Back in the 1950s, the Estonian scientist, inventor and business executive Johannes Rudolf Hint developed a new building material - silicalcite. Derived from sand and limestone, common materials, this material has proven to be much stronger than concrete. It was possible to make a variety of products from it: blocks, slabs, pipes, tiles. In Estonia, the Hinta organization built silicalcite houses that did not require the consumption of cement and reinforcement.
Hint had a complicated biography. He graduated from the Tallinn Polytechnic Institute in 1941 with a degree in civil engineering, but supported the newly established Soviet power in Estonia and even joined the Communist Party (his brother Aadu was a communist), then led the evacuation of Estonian industry after the outbreak of war, was left underground work. In 1943, he was arrested by the Germans, but Hint managed to escape from the death sentence by boat to Finland, where he was arrested again and placed in a prisoner of war camp, where he remained until the end of the war with Finland. After the war, he created silicalcite, developed the technology for its production and processing, created a large enterprise, and even in 1962 received the Lenin Prize for this development.
The end of this story was unusual and somewhat unexpected. In November 1981, Hint was arrested on charges of abuse of office and sentenced to 15 years in prison. All his titles and awards were canceled, and his property was confiscated. Hint died in September 1985 in prison and was rehabilitated in 1989. But his main brainchild, silicalcite, was never rehabilitated and did not enter widespread use, despite the beneficial technological and economic aspects. Only in the last ten years, interest in silicalcite is reviving, it is being promoted by enthusiasts.
The Hint case was strongly politicized, I think, because, according to common sense, silicalcite was supposed to oust cement from construction with all the ensuing consequences of the reorganization of the whole construction materials industry: the closure of cement plants, the conversion and re-equipment of the construction industry, changes in standards, and so on. The reshuffle caused by the introduction of silicalcite into widespread use promised to be so large-scale that some found it easier to jail the initiator of these innovations, at the same time tarnishing the technology itself.
However, we will not delve into the details of this long-past history. Silicalcite is in any case interesting and has, in my opinion, very good prospects as a building and structural material for military-economic needs. It is from this point that we will consider it.
Silicalcite Benefits
Silicalcite is a development of silicate bricks, also made from sand and lime, known since the end of the 19th century. Only silicate brick is very fragile and its compressive strength does not exceed 150 kg / cm2. Anyone who has dealt with it knows that sand-lime brick breaks quite easily. Since the late 1940s, Hint has been looking for ways to increase its strength and found such a way. If you do not go into technical subtleties, then the essence of the matter was the joint grinding of sand and lime in a disintegrator (a special type of mill, consisting of two circles rotating in opposite directions, on which steel fingers are installed in three ring rows; the grinded material collides with the fingers and is crushed from these collisions into small particles, the size of which can be controlled).
The grains of sand by themselves are rather poorly connected to lime particles, since they are covered with a layer of carbonates and oxides, but grinding knocks this crust off the grains of sand, and also breaks the grains of sand into smaller pieces. Fresh chips on grains of sand are quickly covered with lime particles. After grinding, water is added to the mixture, the product is formed and steamed in an autoclave.
This material turned out to be much stronger than concrete. Hint obtained a material with a compressive strength of up to 2000 kg / cm2, while the best concrete had a strength of up to 800 kg / cm2. Tensile strength increased dramatically. If for B25 concrete it is 35 kg / cm2, then for silicalcite railway sleepers the tensile strength reached 120-150 kg / cm2. These indicators were already achieved in the late 1950s, and Hint himself believed that this was far from the limit, and that compressive strength could be achieved, like that of structural steel (3800-4000 kg / cm2).
As you can see, the material is very good. The high strength of the parts makes it possible to construct low-rise buildings completely without the use of reinforcement. In Estonia, quite a few buildings were built from it, both residential (with a total area of 1.5 million square meters) and administrative (the former building of the Central Committee of the KPI, now the building of the Estonian Foreign Ministry). In addition, silicalcite parts are reinforced in the same way as concrete ones.
From an economic point of view, silicalcite is much better than cement. Firstly, the fact that it does not use clay (added in the manufacture of cement clinker). Sand and limestone (or other rocks from which lime can be obtained - chalk or marble) are found almost everywhere. Secondly, the fact that there is no need for grandiose rotary kilns for burning clinker; the disintegrator and autoclave are much more compact and require less metal. Hint once even set up a floating factory on a decommissioned vessel. The disintegrator was installed on the deck and the autoclave in the hold. A cement plant cannot be shrunk to the same level of compactness. Thirdly, fuel and energy consumption is also significantly lower than for cement production.
All these circumstances are of great importance for the belligerent economy. The military situation just makes a great demand for cheap and durable building and structural material.
Silicalcite in the war
How can you describe the military-economic use of silicalcite? In this way.
First. War, contrary to popular belief, is associated with large construction work. This is not only and not so much about the construction of fortifications and protected emplacements, although this also matters. A fire point reinforced with durable material is much better than a wood-earthen one or without any reinforcement at all. The technology for the construction of prefabricated reinforced concrete firing points (RCF), developed at the beginning of the Great Patriotic War, is well applicable to silicalcite. Silicalcite can be used to make blocks that make up the pillbox in the same way. But there is a difference. The raw materials for silicalcite can be procured close to the construction site and processed into finished products on a mobile unit (the disintegrator is very compact and easy to install on a truck, and a mobile autoclave can also be developed; not to mention the installation of a railway version). This significantly speeds up construction and makes it less dependent on long-distance delivery of materials.
A lot of things are needed to build in war conditions: housing, new and restored, workshops for various kinds of industries, roads, bridges, various objects. Many consider the experience of the Second World War to be outdated, but if another major war breaks out, they will have to turn to it, since the builders on both sides of the war worked at that time with maximum effort. And all military construction programs suffered from an acute shortage of cement, from a problem solved just by silicalcite.
Second. The high strength of products made of silicalcite, molded by pressing from a very finely ground mixture of sand and limestone and processed in an autoclave, makes it possible to use this material for the production of certain parts of equipment and ammunition. You won't surprise anyone with a reinforced concrete tank now; this method of handicraft booking is very widespread. The feasibility of this approach was proven in the T-34ZhB project, an experienced tank with reinforced concrete protection, a kind of mobile bunker.
Silicalcite allows such protection to be made stronger and lighter than that of reinforced concrete, while retaining all the advantages of steel or fiber reinforcement. In the production of silicalcite products with the strength of structural steel, it becomes even possible to replace some of the steel parts of the machines with them. For example, frames for trucks.
Further, there are varieties of foam silicalcite that are lighter than water and have buoyancy. Therefore, silicalcite of various grades, light and floating, as well as strong and solid, can serve as a structural material for the construction of ferries, ships, pontoons, including self-propelled, collapsible floating bridges, etc. If you remember the extravagant idea of building grandiose "floating islands" with which you can swim across the ocean and land on the territory of our main potential enemy, then silicalcite opens up greater prospects and opportunities than reinforced concrete.
Finally, silicalcite, following the German example, can be used to make hulls for rockets. Reinforced concrete rockets were manufactured in Germany at the end of the war and performed just as well as steel rockets. Silicalcite pipe can be stronger than reinforced concrete, and therefore lighter.
The meaning of these measures is to replace steel, which in the course of a major war will become an acutely scarce material, with a cheaper and much more affordable material in terms of raw materials and energy costs. In my opinion, it is high time to seriously think about replacing as much steel as possible with various silicate materials (not only silicalcite, but also ceramics, as well as various composites) suitable for their properties in the production of military equipment, weapons and ammunition. If it is already becoming difficult for us with iron ore resources (the Krivoy Rog deposit is now a potential enemy, other deposits are severely depleted, so now metallurgical companies are organizing the processing of ilmenite sands), then there are no problems with raw materials for the production of silicate materials, they are almost unlimited.
I got a very brief and cursory overview of the military-economic capabilities of silicalcite, without detailed justification and analysis of specific examples. I think that if you study the issue deeply enough, you will get a whole book (very plump in volume). I have a foretaste, based on my experience in war economics, that silicalcite could revolutionize the military-industrial environment and give war economies a powerful source of materials.
