VAE polymer emulsion is a copolymer emulsion of vinyl acetate and ethylene. Due to the introduction of the comonomer ethylene, its internal plasticity is significantly improved. Therefore, VAE polymer emulsion has good film-forming properties, low film-forming temperature, soft and strong coating, and wear resistance, thus significantly improving the water resistance, alkali resistance, weather resistance and stain resistance of the coating. Choosing a VAE Emulsion (Vinyl Acetate–ethylene Copolymer Emulsion) with a lower viscosity can accommodate a large amount of filler while maintaining excellent adhesion to various substrates. This unique property makes it very suitable for adhesive materials where filler is used to control the bonding strength and cost.
1. Preparation of Waterproof Coatings
According to the technical requirements of the construction site, appropriate additives such as stabilizers, dispersants, and defoamers are added to the VAE emulsion. At the same time, some powders such as cement, calcium carbonate, and quartz powder are selected to design a variety of waterproof coatings that meet various technical requirements.
1.1 JS Waterproof Coating
Two-component water-based JS waterproof coatings, primarily composed of polymer emulsion and cement, come in two types: one uses cement entirely as filler, and the other uses a mixture of cement and other powders as filler. Both types of JS waterproof coatings form their films mainly through cement hydration and polymer particle dehydration and fusion. However, due to the difference in fillers, their film properties differ. Designing a formulation that meets both standards and engineering requirements generally uses the polymer-to-cement ratio (P/C) as the main parameter. Based on years of experimental experience, this paper discusses the formulation using aluminate cement and VAE emulsion as an example, using data and charts. Figure 1 shows the elongation at break of the coating with cement as the sole filler, as a function of P/C; Figure 2 shows the elongation at break of the coating with a mixture of cement and quartz powder as filler, as a function of P/C. Both coatings meet the tensile strength requirements of JC/T 894—2001 standard.
According to JC/T 894—2001, the range of design parameter P/C values that meet the performance index requirements of Type I and Type II JS waterproof coatings can be found in Figures 1 and 2, summarized in Table 1.
| Table 1. Design Parameters of JS Waterproof Coating P/C Value Range | ||
| Filler Type | Type I JS Waterproof Coating | Type II JS Waterproof Coating |
| Cement | 1.9-2.8 | 1.1-2.1 |
| Cement + Quartz Powder | 1.8-2.6 | 1.5-1.8 |
For JS waterproof coatings made entirely of cement, P/C can be considered as a design parameter. However, for JS waterproof coatings made by mixing cement and other fillers, in addition to P/C, the design parameters should also consider the polymer-to-powder ratio (P/F, the ratio of polymer mass to the total mass of powder) and the cement-to-powder ratio (C/F, the ratio of cement mass to the mass of other powders). The effects of P/F and C/F on the elongation at break of waterproof coatings with partial cement filler are shown in Figures 3 and 4, respectively.
Comparing Figures 3 and 4 with Figure 2, the effects of P/F and C/F on the elongation at break are clearly visible. Increasing the P/F value increases the elongation, while increasing the C/F value decreases the elongation. The abrupt change points on the P/F, C/F, and P/C curves are basically corresponding. Therefore, when designing JS waterproof coatings, it is necessary to comprehensively consider these parameters to obtain the optimal mixing ratio. In engineering applications, the following aspects need attention:
(1) When treating fine cracks and reinforcing layers, adding one layer of fiberglass cloth to the coating film can greatly improve the tensile strength of the film. Experiments show that, under the same raw material parameters, adding one layer of fiberglass cloth can increase the tensile strength of the coating film by 471%, while reducing the elongation at break by 99%.
(2) When it is necessary to increase the elongation at break of the coating film, an appropriate amount of plasticizer can be added, but this will result in a loss of tensile strength. For example, using the same formula, adding 12% plasticizer increases the elongation at break of the coating film by 93%, but reduces the tensile strength by 69%.
(3) When using cement to prepare JS waterproof coatings, adjusting the formula with P/C generally follows that as P/C increases, the tensile strength of the coating film decreases, while the elongation at break increases. However, this pattern applies within a certain P/C value range, and the P/C value range varies among different types of cement. Therefore, it needs to be determined through testing in application.
(4) The situation regarding the preparation of JS waterproof coatings using mixed powders is relatively complex. Analysis of the data in Table 2 shows that when P/F is the same, the tensile strength and elongation at break of the coating film are not significantly different; however, when P/C is the same but P/F is different, the coating film performance also differs.
| Table 2. Effects of P/C and P/F on Waterproof Coating Performance | |||
| P/C | P/F | Tensile Strength / MPa | Elongation at Break / % |
| 2.6 | 1.0 | 4.2 | 232 |
| 2.1 | 1.0 | 4.1 | 171 |
| 1.8 | 1.0 | 4.1 | 211 |
| 1.5 | 1.0 | 4.1 | 196 |
| 1.5 | 0.9 | 3.3 | 257 |
| 1.5 | 0.8 | 3.6 | 133 |
| 1.5 | 0.7 | 3.7 | 67 |
| 1.5 | 0.5 | 4.7 | 43 |
(5) When different types of cement are used with VAE emulsion to prepare waterproof coatings, even with the same mixing parameters, the differences in coating film performance are still significant. This should be given particular attention in engineering applications to avoid unnecessary losses.
1.2 Polymer Emulsion Waterproof Coatings
Using VAE emulsion as the main raw material, single-component water-emulsion type waterproof coatings can also be prepared. If colored pigments are added, the coating film, in addition to its waterproof function, also has the function of beautifying the environment. Formulation design and performance tests show that using VAE emulsion in combination with other emulsions effectively improves the tensile strength and elongation at break of the coating film, achieving better results than using VAE emulsion alone (such as VINAVIL EVA 2606L) .
with the same polymer-to-powder ratio (P/F), the composite emulsion waterproof coating exhibits superior performance. All indicators are more reasonable and meet the requirements of JC/T 864—2000 "Polymer Emulsion Waterproof Coatings for Buildings" standard. It should be noted that only one formulation ratio should be used in various projects; instead, the types and quantities of emulsion and powder should be adjusted according to the actual application areas to ensure the waterproof coating performance meets the requirements of different projects.
2. Preparation of Mortar Waterproofing Agents
Rigid waterproofing started with the five-layer plastering method, gradually progressing to the use of admixtures to modify cement mortar or concrete, and now to polymer-modified cement mortar. Compared with ordinary cement mortar, polymer-modified cement mortar has many superior properties, including strong adhesion, high elasticity, impact resistance, good waterproofing, and improved chemical resistance. The high bonding strength of VAE emulsion makes it very suitable for use in modified cement mortar.
When preparing waterproofing agents for cement mortar using VAE emulsion as the main material, it is important to note that: due to the large amount of calcium and magnesium ions in cement absorbing water from the emulsion, and the mechanical shearing action during mixing, the polymer emulsion may break down. To improve the stability of the emulsion, an appropriate amount of stabilizer should be added.
Experimental materials: self-made VAE waterproofing agent; cement, P·O 42.5 grade; sand, ISO standard sand.
Experimental mix ratio: m(cement):m(sand):m(VAE waterproofing agent) = 1:3:(0.47~0.52).
Experimental items: conducted according to JC/T 474—1999 "Waterproofing Agents for Mortar and Concrete", with particular attention to the change in water absorption over 48 hours (see Figure 5). The dosage of waterproofing agent in the mortar is expressed as the polymer-cement ratio P/C of the mortar.
As shown in Figure 5, the water absorption of VAE mortar decreases rapidly when P/C = 0.15~0.19, and then the rate of decrease slows down as the P/C value increases.
Performance testing was conducted on VAE mortar with a P/C value of 0.2, and the results are shown in Table 4.
| Table 4 Main performance indicators of VAE mortar | ||||
| 7-day compressive strength ratio % | 28-day compressive strength ratio % | Water permeability ratio 1% | 48-hour water absorption ratio % | 28-day shrinkage ratio % |
| 143 | 136 | 375 | 9 | 107 |
Characteristics of VAE waterproofing agent applied to cement (mortar):
(1) Water reduction rate can reach over 30%, thus increasing mortar density, reducing and uniformly distributing internal voids, and increasing compressive strength.
(2) Significantly reduced water absorption and excellent waterproofing properties, making it very suitable for constructing water storage tanks, underground projects, roofs, and other waterproofing facilities.
(3) When VAE waterproofing agent is mixed with mortar, the workability of the mortar is good, the water retention is improved, and bleeding is effectively prevented.
(4) Cement (mortar) mixed with VAE waterproofing agent has high bonding strength and can be used as a binder for various building materials.
(5) In engineering practice, cement (mortar) modified with VAE waterproofing agent exhibits excellent anti-seepage and waterproofing performance. Whether used as a waterproofing finishing material on the water-facing or backwater side of water-retaining structures, or for repairing leaking rigid waterproofing layers, VAE waterproofing agent has been rapidly promoted and applied due to its suitability for construction on damp substrates.
3 Conclusion
Years of research and application have proven that VAE emulsion (such as VINNAPAS EP 4600) used in polymer-modified cement (mortar) products exhibits unique properties, possessing both high bonding strength and tensile strength, as well as good elongation. This performance is crucial for polymer-modified cement (mortar) products. VAE emulsion-modified cement (mortar) has broad practical value in concrete repair, protection, waterproofing, corrosion prevention, and bonding.
Website: www.elephchem.com
Whatsapp: (+)86 13851435272
E-mail: admin@elephchem.com
Soporta red IPv6
