Magnesite

Magnesite is a magnesium carbonate mineral with a chemical composition of MgCO₃. It is named after the presence of magnesium in its composition. Magnesite usually forms during the alteration of magnesium-rich rocks or carbonate rocks by metamorphism or chemical weathering. Magnesite is a specialised cementitious product that is based on Magnesium Oxychloride (or Magnesium Oxysulphate) cements.

The most common form involves the reaction between a Magnesium Chloride solution and Magnesium Hydroxide powder to form the cement binder. The finished product also contains a filling material which is commonly sawdust, wood fibres, cork or can also contain ASBESTOS. Colourants may have also been added. Magnesite Flooring is moisture sensitive and will gradually breakdown if it remains wet for an extended period. Magnesite will swell up and the filler can also rot and produce unpleasant odours.

The product is mixed and then poured onto the surface to be topped. Magnesite Flooring is normally at least 10mm – 25mm thick. But can get up to 50mm thick if two coats have been poured. Magnesite was applied to the top of concrete ground floors in unit blocks. It has been commonly used in homes built in the ’20s, ’30s and was still used up into the ’80s.

Magnesite, sometimes misspelt as Magnosite was commonly used as a floor topping or floor levelling product. Magnesite contains a very strong glue, when Magnesite absorbs water, the glue can leach into concrete floors and corrode steel reinforcement bars causing Concrete Cancer. There are thousands of buildings built in between the 1920s and 1980s with Magnesite Floor toppings that need to be removed.

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What Is Magnesite

If your home was built in the 1920s-1980s, it is likely that your home has Magnesite. Magnesite is a specialised cementitious product that is based on Magnesium Oxychloride (or Magnesium Oxysulphate) cements. The most common form involves the reaction between a Magnesium Chloride solution and Magnesium Hydroxide powder to form the cement binder. The finished product also contains a filling material which is commonly sawdust, wood fibres, cork or can also contain ASBESTOS. Colourants may have also been added.

Magnesite was commonly used as a Floor Levelling compound from the 1920s to the 1980s. Magnesite is not used anymore, but because it was present in a lot of older buildings throughout Sydney, it means that floor removal contractors will come across it quite often, so knowing how to deal with it when the issue comes up is very important.

Magnesite is a form of cement, created through magnesium oxychloride. What makes Magnesite different from normal cement is that fillers and aggregates such as wood chips or sawdust have been added into it sometimes it may also have ASBESTOS. Magnesite was mainly used in Sydney, as a slab topping or an underlay to carpet and other forms of floor covering.

Magnesite is extremely rich in chlorides, resulting in problems of sweating, diffusion of chloride ions into the concrete substrate and metal corrosion, usually seen as lumps appearing below the carpet or cracks in the floor tiles.

There are many issues with having a Magnesite in your property which is why it is now recommended to remove it.

Magnesite is not a floor covering an individual unit owner would have installed. It would have been laid to level the slab and act as a soundproofing agent. It doesn’t get used anymore, due to its destruction of concrete slabs through Concrete Cancer, its general lack of waterproofing and it is known to contain to possibly contain ASBESTOS.

(It can be extremely dangerous to your long-term health, to remove if you don’t take the proper precautions while doing it, only a licensed specialist should ever attempt it).

Because Magnesite is water-soluble, it will return to its previous state should it be exposed to enough water. Magnesite is also quite flexible, meaning that it is not suitable to be overlaid with a smoothing compound, making it unsuitable to be used with all types of floor covering.

What Is Magnesite Used For?

Magnesite was used quite a lot in the flooring industry in the past and it is the properties that are often thirty or more years old, these older properties could still Magnesite present. Magnesite screeds were predominantly used in industrial buildings as it was known to be resistant to oil spillages, but are also often found it unit blocks and apartments.

Because Magnesite is water-soluble, it will return to its previous state should it be exposed to enough water. Magnesite Floors are also quite flexible, meaning that it is not suitable to be overlaid with a smoothing compound such as ardit, making it unsuitable to be used with all types of floor covering.

Although Magnesite Floors were quite a popular subfloor product many decades ago, the introduction of more modern, safer and more durable subfloor products has meant that Magnesite Flooring has fallen from favour.

When building contractors do discover a flooring screed that contains Magnesite, the chances are that it was installed many decades ago and is now showing definite signs of wear and tear. The best thing to do in this case would be to carefully remove the Magnesite Flooring and lay a new floor in its place.

Magnesite Flooring Removal will clearly take some time, but by laying a new damp proof membrane and a smoothing compound capable of offering a deep fill to replace the Magnesite, will mean the subfloor is far more suitable for modern use and will remove the risk of Concrete Cancer damaging your subfloor.

Magnesite is often mixed with concrete making it extremely difficult to remove even with the strongest team and specialized heavy demolition equipment such as a hydraulic jackhammer. The dust that is released from Magnesite when it is removed can be extremely dangerous to breathe in as well, making specialized safety equipment a MUST!

Magnesite has been commonly used in homes built in the 20s-80s. Just like many other asbestos-containing building materials, it was a useful chemical for a range of materials but unfortunately, the time has developed it into a health hazard, as well as a hazard to the building structure as it can cause Concrete Cancer.

For more information on Magnesite please visit:
Magnesite Flooring Removal

Is Magnesite Considered Dangerous?

to put it simply, yes Magnesite is considered dangerous to the structure and your health.

It is important to determine whether or not your home has Magnesite because this type of flooring is unsafe and should be replaced. Floors that were made from Magnesite are prone to getting damp since they do not remain moisture-proof.

When this occurs, the chlorides that are in the Magnesite end up seeping into the concrete that is beneath the topcoat. If it is bad enough, it can even corrode the reinforcements of the floor or corrode any water or gas pipes that may be present. Since Magnesite is water-soluble, that means that it will always return to its previous state if it exposed to enough water. So what does this mean for homeowners

Magnesite Floors are tricky to work with especially if you are trying to refurbish or renovate your home. Since Magnesite is flexible, it is not a suitable material to simply be overlaid by a smoothing compound. It is also not a good material to be used with some types of floor coverings. Something flexible such as carpet can be successfully used but if a more resilient covering is used, then problems are likely to occur.

Due to the fact that Magnesite was used in old homes, it also means that by now, your Magnesite Floor might not be in the best of shape and is likely showing signs of wear and tear. If this is the case, the best solution is simply to dig out the old material and replace it with a more resilient product.

The Affects That Magnesite Has Had On Sydney

Up to 90 percent of apartments built between 1960 and 1980 have Magnesite-related defects, according to experts. Louie Douvis.

Magnesite, which was commonly used as a floor topping or levelling product, contains glue. When Magnesite absorbs water, the glue can leach into concrete floors and corrode steel reinforcement bars, causing the concrete to expand.

The City Futures Research Centre at the University of NSW said that in NSW alone there were more than 14,000 strata schemes containing more than 186,000 lots or units registered between 1961 and 1979 which may contain a Magnesite Floor.  Peter Johnsson, associate principal with engineering consultancy firm ACOR, said up to 90 percent of apartments built during that period had a Magnesite Floor, particularly those in Sydney’s eastern suburbs, northern beaches, and western suburbs.

“The cost to fix this issue can range from $30,000 for an apartment on the low side to over $100,000 today,” Mr. Johnsson said.

Marton Marosszeky, director at BCRC, a group of specialist consultants in materials for construction, said owners of older apartments needed to be aware of the problem. “It’s a looming problem that’s coming towards us at a fast rate the moment,” he said. There are thousands of buildings built in that era with Magnesite. This could potentially eclipse the cladding issue.

But because it’s hidden and slow to manifest, it’s not getting a lot of attention.” Mr. Marosszeky said one of the Magnesite Floor-related jobs BCRC was working on in Sydney involved a 64-apartment building where all units were affected Signs of Magnesite Floor damage include cracked tiles and floors that bulge over rusting steel bars.

“The owners will have to spend up to $2 million to fix this problem,” he said.

“They’re spending millions of dollars rectifying a problem caused by a defective building material that is no longer in the market for the last 30-odd years.”

Unlike the cladding issue, which prompted government and insurance industry intervention because it involves newer buildings, owners of older apartments with legacy problems will have to shoulder the cost. “You could argue that Magnesite is similar to the faulty materials like flammable cladding, but because it’s not a new building, it’s been built at a lower standard in the old days, there’s no current pressure for the government,” Mr. Johnsson said.

Magnesite A Costly Issue Plaguing NSW

“In those days, apartments were built quickly and builders didn’t take time to make the floors perfectly flat with the concrete.

“The Magnesite Floor used to make the floors nice and flat was filled with sawdust and cork held together by glue. Now the glue was the problem because it was made of magnesium oxychloride in the Magnesite Floor.”

Magnesite Floor absorbs water and dissolves the chloride in the topping. When the chloride leeches to the steel bars reinforcing the floor, it corrodes them.  Mr. Marosszeky said the corrosion causes the concrete to expand by as much as eight times the volume of the original steel.

These expansive forces rupture the concrete, lifting the concrete just as a tree root lifts a footpath as the roots expand, Which is why its best to remove your Magnesite Floor ASAP. Magnesite Floors that are damage could show up as hollow sound on tiles, cracking of tiles and bulging of the carpet over the rusting steel bars.

Because of the slow corrosion, the symptoms aren’t visible until the damage is already widespread.

“Usually, when it’s discovered, the affected area that you can see is nowhere near the extent, because it’s a massive hidden problem in the concrete,” Mr. Johnsson said.

“So you’ll be looking at least two to three times the amount that is visible on the surface that will require repair. So when you see lumps on the floor, or corrosion rust stains on the concrete, the problem is already there.”

Because it is a structural issue, ignoring it is not an option.

“If you leave it for too long the bars simply get eaten away and then structural strengthening has to be undertaken, adding very significantly to the remedial cost,” Mr. Marosszeky said. “If you let it go, it can cost more than $1000 per square meter to remediate the problem, so stay alert and get help as soon as you detect any issues.”

“In the worst cases, the building will collapse. You have to fix it because it’s a structural problem.”

Please do not attempt to do this, it is NEVER a good idea to install ANY type of flooring system over Magnesite (its quite common for someone to attempt to install a new floor on top of Magnesite only for the new floor to start having issues due to the Magnesite bubbling up which will cause your new flooring system to fail and start to pop up.

Once you have removed your old flooring system and have revealed Magnesite , even if it does not look damaged it should always be removed. This will prevent the Magnesite from:

– Causing tens of thousands of dollars in concrete cancer damage to your concrete sub floor.

– Failure of your new flooring system.

– You can catch any issues early by removing the Magnesite it gives you the chance to inspect your concrete slab to make sure any issues are fixed early.

– No floor installing company will give you insurance or warranty on your new install if there is Magnesite.

– Magnesite will devalue your property rapidly.

– Magnesite can be harmful to your health (especially if you have children or pets!)

– Because the Magnesite has most likely been laid over 50 years ago, it will already be showing signs of wear and tear, which means it should always be replaced with a more suitable product.