NEW STANDARDS MAKE GREATER DEMANDS The impact of the new EN 12004 standard on formulation technology and raw materials for cement-based tile adhesives D. Zweife Zweifel, l, R. Baumann Baumann,, U.Trib U.Tribelh elhorn orn
New Standards Make Greater Demands
The impact of the new EN 12004 standard on formulation technology and raw materials for cement-based tile adhesives D. Zweifel, R. Baumann, U.Tribelhorn
Contents Background Euronorm 12004 – A Synopsis Summarised results Proceeding Step by Step Cement Sand Cellulose ethers Alternative thickener systems Redispersible polymer powders Concrete slabs and tiles Formulations for EN 12004 Experimental Test methods
New Standards Make Greater Demands
The impact of the new EN 12004 standard on formulation technology and raw materials for cement-based tile adhesives D. Zweifel, R. Baumann, U.Tribelhorn
1
The introduction of the new EN standards for cement-based tile adhesives, a product for which Dow supplies METHOCEL* cellulose ethers and DOW Latex Powders, is making new demands on tile adhesive producers. Standardisation of the norms involves more stringent testing, as well as specific classifications for different tile adhesive qualities, which results in a real challenge in meeting the standards. Included in the EN 12004 standard are two cement-based tile adhesive classifications: C1 which outlines general requirements, and C2 which describes improved or additional characteristics.These set out the minimum requirements for improved adhesion after 28 days at room temperature and under heat, water and freeze/thaw storage conditions. They also stipulate optional requirements for fast setting, reduced slip and extended open time. Sand and cement are the main constituents of cement-bonded, thin-bed adhesives and determine the properties to a large extent. However, no tile adhesive which can be applied by the thin-bed procedure is formulated with sand and cement alone. Numerous additives enable an endless range of variations in processing and end properties to satisfy the wishes of the end user. The need to be able to compare and to classify this enormous variety of products has existed for a long time. «Flexible adhesive», «standard adhesive» and «fluidized bed *Trademark of the Dow Chemical Company
mortar» are all examples of attempts to categorise these products. However, it has often been the case that each region, each country or even each manufacturer, used different terminology.After much debate, the initiative for the regulation of adhesive mortars was finally agreed earlier this year, and with EN 12004 coming into effect, the quality requirements for cement-based tile adhesives will now be standardised Europe-wide, replacing conflicting national standards. The tile adhesive formulator is therefore faced with a stiff challenge – that of demonstrating that his products match the new standards in test conditions. In order to support their customers, the Dow METHOCEL and DLP technical experts have carried out a study to quantify the influence of the numerous variables of tile adhesives.This knowledge should aid the formulator to develop tile adhesives that satisfy the requirements according to EN 12004 (C1 and C2).
Making Sense of Euronorm EN 12004 – A Synopsis
The aim of the study is to provide you with data and guidelines to assist you when carrying out tests on cement-based tile adhesives in relation to compliance with EN 12004.
2
The following table (Page 2) provides an overview of the requirements per classification of cementbased tile adhesives. The general classifications C1 and C2 can be combined with additional requirements (F,T, E). Designations like C1T or C2TE clearly describe the properties of cement-based tile adhesives. Rapid hardening adhesives (F) were not a subject of this study.The freeze-thaw cycle was also omitted, as manually executed freeze – thaw yields results with limited reproducibility.
Test method
The results of studies relating to EN 12004 depend not only on the adhesive being tested, but also strongly on the type of tiles and concrete slabs used.This fact must be taken into consideration with regard to the «absoluteness» of the test results. Obviously the materials used for the tests should meet the specifications required by the norms. It is relatively simple to formulate an adhesive which meets the C1 requirement. It is not a great obstacle to reach the required 0.5 N/mm2, but the challenge is rather that of keeping the cost as low as possible. Aiming to omit the polymer powder from the formulation would be attractive from an economical point of view but would fail, in our
Test class C1
experience, because of insufficient adhesion after heat aging.The quantity of polymer powder can be reduced when cement of higher quality is used (Table 1). It is far more difficult to formulate tile adhesives meeting the C2 classification. Tensile adhesion requirements of >1.0 N/mm2 represent quite a challenge. The results of our studies allow the following conclusions to be drawn: • The tensile adhesion strength can be improved by the use of higher quality cements. An important fact to be taken into consideration is that the increase in tensile adhesion, after water immersion or after heat aging, increases disproportionately.
Test class C2
Normal setting adhesives
Open time EN 1346
≥
0.5 N/mm2 after 20 min
≥
0.5 N/mm2 after 20 min
Tensile adhesion strength EN 1348
≥
0.5 N/mm2
≥
1.0 N/mm2
Water immersion EN 1348
≥
0.5 N/mm2
≥
1.0 N/mm2
Heat aging EN 1348
≥
0.5 N/mm2
≥
1.0 N/mm2
Freeze-thaw cycle EN 1348
≥
0.5 N/mm2
≥
1.0 N/mm2
≥
0.5 N/mm2 after 24 hours
≥
0.5 N/mm2 after 24 hours
≥
0.5 N/mm2 after 10 min
≥
0.5 N/mm2 after 10 min
≤
0.5 mm
≤
0.5 mm
≥
0.5 N/mm2 after 30 min
Fast setting adhesives F: Rapid hardening and
Open time (EN 1346) Additional requirements T: Slip E: Extended open time
Note: Please refer to the original Std. EN 12004 as reference.This is just an interpretation by Dow.
Making Sense of Euronorm EN 12004 – A Synopsis
• Lightly modified cellulose ethers have limited slip resistance and a reduced water demand but show their advantage in the tensile adhesion after water immersion and heat aging. • The loss in slip resistance can be compensated by means of sheet silicates and/or cellulose fibres. The improvement in slip resistance is often reached without a compromise in tensile adhesion strength.
3
• By optimising the cellulose ether it is possible to develop slip resistant adhesives (slip <0.5 mm) which yield remarkable tensile adhesion strength with a DLP 2000 addition level of only 1% and 3% (see Formulations 40 and 41). • By selectively adjusting the polymer powder addition level it is possible to develop tile adhesives meeting either C1 or C2 classification.The newly developed polymer powder DLP 2000 will yield extremely high tensile adhesion strength. If the formulation is optimised just to meet minimum requirements, then these properties can be met with a relatively low addition level of DLP 2000. This clearly has a positive effect on the costs. A reduction in the addition level from 4 to 3% or 2 to 1% respectively would result in a reduction in cost of 10% to 15% of the total formulation.
Summary of study results
The conclusions of the study are summarised in the above figure. The effect that each of the investigation parameters has on the final properties is shown as an arrow pointing in the influencing direction.
Proceeding step by step Cement
In order to quantify the effect of the individual components of tile adhesives on its processing and end properties, it is appropriate, given the large number of additives, to proceed step by step and ingredient by ingredient.
Parts of the work were done utilising computer-aided statistically designed experiment planning and evaluation.
5
Portland cement is available in many quality classifications. Depending on the particle size and the chemical composition of the clinker, concrete with different compressive strength values is obtained. Fine particles will hydrate better, thus yielding higher strength values.This effect can also be observed in cementbased tile adhesives as the following table demonstrates:
Portland cement quality from CEM I 42.5 to CEM I 52.5, the standard tensile adhesion improved only slightly, by an average of 0.2 N/mm2. Comparing the tensile adhesion results in the same set of tests, after 20 minutes and 30 minutes open time, no difference can be determined.
proven that the tensile adhesion, after these two aging procedures, are the most critical properties in order to meet EN 12004 requirements. Surprisingly the nominal improvement of the tensile adhesion is independent of the redispersible polymer powder level, which means that the increase in tensile adhesion strength which is influenced by the cement quality, is the same for both the formulations containing 1% DLP 2000 and 3% DLP 2000.
Results: The influence of the Portland cement quality on the tensile adhesion results is not so evident in all tests. Changing the
Results obtained after the water immersion test (+0.3 N/mm2) and after heat aging (+0.5 N/mm2) demonstrate that the use of better quality Portland cement can be advantageous. Practice has
Components
Formulation 1
Formulation 2
Formulation 3
Formulation 4
60
60
60
Steidle sand
Wt.-%
60
CEM I 42.5
Wt.-%
40
CEM I 52.5
Wt.-%
XCS 41120.00
Wt.-%
0.4
0.4
0.4
0.4
DLP 2000
Wt.-%
1.0
1.0
3.0
3.0
Wt.-%
1.0
1.0
1.0
1.0
Arbocell BWW40 2)
Wt.-%
0.5
0.5
0.5
0.5
Water
Wt.-%
32
31
31
30
mm
2.0
2.0
4.0
3.0
Bentone GS
1)
40 40
40
Properties
Slip
Tensile adhesion strength
Standard
N/mm2
0.88
1.05
1.39
1.56
20 min open time
N/mm2
0.86
1.02
1.39
1.34
Water immersion
N/mm2
0.70
1.02
0.69
1.01
Heat aging
N/mm
0.15
0.65
1.00
1.50
2
Table 1: Comparison of two different cement qualities with two different DLP 2000 levels
1) Trademark of Rheox Europe S. A. Bruxelles 2) Trademark of Rettenmaier & S öhne, Ellwangen
Proceeding step by step Sand
6
Because of the relatively high transport costs, the choice of sand remains limited to local sand supplies. Nevertheless, it makes sense to investigate the influence of the sand quality on the application and final properties of tile adhesives. In our studies we limited the number of sands to two very different types. Zimmerli sand is a highly refined quality with a rather narrow particle size distribution (0.1 – 0.3 mm) and a very low specific surface (< 0.1 m2/g ). In contrast, Steidle sand has a broader particle size distribution (0 – 0.45
mm) and a substantially higher specific surface (~ 2.9 m2/g).
Ground limestone (~60 µm) is often added to the formulation as a fine filler to improve the application properties and a better optical appearance of the liquid mortar. Formulation 7 (table 2) proves that the use of ground limestone in moderate amounts does not harm the end properties of a tile adhesive. Excessive amounts of ground limestone, however, have a detrimental effect on open time.
Results: Comparing the two formulations, where only the sand quality was altered, shows that the properties obtained are almost identical. Sand has the function of a filler in a tile adhesive formulation. It is therefore to be expected that the influence on the tensile adhesion strength remains low. The sand with the higher specific surface required two parts more water in order to maintain the same slip and consistency.
Components
Formulation 5
Formulation 6
60
Formulation 7
Steidle sand
Wt.-%
55
Zimmerli sand
Wt.-%
Limestone 60 µm
Wt.-%
CEM I 52.5
Wt.-%
40
40
40
METHOCEL 10-0350
Wt.-%
0.5
0.5
0.5
DLP 2000
Wt.-%
2.0
2.0
2.0
Water
Wt.-%
28
26
28
BF 0.5 rpm
mPa·s
3,971,000
3,793,000
4,298,000
BF 5.0 rpm
mPa·s
557,000
528,000
570,000
BF 50 rpm
mPa·s
91,000
84,000
94,000
Slip
mm
0.5
0.5
0.5
60 5
Properties Rheology
Tensile adhesion strength
Standard
N/mm2
1.16
1.19
1.08
20 min open time
2
N/mm
1.56
1.59
1.59
30 min open time
N/mm2
1.03
1.27
1.02
Water immersion
N/mm2
0.43
0.61
0.54
Heat aging
N/mm2
0.94
1.00
0.87
Table 2: Different sand qualities in tile adhesive formulations
Proceeding step by step Cellulose ethers
Cellulose ethers are among the most important additives in a tile adhesive formulation.These additives substantially affect application and end properties. Cellulose ethers are not only thickeners, controlling water demand and water retention, but also through the degree of modification and their rheological effect, they determine the tensile adhesion strength, slip resistance, open time and application properties.
7
The following table demonstrates the influence of different cellulose ether types on the properties of a tile adhesive. Results: METHOCEL 10-0356 is a modified cellullose ether with a
Components
pronounced thickening effect. METHOCEL 10-0350 has a comparable viscosity (~10 000 mPa·s) mode-rately modified, and experimental celluose ether XCS 41120.00 is even less modified. In the test series (Table 3) the water level was adjusted in order to obtain approx. 400 000 mPa·s (5.0 rpm). Depending on the degree of modification the water demand changed accordingly.The slip resistance decreases with water demand, which can be explained by the lower structural viscosity of the liquid mortar. The structural viscosity is a measure of how much the viscosity decreases with increasing shear rate. As a measure of the structural viscosity, the difference of the logarithm of the viscosity
determined at 0.5rpm and 50rpm, is used.With the exception of the results after hot aging, the tensile adhesion results are comparable. Reducing the degree of modification appears to have a positive effect on the tensile adhesion after heat aging. The tensile adhesion after heat aging represents in many cases the most critical obstacle to fulfilling EN 12004.The slip resistance and the water demand are negatively influenced by a lower degree of modification. One way out of this dilemma would be an additive that increases the water demand and slip resistance, without having a negative impact on tensile adhesion, especially after hot aging.
Formulation 8
Formulation 9
Formulation 10
Zimmerli sand
Wt.-%
60
60
60
CEM I 42.5
Wt.-%
40
40
40
METHOCEL 10-0356
Wt.-%
0.4
METHOCEL 10-0350
Wt.-%
XCS 41120.00
Wt.-%
DLP 210
Wt.-%
4.0
4.0
4.0
Water
Wt.-%
28
26
25
BF 0.5 rpm
mPa·s
3,750,000
2,780,000
2,100,000
BF 5.0 rpm
mPa·s
416,000
396,000
384,000
BF 50 rpm
mPa·s
55,000
76,000
76,000
1.83
1.56
1.45
mm
0.5
1.5
2.0
Standard
N/mm2
1.25
1.32
1.45
20 min open time
N/mm2
1.19
1.35
1.25
30 min open time
N/mm2
0.69
0.72
0.75
Water immersion
N/mm2
0.68
0.73
0.76
Heat aging
N/mm2
0.34
0.58
0.80
0.4 0.4
Properties Rheology
log (0.5 rpm) – log (50 rpm) Slip Tensile adhesion strength
Table 3: Property profile of cellulose ethers in cement based tile adhesives
Proceeding step by step Alternative tickener systems
It was found that other, non water-soluble thickeners increase the consistency of cement-based tile adhesives, without negative consequence on the tensile adhesion. Sheet-silicates and cellulose fibres are such products.
mulation with the aid of sheet silicates (Pangel S-9) or cellulose fibres (Arbocel BWW 40) without reducing the slip resistance. Even more important is the fact that the tensile adhesion does not deteriorate by the addition of these types of additives.
Results: Table 4 clearly demonstrates that it is possible to increase the water demand of a tile adhesive for-
8
Components
Formulation 11
Formulation 12
Formulation 13
Steidle sand
Wt.-%
60
60
60
CEM I 52.5
Wt.-%
40
40
40
METHOCEL 10-0350
Wt.-%
0.5
0.5
0.5
Pangel S-9 3)
Wt.-%
Arbocell BWW 40
Wt.-%
DLP 2000
Wt.-%
2.0
2.0
2.0
Water
Wt.-%
28
32
32
BF 0.5 rpm
mPa·s
3,790,000
3,201,000
2,960,000
BF 5.0 rpm
mPa·s
594,000
464,000
436,000
BF 50 rpm
mPa·s
96,000
79,000
73,000
Slip
mm
1.0
0.75
1.0
0.5 0.5
Properties Rheology
Tensile adhesion strength
Standard
N/mm2
1.19
1.31
1.20
20 min open time
2
N/mm
1.69
1.44
1.35
30 min open time
N/mm2
1.27
1.10
1.28
Water immersion
N/mm2
0.85
0.96
1.01
Heat aging
N/mm2
0.89
1.22
1.21
Table 4: Alternative thickeners for cement-based tile adhesives
3) Trademark – Grupo Tolsa, Madrid
Proceeding step by step Alternative tickener systems
Results: Bentone GS, a hectorite and Optibent CP, a bentonite, have nearly the same effect on the tensile adhesion properties. Optibent CP increases the viscosity to a lesser degree than Bentone GS. Attapulgites, such as Minugel 200 increase the consistency, but they have a negative influence on tensile adhesion properties. In particular,
Components
9
the open time and the adhesion after the heat aging deteriorate. Pangel S9, a sepiolite has proven to be most effective.The thickening effect is twice as efficient as hectorite or bentonite. In practice this means that only half the dosage level is required to reach the same viscosity.The tensile adhesion is not influenced and remains high.
Formulation 14 Formulation 15 Formulation 16 Formulation 17
Steidle sand
Wt.-%
60
60
60
60
CEM I 42.5
Wt.-%
40
40
40
40
XCS 41120.00
Wt.-%
0.4
0.4
0.4
0.4
DLP 210
Wt.-%
4.0
4.0
4.0
4.0
Bentone GS
Wt.-%
1.0
Minugel 200 4)
Wt.-%
Optibent CP
5)
1.0
Wt.-%
1.0
Pangel S-9
Wt.-%
0.5
Water
Wt.-%
28
28
28
28
BF 0.5 rpm
mPa·s
3,600,000
3,974,000
2,690,000
3,290,000
BF 5.0 rpm
mPa·s
528,000
598,000
478,000
440,000
BF 50 rpm
mPa·s
93,000
100,000
85,000
77,000
Slip
mm
1.0
1.0
1.0
0.5
Properties Rheology
Tensile adhesion strength
20 min open time
N/mm2
1.95
1.41
1.90
1.32
30 min open time
2
N/mm
0.99
0.48
1.07
0.94
Water immersion
N/mm2
0.84
0.74
0.85
0.81
Heat aging
N/mm2
0.90
0.64
0.94
0.79
Table 5:The effects of different sheet silicates on the properties of a tile adhesive.
4) Trademark of ITC, Inc. Maryland, USA 5) Trademark of Südchemie AG, Munich
Proceeding step by step Redispersible polymer powder
Redispersible polymer powders are crucial components of high quality tile adhesive formulations.These additives substantially increase the tensile adhesion and improve the flexibility of the adhesive link between the tile and the substrate. This feature is very important especially with difficult substrates like wood, old tiles and when floors are equipped with floor heating. Redispersible polymer powders also play a key role in tile adhesives meeting EN 12004.
10
Results: A rather simple base formulation with a low water demand was used.This explains the relatively low tensile adhesion values obtained. However, the influence an increased powder level has on the properties in other formulations, can be estimated accordingly. Without addition of polymer powders the tensile adhesion after heat aging has almost completely collapsed.The standard tensile adhesion, as well as the tensile adhesion after heat aging, improves when the level of polymer powder is increased.This effect is more pronounced with DLP 2000.
The figure below illustrates the effect of two different polymer powders on the tensile adhesion properties of a tile adhesive. Both products are vinyl acetate/ethylene based. However, DLP 2000 is a harder polymer with a higher glass transition temperature than DLP 210.
When cement of better quality is used or if other rheological additives (sheet silicates, cellulose fibres) are added to increase the water demand it is possible to achieve tensile adhesion values with DLP
DLP 210
2000, which fulfill the requirements of EN 12004/C2. As demonstrated in the previous simple formulation, here too in Figure 2 an increase in the polymer powder addition level shows a clear improvement in the standard tensile adhesion, as well as in the tensile adhesion after heat aging. Apparently, the addition level of polymer powder has no influence on the tensile adhesion after water immersion. In this formulation the addition of only 2% of DLP 2000 is sufficient to achieve a tensile adhesion of 1.0 N/mm2 after standard, wet and heat aging. Figure 3 shows the results of deformation measurements of cured adhesive strips according to EN 12002. It is remarkable to see that the maximum transversal deformation more than doubles with the
DLP 2000
2.5
2
2
m m / N , 1.5 n o i s e h d 1 a e l i s n e 0.5 T
Standard Heat aging Water imm. Base formulation: Zimmerli-Sand CEM I 42.5 XCS 41120.00 Water
0 w/o
2%
4%
6% DLP
2%
4%
Figure 1: Comparison of two DLP products in a tile adhesive formulation at two addition levels.
6%
60.00 Wt. – % 40.00 Wt. – % 0.45 Wt. – % 25.00 Wt. – %
Proceeding step by step Redispersible polymer powder
1.8
11
] 2 m1.6 m / N [ 1.4 , h t g 1.2 n e r t s 1 n o i s 0.8 e h d a 0.6 e l i s n 0.4 e T
Base formulation
1% DLP 2000
Steidle sand
60.0 Wt. – %
CEM I 52.5
40.0 Wt. – %
2% DLP 2000 3% DLP 2000
XCS 41120.00
0.4 Wt. – %
1.0 Wt. – % Arbocell BWW40 1.5 Wt. – % Bentone GS
0.2 0
Standard
Water immersion
Heat aging
Figure 2: Influence of addition level on tensile adhesion
Deformation with different Polymer powders according to EN 12002 10 Deformation (L) Force (F)
) m m ) ( n N o ( i t e 5 a c r o m r F o f e D
Base formulation Zimmerli sand 60 CEM I 42.5 40 10-0366 0.45 Polymer powder 0-6 Water 25
Wt. – % Wt. – % Wt. – % Wt. – % Wt. – %
0 0% DLP 210
2% DLP 210
4% DLP 210
6% DLP 210
2% DLP 2000
4% DLP 2000
6% DLP 2000
Polymer powder type and addition level
Figure 3: Maximum transversal deformation and maximum force of a tile adhesive formulation containing two different types of polymer powders
Proceeding step by step Redispersible polymer powder
increasing polymer powder level, whereas the maximum force remains at a similar level. The performance with regard to maximum deformation and force of DLP 210 and DLP 2000 are very similar.
The choice of the optimum polymer powder is important to the overall performance of the tile adhesive such as open time, standard tensile adhesion, tensile adhesion after specified aging procedures, and rheological properties. Depending on the property profile desired,
which also depends on the other components of the formulation (e.g. sand, cement, cellulose ether), the redispersible polymer powder must be carefully selected to fit the formulation.
Application properties of different polymer powders Components
12
Formulation 26
Formulation 27
Formulation 28
Formulation 29
CEM 42.5
Wt.-%
40
40
40
40
Steidle sand
Wt.-%
60
60
60
60
10-0350
Wt.-%
0.5
0.5
0.5
0.5
Std.VA / E Type
Wt.-%
3
DLP110
Wt.-%
DLP210
Wt.-%
DLP 2000
Wt.-%
Water
Wt.-%
28
28
28
28
kg/m3
1543
1462
1500
1537
BF 0.5 rpm
mPa·s
3,132,000
3,713,000
3,324,000
3,587,000
BF 5 rpm
mPa·s
445,000
457,000
453,000
467,000
BF 50 rpm
mPa·s
71,000
77,000
74,000
75,000
Slip
mm
1.2
1.5
1.6
1.0
3 3 3
Properties
Density Rheology
Tensile adhesion strength
Standard
N/mm2
1.21
1.47
1.04
1.20
10 min open time
2
N/mm
1.70
1.83
1.73
1.96
30 min open time
N/mm2
1.54
1.18
1.38
1.92
Heat aging
N/mm2
0.57
0.39
0.38
0.74
Water immersion
N/mm2
0.18
0.79
0.67
0.69
Table 6: Comparison of different polymer powders
Proceeding step by step Redispersible polymer powder
Identification
Flexibility
Tg (C)
MFT
Std.VA / E type
Wt.-%
VA/E
Hard
17
0
DLP 110
Wt.-%
VA/Veova
Hard
22
4
DLP 210
Wt.-%
VA/E
Soft
6
0
DLP 2000
Wt.-%
VA/E
Medium hard
17
3
VA: Vinyl acetate
13
Polymer base
E: Ethylene
VeoVa: Vinyl ester of versatic acid
Table 6 shows the properties of different redispersible polymer powders in a standard tile adhesive formulation. DLP 110, a relatively hard VA/VeoVa grade proves its advantage in the standard tensile adhesion and in the tensile adhesion after water immersion.The tensile adhesion after 30 min open time is lower compared with other polymers.VA/VeoVa polymers tend to show skin formation after a longer open time. The standard VA/E copolymer shows a balanced standard tensile strength and open time properties. However
the tensile strength after water immersion is lower (0.18 N/mm2) compared with all other polymers used.The tensile strength of DLP 210 is somewhat lower after heat aging compared to the Std.VA/E copolymer. After the water immersion, however, it is clearly better (0.67 N/mm2).The medium hard DLP 2000 shows a very balanced performance between standard tensile adhesion, open time and adhesion after heat aging and water immersion. It outperforms all other polymers tested in most of the properties.
Proceeding step by step Concrete slabs and tiles
The test results obtained do not only depend on the composition of the tile adhesive, but also on the quality of the substrate, namely the concrete slabs and the tiles onto which the adhesive is applied.The quality of the concrete slabs depends on various parameters like the nature of the surface, the absorption behaviour and the thermal expansion coefficient. EN 1323 specifies water absorption limits of 0.5 – 1.5 ml within the first
4 hours. For practical and economical reasons, commercially available concrete slabs are used for testing. Slabs fulfilling EN 1323 requirements are not available at reasonable cost. For the study, we had two qualities of concrete slab at our disposal. Neither of the slabs fulfills the EN
1323 requirement of 0.5 – 1.5 ml water absorption. Slab A absorbs substantially more water, whereas slab B absorbs practically no water. This behaviour has serious consequences for the tensile adhesion results obtained, as the following table demonstrates.
Water absorption according to EN 1323
Slab A
2.0 – 3.5 ml
Slab B
0.05 – 0.20 ml
14 Components
Formulation 30
Formulation 31
Formulation 32
Formulation 33
Concrete slab
A
B
A
B
CEM 42.5
Wt.-%
40
40
40
40
Zimmerli sand
Wt.-%
60
60
60
60
METHOCEL 345
Wt.-%
0.5
0.5
10-0350
Wt.-%
0.5
0.5
DLP 210
Wt.-%
2
2
Water
Wt.-%
28
28
28
28
BF 0.5 rpm
mPa·s
2,112,000
2,112,000
3,511,000
3,511,000
BF 5 rpm
mPa·s
465,000
465,000
447,000
447,000
BF 50 rpm
mPa·s
101,000
101,000
71,000
71,000
Properties Rheology
Tensile adhesion strength
10 min open time
N/mm2
1.08
1.56
1.06
1.49
30 min open time
N/mm2
0.10
0.36
0.92
1.45
Heat aging
N/mm2
0.10
0.80
0.43
0.94
Water immersion
N/mm
0.86
0.90
0.82
0.94
2
Table 7: Tensile adhesion strength obtained with two types of concrete slabs
Proceeding step by step Concrete slabs and tiles
15
Results: The tensile adhesion results obtained with the more absorbing concrete slabs (A) are in this case lower than with the less absorbing concrete slabs (B). Only the values obtained after the water immersion remain independent of water absorption.The largest difference in the results obtained with the two different slabs was in tensile adhesion strength after heat aging, where values varied by a factor of two to eight. Hence a correlation between water absorption and tensile adhesion strength could be established.
The difference in the results obtained after 10 and 30 minutes open
time can be explained by the lack of water retention.The adhesive applied onto the more absorbent concrete slab dries out more until the tile is inserted.The differences obtained after heat aging are difficult to estimate and are therefore the subject of further investigation.The test results of formulation 30/31 demonstrates that the C1 classification can also be met without redispersible polymer powder depending on the substrate used (heat aging value). In all our studies we used concrete slab type A. Even though it does not meet the EN 1323 requirements, the slab yielded reproducible results.
Components
Form 34 Form 35
The fact, that the results with these slabs were lower, only indicates tougher test conditions, which should not diminish the quality of the work described. The quality of the tiles influences the performance of a tile adhesive in a similar way to that already seen with the concrete slabs. In the following table the influence of fully vitrified tiles and porous tiles (from two different tile producers), on the tensile adhesion, is demonstrated. The data show the influence of different tile types on the adhesion performance using two different tile adhesive formulations.A rather simple tile adhesive formulation
Form 36
Form 37
Form 38 Form 39
CEM 42.5
Wt.-%
40
40
40
40
40
40
Steidle sand
Wt.-%
60
60
60
60
60
60
METHOCEL 267
Wt.-%
0.5
0.5
0.5
METHOCEL 10-0350
Wt.-%
0.5
0.5
0.5
Water
Wt.-%
30
30
30
30
30
30
Tile type: X
Porous tile, EN 159
Fully vitrified French tile, EN 176
X X
X
X
Fully vitrified German tile, EN 176
X
Properties Tensile adhesion strength
10 min open time
N/mm2
1.32
0.91
1.16
1.34
0.93
1.09
30 min open time
N/mm2
0.54
0.39
0.62
0.70
0.52
0.67
Heat aging
N/mm2
0.46
0.07
0.11
0.38
0.00
0.03
Water immersion
N/mm
1.15
0.70
1.16
1.07
0.67
1.08
Table 8: Comparison of different tiles
2
Proceeding step by step Concrete slabs and tiles
based on CEM I 42.5 and two different types of cellulose ether were compared. None of these formulations contain polymer powder.
16
The influence of tile quality on adhesion was most pronounced after heat aging.The tensile adhesion obtained with the porous tile was 0.46 N/mm2 and 0.38 N/mm2, where as a tensile adhesion of only 0.07 N/mm2 was obtained with the fully vitrified (EN 176) tile from France. Tensile adhesion using the second formulation was totally lost. The fully vitrified German tile (EN 176), showed only marginally better performance after the heat aging. However, the open time and the tensile adhesion after water immersion with this tile were similar to the results of the porous tile and clearly better than the results obtained with the fully vitrified French tile.This demonstrates that different adhesion performance results can be obtained with different tiles, meeting the same norm (EN 176).Why such differences arise may depend, for instance, on the porosity, surface nature, or on the thermal behaviour. In order to keep conditions constant we only used the French fully vitrified tiles for all our studies according to EN 1348.
Development of formulations for the EN 12004 classification
The purpose of this part of the study was to optimise tile adhesive formulations to meet a C1T/C2TE classification as cost effectively as possible.With the help of a computer aided experimental design software program (JMP) the influence of the following parameters were investigated: nominal viscosity of the cellulose ether, degree of modification as well as addition level of cellulose ether and polymer powder.
Results:The results from this evaluation allow the following conclusions, which could be specific to the raw materials used (Steidle sand, CEM I 52.5):
The low viscosity cellulose ether (4000 mPa·s) has an advantage in open time, where the tensile adhesion was more than 40% higher. A cellulose ether concentration of 0.4% also yielded improved adhesion after heat aging (+15%).
A medium to strong modification of the cellulose ether improves the open time particularly.The latter also has a strong influence on the water demand, which can be increased by 3% whilst maintaining the slip resistance.The addition level of DLP 2000 has a great influence on the adhesion results after heat aging.
17 Impact of formulations parameters on the properties of the tile adhesive: Formulation parameters Adhesives properties
CE-Viscosity
CE-Dosage
Water demand Standard adhesion 20 min open time 30 min open time Heat aging
Water immersion
Table 9: Dependence of the variables as calculated by JMP
CEModification
DLP 2000 Dosage
Development of formulations for the EN 12004 classification
The water level can also be reduced by 1% with every additional 1% of DLP 2000 whilst maintaining the same slip resistance.
18
As a result of the experimental design an optimum formulation (Table10, Formulation 40), can be developed meeting the C1T classification e.g. <0.5 mm slip, 0.5 N/mm2 tensile adhesion strength after all aging procedures. Even the optional requirement for prolonged open time is achieved (0.5 N/mm2 after 30 minutes).Analogous to the development of a C1T formulation, a further formulation for C2TE is shown in Table 10, Formulation 41, where 1.0 N/mm2 tensile adhesion strength after aging procedures as well as 0.5 N/mm2 after 30 min. open time have to be met.With the exception of the tensile adhesion after the water immersion, the requirements can be met with the addition of only 3% DLP 2000. Formulation 42 meets the C2TE classification with a higher modified cellulose ether XCS 41405.00.This is possible at an elevated water level of 30% with only 2% of redispersible polymer powder. Cellulose ether XCS 41406.00 is used in formulation 43 which meets the C2TE classification at a water level of 32%.
Development of formulations for the EN 12004 classification
Components
Formulation 40 Formulation 41 Formulation 42 Formulation 43
CEM 52.5
Wt.-%
CEM 52.5 Milke
Wt.-%
40
40
Steidle sand
Wt.-%
60
60
Cellulose ether XCS 41142.00
Wt.-%
0.4
Cellulose ether XCS 41403.00
Wt. -%
Cellulose ether XCS 41405.00
Wt. -%
Cellulose ether XCS 41406.00
Wt. -%
Degree of modification
40
60
60
0.5 0.5 0.5 Medium
Medium
Medium-high
High
1
3
2
3
Wt.-%
27
27
30
32
kg/m3
1510
1544
1580
1650
BF 0.5 rpm
mPa·s
2,905,000
4,318,000
3,206,000
2,985,000
BF 5 rpm
mPa·s
445,000
875,000
544,500
352,000
BF 50 rpm
mPa·s
82,000
141,000
79,000
49,000
Slip
mm
0.5
0.5
0.5
0.5
DLP 2000
19
40
Water Properties
Density Rheology
Tensile adhesion strength
Standard
N/mm2
0.92
1.26
1.16
1.37
20 min open time
2
N/mm
1.44
1.17
0.98
1.64
30 min open time
N/mm2
0.85
0.53
0.99
1.56
Heat aging
N/mm2
0.52
1.17
1.13
1.04
Water immersion
N/mm2
1.09
0.93
1.00
1.08
C1T
C1TE+
C2TE
C2TE
meeting EN 12004 classifications Table 10: Formulations of three experimental designs
Experimental
Raw materials
Cement
Identification
Classification
Manufacturer
Normo 4
CEM I 42.5
HCB Siggental, Switzerland
Normo 5
CEM I 52.5
HCB Siggental, Switzerland
Milke cement
CEM I 52.5 R
Milke Geske, Germany
Sand
20
Zimmerli Sand
Steidle Sand
Specific surface: <0.1 m2/g
Specific surface: 2.885 m2/g
Volume
Volume
%
Particle size [µm]
%
Particle size [µm]
10
130
15
80
40
180
10
110
40
230
10
140
10
280
15
80
20
230
20
280
10
360
Cellulose ethers (typical product properties)
Identification
Viscosity [Brookfield RVT, 20 rpm, 2% soln. ] Degree of modification
METHOCEL 10-0356, cellulose ether
10,000 mPa·s
High
METHOCEL 10-0350, cellulose ether
10,000 mPa·s
Medium-high
METHOCEL 10-0366, cellulose ether
10,000 mPa·s
Low
Exp. cellulose ether XCS 41120.00
7,000 mPa·s
Low
Exp. cellulose ether XCS 41142.00
4,000 mPa·s
Medium
Exp. cellulose ether XCS 41403.00
4,000 mPa·s
Medium
Exp. cellulose ether XCS 41405.00
4,000 mPa·s
Medium-high
Exp. cellulose ether XCS 41406.00
4,000 mPa·s
High
Redispersible polymer powder (typical product properties)
Bulk density [g/dm 3]
Ash content [%]
MFT [°C]
Tg [°C]
PVAc/E
425
10
0
6
DLP 2000
PVAc/E
450
10
2
17
DLP 110
PVAc/VeoVa
450
10
4
22
Identification
Polymer
DLP 210
Experimental
Sheet silicate Identification
Mineralogical description
Manufacturer
Pangel S-9
Sepiolite
Grupo Tolsa, Madrid
Bentone GS
Hectorite
Rheox Europe S.A., Bruxelles
Optibent CP
Bentonite
Süd-Chemie AG, Munich
Minugel 200
Attapulgite
ITC, Inc., Maryland, USA
Cellulose fibre
21
Identification
Manufacturer
Arbocell BWW 40
J. Rettenmaier & Söhne
Fibre length [(m]
Fibre diameter [µm]
200
20
Concrete slabs
Identification
Manufacturer/Supplier
Dimensions [m]
Water absorption
l x w x t
EN1323
Concrete flagstones
Antoniazzi, Italy
0.4 x 0.4 x 0.04
0.05 – 0.20 ml
Concrete flagstones
Baubedarf, Horgen
0.5 x 0.25 x 0.04
2.00 – 3.50 ml
Identification
Manufacturer/Supplier
Dimensions [mm]
Standard
Ostara
Laufen Ostara
50 x 50 x 5 cut
EN 159
Uni blanc
Winckelmans
50 x 50 x 5
EN 176
Villeroy Boch
47 x 47 x 3
EN 176
Tiles
Test methods
Consistency measurement
A Brookfield Viscometer equipped with a Helipath spindle was used to determine the consistency (viscosity) of the liquid tile adhesive mortar. The consistency was measured at three shear rates (0.5, 5.0 and 50 rpm). In addition to rotating, the spindle oscillated up and down, to avoid shear aging of the liquid mortar. Testing of all adhesive formulations were carried out according to the Euro-Norm: Slip EN 1308
fully vitrified tiles (EN 176) 100x100 mm; 200g loaded with 50 N for 30 seconds slip determined after 20 minutes
Open time EN 1346
porous tiles (EN159) 50x50 mm loaded with 20 N for 30 seconds; insertion time after 10, 20, and 30 minutes tensile adhesion test after 28 days; the insertion time at which the tensile adhesion still exceeds 0.5 N/mm2 is determined
22
Tensile adhesion EN 1348
Water immersion EN 1348
fully vitrified tiles (EN 176) 50x50 mm loaded with 20 N for 30 seconds; insertion time within 5 minutes after mortar application determination of the tensile adhesion strength after 28 days fully vitrified tiles (EN 176) 50 x 50 mm loaded with 20 N for 30 seconds; insertion time within 5 minutes after mortar application determination of the tensile adhesion strength after 7 days standard climate and 20 days water immersion
Heat aging EN 1348
fully vitrified tiles (EN 176) 50 x 50 mm loaded with 20 N for 30 seconds; insertion time within 5 minutes after mortar application determination of the tensile adhesion strength after 14 days standard climate and 14 days at 70°C
Transverse determination of the transverse defordeformation mation of tile adhesives and grouts: The maximum deflection and the maxi EN 12002 mum stress of a (280 x 45 x 3mm) mortar strip is determined after curing for 14 days in a polyethylene bag and 14 days at standard climate conditions
For more information about METHOCEL cellulose ethers and DLP redispersible polymer powders contact DOW at: Telephone: international +800 3694 63 67, Fax: international +32 34 50 28 15 Website: www.methocel.com, email:
[email protected]
No freedom from any patent owned by Seller or others is to be inferred. Because use conditions and applicable laws may differ from one location to another and may change with time, Customer is responsible for determining whether products and the information in this document are appropriate for Customer’s use and for ensuring that Customer’s workplace and disposal practices are in compliance with applicable laws and other governmental enactments. Seller assumes no obligation or liability for the information in this document. NO WARRANTIES ARE GIVEN; ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY EXCLUDED. Notice:
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