Large-Format Ceramic Trend in Modern Architecture and Sectoral Challenges
Today's modern architecture and interior design trends increasingly lean toward larger-format ceramic and porcelain tiles to ensure aesthetic integrity and minimize grout lines. Thin porcelain slabs (sintered stones) in dimensions of 60x120 cm, 120x240 cm, and even larger have become standard beyond floor applications, extending to exterior facade cladding, bathroom walls, and various vertical surfaces. However, this aesthetic evolution has brought about a severe engineering problem for the construction chemicals sector: The slip issue of large-format tiles on vertical surfaces.
While traditional tile adhesive formulations possess rheological properties capable of supporting standard-sized tiles (e.g., 30x30 cm or 40x40 cm), they fall short when dealing with large-format tiles weighing 20-30 kilograms per square meter. The immense downward force generated by gravity exceeds the internal cohesion and holding power of the wet mortar, causing the tile to slide downward. This situation leads not only to aesthetic defects but also to increased labor costs, prolonged application times, and even occupational safety risks. At this point, rheology-modifying additives, specifically starch ethers, which fall within Ekvator Kimya's area of expertise, come into play.
C2T Class Tile Adhesives and the TS EN 12004 Standard
The performance of tile adhesives is classified under the European norm, the TS EN 12004 standard. For large and heavy tiles to be applied vertically, the adhesive must be at a minimum C2T (preferably C2TE or C2TE S1/S2) class. Each classification letter here denotes a specific performance:
- C (Cementitious): Cement-based adhesive.
- 2 (Improved): Improved, high adhesive strength (minimum 1.0 N/mm² tensile adhesion strength).
- T (Thixotropic / Reduced Slip): Reduced slip property, thixotropic character.
- E (Extended Open Time): Extended open time.
According to the slip test performed in accordance with the EN 1308 standard, a 'T' class adhesive must exhibit a slip amount of less than 0.5 mm. However, standard tests are typically conducted with 200-gram standard tiles. In contrast, the weight of large-format porcelain tiles applied in the field is manifold higher than this value. Therefore, R&D engineers designing a C2T class product must not only pass the standard but also develop formulations with ultra-high slip resistance suitable for field realities. The most efficient way to achieve this high performance is to design the correct cellulose ether and starch ether combination.
What is Starch Ether and How Does It Work?
Starch ethers are water-soluble polymers produced by chemically modifying starch obtained from natural botanical sources (potato, corn, tapioca, etc.). They are used in cement- and gypsum-based dry mortar systems at low dosages (typically between 0.01% and 0.05% of the total dry mix) to radically alter the rheological profile of the formulation. High-quality starch ethers such as Starvis SE, included in the Ekvator Kimya portfolio, offer unique advantages to construction chemicals manufacturers.
Rheology Modification and Thixotropic Gain
The primary function of starch ethers is to impart a strong thixotropic character to the mortar. Thixotropic behavior is the property of a fluid where its viscosity decreases (it becomes more fluid) under shear stress, and its viscosity rapidly recovers (solidifies) when the stress is removed. During the application process, this occurs as follows:
When the craftsman dips the trowel into the mortar and combs the surface, they apply a mechanical force (shear stress). The mortar containing starch ether decreases its resistance under this force, softens, and is spread easily without fatiguing the craftsman's arm (excellent workability). When the craftsman places the tile on the wall and presses it (removing the force), the polymeric network within the mortar recovers its original structure within seconds. The mortar reaches a yield stress high enough to support the weight of the tile. Thus, it resists the gravitational force of tons and prevents the tile from slipping even a millimeter.
Structural Synergy Between Cellulose Ethers and Starch Ethers
The use of cellulose ether (HPMC, MHEC, etc.) is mandatory in a tile adhesive formulation. Cellulose ethers increase the water retention capacity of the mortar to ensure cement hydration, extend the open time, and build basic viscosity. However, simply increasing the amount of cellulose ether is not the correct approach to prevent slip in large-format ceramics. Increasing the cellulose ether dosage beyond necessary levels causes excessive stickiness to the trowel, accelerates skinning time, and unnecessarily inflates costs.
This is where the remarkable synergy between starch ethers and cellulose ethers comes into play. Starch ethers penetrate the three-dimensional polymeric network formed by cellulose ethers, creating cross-links and hydrogen bonds. This interaction maximizes the internal cohesion of the mortar. The combined use of both polymers provides the following advantages:
- Zero Slip: Immediate vertical grip even on the heaviest tiles.
- Workability: Breaks the excessive stickiness caused by cellulose ether, allowing the mortar to release more easily from the trowel and preventing craftsman fatigue.
- Optimum Cost: Optimizes formulation costs by slightly reducing the usage amount of expensive cellulose ether with more cost-effective starch ether.
- Anti-Sagging: Prevents the mortar from sagging downward under its own weight, ensuring notched trowel marks remain upright and structured (stand-up property).
Starvis SE and Ekvator Kimya's Solution Approach
Overcoming the technical challenges posed by large-format ceramics is not possible with standard raw materials. As Ekvator Kimya, the Starvis SE series starch ethers, which we specifically developed/supplied for C2T and C2TE class tile adhesives, deliver results that satisfy manufacturers even under the most demanding site conditions.
Recipe Integration and Performance Optimization
A successful C2T formulation requires a flawless balance of all components (cement, calcite, sand, cellulose ether, redispersible polymer powder - RDP, and starch ether). Critical points to consider when integrating Starvis SE starch ether into the formulation include:
Dosage Adjustment: The efficacy of Starvis SE is very high. Proportions between 0.015% and 0.030% (based on dry weight) are generally sufficient to provide excellent slip resistance. Excessive usage may lead to excessive drying of the mortar and adversely affect the open time.
Compatibility with Polymer Powders (RDP): Flexibility and extra adhesive strength are required for the adhesion of large-format ceramics (especially low water absorption porcelains) to the surface. This is provided by Redispersible Polymer Powders (RDP). Starvis SE exhibits excellent chemical compatibility with the RDPs in the formulation, does not harm the polymer film formation process, and preserves tensile adhesion values at C2 standards.
Environmental Factors: Temperature fluctuations in the site environment directly affect the rheology of the mortar. Formulations stabilized with Starvis SE minimize viscosity loss even at high temperatures, ensuring that slip resistance remains sustainable.
Conclusion and Technical Support
The safe application of large-format ceramic and porcelain tiles on vertical surfaces has become both a prestige and a necessity for construction chemicals manufacturers. The most effective way to overcome this challenge, guarantee the T (Thixotropic) class in TS EN 12004 standards, and increase craftsman satisfaction is to integrate starch ethers with the correct specifications into formulations.
As Ekvator Kimya, we not only provide high-quality raw material supply but also offer formulation optimization support during laboratory and R&D stages. Our technical team is always by your side to determine how cellulose ether, RDP, and starch ether combinations will work with maximum efficiency in your recipe, to develop custom dosing strategies for you, and to optimize your production costs. To make a difference in the production of large-format tile adhesives and to access technical data sheets (TDS) for our Starvis SE product group, you can contact the Ekvator Kimya technical service.
