DD222292A1 - METHOD FOR INCREASING THE PRESSURE STRENGTH OF BUILDING BLOCKS - Google Patents

Abstract

The invention relates to the building blocks produced using lignite filter or fly ash with a high proportion of free lime, in particular by the lime-sandstone method. These building blocks can be qualitatively improved by aftertreatment in a second process stage by increasing the pressure resistance. The quality improvement is achieved, in which the free lime still present in the building block is transferred to the slaked lime and then used to reinforce the bond in the building block.

Description

Title of the Invention: ': -

Method for increasing the pressure resistance of building blocks

Field of use:

Production of building blocks consisting mainly of lignite filter fly ash or fly ash

Characteristic of known solutions:

It is known that building blocks with sufficiently high compressive strength can be produced using coal fly ash, Bunakalk and water.

Building blocks with high pressure resistance can, while maintaining certain mixing ratios of lignite filter ash. Cement. Metallurgical pumice, and water are produced (TIZ Technical Reports No. 6/82).

- Moldings from the flue dust of power plant and / or Heizwerksfeuerungen can be produced. by airborne dust with an aqueous binder of a mineral oil in Wassei emulsion "formed into green compacts and the green compacts are molded into moldings (DE OS 30 _, 20 006 C2, IPK C 04 B 31/10).

- Building blocks, which are prepared by the lime-sandstone process using a high proportion of lignite filter or fly ash, in particular then have an insufficient compressive strength. if a high proportion of harmful components is present in the ash, in particular free lime (CaO), - (TKO report).

- Calcareous fly ash is hardened using water and granulated (DD WP PS 86 333. IPK C 04 B 31/10).

Object of the invention:

The aim of the invention is. the compressive strength of such blocks, preferably made by the lime-sandstone method, whose filter or fly ash components have a higher proportion (greater than 2%) of free lime (CaO) without increasing any particular additives.

Essence of the invention:

According to the invention, the compressive strength is increased by moistening these blocks, which have been produced by the lime-sandstone process using Bunakaik and lignite filter fly ash or fly ash with a higher proportion of free lime, after the first hardening and subsequently curing them by repeated heat treatment and drying them ·.

The following process steps are required:

The lignite filter or fly ash is first mixed dry with Bunakalk in a screw or drum mixer. By adding water to the mixer, a soil-moist mixture is prepared. Without intermediate storage, building block pipes are then pressed out of this earth-moist mixture.

In the resulting module blank Bunakalk and free lime is now included among other components. The free lime is already in the addition of water in the process of wet mixing and then further in the blank partially in slaked lime (Ca (OM) ,,) reacted. The subsequent after fabrication de _v s blank heat treatment in an autoclave for curing the blocks interrupts this investigation process quicklime. in slaked lime, because the still existing water in the building block is used up with the binding of the Bunakalkes and the already formed slaked lime with the ashes. The due to the interrupted implementation process of quicklime (free lime) in slaked lime after hardening in the block still contained free lime causes the structure in the block is not yet 'sufficiently solid. · .. ·:

Subsequent moisture penetration after curing has the consequence that the process of the reaction of free lime, which has already begun in the as yet uncured component blank. the. was interrupted by the hardening, continued and can be completed ... After a sufficient reaction time, the remaining free lime, still converted into slaked lime, is used by means of a repeated heat treatment to reinforce the bond already existing in the building block.

, Ausführungsbeispiei:

In a drum mixer, test amounts (50 dm ³ each) of - 17 vol.% Bunakalk and 83 vol.% RBK filter ash; rough

(free lime approx. 3%) from the HKVU Jena as well as -17 vol.% Bunakalk, and 83 vol.% RBK _T Fiiterasche (free lime approx. 32%) ^{from the H} ! 5 ^{W Gera}

first dry and then mixed with earth-moist water by adding water.

From these two mixtures wall brick blanks in the format 240 χ 115 χ 71 mm were pressed in each case in a rotary table press. These are then cured in an autoclave for 8 hours with steam (130 C, 3 ata). -

After this process step, a sample was taken for a compressive strength test, which was carried out in the autoclave 4 hours after the treatment.

The remaining building blocks were immersed in a water bath for 10 minutes and completely moistened. After a period of 4 hours, the second heat treatment in the autoclave began. After, the conclusion took place after 4 hours, a second pressure resistance test.

The comparison of the results of the pressure strength tests of the first and the second process stage showed an average increase in the compressive strength to 183%. , , ,

Claims (3)

Invention ξ to saying: A method for increasing the compressive strength of building blocks, which are prepared using lignite or fly ash with a high proportion of free lime, preferably by the lime-sandstone method, characterized in that after the first curing of the blocks -a second Process stage follows. The second stage of the process. includes a moistening of the blocks, a reaction time for the implementation of still existing in the block free lime in "slaked lime and a Nachhär.tung by a 'heat treatment after moistening .. 2. The method according to claim 1, characterized in that the time required for the second process stage amount of water for moistening the blocks, the reaction time and the duration of the heat treatment after soaking determined from the amount of free lime, which is located in the used ashes. ^ 3. The method according to claim 1 characterized. that the. Moistening of the blocks by, immersion in a water bath or by wet steam treatment in the autoclave happens.