In principle most experts agree on how to recycle concrete and save money. But, there has been a view in the construction industry that crushing concrete is really only for large-scale stationary crushers.
Never has that been further from the truth than now. Crushing concrete on site with a mini crusher is very viable and makes strong financial sense.
But, before more of that. Let's go back to the basics of how to recycle concrete!
Understanding how to recycle concrete is an increasingly important skill as society seeks to reduce both the use of new materials and cease producing net carbon emissions.
The Importance of Recycling Concrete
When structures made of concrete are demolished or renovated, concrete recycling into new concrete, is an increasingly common method of utilizing the rubble. In fact, in the UK in 2019 over 90% of demolition materials including concrete is now being recycled. And, the UK government is targeting this to rise still further, within the next 5 years.
The Stages of Concrete Recycling
1. Transport and Acceptance at a Concrete Recycling Facility
Crushing facilities need good quality rubble to start with. They have rules on what they will accept from demolition sites, and they only accept uncontaminated concrete.
If you intend to recycle your concrete make sure it is free of general rubbish, wood, paper and other such materials. Metals such as reinforcing steel bars (rebar) are acceptable in the material.
2. Crushing and Sorting
Concrete aggregate collected from demolition sites is put through a powerful crushing machine.
The reinforcing steel is released and removed with magnets after crushing. It is then sorted into metal types, and is usually sold to be melted down for recycling elsewhere.
Other sorting devices are used to remove small amounts of unwanted contaminants. The remaining aggregate chunks are sorted by size. Larger chunks may go through the crusher again.
3. Grading
To sell the aggregate materials, the crushed concrete is further sieved over screens until piles are formed of standard sized ranges for stones/ particles. Once graded, the aggregate is stored in piles of the sizes which are specified by concrete mix-designers for use in new concrete of a required strength and aggregate sizing.
It is then ready to be sold for casting into new concrete.
Portable Versus Fixed Crushers at Local Concrete Recycling Facilities
The construction site manager can either hire-in a portable crusher, set it up on-site, and process the site demolition material on-site, or have it transported off-site to a local Concrete Recycling Centre.
Crushing on the construction site from which it was demolished using portable crushers makes sense for large sites, and those sites where there will be a demand for the aggregate during construction of the new structures.
In those circumstances on-site crushing/ recycling will usually reduce construction costs and minimize emissions from transport overall.
How to Do the Best Recycling for City-centre Sites
This can be very important for city-centre sites where high levels of air-pollution and noise are often already present. That's even before introducing additional construction traffic!
However, for a construction site with very little demolition, it may be cheaper and less polluting/ better for the environment to simply transport the little demolished concrete it produces off-site. The cost of, and emissions from, transporting and setting-up a portable crusher, may simply not be justified.
Construction Site Managers Need to Get Involved
It is the duty of the Construction Site Management to compare the pros and cons of off-site vs on-site concrete crushing as they apply to each construction site, and act appropriately. Many contractors follow good practice when decisions are made, not only on recycling concrete but many other recyclates. The method used to do this well is to prepare and continuously update what is known as a “Site Waste Management Plan” (SWMP).
The “Site Waste Management Plan” (SWMP)
SWMPs generally are reputed to save contractors significantly more money than they cost in staff-time to prepare. Very often the SWMP will make the biggest savings through concrete recycling. But, there are often many other demolition materials which will be recyclable with some ingenuity applied. The outcome is that by using the SWMP method, those also add to the savings which can be made financially, and environmentally, through recycling on construction projects.
Benefits from Reduced Pollution
The pollution avoided by on-site crushing, and later on-site concrete batching to reuse the recycled aggregates can be substantial, compared with transporting material to and from a quarry.
Plus, don't forget that reuse of the stone means in addition, that no longer is new quarry stone in such demand. Less has to be dug from quarrying the countryside, to provide that stone. That is a huge benefit for the environment over a period of time.
Crushing Plant Technology
Large road-portable plants can crush concrete and asphalt rubble at 600 tons per hour or more.
These systems normally consist of a rubble crusher, side discharge conveyor, screening plant, and a return conveyor from the screen to the crusher inlet for reprocessing oversize materials.
Compact, self-contained mini-crushers are also available that can handle up to 150 tons per hour, and fit into space-restricted site areas.
Concrete Recycling Trends
With the continuing development of self-powered tracked mini-crushers, crusher attachments on-site concrete processing is becoming more viable for much smaller volumes of concrete.
Crusher attachments are now available to be connected to various construction equipment types.
Fitting crushing capability to excavators, is moving the trend towards recycling on-site, with smaller volumes of material. As a result, on-site concrete recycling is growing rapidly.
Real-life Examples of Crushed Concrete Reuse
Smaller pieces of crushed concrete are used as aggregate (i.e. like using gravel) for new concrete, on the same construction projects from which they were demolished.
Wire gabions (metal-mesh cages), can be filled with crushed concrete and stacked together to provide economical retaining walls.
The Alternative to Concrete Recycling that Considerate Contractors Don't Wish to have to Contemplate!
The alternative to concrete recycling is usually to send the demolition waste to landfill.
This is universally unpopular, and not without good reason.
Landfills can cause many environmental problems such as air pollution and water contamination. That occurs even with the best management of landfills. They are inherently odorous, and hazardous to the environment storing up pollution which will almost inevitably escape and damage the environment one day.
Concluding “How to Recycle Concrete” – Why Recycling and a “Circular Economy” is Universally Applauded
Cost reduction, and environmental benefits, along with the minimizing the shortage of resources caused by the growth in construction, make a compelling argument for concrete recycling.
More and more contractors in many more countries are becoming aware of the importance of C&D waste recycling, and implementing it.
Mini-crushers versus Large-scale Stationary Crushers
Aug 3, 2014: Now let us get back to the fascinating debate about the new breed of mini-crushers and the new capabilities of this new and innovative crushing plant.
In this section, we use the example of equipment manufacturer and suppliers Red Rhino Crushers:
Mini crushers can get into the smallest of places and crush site concrete in-situ and exactly where it’s needed. There are now crushers which are tailor made for this role, and the high portability of the best available crusher equipment really comes into its own in such situations.
The use of the best mini crushers need far fewer movements of the crushed rubble around the site, than any other method, keeping costs low and providing the absolute minimum of interference with the rest of the operations on-site.
Image above shows the typical result from on-site concrete crushing.
The leading mini crushers can work in far smaller spaces than a traditional large scale crusher, yet still achieve up to 45 tonnes per hour of valuable crushed stone ready for re-use in site applications.
The leading UK manufactured, mini crusher range as their name suggests, are said to be built to be strong and tough, and capable of crushing even the hardest rubble.
Existing owners of this leading brand have recognized that purchasing and maintaining a mini crusher can really save them money. The running costs are stated to be in the £100’s not £1000’s per year. This is considered to be a very viable alternative to the traditional large-scale crusher approach.
“The Opportunity for Site Managers to Reduce Costs with Mini Crushers is substantial”
The construction industry currently (2014) produces 120 million tonnes of waste every year. Around 20 million tonnes of this waste ends up in landfill with no reuse and no intrinsic value.
In financial terms the UK is spending £4bn annually to dump waste in the nations landfill sites.
Why continue to pay all those costs? They are currently very high, and are rising, with increasing landfill tax and fuel costs, When you can crush your own concrete and re-use the crushed material, or better still – sell it?
In many cases, in financial terms, it means that crushing just 15 tonnes of rubble can easily save at least £600 compared to dumping it. So ,why wouldn't you want to know how to recycle concrete the best way!
Jason Purllant, Sales and Marketing Manager, of Red Rhino has reported recently that, with the increasing pressure to recycle waste, sales volumes of their plant are increasing rapidly. But it’s not just in the UK market that is taking off for them.
Jason says he receives internet enquiries on how to recycle concrete, from all over the world. The world market is now focused on recycling concrete…
“Don't be left behind. We need to be doing the same in the UK. There are limited landfill opportunities and these are only going to become rarer and more expensive.”
The UK only recycles 15% of all the construction waste it produces (2013 figures – it's better now!) compared to Denmark where recycling is reported to have reached 90%.
Jason pointed out that we have a long way to go to catch up on our European neighbours. This problem will not go away on its own, but contractors have the solution available to them.
This market is set to grow over the next 5 years with fuel prices rising and landfill tax rising by over £8 per tonne each year (now in 2019 the Landfill Tax is approaching £100 per tonne) .
Our Case Study: Red Rhino Products
Red Rhino Products concrete crushing products work on a very simple action that calls for two jaws, set in a “V” shaped notch configuration, to be powered together.
Material; that is rocks, bricks, kerbstones etc., entering the top become progressively crushed as they slip down into the “V” until they are small enough to fall through the gap at the bottom.
The size of the finished material is governed by the width of the gap at the bottom. Output can vary from 10 mm to 140 mm depending on the settings of the jaws.
This means that the grading stage for the crushed aggregates, as described above for traditional crushing systems is no longer needed.
The Red Rhino Products range starts with the 750kg 2000 series increasing in size to the 10,000kg 7000 series. We have a range of crushers to suit every application and budget.
Their most popular machine is the 5000 series, which boasts a massive 20 tonnes per hour capacity, yet will fit easily on the back of standard 3 tonne rated plant trailer.
The Future
The debate over how to recycle concrete is over. It's now simply necessary to do it, and do it the easiest lowest emissions and cost way. The cost of being in crushing market is set to grow still further, following the general trend of the construction industry in 2019.
Increasing EU pressure, and good old-fashioned common sense, is forcing all businesses to reconsider how they handle their construction waste.
Jason said, it's simple:
“Build Red Rhino Products crushing equipment into your Construction Site Waste Management Plan (SWMP), from the start.”
Before you say:
“He would do wouldn't he. He's their Sales and Marketing Manager”!
Do yourself a favour! Suspend your thoughts for a few moments to test-out his assertion!
Why not visit their website?
It's where prospective customers are given the opportunity to review their full range of crushers. They give details of each individual specification, as well as providing visitors with the chance to see explanatory videos of the products, in action.
If interested, do click the link which follows, to visit the Red Rhino Products concrete crushing products web site for more information.
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