Redispersible polymer powder is often used in concrete repair. The core is to incorporate it into the repair mortar to enhance the adhesion, flexibility and durability between the mortar and the old concrete base. The specific construction method is as follows:
1. Base treatment
Clean the loose dust, oil stains and loose layers on the surface of the concrete to be repaired, rinse it thoroughly with a high-pressure water gun and let it dry. For cracked or defective areas, the damaged parts should be removed to a solid base layer. If necessary, mechanical roughening should be used to increase the surface roughness.
2. Preparation of repair mortar
Dry-mix cement, quartz sand, redispersible latex powder (the dosage is generally 3% to 8% of the mass of the cementitious material), cellulose ether and other admixtures in the prescribed ratio evenly, and then add an appropriate amount of water and stir to form a mortar of moderate consistency. Latex powder should be mixed with dry powder first to avoid direct addition of water causing lumps.
3. Construction operations
First, apply a layer of latex powder modified interface agent (a mixture of latex powder, cement and water) on the treated base to enhance the adhesion between the new and old interfaces. After the interface agent is slightly dry, apply the repair mortar in layers. The thickness of each layer should not exceed 20mm. Use a trowel to press and smooth it out. For deeper defects, layer curing is required before layering and construction.
4. Maintenance treatment
After the construction is completed, cover the surface of the mortar with a moisture-retaining film or a damp cloth. The curing period should be no less than 7 days. During the curing period, avoid direct sunlight, rain and external force impact to ensure the steady growth of the mortar strength.
5. Precautions
The construction environment temperature should be between 5℃ and 35℃ to avoid low-temperature frost damage or rapid water loss at high temperatures. The selection of latex powder should match the repair requirements. For example, vinyl acetate-ethylene (VAE) type latex powder can be chosen for elastic repair, and acrylic type latex powder can be selected for weather-resistant repair.
Precise proportion table of redispersible polymer powder concrete repair mortar
(Prepared by mass ratio to suit different repair scenarios)
| Repair scene |
Cement
(P.O 42.5）
|
quartz sand (40-70 mesh) |
RDP |
HPMC |
water |
functional characteristics |
| Surface thin layer repair (thickness 2-5mm)） |
100 |
100 |
6-8 |
0.3-0.5 |
28-32
|
Strong adhesion, dense coating, and anti-sanding
|
| Moderate defect repair (thickness 5-20mm) |
100 |
200 |
4-6 |
0.2-0.3 |
26-30 |
High strength, good flexibility, suitable for cracks and pits
|
| Deep defect repair (thickness > 20mm) |
100 |
300 |
3-5 |
0.2 |
24-28
|
It has stable volume, is crack-resistant and suitable for large-scale deep repair |
Proportioning instructions
1. For redispersible polymer powder, VAE type (general-purpose type) or acrylic type (weather-resistant type) should be preferred. The specific choice should be adjusted according to the exposure environment of the repaired area.
2. Quartz sand must be clean and free of impurities. The particle size can be fine-tuned according to the thickness of the repair. For thin-layer repairs, finer 70-100 mesh sand can be selected.
3. When stirring, the dry powder components should be mixed evenly first, and then water should be added in several portions for stirring to ensure there are no lumps. The effect will be better if the mortar is stirred again after standing for 2 to 3 minutes.
Your message must be between 20-3,000 characters!
