Everything about white cement

  Restoration plasters

In theory these are special plasters used in the restoration and maintenance of the facade internal or external, in various types of plaster, which meets certain conditions fully protect against so-called. wysoleniami, or the appearance of garyish raids or efflorescence. All the restoration plasters, in theory at least, to make the problem disappear. Is that the reality?

Efflorescences - this is the problem of cement and its composition, but not with lime, as is generally believed. Just look at the old lime plaster, made exclusively with lime, to see that such problems do not occur. Lime fully for at least two very important roles:

  • plasticizer,
  • fungicidal and bactericidal agent (because even a half-century ago whitewashed outbuildings)

As already I mentioned, salting out and the problems associated with air raids are related to cement, and more specifically the content of the alkali. European standards defining the quality of the cement does not say whether or not precisely indicate the obligation to study the amount of alkali in the cement samples sent. This means that it really about the fact that the type of cement is low alkali inform (in Europe) letters LA in the letter designation of a type of cement.(Sometimes the manufacturer nothing about writing, and information on the amount of alkali is contained technical parameters of cement)

In various tenders and specifications can read about that prerequisite is to use the full system refinishing, whose individual parts are different, in principle, merely a degree of compressive strength and adhesion to the substrate, all the talk about three important issues:

  • vapor permeability at level W0
  • have a special small air pores to "imprison" efflorences
  • alkali content is approx. 0.02%

Each mineral plaster - regardless of whether it is plain, restoration or any other - made up of various amounts of cement, lime and filler (eg. Sand) of the desired thickness. Different amounts of cement and lime determine different classes of strength plaster (or cement-lime, since the composition is very similar to the plaster and subject to the same qualifications and determinants), and sand (or other filler) - it is only the thickness.

Vapor permeability at W0 is usually any mineral plaster unmodified to "seal", slow down or block the passage therethrough of moisture. This is simply the charm ...

Pores,designed to imprisonment of efflorescence, in turn aerators of various kinds, or because of the price and also plasticizers having this function in addition to that characteristic - that is, reducing the quantity of water to obtain the desired properties.

The last information about the alkali content is the most important, because it means that we really to produce such plaster is used simply cement niskoalkaliczny. The numbers, which I will give below, you can very easily derive directly from the warehouses and technical data given on the websites of manufacturers blends restoration. The composition of the plaster is as follows: about 1/1/8, the mortar is white, which means the use of white cement. Assuming that the cement has niskoalkaliczny alkali content max. 0.4% "purely" in white cement, in this type of mortar approx. 1/10 of that, or 0.04% (or less, when the alkali level in cement is lower).

Additional protection may be the use of so-called. lime waypoint, in which the composition of the routes itself as security for the plaster against efflorescence.

Interestingly, many fencing contractors on the basis of natural stone, bricks hand molded etc. that make up the outer part of the applied mortar based on white cement, lime and sand - depending on the color of the grout, which is to be - white or gray. The center flooded with concrete to most ordinary cement, which can be purchased at any desired composition of the building - which is usually the cheapest cement. One of the many activities performed is called "obsequiousness" or applying on top of a stone wall - normally with stone sticky white cement 52.5 class and sand in the ratio 1: 3 or 1: 3.5.

The final part is priming, which protect the stone (!), Usually sandstone or limestone by weather conditions. This means that the mortar mixed "on site" based on white cement, lime and sand could be successfully used in all kinds of renovation work inside and outside of historic buildings, if not as a final finish, at least as a primer, Fillers, the final plaster or layer, which aims to "straighten out" the wall. Its properties are comparable to "plaster restoration," mixing in place allows you to obtain the desired strength properties and other "real-time" - the main advantage - price.

In Poland prices plaster restoration start at approx. PLN 30 per bag, but usually amounts to approx. PLN 40, sometimes reaching 60 and over PLN. Assuming that the price of one sack and 25 kg is 30 PLN (this is probably the cheapest plaster referred to as the restoration of the backing), the cost of 1 ton is 1200 PLN, the price per bag of 50 PLN - already 2000 PLN. Meanwhile, the cost of plaster (white!) In homemade is a regular lime is:

  • for the composition 1/1/5 (assuming the price of a bag of cement 27 PLN, a bag of lime waypoint 45 PLN, the usual bag of lime and PLN 11, ton of sand with delivery PLN 60) - less than 260 PLN
  • or the composition 1/1/5 - for lime waypoint - assuming as before - less than 450 PLN.

With more sand difference is even bigger. This means huge savings ranging from three to more than ten times the cost of materials in the renovation of historical monuments in the situation, when used tens or hundreds of tons of materials. The outer layer of plaster, of course, should be made of plaster refinishing, due to the thickness of the filler and the necessary smooth walls. Just consider that a small house hundreds of square meters of interior walls on which they are expeditions designed to align them having a fairly large thickness, to find out how to better manage money, using the expertise and capabilities that give us cements low alkaline, and ordinary knowledge of technology plaster.

Interestingly, a few or a dozen years ago, used just such a mortar prepared on site - on the spot, using the highest quality materials available on the market. Determined by this method as traditional. It was not disputed by both conservation authorities and by the performers themselves. Even today, he not lost it on the news, has not lost its characteristics and advantages, ba - still is comparable with pre-plaster, which today are in use. Furthermore - knowledge of ingredients as used means that the message which cement is used, it is known lime, it is known what is the quality plaster. Emerging information about "comfort" plasters ready, available as dry mixes in bags are for the most part only a partial truth. Either way you need them rozrobiŠ with water to make them ready for use - which means the risk of adding too much of it or too little, with all its consequences. More specifically studying and evaluating the finished plaster sometimes you will come across information, which call into question the accuracy of the recipes blends - that entries talking about content "in terms of clinker 7-9%."

For that reason alone I propose to consider when renovating the ability to perform parts of plaster restoration traditional method.

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