The application of redispersible polymer powder in self-leveling mortar
Redispersible polymer powder is a core modified additive for self-leveling mortar, which can significantly enhance the flexibility, bonding strength, crack resistance and water resistance of the mortar.
In the self-leveling mortar system, its specific functions and application points are as follows:
- Enhance bonding performance
After film formation, it can form a firm bonding layer between the mortar and the base (such as concrete, tiles), avoiding the problems of hollowing and delamination that occur after the self-leveling mortar cures. It is especially suitable for the renovation of old floors or the leveling projects of different material bases.
- Enhance flexibility and crack resistance
The polymer film formed by latex powder can fill the internal pores of mortar, improve the brittleness of mortar, reduce the risk of cracking caused by temperature changes and base material shrinkage, and enhance the long-term stability of self-leveling floor.
- Optimize construction and usage performance
It can improve the thixotropy and water retention of mortar, reduce bleeding and settlement during construction, improve the leveling property of mortar, and make the surface smoother and flatter after molding. At the same time, it can enhance the wear resistance and impact resistance of hardened mortar.
- Application proportioning and selection
The commonly used types of redispersible latex powder are ethylene-vinyl acetate (EVA) copolymer and acrylate. The addition amount is generally 2% to 5% of the mass of the cementitious material, and the specific amount needs to be adjusted according to the target strength of the self-leveling mortar and the application scenario. For high humidity or outdoor scenarios, it is recommended to choose acrylate latex powder with excellent water resistance.
The following are three typical formulas of redispersible latex powder self-leveling mortar for mainstream scenarios (by weight, facilitating on-site proportioning and adjustment) :
1.General bedding type (100 parts dry powder, water-cement ratio approximately 0.22-0.25)
|
Component |
Dosage |
Explanation |
|
42.5R ordinary silica cement |
28 |
Basic gel |
|
High alumina cement CA-50 |
10 |
Fast setting and early strength |
|
70-140 mesh quartz sand |
41.11 |
The gradation is reasonable to ensure leveling and strength |
|
500-mesh heavy calcium powder |
16.2 |
Fill and optimize workability |
|
Hemihydrate gypsum + anhydrite |
7 (1+6） |
Adjust the setting time |
|
EVA/ acrylic latex powder |
1.5 |
Core modification enhances adhesion and crack resistance |
|
HPMC (200,000 viscosity） |
0.06 |
Retain water and prevent bleeding |
|
Polycarboxylate superplasticizer |
0.6 |
Increase flow and reduce the ash ratio of precipitation |
|
Defoamer |
0.2 |
Eliminate air bubbles and prevent surface pinholes |
|
Tartaric acid (retarding） |
0.18 |
Balance the setting of gypsum |
|
Lithium carbonate (promoting coagulation） |
0.15
|
Enhance early intensity
|
|
Slaked lime |
1 |
Auxiliary alkalinity regulation |
2.High crack resistance surface layer type (100 parts dry powder, water-cement ratio approximately 0.23-0.26)
|
Component |
dosage |
description |
|
42.5R ordinary silica cement |
32 |
high cementitious ratio |
|
High alumina cement |
8 |
early strength |
|
70-100 mesh quartz sand |
35 |
Smoother fine sand |
|
Silica fume |
3 |
dense internal structure and crack-resistant |
|
heavy calcium powder |
15 |
Filled |
|
Acrylate RDP |
2.5 |
better water resistance and crack resistance than EVA |
|
hpmc |
0.08 |
enhances water retention |
|
Polycarboxylate superplasticizer |
0.8 |
high fluidity |
|
Defoamer |
0.2 |
eliminates air bubbles |
|
retarder |
0.12 |
The construction window period |
|
Expansive agent |
0.3 |
compensates for shrinkage and prevents cracking |
3.Rapid Repair Type (100 parts dry powder, water-cement ratio approximately 0.20-0.22)
|
Component |
dosage |
description |
|
High alumina cement |
20 |
core fast setting early strength |
|
42.5R ordinary silica cement |
15 |
auxiliary strength |
|
80-120 mesh quartz sand |
45 |
graded sand |
|
heavy calcium powder |
12 |
filled |
|
Hemihydrate gypsum |
5 |
thickening time control agent |
|
Acrylic RDP |
2 |
compatible with the fast-setting system |
|
HPMC |
0.05 |
water retention |
|
Polycarboxylate superplasticizer |
0.7 |
flowing |
|
Defoamer |
0.2 |
eliminates air bubbles |
|
Lithium carbonate |
0.25 |
Strongly promotes coagulation, allowing people to walk on it within 24 hours |
|
Retarder |
0.1 |
balances the setting speed |
Key application points
- Latex powder selection: EVA is chosen for general scenarios, while acrylate is selected for high humidity/exposed scenarios. The addition amount is usually 1.5%-3% of the cementitious material, and can reach 5% for higher requirements.
- Mixing and application: Add water first, then dry powder, and stir at high speed for 2-3 minutes. The fluidity should be controlled at 160-180mm, and the construction thickness is preferably 3-10mm.
- Curing: After molding, cover with curing film to avoid strong winds and direct sunlight. At room temperature, it can bear a light load for 24 hours and reach the designed strength in 7 days.