AVOIDING TILE FAILURESFrancesco Stronati

Director of Technical Services

Tuesday 19th October 2010

Malone House, Barnett Desmene Belfast

PREPARATION OF SUBSTRATES

SUITABLE FOR THE LAYING OF CERAMIC

TILES

ASSESMENT AND PREPARATION OF

SUBSTRATES:

• Cementitious screeds and screeds based on special binders

• Smoothing compounds

• Old ceramic or natural stone floorings

• Concrete

•Wood, Chipboard, PVC, linoleum or rubber floorings, metallic surfaces

• Render

• Gypsum or Anhydrite

• Lightweight cement blocks

• Old painted surfaces

TECHNICAL AND PERFORMANCE

CHARACTERISTICS OF THE SCREED

To be suitable for the laying of ceramic tiles or natural stone, a screed must have the following characteristics:

•Sufficient thickness

•Sufficient mechanical strength

•Solid

•Cured and dimensionally stable

•Dry

•Clean

•Free of cracks

•Smooth and level

UNBONDED SCREED

POLYTHENEPOLYTHENE

SCREEDSCREED

FLEXIBLE FLEXIBLE

MATERIALMATERIAL

UNBONDED SCREED

1. MINIMUM THICKNESS ≥≥≥≥ 5.0 cm

2. POLYTHENE

3. FLEXIBLE MATERIAL

4. FLOOR

5. BS 8204-1

FLOATING SCREED

1. MINIMUM THICKNESS ≥≥≥≥ 7.5 cm

(domestic / light loading ≥≥≥≥ 6.5 cm)

WITH ELECTROWELDED MESH

2. POLYTHENE

3. FLEXIBLE MATERIAL

4. INSULATING LAYER

5. FLOOR

BONDED SCREED

Casting of the screed over fresh slurry bond coat based of:

• Epoxy resin

• Synthetic-rubber latex additive mixed with water and with the material (binder) used to make the screed

HEATED SCREED

HEATED SCREED

1. SCREED THICKNESS (THICKNESS

OVER PIPES ≥≥≥≥3.5 cm)

2. ELECTROWELDED MESH

3. HEATING PIPES

4. FLEXIBLE MATERIAL

5. THERMAL INSULATION LAYER

6. FLOOR

WAITING TIME BEFORE CARRYING OUT HEATING CYCLE

Cement +

aggregate +

water +

MAPEFLUID N200

Cement +

aggregate +

water +

MAPEFLUID PZ 500

TOPCEM

PRONTO +

water

TOPCEM +

aggregate +

water

MAPECEM

PRONTO +

water

MAPECEM +

aggregate +

water

21 days 14 days 4 days 4 days 1 day 1 day

PRESENCE OF PIPES

Over the pipes there must always be a minimum

thickness of the screed of approx. 3.5 cm. To

reinforce this small section of the screed and to

limit the formation of cracks it is necessary to

position a wire mesh over the pipes.

It is essential that the heating system is

commissioned before any floor tiling is

commenced.

TECHNICAL AND PERFORMANCE

CHARACTERISTICS OF THE SCREED

To be suitable for the laying of ceramic tiles or natural stone, a screed must have the following characteristics:

•Sufficient thickness

•Sufficient mechanical strength

•Solid

•Cured and dimensionally stable

•Dry

•Clean

•Free of cracks

•Smooth and level

MECHANICAL STRENGTH

The mechanical strength of a screed must be

suitable for the foreseen service conditions and

for the type of floor covering to be laid:

• BS 5385, part 3, Annex C

SCREED COMPOSITION

• Water, cement and aggregates

• Water, cement, aggregates + superplasticizing admixtures (such as MAPEFLUID N200 or MAPEFLUID PZ 500)

• Normal setting, fast drying – 4 days - special binder (such as TOPCEM) to be mixed with water and aggregates

• Fast drying - 24 hours – special binder (such as MAPECEM) to be mixed with water and aggregates

• Fast (such as TOPCEM PRONTO) or quick (such as MAPECEM PRONTO) drying, ready-to-use, pre-blended mortar to be mixed only with water.

TOPCEM TOPCEM

PRONTO

MAPECEM MAPECEM

PRONTO

RESIDUAL MOISTURE (%)

after 24 hours

after 3 days

after 4 days

<4

<3

<2

<4

<3

<2

<2

<1,6

-

<2

<1,6

-

SMOOTHING COMPOUND 1÷÷÷÷ 4 days 1 ÷÷÷÷ 4 days 4 hours 4 hours

TIME BEFORE LAYING

ceramic

natural stone

wood

24 hours

2 days

4 days

24 hours

2 days

4 days

3 ÷÷÷÷4 hours

3 ÷÷÷÷4 hours

1 day

3 ÷÷÷÷4 hours

3 ÷÷÷÷4 hours

1 day

COMPR. / FLEX. Strength

(N/mm2)

after 24 hours

after 3 days

after 4 days

after 7 days

after 28 days

>7/4

-

>20/5

>25/6

>30/7

>7/4

-

>20/5

>25/6

>30/7

>30/5

>40/6,5

-

-

>45/7

>40/6

>50/7

-

-

>62/10

TECHNICAL AND PERFORMANCE

CHARACTERISTICS OF THE SCREED

To be suitable for the laying of ceramic tiles or natural stone, a screed must have the following characteristics:

•Sufficient thickness

•Sufficient mechanical strength

•Solid

•Cured and dimensionally stable

•Dry

•Clean

•Free of cracks

•Smooth and level

COMPACTNESS

The screed must be solid and well-blended throughout its entire thickness. If there are layers or areas with lower compactness it is possible to consolidate the screed by means of impregnation using:

• two-component epoxy-based primer (such as PRIMER EP(20%) or PRIMER MF(100%) in case plus PRIMER KL)

• one-component polyurethane-based primer (such as ECOPRIM PU 1K(100%))

• silicate mixture in water (such as PROSFAS(24%))

PRIMER EPPRIMER EP

PRIMER MFPRIMER MF

TECHNICAL AND PERFORMANCE

CHARACTERISTICS OF THE SCREED

To be suitable for the laying of ceramic tiles or natural stone, a screed must have the following characteristics:

•Sufficient thickness

•Sufficient mechanical strength

•Solid

•Cured and dimensionally stable

•Dry

•Clean

•Free of cracks

•Smooth and level

CONTROL JOINTS

The incorporation of check joints in the screed

make sure that the formation of cracks due to

hygrometric shrinkage occur in pre-established

sections of the screed.

Cuts are made in the screed to a depth of at least

1/3 of its thickness. The screed is, therefore,

locally weakened which favours the formation of

cracks exactly at those points.

Correct size for check

joints

Formation of shrinkage cracks

in the wrong position due to

shallow cuts in the presence of

an irregular substrate

WHEN ARE CONTROL JOINTS

REQUIRED?

In floating / unbonded screeds, they must be made every 20-

25 m² for internal applications, and at least every 16 m² for

external applications.

In the case of screeds made with controlled shrinkage

binders, such as TOPCEM or MAPECEM, TOPCEM PRONTO

or MAPECEM PRONTO the bay size may be increased

accordingly.

In bonded screeds, the joints must be made in

correspondence with the joints in the substrate.

The expansion joint in the tiles does not correspond with the control joint in the screed.

TECHNICAL AND PERFORMANCE

CHARACTERISTICS OF THE SCREED

To be suitable for the laying of ceramic tiles or natural stone, a screed must have the following characteristics:

•Sufficient thickness

•Sufficient mechanical strength

•Solid

•Cured and dimensionally stable

•Dry

•Clean

•Free of cracks

•Smooth and level

HIGH RESIDUAL MOISTURE

Too high amount of mixing

water

Aggregate too rich in fine

parts and dirty

No vapour barrier

Accidental contact with water

on the finished screed

Excessive wetting during

finishing and excessive

floating / trowelling

DRYING

EFFLORESCENCE OF

CALCIUM CARBONATE

CAUSED BY MOISTURE

COMING FROM

SUBSTRATE

It is necessary to ensure that, in case of absence

of a vapour barrier, also the layers below the

screed are dry.

In case of rising damp, a functioning and long

lasting vapour barrier must be guaranteed.

DRYING

TECHNICAL AND PERFORMANCE

CHARACTERISTICS OF THE SCREED

To be suitable for the laying of ceramic tiles or natural stone, a screed must have the following characteristics:

•Sufficient thickness

•Sufficient mechanical strength

•Solid

•Cured and dimensionally stable

•Dry

•Clean

•Free of cracks

•Smooth and level

CLEANING

The surface of the screed must be perfectly

clean.

Dust, laitance, dirt and debris must be removed

because they can compromise the adhesion of

the smoothing compound or of the adhesives.

6 c

m

1.5

cm

CLEANING

Remove dust and proceed with the application of a suitable

FIXING PRIMER based on synthetic resins dispersed in water, with also the aim to provide uniform substrate absorption

before levelling(such as PRIMER G or ECOPRIM T)

Where laitance is present, remove this layer mechanically and then proceed with the application of a suitable

CONSOLIDATING PRIMER CONSOLIDATING PRIMER based on epoxy resinsbased on epoxy resins, , to to consolidate the superficial part of the screedconsolidate the superficial part of the screed

(such as(such as PRIMER MF)PRIMER MF)

TECHNICAL AND PERFORMANCE

CHARACTERISTICS OF THE SCREED

To be suitable for the laying of ceramic tiles or natural stone, a screed must have the following characteristics:

•Sufficient thickness

•Sufficient mechanical strength

•Solid

•Cured and dimensionally stable

•Dry

•Clean

•Free of cracks

•Smooth and level

CRACKS

•Hygrometric shrinkage

• In correspondence with construction joints not well realized

• Above pipes where there was an inadequate thickness of the screed

Too high amount of mixing water

Too fine aggregate

Too high amount of binder

Lack of control joints

Before proceeding to apply a levelling

compound, it is necessary to monolithically

seal the cracks by pouring a solvent free two

component epoxy resin

(such as EPORIP, EPOJET or EPOJET LV)

Seal with EPORIP, EPOJET or EPOJET LV

epoxy resin, or with EPORIP TURBO polyester

resin

CRACKS

TECHNICAL AND PERFORMANCE

CHARACTERISTICS OF THE SCREED

To be suitable for the laying of ceramic tiles or natural stone, a screed must have the following characteristics:

•Sufficient thickness

•Sufficient mechanical strength

•Solid

•Cured and dimensionally stable

•Dry

•Clean

•Free of cracks

•Smooth and level

Requirement of REGULARITYRequirement of REGULARITYRequirement of REGULARITYRequirement of REGULARITY

FLATNESS (Floors and Walls)

Method: ISO 7976-1 clause 7.3.1

BS 5385-3 clause 7.1.4

Reference limit :

Tolerance = ± 3 mm under 2 m rule

Note: Laying with adhesive: flatness of ceramic floor

depends on flatness of substrate

ASSESMENT AND PREPARATION OF

SUBSTRATES:

• Cementitious screeds and screeds based on special binders

• Smoothing compounds

• Old ceramic or natural stone floorings

• Concrete

•Wood, Chipboard, PVC, linoleum or rubber floorings, metallic surfaces

• Render

• Gypsum or anhydrite

• Lightweight cement blocks

• Old painted surfaces

ECO PRIM T – MAPEPRIM SP

In case of laying over old ceramic or natural stone floorings it is very important to proceed with the

following operations:

1.Cleaning of old flooring

2.Abrasion of the surfaces when required

3.Examination of old flooring conditions(adhesion and presence of cracks)

4.Repair of damaged parts with NIVORAPIDNIVORAPID(+ LATEX PLUS)(+ LATEX PLUS) or with ADESILEXADESILEX P4P4

5.Laying of the new flooring respecting existing structural and expansion joints

ASSESMENT AND PREPARATION OF

SUBSTRATES:

• Cementitious screeds and screeds based on special binders

• Smoothing compounds

• Old ceramic or natural stone floorings

• Concrete

•Wood, Chipboard, PVC, linoleum or rubber floorings, metallic surfaces

• plaster

• Gypsum or anhydrite

• Blocks of cellular cement such as Gasbeton

• Old painted surfaces

ASSESMENT AND PREPARATION OF

SUBSTRATES:

• Cementitious screeds and screeds based on special binders

• Smoothing compounds

• Old ceramic or natural stone floorings

• Concrete

•Wood, Chipboard, PVC, linoleum or rubber floorings, metallic surfaces

• Render

• Gypsum or anhydrite

• Lightweight cement blocks

• Old painted surfaces

Timber floors must be firmly fixed using screws not nails or ring shank nails. The surface to be tiled

must be clean and free from wax, grease, oil, paint or other materials that can cause detachment.

Direct fixing to plywood, chipboard and floorboards is possible with the correct preparation, using the correct choice of adhesive and where necessary

anti-fracture membranes.

Levelling of substrates particularly deformable (timber floors, metallic surfaces, rubber, linoleum) can be

carried out by the use of smoothing compounds with high adhesion and elasticity, prepared by mixing ultra fast drying thixotropic cementitious materials (such

NIVORAPID or PLANIPATCH) with plasticizing admixtures (such LATEX PLUS).

The use of plasticizing admixtures reduces the modulus of elasticity of the smoothing compound and

therefore increasing the adhesion to “difficult”substrates.

MAPEI SMOOTHING AND LEVELLING

COMPOUNDS

ASSESMENT AND PREPARATION OF

SUBSTRATES:

• Cementitious screeds and screeds based on special binders

• Smoothing compounds

• Old ceramic or natural stone floorings

• Concrete

•Wood, Chipboard, PVC, linoleum or rubber floorings, metallic surfaces

• Render

• Gypsum or anhydrite

• Blocks of cellular cement such as Gasbeton

• Old painted surfaces

• To verify the performance of a render

or adhesion of coverings to the

substrate it must be determined by a

pull-out test with a dynamometer

• Fixing tiles to external façades must be carried out using improved

adhesives classified as C2 (according to EN 12004).

Consequently a render’s resistance to the pull-out test must be

≥≥≥≥ 1N/mm²

EXTERNAL DETACHMENT DUE TO COHESIVE FAILURE OF THE RENDER

Fixing ceramic or natural stone is possible

only after the curing of the render –

minimum 2 weeks (BS 5385 parts 1 & 2)

(7-10 days/cm of thickness)

It is advisable to insert a metallic mesh in

the render by string-courses and at the

border between concrete and masonry.

CRACKINGS BETWEEN CONCRETE AND MASONRY

crackbeam

masonryGalvanized

mesh

ASSESMENT AND PREPARATION OF

SUBSTRATES:

• Cementitious screeds and screeds based on special binders

• Smoothing compounds

• Old ceramic or natural stone floorings

• Concrete

•Wood, Chipboard, PVC, linoleum or rubber floorings, metallic surfaces

• Plaster

• Gypsum or anhydrite

• Blocks of cellular cement such as Gasbeton

• Old painted surfaces

Plasters based on gypsum must be at least 4 weeks

old. Anhydrite screeds must have residual moisture

less than 0.5% (by weight)

When the laying of tiles has to be carried out using

cementitious adhesives, the gypsum based

substrates must be treated in advance with a primer

(such as PRIMER GPRIMER G) to prevent the chemical

reaction between gypsum sulphates and cement

aluminates which, in damp environments, forms a

salt that can cause the detachment of the covering.

In addition anhydrite screeds must be abraded to

remove any surface laitance.

ASSESMENT AND PREPARATION OF

SUBSTRATES:

• Cementitious screeds and screeds based on special binders

• Smoothing compounds

• Old ceramic or natural stone floorings

• Concrete

•Wood, Chipboard, PVC, linoleum or rubber floorings, metallic surfaces

• Plaster

• Gypsum or anhydrite

• Lightweight cement blocks

• Old painted surfaces

EXTERNAL FIXING: fixing directly on this substrate is

not advisable since it tends to be dusty, mechanically

weak and, therefore, unable to contrast the stresses,

caused by different thermal expansion coefficient,

between substrate and covering materials.

In these cases it is ALWAYS necessary ,before laying

coverings materials, to apply a cementitious render

reinforced with galvanized mesh.

INTERNAL FIXING: it is possible to fix the material

directly on cellular or expanded concrete by applying

beforehand a coat of PRIMER G diluted 1:1 with water.

ASSESMENT AND PREPARATION OF

SUBSTRATES:• Cementitious screeds and screeds based on special

binders

• Smoothing compounds

• Old ceramic or natural stone floorings

• Concrete

•Wood, Chipboard, PVC, linoleum or rubber floorings, metallic surfaces

• Plaster

• Gypsum or anhydrite

• Blocks of cellular cement such as Gasbeton

• Old painted surfaces

ALWAYS REMOVE old paintwork before

fixing tiles.

If it is not removed, the bond of the

covering is not guaranteed over a long

period of time, because the paint may

soften and flake off which would lead to

detachment of the tiles.

THE EUROPEAN STANDARDS

• EN 12004ADHESIVES FOR CERAMIC TILES: DEFINITIONS AND

SPECIFICATIONS

• EN 13888GROUTS FOR CERAMIC TILES: DEFINITIONS AND

SPECIFICATIONS

• EN 12002ADHESIVES FOR CERAMIC TILES :

DETERMINATION OF THE TRANSVERSAL

DEFORMATION OF CEMENTITIOUS ADHESIVES

Standards that define the tests methods to determine

the characteristics of adhesives and grouts

Thank You.

STONE

MATERIAL

STONE

MATERIAL

CLASSIFICATION

According to Italian Standard UNI 8458“Terminology and classification of stone materials”ornamental rocks can be classified in four different

categories :

MARBLEMARBLE

GRANITGRANIT

TRAVERTINETRAVERTINE

STONESTONE

AGGLOMERATES

MARBLE, GRANIT OR QUARTZ CRUSHED

+

POLYESTER RESIN, EPOXY RESIN OR CEMENT

PROBLEMS OF STONE MATERIAL

• DIMENSIONAL STABILITY TO WATER AND TO

HEAT

• SENSITIVITY TO HUMIDITY THAT CAUSES

STAINS OR EFFLORESCENCES

COEFFICIENT

OF THERMAL

EXPANSION

(°C-1)

∆T

(°C)

EXPANSION

(mm/m)

AGGLOMERATE

MATERIAL35 • 10-6 70 2,45

NATURAL STONE 7 • 10-6 70 0,49

Dimensional stability laboratory

Simulation test with humid felt

Detail of the sensors positioned on slab

In the first 6 hours of measuring it is possible to

register reduced or very strong movements, so

that the materials can be classified in three

categories:

CLASS ACLASS AMovements inferior

to 0,3 mm after 6

hours

CLASS BCLASS BMovements between

0,3 mm and 0,6 mm

after 6 hours

CLASS CCLASS CMovements higher

than 0,6 mm after 6

hours

0 3 6 9 12 15 18 21 24

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

Movimento (mm)

Tempo di prova (h)0 3 6 9 12 15 18

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

Tempo di prova (h)21 24 0 3 6 9 12 15 18

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

Tempo di prova (h)21 24

Bonding test

(for slabs belonging to Class B or C)

Warping of a slab in Verde Alpi because of the application

carried out with normal-set cementitious adhesive

CASE HISTORY

Tests No. class A class B class C

455

Natural

stones

367

(80,7%)

37

(8,1%)

51

(11,2%)

249

Cement

agglom.

87

(34,9%)

95

(38,2%)

67

(26,9%)

285

Resin

agglom.

180

(63,2%)

59

(20,7%)

46

(16,1%)

989 in

TOTAL

634

(64,1%)

191

(19,3%)

164

(16,6%)

class C

17%

class B

19% class A

64%

Class B +

class C =

36% !

STAINS OF STONE MATERIALS:

CAUSES

• Presence of rising damp from substrate in

absence of a vapour barrier

• Installation carried out on a screed with very high

residual humidity

• Installation carried out by the use of a traditional

mortar bed or with a non fast-setting cementitious

adhesive

• Thickness of thin material

• Deposits of “iron” substances present on the back

of the marble after the working process.

• High concentration in the stone of iron sulphide

(FeS2), that is pyrite, which, in contact with water

and oxygen, transforms, after different chemical

processes, into iron hydroxide; this last one, in

form of solution, seeps into the stone porosities

and is visible on the surface as yellowish stains

that can in the time affect the whole surface and

become always darker.

STAINING OF WHITE CARRARA MARBLE

• In this specific case, the presence of “pyrites” in the structure of the marble may lead to a complete colour change.

Installation of floorings and coverings with improved

cementitous adhesives (C2) or improved reactive

adhesives (R2), of optional class F-T-E, according to the

norm EN 12004 depending on the type of installation to

be carried out, of the material to be laid and on its

belonging class

Grout the joints with:

Cementitious mortar classified as

CG2 according to EN 13888

(possibly mixed with polymeric admixture)

or with epoxy mortar

classified as RG

according to EN 13888

Thank You.