Mechanically Polished:

Not all concrete floors are ideal for polishing, in fact a high percentage of existing concrete surfaces will not produce the strength and high sheen exposed aggregate finish that the home or business owner envisioned or expected. Unfortunately most homeowners see a floor with a high gloss sealer on a ground concrete substrate and assume that this is polished concrete. However this is not the case and more often the application they are viewing is a “grind and seal”.

 

Polished concrete is not sealed. These floors are brought up to the higher grit levels and have been chemically hardened (densified). Polished concrete without the densification step will be much more susceptible to staining, dusting and abrasion. They will provide a high gloss finish that is relatively stain resistant for a surface without any form of sealer. Polished concrete floors are not stain proof as so many people are led to believe and even with a stain guard added, a floor may still stain. A stain guard will usually only give added time for the clean up….

 

In general, a mechanically polished floor is ground to the level of exposure required by the client, grouted then densified. After using the metal bond diamonds to grind the substrate it will be polished to the finish required using resin pads. The process generally takes some time, as there are many steps involved.

 

Grind and seal:

Is exactly as the name implies. The concrete substrate is ground back generally up to the 200 grit level and then coated with a topical concrete coating/ sealer. These coatings can either be acrylic, epoxy or polyurethane.

 

There are some benefits to a grind and seal over polished concrete:

 

o   Less labor intensive

o   Depending on the sealer used they may offer higher abrasion resistance.

o   Cheaper per m2

 
New concrete is to be at 32 mpa and will need to be laid by a concreter ensuring it is flat with no screed marks or footprints. The mix and method laid is critical for a quality finish and will keep your costs down when grinding. Any additional grinds will cost you more….

 

If you’re thinking of having a new or existing floor polished or grind and sealed then do your homework.

It doesn’t hurt to quiz your contractor. Ask them about their process and what products they use. Especially for a grind and seal. Not all sealers are created equally and some may deteriorate faster or yellow over time…

Selling a polished flooring system and delivering a grind and seal is a common occurrence. Selling a polished concrete floor and not offering the advantage of the densification process while still charging top dollar is also a common occurrence.

So do your homework and quiz, quiz, quiz…….


Grrr ind

 

 

  Hard to believe that cement and concrete has been around for over 5,000 years. From way back to the days of the Egyptians using it to build the Pyramids to today with the beauty we have created with it. Concrete has been used for many amazing things throughout history, including architecture, infrastructure and more. Below is a timeline throughout history with the changes and uses it’s made to the introduction of “Polished Concrete”…

3000 BC - Egyptian Pyramids

The Egyptians mixed mud and straw to form bricks and used gypsum and lime to make mortars. These were early forms of concrete and were used to build the Pyramids.

3000 BC – Egyptians used cementious materials to hold bamboo together in their boats and in the Great Wall.

300 BC - 476 AD-Roman Architecture

The ancient Romans used a material that is remarkably close to modern cement to build many of their architectural marvels, such as the Colosseum, and the Pantheon. The Romans also used animal products in their cement as an early form of admixtures.

1779 – Bry Higgins was issued a patent for hydraulic cement (stucco) for exterior plastering use.

1824 - Portland Cement Invented

Joseph Aspdin, bricklayer and mason in Leeds UK, is credited with the invention of Portland cement. He named his cement Portland, after it resembled the stone quarried on the Isle of Portland off the British coast.

1836 - Strength Testing

 The first test of tensile and compressive strength took place in Germany. Tensile strength refers to concrete's ability to resist tension, or pulling apart forces. Compressive strength refers to concrete's ability to resist compression, or pushing together forces. Both tensile and compressive strength are expressed in pounds per square inch (psi).

  1868 – The first shipment of Portland cement is sent to the United States.

  1889 - Alvord Lake Bridge

  Alvord Lake Bridge was built in 1889 in San Francisco. This bridge was the first reinforced concrete bridge, and it still exists today, over 125 years after it was built!

1891- Concrete Street

In 1891, the first concrete street in America was built in Bellefontaine, Ohio. Today pervious concrete is being advocated as the best, and most environmentally friendly, surface for streets.

 
1903 - The Ingalls Building

  The first concrete high rise was built in Cincinnati, Ohio, in 1903. The Ingalls Building, as it is called, has sixteen stories, making it one of the great engineering feats of its time.

1908 - Concrete Homes

  In 1908, Thomas Edison designed and built the first concrete homes in Union, New Jersey. These homes still exist today. Edison envisioned that his design would meet great success, and that before no time everyone in America would be living in a concrete home. However, his vision did not become a reality as soon as he expected; in fact, concrete homes are just starting to gain popularity now, one hundred years later.

1913 - Ready Mix

  The first load of ready mix was delivered in Baltimore, Maryland in 1913. The idea that concrete could be mixed at a central plant, then delivered by truck to the job site for placement. This revolutionised the concrete industry.

1915 - Colored Concrete

  Lynn Mason Scofield founded L.M. Scofield, the first company to produce color for concrete. Their products included color hardeners, color wax, integral color, sealers, and chemical stains.

1930 - Air Entraining Agents

In 1930, air-entraining agents were used for the first time in concrete to resist against damage from freezing and thawing.

 
1936 - Hoover Dam

The Hoover Dam, completed in 1936, is located on the Colorado River, bordering Arizona and Nevada. Up to this time, the dam was the largest scale concrete project ever completed.

 
1938 - Concrete Overlay

John Crossfield was the first to receive a patent for a concrete overlay. He added latex to Portland cement, aggregate, and other materials to make a covering for ship decks. Today, concrete overlays are made by blending polymer resins with cement, and widely used for their decorative appeal.  

1950's - Decorative Concrete Developed

Brad Bowman developed the Bomanite process, the original cast-in-place, colored, textured and imprinted architectural concrete paving, in the middle 1950's in Monterey, California.

1970's - Fiber Reinforcement

Fiber reinforcement was introduced as a way to strengthen concrete. Today glass fibre reinforced concrete is now becoming widely used in replace of aggregate for use in countertops and furniture. Mainly due to it being lighter than concrete with aggregate and the curing time being shortened.

 
1980's - Concrete Countertops

 Buddy Rhodes, the father of the concrete countertop, cast his first countertop in the mid '80s. Around the same time, Fu-Tung Cheng also cast his first concrete countertop. In the 35 years since, concrete countertops have become incredibly popular due to their durability, beauty and range of customization.

 
1999 - Polished Concrete

HTC, originally a Swedish company, introduced concrete polishing to the United States. The first installation in the US was a 40,000-square-foot warehouse floor for the Bellagio in Las Vegas.

 

 Today, the popularity of polished concrete has soared with it being used in retail stores, homes, outdoor areas and even as furniture. Not only polishing its natural state, but adding materials to its mix to grind and expose its inner beauty…

Concrete has been around a very, very long time and is being used in many applications. I wonder what it will be used for in the next 100 or 1000 years?

 
Grrr ind…..