Competition - Traditional concrete rubble processors
Mining techniques form the basis for all mineral crushing techniques.
Crushing equipment is developed to fragment e.g. coal and metal ores. When making use of these types of machines for concrete rubble, the process is identical: large concrete chunks (construction parts, concrete paving stones, etc.) are reduced to small concrete particles (concrete rubble granules).
By using traditional crushing methods, approximately 45% of the original concrete rubble mass will be released as 0 – 4mm crusher sand. For this mass, no serious use has yet been found to reduce its value to ‘zero to negative’.
Moreover, the small amount of cement stone that will be released, will also be polluted with fine silicate particles and can no longer be used for making traditional cement. These traditional crushers are very heavy-duty machines, using tremendous force and pressure as they are designed to break through everything.
The SmartCrusher, on the other hand, does not break straight through the sand and gravel but only crushes the cement stone, the paste that glues sand and gravel together.
Literature studies show that ‘Dutch sand and gravel’ has a strength of approximately 200 MPa (200 N/mm2
). Our own research has shown that cement stone has a compressive strength of only 14 MPa. Due to the fact that SmartCrusher does not crush the much stronger, unhydrated cement, sand or gravel, but only the weaker hydrated cement, the SmartCrusher can be considered as a low-pressure crusher with a significantly lower weight than the traditional crushers.
Another matter is that the cement in concrete will never completely react with the mixing water, which means that all the cement hydrates into hydrated cement, also called cement stone. In the Dutch trade journal Betoniek, issue 6/3 of March 1983, it is shown that substantial quantities of new cement in concrete rubble are at issue.
Betoniek 1983 - How much unused cement can be released from concrete rubble.
In this Betoniek issue on page 4, figure 4 shows plainly how much unused cement can be released from concrete rubble.
If in those days the concrete rubble was made with Portland cement A and a water/cement factor (wcf) of 0.4, it shows that the degree of hydration is 60% maximum, in other words the concrete rubble contains at least 40% of new, unused cement.
The low-pressure operating principle also results in a much lower energy consumption and it makes the SC less sensitive to faults.
In its report of September 2013 (Prioritizing perspectives concrete chain sustainability (Delft, September 2013)), Annex B-8 on page 50, CE Delft states under the heading ‘Reduction Costs’:
“Due to its operating principle the forces that a smart crusher is exposed to are approximately 10% of the forces a regular crusher has to withstand”
Currently, research is again being done into a well-known method to break down concrete rubble into sand, gravel and cement stone sludge in an aquatic environment by using electric high voltage
. In addition to the high energy consumption involved in breaking down concrete rubble and drying the cement stone after that, all the still unhydrated cement is lost
in the process. This technique, to which due attention was paid in the previous century, does not presently appear to be an alternative to the ‘SmartCrushing’ technology presented by SmartCrusher BV.
To summarise, the advantages over traditional crushing are:
- As the SmartCrusher does not crush sand and gravel, the cement and hydrated cement will not become polluted by fine broken sand and can straight away be reused to produce new cement/paste.
- ‘Smart Crushing’ of concrete rubble does not leave any worthless residual fractions, unlike with traditional processing.
- The unused cement can straight away be reused in concrete. In a variety of ways, the hydrated cement can contribute to the realisation of making concrete circular as well. This will be described in more detail in ‘SmartCrusher quarry 2020’
With the technology presented by SmartCrusher BV, using the hydrated cement that is released when ‘SmartCrushing’ the concrete rubble and by using climate-neutral electricity from bio-fuels, cement can be produced 100% CO2-neutral, resulting in closed-loop recycling.
Experience from the European FP7 C2CA project, in which Delft University of Tehnology has a leading role, has shown that only 6% of traditionally crushed cement-rubble fines can go back into the cement kiln.
With SmartCrusher 100% must be attainable.
- The sand and gravel retrieved from concrete rubble by using the SmartCrusher, is better in new concrete than new sand and gravel. An increase in strength by 25% is the rule rather than the exception.
In addition, this extra strength with SC sand and gravel can be used to reduce approximately 15% cement (and thus it reduces CO2 by 15%).
Also see the TU/e report (page 20) and Cement 2013 (page 5)
- When compared with traditional crushers, SmartCrusher uses about 85% less energy for each processed tonne of concrete rubble.
- With the SmartCrusher it is possible to recycle 100% of steel-fibre concrete. Steel fibre is the concrete reinforcement of the present and of the future. Several reports refer to it as a serious way to make concrete much more environmentally friendly (see Prioritizing perspectives concrete chain sustainability (Delft, September 2013) ‘different reinforcement method’ no 11). It is very hard, or sometimes not possible at all, to remove steel fibre from concrete rubble with the traditional crushing techniques. And even if it is successful, the fibres are crooked (Recyclability of Steel Fibre Reinforced Concrete (BEwerken - September 2013)).
The steel fibres retrieved using the SmartCrusher remain straight and are reusable straight away!
From our own research it also has been proven that concrete reinforced with polypropylene fiber clean and completely can be released from concrete. The same result is expected from asbestos-cement sheets.
- In the rare case that a piece of (window-frame) timber or PVC pipe should end up in the SmartCrusher, it will not be shattered but it will leave the SmartCrusher virtually unchanged! Traditional crushers smash this material to hard-to-remove small splinters, which are highly unwanted in new concrete.
Moreover, the SmartCrusher is less prone to process failure than traditional crushers.
- Expectations are that the SmartCrusher will be able to process radioactive concrete rubble into clean sand, concrete flow and activated barite gravel.
The activated, though clean barite gravel, which is less than 50% of its volume, will be reusable for new nuclear applications. At worst, there will only be a 50% volume reduction, which, in its turn, is considered an immense improvement.
After a half-life of only 2 days, the sand and ‘cement’ will be radiation-free and suitable for normal civil applications.
- Big economic advantages can be gained by including the SmartCrusher in BREEAM, the Dutch Green Building Council and Lansik’s CO2 performance ladder.
Research at TU Delft and Leiden University shows that SlimBreken is currently the only concrete recycling technique where serious environmental benefits can be achieved. It also appears that smart crushing roughly halves the price of newly made concrete with SlimBreker materials!!
Read the report "Closed-loop Economy" from TU Delft and Leiden University.
- CO2 Tax: Currently this is extremely low. Multinationals, such as Shell and AKZO, state that this Tax should amount to at least €30.-/tonne CO2.
- Lower logistics costs due to the circular SmartCrusher system. An example: Transportation of new paving stones to the work site and of the old ones back to the factory to make new stones in the SmartCrusher.
‘SmartCrushing’ concrete rubble seems too good to be true. In spite of the fact that this technology has already been known for a few years and, especially in the past year, has been getting a lot of attention, there has never been any debate or discord about the SmartCrusher technology.
The 'SmartCrusher quarry 2020', in spite of its having been made widely available to experts, has never been under discussion either!
Conclusion : There is no alternative to the SmartCrusher for making the concrete cycle complete while serving the current manufacturing industry at the same time.
Sustainable Concrete Recycling - Closing the Loop
Making 1 kg of Portland cement from marl/limestone = 1 kg of CO2. (5 Billions tons in 2017)
For concrete construction, roughly 3x as much CO2 as all aircraft!
In all the concrete rubble is still roughly 50% new, reactive cement!
SmartCrushers free that new cement from concrete rubble and is immediately usable again.
The cement used (cement hydrate) is a CO2-free marl / limestone substitute for the production of new cement or
to be worked up as a binder or mixture improver.
SmartCrushing: Without marl / limestone quarry; dust-free and without harmful emissions new cement and concrete.
Sand and gravel from SmartCrushers is directly on location and ensures better concrete with less cement!
SmartCrushing reduces roughly 2.5 billion tons of CO2 per year.
Urban mining with SmartCrusher halves the cost of new concrete!
Worthless sludge by washing.
Large amounts of valuable sand and gravel with a lot of CO2.
Downgrading as road foundation.
Worthless crushed sand.
Concrete granulate in concrete requires more cement.