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194

NOTES TO THE SPECIFICATION TABLE

Water absorption

– is the ratio of the mass of water absorbed by the sample at its

full saturation to the dry mass of the sample. Water absorption rate of porcelain gres

shall be defined according to EN ISO 10545-3. Water absorption rate shall not ex-

ceed 0.5%. According to the European standard

EN14411

, dry-press ceramic tiles

are divided into the following groups according to the water absorption rate:

BIa group

– low water absorption rate E

0.5%

BIb group

– low water absorption rate 0.5<E

3%

BIIa group

– water absorption rate 3% < E

6%

BIIb group

– water absorption rate 6%<E

10%

BIII group

– water absorption rate E>10%

Glaze cracking resistance

– a feature indicating if the tile glaze can stand high

temperature (159±1

O

С) and pressure (500±20 kPa) without cracking.

Strength properties

According to EN ISO 10545-4 strength properties include breaking load, breaking

stength and modulus of rupture measured at a definite force speed applied in the

middle of the tile.

Breaking load

– a value of force, in Newton, the application of which causes

the damage of the tested sample. It is measured according to a measuring

instrument scale.

Breaking strength

– a value, in Newton, generated by the multiplication of the

breaking load and the distance between support bars divided by the width

of the tested sample.

Modulus of rupture

– a value, in Newton/mm, generated by the division of the

estimated breaking strength by the squared minimum thickness of the tested

sample along the fracture line.

Deep abrasion resistance

– one of the major characteristics of porcelain gres, the

standard value of which is set by the international standard EN ISO10545-6. It ba-

sically indicates the number of cubic millimeters the tested material loses under

certain abrasive impact. It largely depends on the type of the tile final treatment:

grinding, polishing, saturation with a synthetic mixture etc. Water absorption rate

is also important for this parameter: the higher is water absorption rate, the lower

is deep abrasion resistance rate.

Wear resistance of the surface (degree of wear resistance PEI)

is one of the major

properties of glazed tiles for flooring which influences on how long the tile

surface will preserve its exterior appearance without visible changes. Ac-

cording to the European standard

EN14411

(Appendix N), glazed ceramic

tiles are classified into 6 groups depending on their wear resistance:

Class 0

Glazed ceramic tiles of this class are not recommended for floors.

Class 1

is recommended for floors subject to no abrasive dirt, or areas where shoes with

soft soles or no shoes are used (e.g. bathrooms in apartments and bedrooms

without an entrance from the outside).

Class 2

is recommended for floors subject to a minimum level of abrasive dirt and

areas where shoes with soft sole or ordinary shoes are used (living premises

in the houses, except for kitchen, entrance hall and similar premises involving

much walking. This shall not include special shoes, e.g. high-heeled shoes).

Class 3

is recommended for floors subject to a low level of abrasive dirt, areas where

ordinary shoes are used and premises involving much walking (e.g. kitchen, en-

trance hall, corridors, balcony, loggia and terrace. This shall not include special

shoes, e.g. high-heeled shoes).

Class 4

is recommended for floors subject to a low level of abrasive dirt and premises

subject to regular walking at the rate higher than for class 3 (e.g. kitchen at the

production enterprise, hotels, showrooms and commercial premises).

Class 5

is recommended for floors subject to a low level of abrasive dirt and premises

subject to intense walking for a long period of time which puts an excessive load

on the glazed ceramic tile (e.g. public premises, such as shopping malls, airport

lounges, hotel lobbies, public pedestrian paths and industrial zones).

Calibre

(

nominal size)

– is a conventional designation of manufacturing size of the

tile set for the production process, the actual size of the tile shall correspond to,

with account of certain tolerance limits. The product is sorted into lots of one pro-

duction size (calibre). Size is marked on a package.

Shade

– colour value of a ceramic tile or porcelain gres lot that can slightly differ

from the declared colour. The shade is marked on a container with a number.

Thermal expansion coefficient

indicates the increase/decrease of the tile dimen-

sions during heating/cooling. It is extremely important for laying of porcelain gres

over big areas indoors (to calculate the width of the expansive joints properly)

and outdoors (in order to select the best suitable fastening option, type of adhe-

sive compound and calculate tile-to-tile gaps).

Thermal shock resistance

– the ability of ceramic items to endure sharp temper-

ature changes. This parameter depends on various physical, chemical and ther-

momechanical properties of the material, its shape, size, heating and cooling

conditions.

Frost resistance

– ability of water saturated ceramic items to resist without any

damage the impact of multiple freezing in the air and thawing in water.

Frost resistance degree is a number of cycles (freeze/thaw) a sample

stands without any damage. According to EN ISO 10545-12 control pro-

cedures the freeze/thaw cycle is repeated not less than 100 times.

Stains resistance

is defined in compliance with ISO 10545-14. There are three

main polluting agents: special ink, iodine alcoholic solution, and olive oil.

The resistance rate of a ceramic surface to polluting agents depends on the effi-

ciency and ease of their removal. There are four cleaning procedures applied in

combination with the corresponding cleaning agents (hot water, weak cleaning

agent, strong cleaning agent, and various solvents).

Procedure А

– running hot water.

Procedure В

– manual cleaning with a weak cleaning agent.

Procedure С

– mechanical treatment with a strong cleaning agent.

Procedure D

– dipping into the corresponding solvent.

The class is assigned upon completion of a visual assessment of the result. The

highest class of stains resistance and stains removal ease is class 5; the lowest

one is class 1. Minimum admissible class for porcelain gres is class 3.

Chemical stability

— ability of the tile (glaze) surface or porcelain gres to withstand

a contact with chemical substances (household chemistry products, additives for

pools, salts and acids) at room temperature without getting its appearance

changed. Acc. to

ISO 10545-13

ceramic tile and porcelain gres are classified into

Chemical Stability groups as follows:

Unglazed (UGL)

Class A

– no visual changes;

Class B

– visual changes at the shear surface

Class C

– visual changes at the shear surface, on the sample edge and on

the front side.

Glazed (GL)

Class A

– no visual changes;

Class B

– strong changes of the appearance;

Class C

– partial or full loss of the original surface.

Before the letter of Class, a letter standing for the tile type (G-glazed, U-unglazed)

is added. Letter H in the abbreviation indicates resistance to acids and alkali of

high concentration; letter L indicates respectively low concentration. If none of

these letters is added, it means that the tile is resistant to household chemical

agents and additives for swimming pools. Thus, UHA, ULA or UA abbreviations

stand for "unglazed tile belonging to A Class". GHB, GLB or GB abbreviations

stand for "glazed tile, belonging to B Class".

Frictional coefficient

KERAMA MARAZZI porcelain gres has been tested with the help of the BCR (Вri-

tish Ceramic Research Association) method developed in Great Britain to define

coefficient of sliding friction. This method is applied to test porcelain gres at all

enterprises within the MARAZZI GROUP. BCR method utilizes a classifying scale

from 0 to 1. According to the scale 0.1 friction coefficient means «hazardous»,

while 0.9 friction coefficient means «excellent».

BCR friction coefficient of KERAMA MARAZZI porcelain gres is equal to >0.4,

which is considered a satisfactory degree of friction resistance according to the

classifying scale.

In compliance with BCR method, KERAMA MARAZZI porcelain gres is a product

with skid-proof surface suitable for all types of premises with no tough require-

ments set to skid-proof properties.

! Defining the friction coefficient is not mandatory for the manufacturers undergoing

the certification procedures, since none of the methods is included into the Euro-

pean standards.

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