FI64934C - Process for making a lime sand tile with enhanced visual effect. - Google Patents

Description

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W (11) UTLAGGNI NGSSKRIFT 64934 • (4S) (51) K * jiuVci.3 C 04 B 31/28, 31/14 FINLAND — FINLAND pi) 790371 * (22) Hikemtepihft — Anceknlnpdsg 05.02.79 (23) Alkupllvi— GiMghatadag 05.02.79 (41) Interpreters (vlklMkai - WlvK offantilg qQ Qq ^ tantti, and the register hai I Itu * («) N * tiviWp ™ is |. KuLMka ™, ™, - ' «Blic * nd ox.xu.o oo (32) (33) (31) Pyr **« * y «μοΛοιι * —8« flrd priori * · * (71) Oy Partek Ab, 2l600 Pargas, Finland-Finland (FI ) (72) Lauri Yrjö Olavi Lundelin, Kaarina, Markku Ilmari Leiritie, Parainen, Finland-Finland (FI) (7b) Berggren Oy Ab (5 ^) Method for the production of lime sand bricks with a pronounced visual effect - Förfarande för framställning med ett kalksandtegel all effects

The invention relates to a method for producing a visually impressive lime sand brick from a white limestone crushed stone which does not participate in the brick bonding process.

The color of a conventional lime sand brick as a flat and block surface is light gray. Based on market requirements, lime sand tiles of considerably whiter than normal light gray have been developed in different countries. Instead of normal natural sand, light crushed quartz has been used as the aggregate for SiO 2 / brick. Such products on the market include, for example, ^ ilexi brick, which has long been marketed in Sweden, and ^ kahi brick manufactured in Finland.

Ordinary lime sand brick can also be made somewhat lighter by adding white, finely divided titanium dioxide, TiCl 2 pigment, to the brick mass during manufacture. The pigment is generally added to the brick mass by 1-4%. Due to the high price of pigment, a brick is usually no longer competitive if the pigment content exceeds 3%. The technical properties of the 2 64934 bricks thus obtained also deteriorate, mainly the very good frost resistance required of facade bricks if the pigment is added to the brick mass by more than 3%.

It is also known from the German application DE-OS 1 916 893 to use various additives, such as feldspar, crushed glass and the like, as mineral additives in the production of lime sand bricks in order to obtain the desired color for the bricks.

The object of the present invention is to produce visually enhanced whitewash lime brick. The features of the invention appear from the following claim.

The method and raw materials used to make the brick, which is emphasized in whiteness, differ considerably from the corresponding production methods and raw materials for the sand-lime bricks currently on the market. Surprisingly, it has been found that ultra-white lime-sand bricks can be made by deviating greatly from the conventional method of making lime sand bricks by using inert, brick-free crushed limestone and natural quartz sand, which is not involved in the formation of the brick binder body. This is made possible by the fact that the binder is formed in an optimized reaction between the specially optimized components, fine quartz-containing natural sand and lime, CalOHjj, whereby the binder body of the brick is formed by a mass-distributed calcium hydrosilicate. However, the bulk of the pulp volume consists of a white filler that gives the brick a visually accentuated white impression both flat and trimmed.

The use of a limestone filler in curable base compositions is known. For example, it is already known to mix limestone in the basic state of concrete pipes. Natural lime stone filling has also been used in lime sand bricks in the past to create an aesthetic effect. In general, however, the fillers known to date are those which react with the base mass used in h 3 64934. This has been necessary to achieve the strength values required by the finished product.

It is also made of sand-lime brick with a aggregate grain size of 5-8 mm. However, the aggregate also contains SiO 2, which is why it is not inert, because the SiO 2 -containing aggregates are inert only when their grain size is 10 mm and more.

Laboratory tests have shown that strength standards can be achieved and even exceeded, even if the filler and filler used are inert according to the invention. However, this is only possible by considering the specified conditions and component ratios.

The white filler and aggregate of the brick according to the invention is crystalline. Since the selected material does not react with the binder used, its surfaces remain unchanged, which increases the light reflectance of the brick surfaces. This provides a significant emphasis on the visual effect, i.e. whiteness.

In order to clearly show the differences between the new production method and the conventional lime sand brick production, the following known method and the substances used therein are compared with the process according to the invention and the substances used therein, especially in the production of white lime sand brick. Conventional lime sand bricks are made from quicklime, quartz sand and water. Em. the substances are mixed together into a moist soil mass, whereby the lime is quenched into calcium hydroxide, Ca (OH), ». The pulp is pressed at high pressure, 20-30 MN / m, into brick granules, which are autoclaved under a vapor pressure of 1.2-1.8 MPa, whereby lime, (Ca (OH) 2, quartz sand, SiO2 and water, H 2 O react with each other to form a lime sand brick binder, calcium hydrosilicate, CHS.

4,64934

In a conventional lime sand brick, the pulp dry matter is 8-12% lime, CaCOH 2 / and 92-88% quartz sand. The SiO 2 content of the quartz sand must be at least 70-75% and likewise the grain distribution of the sand used must be such as to form a dense and cohesive brick grain during compression. The porosity of the finished sand-lime brick must also be such that the brick is frost-resistant. Porosity is affected by the grain distribution of the sand used, which should generally meet the following requirements:

Grain size Permeability mm% <0.125 10-30 <0.250 30-40 <0.5 55-65 <1.0 70-100 <2.0 90-100 <4.0 100

Known white lime sand bricks are made according to the above principle using white crushed quartz sand, which generally has a SiO 2 content of at least 90%.

Thus, in the production process of the white lime sand brick according to the invention, the main raw materials are lime, fine natural quartz sand and a coarser white aggregate crushed from crystalline limestone.

The fineness of the natural sand used in the lime sand brick according to the invention should be, for example, as follows:

Screen size Permeability mm% 0.063 20-60 0.125 60-70 0.250 70-90 0.50 90-100 li 5 64934 However, in this white sand-lime brick, the bulk of the aggregate consists of white crystalline limestone which does not react with lime in the autoclave treatment. Such aggregate is often the most readily available and is also less expensive than white crushed quartz sand. White inert limestone crushed stone is added to the brick mass 70-40% according to the desired final color shade. White aggregate is substantially coarser than the natural quartz sand used in the binder. The binder accounts for 30-60% of the lime sand mass. The binder consists of slaked fine lime, Ca (OH) -, with a specific surface area 2 ^ greater than 1000 m / kg and a content of 14-28% of the binder. The free SiO 2 content of natural quartz sand is greater than 75% but does not exceed 85%. The specific surface of quartz sand is 100-400 m / kg. The binder contains 86-72% sand.

The grain distribution of white limestone crushed stone should be, for example, as follows:

Grain size Permeability mm% 0.125 5-15 0.250 20-40 0.50 30-50 1.00 40-70 2.00 60-100 4.0 80-100 6.0 90-100

The following describes by way of a couple of examples the composition, manufacture and properties of the white lime sand brick according to the invention and, for comparison, the properties of ordinary lime sand brick and known white lime sand brick.

Example 1

The raw materials were mixed together into a homogeneous mass in the following proportions:

Composition:

Lime 14%

Natural sand 43%

Crushed limestone 43% 6,64934

Water was added to the mixture at 5% dry weight and the brick granules were pressed at a pressure of 25 MPa. The raw slags were autoclaved for 5 hours at a steam pressure of 16 bar.

The lime used was the so-called industrial fine lime with an active lime content of Ca (OH) 2 of 82.9%. The grain distribution of natural sand was as follows: 44.8% passed through a 0.063 mm sieve, 80% through a 0.125 mm sieve and 95% through a 0.250 mm sieve. The quartz content of the sand was 85%. The grain distribution of the limestone crushed stone was as follows: 15% passed through a 0.125 mm sieve, 24% passed through a 0.250 mm sieve, 35% passed through a 0.5 mm sieve, 55% passed through a 1.0 mm sieve and 78% passed through a 2.0 mm and 100% 4.0 mm sieve.

The technical characteristics of the white sand - lime brick thus obtained were determined:

Density 2020 kg / m

Water absorption 11.1% 2

Compressive strength 63.7 MN / m

Whiteness 69.5% of the whiteness of the MgO control

Frost resistance Meets the requirements of SFS standard 2803, ie withstands 25 thawing and freezing operations without breaking

Example 2

The raw materials were mixed together into a homogeneous mass in the following ratio.

Composition:

Lime 14%

Natural sand 43%

Crushed limestone 43%

The bricks were prepared in the same manner as in Example 1.

The lime used was the so-called industrial fine lime with an active lime content of Ca (OH) 2 of 82.9%. The grain distribution of natural sand was as follows: 44.8% passed through a 0.063 mm sieve, 80% through a 0.125 mm sieve and 95% through a 0.250 mm sieve. The quartz content of the sand was 80%. The particle size distribution of the limestone crushed stone was as follows: 15% passed through a 0.125 mm sieve, 32% passed through a 0.250 mm sieve, 50% passed through a 0.5 mm sieve, 75% passed through a 1.0 mm sieve and 100% passed through a 2.0 mm sieve.

li 7 64934 The technical characteristics of the white sand-lime brick thus made were determined:

Density 2050 kg / m

Water absorption 10.5% 2

Compression strength 52.3 MN / m

Whiteness 70.2 of the whiteness of the MgO control

Frost resistance Meets the requirements of SFS standard 2803, ie withstands 25 thawing and freezing operations without breaking

Example 3

The lime sand brick according to the invention was made with the following pulp composition:

Lime 12%

Natural sand 38%

Crushed limestone 50%

The bricks were prepared in the same manner as in Example 1 and their properties were determined:

Density 1850 kg / m3

Water absorption 13.5% 2

Compressive strength 25.4 MN / m

Whiteness 71.0% of the whiteness of MgO

Frost resistance Meets the requirements of SFS standard 2803.

The grain distribution of the natural sand used was: 50% passed through a 0.63 mm sieve, 75% passed through a 0.125 mm sieve and 100% passed through a 0.250 mm sieve. The quartz content of the sand was 77%. The particle size distribution of the limestone crushed stone was: 10% passed through a 0.125 mm sieve, 18% 0.25 mm, 30% 0.5 mm, 46% 1.0 mm, 62% 2.0 mm, 82 % 4.0 mm and 100% 8.0 mm sieve.

The corresponding technical characteristics of standard industrial lime sand brick according to SFS standard 2803 are: 64934 8

Density 1900 kg / m 2

Water absorption 12.3% 2

Compressive strength 23.5 MN / m

Whiteness 63.1% of the whiteness of MgO

Frost resistance Meets the requirements of standard SFS 2803.

The composition of a standard sand-lime brick is as follows:

Lime with act. CaiOH) content 91% 12%

Natural sand 88%

The SiO2 content of natural sand is 78%. The grain distribution of the sand is essentially as described above.

The whiteness measurement was also performed on a known light facade brick made of crushed quartz. The SiO 2 content of the quartz was 90%. The value was 64.5% of the whiteness of MgO. Thus, according to the measurements, the white sand-lime brick produced according to the invention is more than 5 percentage points lighter than the products obtained by previous manufacturing methods. The difference in whiteness is also clearly noticeable visually.

The examples described above show that bricks with enhanced whiteness that meet the technical quality requirements can be produced by deviating significantly from conventional lime sand brick production. Essential in this case is that the visually accentuated white color is mainly given by the white, non-reactive crystalline, light-reflecting limestone crushed stone used as the stone filler and aggregate. It is clear that the mixture ratios mentioned in the examples can be deviated considerably within the scope of the following claim and thus lime-sand lime with different whiteness can be obtained.

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