CS273229B1 - Gypsum-free solid mixture on base of ground clinker - Google Patents

Abstract

The invention concerns a gypsum-free solid mixture on a base of ground clinker, which is used in construction in special applications requiring short and long-term rigidity. The mixture contains Portland or white cement clinker on a medium surface of 300 to 700 m<2>/kg, a grinding additive, sulphonated polyelectrolyte, alkaline metal salt, filler, very fine amorphous SiO2, mixing water and a hardening regulator. The essence is that the filler contains 96 % by weight particles with grain size of 0.5 to 22 mm, whereas the number of shares of grain with diameter less than 0.5 mm and larger than 22 mm is 4 % by weight of the filler.

Description

The invention relates to a solid composition wherein a gypsum-free Portland cement is used as a binder.

Gypsum-free Portland cement - BS cement - is a new type of inorganic binder. This binder is based on Portland or white cement clinker ground to a specific surface of 300 to 700 m ² / kg. Gypsum, which is a common regulating additive in Portland cement, is replaced by a synergistic mixture of sulfonated polyelectrolyte, e.g. , KHCQ3, and sodium or potassium silicates with different silicate modulus.

BS cement differs in some properties and in the course of hydration from conventional Portland - gypsum cement. The properties of BS cements were previously described in US Pat. No. 3,689,294, U.S. Pat. No. 4,168,985, U.S. Pat. No. 4,551,176, and then in U.S. Pat. No. 253,499, 257,315, 270,602 and 273,201.

A distinctive feature of BS cements is the possibility of their processing at low water coefficient without loss of good workability and achievement of high short- and long-term strengths. These properties give the possibility to use BS cements especially for special applications.

The disadvantage of BS cement mortars and concretes prepared from common building sand and aggregates is that their strengths often do not reach the values achieved by these cement cements. In connection with the solution of the problem of achieving high strengths of BS cement mortars and concretes, there are some limitations that result in achieving only lower strengths and impairing the workability of the mixtures. These are primarily technological macropores - of the order of 10 to 10 ² / µm - given by aeration of mixtures. This macroporosity has a closed spherical character in BS cements and there is no open capillary porosity to the extent characteristic of Portland cement concretes. However, this technological micro-porosity in BS cement mortars and concretes causes only a fraction of the attainable strength to be achieved, especially in the flexural tensile strength. Birchall, Kendall and Howard pointed out these effects of technological macropores in EP 30,408. By removing the macropores, they, together with the application of polymers, resulted in materials with a tensile strength of up to 150 MPa for MDF cements. Removal of technological macropores is possible to a large extent in BS cement mixtures using antifoaming agents, for example 2-ethylhexanol, tributyl phosphate or SiOg + silicon dioxide drift.

A further limitation is the composition and properties of the filler. The experimental results show that the workability of BS cement mixtures at low water coefficients significantly influences the content of fine fraction of fillers. These fine fractions further bind gypsum-replacing additives and cause a significant shortening of the onset of solidification.

The above-mentioned drawbacks are eliminated by a gypsum-free, ground clinker-based solid mixture containing Portland or white cement clinker ground to a specific surface area of 300 to 700 m ² / kg, a grinding additive such as ethylene glycol, triethanolamine, sulfonic acid alkalolamide and sulfonated polyelectrolyte. , such as ligninsulfonate and derivatives thereof, sulfonated polyphenolate, sulfonated polycondensates, alkali metal salts, preferably carbonate, bicarbonate or silicate, filler such as building sand, building aggregate, corundum, crushed clinker, crushed quartz, quartz sand, crushed granite , crushed limestone, crushed dolomite, pebbles, further highly amorphous SiOg, mixing water and solidification regulators of gypsum-free cements such as hydroxyacid salts, phosphates, boric acid, monosaccharides and their oxidation products, further organosilicon substances with antifoaming effect y.

AND

CS 273 229 B1

The invention is based on the fact that the filler used contains 96% by weight of the filler. a grain size of 0.5 to 22 mm, preferably 0.5 to 14 mm, wherein the sum of the grain fractions of less than 0.5 mm and greater than 22 mm is 4% by weight.

The basic prerequisite for achieving high strengths of BS cement mortars is processing at low water coefficient w <0.30 - 0.35. Experimental works have shown that in order to achieve good workability at low water coefficient of the mixture, it is necessary to eliminate filler particles with a size of less than 0.5 mm and further limit the maximum grain size of the filler to 14-22 mm. In order to achieve good workability at low water coefficient, it is necessary to limit the content of fine sand fraction - as a whole - below the value calculated by conventional methods of concrete mix design and to increase the content of coarse fraction such as aggregates. In order to achieve a good workability of the mixtures and to achieve high strengths, it is often necessary to increase the cement content in the mixture above 400 to 450 kg / πν ^{3 of the} mixture.

The physical and chemical properties of the fillers also influence the properties of the mixtures. From the chemical point of view, the contact zone of the hardened putty with the filler is very important. From a physical point of view, it is important to respect the strength and modulus of elasticity, or uniformity of these properties in the individual filler fractions and also in the entire volume of the filler used when selecting aggregates and sand.

Suitable fillers for BS cement mixtures are, for example, coarse sand, coarse corundum sand, pebbles, crushed clinker, granite grit, microcrystalline limestone or dolomite, etc., although the use of conventional building sand and conventional coarse aggregate in the fractions of the invention is not excluded.

The invention then allows the preparation of high-strength BS-based cements with a low water coefficient using conventional and special technologies.

The invention is illustrated by the following examples, but is not limited thereto. Palentol is a sulfonated sodium ferric polyphenolate.

Example 1

Q

BS cement with a specific surface area of 690 m / kg was prepared from the simulation of the cement plant Hranice. 0.8% water and 1% sodium lignin sulphonate, partially devoid of monosaccharides. Mortars with w = 0.30 were prepared from this cement, from 3 fractions of standard quartz sand in different ratios, the cement: sand ratio was always 1 and 3 by weight. The mortar was always monitored for the beginning of setting and workability. Workability was assessed by measuring the grooved cone insertion depth for 30 s under constant load.

Table 1 Total surface area of sands calculated from the value of setting solidity workability, depth of mean grain size (m * ² ) (min) injection (divisions)

520

490

720

990

1260

1400

1580

1700

120 145 115 135 105 145 105 115 95 110 85 100 ALIGN! 80 ’ 70 60 75

CS 273 229 B1

The injection of 145 pieces corresponds to a moving to liquid consistency of the mortar and - moving to liquid;

The injection of 70 pieces corresponds to the plastic consistency of the mortar.

Example 2

For mortar preparation with w = 0.33 and wt. cement ratio; Sand 1: 3 was used by

BS cement with a specific surface area of 690 m / kg, which was prepared as in Example 1. As sand, construction sand which did not comply with SsN in terms of washable particle content - high clay content - was used. Two fractions were prepared from this sand:

up to 2.5 mm and 0.6 to 2.5 mm. When using a fraction of 0 to 2.5 mra, the start of mortar solidification was after 8 to 12 minutes, while the application of sand of the fraction of 0.6 to 2.5 mm extended the start of solidification to 25 to 30 minutes.

Example 3

BS cement was prepared from the clinker of the Štramberk cement plant by grinding to the specific surface p

470 m / kg with 0.05 wt. dodecylbenzenesulfonic acid triethanolamide.

From this cement a slurry with w = 0.25 of free-flowing consistency was prepared with additives of 1% by weight. soda and 0.8% Ralentol, calculated on dry weight basis. Mortars with a cement: sand weight ratio of 1: 3 'were prepared and the number of solidification was determined.

Table 2 mixture start setting cement + sand Vojkovice 0 to 6.3 mm 60 min cement + sand Vojkovice 2 to 8 mm 100 min cement- + sand Vojkovice 4 to 8 mm 190 min cement + sand Chržín 0 to 6.3 mm 80 min cement + sand Chržín 5 to 8 mm 190 min slurry 210 min

Example 4

BS cement was prepared from the clinker of the Štramberk cement plant by grinding to a specific surface of 480 m / kg with the addition of 0.1% by weight. ethylene glycol. Concretes of the same composition were prepared from said BS cement in two variants: variant 1 without fraction limitation below 0.5 mm and variant 2 with fraction limitation below 0.5 mm to less than 2% by weight. «.

Mixture: variant 1

BS cement: fine aggregate fraction 0 to 4 mm Sagittarius: coarse aggregate frakoe 8 to 16 mm Rejta = 1: 1,8: 2,21

Cement dose was 470 kg / m, water coefficient w = 0.28 additive: SiOg drift Nun 2% wt.

soda total 2.9 wt. adjusted according to chemical analysis of sand and aggregates due to their exchange capacity

Ralentol 0.8 wt.%, Ethyl silicate-40 0.01 wt.

The percentages are based on cement.

CS 273 229 B1 4

Mixture: variant 2

The composition of the mixture is the same as for variant 1, except that a fine aggregate fraction of 0.5 to 4 mm Sagittarius was used. Further, to achieve the same processability, it was necessary to reduce the water coefficient to w => 0.27.

Bodies of 150.150.150 mm were made from the mixtures and densified by vibration. The manufactured bodies were stored for 24 hours at 90-100% humidity and then at 50-65% humidity. 3 specimens were used for each test term. The onset of solidification of 3 months was determined by the degree of mobility of the mixture in the mold. The mixes had a very good workability, which would allow use for reinforced concrete.

Table 3

mixture the beginning of solidification strength 1 day under pressure for 3 days (MPa) 28 days 1. 22 minutes 29.2 61.8 68.7 2. (according to the invention) 40 minutes 39.0 72.0 80.1

Example 5

BS cement was prepared from the mica of the Štramberk cement plant by grinding to a specific surface of 480 m / kg with the addition of 0.1% by weight. ethylene glycol. A slurry of free-flowing consistency at w = 0.24 aa mass addition was prepared from this spirum. 1% soda and 0.4% Ralentol - calculated on dry weight basis. Mortars were prepared using crushed corundum as a filler. These mortars had the same composition of 1: 3.2 (w / w) and two variants were prepared, in the first variant this fraction was limited to a maximum content of up to 2% by weight. The mortars had the same consistency - plastic consistency.

Mixture variant 1. without limitation fraction below 0,5 mm composition cement + corundum fraction 0 to 1,5 mm 1,2 parts by weight

corundum frakoe 2 to 5 mm 2 parts by weight

water coefficient w = 0.275 additives: SiO ₂ drift Mníšek 2% wt. soda 1.4% by weight,

Ralentol 0.6 wt.%, Ethyl silicate-40 0.01 wt.

percentages are based on cement.

From the prepared mixtures, bodies with the dimensions of 40.40.160 mm were produced, which were subjected to the flexural strength and compressive strength test according to the principles given for these tests in ČSN 72 2117. The results of all tests are given in the following table.

CS 273 229 B1

Table 4 strength (MPa) day 3 days 7 days 28 days

bend pressure bend pressure bend pressure bend pressure porridge - 70.0 - - - 89.0 - 107.0 O no. 1 12 70 13 90 15 Dec 108 16 129 No.2 12 80 15 Dec 100 ALIGN! 18 115 20 May 152

(according to the invention)

The composition according to the invention can be advantageously used in the construction industry, in particular special applications where high concrete strength or some mortars are required.

Claims (1)

SUBJECT OF THE INVENTION Ground gypsum-free solid mixture, containing gypsum of Portland or white cement, ground to a specific surface of 300 to 700 m ^ / kg, grinding additive such as ethylene glycol, tritanolamine, sulfonated alkalolamide, further comprising a synergistic mixture of sulfonated polyelectrolyte such as ligninsulfonate and its derivatives, sulfonated polyphenolate, sulfonated polycondensates, alkali metal salts preferably carbonate, bicarbonate or silicate, filler such as building sand, building aggregate, corundum, crushed clinker, crushed quartz, quartz sand, crushed granite, crushed limestone, crushed dolomite, pebbles, highly amorphous SiOg, mixing water and solidification regulators of gypsum-free cements such as hydroxyacid salts, phosphates, boric acid, monosaccharides and their oxidation products, organosilicon and antifoam agents, characterized by: in that the filler used comprises 96 wt. % of particles having a grain size of 0.5 to 22 mm, preferably 0.5 to 14 mm, wherein the proportions of the grains having a diameter of less than 0.5 mm and greater than 22 mm are 4% by weight of the filler.