Sticking points in stone installation
Laticrete International’s technical services department highlights the various problems that can occur within the grout joint area of a stone tile surface and suggests solutions.
01 June 2011
STONE tile can be tricky to install and even trickier to maintain. Some of the main problems associated with installation occur because of improper grouting.
There are some major reasons why problems occur after the grouting procedure. These include rapid hydration of Portland cement-based grouts and the erosion of such joints.
Some job site conditions can contribute to the rapid hydration of Portland cement-based grouts. These include hot and/or dry environment, very absorptive stone, and heating, ventilation and air-conditioning (HVAC) systems in close proximity to the installation, draughts across it that cause it to dry out too quickly. All of these conditions can result in rapid loss of moisture which in turn can result in a problematic grout joint (such as powdering, cracking and eroded joints).
The causes of erosion of the joints can range from improper hydration of the grout due to environmental or site conditions to over-washing the grout or using too much gauging liquids with the grout.
Furthermore, some of the problems are associated with too much water either in the mixing or clean-up process.
Excess water in the grout leaves behind voids after evaporation, leading to shrinking of the grout in these areas.
Excess water also dilutes the strength of the Portland cement, resulting in a weaker grout joint.
Often, the grout selected is not appropriate for the specific installation. This, obviously, can lead to problems as well.
For, example, non-sanded grouts are typically designed to be used in grout joints up to 3 mm in width. If selected for joints wider than 3 mm, this grout is susceptible to shrinkage, causing it to become loose and either erode or flake out of the joint.
Problems can also arise if the grout joint varies in depth, colour and strength. One characteristic of Portland cement-based grout is that the slower it dries, the darker the colour will be; also, the larger the mass (or deeper the grout joint) the slower it dries. Therefore, an inconsistent depth of the grout joint can result in shade variations.
Efflorescence
The term ‘Efflorescence’ is frequently used to describe problems with stone tile setting beds and grout, resulting in the surface of the stone looking chalky and very unattractive. This occurs when soluble salts from the Portland cement-based setting bed, grouting material or the substrate are brought to the surface of the grout joints via capillary action when there is moisture present. Excessive water in the mixing and clean-up of the grout can also contribute to this problem. One excellent way to minimise efflorescence is to use a high-quality latex admixture for the setting and grouting system. These latex additives help to eliminate excess water.
Grout removal
When grout deteriorates, it simply must be removed. When removing and cleaning all loose or deteriorated grout, care should be taken not to damage the stone tiles. A good rule of thumb is to remove, at least, half the depth of the grout joint down to sound and stable material to ensure that the new grout will have enough space in the existing joint to achieve its maximum strength. Also, make sure that the grout is removed at an even depth.
Some of the methods to remove existing grout range from hand-held grout “raking” removal tools to dustless, diamond blade electric circular saw and even high-pressure water jet systems. The grout joints should then be washed to remove any dust or debris and allowed to dry.
Regrouting
To achieve the best results in Portland cement-based re-grouting, liquid latex should be used in place of water to mix the grout. This will produce a durable and longer-lasting grout. Using a liquid latex admixture will reduce the potential for weak, powdery joints; provide a more water- and frost-resistant grout joint, preventing damage to grouts from weathering, frost- and thermal-shock and minimising staining. It will also reduce absorption and improve flexibility and durability to make the grout more shock resistant. To ensure optimum performance, a high-quality grout sealer is recommended as is the use of proper installation techniques, which include following the manufacturer’s guidelines for mix ratios and clean-up procedures.
Latest methods
Cross-linked technology grout and epoxy grout re-grouting procedures generally provide superior performance to Portland cement-based grout. They offer many advantages as they do not contain Portland cement, which can lead to efflorescence or mottling and other problems associated with such grouts; and are very dense and have an extremely low porosity rate, which makes them highly resistant to staining. They also provide a uniform colour, reducing the risk of shade variations.
Epoxy grouts are chemical resistant and resist many acids, alkalis and corrosives. They are durable and will not crack or peel. In addition, they are easy to maintain as they have a smooth texture and are easier to clean. Also, they never require a grout sealer. Generally, the grout is as dense and durable as the stone itself.
“You’re only as good as your last project” is a well-known expression within the tile installation community. Proper installation practices will minimise ensuing grout problems. But in the event that they do surface, excellent procedures to remedy these situations do indeed exist.
One such epoxy grout is Laticrete’s Spectralock, a patented, high-performance grout that offers colour uniformity, durability and stain resistance with extraordinary ease of use. It is suitable for installation of ceramic tiles, glass tiles and stone in residential and commercial applications both for interiors and exteriors, for floors and walls, swimming pools, fountains and other wet area applications.
Laticrete is the world leader in the manufacture of high-strength shock and weather-resistant tile and stone installation systems and waterproofing products. For over 50 years, Laticrete system materials have been specified and used in important projects around the world under the most severe climatic conditions from the Arctic to the tropics.
In the Middle East, Laticrete has introduced modern technology, which is changing the way the industry used to install tile and stone in the region. The company has been providing solutions to the region for the last 25 years and has been associated with some of the most prestigious projects in the region including the Sheikh Zayed Grand Mosque, Emirates Palace hotel, and Yas Marina Circuit in Abu Dhabi; Burj Khalifa, Atlantis – The Palm, Mirdif City Centre, Mall of the Emirates, Dubai Airport and Dubai Metro, all in Dubai; Doha International Airport in Qatar; Bahrain International Airport; Muscat Golf Club in Oman; Al Hamra Tower in Kuwait; and Riyadh TV Tower and Saudi Aramco projects in Saudi Arabia, to name a few.
As a part of its continued commitment to this region, Laticrete set up a local production unit in a joint venture with RAK Ceramics, called Laticrete RAK Company in May 2003. From this regional base, Laticrete RAK serves the Middle East and Africa.
