Here is a guide on concrete removal and practical demolition options.
Concrete is an indispensable construction material that’s widely used across a wide array of projects. It can be used for fresh constructions as well as for restoration purposes (for worn-out concrete). Yet, certain concrete structures may need to give way to remodeling work.
Demolition is the process through which concrete is gotten rid of. Whatever your reasons for demolition are, one thing remains; the need to tear down the concrete structure. Here, we’ll be discussing extensively demolition methods used for concrete removal.
If you plan on embarking on a demolition project, you’ll find this article useful towards achieving such an objective.
Common Conditions Leading to Concrete Removal and Demolition
Several reasons call for concrete removal and demolition.
Some of the most popular include sunken slabs, deep & widespread cracks, frost heave on concrete slabs, and significant spalling.
Of course, concrete demolition may be required during remodeling work. Old buildings and worn-out concrete structures also need to give way.
This is one of many conditions that may require concrete removal and demolition.
Here, the subgrade may be faulty due to a mixture of loose dirt. As the water slowly percolates, through the soil, it causes settling of the loose dirt beneath the concrete structure.
This results in a situation where there’s no support leading to sinking. To remedy this situation, sunken slabs will have to be fixed.
Deep and Widespread Cracks
The condition of the subgrade is also likely to result in widespread cracks on concrete.
As heavy machinery such as trucks passes over the surface, it results in cracks that need to be fixed. Subgrades may be eroded or compacted. Whatever the case is, such concrete needs to be demolished and repaired.
Frost Heave on Concrete Slabs
Frost heave is a condition that occurs when groundwater freezes. This causes an expansion which eventually takes its toll by creating uplift on concrete surfaces. Fixing this damage will require the removal of faulty concrete.
Spalling is another condition where certain areas of concrete are cracked and delaminated from the substrate. Here, it’s more economical to have such concrete removed or demolished and new resurfacing performed.
Remodeling jobs are of various kinds. Whether you wish to create more space by bringing down concrete structures or simply wish to alter current designs, demolition will play a key role in achieving such.
Old and Worn-Out Concrete Structures
There are old and worn-out concrete structures that pose varying degrees of risk. To eliminate such risk will be to bring down these old and worn-out structures.
This is one of several reasons to carry out the procedure.
Would a Sledge Hammer Suffice?
One concrete demolition tool that readily comes to mind is the sledgehammer. Although this has been in use for many centuries, a lot of improvements have been made in terms of tooling.
Sledgehammers are still deployed for certain demolition work. However, there are better tools available.
Such equipment basically consists of power tools such as pneumatic hammers, chipping hammers, expansive demolition agents, demolition hammers, and mounted breakers.
Others include hydraulic hammers, diamond wire saw, rotary hammers, and hydraulic concrete crushers.
Hydraulic splitter and pavement breaker are additional tools among several others used for concrete demolition jobs. Each tool type needs to be used in a certain way to obtain expected outcomes.
Does Concrete Type Matter?
When it comes to concrete demolition methods, more light needs to be shed on the type of concrete involved.
Does concrete type matter or influence the demolition method used? Different types of concretes will have varying degrees of strength. However, that doesn’t play any major role in deciding what demolition method to use.
So, what are the types of concrete? There are several! They include volumetric concrete, normal strength concrete, ready-mix concrete, plain or ordinary concrete, air-entrained concrete high-density concrete, pre-stressed concrete, lightweight concrete, and reinforced concrete.
Other types include precast concrete, shotcrete concrete, decorative concrete, asphalt concrete, rapid-set concrete, glass concrete, and smart concrete.
There is also roll compacted concrete, pervious concrete, limecrete, and pumped concrete.
Concrete Demolition Methods
Concrete demolition is one action that can be performed through various methods.
Whatever the method, the result is to have the concreted dismantled or removed. The method used is largely determined by the site condition, thickness, height of the structure, and age of the building among others.
These factors will be discussed shortly but for now, let’s discuss the concrete demolition methods.
These methods include blasting or the use of explosives, pneumatic & hydraulic breakers, ball & crane methods, pressure bursting, dismantling & demolition using hand-held tools.
Blasting or Use of Explosives
This demolition method is mostly reserved for huge structures. In other words, it’s best used for demolition projects where large volumes of concrete need to be demolished.
Here, explosive materials are strategically placed along key structural components to ensure it implodes uniformly.
This type of demolition is mostly performed on high-rise structures and buildings especially those found in cities. In most cases, you’ll find nearby structures which require the adoption of a more tactical approach to demolition.
In terms of chemical composition, two categories of explosives are used; composite and molecular explosives. Examples of composite explosives include ammonium nitrate-fuel oil (ANFO).
On the other hand are trinitrotoluene (TNT) and nitroglycerin (NG) being examples of molecular explosives.
Pneumatic & Hydraulic Breakers
Concrete removal and demolition can be performed using the pneumatic and hydraulic breaker procedures. These are more popular with jobs such as foundations, pavements, and bridge decks.
Pneumatic and hydraulic breakers are machine mounted.
This equipment works by delivering around 100 to 20,000-foot-pounds at 300 to 800 blows per minute. This is significant as concrete structures succumb within a short amount of time.
Pneumatic and hydraulic breakers come with a variety of settings that enable easy adjustments.
Underwater concrete structures can also be demolished using this procedure. As stated earlier, the condition of your demolition task will determine what demolition procedure is used.
In other words, this method or any other can be used based on the situation on the ground.
Ball & Crane Method
The ball and crane method of demolition is one of the most popular for the demolition of structures.
You’re likely to have seen this in action. As the name suggests, the ball and crane demolition method involves a setup where a heavy ball (weighing about 13,500 pounds) is attached to a crane.
This crane swings the ball at the concrete target which delivers a powerful blow, thus shattering or breaking up concrete. The ball and crane demolition method works in two ways; the ball is either swung at a concrete structure or dropped on it.
Either way, the force breaks up the structure.
There are certain downsides associated with its use. First, you’ll have to contend with the loud noise and vibration created. This also includes dust raised as a result of the demolition action.
As is the case with some demolition methods, this isn’t so ideal for certain demolition tasks.
Pressure bursting seeks to demolish concrete more efficiently by eliminating dust and noise. This is an effective demolition technique that’s controlled.
Pressure bursting can be performed in two ways; mechanical and chemical.
For mechanical bursting, the target is to split concrete under high power using machinery known as a splitting machine. The pressure required is supplied by hydraulic systems which are powered by a motor.
Chemical pressure bursting follows a different format.
Here, an expansive slurry is fed into boreholes that are uniquely patterned. With demolition completed, concrete can easily be removed by hand or heavy equipment such as a crane.
One thing is common with both pressure bursting techniques. Holes need to be bored through the concrete structure. This is followed by lateral force application.
Dismantling is another concrete removal and demolition method where concrete is cut into manageable bits.
Water jetting is one popular technique under this method that creates lesser sound and dust. There’s also limited vibration.
Demolition Using Hand-Held Tools
This is one of the most rudimentary forms of structural demolition. It’s best applied to smaller structures and involves the use of hand-held tools like sledgehammers and power tools like those mentioned earlier.
When it comes to structural deconstruction, this demolition method is the strategy applied. Here, demolition takes a longer time to complete.
However, the value is seen in the materials salvaged which can be repurposed, reused, or sold.
Factors Affecting Demolition Techniques
Factors affecting demolition techniques used include site condition, thickness, the height of the structure, and age of building just to mention a few.
A demolition consultant will determine the best applicable demolition strategy based on these factors as they reveal a lot about a concrete structure.
To know what demolition method best fits your concrete structure, you’ll need to call for an onsite assessment. Inspection costs are likely to be incurred as well.
Concrete removal and demolition methods differ. The different types available have been supplied above. We’ve also seen that not every demolition method suits all job types.
Some of the influencing factors have also been supplied above.