Mythical mortar with trass

A few years ago on the market related to the broader conservation and restoration of monuments existed a new miracle cure for emerging from many years of problems with gray-white raids and eruptions. There is a mortar based on trass from the Rhine valley. On the basis of - because in some cases the amount is almost half of the composition, and the route - as in other amount is sometimes a trace and is usually less than 5% of the total mixture.

Trass serves two functions - due to the mineral composition is a measure that makes the mortar is hydraulic binding in the presence of moisture. The most important components that contribute to this property silicates, or silicon oxide SiO2, and aluminum oxide (aluminum). This means that fully exactly the same role as the cement, and some products called lime-route judging by the composition are actually double hydraulic mortars, which are binding materials: trass and cement.

The second - for us more important - role is that because of its physical design of routes is an ingredient that naturally physically aerated mix, allowing you to accumulate inside these raids and efflorescence (or really alkali), and not allowing them to come to the outside.

Rhine trass, as its name suggests, is a volcanic rock coming from the area of the Rhine valley, similar composition and that serves the same function as the Italian natural stone from around the Italian town Pozzouli.

In the old days really the most important, and only were considered hydraulic properties. Other one too was not interested. This was a very simple and prosaic reason. At that time, the mortar used in construction until the mid-nineteenth century, and in many places, and more, they were almost exclusively strictly limestone. These in turn as the air slowly bound and did not tolerate water. Of course, the mortar of lime created based on slaked lime - lime cake. Due to their composition did not exist the problem of air raids or other efflorescence, and aeration of mortars was natural - it provided a lime putty.

In the old days really the most important, and only were considered hydraulic properties. Other one too was not interested. This was a very simple and prosaic reason. At that time, the mortar used in construction until the mid-nineteenth century, and in many places, and more, they were almost exclusively strictly limestone. These in turn as the air slowly bound and did not tolerate water. Of course, the mortar of lime created based on slaked lime - lime cake. Due to their composition did not exist the problem of air raids or other efflorescence, and aeration of mortars was natural - it provided a lime putty.

The polish library resources available is quite a lot of studies dating back to the seventeenth century, and on how to build and how to make mortar.Some of them are just simple advice, some of it important books counting of several hundred pages giving different ways of getting the mortar was hydraulic. The vast majority of them simply involves the use of various forms of lime - of crushed normal burnt by the slaked mixed each other in various proportions with oil, various kinds of clay. What is interesting as an ancient method is not mentioned trass, but just the italian puzzola. In the 50s of the twentieth century in one of the periodicals came to develop, in which the author thoroughly examined the mortar of the old ages, specifying their amount of sand and carbonates (calcium compounds), and something called a hydraulic factor, or additives to aid bonding mortar humid environments. The composition of mortars is very different - both in terms of the contents of calcium (more specifically the compounds), and the amount of sand remaining on these additives. Second, this time the original nineteenth-century (40 years, Cracow) publishing house, is something that can be called the catalogue physical inputs, which accurately defined the composition of the mortar (two parts sharp sand, one part lime cake, of course, volume) amount per square meter of plaster any number of centimeters, wall thick on any number of bricks etc. Including the costs of transport of stone, the source of its acquisition etc. of course, sources are the closest to the city - near Krzeszowice, Rudawa (today here are still operating quarries), Podgórze (now a district of the Cracow).

This allows us to conclude that the origin of the materials used en masse on construction sites for basic work, not only the nineteenth century but earlier they were as far as possible collected in the immediate area, hence the multiplicity of ways to made hydraulic mortars, dependent areas of which came from or where he worked professionally author of the paper, book etc.

Half of the nineteenth century brought a revolution - entered the arena of cement, initially romanesque (drawback: heterogeneous composition), something intermediate between burnt lime and portland cement (more hydraulic and higher strength of lime mortars). Was published the first studies describing its characteristics, advantages and disadvantages, composition the mortars. Only after that period for the first time began to appear both trass and puzzola, but only as hydraulic additives, and not providing the mortar without efflorescence. In the first decade of the twentieth century in the United States for the european market reached the first standards and develop as to what parameters have to achieve cement. Very quickly gained acceptance throughout the world. At the same time, successive authors of manuals for construction, especially since the 90s nineteenth century began to serve alongside the mortar cement-lime and lime-cement, initially only somewhat beside the then traditional - the pure limestone, then essentially taking as the main and most important of these based on cement.

In the 30s of the twentieth century came the development of talking about how cheap and easy to build a brick house is not ceramic, not clay, but cement. Obviously the author (or rather the authors) did not forget how easily and quickly make him suitable quality plaster and mortar. In any of these books and studies did not show up trass.It has its place - but it is in lectures at universities, in addition to the old hydraulic mortars, one of many anyway. Next to him - other local. Nowhere, even in higher education, not to mention the efflorescences on concretes, plasters and so on. This does not mean that the problem does not exist, but perhaps it is so marginal that hardly anyone on it at all points. Of course, it is clear and obvious that the composition of cement lime is not in the form of hydrated lime, but lime cake. Changes only one thing - time of its extinction. Initially, these were the years (up to ten) it reduced it to two seasons, finally back in the 50s - for weeks. In popular in Poland handbook for rural builders from the 40s and 50s (several editions, almost every year) are the types of cements, of the class 150, any number of blend compositions, but never mentioned what can mean efflorescence. This means that the problem was at the time (mid-twentieth century!) was so insignificant that nobody paid attention to him.

One of the last chords "good old days" are the recommendations of the american society of dealing with cement. At the beginning of the 40s it was found that the amount of alkali in the cement than 0.6% disqualify it in terms of quality. Today, these results apply only low alkali (LA) cements and rarely are the cement type CEM I. Significant and important books which are in the 70s in a "bible" of dealing with the broad construction, namely Guide the Construction Foreman (well over a thousand pages, a few editions of 60s) and Engineer's and Technical Building Guide (several editions in different variations on the amount of volumes) continues as an important part of mortars and plasters exchange not only hydrated lime, but extinguished.As the authors note both of these books, hydrated lime suitable after extinction to use much faster than the "typical" roasted, which must be put out at the time calculated in weeks. With one exception, still mortar compositions are given in volume and composition and is close (provided, of course, mortars or renders) in the range 2: 1 to 1: 2 (in terms of volume fraction of cement and lime). About efflorescences also nothing is written.

Talking to people who still remember those times, you can find one - that basically still in private construction foremen usually not used the hydrated lime, but the lime putty, which was obtained by flooding purchased lime in an old barrel or tub and wait for a few days.

What does this really mean? Some very important things:

1. Trass initially was treated not as a means of protecting the efflorescence, because this problem is not known for very long centurys, and it was connected, among others, the purity of cement, but as a means to get hydraulic of the mortars or plasters. This means that at the moment it is replaced with a very good effect for ordinary cement

2. Aeration, ie, the ability to create places where you may collect it, which should not go out (nota bene addition of blowing agents is now a normal way of getting frost resistance of cement mortars with a high percentage of cement), assured the addition of lime cake, giving plasticity to the corresponding mortar. Many years ago, experts called this last feature "being like a butter"

3. Assuming that adequate aeration means a specific degree of diffusion, allowing its use in the renovation works and knowing how to provide hydraulic, you can easily conclude that it is enough to dust off the old recipe from the '60s or the early 70s to get a mortar or plaster with the desired strength, diffusivity, and suitable for applications where the currently used mass ready-mixed with trass.

Proper understanding, what it was the initial and crucial role of the trass in the mortars, why it was not known and used in a large part of Europe, or more precisely in the areas of contemporary areas f.ex. of the east part of Germany, Russia middle Europe, knowing what properties have lime putty and what were its limitations, and how they were overcome, and in the end why, despite this cake limestone was an important and equally important component of the mortar as the cement itself, will allow us to understand that there really anyone alone on the site can afford to make the mortar corresponding to the best mortars en-route reputable companies available on the market. Of course, a lot less.

If you build up all this knowledge of how changing certain parameters of cement and what kinds of them were the basis for the mortar used commonly in the 60s (ie. 250, with a rare and exceptionally for stucco 350; now correspond respectively cements type: 22,5 and 32,5), it turns out that the knowledge of a few basic recipes plaster, which was once common, we are able to do not only trass mortar corresponding en-route or another very well-known company, but this mortar suitable and adequate to the needs posed by the object currently being renovated and restored.

Talking privately with the so-called contractors environmental conservation should ask simple basic and almost a "killing": how in the 80s or even 70s was renewed monument: plaster, grout, mortar formed as necessary to re bricklaying this or that piece of the destroyed? The answer will be many shocking: quenched lime, cement and sand were added, which is simply mixed them on the site, by modifying the composition of the current demand and the conditions that have created renewed object.

About the trass and its miraculous properties, few have heard, on the other hand, salting out or efflorescence not been a problem, which was the most important and around which shook the world.