ARDEX SD-T Self-Leveling Concrete Floors

 

We also have extensive experience in the installation of self-leveling concrete toppings including ARDEX® SD-T. and Dry Tek™. The Stonekfratz© team performs all aspects of the installation process begining with the surface preparation phase, leveling and filling cracks in the substrate, applying the primer/epoxy, pouring the self-leveling topping, and applying the sealant.

 

Stonekraftz© has even used sophisticated polishing equipment to remove stains and imperfections in the Ardex surface altering the appearance to provide the customer with a marble finish. We have faced the challenges of working with difficult cement and epoxy products.

 

What to Know if You Are Installing an Self-Leveling Concrete Floor

            Self-leveling concrete floor toppings such as ARDEX SD-T can be extremely challenging products to work with.  It is only through experience that one begins to develop and understanding on how concrete topping products like ARDEX SD-T actually behave.  After hearing the horror stories and seeing the results of failed installations, we decided to put together this brief installation tutorial to serve as a guide for contractors who are new to ARDEX.  We hope that it helps you avoid the disastrous consequences (i.e. lawsuits, bankruptcies, or worse) of improper installations.

Surface Preparation Prior To ARDEX Installation

Surface preparation is perhaps the most important step in the self-leveling concrete installation process.   ARDEX SD-T can only be installed on freshly poured or properly scarified concrete (or on top of existing ARDEX SD-T).  Imperfections in the substrate surface (i.e. cracks, holes, etc.) will show through the ARDEX SD-T topping and lead to cracking.  Likewise, any building material (i.e. paint, joint compound, adhesives, etc.) will prevent the ARDEX epoxy primer form bonding to the substrate. 

In typical installations in and around New York City, the installing contractor will have to lay the self-leveling concrete on an existing concrete floor.  The process of scarifying is more often than not the most time-consuming and difficult part of the installation.  We recommend using a shot blaster such as the ones available for rent at Niagara Machine Company.  

 These powerful machines fire small steel pellets known as “shot” (similar to the shot in a shot gun shell) into the surface.  The shot blaster is attached to an industrial vacuum that captures the dust and debris removed from the surface.  The shot blaster is designed to recycle the shot, but a small amount of shot usually escapes during the shot blasting process.  Most equipment rental companies, such as Niagara, will provide you with a magnetic broom to recover any shot that escapes.  This shot is then put back into the shot blaster.  If done correctly, you should only have to shot blast the surface one time; however, certain trouble spots may require a second pass.  Always wear eye, ear and respiratory protection when operating this equipment.

There may be many areas such as corners and other hard to reach places that will require the use of a hand held grinder.  Proper surface preparation in these areas is a key to successful installation.  Any debris left will prevent the epoxy primer from bonding to the surface.  The ARDEX will eventually loosen and begin to crack.  To reduce the amount of dust in the air, the grinder should be equipped with a dust shroud and attached to an industrial vacuum.  There are also special scarifying blades designed to remove debris without wearing away the substrate.  Hand grinding is both dangerous and uncomfortable.  Grinder operators should always wear eye, hand and respiratory protective equipment. 

Asbestos is present in many old concrete floors.  During the surface preparation process, asbestos and other harmful substances in the substrate may be disturbed and contaminate the surrounding air.   Always wear respiratory protection while scarifying.

Substrate Inspection

Once the entire surface, including corners, is scarified, a visual inspection must be performed.  Carefully check every inch of the substrate for building materials or other contaminants that could potentially jeopardize the ARDEX SD-T installation.  A small piece of debris left on the surface could prevent the primer from bonding and lead to premature cracking.

Installing the ARDEX Epoxy (EP 2000 Primer)

Once the entire surface has been properly prepared and all dust has been removed, an epoxy primer must be laid. Only use the ARDEX EP 2000 primer.  Single can easily cover 150 square feet.  The primer is installed with a paint roller.  The primer is an epoxy that is extremely difficult to remove and will cause burning when in contact with skin.  Always wear thick rubber gloves and long sleeves. 
The EP 2000 primer weighs about 10 lbs. and contains two parts.  The hardener (Part B) must be ruptured and mixed with the epoxy (Part A).  While one person is laying the primer, a second should be broadcasting fine dry sand on to the drying primer.  The sand should be less than 1/50 of an inch in grain size, or 98.5% passing sieve size #30 or #35 and must be broadcasted within 30 minutes of applying the primer.  A rule of thumb for sand amount is roughly 6 to 8 ounces per square foot.  The entire surface must be covered in sand.  When examining the floor after broadcasting sand, you should not see any glassy primer. Do not worry about using too much sand. This is a very common mistake that installers make.  The sand plays an essential role in the bonding process.  The primer if left to dry improperly (i.e. not enough sand), will dry smooth.  The ARDEX SD-T cannot bond to a smooth surface. Once the primer dries, the excess sand will be swept away.  The entire surface must be completely primed.   The failure to bond will cause cracks and imperfections, particularly pinholes in the ARDEX SD-T surface.

The primer must be given a minimum of 24 hours to dry.  Depending on the substrate condition and the amount of primer laid, drying may take longer.  Once dry, the surface must be swept clean of all sand.  All excess sand must be removed. This requires several sweeps.  
An additional inspection should be conducted to make sure that the entire surface has been primed.  A small spot left unprimed will become a trouble area where a crack will eventually form.  The crack will inevitably spread.  If unprimed areas are found, use a small paint brush to prime these spots and broadcast some sand to insure proper bonding.  Wait 24 hours and remove excess sand.

Pouring the Self-Leveling ARDEX SD-T Concrete Floor

The grueling surface preparation has been completed.  The EP 2000 epoxy has been laid.  You are ready to install the concrete topping.  Here is what you need to do:

Determine how thick the self-leveling topping should be
ARDEX SD-T may be installed from a minimum of ¼ inch to as much as 2 inches. A 50lb bag of will typically provide a ¼” coat on 25 square feet.  We do not recommend installing less than ½” of self-leveling topping especially if the substrate has excessive cracks and is generally in bad shape.  ARDEX SD-T is an expensive product that costs over $50 per bag.  If ½” will be installed, the cost for this material alone could exceed $4 per square foot.  This does not include other costs (EP 2000 primer, sand, installation equipment, etc.).  At times it is hard for customers to understand the costs involved.  If you are bidding a project competitively, be sure to emphasize the quantity of ARDEX SD-T you propose to install.    

The Proper Tools

ARDEX sells a general installation kit for its products.  The kit includes a large mixing bucket and a series of small buckets used for measuring water as well as the surface finishing tools.  The large mixing buckets can be purchased separately. The small measuring buckets have quantity measurements printed on the bucket label as well as a small slot that prevents the bucket from being filled above its predetermined limit.  These buckets are essential to guaranteeing the proper water to ARDEX ratios.  If you are installing ARDEX SD-T, you will only need the white 5 quart bucket.  Therefore, do not bring any other buckets to the jobsite.  There is another white bucket that measures over 6 quarts and could easily be confused with the 5 quart bucket.  Watered- down or dry material will not set properly.  Depending on the amount of square feet to be covered, you may need to have several mixing buckets.    

 

Set Up A Mixing Station

Stonekraftz recently poured a 10,000 square foot floor.  We poured the floor in two 5,000 square foot sections.  The mixing station required a minimum of six (6) workers.  Two (2) workers were assigned to each mixing bucket.  Prior to starting we calculated the amount of material required and opened the top of each bag of ARDEX SD-T and carefully lined the bags up next to each mixing bucket. This was done to facilitate the mixing process. An adequate source of water (a 55 gallon drum with a hose for refilling) was placed next to each mixing bucket.   

The material must be mixed with a high speed drill for a minimum of 2 to 3 minutes.  First water is poured into the bucket, next the self-leveling concrete is slowly added.  While mixing, the drill must be moved to all corners of the bucket to guarantee proper mixing.  Inadequate mixing will result in surface imperfections.  It is also important to have additional mixing buckets so that, while material is being transported to the finishers, the mixing process can continue.

 

Transporting the ARDEX SD-T

Two 50 lbs. bags of ARDEX SD-T plus water are normally mixed together in the mixing bucket.  This mixture weighs over 100 lbs. and must be transported quickly to the finishers who, depending on the conditions, could have less than 10 minutes before the line dries and the material sets.  Stonekraftz uses dollies to transport the material.  For the installation shown in the images, two transporters constantly brought fresh material to the finishers.

 

The Drying Process
ARDEX SD-T takes between 12-24 hours to cure.  But can be walked on after about 4 hours.  Although the data sheet says that a water based sealant can be applied a few hours after pouring, we recommend that you wait 24 hours before applying the sealant.

 

Applying the Sealant

A water-based concrete sealant can be sprayed on once the floor has completely cured.  Prior to sealing, the floor is vulnerable to staining from any liquid –even water.  ARDEX sells a product called Cement Guard, but any water based sealant can be used.  ARDEX recommends spraying the sealant on the surface and allowing it to dry.  A second coat should be applied after the first coat dries.  Be careful not to put too much sealant on the floor.  It could stain or cause spots.  It is best to lightly spray the sealant and spread it with a special mop to ensure a consistent finish.  The sealant dries fairly quickly; however, oils and solvents could still penetrate the sealant and stain the self-leveling toping.   

 

Epoxy Floors

 

We have faced the challenges of working with difficult cement and epoxy products. Epoxy floors may be more suitable for high-traffic installations where self-leveling concrete presents limitations. Epoxy floors are more resistant to oils, chemicals and solvents that tend to penetrate even the heavist sealants leading to stains and discoloration on the Ardex self-leveling concrete surface.

 

Artistic epoxy coatings offer limitless options for achieving an original finish and look. Give us an opportunity to provide you with a personalized concept to compliment your warehouse or office space..

 

Whether you require a new floor or repairs, through the use of designer concrete and epoxy, we can provide you with any industrical or artistic finish that you desire.