Construction process of radon-proof coating

　　The construction process of radon-proof coatings directly affects their radon-blocking effectiveness and durability and must strictly follow standardized procedures. The following are detailed construction process key points, explained step-by-step in combination with different application scenarios (new buildings, renovations of existing buildings):

　　I. Pre-construction Preparation

　　1. List of Materials and Tools
 

　　2. Substrate Condition Requirements

　　Dryness: Concrete/brick substrate moisture content ≤8% (detected by hygrometer), avoid moisture causing coating blistering and peeling.

　　Solidity: Remove loose layers, laitance, and oil stains. If the substrate is hollow, it needs to be removed and repaired.

　　Flatness: Surface flatness error ≤3mm/2m, cracks with a width >0.3mm need to be filled with repair mortar first.

　　II. Construction Process and Technical Key Points

　　(I) Construction Process for New Buildings (Taking Concrete Walls as an Example)

　　1. Substrate Treatment

　　Clean the surface: Use a broom and vacuum cleaner to remove dust and residual release agents. Wipe oil stains with alcohol or a special cleaning agent.

　　Repair Defects:

　　Honeycomb surface: Fill with 1:2.5 cement mortar or polymer putty, and grind smooth after drying.

　　Construction joints/cracks: Excavate a V-shaped groove (width-depth ratio 2:1) along the seam, fill it with sealant, and then cover it with fiberglass mesh (to enhance crack resistance).

　　2. Primer Application

　　Function: Seal substrate pores and enhance the adhesion of the radon-proof coating.

　　Operating points:

　　Apply the matching primer evenly using a roller or spraying method, with a dosage of about 0.15-0.2kg/m².

　　Drying time: Dry for 4-6 hours at room temperature (25℃), ensuring complete curing before applying the topcoat.

　　3. Radon-proof Coating Application

　　Number of coats: Usually 2-3 coats are required, with each coat applied in a perpendicular cross direction (e.g., the first coat horizontally, the second coat vertically) to ensure no omissions.

　　Coating amount: The amount per coat is about 0.2-0.3kg/m², and the final dry film thickness ≥100μm (detected by film thickness gauge).

　　Construction skills:

　　For easy-to-miss areas such as corners and pipe wall penetrations, first use a brush for "pre-coating", then roll-coat the large area.

　　When using air spraying, control the spray gun pressure at 0.3-0.5MPa, keep the nozzle 30-40cm away from the substrate, and move at a uniform speed.

　　4. Joint and Node Treatment

　　Corners: Paste 50mm wide fiberglass mesh, cover with radon-proof coating to enhance crack resistance.

　　Ground and wall joints: First fill the gaps with sealant, then brush the coating to form a continuous film layer.

　　Pipe interfaces: Make a 50mm radius arc chamfer around the pipe root, seal with sealant, and add a circular fiberglass mesh (diameter ≥200mm).

　　5. Maintenance and Acceptance

　　Maintenance time: Cure for 7 days at room temperature, avoiding water flushing, impact, or other construction pollution during this period.

　　Acceptance standard:

　　Appearance: The coating is free of bubbles, sagging, and cracking, with a uniform and dense surface.

　　Performance: After 7 days of construction, use a radon detector to compare the concentration, and the blocking efficiency is required to be ≥30% (refer to GB/T 16147).

　　(II) Renovation Construction Process for Existing Buildings

　　1. Original Coating Treatment

　　Old coating hollowing/peeling: Completely remove to the solid substrate, and use a bonding agent (such as cement-based bonding agent) to enhance the bonding force between the new and old layers.

　　Intact old coating: Grind the surface to roughness (roughness ≥60μm), remove dust, and then apply primer directly.

　　2. Key Reinforcement Areas

　　Basement floor: If the original floor is tiled, the tiles need to be removed and the adhesive cleaned, and the concrete substrate exposed before construction according to the new construction process.

　　Autoclaved aerated concrete wall: Due to its high porosity, the primer should choose a penetrating type (such as silane-modified primer) to increase the sealing effect.

　　3. Ventilation Cooperation

　　Keep the room well-ventilated during construction to accelerate paint drying; after construction, it is recommended to keep the mechanical ventilation system (such as a new air system) running for a long time to improve the overall radon prevention effect.

　　III. Construction Points for Special Scenarios

　　1. Humid Environments (such as basements)

　　Moisture-proof pretreatment: First, treat the base layer with cement-based penetrating crystalline waterproof coating (CCCW) to reduce moisture penetration, then apply radon-proof coating.

　　Coating waterproof enhancement: Add 10% waterproof agent (such as silicone waterproof agent) to the last coat of radon-proof coating to improve water resistance.

　　2. High-temperature Environments (such as kitchens)

　　Select weather-resistant coatings: Prioritize silicone丙 resin or fluorocarbon resin-based radon-proof coatings for better aging resistance.

　　Joint treatment: Use high-temperature resistant sealant (such as silicone weather-resistant sealant) at the joints between walls and ceilings.

　　IV. Construction Precautions

　　Environmental Conditions

　　Construction temperature: 5-35℃, relative humidity ≤85%, avoid working during rainy days or high-temperature exposure.

　　Winter construction: Antifreeze can be added (according to the paint manufacturer's recommended ratio), extending the drying time to 8-12 hours/coat.

　　Safety Protection

　　Wear masks and gloves to avoid skin contact with paint; when using solvent-based paints, ensure good ventilation to prevent VOC inhalation.

　　Waste paint and packaging materials should be sorted and disposed of; they should not be dumped indiscriminately.

　　Key to Maintaining Effectiveness

　　Regularly check the integrity of the coating, and repair any cracks or peeling promptly (repair steps are the same as new construction).

　　Retest the concentration with a radon detector every 2-3 years. If the barrier efficiency drops by more than 20%, recoating is required.

　　V. Common Construction Problems and Solutions