A Brief Overview of the Dangers of Reinforced Concrete

Concrete was by itself durable enough for construction until the 19th century when innovation led to the development of steel reinforcement. From then on, it didn’t take long for its popularity to spread.

Engineers saw reinforcing concrete as a way of reducing construction cost and saving time while bringing to life even stronger, more durable structures. Today, reinforced concrete has seen the rise of some of the world’s tallest skyscrapers, biggest bridges, longest highways and deepest tunnels.

While these mega-structures have lived up to the expectation the inventors of reinforced concrete had regarding strength, durability has been a different situation altogether. But before we delve into that, let us first discuss what reinforced concrete entails.

reinforced concrete
© ArchiExpo

What Is Reinforced Concrete?

Reinforced concrete is a composite material made by casing wet concrete around steel reinforcing bars tied together to make a cage.  The concrete settles and hardens around the bars.

At this point, you’d be glad to know any reasons behind concrete reinforcing.

To start with, concrete is known to have relatively low tensile strength and ductility.  

Reinforcing it counteracts both weaknesses resulting in a new material that works well in either tension or compression. The concrete resists squeezing while the steel resists bending and stretching.

 

Why Steel?

In theory, all kinds of metals can be used to reinforce concrete. However, steel is the most preferred because it expands and contracts almost the same way concrete does.  

This similarity in thermal expansion characteristics ensures the steel bars doesn’t crack the concrete that surrounds it.

Alternative materials for concrete reinforcement exist such as aluminium bronze, glass, and plastics. However, the affordability of plain steel makes it a lot more attractive to developers.

Reinforcing concrete is favoured among builders for numerous reasons. For starters, steel bars give strong building structures with thinner, less supported slabs. Such slabs require less concrete to pour making the construction process go faster.

 

Strength versus Durability

silent crushing reinforced concrete slab
© dynacem

Many planners and developers, however, fail to consider the extended costs of maintenance and repair services of reinforced concrete construction. While blending steel with concrete improves the structure’s daily tolerance with tension, it reduces its durability in the long run.

How does this happen you ask? Let us elaborate.

Modern concrete structures fail through what is informally known as concrete cancer.  This destructive process involves the following three problems, all of which are interrelated.

 

1. Natural Deterioration

 

Concrete is a combination of three ingredients:

– A mixture of fine and coarse fragments of crushed rock, such as sand, gravel and stones, glass etc.;

– Cement; and

– Water

Over time, concrete decomposes naturally as a result of a slow but steady reaction between alkalis from the cement and silica from the fragments.

The crystals formed from this reaction occupy and spread spaces within the structure.  Eventually, we have cracks from the inside, or flaking from the surface. Through, either way, moisture finds its way into the structure and corrodes it.

 

2. Cold Temperatures

 

Water that has seeped into concrete through cracks can freeze in the winter. It will then expand causing further cracks and faults within the structure. More water can get in through these new entry points, making the vicious cycle of deterioration and decay continues.

 

3. Steel Rusting

 

Despite the inevitable natural deterioration of concrete and harsh environmental conditions, old structures such as the Colosseum and the Pantheon in Rome are proof of just how long concrete can last.

It is puzzling that many concrete structures erected in the 20th century have no more than a few decades of life to show for themselves.

Structures built with reinforced concrete experience a significantly accelerated rate of degradation due to rust. This is because moisture that enters through small, newly formed cracks can eventually come into contact with the reinforcing bars in the concrete, causing them to decay.

The rust that forms around the bars results in their rapid, uneven expansion. Rust can expand the reinforcing bars up to four times their size. This enlarges existing cracks and creates new ones, finally forcing the concrete to fall apart.

 

What are the Dangers of Reinforced Concrete?

danger do not enter sign

By facilitating concrete cancer, construction with reinforced concrete poses a danger to the structure and the people using it.

Many of us wouldn’t expect to find cracks in a newly made, modern building or bridge. When such structures fall apart, it is very likely to take its unsuspecting occupants down with it.

Yet, the casualties left in the wake of reinforced concrete construction do not end there. Growing concerns about the environment and climate change have shed light on another major problem.

Concrete production is the third largest contributor of carbon dioxide emissions after automobiles and coal-fuelled power plants. In fact, cement manufacturing alone is responsible for about 5% of carbon dioxide emissions in the world.

Moreover, concrete waste represents roughly a third of all landfill waste, both an outcome largely attributed to the construction of short-lived structures.

Because recycling concrete is impractical, the only way to save our planet from its effects is to reduce its production. This will only be possible if we start building longer-lasting structures.

 

Potential Solutions

Fortunately, you can address the problem of steel corrosion in reinforced concrete in many ways including;

1. Pre-stressing/pre-tensioning: The reinforced steel is permanently compressed by first applying tension on the steel bars. As the concrete sets, the taught bars pull inwards, compressing the concrete and making it stronger.

2. Cathodic protection: The entire structure is connected to an electric current which prevents rust from forming around the steel bars.

3. Chemical treatment: The concrete is treated with a rust-inhibiting compound. A common mechanism of inhibiting corrosion with chemical treatment involves the formation of a coating onto the steel. This prevents moisture from reaching it.

While builders are widely applying the methods above to deal with degradation, nothing can fully mask the fact that reinforcing concrete with steel greatly reduces its durability.

Avoid the dangers and hire professional, hire MEGASAW call us at 1300 920 419.

How to Level a Concrete Floor

How To Level Concrete Floor High Spots

Many people consider concrete as the best flooring material, given its versatility. It perfectly suits both classic and modern décor for both home and commercial use.

When polished, a concrete floor can be the most beautiful element in interior spaces. The flooring can also last longer than just about any other contemporary flooring material.

But on the flip side, a concrete floor, particularly one that’s not polished can develop problems over time. The floor can settle unevenly, creating a visible dip on the surface. Moreover, it has tendency to develop cracks that can range from shallow and insignificant to deep and dangerous.

READ: Warning Signs Concrete Cutting and Repairs are Needed

These cracks can widen to the point that they may trip you when walking on the floor. Moisture can also seep in, damaging the floor over time.

Basements are most vulnerable to these, considering the heat and cooling that happens there.

When you see little cracks, these should be repaired to keep everyone safe and restore the floor’s beauty. This also helps increase the value of the property. If in repairing the floor, you’re considering to plan to put tiles or hardwood, you’ll need a levelled surface to work on.

But before you do the repairs yourself, note that it’s best to enlist professional help in repairing concrete floors. With this, you would avoid common problems associated with concrete floors such as high spots and unevenness.

Leveling Concrete Using Grinding

For an uneven floor, grinding the concrete floor high spots is your only option.

Although this sounds simple, this requires a great level of skill and equipment. These are in addition to the physical requirement in carrying hefty bags of compound and equipment.

This is where tapping professionals come in handy.  At the onset, they can identify where the high spots are, by using varying methods. For one, some concrete grinding service people put water on the floor to find the high spots.

(c) Wikihow

Besides finding the high spots, the major challenge is in knowing when to stop grinding. Problem is there are no means to accurately determine when the desired levelling has been achieved.

Using a heavy-duty grinder

The kind of tool you use in grinding concrete floor high spots determines the quality of your concrete repair.

A walk-behind heavy-duty grinder with diamond blades on the bottom gives great results. But be careful. The blades in this machine cut so rapidly that a small miscalculation may result in a major dent on the surface.

You’ll need to mount a laser receiver on the grinder to signal that it is time to stop grinding.

In using the receiver, first put the grinding machine on a section of the that has the right elevation.  Then adjust the transmitter elevation until the receiver gives an on-grade indication.

After that, your crew can move to each high spot.

Terrazzo machine

Besides the grinder, some concrete grinding crews prefer a terrazzo machine with Carborundum stones. But this is slower than the diamond grinders.

This machine is typically used by concrete grinding professionals. If you opt to do the grinding yourself, it’s best to lease than buy one.

Problem is, you won’t have the level of expertise to deliver a spot-on result. That’s why unless it’s best to leave all concrete grinding work to experts such as Megasaw that have been doing it for well over 20 years.

© blastrac.fr

Dust free grinding – most recommended

Besides aiming for the best result for your floor, you should also be concerned about the dust that comes from grinding.

This dust should not to be toyed with. Exposure to the cement dust can irritate eyes, throat, nose and the rest of the respiratory system. Moreover, if it comes into contact with the skin, it may cause moderate irritation,  cracking or thickening of skin.

Worse, the concrete dust may severely burn the skin. It can also damage the lungs, cause lung cancer and silicosis.

To ensure that there’s no dust, you need a concrete grinding equipment fitted with state of the art dust shrouds. These vacuum all the dust as the grinding work is in progress.

Get the company with most experience

To get the best out of your concrete floor grinding project, always go for the company with the most experience.

With over 20 years of concrete grinding in Melbourne, Megasaw has the experience, equipment and expertise to grind high spots in your concrete spots grand deliver the results you want.

In addition, you’ll be delighted to know that the company’s technicians take additional precautions to protect you and the rest of your property from cement dust.

Contact us today to get a quote.

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CONCRETE GRINDING SOLUTIONS

CONTACT US today or CALL 1300 920 419

What is Concrete Resurfacing

Concrete is an extremely strong and durable material. That’s why it is ideal for the following spaces in indoor floors, garages, driveways, patios, pool decks and among many others.

concrete resurfacing

But no matter how durable concrete is, foot traffic and harsh elements can wear it out over time. Fortunately these days, concrete floors that are not in top shape can be restored.

 

What is Concrete Resurfacing?

Concrete surfaces can be damaged and have discolourations in the long run. Traditionally, to repair damaged areas, worn out concrete must be removed and replaced. But recently we have seen that it’s easier and more cost-effective to restore concrete surfaces.

Concrete resurfacing renews mildly worn out or slightly damaged concrete surfaces, without needing to remove or replace the existing concrete.  The old concrete structure is used as the base for the resurfacing material.

concrete resurfacing

Concrete Resurfacing VS Traditional Method

Compared to the traditional method, concrete resurfacing is:

– cost efficient

– less tiring

– time consuming

This is because there is no need to replace the broken concrete. The concrete resurfacing material is made of special bonding agents and a thin cement-based overlay that are combined together to form a mixture.

This mixture is then poured on top of the existing concrete to form smooth and renewed surfaces. It would take around 24-72 hours for this concrete resurfacing material to dry up and ready for you to step or drive on. When it dries, your concrete floor becomes more durable and stronger.

 

How To Concrete Resurfacing

Any handy homeowner can do concrete resurfacing provided they have all the necessary equipment. It takes cleaning, repairing and overlaying a new concrete material.

 

Step 1: Clean the entire aging surface.

This is crucial. Take out any debris and loose concrete completely. You can use a power washer to make sure will help you remove all the remaining fragments.

Most manufacturers of concrete refurbishing material recommend cleaning with a 3,500 psi washer. To remove tree or paint sap and oil stains,  use a sealer.

concrete resurfacing
Image credit to Concrete Repairman

Note that when using cleaning agents or chemicals, you must thoroughly wash the surface to remove  the chemicals.

This is necessary because any residue can interfere with how the concrete resurfacing material adheres to the old concrete surface. Also, make sure that the adjoining house walls and the surroundings of the treated area are covered to protect against over spraying.

 

Step 2: Repair the concrete.

Fill cracks, holes and dents properly to have a smooth canvas for the new concrete material. Reinforce cracks with fabric and then cover them with a polymer concrete. Be sure to smooth it out evenly with the surrounding concrete. On the other hand, fill holes with epoxy mortar. After this, you can apply the first coating.

concrete resurfacing mixture
Image Credit to Today’s Home Owner

Step 3: Mix the concrete resurfacing material one bag at a time.

A 40-pound bag usually needs 3½ quarts of water. If you are mixing in warm temperature, use cold water, while use warm water in cool temperatures. For best results, mix the substances using a ½ inch drill and paddle mixer.

Here’s how you create a mixture. In a clean plastic bucket, pour the water and mix in the 40-pound bag resurfacer. Mix for several minutes until it becomes smooth and has a pourable consistency. Let the mixture rest for a few minutes and then mix again.  Add a little more resurfacer or water if needed. Doing this creates a pourable mixture.

concrete resurfacing
Image Credit to Multi Coat

Step 4: Overlaying.

Once your concrete surface is cleaned, repaired, and moistened, it is now ready for overlaying. But before laying out resurfacing material you must spray the surface with the hose. This is done to prevent the concrete won’t draw the moisture out of the resurfacing material.

Be sure to remove all the water off the concrete surface. Then, pour a little amount of the mixture on the surface. Spread the resurfacing material evenly to create an even and smooth finish. Try using a trowel when finishing the surface.

For professional-looking edges, use a concrete edger. But do this within the first 15-20 minutes after application.

Note that the resurfacing material often creates a smooth finish which is not very advisable for sidewalks, indoor flooring, driveways and patios. However, you can scuff the surface using a long-handled broom and make full strokes across the concrete surface. Be sure to do this within 5 minutes after application when the mixture is still wet.

 

Step 5: Leave it for 2-3 days

Let it cure by leaving the area untouched for about 48-72 hours. When the surface dries completely, you will have a stronger and more beautiful, brand new floor.

concrete resurfacing floor
Image Credit to DRK Concrete

Depending on your taste, there are surface enhancers or decorative concrete resurfacing treatments you can use. You can even choose the appropriate seal coat to protect your new concrete surface.

In addition, there are also non-slip coatings that can prevent injuries and unwanted accidents, which are necessary  considering  concrete surfaces can become slippery when they get wet.

With decorative concrete resurfacing, you will have countless options for texture, colour, and patterns as well as a plethora of many different choices for resurfacing, patching and sealing systems.

It also includes acrylic concrete sealer for outdoor floors and clear epoxy sealing for indoors. You can also have matte or high gloss finish and non-slip grits when you choose to have decorative concrete resurfacing.

 

When should you do Concrete Resurfacing?

Concrete resurfacing is actually not designed to repair all concrete damages. This only works best with minor or slight floor damages.

Keep in mind that most concrete resurfacing materials are suitable only to a deep of 3/8 inch to ½ inch. Ergo, this is not suitable for concrete surfaces that are not structurally sound — chunks of concrete have lifted or sunk or broken and there is evidence of heaving. For this, you will need the area be replaced.

In addition, serious problems such as large, deep cracks running through the slab and disintegration of the concrete surface into powdery substances cannot be corrected with just the concrete resurfacing method.

Ultimately, concrete resurfacing is more economical and can be done  more quicker to do perform than replacing the concrete with new material. Plus, you have the option to put decorative concrete, to add character to your dull floor.

But to be sure that resurfacing is suitable to repair your concrete, consult with a concrete repair professional.