DE2647491A1 - Dense silicate concrete for large building elements - from quartz sand, lime and water with surfactants and/or synthetic tanning agents - Google Patents

Abstract

Prod. of a dense silicate concrete for large building elements from quartz sand, lime and water is improved in that, already in the first grinding stage, surfactants (pref. carboxylic acids, amino alcohols or other cpds. contg. OH gps.) and/or synthetic tanning agents are added. Alternatively, these additives can be introduced into the lime during its grinding or slaking; or in the mixing stage. The prods. are then autoclaved. The early stages of the concrete prepn. are facilitated and accelerated by introduction of surfactants or synthetic tanning agents.; the lime-slaking conditions are improved; the workability of the fresh concrete is improved; the strength of the prod. is increased.

Description

Process for the production of silicate concrete

The invention relates to a method for lowering silicate concrete, especially for dense silicate concrete for large-format building elements.

It is known that masses for dense silicate concrete from 6.0 # 12.5 % Quicklime with a CaO content of 2 80% 6.7 - 14.0% quartz sand ground with a SiO2 content # 90% 73.5 - 87t3% quartz sand O - 4 min 13.5 - 18.0% water produced been. Instead of quicklime, the same amount of hydrated lime can also be used will. The mixture of all components can either be done simultaneously or in a reasonable manner Order one after the other. This mass is then shaped in the usual way, compacted under vibration and then with steam in an autoclave in a certain Way hardened.

The following composition is also known: 4.0 - 8.5% hydrated lime 1.5 - 4.5% cement and / or quicklime 0.5 - 2.0% anhydrite 6.7 - 37.5% quartz sand ground 47.5 - 37.3 1 quartz sand 0 - 4 am 13.0 - 18.0% water The additional cement and / odex quicklime and the anhydrite cause a pre-improvement of the flowability of the masses and bind the previously required excess water after compaction. According to this proposed procedure, the increase in the flowability of the general Difficult to compact silicate concrete masses by adding plasticizing and / or Air-entraining additives @ can be achieved without working with excess water must become. The cement and / or quicklime content and the anhydrite remain as the fluidity-promoting additive received.

It is; Also known that high-strength silicate concrete is obtained, if quartz flour with hydrated lime in a weight ratio of about 45:55 and up to 65% aggregates made up, mixed, shaped, compacted and hardened with water will. For high-strength silicate concrete, the quartz powder is supposed to be according to the exclusion patent the GDR No. 58 465 have a fineness of 5 to 90 / um, the maximum fineness limited by the following particle size distribution, shown as residue R in percent becomes: grain size sieve residue R in um in% 5 7 °, 5 10 59.5 20 r10.2 40 15.7 63 3.5 90 0 This means that the fresh concrete is mixed and compacted with more al.s 15 wt .-% free water, the excess water enables compression without the use of presses. Even with simple vibration compaction structure-free compacts are to be obtained. That in the compression excess During this process, escaping water is passed through absorbent inserts, sieves or drainage drained.

The disadvantage of this known method is that by individual Measures at individual process steps Improvements achieved in one place that are due to additional technical and economic effort elsewhere must be bought. They lead in the process of grinding, of the burning lime quenching and condensing into disproportions in the mastery of material processes, which ultimately at the expense of the technologically required time and Continuity of the process is important.

The invention aims the production of dense silicate concrete for large-format components avoiding the disadvantages mentioned by the industrial manufacturing process safer through the complex application of a measure can be mastered and reduces the workload.

The invention is based on the object of a method for production to propose dense silicate concrete, at which already in the initial stage of the process by adding more surface-active Substances and / or tannins the grinding fineness is increased or, if the fineness remains the same, the grinding time is reduced and a delay and equalization of the quicklime extinguishing, an improved Processability of fresh concrete without excess water and increased strength can also be achieved with a reduced proportion of ground quartz sand.

According to the invention, this object is achieved in that preferably the following surface-active substances and / or tannins are used: carboxylic acids Amino alcohols compounds containing hydroxyl groups synthetic tanning agents, with any mixtures of two or more of these substances are also possible. The concentration for these surface-active substances and / or tannins is based on the dry substance of the silicate concrete mass, 0.005% by mass to 0.15% by mass, preferably 0.02 mass% to 0.10 mass%.

By using a fine grinding unit, such as a Vibrating mill, and the application of the surface-active substances described or tanning agents as a grinding aid Obtain quartz sand as a binder component. The fineness of the quartz sand must be there in the fineness range between the grain size distribution 1 and 2, as Siebrückotand R in Percent are shown: Table 1 Grain size Grain distribution Grain distribution in jum 1 2 5 69.0 42.5 10 57.0 25.5 20 37.0 9.0 40 15.5 0.7 63 5.5 0 90 o O The advantage This measure consists in the fact that the proportion of ground quartz sand in the concrete mass reduced to 3.0 - 6.0 mass% without loss of strength; can be because that too SiO2 from the extremely fine ones reacts to the strength-building CSH phases Quartz sand micht @erringert wrid. If the SiO2 conversion is usually 20 - 30% by mass of the ground quartz sand, the SiO2 conversion is when using the very fine Quartz sand in the area of grain size distribution 1 and 2 au9 70 - 80% by mass of the ground Quartz sand. The reduction in the proportion of ground quartz sand reduces the risk of cracks in hardened concrete element. Despite lowering the proportion of ground quartz sand 3.0 - 6.0% by mass is due to the liquefying effect of the surface-active Substances or tannins improve the flowability of such masses.

The object of the invention is also achieved by the following principle solved: Di @ achievement of a viscosity minimum for mi @ water made usual Silicate concrete mass is achieved when the quartz sand hits a specific surface from 3000 - 5000 cm2 / g is ground. This quartz sand surface is in fine grinding units even without the addition of surface-active substances or tanning agents as grinding aids attainable It has surprisingly shown that this quartz sand fineness regardless of the quartz sand and lime content in the silicate concrete mass, always at one Minimum of the viscosity of the fresh concrete leads.

The amount of lime in the silicate concrete mass can therefore be from 5.0 - 13.0% by mass and the amount of ground quartz sand range from 7.0-20.0 mass%. The advantage this measure consists in improving the shape of large-format components, d. H. in an equalization of the vibration compaction over the entire area of the component without additional load. There will also be an increase in strength of the concrete.

In the further expansion of the process, they become additionally surface-active Substances or tannins of the silicate concrete mass in the concentration range already specified added, then the minimum viscosity of the fresh concrete is due to its liquefying Effect shifted to even lower viscosities, so that even from an addition the effects can be spoken of.

The quick lime processing within the production technology of the Silicate concrete is also made with the addition of surface-active substances or tanning agents until the use of the Quicklime in the silicate concrete mass. The quicklime grinding with a usual grinding fineness of 10% sieve residue smaller 90 @um is achieved through the addition of surface-active Substan-2s or tannins with the same grinding fineness significantly accelerated, or with the same mill throughput the grinding fineness is increased.

When the quicklime is extinguished, generally extinguish in the first phase of extinguishing its fine components remove very quickly whereas the quenching speed through larger grains are reduced as the quenching time increases. The ones already used for grinding introduced surface-active substances or tannins delay @ the high rate of extinguishing The free components of the quicklime, on the other hand, influence the rate of extinguishing larger grains because of their smaller surface only insignificantly, so that besides an extinguishing delay achieves a smoothing of the extinguishing; will can. Dio delays in slaking the quicklime or the partially slaked quicklime when mixing the silicate concrete mass mixed with water has the essential advantage, that the processing time is extended in the shaping of the fresh concrete.

Fresh concrete production involves mixing the solid silicate concrete components with the mixing water O The surface-active substances or tannins that are used in the ground quartz sand or in the ground lime component with the grinding or during the mixing of the fresh concrete in the concentrations described are added, lead to a reduction in water requirements, thereby affecting anything Excess water can be dispensed with. In addition to the improved flow of the Sillkat fresh concrete the suppleness of the fresh concrete is increased.

Strength differences due to the formation of layers and inhomogeneities in the concrete structure are thereby switched off.

Another effective measure is given when the surface-active Substances and / or tannins in compliance with the specified concentration range pro rata to the grinding process stage and to the mixing process stage in can be added in any ratio. It is still successful if one Mixture of two or more interface active substances and / or tanning agents is produced and this is used.

The concrete strength of the concrete elements hardened in the autoclave improved by the quartz sand in a fine grinding unit with the listed surface-active Substances and / or tanning agents in concentrations of 0.005-0.10 mass% gemah len will. The grinding aid effect of these substances results in a finer quartz flour preserved than with the usual grinding. This higher fineness of quartz flour causes a improved CSH phase formation in the autoclave and thus higher concrete strength in the Silicate concrete element.

Are the surface-active additives and / or tannins only when Mixing added to the silicate concrete mass leads to the liquefying effect of the additives to the well-known reduction in the water requirement of the fresh concrete mass, whereby ei @ e better compaction becomes possible, which in turn increases the strength of the concrete is expressed.

The proposed measures, i. H. influencing all process stages the production of silicate concrete through surface-active substances and / or tannins, prove their effectiveness in technical and economic terms.

The invention is to be explained using the following exemplary embodiments : Example 1: The use should be in the form of a tabular comparison of surface-active substances and / or tannins when grinding quartz sand less than 3.15 mm in a ball mill as well as in the silicate concrete mass (compaction and hardening) with respect to the surface-active substances and / or tanning agents free materials are shown (expressed as a percentage increase).

The following surface-active substances and tannins were used: From: the group of carboxylic acids a mixture of synthetic fatty acids with a hydrocarbon chain length of C4 to C6, from the group of amino alcohols triethanolamine, from the group of hydroxyl-containing compounds the dodecyl alcoholO The tannins became the synthetic tanning agent dabrogan chosen. The additional concentration is in each case 0.05% by mass, based on the dry substance. percentage increase compared to additional-free materials Process stage fatty acid C4-C6 triethanol dodecyl dabrogan amine alcohol Grind + 15.0 + 25.0 + 20.0 + 10.0 Baseline 2000 cm2 / g Compression d. Fresh beions + 65.0 + 43.0 + 35.0 + 50.0 -Fluid- (Slump) Hardening of the Silicate concrete + 12.0 + 14.0 + 10.0 + 7.0 -Compressive strength- Baseline 300 kp / cm2 Example 2: On the basis of Example 1, the surface-active substance triethanolamine and the synthetic tannin Dabrogan are added proportionally with a concentration of 0.03% by mass each, based on the dry substance, for grinding and mixing. The quartz sand is ground with triethanolamine, the most effective grinding aid, the improvement according to Example 1 being achieved. When mixing the silicate botoh mass, the same amount of Dabrogan is added with the mixing water.

The improvement of flowability and compressive strength (hardening) the values for Dabrogan are at the same level as in Example 1.

Example 3: According to Example 1, instead of a surface-active Substance a mixture of two surface-active substances to fatty acid C4 bis C6 and 50% triethanolamine in a concentration of 0.05% by mass, based on au9 the dry substance added to the quartz sand to be ground. Improving the Grinding at an initial grind fineness of 2000 cm2 / g is in this Case 21.0, for the flowability 52.0% and for the compressive strength be; one Starting value of 300 kp / cm2 5.0%. Example 4: In one continuous working vibratory tube mill, quartz sand with a grain size of less than 3.15 mm is added of 0.05% triethanolamine to the following fineness (as shown in the sieve residue) ground: grain size grain distribution in around R in% 5 62.0 10 43.0 2 () 25.5 40 6.7 63 0.9 90 0 5.0% by mass of this extremely fine quartz sand instead of 12.0% by mass of the commonly used quartz sand from 1500 to 2000 cm2 / g into the silicate concrete mass introduced. The flowability of the fresh concrete is despite the reduced quartz sand content due to the surface-active substance in the same order of magnitude as fresh concrete with quartz sand with a fineness of 1500 to 2000 cm2 / g. The crack-free hardened concrete elements have the same compressive strength of 300 kp / cm2 as the elements with the low Quartz sand fineness.

Example 5: Quartz sand with a grain size of less than 3.15 mm is placed in a ball mill au9 a fineness of 3700 cm2 / g ground, the silicate concrete mixture is composed Made of: 5.6% by mass CaO 9.7 "quartz sand of the above fineness 84.7" quartz sand O - 3.15 mm 9.2 "water This silicate concrete mixture has a fineness of quartz sand compared to mixtures with of 1700 cm2 / g or 6300 cm2 / g an embossed viscosity minimum, so that a complete encasing of the steel reinforcement achieved when compacting under vibration will. Compared to the silicate concrete mixture with a quartz sand of 1700 cm2 / g In addition, an increase in compressive strength from 300 kp / cm2 to 410 kp / cm2 possible.

The silicate concrete mixture described becomes 0.05 with the mixing water % Fatty acid 04 - C6, based on the solids of the mixture, was added. The viscosity minimum of the fresh concrete or its flowability is increased by the same amount according to the example 1 additionally reduced.

Example 6: Quicklime is 0.10% fatty acid C4 - C6, based on the solid, added and ground in a ball mill to 6000 cm2 / g. Bel the The same sample without surface-active additives was only used for the same milling time obtained a surface area of 5100 cm2 / g.

The rate of slaking of quicklime according to the Pleva method is reduced by the use of 0.10% fatty acids C4 - C6 compared to the additive-free quicklime sample in the following way: Extinguishing speed in ° C / min Quicklime after a quenching time of: 5 min 10 min 30 min 60 min without addition 4.19 1.26 0.23 0.00 0.10% fatty acid 0.70 1.11 0.48 0.08

Claims (7)

Claims process for the production of silicate concrete, in particular for dense silicate concrete for large-format building elements, essentially consisting of quartz sand, lime and water, characterized in that already in the first Process stage of payment of surface-active substances and / or tannins, preferably Carboxylic acids, amino alcohols, hydroxyl group-containing bonds and synthetic ones Tanning agents are added to the silicate concrete components quartz sand and / or lime, those in the further process stages of quicklime quenching, mixing and the shaping until the concrete elements have hardened in the autoclave. 2. The method according to claim 1, characterized in that the concentration of the surface-active substances and / or tannins in the silicate concrete mixture 0.005% by mass to 0.15% by mass, preferably 0.02% by mass to 0.10% by mass, based on the dry substance of the silicate concrete mass. 3. The method according to claim 1 to 2, characterized in that the surface-active substances and / or tannins proportionate to the process stage added to the grinding and to the process stage of mixing in any ratio will. 4. The method according to claim 1 to 3, characterized in that a surfactant or tanning agent, or a mixture of two or more surfactant Substan zen and / or tanning agents is used. 5. Ancestors according to claim 1 to 4, characterized in that in a fine grinding unit and with the addition of surface-active substances and / or Tanning agents a very fine quartz edge for the silicate concrete mass with a fineness ground between the particle size distributions 1 and 2 according to Table 1 and with a proportion from 3.0 to 6.0 mass% is introduced into the silicate concrete mass. 6. The method according to claim 1 to 5, characterized in that the Quicklime when grinding and / or quenching surface-active substances and / or Tannins are added. 7. Process for the manufacture of silicate concrete, especially for dense Silicate concrete for large-format building elements, mainly consisting of quartz sand, Lime and water, characterized in that for setting the minimum viscosity In the fresh concrete, the ground quartz sand contained in the silicate concrete mix has a Specific surface area of 3000 to 5000 cm2 / g, preferably 3500 to 4000 cm2 / g, in proportions of 7.0 to 20.0 mass% and a lime proportion of 5.0 to 13.0 mass%, based on the dry substance of the Silikatbeto @ mass.