SE450378B - Lime sand tile with elevated visual whiteness effect as well as a process for making the tile - Google Patents

Description

450 378 2 for the production of the currently marketed limestone sandstones. It has now surprisingly been found that white limestone sand bricks can be produced by completely deviating from the usual production method for limestone sand bricks by using as the main raw material for the brick mass an inert, crystalline limestone crusher, which does not participate in the formation of the brick binder body. and natural quartz sand. This has been made possible by the fact that the binder can arise in an optimized reaction between specially optimized components, finely divided quartz-containing natural sand and lime, Ca (OH) 2, whereby the stone's binder body consists of calcium hydrosilicate evenly distributed in the mass. The main part of the pulp volume, however, consists of a white filler, which gives a visually increased whitening effect to the brick for both a smooth and a split brick.

It is known to use limestone as a filler in curable matrixes. Among other things, it is known from before to mix limestone in a matrix for concrete pipes. Lime-sand bricks have also previously used natural-colored stone filler to achieve an aesthetic effect. However, hitherto known fillers are normally those which react with the matrix. This is necessary in order to achieve a strength value that corresponds to the standards for the finished product.

Lime sand bricks have also been produced, where the grain size of the stone substance was 5-8 mm. However, the rock substance also contains SiO2, which is why it is not inert, since rock substances that contain SiO2 are inert only when their grain size is 10 mm and above.

The filler and element in the brick is crystalline.

As this substance does not react with the binder used, its surfaces remain unchanged, which increases the light reflection factor of the tiles. In this way a considerable visual effect is obtained, ie an emphasis on whiteness. 578 3 In order to give a clear account of the differences between the new production method and the known process for the production of lime sand bricks, the known process and substances used in this process are compared below with the process according to the invention and substances used therein, especially in the production of white lime sand bricks. Known lime sand bricks are made from quicklime, quartz sand and water. The aforesaid substances are mixed with each other to a moist mass, whereby the lime is quenched to calcium hydroxide, Ca (OH) 2. The pulp is pressed with high pressure, 20-30 MN / m2, to raw bricks, which are treated at 1.2 ~ 1.8 Ma vapor pressure in an autoclave, the lime, Ca (OH) 2, quartz sand, SiO2, and the water, H2O, reacts with each other to form the binder of lime sandstone, calcium hydrosilicate, CHS.

The dry matter of the pulp in a conventional lime-sand brick consists of 8-12% lime, Ca (OH) 2 and 92 ~ 88% quartz sand. The SiO2 content of quartz sand should be at least 70-75% and likewise the grain distribution of the sand used should be such that dense and solid bricks are formed during pressing. The porosity of the finished limestone sandstone should also be such that the stone is cold-resistant.

The porosity is affected by the grain distribution of the sand used, which should generally meet the following requirements: Grain size Transmission mm% <0.125 10- 30 <0.25O 30- 40 <0.5 '55- 65 <2.0 90-100 < 4.0 100 Known white calcareous sand bricks are produced according to the above principle and by using white crushed quartz sand, the SiO2 content of which generally exceeds 95%. 450 378 4.

In the process according to the invention for the production of white lime sand brick, the main raw materials are thus lime, fine natural quartz sand and a coarse white crushed body material of crystalline limestone.

The natural sand used should have approximately the following grain size distribution. Sieve size Transmission mm% 0.063 20- 60 0.125 60- 70 0.250 70- 90 0.50 90-100 In the white limestone sandstone prepared according to the invention, the main material of the body material is white crystalline limestone. which does not react with the lime during the autoclave treatment. Such a stone material is often more readily available and it is also cheaper than white crushed quartz sand. White inert limestone crusher is added to the brick mass in an amount of 70-30% depending on the desired color shade in the finished product.

The white stone material is significantly coarser than the natural quartz sand used in the binder. The binder's share of the lime sand mass is 30-60%. The binder consists of slaked finely divided lime, Ca (OH), whose specific surface area is greater than 1000 m2 / kg and whose proportion of the binder is 16-28%. The content of free SiO2 is greater than 75%. The specific surface area of quartz sand is 50-200 m2 / kg (Blaine). The binder contains sand in an amount of 86-72%.

The grain distribution of the white limestone crusher should be, for example, as stated below: | 1 450 578 Sieve size Transmission 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 In the following, the composition, preparation and properties of the white lime sand tile prepared according to the present invention are given in some examples: EXAMPLE 1 The raw materials were mixed together to form a homogeneous mass in the following ratio: Composition: Lime 14% Natural sand 43% Limestone crusher 43% In the mixture, water was added in an amount of% of the dry weight and it was pressed into bricks with MPa pressure. The rats were treated for 15 hours in an autoclave at 16 bar pressure.

The lime used was so-called industrial fine lime, whose active lime content, Ca (OH) 2 was 82.9%. The grain distribution of natural sand was: 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 natural sand was 85%. The grain distribution of the limestone crucible was: 15% passed through 0.125 mm sieve, 24% through 0.250 mm sieve, 35% through 0.5 mm sieve, 55% through 1.0 mm sieve, 78% through 2.0 mm sieve and 100%. % through 4.0 mm sieve. 41 :.

LH C 3 CN \ Z | CO 6 The following technical properties were determined for the limestone sandstone prepared as shown above: Tarnate 2020 kg / mf * Water suction force ll, l% Compressive strength 63.7 MN / m2 Whiteness 69.5% of the whiteness of an MgO reference piece Cold resistance meets the requirements according to SFS standard 2803, ie withstands 25 melts and cools without breaking. EXAMPLE 2 The raw materials were mixed together to form a homogeneous mass in the following ratio: Composition: Lime 12% Natural sand 38% Limestone crush 50% The toggle was prepared in the same way as in Example 1 and the following technical properties could be determined: Density 1800 kg / m3 Water suction power l4, l% Compressive strength 23.6 MN / m2 Vithct 71.0% of the whiteness of an MgO reference piece Cold resistance Meets the requirements according to SFS standard 2803.

The grain distribution of the natural sand was: 60% went through a 0.63 mm sieve, 88% through a 0.125 mm sieve and 100% through a 0.250 mm sieve. The quartz content of the sand last year was 88%. The grain distribution of the limestone crusher was: 10% p 450 578 7 went through a 0.125 mm sieve, 18% through a 0.25 mm sieve, 30% through a 0.5 mm sieve, 46% through a 1.0 mm sieve, 62% through a 2.0 mm screen, 82% through a 4.0 mm screen and 100% through an 8.0 mm screen.

The corresponding technical properties of a conventional, industrially produced lime sand brick according to SFS standard 2803 are as follows: Density 1900 kg / m3 Water suction power l2.3% Compressive strength 23.5 MN / m2 whiteness 63.1% of the whiteness of MgO Cold resistance Meets the requirements according to The SFS standard 2803 The composition of a lime sand brick according to the standard is as follows: Lime, whose content of activated lime, Ca (OH) 2, is 91% 12% Natural sand 88% The natural sand SiO2 content is 78%. The grain distribution of the sand is essentially the same as that shown above.

Whiteness measurement was also performed on a known facade brick made of crushed quartz. The SiO2 content of quartz was 90%. As a whiteness value, 64.5% of the whiteness of MgO was obtained. According to the measurements, a white lime sand brick produced according to the invention is thus over 5% units lighter than products obtained according to previous production methods. The difference in whiteness can be clearly discerned even with the naked eye.

The examples shown above show that bricks can be produced with an increased visual effect of whiteness and that meet high quality linings in a way that differs considerably from conventional lime sand brick production. In this case, it is essential that the enhanced visual effect of white color is obtained mainly from a white, which has been used as a filler and backbone and with the lime non-reacting crystal, light-reflecting limestone crusher. It is clear that the mixing ratios shown in the examples may vary within the scope of the following claims, whereby lime sand bricks with different whiteness can be obtained. dr

Claims (2)

10 15 20 25 450 378 PATENT REQUIREMENTS Lime sand brick with increased visual whiteness effect, consisting of a lime sand mass of lime and sand pressed into brick and pressed under pressure and whitening stone material, characterized in that the lime sand brick is made of a mass whose dry matter consists of 30-60% binder and the remainder crystalline, crushed, inert limestone, that the binder has been formed from 86-72% finely divided natural quartz sand with a free SiO2 content of higher than 75% and a specific surface area of so-zoo m2 / kg and the rest quenched, finely divided lime, Ca (OH) 2, with a specific surface area greater than 1000 mz / kg, so that the crystalline, crushed, inert limestone, which did not participate in the bonding process of the lime sand brick mass, gives the increased whiteness. Process for the production of lime-sand bricks with an increased visual whitening effect, by pressing and firing under pressure of a lime-sand brick mass whose dry matter consists of lime and sand and a whiteness-giving stone material, characterized in that the dry matter of the lime-sand brick mass is formed by 30-60% binder the residue crystalline, crushed, inert limestone, the binder being formed from 86-72% finely divided natural quartz sand with a free SiO2 content of more than 75% and with a specific surface area of 50-200 m2 / kg and the residue quenched, finely divided lime, Ca ( OH) 2, with a specific surface area greater than 1000 m2 / kg.