose the load-bearing capacity, evenness, absorbency, humidity and type of existing layers.
- Remove only weak layers, dirt and elements limiting adhesion.
- Repair defects, cracks and unevenness with a material compatible with the substrate.
- Leave the layers until set or dry in accordance with the product documentation.
- Dust, clean and re-inspect the substrate before priming or finishing.
Execution conditions
Control temperature, humidity, ventilation, substrate condition and conditions specified by the manufacturer. Drying or setting times depend on product, layer thickness and conditions - do not shorten them based on surface appearance alone.
If different system instructions specify different requirements, adopt a more stringent condition or confirm with the manufacturer.
Quality Control
Perform acceptance in conditions appropriate for subsequent use and before covering the work with another layer.
- the surface has equal load-bearing capacity
- release agents and contaminations have been removed
- cracks and expansion joints are recognized
- the substrate is load-bearing, clean and free from layers limiting adhesion
Safety and boundaries of independent work
Dust from old layers can be harmful. Limit its spread, use suction and respiratory protection. Do not sand material of unknown composition until it has been identified.
Common errors
- priming on cement laitance
- rigid closure of working cracks
- finishing of immature or damp concrete
- applying new layers on dust, grease, weak paint or damp substrate
Difficulty, time and risk of errors
Execution variants
The substrate can be repaired locally, completely leveled or a new system solution can be created. The least invasive method only makes sense if the layers left behind are truly load-bearing.
What to do next after finishing
After preparing the substrate, apply the appropriate priming or layer provided by the system. Do not allow other works to re-dirty and damage the received surface.
Frequently asked questions
What does “Concrete Preparation” involve?
The concrete must be set, clean, free of cement laitance, oils and weak layers, and its moisture content must correspond to the system. The most important thing is to prepare the input conditions, the correct order and control the result before moving on.
What needs to be prepared before the "Concrete Preparation" stage?
Before starting, prepare: assessment of adhesion, moisture, absorbency, evenness and type of existing layers.
How can you verify that “Concrete Preparation” has been done properly?
Apply in conditions suitable for subsequent use and before covering the work with another layer. • the surface has equal load-bearing capacity • release agents and contaminants have been removed • cracks and expansion joints are identified • the substrate is load-bearing, clean and free from layers limiting adhesion
When is it better to entrust the "Concrete preparation" stage to a specialist?
Outsource work when it involves active installations, structures, tightness, large or heavy components, or requires equipment and experience that you do not have. Don't study on a high value ready-made surface.