TED is a small nonprofit devoted to Ideas Worth Spreading. It started out (in 1984) as a conference bringing together people from three worlds: Technology, Entertainment, Design. Raghava was one of the lesser-known and less-academic speakers at the TED Conference last month in Long Beach, CA. His engergy and spunk captured the TED audience’s attention as perhaps no other speaker did. He did nothing more than tell his story, which he said is one of extreme highs and lows. It is a tale of several lives wrapped into one. Please watch the video clip below. I am sure many of our decorative concrete contractors (or artisans) can learn some thing from this video.

I found that as an Artist, Raghava’s work is great, as a human being the sense of spreading happiness is touching. Now living in Brooklyn, NY, Raghava says he has found some of his most rewarding work in teaching yound childen to draw. Like we say in our Bob Harris led decorative concrete workshops, he says “I teach them to enjoy the process and try not to create anything perfect”.

Please feel free to live your comments.

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Surface Preparation

Acid Staining and Sealed

Acid staining concrete produces rich, deep, translucent tones unlike paints or coatings that produce a solid, opaque effect. Depending on the color and application techniques used, the results can mimic everything from polished marble to tanned leather to natural stone or even stained wood. The chemical stains (or acid stains) react with the concrete’s lime content and produce the color. If the concrete surface is painted or sealed, acid stains cannot penetrate the concrete and react with the lime. Therefore, a concrete surface that is painted or sealed cannot be acid stained.

Do you have to remove the paint or sealer from the concrete surface to acid stain it?

Not necessarily!

With the advent of latest acrylic polymer modified concrete, it is possible to apply a thin layer (1/8inch thick) of concrete over an existing painted or sealed concrete surface with minimal surface preparation. Please find below typical steps involved in applying a micro-topping / concrete overlay and acid staining over a painted or sealed concrete surface.

1. Run a sander with 60grit sanding screen over the entire surface. To ensure that the paint or sealer is bonded to the substrate, run the sander for at least 1 hour for every 1000ft².
2. Rinse the floor with mild detergent and allow it to dry completely.
3. Apply a liberal coat of acrylic primer, Cp1000.
4. Allow this primer cure overnight (at least 10 hours).
5. Apply a second coat of acrylic primer, Cp1000. The second coat needs to be applied just to damp the surface.
6. Once the primer turns clear and it is dry to touch, it is ready to accept the concrete overlay.
7. Apply the polymer modified concrete overlay, Pentimento at 1/8inch thick. It is a retrowelable concrete overlay…which gives a very smooth concrete finish.
8. After 24 hours of the curing or polymer concrete overlay, it is ready to take acid stains (chemical stains).
9. Spray the acid stain, Patinaetch at the rate of 250ft²/gal. Allow it to react for with the lime in the concrete for at least 2-3 hours. Follow the standard process of cleaning off the residue. Pay particular attention to cleaning the residue and neutralizing the surface with ammonia.
10. Allow the surface to dry for at least 24 hours, before sealing it with one coat of water based epoxy, Perdüre E32 and one coat of water based polyurethane, Perdüre U46.

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Elevator Lobby - Before

Elevator Lobby – After

 A wood floor or a plywood subfloor can be converted into a beautiful concrete floor using self leveling concrete, Param 5500. Recently, Mirage Studios of Valley Stream, NY resurfaced an existing wood floor with self leveling concrete on 19th floor of a building on 3rd Avenue in NYC. It took 5 days to complete the whole process. The first three days were full working days where as the last two days were partial working days because of the sealer application process. One coat of water based, low VOC- epoxy primer/sealer, Perdure E32 was applied and two coats of water based, low VOC-polyuretahne top coat, Perdure U45 was applied to give better abrasion resistance.

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Concrete Resurfacing over Gypcrete

Acid Stained and Sealed Lobby Area

Few months ago Gary Jones and I were in Cleveland, OH to consult on a decorative concrete project. The contractor was fairly new in the business and the area was large (4500ft²) for him to handle by himself. Therefore we were invited to consult on the project.

The project entailed –

Acid Stain and seal lobby areas – 3500ft²

Resurface and Acid Stain two rest rooms – 1000ft²

Time allotted – 4 days (Start Thursday morning and finish it by Monday morning)

Project crew – 5

We had planned in such a way that it was all doable in 4 days and nights. As we all know there are always surprises on every project. When we inspected the project site on Wednesday evening, we got a big surprise. The concrete surface that was to be acid stained in the lobby area was NOT concrete…it was gypcrete! This contractor who was new in the decorative concrete business did not realize that the gyprcrete and Concrete are different and gypcrete cannot be acid stained. (I guess you understand now, why I am not mentioning the name of the contractor).

Since walking away from the project was not an option, we decided to resurface gypcrete with a micro-topping (Sgraffino Superfine, SF). There were two big challenges with resurfacing –

1. Additional cost of resurfacing 3500ft²
2. Time restriction

The availability of Sgraffino SF was not an issue because the products were available in the company warehouse that was located in Cleveland, OH.

To minimize the additional cost of resurfacing, to speed up the application process and to give a smooth surface, we decided to spray the Sgraffino SF. By spraying Sgraffino SF we were able to

1. minimize the cost of additional products required (because spraying increases the coverage rate by at least 1.5 times)
2. resurface 3500ft² in 3.0 hours (1 coat) and
3. achieve a very smooth surface (without any trowel marks)

Needless to say the project was completed in allotted time period and as you can see from the pictures the floor looks great. For an additional cost of $0.48/ft², the contractor was able to give their customer what he promised and still make good money.

Please let me know if you are interested in information like – step by step process (with time periods for each step), acid stains and sealers used, etc. I did not want to bore the readers with this trivia.

Lesson learned from this experience: Concrete resurfacing is the best way to acid stain Gypcrete and one can get great results by spraying the micro-topping. Please note spraying is a good option for large areas and when you already have a smooth (level) surface. Since this floor was very smooth (gypcrete installer did a good job), one coat of Sgraffino SF was sufficient.

More and more contractors are adopting this process on self leveling concrete. Most of the self leveling concrete products (those I know), do not give good results when acid stained. Of course they look very good when dyed and sealed. Moreover self leveling concrete surfaces look plastic (for lack of any other words). The best solution is to spray Sgraffino Superfine. Recently, Hudson Concrete Contractors in NYC used this process (self leveling concrete plus spray) for 18,000ft² in Martha Stewart’s corporate office in New York City.  The floor preparation and self leveling this area took almost a week but spraying the whole area was done in ONE DAY!

I know you want to see the pics…unfortunately we are not allowed to take the pics (if you are in the NYC and want to take a look at the floor, please contact me). The floor has typical New York look…different shades of grey.

Food for thought…how about sprucing up stamped concrete with this process! Please feel free to contact me if you would like to discuss this further.

Wish you all a very Happy New Year!

Thank you

Victor Pachadé

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Application of Sgraffino

Acid staining concrete is a process in which an aqueous solution of metallic oxides and inorganic acid is sprayed over an existing concrete surface. This acidic solution of metallic oxide reacts with lime (Calcium Hydroxide) present in the concrete yielding insoluble, colored compounds that become a permanent part of the concrete. Therefore, one of the basic conditions where coloring concrete using acid stains is going to work is the presence of lime in the concrete. Quiet often people who have just bought a home or condo, remove the carpeting or vinyl tile, and find something underneath which they believe is concrete. When they spray the acid stain or reactive stain and wait to get disappointed because they do not get desired results. This is because the substrate that looks like concrete is in fact gypsum based ‘Gypcrete’. Builders often use this on upper floors to level out areas of sub flooring and provide a good base for other types of floor coverings. Unfortunately, staining Gypcrete does not produce any desirable results since it does not contain any lime; moreover it is too soft and easily abraded. Therefore ‘Gypcrete’ cannot be used as a wear layer.

Since Gypcrete surfaces cannot be used as a wear layer and acid stains do not work on them, it is usual practice to apply a 1/16inch polymer modified concrete resurfacing material (also called micro-topping or skim coat). One of the key things to remember here is the bonding of micro-topping or concrete overlay to Gypcrete (or gypsum based underlayments). This mirco-topping not only should bond to the substrate but it should be able to produce beautiful acid stain colors. Please find below the steps involved in resurfacing Gypcrete and acid staining with a micro-topping or skim coat –

1. Sweep the Gypcrete surface and dry vacuum the surface thoroughly. Rake out the joints where drywall meets the floor. Clean the adjoining areas even those not being resurfaced with a micro-topping.
2. Install masking paper (plastic) at least 48” high on the surrounding walls. Spray a light mist of water just to damp the surface (DO NOT FLOOD!)
3. Using a brand new rayon mop, apply the first coat of acrylic primer (Cp1000) after diluting it with water @ 1:1 ratio. After waiting for at least 60 minutes, apply second coat of diluted acrylic primer and let it cure overnight (or 10 hours at least) before proceeding to the next step.
4. Apply another coat of acrylic primer, this time non-diluted and let it dry for 30-60 minutes. The third coat of primer can be applied using a sprayer (SP Systems or Chapin).
5. Apply a thin coat (1/16”) coat of micro-topping or polymer modified overlay using magic trowel. Please follow the link for specific instruction on application of polymer modified micro-topping, Sgraffino. Allow the micro-topping to cure for at least 24 hours. In damp and cold conditions (basements), wait for at least 48 hours before proceeding to the next step.
6. Apply the acid stain on the completely cured micro-topping. Please follow the link for specific instruction on application of the acid stain, Patinaetch. Allow the acid stained surface to dry for at least 24 hours before proceeding to the next step.
7. The micro-topping needs to be protected with a good quality sealer. Apply one coat of water based epoxy sealer, Perdüre E32 followed be another coat of water based polyurethane, Perdüre U46. Allow at least 6 hours between the application of epoxy primer and polyurethane.

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Moisture-induced problems with flooring materials installed on concrete slabs on ground continue to plague the construction industry. This results in wasted materials, frayed relationships, voided warranties, lawsuits and loss of faith in the contractor working on the project. Please find below the list of options available, when a moisture vapor emission is detected in a concrete slab.

Option 1 – Do not install the floor

The Floor Covering industry at large specifies a maximum vapor transmission of 3.0 pounds over 1,000 square feet in 24 hours for resilient products, and a 5.0 pound maximum transmission for breathable carpeting systems. Emission levels higher than the specified maximum tolerance will result in eventual failure. If the slab vapor transmission distribution exceeds the maximum tolerance for a flooring material then the first option is to simply not to install a floor surface.

Option 2 – Remove & Replace the Concrete

If the slab vapor transmission distribution demonstrates high volume under normal environmental conditions, it is due to the porosity of the concrete. The slab has a permanent condition, and unless treated to correct the problem, then the only way to eliminate it is to replace the slab.

Option 3 – Install a raised access floor system

If the slab vapor transmission distribution is too high for flooring, then a raised floor system can be installed that does not allow the direct contact of flooring to substrate. However, a raised floor system can be installed that does not allow the direct contact of flooring to substrate. However, a raised floor system does not deter the vapor emission from occurring, and can result in water condensing under the floor. This environmental creates a theater for biological growth.

Option 4 – Let the flooring fail

Unfortunately, this is the number one practice. The reasons why people would ignore the data that demonstrates a potential for failure, are many. Sometimes it’s the disbelief that a problem exists. Sometimes it’s the fact that there is no money in the budget to address unexpected problems. Many more times it’s because there was no testing or of tests were performed, the importance of the result was written off as no big deal. The sign off is the worst of these.

This occurs when the flooring contractor has told the owner that their concrete substrate is not in condition for installation. This is not the fault of the flooring contractor who is being conscientious enough to warn the owner of a potential problem. If the owner refuses to correct the condition, the flooring contractor is left with two choices: Refuse to install the material and fight a breach of contract suit, or request the owner of the project sign off the liability for future failure. Either way, it’s a tragic issue.

Option 5 – Correct the problem

If the slab vapor emission distribution is too high for adhered flooring, the substrate in place can be brought into compliance for installation of any type of flooring product or coating. This can be done successfully for a fraction of the cost of replacing the slab or otherwise experiencing an inevitable floor system failure.

It is a well known fact that the time, energy and quality resources you put into your property will be reflected in its value. Protecting that investment begins by choosing the proper installation materials such as Perdüre MVT – moisture vapor treatment before the installation of any kind of floor covering. It is a two component epoxy system, minimal odor; low per square foot cost reduces moisture vapor readings ranging from 8-10lbs. It is designed as a negative side moisture vapor retarder to reduce moisture vapor emission through concrete slabs.

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Polyurethanes are produced by the reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives. Isocyanates can be classed as aromatic or aliphatic. Depending upon the type of isocyanate used in the reaction, there can be either aromatic polyurethanes or aliphatic polyurethanes.

Polyaspartic is an aliphatic Polyurea.
So what is Polyurea?

Polyureas are produced by the reaction of a polyisocyanate with an amine terminated polyester resin. The result of the reaction between aliphatic polyisocyanate with a diamine is called Polyaspartic Polyurea or in shot Polyaspartic.

The terminology sounds verbose and pedagogic but it is very important to understand these terms for anyone who is in the coatings industry so that they can speak knowledgeably with their clients.

Polyaspartic sealers are different in both application and performance properties from Polyurea. Polyaspartics are similar in application and performance characteristics to aliphatic Polyurethane sealers.

Difference between Polyaspartic and Polyurethane Sealers/Coatings

It is also important to understand the difference between Polyaspartic and Polyurethane sealers / coatings because one can be substitute for the other.

Why would you want to do that?

Polyurethane sealers are less expensive than Polyaspartic and they perform (abrasion, chemical and UV resistance) similarly after they have been fully cured. Therefore if the project conditions allow one can be substituted for the other.

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Polymers have been used as additives in cement mortars and concrete since the 1920s when natural rubber latex was added to road paving materials. Since then there has been considerable development of polymer modification for cement and concrete. Polymer modification of cement mortar and concrete noticeably improves application and performance characteristics. These property advancements include easier handling, better finishing, higher strength and adhesion, and increased durability.

Mechanishm of  Action

The properties of polymer modified concrete depend significantly on the type of polymer utilized and the polymer-to-cement ratio, which is defined as the mass ratio of the amount of polymer solids to the amount of cement. The polymer-to-cement ratio can vary from 0 to 1/3 depending on the type of polymer used in the properties required for the application.

There are two theroies for why the properties of concrete are impoved ith the addition of polymers. In the first tehorey, there is no chemical interaction between the polymer and the cement. During the hydration of the cement, the hydrophillic part of the polymer is oriented toward the water pahse, whereas the hydrophobic part is directed toward the air phase (pores and capillaries that are not filled with water). On drying, the water is removed and the hydrophobic particles coalesce together and forma film.

The second theorey is that the polymer interacts with the components of the Portland cement hydration products and forms new complexes. This creates a type of reinforcement in the concrete and produces semipermeable membranes. Chemical reactions have been noticed to take place between the particle surface of reactive polymers such as polyacrylic esters and calcium ions in the hydrating cement. Such reactions can improve the bond between the cement hydrates and aggregates and improve the final properties of the modified cement.

In actual practice both theories are likely to be applicable depending on the typer and chemistry of the polymeric ingredients and the conditions present during hydration of the cement. The situation is highly complex since some low molecular weight chemicals (e.g., amine accelerators) that are present in the commercial polymer admixtures can also influence the reaction of Portland cement with water.

It is very important that both cement hydration and polymer film formation proceed well to yield a monolthic matrix in which the cement phase and the polymer film formation proceed well to yield a monolithic matrix in which the cement phase and polymer phase interpenetrate. The cement hdyration process generally will occur faster than the polymer film forming process. Aggregates are then bound by this matrix.

The properties of both fresh and hardened cement are affected by parameters such as polymer type, polymer-to-cement ratio, air content and environmental conditions during the hardening of the mixture. Superior physical properties result compared with conventional unmodified cement mixtures. It is possible that the polymer films in cement act as crack-stoppers for any microcracks that can develop under stress. This will also lead to increased tensile strength and fracture toughness. Such effects as improved tensile strength, fracture toughness and waterproofness generally increase with increasing polymer-to-cement rations up to certain limits.

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Before concrete resurfacing

After resurfacing and sealing

Concrete floors have become new floor covering choice for designers and home owners across Unites States and Canada due to their artistic designs and durability. During renovation and remodeling of existing buildings, quiet often it is required to convert an existing floor covering like vinyl tiles or carpets into concrete flooring. If the existing floor covering in a bad shape, it must be removed before installing new flooring. Asphalt-based cutback adhesive remaining on a concrete floor after removing old vinyl tile and other flooring represents one of the most difficult and risky subfloors for the installation of new flooring. The removal of cutback using grinding, sanding or blasting may contain asbestos. This poses serious health concern.

 The use of solvents based adhesive removers is precluded due to the smell of the solvents in occupied buildings. Quiet often they are not VOC compliant and this greatly affects the LEED points.

 The following steps are recommended for resurfacing cutback adhesives and carpet glues with a self leveling concrete, Päram 5500:

1. Before installing the self leveling concrete, the installation contractor should ensure that the subfloor is properly prepared.
2. Thick accumulations, powdery, brittle or otherwise weak adhesive layers must be removed. Use the wet-scraping method to remove the thick areas and build-ups of adhesive, and any areas that are weak and not well bonded to the substrate.
3. The hollow spots or non-structural cracks in the floor should be addressed before proceeding further.
4. The substrate temperature should be a minimum 45⁰F during application and air temperature maintained between 50-80⁰F. Adequate ventilation should be provided to ensure uniform drying.
5. The surface is primed with Param Süper Primer. It should be distributed evenly over the floor surface and then brushed into the substrate with a soft bristled push broom. Avoid pudding of primer. When applying with a pump sprayer, make sure to cover the substrate with an even coat to ensure proper penetration and follow immediately behind to work into the surface with a push broom. Drying time is 2 to 4 hours depending upon climate conditions.
6. The substrate is ready to accept self leveling concrete after the primer is completely dry. Please follow the link for instructions on installing self leveling concrete. http://www.duraamen.com/products_sl_concrete.php 
7. The surface of Param 5500 must always be protected from oil, salt, water and surface wear by applying a suitable sealing system. A very popular system is application of water based epoxy primer/sealer, Perdure E32 and then applying a coat of water based polyurethane, Perdure U46 (gloss) or Perdure U45 (matte).

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