Concrete recycling: standards and solutions for quarries

Concrete is the most frequently used building material.

And all over the world! Composed of a mixture of aggregates, sand and water bonded by a binder, usually cement, concrete is a real challenge when it comes to recycling.

Concrete production is estimated at one tonne per inhabitant. Each tonne alone emits (on average) 575 kg of CO Translation? Concrete accounts for 5% of the planet's greenhouse gas emissions. Not to mention that its production requires large quantities of water and sand.

Nevertheless, concrete is a building material with many uses and advantages that would be a shame (if not impossible) to do without.

To counter the pollution emitted by concrete while extending its life cycle, concrete recycling has already proved its worth.

And quarries has a role to play! Synaxe takes a look at how concrete recycling can help your quarries. 

Concrete recycling and recovery: where do we stand?

There's a reason why concrete is the most widely used building material in the world! Its durability, excellent thermal properties and ability to take on any shape make it a material of first choice.

And it's nothing new! In fact, concrete was used as far back as antiquity. It was even considered a military secret by the Egyptians and Phoenicians. It was between the 19th and 20th centuries, however, that the use of concrete accelerated, making it one of the world's most important materials - long before there was any talk of recycling concrete.

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Result: 

• Today, 80% of single-family homes have concrete floors;
• 70% have concrete block walls;
• 60% have concrete wastewater and stormwater pits;
• 1 in 2 tiles in the Paris region is concrete.

The only drawback is that, while the raw materials that make up concrete are widely available on the planet (sand, water), they are becoming increasingly scarce. What's more, their use is becoming more and more expensive, impacting the environmental balance.

As you can see, recycling concrete is a necessity for both ecological and cost reasons. Sorting and recycling reduces the amount of waste generated. And so much the better, because landfill disposal - too - is expensive.

Another advantage: recycling concrete helps to protect the environment by reducing the amount of natural raw materials used, for example, in road repair. And contrary to popular belief, recycled concrete is a quality material! 

According to some concrete recycling experts, it outperforms road waste. " It can even replace new natural materials treated with a hydraulic binder, because when the concrete is crushed, parts of the cement are released and rehydrated by the natural humidity of the crushed waste.

Circular economy: recycled concrete has it all!

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Nothing is lost, everything is transformed.

Concrete recycling is the perfect example! Today, it's an effective way of meeting the ever-increasing needs of the construction industry. On the one hand, these needs are constantly increasing due to demographic growth; on the other, they must meet new environmental and regulatory requirements - RE 2020 being at the top of the list. 

As a reminder, the new Environmental Regulations (RE 2020), which came into force last January, have imposed major changes on the construction industry - not least in terms of recycling (and not just of concrete). 

Objective: to reduce the carbon impact of construction and renovation on the planet. 

How? By promoting the circular economy, and consequently reuse (to name but one). As the world's leading construction material, recycling concrete quickly became an obvious choice. 

For good reason: recycling concrete is a trendy action that makes it possible : 

• Saving resources 
• The "creation" of a responsible, high-quality alternative material 
• Developing local production 
• Optimized transport thanks to double freight

Concrete waste: a second life through concrete recycling

In practice, concrete recycling involves two types of concrete streams:

• Concrete from deconstruction.
• Concrete from manufacturing processes - from prefabrication plants, ready-mix concrete production units and site returns.

The majority of concrete waste, i.e. used concrete, can benefit from concrete recycling: fresh or hardened concrete, manufacturing scrap or concrete waste returned by construction sites.

Good to know: recycling concrete does not necessarily require a transformation operation. Recycled concrete can be reintegrated on site (in situ) to enable the manufacture of new products. Even if the concrete has hardened, non-binding of additional sorting and via simple crushing plants. As you can see, even during the recycling phase, concrete has a number of advantages, not to mention a certain flexibility of use. 

For optimal concrete recycling, it's best to sort your concrete!

Of course, concrete isn't the only material recycled on a building site! Let's face it, most materials today are recycled. So, during deconstruction, sorting is essential to recover as much used concrete as possible for recycling. This separates concrete from other materials. 

The good news is that sorting techniques are improving all the time, saving time and increasing efficiency. This is because every recycled material represents a boost not only for the environment, but also for the finances of the company behind the recycling. In fact, given the importance of recycling concrete and all other building materials, a waste diagnosis has been mandatory since January¹, 2022, prior to the deconstruction of any building considered "important".

This optimizes sorting quality, and at the same time, the concrete recycling rate.

Did you know? The concrete industry is committed to improving concrete recycling! 

Aware of the importance of recycling concrete, the concrete industry is working to improve the design of construction systems and products. 

This commitment has led to the revision of three standards that affect concrete recycling: 

• Aggregate standards NF EN 12620 of June 2008 and NF P18-545 of September 2011. Both specify the characteristics and properties of recycled aggregates. 
• Concrete standard NF EN 206-1/CN of December 2012, which authorizes the use of recycled aggregates from deconstruction sites in the manufacture of concrete.

Similarly, the French anti-waste law for a circular economy (AGEC) also promotes concrete recycling. How does it do so? Since January 1, 2022, the extended producer responsibility (EPR) scheme has applied to construction products and materials used in the building industry. This new obligation is intended to lead to greater recycling not only of concrete, but also of all mineral construction products that generate inert waste. To achieve this, all players in the construction industry can now rely on ECOMINERO. An eco-organization whose mission is to improve inert waste recycling - including concrete recycling. 

Concrete recycling and quarries : what's the link?

In 2019, aggregates derived from the recycling and reuse of inert waste from construction sites covered 28% of the needs for the construction and maintenance of infrastructures and structures, according to the ECV (Engagement pour la Croissance Verte) report. 

Relating to the recovery and recycling of inert construction waste, the ECV is currently aiming for a recycling rate of 90% by 2028. And in practice, concrete recycling will contribute to this target. For example, the recycling of demolition concrete alone represents a recycling potential of 19 MT(see visual opposite). 

Concrete recycling can be achieved in three different ways. Via:  

• Recycling at quarry as backfill
• Reuse directly on construction sites
• Recycling platforms

Concrete recycling at quarry, how does it work?

Recycled concrete is derived from 247 million tonnes of construction waste, 90% of which is inert waste: earth and gravel, demolition concrete, asphalt, bricks, mixes, etc. quarries already handles a large proportion of this waste via two methods: recycling and redevelopment of quarries for the non-recyclable fraction. For your quarries, concrete recycling is a complementary activity that makes you more competitive. 

In concrete terms, recycled concrete - produced on your sites from external construction waste - represents a resource that complements natural resources. It enables : 

• optimize the exploitation of deposits;
• use the resource as efficiently as possible;
• extend the life of natural deposits. 

In practice, building contractors have to send their inert construction and demolition waste to aggregate recycling centers or to Inert Waste Storage Facilities (ISDI). 

By equipping yourself with a recycling center capable of sorting concrete and all other materials, you can meet the real need for inert waste management - stone, concrete... A need that is constantly increasing due to regulations and the unavoidable shift towards a circular economy - less polluting. 

Of course, receiving and handling concrete waste or scrap requires a dedicated organization. With this in mind, many quarries sites have set up reception and storage areas for concrete from demolition operations, awaiting reprocessing/recycling. 

Similarly, not all concrete can be treated in the same way. While non-ferrous concrete simply has to be re-crushed, ferrous concrete has to be further sorted to remove the scrap. Generally speaking, concrete returns from construction sites are collected in skips where they harden into large blocks - before being crushed. Finally, once crushed, the recycled concrete is screened to produce cuttings tailored to the needs of the market - mainly that of public works. 

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Conclusion

Collected and processed close to its consumption basin, recycled concrete is the perfect answer to new regulatory imperatives and circular economy criteria, which increasingly require the use of a proportion of recycled materials with very low carbon impact. Recycling concrete also means undeniable savings in resources, notably water, but also sand and gravel. 

A major issue that the summer of 2022 will put under the spotlight due to an unprecedented drought! Technically speaking, recycling concrete will enable you to take action, to save money, but also to add value. And not just concrete! 

Taking part in concrete recycling is a great opportunity to showcase your quarries commitment to the circular economy and waste reduction. 

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