natural granite

All you need to know about natural granite tiles

Granite is an igneous rock composed of mostly two minerals: quartz and feldspar. It is an intrusive rock, meaning that it crystallized from magma that cooled far below the earth’s surface. Its name is derived from the Latin word ‘granum’, which means ‘grain’, a reference to the easily-seen minerals in the rock. Much of the earth’s continental crust is made of granite and it forms the cores of the continents. Granite also is found below much of the rest of the middle of the continent. Buried under hundreds of feet of sedimentary rocks and glacier-deposited sediment, you’ll find what’s called basement rock. Granite can make up much of this foundation of the continents.


HOW DOES GRANITE FORM?

Given the abundance of granite, it’s not surprising to learn that geologists still have many questions about how it forms. Sure, it comes from molten rock, but just where did all that magma come from? And how far below ground did the magma crystallize?

Probably the most widely-accepted idea (at least at the moment) is that granite magma originated from a mechanism called partial melting, in which rocks of a very different composition melt in stages and the initial magma is enriched in the minerals that melt first. But where that happens – whether in the mantle or in the lower lithosphere – remains unclear. Regardless of where the magma formed, it probably migrated upward before collecting in large magma chambers prior to cooling and solidifying.


 

MINERAL COMPOSITION

Although the term ‘granite’ or ‘granitic’ is sometimes used as a general description for any intrusive rocks that look like granite, the name really applies to a rock with a very specific mineral composition. Granite is composed mostly of two minerals: quartz and orthoclase feldspar (a potassium-rich variety of feldspar). Quartz must make up at least 20% of the rock and orthoclase at least 35%.

If either of those criteria is not met, then the rock is not granite. In fact, those are the only two minerals that have to be in the rock! The remaining rock (up to 45%) can be one or more other minerals, such as plagioclase feldspar (a sodium-rich variety), hornblende, pyroxene, muscovite, or biotite (the last two are kinds of mica).


FACTS ABOUT GRANITE

  • Granite is one of the hardest substances in the world. In fact, the only thing that is harder than granite are diamonds. This is what makes granite so sought after as a countertop. For the simple fact that it is extremely durable and it cannot be damaged by scratching. You can cut on a granite countertop because it is so hard and durable.
  • Granite comes in many different colors thanks to the composition and minerals within the rock. The specks, veining patterns & colours are unique. In other words, no two granite stones are alike.
  • It is the only igneous rock that is widely spread throughout the world and produced from volcanic magma that geologists named “granitic magma”.
  • The chemical composition of all granite differs as per their country of origin. This is one of the reasons that granite is available in various different shades and colours.
  • The granite stone is classified on the basis of three categories namely; colour, country of origin and chemical composition and interestingly is that these three categories are inter related.
  • As compared to marbles granite is a far more durable and robust stone and this characteristic is due to the presence of quartz in its chemical composition.
  • It can tolerate more than a hundred degrees of temperature easily because it is built from volcanic magma.
  • The slabs of granite are more susceptible to breaking if they are carrying hair line fractures.
  • The cost of granite varies country to country. The choice of a rare colour like red and blue in granite stone is far costlier than regular colours.

 


In addition to the quartz and feldspars, granite may also contain other minerals such as mica, horne blend and occasionally pyroxene.
Compared to calcareous sandstones, marble and limestone, granite is not an acid soluble stone and is much more resistant to the effects of acidic solutions, rainwater or cleansing agents.

In general, igneous building stones, such as granite, have a more inert composition; show much lower rates of deterioration; have lower water absorption, and are harder than marbles, limestones and sandstones.

 


PROBLEMS AND DETERIORATION

BLISTERING:

A swelling on the surface followed by a rupturing of a thin, uniform skin.  Although most common on sandstone, this problem may occur with granite.  It is typically caused by de-icing salts and/or ground water, therefore it is usually localized near ground level.
This condition may stabilize and remain constant, however it frequently precedes additional problems such as spalling or exfoliation.

There is currently no established treatment other than rectifying the conditions that cause the blisters, spalling, or delamination.


CHIPPING:

The separation of small pieces or larger fragments from a masonry unit, frequently at the corners, edges or mortar joints is called “chipping.”  These fractures are generally caused by the impact of deterioration and repairs, especially the use of too hard a pointing mortar, or by accident or vandalism.


CRACKING:

Visual symptoms of cracking include appearance of narrow fissures ranging from less than 1/16 to 1/2 inch or more wide in the stone. It results from a variety of causes, for example, structural overloading due to settlement, and the use of too hard a mortar mix or a flaw in the material.  Minor cracking may be no problem in and of itself, but it can also be an important early indication of structural problems.

Cracks can be a point of entry of water into the interior of the stone, promoting salt migration.  Repairs include patching and replacement.


DETACHMENT:

This is not a failure within the material per se but a failure of the construction system, i.e. the connectors and/or joints.  The definition implies that the failed component survives intact and
may be re-installed using appropriate mechanical techniques.

The failure of structural anchors or metal connectors which lead to detachment may be caused and/or accelerated by the penetration of water into the structure behind the stone, causing rust and corrosion.  Adequate pointing and caulking will prevent leakage and penetration of water into the structural system.


EFFLORESCENCE:

The appearance of a whitish deposit locally or uniformly over the surface may be efflorescence, the surface deposition of soluble salts.  There are numerous sources for the soluble salts which create the hazy appearance; salts can originate from mortar, improper cleaning agents, rising damp, de-icing salts, chemical landscaping treatments or air pollution.

Efflorescence can be a salt residue resulting from improper chemical cleaning, i.e. too strong a chemical cleaner or inadequate rinsing.  Since it can be an indication of water problems, salt migration and/or sub-florescence, efflorescence should be considered a symptom which should be investigated to identify the source of the soluble salts and/or the moisture.  Corrective action should then be taken to eliminate both if possible.

Some efflorescence may occur naturally with new stones, mortar and installation materials.  Normally, this efflorescence will be removed by natural rain and weathering processes and/or by regular washing.

The new or continued appearance of efflorescence is a stronger indicator of problems like rising damp or inappropriate cleaning methods.


 

FLAKING:

This is an early stage of more serious problems such as peeling, exfoliation, delamination or spalling and is evidenced by the detachment of small flat thin pieces of the outer layers of stone from a larger piece of stone.

Flaking is usually caused by capillary moisture or freeze-thaw cycles which occur within the masonry.  Applications of water-repellent coatings may result in flaking by trapping moisture beneath the surface.

The problem can also occur due to sub-florescence, so that if flaking occurs, the area should be inspected closely to determine if salt crystallization is occurring in the flaked areas.  The symptom will be a thin coating of a whitish deposit where the sub- surface is exposed.

Observations should be made as soon as possible or inspection be directed to where flakes have not yet separated, because evidence of sub-florescence may be washed away after the subsurface is exposed.


PEELING:

Peeling is flaking away of the surface from the substrate in strips or layers.  It can result from the improper application of masonry coatings which result in failure of the coating and/or stone surface.

Encrustation of the surface caused by chemical reactions with environmental elements may also peel or flake along the plane of interface with stone.


RISING DAMP:

Rising damp is the suction of ground water into the base of masonry through capillary action.  Moisture is drawn up into the stone and the level may rise and fall due to conditions of temperature; humidity; site grading; absence or failure of damp courses, and/or treatments to the masonry surfaces which affect evaporation.

During active wet periods, rising damp may be visible as a darkening of the stone along the base at ground level.  Due to the continuous changing of the moisture level due to varying exposure conditions, staining or efflorescence may be visible at a range of several feet up from the ground.

Continued rising damp can lead to more severe problems of flaking, peeling and/or spalling, but the correction of the problem requires the elimination of the source of water or the interruption of its path into the stone by physical or chemical damp-proofing.


SUB-FLORESCENCE:

This is a potentially harmful internal accumulation of soluble salts deposited under or just beneath the masonry surface as moisture in the wall evaporates.

The source of the salts can be de-icing salts; chemical cleaners or landscaping products; mortar and/or air pollution.  The salts get into the stone dissolved in rainwater or groundwater via natural absorption, rising damp or poor joints.

The build-up of salts and their subsequent crystallization can create substantial pressures with the masonry, eventually causing pieces to break off along the planes of deposition.  Efflorescence at the surface is an important early indication that sub-florescence is a possible hazard.
Techniques for mitigating the problem include poulticing, removal of identified salt sources, elimination of moisture in the stone and damp-proofing.


STAINING:

A variety of stains may appear on stone, each having different characteristics and requirements for removal.  Staining can be caused from such sources as

Corroded iron or steel connectors within the masonry
Salt crystallization (efflorescence)
Run-off from bronze or metal sculpture/ornament
Accretion of particulates (dirt, soot, etc.), and Graffiti.


GRANITE SELECTION

Sardo  – 600x1200x15mm – Flamed and Brushed

Sardo is a popular granite with large grey, white and black flakes. This stone is especially suitable for exterior/ interior wall and floor applications, stairs and other design projects. Each stone has its own exclusive movement

Imperial White 600x1200mm  – Flamed and Brushed

A light grey granite with small black flakes. This granite is made up of quartz, feldspar, mica, pyroxene and hornblende and is one of the more famous types of granite in the world.

It is widely used for floor and wall coverings, paving stones and countertops

Venetian Pearl 600x1200mm  – Flamed and Brushed

Venetian pearl is a light grey granite with fine uniform black speckles.

It can be used in interior and exterior floor and wall applications for its affordable cost and color consistency.

Ash Grey 600x1200mm – Flamed and Brushed

G654 granite is fine-grained, dark grey granite from China, It’s among one of the most popular granite in the stone world. It is mainly used for flooring, wall cladding and kitchen counters.

Other universal names include sesame black, sesame grey, Padang dark, Padang Dunkel, China Impala. Dark Barry grey, Neu Impala, Flake grey, Padang Scuro

Fantasy Stone  600x1200mm  – Flamed and Brushed

An exclusive grey granite with natural black and dark grey veining. Mainly used for flooring and wall cladding. Each stone has its own exclusive movement.

 


INSTALLATION  -BRIEF OVERVIEW

A lot can go wrong if the installation is not according to the adhesive manufacturer’s specification.

Definitely a good quality quick set adhesive to be used.

The adhesive to be well spread on the floor area.

Butter the entire back side of the tiles with a thin coat of adhesive – this to form a barrier for any possible moisture coming through from the bottom of the tile.

No spotting of adhesive whatsoever – we have found that in most cases it can be seen through the tile!!  A MAJOR PROBLEM IN TH PAST.

Do not butt join the tiles – joint to be approximately 3mm

Use quarry grout.

Surfaces to be well cleaned during the grouting process and all excess to be removed to avoid any picture framing.


CONSULT THE WEBER LAYING SPECIFICATION FOR FURTHER DETAIL


CLEANING AND SEALING

In some cases the varieties of Granite take longer to dry than others.

Only recommend penetrating sealers, but twin pack polyurethanes can be used internally.

Colour enhancing only available for internal tiles.


You must also be well aware of the fact that Granites contain natural minerals which include iron, copper etc.

If the incorrect detergents are used for cleaning, a problem may arise where the tiles “yellow” ie rust – this possibly due to spirits of salts being used or the tiles were not correctly neutralised after the acid wash.

You may also find “oily” marks in the joints and picture frames – this caused by poor rinsing and not neutralizing correctly.


CONSULT THE TILE SPEC SPECIFICATION FOR FURTHER DETAIL.


As a general rule:


Do not use acids or acid based cleaners to maintain granite flooring.

It is advisable to consider applying a Stain Ban sealer to all natural stone surfaces. Stain Ban is designed to penetrate below the surface of the granite, bonding to the stone and coating the individual minerals below the surface of the stone.

 Water, oil and dirt are restricted from entering the granite, yet it allows the stone to “breath. Flamed and Honed granite tiles can be sealed for internal or external areas with The Tile Doctors Sealer. Polished granite tiles require no sealing, and only regular routine maintenance is needed in the form of sweeping
When sealing your granite, for internal, we recommend every 3-5 years and for external, every 2 years.