Concrete recycling | Methods and Usages

Introduction to concrete recycling

Concrete recycling is a good way to protect the environment.

In almost all buildings, people can see concrete.

Because of its versatility, ease of handling, and aesthetics, its use is the most widely used in buildings.

However, it is also one of the main pollution sources in the atmosphere.

Among them, the main reason is that carbon dioxide emissions from the cement industry account for about 8% of global carbon dioxide emissions.

Moreover, the extraction of sand and gravel required to make concrete can also have a huge impact on the environment. Therefore, people protect natural resources and the environment by reducing the mining of gravel and sand.

And this method is to recycle concrete.

Next, this article gives you detailed information about concrete recycling.

Related Articles:

Cement vs Concrete, whats the difference?

Concrete recycling is feasible

In the early stages of many construction projects, people need to carry out demolition work.

Moreover, this may include demolishing concrete foundations, driveways, sidewalks, walls, and other architectural elements. And in this process, people wasted a lot of heavy construction materials.

Among them, these include concrete.

However, people can recycle and use concrete in many ways.

Moreover, old concrete is a good material for producing recycled concrete aggregate.

However, the recycling process of concrete varies.

Generally, people receive broken, impurity-free, and crushed hardened concrete from the source.

Meanwhile, the best recycling method for each project depends on the size and shape of the recycled concrete blocks.

And the reuse of concrete saves the cost of transporting the concrete to the landfill. Moreover, this replaces raw materials. Therefore, concrete recycling reduces the environmental impact of the project. For example, it can replace gravel.

Moreover, old concrete pavements are usually good materials for producing recyclable concrete.

Therefore, the old concrete is completely recyclable. Moreover, its recyclability is 100%.

Next, let’s take a look at the characteristics of recycled concrete.

Characteristics of recycled concrete

The crush-ability of recycled hardened concrete is similar to that of natural rock.

Moreover, it is not affected by the grade and quality of the original concrete.

Meanwhile, except for the worst-quality raw concrete, the recycled concrete aggregates produced by all other products can pass the conventional aggregate test.

In fact, recycled concrete aggregate includes not only the original aggregate but also hydrated cement slurry.

Moreover, compared with similar original aggregates, its paste has reduced specific gravity.

Meanwhile, its porosity increased.

Because of the higher the porosity of RCA, the higher the absorption rate. Therefore, these characteristics are good advantages of concrete recycling.

In fact, the recycling of concrete is also divided into types. Then, let’s understand the following in detail.

Related articles

Concrete vs pavers, what’s the difference?

Types and functions of recycled concrete

Generally, there are different types of recycled concrete depending on the source of recycling.

Moreover, their characteristics and uses are also different.

1. The foundation of the new asphalt pavement: people break it down through the process of gravel. Moreover, the process includes decomposing the old concrete pavement. And then, people use them as an asphalt base.
2. Outdoor surface: The effect of crushed concrete is similar to that of permeable concrete.

We all know that permeable concrete is great for driveways, parking lots, and sidewalks. And this reduces the runoff that the rainwater drainage system has to deal with.

Besides, permeable concrete also helps replenish the groundwater level.

So, in some outdoor areas, people can use crushed concrete to create porous surfaces.

3. Bed base material for public ditch: recycled concrete can replace gravel to cover the bed base of the ditch.

Moreover, this can help drainage.

4. Used as concrete aggregate: recycled concrete can replace the new aggregate in the concrete mixture.
5. Erosion barriers and reef habitats: People can place large pieces of broken concrete along the river bank. And this can control erosion.

Or, people can put them on the coastline.

Moreover, this can form the basis of coral reefs.

However, people must analyze the chemical composition of old concrete before putting it into the aquatic environment.

Related article

Guice on commercial flooring

Overall perspective

In fact, for recyclable materials that have more limited uses than the original materials, people can recycle them at a rate of 60%.

Moreover, people can use these fragments as basic materials for roads and other structures.

Besides, people can also replace the gravel in the concrete with the aggregate leftover from the crusher.

Therefore, recycled concrete can replace the natural stone.

However, in this process, people need to comply with the particle size analysis method specified by the project.

Among them, the guidelines of the German Structural Concrete Committee stipulate that the proportion of recycled aggregates cannot exceed 50%.

However, a material test in Switzerland in 2006 showed that even if people use more than 90% of waste aggregates, they can produce high-quality concrete.

Moreover, the resulting concrete can maintain structural features very similar to traditional concrete.

Related article

Outdoor concrete table & other concrete products

Benefits of concrete recycling

With the reduction of raw resources, the demand for high-quality aggregates has increased.

So, this created the concrete recycling industry.

Then, what are the benefits of concrete recycling?

Sustainable development

Recycled concrete can provide sustainability in several different ways.

First of all, recycled concrete itself is aggregate.

Moreover, people can recycle any embedded metal.

Besides, recycled concrete can also replace other materials. For example, gravel.

Therefore, this reduces the extraction and transportation of natural materials.

And it reduces the impact on the environment.

Related article

Overview of concrete mantenance

Reduce transportation costs

Usually, people can recycle concrete near demolition or construction sites.

Therefore, people do not need additional waste disposal.

At the same time, people do not need to transport new materials from the mining area.

Therefore, concrete recycling reduces the project’s need for transportation.

Thus, this reduces the cost of transportation.

Reduce the need for landfills

Because people recycle concrete near demolition or construction sites, waste concrete will no longer enter the landfill.

Therefore, this reduces the amount of material that people must landfill.

Thus, this reduces the demand for landfills. Similarly, concrete recycling saves builders the cost of waste disposal.

Moreover, this not only reduces construction waste but also helps extend the life of the landfill.

Good for the environment

The process of carbonization can occur from the surface inward in all concrete.

Moreover, in the process of crushing the concrete to produce recycled concrete aggregate, the uncarbonized concrete area will be exposed to atmospheric carbon dioxide.

Therefore, concrete recycling can absorb a large amount of carbon dioxide from the environment.

Thus, this has great benefits for the environment.

Conducive for builders to obtain LEED green building certification

The LEED® Green Building Rating System recognizes recycled concrete in its points system.

In addition, Materials and Resources point out that：

Designate that at least 25% of building materials total at least 20% of the weighted average of post-consumer recyclable materials.

Or, at least 40% of the weighted average of industrial reuse content materials using recycled aggregates instead of extracted aggregates will become post-consumer products. Meanwhile, builders who meet this indicator can earn LEED points.

So, if builders are seeking LEED green building certification, they can earn points by using recycled concrete.

Get credit

If at least 50% of the quality of the construction and land clearing waste disposed of in the landfill is available, construction waste management can obtain credit.

Replace other raw materials

In some cases, new employment opportunities will be created in recycling activities, while in other cases they will not exist.

Improve road performance

1. People use recycled concrete to improve road performance. And the improved performance mainly includes the following:
2. Foundation stability
3. Sharp edges
4. Rough texture
5. Secondary gelling muscles
6. Concrete strength
7. Partially replacing the original fine aggregate with RCA may increase the compressive strength of concrete.

Concrete recycling vs waste concrete

Next，Let’s have a see together.

Generally speaking, the cost of transporting concrete to the landfill is US$0.25 per ton.

Moreover, the cost of disposing of waste concrete is as high as $100 per ton.

Meanwhile, these costs are still rising.

Besides, the supervision of landfills is becoming stricter.

However, one can remake concrete into crushed aggregate.

In this way, people save the above costs.

Moreover, people can use these gravel concrete to make new buildings.

Therefore, many builders and people doing demolition work will seek these concrete recycling methods.

Moreover, more and more contractors are incorporating recycling into their operations.

Therefore, people can save a lot of money and work by recycling concrete.

So, how do you recycle concrete?

Next, Let’s have a see together.

How to recycle concrete

The quality of concrete that people use depends largely on the quality of recycled materials.

Therefore, the work of recycling concrete is very important.

Generally speaking, people must remove steel bars and other embedded objects in the waste concrete.

Moreover, people must be careful to prevent other materials from contaminating the concrete.

For example, asphalt, soil, clay balls, chloride, glass, gypsum board, sealant, paper, plaster, wood, and roofing materials.

When people collect the concrete, they pile the waste in the crusher.

In this way, people shred the waste into small pieces.

Then, people put the crushed concrete into a set of conveyor belts.

Moreover, these magnets will remove ferrous and non-ferrous metals from the concrete.

After that, the conveyor belt will make the second round of impact on the crushed concrete.

And this breaks the material further.

Then, the broken concrete will enter the screening machine. And can divide them into small pieces of similar size.

Moreover, it separates dust and dirt from the rock material. Thus, this makes the filling cleaner.

And the final product will be more refined.

In this way, people can use them for various purposes.

For example, as roadbed or aggregate.

Sometimes, people can also recycle powdered concrete.

However, this separation process is more complicated. Moreover, this may result in more pollution from smaller by-products.

Below, we briefly summarize the above steps to make them clearer.

Steps of concrete recycling

When recycling old concrete from demolition, the most common steps are as follows:

Step 1: First, people crush large concrete blocks with special industrial equipment.

And the equipment people often used are jaws and large impactors.

Step 2: Screen them to remove any dirt or contaminating particles.

At this time, other processes and equipment may be required. Such as water flotation, separators, and magnets.

And they can further remove other impurities in concrete.

Step 3: The screening machine divides the concrete into large pieces and small pieces.

Next, let’s take a look at the main applications of concrete recycling.

Application of concrete recycling

In fact, recycled concrete is used in the same way as new materials.

When people need to use new aggregates, combine recycled concrete with original aggregates.

However, there are some things people need to pay attention to when using it.

Suggestion for use

Generally, when natural sand is needed, people can replace up to 30% of natural crushed coarse aggregate with recycled concrete.

Moreover, this will not affect any mechanical properties of the concrete

However, as the number of replacement increases, the drying shrinkage and creep of concrete will also increase.

Meanwhile, its tensile strength and elastic modulus will decrease.

However, the change in tensile strength is not obvious.

It is suggested that when using recycled concrete, people should perform batch processing based on pre-wetting under nearly saturated surface dry conditions.

And, this can make the workability of concrete recycling the same as that of conventional concrete.

Moreover, people usually increase the slurry content or water reducing agent to obtain the same slump and water-cement ratio.

Below, let’s take a look at where people often use recycled concrete.

Specific usages of concrete recycling

1. Permeable paving for sidewalks, driveways, and other outdoor hard surfaces: broken concrete can form a stable, porous surface.

Therefore, the road can filter out rainwater. Moreover, this reduces the management of the rainwater drainage system. Meanwhile, this helps to replenish groundwater.

2. The foundation of the new asphalt pavement: For the pavement, there are no restrictions on the type of pavement that can be recycled concrete. For example continuously reinforced pavements, airport pavements, pavements with a thickness of more than 17 inches, etc.
3. The bed base material of the trench containing the underground utility pipeline: the utility trench is covered with gravel oven. And this can help drainage. Moreover, recycled concrete is a good and cheap alternative to gravel.
4. Control riverbank erosion: People place larger pieces of broken concrete along fragile riverbanks or ditches. And this helps control erosion.
5. Garden coverings: properly crushed and reasonably classified concrete can replace river rocks as ground coverings and gravel for ground coverings.
6. Filled wire mesh: People use recycled concrete to fill the iron cage with gravel. And this can be made into a decorative and functional privacy shielding wall or retaining wall.
7. Build a new marine coral reef habitat: people can put large pieces of recycled concrete on the sea. And this can lay the foundation for a new coral reef.

In general, it has a wide range of uses.

Related article

All about stamped concrete

Conclusion

Because of the versatility, ease of handling, and aesthetics of concrete, its use is the most widely used in buildings.

However, in the early stages of many construction projects, people need to carry out demolition work.

And this will generate a lot of waste.

Fortunately, these concretes are 100% recyclable.

However, for recyclable materials that have more limited uses than the original materials, people can recycle them at a rate of 60%.

Basically, the crush-ability of recycled hardened concrete is similar to that of natural rock.

In general, people using recycled concrete have many benefits: sustainable development, lower transportation costs, reduced demand for landfills, energy-saving, etc.

Moreover, people use recycled concrete to improve pavement performance.

Compared with the disposal of waste concrete, concrete recycling can save a lot of work and costs.

However, the quality of concrete that people use depends largely on the quality of recycled materials.

Therefore, the work of recycling concrete is very important. People can refer to the above steps for recycling.

Moreover, because of its better performance, waste concrete is also widely used.

That’s all for concrete recycling today.

If you like this article, please share it with your friends.