Everything about white cement

  Patent or "patent"


Someone a few years ago said that the Internet is everything - from junk to the diamonds, someone else has created a tool that allows, or is it better to define trying to weed out one from the other and ironically called them "uncle google". In another place - the same Internet has enabled the creation of giant platforms, or rather sites where you meet people from all over the world to admire what they do, talk, ask. The more heads, the better, the more questions the more answers ...

One day, "Uncle" threw issued with one at the question, as one of any number of text from the patent. Polish, not much different from what is offered by a large group of manufacturers, developed a few years ago for renovation plasters. Perhaps it is already used to produce on the basis of one or several types of plaster, I do not know. Composition given - of course approximate, but allows one to figure out how it was created, what was the idea behind its authors.

On the same day, maybe a little earlier, on one of the sites, discussion started, in English, about what plasters to be used for restoration of monuments, it was just about some Victorian houses, built of brick, with stone motifs. In a word "in the United Kingdom" classic construction. Any attempt to use a different type of plaster, than the original, even if this was purely limestone, were criticized. The company even boasted that if the plaster is lime that others do not use. Because it would be like sacrilege. Breaking the rules.


There are basically two extremes almost to the limit approaches - how to restore the buildings.

The old building is almost without exception brick, still hand-formed, it happens that since the nineteenth century by machines and stone - mined in quarries in the near vicinity. Research brick used originally in the north Polish, also by the Teutonic Knights and their successors allow the judge that it has a fairly similar parameters. Strength class of about 7.5 to a maximum of 9.5 MPa, water absorption average of about 10-12 percent, although other bit more extreme values ??will go up as well. Apparently all is well. Problems arise, however, more or less immediately. Historians dealing with a particular apartment building, they know only large rearrangements, which involved such measures, the size and cost were significant enough to have their information included in the annals of the books. Smaller passed unnoticed. Any such change meant the use of another brick with slightly different parameters. Once they can be worse once - better. Important, however, is one issue that until the middle or even the end of the nineteenth century it was not a problem because, as plasters were almost without exception limestone. Absorbent, fast-paced rising damp, even if she does not destroy their moisture, even if the bonding process was conducted in her presence. Often mentioned was also the lime cement plaster were in common use even in the 60's and 70 of these, especially where the possibility of the investor was not unlimited. Cement is often served them only as a hydraulic binding material, allowing escape from a bit more complicated configurations mortars pure limestone. He facilitated the work. Confronting these messages with substantial renovation plasters recommended for bricks, which gives Domasławski professor, is the strength of the most approx. 4.5 - 5.5 MPa, water absorption over 10 percent, and the rate of rising moisture to a height of 5 cm in less than 60 - 70 minutes, it leads to the conclusion that according to these standards essential, most of them were or are simply renovating.


Patent is fairly accurate, you can be read, however, that the mortar is too strong, that is those of about 5 MPa, on the other hand, is characterized by a limitation of salting-out, relatively low capillary. Such things are achieved through the use of usually very small fraction is sometimes hydraulic (dust), and a strong aeration, which allows you to create a place where they gathered salts (eg. Calcium). The information provided by the manufacturer can be found sometimes the information that m2 mortar with a specific thickness allows you to draw a given amount of water. This information does not say much, because it really should be given more information that needs to be the difference in hardness, or more precisely at a rate of rising damp in both communities, what is the difference in water absorption, that such a condition was met and the results credible.

The sake of accuracy and reminders. According to the old rules of art the most hard nasiąkliwym least, minimum pull-up moisture material should be, in our case - brick (basically parameters of approx. 7.5 - 9 MPa, water absorption ok.10-12%, respectively, reaching approx. 8% and 14 % in extreme cases, the pace of rising damp, we do not know, but probably less than 90 minutes), mortar joining the bricks should be weaker, more absorbable and more rapidly pulling moisture, the layers of plaster (fillers, overhead, finishing) respectively slightly weaker. Again, the theory says that we should know the extreme parameters of building materials throughout, continuing the example, the building, as well as knowledge of where and what type of mortar was used. Tests if they are conducted in several adopted by conservationists as the most representative places and on their basis conclusions are drawn.

Keep in mind also that the current brick, especially the hand-molded, used in such buildings to complement the buildings, reconstruction of walls etc, are much lower quality than the originals, and many a one absorption is close to 20 percent, and the water stretches almost as much like a sponge. This means that in fact almost never, almost in any case we can not exactly answer the question of where the brick is what, at which point what exactly mortar was used. You can be answered on the basis of the construction when the building of itself and using the knowledge, answer the question, what then was typical mortar. Limestone, lime - cement or cement - limestone.


Several parameters described in the patent to repair plaster: water absorption up to 10%, the low pace of rising damp, shows that despite the fact that it carries the name of the Restoration, it may be that will eventually do more harm than good. This happens for several reasons:

  • we do not know exactly what parameters a brick used to build "our" house and the cradle, saying that a typical brick is approx. 10-12%, does not allow us to determine whether any part of no other parameters
  • we do not know exactly what the parameters are all the grout / mortar used for masonry and created at different times. We only know that if it was not carried out before the renovation, but are original, done it "in accordance with the contemporary art of building"
  • we do not know exactly all the changes and modifications that were made, sometimes the only example. The chemical (use of a strong and aggressive acid) allows you to discover exactly where and what type of grout (limestone or lime - cement) was used. This is because it reacts differently to one, otherwise the second fugue.
  • standards for restoration plasters, as accurate, especially those based on WTA is a fairly new idea and a fairly new invention, which does not take into account local "version" and "compunds" plaster adapted to the building material and its characteristics which was used in various areas at different times.

This alone shows that the use of ready-made, even patented plaster, which passed all the current research, testing and evaluation results are authorizing them to use in the restoration of monuments should be treated with great caution. It may be that used on one building, which went through several minor repairs or modifications to the exterior walls will behave in different ways. On one wall will be perfect, while the next two are the brick will be doing so. chaff. It will from that brick less permeable, harder, which would mean that the moisture rather than go outside will be "sitting" in the middle. Other rules of the trade which existed decades earlier, during the construction of the building, could make that moisture faster coming out of one wall, a brick was used with slightly different parameters and a slightly different type of plaster.


It is for these reasons, many conservationists working with European companies or supervisors data robots, prefers plaster from the era when the building was built. They then assured that no matter what is the brick wall that has been carried out repairs, and finally, no matter how good, and sometimes how weak is now produced brick used to supplement the topics and cavities plaster used will be adequate and will fulfill its role. This attitude, however, requires a very important thing - it is an in-depth knowledge of the old rules, principles, compositions and methods for the formation of mortars and plasters, in such a way to be able to evaluate on an ongoing basis its composition and, although roughly parameters. For such people, centers offering expertise and extensive knowledge offering the use of cement, and often obtain hydrauliczności through the addition of cement in the case when the original mortar was strictly limestone is at least inappropriate. Often, they even praise that during the entire renovation of the powerful house, a castle or palace is not land or grams (or rather ounces) with the addition of cement mortar.

Unfortunately, in several countries (f. ex. in Poland) this knowledge is too often not known, treated with neglect. After all, they are ready mortar renovations, which the manufacturer (here: it does not matter whether they are patented or not) ensure that it is suitable for highly absorbent or low-absorbent brick is suitable like no other, and in general ... In the absence of really precise knowledge (that is, in principle, almost every brick, grout etc) reminds a little teasing a lion. The risk of large pleasure questionable. Interestingly, there are the old building development enabling learn what were the mortar stores, which is characterized by what were their performance, enabling trace is how to change, but unfortunately they are not familiar to most people involved in maintenance.

Yes, talking really old professionals of maintenance, remembering the time before tens of years (eg. In Poland is only one college fair learning about how to make mortar having the appropriate parameters for what will meet "on site") you can see that there are some fairly simple ways to not change the principle parameters of blends, but the use of the properties that we cement (hydraulic, the pace of bond strength). Unfortunately, knowing all too often goes to the past.


To sum up - the method mortars suitable for a given period, or the use of mortars appropriate type (eg. pure limestone, if we know only that the original was based on the binder) can basically avoid any problems which so far can not give yourself the end of the council modern recipes based on cement, sand, dust, slag and large amounts of chemicals. However, they require reliable knowledge, so rare among some conservationists/p>

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