What’s the Difference Between Flowing Concrete and Liquid Floor Screed?

liquid floor screedIf you’re a contractor, builder or DIYer, chances are you’ve heard “liquid floor screed” and “flowing concrete” used interchangeably.

It can be enough to drive any well-informed professional or enthusiast mad.

If you don’t quite know the difference between the two, don’t worry: many don’t. However, comprehending the basic discrepancies is a quick way to show you know your stuff at the next business meeting. It also can help with clarification purposes when discussing projects.

So what are the differences? It’s time to find out.

The Basics

Screeding is, quite simply, adding a top layer of material that is applied over concrete subfloors. It provides a level surface for the good stuff: the floor finish.

Screeding increases the life of a floor and keeps everything level.

Throughout the UK, floor screed is a popular choice for houses and businesses because of its ease of application and reliability. In Germany and Europe, approximately 80% of floors have dried liquid screed.

What Is Liquid Floor Screed?

Liquid screed, sometimes referred to as “self-leveling screed,” is a mortar primarily made of cementitious materials and sand.

There are several basic kinds, including unbonded, bonded, floating and heated screed flooring.

The Screed Scientist(R) writes, “When a well-laid screed can extend the life of a floor and do wonders to its quality, a failed screed can drastically affect the quality of the floor and could be an immensely expensive issue with drastic measures being essential to revive it to an acceptable condition.”

A screed is an essential component of a successful and strong floor.

What Is Flowing Concrete?

Aggregate, stones, cement and sand make up flowing concrete. In this liquid form, the slump is temporarily higher than normal.

Typically, adding admixture once the concrete arrives at a job site results in flowing concrete. Its use varies, from foundation building to flooring. It is an inexpensive material that has few maintenance requirements.

Although many think the added water and other materials may make flowing concrete weaker, some reports indicate it is actually stronger than normal concrete.

What Are the Similarities?

Surprisingly, the two share only a couple of similarities.

Composition

The terms are used interchangeably because liquid floor screed and flowing concrete are made of virtually the same ingredients: cement, water and aggregates. However, the ratio of each varies depending on the type of material.

Consequently, they look very similar once cured.

Recycling

Almost 40% of calcium sulfate screeds is recycled gypsum. Instead of going to a landfill, it is used in liquid screed. Additionally, this form of screed can be 100% recycled after a building reaches the end of its life.

Concrete can also be recycled. In fact, over 140 million tons are recycled each year. Recycled concrete makes road base, soil stabilization, pipe bedding and landscape materials.

However, the similarities end there.

What Are the Differences?

Although they are made of the same material, flowing concrete and liquid screed are two very different beasts.

Drying

Concrete can take much longer to dry than a screed. Oftentimes, it can take up to a week, although light traffic may walk across the concrete within a day to three days. The general rule of thumb is that drying takes about 28 days per inch, but this period is highly variable depending on thickness, weather, and other factors.

Additionally, concrete cannot be force dried; limiting the amount of water in the concrete is one of the few ways to encourage it to dry faster.

Comparatively, some liquid screed can be walked on within 24 to 48 hours. The full drying time can be as few as 14 days or as high as 21 days.

Additionally, forced drying can be used to speed up the process. However, only professionals should attempt this. If overdone, forced drying can cause cracking and curling.

Use

Unlike concrete, liquid screed is made for finishing. Concrete is not.

As a result, concrete tends to be stronger. This is why it is used in a diverse manner compared to screed.

It’s also why concrete is used in almost everything except finishing. It makes up entire structures and is utilized in construction and driveways and sidewalks, whereas screed is a finishing material placed on top of a concrete base.

Appearance

To the untrained eye, concrete and screed will look the same. However, upon closer inspection, viewers will notice one is rougher.

Because concrete is comprised of many stones, it has a coarse look and feel to it. Because sand is used more in its creation, liquid screed is smoother.

Underfloor Heating

Much of screed’s popularity has resulted from its usefulness in underfloor heating. Its smooth, liquid form allows the mixture to reach around pipes and other obstructions.

When laid, floor screed is thinner. Combined with its ability to spread around all cracks and crevices, this results in more efficient heating. Unlike with thick concrete, heat can transfer quickly and easily to the floor of the building.

Application

Application of concrete requires floats or piston pumps due to its wetter nature. Screed installation requires using pneumatic pumps, forced-action mixers or (in some cases) grout or worm pumps.

Because of the differences in installation and consistency, liquid screed is laid much faster than concrete. In fact, pumping 2,000 square meters in a day is not out of the question.

Carbon Dioxide Production

Liquid screed does not require any burning during its manufacturing. As a result, its use decreases industries’ carbon footprints compared to concrete.

Concrete requires significant heating when made. America’s Portland Cement Association found that 927 kilograms of carbon dioxide are emitted for every 1,000 kilograms of Portland cement produced in the country.

Concrete Service

See the differences? Both flowing concrete and liquid floor screed have their own uses and benefits, but they are not the same substances.

So next time you hear your coworker use one of the terms improperly, gently correct him and spread the word.

Or you could ask Gyvtek to give you a hand. Our company is in the business of installing liquid screed, and our specialists are the best in the field. Contact us today to get a free quote for your building.

Concrete service on liquid screed. It doesn’t get much better than that.

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