Everything about white cement

  The ready-made mortars and plasters, or how to read what the producers write

If you want to buy the most suitable plaster or the best mortar for our needs we meet in the shop with delectable Mr. or Mrs., which throw in our face a lot of wise words, very professional phrases ending usually by saying that our plaster, this here for me is most ideal for what happened to need. Unfortunately, this is only in exceptional cases.

Even 30-40 years ago, the matter was simple: cement, slaked lime, filler - usually fine sand dug, old foremen were looking for even such a small clay content. The composition also was not a military secret. Depending on the quality of cement, lime quality or destination of the model was around 1: 1-3: 6-10 (in amounts by weight - respectively, cement, slaked lime - understood as lime putty, later lime and then, at the end of this sand). Relations changed depending on the destination - the others were on the plaster, the other for the mortar to an ordinary wall, still others to make bricks. Lime putty, as already mentioned, gave plasticity and "fluffied" (ie aerated mortar), filler - did the same mass.

Even today people masoning natural stone, (usually sandstone or limestone), brick rarely if professionals are buying the mortar - usually mix it on site, reducing even the amount of lime and sand if necessary, approaching the composition of the concrete, as it usually is a wall made on the basis of this stone is the most powerful piece of fence, sometimes reinforced in places even reinforcement.

Experts "working" in the brick will weaker and more aerated mortar, which means that in one way or another must make in some way occurred in one slaked lime, and a filler. From the same reason, the amount of filler is relatively large.

No matter where we look, no matter where we look, where reference is made plaster or mortar type cement – limestone (c/l) in one way or another, knowing some basic rules and principles easily find the part that we need. Short reminder:

  • cement - should be no additives, low alkalia (LA) - is responsible for binding the pace and strength that - this is important - there must be always and everywhere the highest; the strength or power of mortar especially in plaster external and / or internal forces somewhat thickness of one layer
  • slaked lime - is responsible for plasticity and fluffied, that is, so that air bubbles are formed in the mortar (air pores), and which in turn is a guarantee for better or worse frost resistance; at these pores is the place to accumulate ice forming of moisture, which may be in plaster; a separate feature of the lime is that it works biocidally
  • sand - filler, which gives the mortar mass - the less the ratio of cement - the stronger the mortar; the rule is that the plasters must have a lot of fines

At the present time certain desirable properties can be enhanced plasticizers (reduce the amount of mixing water in order to obtain a plastic mortar / plaster, which is beneficial to the lack of cracks when it is powerful - just slower linked), or agents acting as detergents - they, in turn, associated with suitable plasticizers allow the "artificial" or rather "chemical" way to get the dough lime in the mortar during the mixing.

The amount of water, which requires approx. 25 kg of plaster or mortar without any additives type of plasticizer is usually approx. 7 liters. About - since the exact amount depends on the composition, moisture content and thickness of the specific type of filler and cement. It may well be, and almost 8 liters and a little above 6.

These are some basic knowledge will allow us to understand exactly what is in this great mortars and plasters proposed to us by the Great Producers as usual as Big Money. Due to the fact that unfortunately the easteuropean markets in many cases is considered "neglect" by the great, you should also benefit from information that are placed on the market for example. German.

For us, the most important are three documents that the manufacturer has, or at least should post. In any case, they are not confidential, and should be made available on request of the buyer.

1. Description - this is the manufacturer publishes a few words about what we want to sell. This is usually eg. a kind of plaster (lime, cement-lime), seasonings (eg. for the low water absorptive bricks). Sometimes it gives a few words on the basis of what in theory is made, with stirring used for our needs the goods. Sometimes, there misread some remarks about the composition (which is - eg. trass, or did not have - even lime). One answer: a few usually the most general information.

2. Technical Data - sometimes "how to apply" - here is given the brand and type with a detailed description. Normally shall also some of the most common parameters of the same. For us, the most important are the four that must be given:

a. Density, bulk weight - expressed in g/cm3 or kg/m 3 - after it without any problem we will know whether the plaster used "normal" filler or a lighter substitute (perlite, expanded clay). The latter make it instead of well above 1.5 t/m3 weighs usually slightly above tones, and in rare cases - even lower tones. The density of water is 1.0 t/m3. Keramzyties or perlites are usually slightly less durable than the traditional "sands". No problem, this information is to be found also on german counterparts.

b. . The thickness of the aggregate - in the name should be given, if the mortar is coarse or not. The coarseness means that the filler is of grain size is larger than 2.0 mm, typically to 4.0 mm. Grained have given to 2.0 mm, but you can be almost sure that as a matter of fact the maximum thickness and grain size of the sand is slightly more than half of its size - up to 1.2-1.5 mm, with a large share fraction below 0, 8 mm.

Comparing the data contained on the cards available in f.ex in Poland and in Germany can easily notice that in its west neighbors, no one lies with a thickness of grain and poses no trouble finding in them the same product, which is described in Poland as to 4.0 mm, in Germany as to 2.0 mm, or when it is in Poland to. 2.0 mm, in German to 0.8 mm. You can ask this question advisors - I wonder what the response will fall. I heard that just three months ago has changed there (that is, on the Rhines) recipe. Perhaps this is due to the fact that there are slightly different requirements defining what is to be described and is used with complete ruthlessness.

Grain thickness is determined in millimeters. The circulation of the word "flour", "five", "eight", "ten", “voussoir” etc. usually determine the upper limit of the grain in mm. Meal, usually within 2.0 mm (although it may sometimes be slightly less), and then successively from 2.0 to 5.0 mm, from 5.0 mm to 8.0 mm etc. Voussoir include scale of 0 to 63 mm . Fractions obtained in the process of milling or crushing and grinding the excavated rock, which is delivered on the next screen of data mesh sizes - these millimeters and what they "pass" is just such a rock treated as a filling. If the meshes of a square shape and one side is 2.0 mm, it is really grains which pass through them, is slightly greater granularity - approx. 2.8 mm, and all is over 2.0 mm is termed oversize . Perhaps this is an excuse or reason that it is sometimes distorting granulation ...

c. Typically, cement-type IR or without additives, is defined as the beginning of the setting time of approx. 90 to 120 minutes, the end of the setting time of between 180 and 240. This means that the binding usually begins after approx. 90 minutes, which means that the this time, mortar or plaster is unfit for use. Cement additives (such as ash et al.), Rarely have the time shorter, usually even a little longer. To us, this means that in principle no mortar should not be potlife ready less than 60 minutes, and sometimes even more. Interestingly, the vast majority of plasticizers are delays the onset of this process, because water is simply physically or less, although it is sufficient to yield a blend.If it is checked that the mortar is unsuitable for use in running (mixed with water) after 30 minutes, it can be almost assured that the addition of a plasticizer has been added there chemicals intended to accelerate processes that delays plasticizer.

d. The amount of water based on the bag. Here you can find big differences in the data contained on the polish and german pages, even approx. 0.5 liters to 3 liters. On the German side of this important issue it is given usually much more accurately than for ex. in Polish

A typical mortar or plaster (cement-lime), even with small amounts of plasticizer, must accept those about 5.5-6 liters of water, so you can specify it as it passed use. The less water, the more chemicals are contained in the mortar, typically in the form of a powder. These are usually (or all or part):

  • - strong plasticizers - acting also as mentioned retardants beginning of setting time - limit the amount of necessary water needed to mortar was plastic and safe to use
  • accelerators setting time, reducing the plasticizing effects of various substances
  • - aerators - except that they are intended to replace and slaked lime to produce pores in mortar / plaster, is also typically nearly influencing the "toughness" blend and the plasticized a bit
  • chemicals acting as a detergent - compounds affecting the calcium contained either in admixture or in water - if they are in the finished product, it is nearly their number is associated with an amount of a plasticizer, and their ratio is very well defined
  • if nothing is missing, biocides - providing resistance to algae and other filth, which is replacing in that role lime

Usually meets two versions of the composition or the chemistry of acting as a detergent or a biocide instead.

In the first case the amount of water is reduced by about half, and this amount depending on the composition, granulating and cement is approx. 3 liters, with a possible error of + - 0.2 liter. As a matter of fact under construction is accurate, if not apothecary, it's very large. This is a simple reason - a large number of chemicals, including strong plastifying limits the amount of mixing water required for this. to blend had the desired properties, and the relation of the other two agents from each other and the chemical make small the amount of measurement error (about cup) makes the mortar is unfit for use.

In the second case, when the biocide is, the water is a little more - approx. 4-4.5 liter, and a measurement error is larger. Sometimes referred to as 0.5 l per 25 kg.

Unfortunately, you can also encounter situations where differences in the data contained on the pages of Polish and German are considerable. In one of the cases in Polish about this amount was 2-3 liters per 25 kg - which is impossible, and the German after conversion using a different amount of weight (probably 40 kg per 25 kg) was "about" 3.4 l - which the value much more real and reliable.

There are only a few of these details will allow the assignment of several "difficult" questions and forces the necessity of receiving reliable answers, as well as understanding what is really the so-called wise and scientific words that convey our technical advisors.

3. The most important document for us is the safety data sheet (SDS or MSDS).Here, too, it is worth to study f.ex. polish (middle Europe country) and german versions. Sometimes considerable differences in the information contained.

Safety Data Sheet (more specifically, hazardous material) contains all the information which the person having contact with it may need: from the mode of transport to storage, the risks associated with the moisture risks in critical conditions, are given to this even among What are the ingredients in the mix, those that are active during operation and approximately that which has been created. For us, the most important are three pieces of information.

a. Identification of the mixture / product description - served in one of the starting points. In polish conditions, it is usually a description of the type: ready mix cement and lime-based cement, lime and enriching ingredients. The german side describe it more accurately, exchanging usually quite accurately, what is in any such mixture. So you can read about Portland cement, a calcium (interestingly both "building" and "extinguished"), meal of marble or quartz sand. The latter are normally referred to as high-grade. They are, moreover, usually used as a "typical" fillers, especially because of the popularity and the possibility of obtaining a very specific granularity required by the manufacturer. This section describes the finished (!), Already mixed and prepared for use of the product. For us it is very important.

b. Composition / information on ingredients - usually given in tabular form containing hazardous components. As we approached them, they include both the cement and lime, they must be given. There are two methods of administration, either as a percentage of cement or lime, or a conversion into clinker and calcium hydroxide.

A few years ago, their contents must be stated quite accurately, as you could meet to be shot, approx. 2-3, and up to 5% depending on the quantity. Currently, perhaps because of the complaints manufacturers can be administered fork, where the margin is quite significant. As an example, when the content of cement is circa 15% you can be given that the composition is from 10 to 20 or even 25% of cement, lime if the amount is approx. 1-1.5% - the upper limit is 3% after the crossing rises to 10%. You may, however, be assumed that the quantity of cement not exceeding 17-18%, while the more powerful the cement, the less it can be used, and the finer granularity, the closer is the upper limit. For the lime values are usually found either 2% or 5-7%.

On the German side you can meet even distinguish whether it is a white cement, or the gray, sometimes it is of two types - because you can easily buy a white low alkaline cement, and are much stronger than gray

If the description on the German and Polish data sheets read, that the product contains slaked lime or ordinary, and not in the information about the ingredients, you can be almost certain that it is produced by a chemical already in the process of mixing with water. Such a reaction is not especially difficult or dangerous, and the person doing the plaster in place at the construction site, rather than buying ready-mix use it. If you suspect that something like this could happen - just check the amount of water that is needed to sack the plaster or mortar, and amounts to approx. 3.5 l, usually revolving around 3 l with very small tolerances for error us to confirm.

c. Dust, or exposure controls and personal protectionIn this section quite often we can learn how cement was applied. In theory, it should be of type I, without additives, but, in practice, large additions of chemistry make that manufacturers use considerably cheaper cements with additives. The principle is simple: chemistry and so can handle in typical cases.

If there is only one type of cement, type I (that is, in theory, without additives) should be seen that only the dust which mixing (flowing, and more specifically to a given working premixed) is exposed, to a Portland cement dust. Such cements are specified in the standards and in theory know exactly what it is or can be. In practice, however, often can be seen that working is exposed to the dusts metallurgical cement or ash - and that means that to create the highest quality product used in practice, such a cement that really content and composition of these dust depends on how coal was burning power plant, which is the process technology, and finally on whether uses biomass. The same applies to the question of how the dust came from the steelworks

d. Another issue is the possible contents trass. In theory it should so aerate the mix, produce the amount of pores that have not had a chance to leave any discoloration, and increase resistance to moisture mixes - especially if it is used as an additive to plaster essentially limestone, which formerly strength increased, among others by adding slaked lime (lime cake), for example. calcareous tuffs, crushed burnt lime or other organic substances containing calcium (such as egg shells, bones, carcasses or even curd).

Unfortunately, the "quality" of cement, or rather the lack of it, too much scale, ignorance of what the mortar is responsible for what, trial shortcuts in the ready-mix result that in fact the vast majority, if not almost all the plaster or mortar despite trasu contents are described as not "eliminate" and "substantially limiting" the risk of discoloration. This means that the manufacturer actually washing his hands if something happens, because he wrote about the "limitation", which excludes cases in which this "our" will certainly be ranked among.

Seeing a technical consultant or talking to a sales representative, let us ask him for the card product and characteristics, even let print at talks if there is such a possibility, and let us ask the question: What is the difference between what it offers from what can be done on site, why is there such and not another substance (cement cinder), why although it is written that there is no lime, everything indicates that it is made "chemically"

It is the answers to such questions will be able to really judge how good the quality of the mortar is offered to us, and as far as actually worse than this, that a good contractor can be done here and now, but a lot - typically an order of magnitude - cheaper.

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