Everything about white cement

  The brick

Increasingly popular and increasingly fashionable after years of absence is a brick - as far as possible, of course, hand-formed, as close as possible to those who years ago experienced. Unfortunately, getting closer and the similarity is in too many cases, merely external.

Historically, the process of production of bricks went years on, even from a dozen to twenty or more years. In broad outline, looked like it. From the reservoir dug clay, then cleaned it with heavy pollution, water was added, parted into smaller parts, and again elected pollution. Then the clay was decomposed - this process consisted in the fact that the excavated material was subject to the influence of external conditions. The process according to eighteenth-century studies should last at least 7 years, and at the turn of the nineteenth and twentieth recommended that it should be at least one season, that is taking into account the fact that it came two winters - it was really a half years. By the way, the development of eighteenth-century mentions that earlier courts punish prison if brickmakers (that is, the people behind this operation responsible) decomposed clay less as five years ...

Such a long time to prepare the material allowed him a get a very good raw material for the production of bricks. Then was added to the already pure clay, stirred and loaded into molds. Of course, the same drying process has been slow on the "open air", most under the roof to the rains do not disrupt the process. After all this was followed by firing, each (!) part of clay was treated individually - because its composition differed slightly from what was before and what came later. This behavior allowed to get a brick desired parameters or so, on what was to order

After the firing process already ready brick "recovering from" well under shelters, under the most natural, and the client receive the bricks dry, the production process in the worst case lasted from the dig clay from a deposit of at least 12-13 years, and could even over three decades.

The quality of the prepared brick amazes even today. Renovation of a large church. Say to the south of the country, the church with the military heritage, and with the past. On the question of how the matter is - brick until it sounds, basically there is no problem at all with it. Not durable joints. Such a resounding brick had two important features, almost "ex officio" - had high strength and was basically non-absorbable

At that time, the mortar was almost exclusively limestone - which meant that the component was sand and lime in a variety of existing forms and modifications. The mortar was modified by natural resources. The reason for this is not stuck in the fact that lime mortar is weak but because of that, quite slowly ran the binding process. One of the simplest modification was added to the slaked lime a animals carcass, allowed that, after a certain period, a casein adhesive, which accelerate the hardening of same on the occasion of making a stronger and waterproof mortar. A modification of this method was to add eggs, shells and so on.

Eighteenth-century knowledge allowed based on the known ingredients to create the mortar, which was connected in about thirty minutes to an hour (there are differences depending on its composition)

At the end of a clear and obvious thing was the knowledge of how to use different types of brick - a brick which give an absorbable, and where on the contrary. To conclude this brief introduction-lecture can say that in the past proffesionals were able:

  • create different types of bricks
  • create a fugue, which was strong and at the same time weaker than brick

At present, the problem is with everything.

The bricks are essentially divided in respect of its water absorption (i.e., how much water is absorbed in the self brick) and the strength (which can withstand pressure). Generally, both of these values are related to opposite - that is, the higher the water absorption, the smaller the resistance.

In the first case, a brick is divided into high average and low absorbable. The second will be indicated by markings, ex. M10, M15 - which simply means compression strength expressed in MPa.

In past years, no reasonable foreman highly absorbable brick a low strength would not give to the fence, but with relish applied to the kitchen or bathroom on the walls or interior trim. Its ability to absorb moisture can absorb the excess of space, which, because of the use to have her "ex officio" excess. On the other hand, they tend to be continuously heated or heated, allowing the bricks of that moisture evaporate - disappear, that does not affect the same brick and its behavior.

Low absorbable brick - here you can guess fences, walls, even the foundation - a small absorption eliminates almost completely the possibility of entering the water, even when the environment is extremely unfavorable (wet terrain, rising from the ground). Such places are generally unheated or even this small amount of water that enters is removed much longer than in the first embodiment.

At the moment, few people (I do not want to write no one) does not return to such "details" of attention. Brick is a brick, piece counts, as long as the declared strength somehow gave hope that the wall can withstand. Of course, this results in cracking walls, breakdowns, if only because of the freezing of bricks.

Another equally important issue is that as a matter of fact none production process from extraction of brick clay brick for dispatch / sales does not take years, but rather months and is shorter than longer. This means that the amount of impurities, which is in the brick is - let's call it euphemistically - much larger than before. They can also appear during laying or next winter (marl, organic pollutants etc.), whether as stains, whether as cracking bricks.

For the buyer or investor, this means that it really is the purpose and the place where it will be used brick sets of without any doubt its characteristics, and the need for high quality is more important than a few pennies, you can tear off the purchase of inferior material. Rind in such cases does not show the worth of effort.

Another issue is the mortar on which a brick is masoned, and more precisely its strength (hardness) and its composition.

The strength of the mortar can not be higher than the strength of the brick. The word strength here means precisely its absorption. This is a valid reason. If the mortar were any pollution or worse, the materials used for its creation were of inferior quality, it should not be under the influence of moisture or adverse weather conditions pass "on a brick." As would happen if the tightness (measured aeration, or the amount of air in the mixture) was less than that, which has a brick (here is a measure of absorption and / or strength). It's on it very easily can occur raid, even white or light in color, while the joint will remain clean.

Why do these problems was not before? This resulted directly from the composition of the mortar - at first they were strictly limestone, then lime-cement, but the quality a lime (slaked then) or cement (see related article) was diametrically different. Besides, the then contractor not only have the knowledge of this and mortar mingled on the site is used and the quality of the bricks was significantly higher.

At present, there are essentially two options mortar mixed "on site". One of them includes in its composition slaked lime (or hydrated), in addition to cement (very important and it is important that it was a cement-type IR - without additives and best low alkaline type, either white or gray - depending on the color of the grout) and filler . In this case, to reduce the resistance of mortar to fit the imported brick, just slightly increase the amount of filler (sand), and reduce the amount of lime or cement. Usually brick imported in one batch should have similar properties.

In the second, when the lime is replaced chemistry - the easiest way is to increase the amount of filler, for chemicals (plasticizer, etc.) is usually added in the amount of cement.

Very important in the mortar mixed on site, in a situation when we do not fully believe that the quality of the bricks had brought to us by the manufacturer corresponds to what is in the package leaflet to add chemical agents, so that the water will have another barrier absorbency. This means nothing less than just a behavior similar to the detergents used as liquid detergents. They modify the properties of water in such a way that no problem in lukewarm or cool water can wash the grease, which "pure" water can not or is this a very big problem. The water may not be entirely or almost entirely absorbed by the brick - it must be in the mortar to cement could safely bind.

This has its advantages, as mortar or dries at a time along the entire length of the wall, there is, therefore, no problems with tint (for a mortar were dyed - since the drying time defines both the power and color depth), "absorbent" bricks will not drink excessive water, and will not then cause any problems during the impregnation. In extreme cases, when the brick absorbs water, mortar can never tie or do it very poorly.

They are available on the market, of course, ready mortars, but to apply them, you really need to read the instructions, not only with descriptions of application, but also the safety data sheet, where are described their precise parameters, including strength. Of course, not recommended or even prohibited the use of mortar is not intended for the type of bricks. If the brick is highly absorbable, then the mortar must be used for its masonry.

At the market you can find three large groups of mortars, the distinction between the first two corresponding to the amount of water that must be used to ensure that suitable for use in the final determinant is the use of trass in its composition.

The first group is ready mortar based on cement, lime and filler. Their composition is similar to the variation 1: 1: 8.5 (cement / lime / filler). The amount of water that manufacturers recommend that approx. 5.5-6 l per 25 kg. It is a simple mortar, usually made of cement-based ash (probably CEM II AV or BV), and as such has all the disadvantages that result from the use of this type of binding material

An indicator of additional chemicals may be time, after which is not suitable for use. If it is less than an hour you suspect that has been applied accelerator binding. Data sheet of this type cements start setting time, ie the time when the cement starts to set the tie of rather not less than 90-100 minutes, and sometimes even reaches more than 120. Their quality is euphemistically call it different, the only advantage - the price, but it should be much higher than he to make mortar for building, mixed use of the best ingredients on the market - including white cement.

The second - a mortar modified. Its symptom is that the amount of water is determined almost drugstore accuracy - usually approx. 4-4.5 l + - 0,2-0,25 l. In addition to the composition of cement (usually about several percent, and it is possible that almost twenty), "the remains" of lime (probably within a maximum of 2-2.5%), is included chemistry, which aims to aeration of mortar, as well as one that has to somehow "make" slaked lime (or compound similar properties), without mentioning. Responsible for it is usually a supplement based on limestone and two strong additions of chemical type - one modifying compounds based on calcium, the second transforming the latter, after the first part of the reaction, something like slaked lime. The amount of these last two forms is typically in the range 1: 5 to 1: 7 (depending on which and from which the quality level is used). Because of the amount of chemical used and its power, the amount of water must be strictly dosage that is not found the chemistry “eat each other” they become unpredictable behavior and mortar will have any properties, but not such as desired. Of course, in theory, should be used as the purest cement to stability reaction was as high as possible.

Unfortunately, often unofficial and informal conversations people dealing with the chemistry of concrete admit that the big manufacturers use the cheapest materials and then the parameters are drastically increased by chemistry.

Interestingly a similar mortar can be very easily and very quickly on site, using as a base cement pure portland CEM IR, "tap water" sand of the desired grain size and chemistry available respectively in good quality shop construction and ordinary store with basic articles used at home. This mix because of the purity of the most important ingredient - cement - besides the price is indisputable advantage - basically do not have the right to appear discolored, if only the same joint will be weaker than the masonry brick.

The last group are the mortar mortar with trass. Trass is a material of volcanic origin, which "makes air bubbles", while blocking the exit of efflorescence. Once again, savings of cement causes the mortars have very expensive herein only to limit the amount and the occurrence of efflorescence. The answer “why” gives us why the SDS in section “hazard” - mortar contains portland cement dust and ash. Again, everything is clear.

This is what you can safely achieve on the site, using the highest quality ingredients and mixing them yourself, at the Great Producers is only a "limited". Additionally, you can meet with publications that speak of the fact that lesions result from the improper use of mortars in the wrong place at the wrong conditions. Yes - it was the direct cause of the fact that the efflorescence appeared on the brick, and not because they were not there. They appeared in such an amount as many cement containing ash. The ash that is obtained by burning "charge" in the power plant, harder for electrostatic and sold. Its composition depends on everything: electrostatic precipitators, a producer of coal, coal grade, even the type of charge, but how this "black gold" was even used (ie. using biomass).

Talking with contractors "mixing yourself mortar on the construction" you can easily find out that in many cases the use of the simplest mortar very good ingredients already provides the desired effect, and can be found easily and those who gently modifying its composition means almost household reach without difficulty what the great are not able to guarantee despite their - let's call it mildly - effort.

Interestingly old walls and fences, even from the beginning of the twentieth century in brick masonry, even on cement and lime have no problems with the eruptions, sometimes with the strength of the joints, very special with the brick. The explanation is simple: at the time was of excellent quality cement and / or slaked lime, known household ways to change the properties of mortar, grout was weaker than bricks, and the latter very high quality. Maybe it's time to begin to adhere to those rules, which use the best cements (pure without additives, type IR, low alkaline), lime or simple chemistry and know where and how a brick can be used?

The final stage of the construction of the fence is to impregnate. In some simplification it is to prevent the destruction of bricks, to facilitate its cleaning, and protect it from excessive moisture. In theory, everything is as it should be - brick by such protection should not be affected by unfavorable external conditions, should be easily removed from its various impurities, and the long rains or moisture from reaching the basement will not be terrible for her

In practice, whether it come true and to what extent, depends on:

  • the type of brick and its condition
  • application methods
  • selection center, which will protect the fence

This is what has been used brick, determines and enforces even a kind of impregnation. Do not be lured by descriptions such as "suitable for any kind of wall, is suitable for every type of brick." Permeability brick also means how much, where and how deeply penetrates impregnation. Bad decision will result in the fact that certain portions of the bricks are impregnated, others do not.

It should be obvious by the fact that before trying to impose himself inside a brick should be dry and not only from the top, but inside the wall. One of the important roles that it has to give us, resistance to water penetration into the brick. Essentially, this means difficulties before exiting the water with the same wall. When the brick is wet, simply stopping the water in brick, which in the nearest cold winter may lead to burst and damage the brick fragment or the whole fence. Brick by simply freezing. The more absorbable brick, the risk is higher.

The preferred method of application is similar to the gun used to apply the paint, ex. a car. Proper application of the recommended measure for the type and the type of brick should result in a reliable security wall.

One would like to ask you to impregnate - after all, the old houses are enough to drive to Silesia, although brick is black with dirt recessed on it, and fugue has the best years behind him? The answer is simple - once otherwise produced brick, perfectly they knew how and where to apply it, were well known absorption minimum parameters required for the foundations, external walls, partitions and finally the kitchen and bathrooms.

The same was with mortars - mixed on the spot at the construction site, they were adjusted each time the "here and now" to conditions that dictated brick and place where erected house.

Unfortunately, today, in principle, it is already gone, trying too often to replace a sound knowledge and perfection of material ready mortars, interestingly mixed with the poor quality of ingredients, the parameters of which are pulled too much chemistry. Unfortunately, the quality can not be a stretch, since it stems directly from the fact that the ingredients are used to create the mortar. If the site we use the highest available from the shelf, then the mortar we created, even if it is not signed and stamped logo Great Manufacturer. The cost of its production will be for orders of magnitude smaller than that which can be found in the shop.

© 2012-2016    whitecement.ch
Valid XHTML 1.0 StrictValid CSS 3