DE1571330B1 - Process for the production of steam-hardened, possibly porous granules - Google Patents

Description

The invention relates to a method for producing steam-hardened, Lime silicate hydrate or lime silica aluminum hydrate bound, possibly more porous Granules and is characterized by being a hardenable mixture in an autoclave granulated and fully cured under steam pressure at the same time.

Cure hardenable mixtures with steam to so-called steam-hardened Manufacturing building materials is well known.

These hardenable mixtures mostly consist of hydrated lime and sand and water. -The hydrated lime used in such mixtures can be partly or also be replaced entirely by bases, such as caustic soda or soda, and portland cement, and The sand can also contain considerable amounts of clayey substances.

Under the hydrothermal conditions of hardening arise predominantly Lime-silicate hydrates and lime-silicate-aluminate hydrates, which give the product the desired Grant strength.

Saturated steam is mostly used to harden these mixtures, however, at very low pressures, the use of superheated steam is appropriate.

In general, these mixtures become shaped articles before curing pressed or the mixtures made pourable with water poured into molds, which bind in the forms and can then be removed from these.

Due to the water content of the pressed or tied moldings the degree of porosity of the cured moldings can be regulated as is known. The additional use of foaming agents and / or pore formers can reduce the porosity can be increased significantly.

The pourable masses must, if one is in a curing process moldings wants to be hardened in the molds. However, this turned out to be a nuisance, therefore the hardening was divided into two stages. In the first, the so-called pre-hardening, the mixture was partially cured. This semi-hard mass was crushed and with or pressed into moldings without aggregate and "hardened" in a second hardening process.

This known procedure was followed by a further known method modified in such a way that the pre-hardening was carried out in a rotating vessel, at the end of which the vapor pressure was suddenly lowered. Through this relaxation however, the mass crumbled by the rotation of the vessel during the pre-hardening process torn and a pile of crumbly, spattered, but not very porous particles obtained, which were then deformed and cured with or without aggregates.

In this prior art, the task arose of a method to find through which hardened, possibly porous granules, which as Building materials or aggregates are suitable manufactured in a single operation can be.

During the development work it has now been found that a curable Mixture in a rotating autoclave is granulated at the same time and under steam pressure can be fully cured.

The hardenable mixtures preferably consist of floury-fine solids with a particle size below 0.1 mm. However, coarser mixtures can also be used in the same Way to roughly spherical shapes. Granules produced in this way can be used as lighter aggregates in concrete construction.

Depending on the water content of the raw mixtures, which also include pore formers can be added, if sufficient strength is observed, more or less porous granules obtained, which then according to their porosity for lightweight concrete or can be used as an isolating agent.

The average size of the individual granules is determined by regulates the peripheral speed of the hardening drum; the greater the speed, the smaller the granules.

According to the invention, granules with different porosities can also be used produce.

So you get z. B. Granules with a core of great porosity, which is enclosed by a denser and firmer shell, by being first produces hardened granules with great porosity, whereupon this in the same Autoclave a water poor mixture is added, which the highly porous granules shell-shaped.

By repeated steam treatment in the rotating autoclave this Encapsulation hardened into denser and stronger shells of the individual particles. That the product obtained in this way is, in spite of its high porosity, more mechanical than that Very resistant to stress.

Claims (2)

Claims: 1. Process for the production of steam-hardened, lime silicate hydrate or calcium silicate aluminate hydrate bound, possibly porous granules from hydrothermal hardenable granules, d a -characterized in that a hardenable mixture in one Autoclave granulated and fully cured under steam pressure at the same time will. 2. The method according to claim 1, characterized in that first Granules of high porosity are produced, which have a lower water content hardenable Mixture is added for the purpose of enveloping the highly porous individual particles, whereupon the steam treatment in the rotating autoclave to harden the denser and stronger ones enveloping layers is repeated.