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  White efflorescences on fences system

The next exhibition, the next - as always interesting - talk and another thing - the kind of simple, but not entirely. Great, well-known and respected producer of certain types of fencing, more items, and an equally big problem, due almost directly from the technology in which these elements are built. The problem concerns efflorescence on the ready, already flooded concrete fences system.

TThis type of masonry is most and most popular and increasingly used. There are many companies and many versions of how to build a wall. Typically, they are present in two forms:

  • ready-made forms, hollow, arranged like LEGO blocks
  • individual elements of different thickness (determined by the size and dimensions) joined together to special brackets, often dipped

They are usually produced "band", but its appearance and colors go natural stone, concrete coverings, decorative items. Because of the fairly wide range of colors they are more expensive than conventional precast, because of machine production cheaper than concrete imitations, decorative facade tiles etc. Their production is usually used cements the highest quality, often white, sometimes niskoalkalicznych. For this suitable filler, pigment and relevant chemicals. The result is a product with a relatively small amount of efflorescence. They occur usually on the elements to which the product is used ordinary gray cement, dyed even on dark or strong colors.

The quality of these components, resistance to stains due to the use of white cement as binder and what is the quality. The better, the less frequently the problem occurs, and if the cement is the best quality - basically eruptions is not all.

Unfortunately, despite such high quality products you can often hear that the fence already prepared these eruptions are the worst and they can not be nohow stop. If the silicone seal the merger, it will come out after some time on concrete; if the connection is not luted (as it was supposed to be in the original) - it will come out of them. Neither is nice or aesthetic, and fence looks downright hideous.

The problem is, how to build a fence. After placing each item on a given height arrives usually "pear" with concrete and open spaces are flooded to provide strength and rigidity. Sometimes the added reinforcement. Of course, the manufacturer recommends that the concrete had some class and word class is given when ordering. After flooding is applied to peaks in color, is deposited on the concrete (cement or sand) and the fence is finished. And here is the "crux"

The main problem is that they do not know on the basis of which is made of cement concrete. We do not know if the concrete has ordered in the "middle" type CEM I (exceptions), CEM II (most often) or CEM III (it happens) and what are the next symbols. For the record - usually the concrete mixes based popular class of cement CEM II AV or CEM II BV, in which the essential additive is fly ash, silica. Circulating cement are called ash cement, wherein the content of that ash can be up to 35% (for cement CEM II, other more).

Interestingly, despite the fact that the ashes like any other cement additive should meet certain standards, it is telling that every ash has the same properties despite met standards is thick abuse. Reading the article "Fly ash for road construction in light of the current standard requirements" by G. Roll and E. Slezak (Books ICiMB No. 9 Warsaw-Opole 2012), you can easily find the differences in the composition of the tested ashes, both of which samples meet the standard. SO3 content may be 2.49%, and perhaps 0.6%; free CaO content of 0.05% and 0.21%.

The composition of fly depends of course on what coal was burned and which type of boiler, by which - with or without the addition of so-called additive biomass ... In addition to this, of course, is a whole bunch of other compounds that make up this ash, and that are not reported in the study, because the behavior of concrete (scooping strength, resistance to frost etc.) have no effect, or their impact is small. Unfortunately there are no studies of whether and how they affect appearing on fences eruptions or salting out.

The obvious issue is fundamental: whether it is possible to eliminate any, discoloration and efflorescence. Because of what was already mentioned on plaster restoration, architectural concrete, the answer to that question is clear - be. It is a concrete made on the basis of white cement low-alkali.Using the cement we are confident physico-chemical composition, we are confident these or other properties, as well as two very important things:

  • its base is essentially the only clinker
  • alkali content of the influencing efflorescence is reduced to a minimum

These are two necessary and indispensable conditions to make the fence after pouring concrete will be just as nice and colorful as before.

Contrary to appearances, prepare on the construction of the concrete is not difficult. The composition is almost the same as ordinary concrete, the ingredients - apart from cement - the same. I write almost - because of their power and strength of cement can be slightly reduced (for those 10-15%) amount of cement added to the mix, and anyway her class and quality will be much higher than the "of purchasing." It is also important that the sand used in concrete was clean, no-frills type organic old leaves, debris (grains), coal and so on.

The main issue is the only answer to the question whether investing in fencing (construction elements: blocks, panels, plates) should also save on the concrete, which is poured in? Whether such savings worth it? The answer is clear and is no.

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