Effects of Cement Slurry with the Addition of Cellulose Ethers on Ceramic Tile Bonding

 

Abstract: In the cement mortar, add different kinds of cellulose ethers to make the bonding paste. This paper studies the effects of the dosage for different kinds of cellulose ethers and the open time of slurry on the shear strength and tensile strength of ceramic tile bonding.

 

  1. Basic Principle of Bonding

The bond strength of ceramic tiles is usually represented by bonding shear strength and tensile strength. Johnpcook thought, “the total adhesive force of two kinds of materials glued together is equal to the sum of the special adhesive force and mechanical adhesive force”. The special adhesive force is a kind of chemical force, i.e., the molecular attraction between the two materials. The mechanical adhesive force is a kind of adhesive force caused by the chain reaction. The mechanical adhesive force has lower capacity to resist the external force, can resist the shear stress, and also plays some role when the bonding area is tensile. The special adhesive force, however, has resistance to the tensile, shear and peel force all. The shear strength is the most widely used and most valued test. It can test not only the special adhesive force, but also the mechanical adhesive force, closer to the falling-off behavior of tiles.

S.Semerdjiev proposed, “the bond strength depends on the strength of the binder itself (i.e., the cohesive force) and the adhesive force of the binder on the material”. For some kind of binder, its own strength is constant, but the adhesive force between it and different materials is varied. Generally speaking, the strength of the binder itself is always greater than the bond strength between it and other materials, so damage often occurs at the interface of the binder and the glued material. There are many factors affecting the adhesive force, such as the factors of the binder itself, the glued material factors, and the factors of usage conditions.

  1. I. Effects of Cellulose Ether Dosage and Open Time on the Bonding Shear Strength

The cellulose ether dosage and open time are quantitative influencing factors. Using the ceramic tiles with a water absorption of 9.4% and in the same experimental conditions, the bonding shear strength of different bonding slurry is tested, and the results are shown in Table 3. Conclusion: the bonding shear strength will be improved with the increase of cellulose ether dosage, but reduced with the prolongation of open time. The greater the dosage of cellulose ether is, the greater the effects of open time will be.

Table 3  Bonding Shear Strength of Different Slurry

No No Cellulose Ether Addition Amount (%) Open Time(min) Bonding Shear Strength (MPa) Failure Surface Compressive Strength (MPa)
1 O(0) HPMC 0 0 0.29 Ceramic Tile/ Slurry 50.8
2 E1(0) HPMC 0.1 0 0.97 Ceramic Tile/ Slurry 30.1
3 E2(0) HPMC 0.2 0 1.23 Ceramic Tile/ Slurry 16.6
3’ E2(0) HPMC 0.2 0 1.05 Ceramic Tile/ Slurry 12.5
4 E2(10) HPMC 0.2 10 1.12 Ceramic Tile/ Slurry 12.5
5 E2(20) HPMC 0.2 20 0.98 Ceramic Tile/ Slurry 12.5
6 E2(40) HPMC 0.2 40 0.53 Ceramic Tile/ Slurry 12.5
7 E2(60) HPMC 0.2 60 0.37 Ceramic Tile/ Slurry 12.5
8 E4(0) HPMC 0.4 0 1.39 Ceramic Tile/ Slurry 13.2
9 E’4(0) HPMC 0.4 40 0.99 Ceramic Tile/ Slurry 13.2
10 E6(0) HPMC 0.6 0 1.50 Ceramic Tile/ Slurry 11.1
11 E6(0) HPMC 0.6 10 1.37 Ceramic Tile/ Slurry 11.1
12 E6(20) HPMC 0.6 20 1.18 Ceramic Tile/ Slurry 11.1
13 E6(40) HPMC 0.6 40 0.78 Ceramic Tile/ Slurry 11.1
Note: the S/C of slurry = 1, the consistency of 6-8cm.
  1. II. Relationship between Compressive Strength and Bonding Shear Strength of Slurry

Generally speaking, the higher the compressive strength of cement mortar is, the higher the bond strength between it and other materials will also be. This study shows that the compressive strength of the cement slurry with the addition of cellulose ether is reduced, but the bond strength between it and ceramic tiles is increased. For the cement slurry with the addition of cellulose ether (using the same cement and sand), its compressive strength and bonding shear strength are in a linear inverse relationship.

III. Bonding Tensile Strength

The relationship between the bonding tensile strength of the slurry, with SIC = 1 and the consistency of 6-8cm, and the dosage of cellulose ether is shown in Table 4. As can be seen from the table, the bonding tensile strength is increased with the increase of cellulose ether dosage.

Table 4 Bonding Tensile Strength of Bonding Slurry

HPMC Dosage(%) 0 0.1 0.3 0.6
Bonding Tensile Strength( MPa) 0.16 0.42 0.65 0.86
  1. V. Conclusions
  2. Add the cellulose ether into the cement mortar to prepare into the bonding slurry. The bonding shear strength and bonding tensile strength between bonding slurry and ceramic tiles will be improved with the increase in the dosage of cellulose ethers, but reduced with the prolongation of open time. If cement and aggregates remain unchanged, for the bonding slurry made by changing cellulose ethers, its compressive strength and bonding shear strength are approximately in a linear inverse relationship.
  3. It has been confirmed by the X-ray method that after adding cellulose ethers into the cement mortar, the degree of hydration of the cement at the interface will be improved. It is found by observing the interface with a microscope the bonding between the slurry with the addition of cellulose ether and ceramic tiles has mainly improved the bond strength rather than the density.

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