Sand from the Rocks for Concrete Production

Aggregates Processing

Sand from the Rocks for Concrete Production

New Type of Crushed Sand to replace natural Sand in Concrete Production
The availability of natural sand for concrete production is facing challenges, while the so-called waste stockpiles at aggregate crushing areas are causing problems for producers. This means that the industry has a huge need to solve this challenge by finding suitable technology for usable crushed sand production.
(ed. WoMaMarcel - 24/9/2015)
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Choosing the best Sand Production Process

It must, however, also be noted, that the new concepts described here is not a claim of inventing a “new type of bicycle” or a “miracle one button technology”. Is rather a concept that shows the unexplored possibilities of the technology that is available out from “Metso Minerals shelf” already today. The author will at all circumstances admit that the task of proving that a crushed sand product is worth a higher price (even if this is true) will not be a simple and easy task.

The main reasons for that are the aforementioned first historically unsuccessful attempts of using co-generated crushed fine material in concrete and second of all also because of legislative requirements that in many parts of the world can be discriminating towards the use of crushed sand, if it is tailor made for special performance in concrete and not a mime of an “ideal” natural sand. Then the aggregate producer can end up not only proving his clients that his product is worth the price, but in fact also proving to the authorities that it is allowed to be used for the projects that have to comply with the local standards.

Still every coarse aggregate production company has a wide range of choices of what to do with their surplus fines- dumping it in huge stock piles, trying to get rid of it at a very low or no price or try to make business out of it. If going for the last option, the next choice would then be choosing among the options of how sophisticated their crushed sand production should be. In some cases, the surplus fines can readily be of a quality that is suitable to be used in concrete in a blend with natural sand. However, this can also readily introduce some practical problems that need attention.

Such as that many concrete producers might not have an extra silo for the crushed sand available in their concrete plants and that if the fines content in the sand is extremely high, it would simply get stuck in the concrete producer’s aggregate silos at higher moisture content. The next step up the “ladder of crushed sand production” is probably installing a VSI, such as one of the Barmacs. That would allow considerably improving shape in the particle range down to and including the filler fractions. This would normally also have to be accompanied with a technique to reduce the fines content to an acceptable amount, such as a static air-classifier. Then if even higher quality of the sand is desired, the approach, described in this article, can be implemented, i.e. installing more than one air classifier and splitting the finest part of the sand in separate fractions.

Which is the best choice in each case, to the author’s opinion, will be rendered by the local market situation, however, to the same extent also by the fact, how much efforts in the long run the producer is willing to put forward in developing his product, not only on the technical side, but also actively working with technical support, sales and promotion. Or put it another way, crushed sand cannot be sold in the same way as for example 8/16 mm coarse aggregate, i.e. by sending a price offer and a declaration of determined physical/ alkali reactivity properties to a possible customer.

To the author’s perception, crushed sand needs much more technical kind of marketing and sales, in order to make it a success story. Those understanding the ready-mix concrete production business can compare this to selling concrete admixtures. Thus the author would advise one to be sure to have not only a skilled and professional team to deal with questions related aggregate but also concrete technology, and only then pursue the goal of developing a “different” aggregate production operation. This, is however, also true when analysing the market in which the producer operates. Thus not only such crucial factors as the availability of good natural sand or the overall price level of the aggregates should be considered.

Another important factor is in fact the technological level of the possible concrete clients. For example, Scandinavia in this case can be mentioned as a good example, since in general the largest concrete producers have experienced and most importantly highly academically educated concrete technology people. This means that there will be someone able to understand the possible benefits of the use of specially designed crushed fine aggregates. This also suggests, that companies having aggregate-concrete vertical integration have a larger potential of making money of high added value crushed sand production. This is since they can avoid the hard and time consuming work of getting the product into the market and also because they have the knowledge of concrete production technology readily available within the company.

The final remark would be that even though today crushed sand is still a developing business line among the minority of aggregate producers, one should keep in mind that without the risk and hard work it is doubtful possible coming to a great success, which in this case is a successful, more sustainable and profitable aggregate production in a long run.

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