The Explanation of Chinese cementitious tile adhesive standard (JC/T 547-2017)
Warm-up
In this article, I translate the Chinese industrial standard of ceramic tile adhesive.
There are three main types of tile adhesives in the construction material market, cementitious adhesive, dispersion adhesive, and reaction resin adhesive.
The cementitious adhesive(C) is the composition of water-hardened inorganic cementitious material(cement), aggregate (sand), and additives. it is a uniformly mixed powder ready to use with water on site.
The dispersion adhesive(D) is the composition of water-based latex, additives, and mineral stuff, it can be mixed for direct use.
The reaction resin adhesive(R) consists of synthetic resin, mineral stuff and additives, etc, it can be a single part or multiple parts, they are solidified via chemical reaction when used.
In this article, we mainly introduce cementitious adhesive and explain the industrial standard in PRC for ceramic tile adhesive.
1. Ceramic tile adhesives are divided into different categories due to their properties
These categories are indicated through numbers, alphabet listed below:
2. Different types of products come from different combinations of properties
The product code consists of three parts, the first alphabet represents the product's type; the second number represents the product's property; the third alphabet represents special property( Blank indicates no special property).
3. The technical requirement for cementitious adhesive
The cementitious adhesive should comply with the basic requirement of the C1 column in Table 3 below, the water volume added should be the same. Special property requirements are shown in Table 4 below.
4. Testing method
4.1 Testing sample
The cementitious samples for the test must be taken more than 2 kg.
4.2 Testing conditions
The standard condition is
Temperature: 23±2 ℃；
Relative humidity: 50 ± 5 %;
The cycling wind speed should be lower than 0.2 m/s
The time length starts from the point when cementitious adhesive mixes with water to the time point conducting the test of tensile bond strength.
The maintenance time tolerances are shown below:
4.3 Testing material treatment in advance
4.3.1 Before testing, all the test materials ( water is also contained) should be settled in standard conditions for 24 hours at least. the samples should be in their shelf life.
4.3.2 The ceramic tile for the test should be dry, clean, and not used.
4.4 Mixture steps
The water volume used should comply with the recommendation of the manufacturer, in other words, the ratio between water and powder should be defined. if the recommendation is in scope, the middle value should be used.
Putting the adhesive and water needed into the mixer which conforms to JC/T 681 requirement, and stirring them at low speed.
The procedure is listed below:
a), Putting the water into a stir pot；
b), Putting the adhesive powder into the water;
c), String 30 seconds;
d), lift the impeller up;
e), Sctrach the adhesive on the wall of the pot and the impeller within 1 minute.
f), Put down the impeller and re-stir it for 1 minute.
4.5 Testing substrate
The concrete board for testing should adopt 400mm X 400mm X 40mm or 400mm X 200mm X 40mm specifications, if conflicts occur, it should adopt the former one.
The moisture content of the concrete board should be less than 3% (weight), and the volume of water absorbing in 4 hours should be in the range of 0.5 cm3 and 1.5cm3.
The concrete board for testing should be settled in standard condition for 3 months. it also can be settled for 5 hours at 105 ℃ and for 24 hours in standard condition afterward instead. When it comes to some arguments, the result should adopt the former one.
4.6 Damage mode
4.6.1 Cementitious adhesive damage (AF-S or AF-T)
The damage occurs on the surface between the adhesive and substrate (AF-S) or on the surface between the adhesive and ceramic tile (AF-T), the testing value is the bonding strength. In some cases, the damage takes place at the bonding layer between the tile and the pulling head(BF), the bonding strength should surpass the testing value, the result is invalid, and then re-testing.
①，Pulling head;
②, Ceramic tile;
③, Adhesive;
④, Substrate (concrete board)
4.6.2 Adhesive cohesive failure
The damage occurs in the adhesive layer.
4.6.3 Substrate or ceramic tile cohesive failure (CF-S or CF-T)
The damage occurs in the substrate interior or tile interior, in that case, the bonding strength is higher than the testing result. then it should re-test.
4.7 Testing report
The testing result should include the information below:
a), Open Time;
b), Slip;
c), Tensile bonding strength;
d), Transverse deformation;
4.8 Opening time testing
4.8.1 General principles
Open-time testing should be done under the standard condition and according to the procedure defined below.
4.8.2 Testing material
4.8.2.1 Ceramic tile: Dry-press ceramic tile in line with BIII, L, attachment of GB/T 4100-2015. The dimension is cut into (50±1)mm X (50±1)mm, the thickness is 7mm ~ 10mm, the depth of the texture in the background is not less than 0.25mm.
4.8.2.2 Testing substrate: according to the requirement of 4.5
4.8.3 Testing equipments:
4.8.3.1 Pressing block: section dimension: 50mm X 50mm, can impose (2000±15)g pressure evenly.
4.8.3.2 Pull head: Metal block with 50±1mm side length square and not less than 10mm thickness; Can be connected with testing machine.
4.8.3.3 Testing machine: Suitable measuring range, 1% accuracy, loading speed: 250±50 N/s.
4.8.4 Testing procedure
The adhesive should be mixed according to the requirement of 4.4.1, Paint a thin layer of adhesive with straight edge trowel on the concrete board with some pressure, then, Paint a thick layer of adhesive with a notach trowel, and then comb the adhesive with 6mmX6mm notch trowel; the angle of the trowel and the concrete board is 60° approximately. the trowel should be vertical to one side of the concrete board, smearing to the end edge parallelly ( moving straightly).
At least 10 testing ceramic tiles are placed with a 40mm gap on the adhesive before the deadline. Each square tile should cover 4 combing bars on the adhesive. and put the 2000±15g pressing block on it and keep it for 30 seconds.
The testing specimen should be held at standard conditions for 27d, afterwards, bonding the tile with metal pull head with high strength adhesive.
Keep them under the standard condition for another 24h, and then take them out and fix them on the testing machine, meaure the tensile bonding strength with the speed 250±50N/s.
4.8.5 The assesment and indication of the testing result
Tensile bonding strength should be calculated with the fomula below, the result is accurate to 0.1MPa.
As-------Tensile bonding strength, Unit(MPa);
L -------- Tensile load, unit(N);
A --------Bonding area, 2,500m㎡
The tensile bonding strength should be calculated according to the principle below:
a), Calcuate Arithmetic mean of 10 results;
b), Remove the results which are out of 20% range of average;
c), If the remianing data is more than 5, average value should be re-calculated;
d), if less than 5, the testing experiment should be re-conducted.
e), The damaged mode should be reported.
The unit of opening time is Minete.
4.9 Slip testing
4.9.1 General principle
Slip testing should be done under the standard conditions and according to the steps below.
4.9.2 Testing materials
4.9.2.1 Ceramic tile: Dry-press ceramic tile in line with BIII, L, attachment of GB/T 4100-2015. unglazed， The dimension is 100±1mm X 100±1mm, the weight is 200±10g, the thickness is 8mm ~ 10mm.
4.9.2.2 Testing substrate: according to the requirement in 4.5.1
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4.9.3 Testing equipemt
4.9.3.1 Steel straight ruler
4.9.3.2 Fixture
4.9.3.3 Shelter adhesive tape: 25mm wide
4.9.3.4 Gap sheet: （25±0.5）mm X （25±0.5）mm X （10±0.5）mm, stainless steel, 2 sheets.
4.9.3.5 Pressing block: section area (100±11)mm X (100±1)mm, weight: (5.00±0.015)kg.
4.9.3.6 Vernier caliper with accuracy of 0.01mm.
4.9.4 Testing procedure
Fix the steel straight ruler on the concrete board and be parallel to the top edge of the concrete board, so the ruler keep the same horizon with the board edge when the concrete board stand up verticlally.
Paste a strip of 25mm-wide shelter adhesive tape at the bottom edge of the steel ruler. Smear a thin tile adhesive with a straight edge trowel on the concrete board.
Next, Paint a thick layer of tile adhesive on it and cover the shelter tape's bottom justly, and then comb the adhesive with a 6mm X 6mm notch trowel.
Holding the trowel at a 60° angle to the board, and pulling it to the edge of the concrete board parallelly.
Next, get rid of the shelter adhesive tape immediately, and put the stainless steel gap sheets in the position of the tape. 2 minutes later, put the testing tile(4.9.1.1) next to the gap sheets, and press it with a pressing block, keeping it for (30±5) s.
Take the span sheets out, and measure the distance between the ruler's bottom and the ceramic tile which should be accurate to ±0.1mm. and then put the concrete board vertically carefully, after (20±2）min, measure the distance again.
The difference between the two results is the distance of the slip with self-gravity. （unit: mm）
4.10 Adhesion strength testing
4.10.1 General principle
Adhesion strength testing should be done under the standard condition according to 4.2 and the steps below.
4.10.2 Testing materials
4.10.2.1 Ceramic tile: extrusion ceramic tile according to the requirement AIa GB/T 4100-2015. The dimension is (50±1)mm X (50±1)mm, the thickness is (5±2)mm.
4.10.2.2 Testing substrate: according to the requirement of 4.5
4.10.3 Testing equipment
4.10.3.1 Pressing block, the section area: 50mm X 50mm, weight (2.00±0.015)kg.
4.10.3.2 Pulling head, dimension (50±1)mm X(50±1)mm, Square metal block with 10mm thickness at least which can be connected with the testing machine.
4.10.3.3 Testing machine: appropriate measuring range, be accurate to 1%. the loading speed is 250±50N/s.
4.10.3.4 Blast drying oven. temperature accuracy ±3℃.
4.10.4 Testing precedure
4.10.4.1 Specimen preparation according to the requirement of 4.8.4
4.10.4.2 Tensile adhesion strength
The specimen should be maintained for 27d under the condition of 4.2, bond the pull head with the testing tile with high-strength adhesive(epoxy), and then be placed in the same way for 24h, check the adhesion strength at （250±50）N/s loading speed. if testing fast-cure adhesive, the pulling head should be bonded 2 hours before.
The result should be indicated with unit N (Newton).
4.10.4.3 Adhesion strength after soaking in water
After being maintained for 7d under the condition of 4.2, the specimen should be soaked in water for 20d, and then, get it out, wipe the water on its surface bond the pull head, and keep it in standard condition for 7 hours, and then continue to keep them underwater in standard condition for 17 hours. finally, get it out of the water and check it on the testing machine. the loading speed is （250±50）N/s.
The result should be indicated with unit N (Newton).
4.10.4.4 Adhesion strength after heating age
4.10.4.5 Adhesion strength after freeze-thaw cycle
The specimen is prepared according to 4.8.4. The testing tile block should be painted with a 1mm thick tile adhesive with a straight-edge trowel before bonding onto the substrate. and then, the specimen should be maintained for 7 days under standard conditions and 21 days underwater. after getting them out of the water, 25 freeze-thaw cycles should be conducted.
Each freeze-thaw cycle includes:
a), Get the specimen out of water, and decrease the temperature to -15±3℃ ;
b), The specimen is kept at -15±3℃ for 2h±20min;
c), Put the specimen into water at 20±3℃, and increase the temperature to 15±3℃, keep this status for 2 hours at least before the next cycle.
d), Repeat this cycle 15 times.
After 25 freeze-thaw cycles, put the specimen in the standard conditions, bond the pull head, and check the adhesion strength within 24 hours.
The result should be indicated with unit N (Newton).
4.11 Transverse deformation testing
4.11.1 General principle
The transverse deformation test should be conducted under the standard conditions of 4.2 and the steps below.
4.11.2 Testing materials and equipment
4.11.2.1 Isolating film: polyethylene film with 0.15mm thick at least.
4.11.2.2 Plastic container can be sealed and airtight, the inner volume is (26±5)L, for example, the dimension is (600±20)mm X (400±10)mm X (110±10)mm.
4.11.2.3 Support： rigid, smooth, and flat equipment to support the PE film.
4.11.2.4 Testing press head according to the diagram below:
4.11.2.5 Testing support, two metal cylinder supports with a diameter of (10±0.1)mm, the length is 60mm at least. the central distance is (200±1)mm.
1----cylinder supports; diameter (10±0.1)mm, the length is 60mm at least;
2----The thickness of tile adhesive is (3±0.1)mm;
a: cross-section.
4.12.2.6 Model A, the inner dimension is (280±1)mm X (45±1)mm, the thickness is (5±0.1)mm, smooth, rigid, not absorbing water, rectangle frame. it can be made from PTFE of metal. each corner is recommended with a 2mm-diameter hole in order to facilitate specimen preparation.
4.12.2.7 Model B, Smooth, rigid, and not absorbing water to produce the specimen with the dimension of (300±1)mm X (45±1)mm X (3±0.05)mm.
4.12.2.8 Testing machine, with a suitable measuring range, can impose pressure at 2mm/min loading speed.
4.12.2.9 The vibration table, according to the requirement of JC/T 958-2005, is used to vibrate the specimen tightly.
4.12.3 Testing procedure
4.12.3.1 Substrate preparation
Place PE film on the rigid support and fix them. Make sure the surface is not able to be deformed and twisted, for instance, without any folds.
4.12.3.2 Specimen preparation
Press model A on the PE film tightly, paint sufficient tile adhesive in the model scratch them flatly, make the adhesive smooth, and stuff the hole in the corner.
Fix model A on the vibrate table tightly, vibrate them 70 times, and then, pick up mode A carefully from the vibrate table.
Paint release agent on Model B, place it in the center of the specimen, and impose a pressing block with a cross-section of (290X45)mm, weight (10±0.1)kg, the pressure imposed can ensure the model completely be stuffed with the required thickness. and then, scratch off the adhesive overflow. after one hour, remove the pressing block, and 48 hours later, remove Model B.
Preparing 6 specimens once.
4.12.3.3 Maintenance
After removing Model B, place the 6 specimens on the support, and then put them into a plastic container horizontally and keep them airtight.
Maintain them in the plastic container for 12 days at (23±2)℃, and take them out, continue to keep them in standard condition for 14 days.
4.12.3.4 Testing
After maintenance, remove the PE film and measure the thickness with a caliper(0.01mm accuracy) at three positions. for example, the middle point and the two points with (50±1)mm distance from the center on two sides. If the testing values are within the tolerance of (3.0±0.1)mm, then, calculate the average. Remove the specimen that is out of the tolerance range.
Put the specimen on the testing fixture;
When the testing head just touches the specimen, the point is defined as a start point, from this point, impose a 2mm/min load and make it deform until it is destroyed.
Record the deformation value, the result is indicated with mm.
Repeat the steps above, and test 3 specimens at least.
4.12.4 Result assessment and indication
Take the average of the results, the results should be accurate to 0.1mm.
5 The checking results
The checking item of cementitious adhesive for tile
(end)