CS257142B1 - Cement blend with a hardened increase in strength - Google Patents

Abstract

The solution deals with a cement mixture with an accelerated increase in strength. Its essence is that, in addition to cement and possibly water and/or fillers and/or known additives and/or admixtures, it contains, based on the weight of the cement, 0!.1 to 12% by weight of a mixture of calcined aluminum sulfate* and basic aluminum sulfates, while the molar ratio of aluminum oxide AI2O3 to sulfur oxide SO3 in the mixture is from 1:0;.5 to 1 : : 2.95. The cement mixture of the solution platform is used for the production of cement slurries, mortars, injection mixtures and concretes, preferably wherever a rapid increase in initial strengths is required, at various hardening temperatures ranging from low to negative temperatures during winter work to elevated temperatures used to accelerate the hardening of concrete in pre-fabricated concrete.

Description

257142

The present invention relates to a cementitious compound with an accelerated increase in strength in which Portland clinker-based cement is used as a binder.

Construction practice urgently needs cement mixtures, such as cementitious mortars, injection mixtures and concretes with accelerated rupture strength at normal temperatures, to accelerate hardening by pre-fabrication in both pre-fabrication and concreting and zolemol. prefabricated prefabricated concrete structures! in the winter conditions. For all these purposes, cementitious compositions containing calcium admixture have best been proven to date. However, calcium chloride provides corrosion of both steel reinforcement and steel links, and is therefore not used in reinforced concrete structures. Mixtures containing 60 to 95 parts by weight of Portland cement, 2 to 20 parts by weight of calcium sulfate, 5 to 30 parts by weight of aluminous cement and 0.2 to 5 parts by weight of sulfonated product are known from DOS 2 356 636 the condensation of amino-s-triazine with formaldehyde, which is essentially a sulfonated amine-formaldehyde resin, produced by Suddeutsche Kalkstickstoffwerke, Germany with the commercial designation Melment F 10 or Melment L 10. therefore, it is not suitable for the usual techniques of processing cement mortars. If sodium transodium is used instead of calcium sulphate in the mixture of DOS 2 356 637, the pot life of the cementitious mixture is somewhat prolonged, but this elongation is also not sufficient to process them in conventional technological times; however, a more rapid increase in strength is achieved only at the initial stage of hardening of the cementitious mixture accelerated by overheating, in such a low range of strengths that are insufficient to remove and transport the prefabricated components.

The addition of alumina cement to Portland cement gives rise to a negative increase in strength after prolonged overheating times required to achieve the necessary handling strengths of the prefabricates. The addition of alumina cement also has a negative effect on the long-term stability of the cement stone structure and hence the physical-mechanical properties of the concrete. The negative effect of the addition of aluminate cement to Portland cement is thus more pronounced, the higher the amount of aluminate cement and the longer the time for the cementitious composition has elapsed. In the case of accelerating the hardening of cementitious mixtures, the negative effect of the addition of aluminate cement is further emphasized by the longer the residence time of the cement mixture before the start of over-heating, and the longer the over-heating time. Also known are cementitious compositions containing S. Bechyne aluminum sulphate additive: Concrete Technology, Volume 1 - Concrete Components, SNTL Praha 1954, p. 581). In the fresh state, the cementitious mixtures with the addition of aluminum sulphate imitate false solidification (A.Joisel: Admixtures for cement. Published by Soisy, France, 1973, p. 127), making it practically impossible to utilize them for fast curing and strength increase. For example, the solubility of aluminum sulphate containing crystalline water [eg, octadecahydrate A12 (SO4) 3.18 H-, O-, or duodecahydrate A12 (SO4) 3.12 * Η2Ο] is good, so that all aluminum sulphate can react immediately to the addition water. 's cemen-tom. In the technical literature, there are disclosed compositions containing various combinations of aluminum sulphate with other known additives, for example plasticizing, hydrophobizing and the like. However, the rapid dissolution of the aluminum sulfate causes false solidification even in the combinations mentioned.

The aforementioned disadvantages are eliminated by the cementitious compound with accelerated increase of strength AO USSR 223 134, characterized in that it contains, based on the weight of the cement, 0.2 to 10% by weight of incompletely calcined aluminum sulphate with a residual water content of 0, 1 to 20% by weight and containing at least 50% by weight of particles less than 90 μηα and at least 30% by weight of particles smaller than 63 μ.

It has been surprising to find that further improvement is achieved in the cementitious composition of the invention. It is based on the fact that, in addition to water and / or fillers and / or known modifying additives or additives, it contains, based on the weight of the cement, 0.1 to 12% by weight of a mixture of calcined aluminum sulphate and basic aluminum sulphates, wherein the molar ratio of SO3 to SO2O3 in the mixture is from 1: 0.5 to 1: 2.95.

As Portland Portland cement, for example, portland, trotland, or pozzolan portland cement can be used in the cementitious composition of the present invention.

As known additives, for example, silica sand, carbon fiber, river gravel, optionally expanded fillers, such as expanded clay or expanded polystyrene, can be used.

As known ingredients, for example, ground or untreated fly ash, quartz fly, resulting from the production of silicon or ferro-silicon or fine milled pellets can be used.

For example, the following are known additives: - plasticizers, such as condensation products of (naphthalenesulfonic acid) with formaldehyde, or salts of lignosulfonic acid 257142 - aerating additives such as salts of abietic acid or sulfonated or sulphonated salts. fused fatty alcohols - retention additives, such as water-soluble cellulose derivatives - dispersions of polymers such as monomeric, binary or ternary dispersions - antifreeze agents such as calcium formate and sodium nitrate or urea - gasifying additives, such as aluminum powder - solidification regulators such as gypsum - additives of inorganic salts such as sodium aluminum, sodium carbonate - hydrophobic additives such as stearate or other insoluble fatty acids and the like, wherein the individual ingredients or combinations thereof are selected according to the need and purpose of using cementitious compositions of the invention. The following examples show the advantages of the cementitious composition according to the invention. Example 1

The following materials were used for the tests: - Portland cement of class PC 400 - Known ingredient based on incompletely calcined aluminum sulphate produced by following procedure: 1000 g of commercially produced granular aluminum sulphate containing 15crystalline waters, containing 558, 72 g of dry matter and 44,128% of water, calcined for 18 hours at 200 ° C + 2 ° C. The calcination residue was 614.59 g, thus containing 10% residual water. The dried product was crushed to a content of less than 50%

Table 1 weight particles smaller than 90 and less than 30% by weight less than 63 μΐη.

The molar ratio of alumina A13O3 to SO3 in this product was 1: 3. The product was designated Example A. - Additive labeled C to the cementitious composition of the invention, obtained by annealing 300 grams of incompletely calcined and ground aluminum sulphate 10% water. The annealing was carried out at 600 ° C for 5 hours. The remainder of the annealing was 210 g, because the removal of sulfur trioxide (H. Remy: Inorganic Chemistry I, SNTL Praha 1961, p. 372) also occurred due to the loss of residual water. . Thereby, the molybdenum oxide is converted to SO3. changed 1: 2,367. However, no free oxide or aluminum hydroxide was detected in this product by X-ray analysis. Annealing was a calcined mixture? sulphate and basic aluminum sulphates. Of these materials, cement slurries were produced with batches of 2% by weight of cement adhering to a constant cement + additive ratio of fresh cement slurries b: 20 mm fused test cats that were cured in air 20 ° C and 90% relative humidity. Cattle samples were catalyzed after 18 hours. A compressive strength is tested for a portion of the samples after 18 to 24 hours, and other test samples are stored in water, and after 23 days their compressive strength has also been tested. The results are shown in Table 1 below.

Compressive strengths of hardened cement slurries with 2% additives

Type of porridge Ingredient

Comparative Without Additives -

According to AO 223 134 A

According to the invention C The results in Table 1 show that the cementitious composition according to the invention has an accelerated increase in strength not only of the additive slurry but also of the slurry with a known A label.

Compressive strength MPa after 18 hrs 24 hrs 28 days 5.0 6.4 «· 56.4 10.65 13.25 56.9 13.30 14.80 57.5 Example 2

Of the Trc-Portland SPC 325 cement, the standard sand of CSN 72 2117, the additive C of Example 1, the quartz formation of ferro-silicon and

Claims (3)

257142 8 a plasticizing agent based on sulfonated melamine formaldehyde resin of the Authentication Certificate stage 181 904 (see, for example, S Slaniček: Use of APV additives in practice, Civil Engineering, 24, No. 8--9 // 1970, p. 415—417 ) Standard mortars produced by the procedure according to the standard ČSN 72 2117. T a 2 The composition of mortars, their processing capacity as measured by the spillage of CSN 72 2441 (ie according to Haegermann), as well as the measured tensile strength under bending and compression after 24 hours and after 28 parts, are given in on-table 2. Composition, workability and strength of mortars according to ČSN 72 2117 Type 1) Doses of additives in% by weight. Strength of MPa Mortar Spreading of cement21 after 24 hours after 28 days mm "c" Si Plastifi-pull under Pressure Stroke by Tla. 1 drift drilling3 * bending bend Comparison 162 - - - 1.8 6.9 6.4 35.6 No additives According to the specification 200 2 0.5 4.0 16.4 8.0 37.2 S dou C and · plasticizer with additive C, 170 2 10 0.5 3.8 15.6 9.1 44.0 aplastif. Note: 1) Mortars hurt and spilled at constant rate v / c ---- = 0.5, required by CSN 72 2117. For mortars with additives, this ratio was maintained as cement + additives. ) Additives hurt dosed in% by weight as a replacement, so the sum (cement - additive) was constant everywhere. 3) AO 181904 plastic stage additive was dosed as dry matter additive cement. The results shown in Table 2 show that the highest initial and final strengths were achieved in the mortars according to the invention. However, the examples are not intended to limit the scope of the various optional additives or additives or their combinations in the cementitious composition of the present invention. Further useful uses of the cementitious composition according to the invention are, for example, mixtures containing, in addition to a mixture of calcined sulphate and basic aluminum sulphate, antifreeze additives such as carboxyldiamide, optionally soluble salts of formic acid and nitrates, which are most suitable for providing cement hydration. low to negative hardening temperatures, or dry prefabricated dry spray mixtures, which may also be supplemented by other u-accelerating additives, for example, industrial sodium alumina intermediates which are formed as an intermediate in the manufacture of of alumina from bauxite. The cementitious composition of the present invention is particularly advantageous when it is desired to accelerate the increase in initial strength, including those where over-heating is used to accelerate curing. OBJECT Cement blend with accelerated growth, consisting of. from cement to baseportland clinker and optionally water and / or filler and / or known admixtures and / or known additives, characterized in that it contains, based on the weight of the composition, 0.1 to 12% by weight of the calcium- of new aluminum sulphate and basic aluminum sulphates wherein the molar ratio of aluminum oxide A12O3 to SO3 SO3 is from 1: 0.5 to 1: 2.95. Severografia, n. P. Plant 7, Most Price 2,40 Kcs