By Joe Simpson

Ongoing research and development has been driving the evolution of sealants, adhesives, grouts, and after-care products for the stone industry. These technical advances, mostly incremental but with the occasional step-change, seek to address on-site issues such as speed of installation, challenging substrates, sound reduction, grout haze, and coping with movement. At the same time, some of the new formulations are also trying to address macro issues, such as sustainability, contractor safety, and air quality.

In recent years, this has led to the development of gel-based formulations, fibre-strand reinforcement and nanotechnology. There can also be commercial benefits, as some of the latest products on the market are also multi-functional, offering ideal combinations of rapid setting, longer pot life, adjustability, multi substrate compatibility, and suitability for a wider range of surface materials. For the distributor or retailer, this can reduce inventory requirements, and provide a clear and simple-to-understand sales story for customers. For the contractor, they can also mean fewer products on site, and better productivity.

One area of product development that has caused some confusion is lightweight adhesives, something at the core of Mapei’s product development strategy. The company’s philosophy is to constantly improve and enhance the quality of the its adhesives, while endeavouring to improve their environmental impact. Lightweight adhesives are just one component of its approach towards sustainability.

However, convincing potential buyers of the virtue of these products can be difficult as the manufacturing raw material costs are greater than traditional fillers. So the initial purchasing price always appears higher. Mapei’s marketing campaign may need to to explain the benefits, while debunking common misconceptions.

For instance, Mapei stresses that lighter materials do not mean less volume of product. In fact, they can deliver more volume for less weight. If you compare Mapei’s Ultralite S2 15kg with a traditional S2 cementitious adhesive with a traditional powder and liquid mix (a 20kg bag of powder and approximately six litres of a latex additive), the latter delivers 26kg of product that will cover around 5sqm using a standard bed. In contrast, Ultralite S2 delivers 15kg of material that will cover around 7sqm using a standard bed when mixed with six litres of water.

Regarding transporting these different materials to site for a 1,000sqm installation, the standard two-part mix would require 200 bags of powder and 200 bottles of liquid: seven pallets in total. With Ultralite S2, the same installation would require just three pallets.

To look at this on a larger scale, one million square metres of stone tiling would require around 22,400 trucks with standard adhesive and latex additive, but just 11,700 truck movements with a lightweight adhesive. There would also be significantly less packaging waste: a huge environmental benefit.

It may be a hard sell, but the construction and building industry is slowly waking up to the need to take more considered purchasing decisions, and move away from a simple price comparison model. It could be a while for cost calculations to take into account that extra material brings down the price per square metre installed, and may also come with the bonus time savings, transport savings, and health benefits. But it seems likely that such considerations will become more influential in the future.

When it comes to stone adhesives, other factors becoming more influential include the percentage of recycled materials, such as glass and rubber, that can now be used to replace standard fillers in adhesive production.

For tilers, the constant trowelling of the adhesive takes its toll over the years. New lower density formations are claimed to be significantly easier to spread, reducing the incidence of RSI on the knees, hips, wrists, elbows, and shoulders of contractors.  It also means less lugging of materials on site, and they may even increase the speed of installation.

Mapei and St Gobain Weber are among the leading manufacturers that have formulated adhesives to reduce dust production during mixing. This has enormous benefits to the installer’s health, reducing the risk of lung damage from fine dust particles.

Every manufacturer offers a rapid set adhesive that enables floors to be walked on and grouting to be carried out more quickly than with a standard set product. With conventional cement-based fast set (C2 F) adhesives, the specifier must take into account the type of substrate and whether it is flexible or not. Classified as C2 FTE S1, Kerakoll’s Biogel Revolution — suitable for natural stone such as marble  — with gel technology that can be used on any type of substrate, including those that are deformable by up to 2.5 mm. The pot life at 23°C is one hour, and it is ready for foot traffic and grouting after three hours.

For applications where an R2 adhesive is more appropriate, Kerakoll offers a hybrid-gel adhesive, Biogel Extreme, which can fix any material to any substrate even in the most extreme conditions. It is also solvent-free and non-toxic, unlike traditional epoxy-based reactive resin adhesives.

The adhesive strength (4.5N/mm2) is claimed to be 500% superior to a Class C2 cement-based adhesive after 24 hours, and ten times more deformable (> 50mm) than a Class S2 cement-based adhesive. It is also easy to spread, being far less viscous than a polyurethane adhesive. The pot life at 23°C is 110 minutes, with an open time of 180 minutes, but it is still ready for foot traffic or grouting after four hours.

Sika-owned Construction Technologies Australia (CTA) is an Australian-based manufacturer of stone and tile adhesives and associated products. The company formulates all products (where possible) around the Australian “Green Star” code. Typical is Prohesive Megalite: a high-performance polymer-modified, multi-purpose, high flexibility, high strength lightweight adhesive. Ideal for setting large format stone or tile, it offers non-slump performance for large format floor installations. Recommended for application up to 20mm thick, it is said to be 40% lighter than traditional cement-based adhesives; with a 13.5kg bag covering a greater area than a 20kg bag of traditional cement adhesive. It is suitable for use in areas that are permanently damp, subject to thermal shock, and high mechanical loads.

Prohesive Ultrapro is a lightweight, fast setting, high coverage, polymer-modified, flexible, cement-based adhesive that was developed for time-critical installations. The formula makes it easy to handle and it can be used for both internal and external applications. The anti-slump characteristics make it useful for installing large and heavy stone tiles.

Aqua Mix is a range of tile and stone care and maintenance products that has been owned by US giant, Custom Building Products since 2006. The latest range includes Aqua Mix KnockDown, a non-acidic honing powder that removes light surface scratches, moderate acid etching, and wear patterns to produce a flat, even and honed finish. It is suitable for treating polished marble, limestone, or travertine when a honed, unpolished finish is desired.

Aqua Mix Enrich ‘n’ Seal is a premium, no-sheen, enhanced-look, 100% polymer-solid, penetrating sealer formulated to darken, enrich, and highlight the character and beauty of unsealed natural stone. It can also be used as a pre-grouting sealer, and effectively seals and darkens the colour of grout joints.

In Australia, another respected name in stone care is Dry-Treat. It offers a portfolio of impregnating sealers and specialist cleaners that are engineered to protect and maintain a wide range of porous surfaces, including all types of natural stone. Dry-Treat provides all the options needed to keep stone protected, while also retaining or enhancing the desired look.

Dry-Treat said its impregnators offer far more than mere oil- and water-based stain protection, since deeper penetration and permanent bonding technology means protection from more serious issues, such as efflorescence, picture framing, and salt or freeze-thaw spalling.

A stand-out example is Stain-Proof Original: an impregnating, invisible, and breathable sealer that provides long-term protection for natural stone against water- and oil-based stains and damage caused by water and dissolved salts. It is suitable for a wide variety of indoor and outdoor applications including façades, floors, walls, countertops, showers, swimming pool surrounds, and patios.

Pictured: Mapei’s Ultralite S2 delivers 15kg of material that will cover around 7sqm using a standard bed when mixed with six litres of water