Combined bioadditive for cement composites

Abstract

FIELD: building materials.SUBSTANCE: invention relates to additives for cement mortars, and can be used in the production of building mortars and concrete elements of concrete buildings. A combined bioadditive for cement composites consists of a mixture of granules with Bacillus licheniformis and Bacillus subtilis bacteria in a 1:2 ratio, produced using a 2.5% solution of calcium alginate, urea and microsilica, with the following ratio of components, wt.%: granules with Bacillus licheniformis and Bacillus subtilis bacteria 20-25; urea 20-30; the rest is microsilica.EFFECT: increasing the strength of concrete, increasing frost resistance, and reducing water absorption, which will reduce the corrosion of concrete and reinforced concrete and extend the service life of concrete products.1 cl, 1 tbl

Description

[0001] This invention relates to building materials, specifically to additives for concrete mixtures used to produce high-strength building materials, and can be used in the manufacture of structures and products, both in industrial construction and for the construction of residential and industrial buildings. The invention can also be used to prepare cement mortars for repairing cracks in concrete and cement composites.

[0002] It is known to obtain bioadditives from bacteria of the species Bacillus subtilis, Sporosarcina pasteuriie, Sporosarcina pasteurii, incorporated using pumice and zeolite (Self-healing concrete modified with a microbiological additive: dissertation of a candidate of technical sciences: 05.23.05 / Al Dulaimi Salman Davud Salman; [Place of protection: Russian University of Transport]. - Moscow, 2019. - 310 p.: ill.). However, when using these biological additives, the strength gain period of cement mortars was 90 days, which is a longer period of time compared to the proposed method.

[0003] Also known is the composition of a three-component additive for self-healing of concrete cracks consisting of granules with Bacillus subtilis bacteria, calcium lactate, metakaolin, etc. (Patent No. 2812225 C1 Russian Federation, IPC C04B 28 / 00. Three-component additive for self-healing of concrete cracks: No. 2023112126: declared 11.05.2023: published 25.01.2024 / K.A. Gorbachevsky, T.N. Chernykh, M.V. Komelkova, V.I. Vakilov; applicant Federal State Autonomous Educational Institution of Higher Education ''South Ural State University). A special feature of the use of this additive is the use of an additional plasticizer based on naphthalene sulfoformaldehyde, and the introduction of the additive was carried out throughout the entire mass of concrete, which is impossible to ensure when repairing already constructed objects.

[0004] Also known is the composition of a bioadditive for cement mortars, including the microorganism Bacillus cereus and a silica-containing component fired at a temperature of 400°C for 2 hours, dehydrated natural opoka with a specific surface area of ​​350-400 m 2 / kg at the following ratio of components, wt. %: microorganism of the species Bacillus cereus 35-40% and flask 60-65% (Patent No. 2773751 C1 Russian Federation, IPC C04B 28 / 02, C04B 14 / 04, C04B 24 / 00. Bioadditive for building mortars and fine-grained concrete: No. 2021106588: declared 12.03.2021: published 10.06.2022 / V. A. Beregovoy, A. E. Kapustin, S. A. Boldyrev [et al.]; applicant Federal State Budgetary Educational Institution of Higher Education ''Penza State University of Architecture and Construction''). However, there is no data on the possibility of storing the bioadditive over time.

[0005] The closest technological solution to the claimed one is a method for producing hybrid organomineral microcapsules for concrete mixtures and building mortars (Turobova M.A., Danilov V.E., Aizenshtadt A.M., Morozova M.V., Garamov G.A.; Federal State Autonomous Educational Institution of Higher Education “Northern (Arctic) Federal University named after M.V. Lomonosov”. Russian Federation Patent No. 2 756 655, IPC C04 B 16 / 00. No. 2020138930; Claimed 27.11.2020; Published 04.10.2021, BulletinNo. 28), which involves mixing a finely dispersed mixture of an active pozzolanic additive, which is a saponite-containing material with an average particle size of at least 200 nm and no more than 400 nm, with mechanically activated lime of comparable fineness and a biodegradable polymer. Cellulose acetates are used as the biodegradable polymer binder. The mixture is stirred and then held for 20 minutes until complete polymerization, followed by grinding to a particle size of no more than 1 μm. However, this method requires maintaining a constant high humidity to hydrate the additive components and form calcium hydrosilicates.

[0006] The technical effect is to increase the strength of concrete, increase frost resistance, reduce water absorption, which will reduce the corrosion of concrete and reinforced concrete and extend the service life of concrete products.

[0007] The technical task and result of the proposed invention is to develop a dry construction bioadditive for concrete, including granules with Bacillus licheniformis and Bacillus Subtilis bacteria in a ratio of 1:2, urea and microsilica, manufactured using a 2.5% solution of calcium alginate, wt. %: granules with Bacillus licheniformis and Bacillus Subtilis bacteria - 20-25, urea - 20-30, microsilica - the rest, and having the ability to increase frost resistance, reduce water absorption and increase the strength of a concrete product.

[0008] The essence of the invention lies in the fact that a dry construction bioadditive for concrete, consisting of a mixture of granules with Bacillus licheniformis and Bacillus Subtilis bacteria in a ratio of 1:2, made using a 2.5% solution of calcium alginate, urea and microsilica, with the following ratio of components, mass. %: granules with Bacillus licheniformis and Bacillus Subtilis bacteria - 20; urea - 20; microsilica - the rest, is mixed with concrete solutions. A feature of using this pair of strains of microorganisms of the genus Bacillus is that they have urease activity and are able to increase the lifespan of each other due to the release of additional microbial products, and the Bacillus licheniformis strain is able to transpose ammonia during the process of strengthening concrete due to its high ability to regulate nitrogen metabolism.

[0009] Granules with bacteria are obtained as follows: individual strains of Bacillus licheniformis bacteria are pre-cultivated in a fermenter on a synthetic nutrient medium from meat-peptone broth and Bacillus Subtilis on a synthetic Christensen nutrient medium with the addition of urea for 24-36 hours at a temperature of 38°C in a shaking mode (140-160 rpm).

[0010] To obtain a culture fluid, the bacterial strains Bacillus licheniformis and Bacillus Subtilis are mixed in a ratio of 1:2 to obtain a homogeneous bacterial culture with a total bacterial concentration of at least 10.

[0011] Next, the bacterial culture is immobilized with calcium alginate. The resulting mass is cooled and crushed by extrusion to a size of 0.5-1.0 mm, then mixed with urea and microsilica in the appropriate proportions. The mixture is then ready for use as a dry construction bioadditive for concrete. It increases strength and frost resistance, reduces water absorption, and thus reduces corrosion of concrete and reinforced concrete and extends the service life of concrete products.

[0012] For use, the mixture is added to concrete mortar, activating the granules and forming a building product.

[0013] The shelf life of the dry construction bioadditive is at least 3 years. The concentration of bacteria in the dry construction bioadditive for concrete is at least 10 6 cells / ml at the end of the expiration date.

[0014] Example 1. Dry construction bioadditive for concrete, containing granules with bacteria, containing Bacillus licheniformis and Bacillus Subtilis bacteria in a ratio of 1:2, produced using a 2.5% solution of calcium alginate, urea and microsilica, with the following ratio of components, mass. %: granules with Bacillus licheniformis and Bacillus Subtilis bacteria - 22; urea - 25; microsilica - the rest, is added to the concrete solution and mixed. Then, concrete samples were formed and kept under normal conditions for 28 days. After this time, compressive strength (MPa) was determined, and frost resistance and water resistance were also assessed. A blank test was also conducted, a concrete sample was subjected to load, but dry construction bioadditive was not used.

[0015] The test results are shown in Table 1.

[0016] Example 2. Dry construction bioadditive for concrete, containing granules with bacteria, containing Bacillus licheniformis and Bacillus Subtilis bacteria in a ratio of 1:2, manufactured using a 2.5% solution of calcium alginate, urea and microsilica, with the following ratio of components, mass. %: granules with Bacillus licheniformis and Bacillus Subtilis bacteria - 19; urea - 22; microsilica - the rest, then similar to Example 1.

[0017] The test results are shown in Table 1.

[0018] Example 3. Dry construction bioadditive for concrete, containing granules with bacteria, containing Bacillus licheniformis and Bacillus Subtilis bacteria in a ratio of 1:2, manufactured using a 2.5% solution of calcium alginate, urea and microsilica, with the following ratio of components, mass. %: granules with Bacillus licheniformis and Bacillus Subtilis bacteria - 26; urea - 22; microsilica - the rest, then similar to Example 1.

[0019] The test results are shown in Table 1.

[0020] Example 4. Dry construction bioadditive for concrete, containing granules with bacteria, containing Bacillus licheniformis and Bacillus Subtilis bacteria in a ratio of 1:2, manufactured using a 2.5% solution of calcium alginate, urea and microsilica, with the following ratio of components, mass. %: granules with Bacillus licheniformis and Bacillus Subtilis bacteria - 22; urea - 19; microsilica - the rest, then similar to Example 1.

[0021] The test results are shown in Table 1.

[0022] Example 5. Dry construction bioadditive for concrete, containing granules with bacteria, containing Bacillus licheniformis and Bacillus Subtilis bacteria in a ratio of 1:2, manufactured using a 2.5% solution of calcium alginate, urea and microsilica, with the following ratio of components, mass. %: granules with Bacillus licheniformis and Bacillus Subtilis bacteria - 22; urea - 32; microsilica - the rest, then similar to Example 1.

[0023] The test results are shown in Table 1.

[0024] Example 6. A dry construction bioadditive for concrete containing granules with bacteria, containing Bacillus licheniformis and Bacillus Subtilis bacteria in a 1:1 ratio, manufactured using a 2.5% solution of calcium alginate, urea and microsilica, with the following ratio of components, mass. %: granules with Bacillus licheniformis and Bacillus Subtilis bacteria - 22; urea - 25; microsilica - the rest, then similar to Example 1.

[0025] The test results are shown in Table 1.

[0026] Example 7. A dry construction bioadditive for concrete containing granules with bacteria, containing Bacillus licheniformis and Bacillus Subtilis bacteria in a ratio of 2:1, manufactured using a 2.5% solution of calcium alginate, urea and microsilica, with the following ratio of components, mass. %: granules with Bacillus licheniformis and Bacillus Subtilis bacteria - 22; urea - 25; microsilica - the rest, then similar to Example 1.

[0027] The test results are shown in Table 1.

[0028] Example 8. Dry construction bioadditive for concrete, containing granules with bacteria, containing Bacillus licheniformis and Bacillus Subtilis bacteria in a ratio of 1:2, produced using a 2% solution of calcium alginate, urea and microsilica, with the following ratio of components, mass. %: granules with Bacillus licheniformis and Bacillus Subtilis bacteria - 22; urea - 25; microsilica - the rest. Granules are not formed.

[0029] Example 9. Dry construction bioadditive for concrete, containing granules with bacteria, containing Bacillus licheniformis and Bacillus Subtilis bacteria in a ratio of 1:2, produced using a 6% solution of calcium alginate, urea and microsilica, with the following ratio of components, by weight %: granules with Bacillus licheniformis and Bacillus Subtilis bacteria - 22; urea - 25; microsilica - the rest. The resulting mass for extrusion is rigid, the granules are not formed.