Functional building freshly mixed concrete and preparation method of prefabricated part of functional building freshly mixed concrete

Abstract

The invention belongs to the technical field of building engineering materials, and particularly relates to functional building fresh mixed concrete and a preparation method of a prefabricated component of the functional building fresh mixed concrete. The functional building fresh mixed concrete comprises Portland cement clinker, fly ash, gypsum powder, a silicon-based water-containing capsule, water, gravel, mixed sand and a water reducing agent, according to the invention, water is wrapped in the capsule, so that the capsule has more ideal dispersibility in a concrete system in the form of inorganic particles, and then water in the capsule is gradually released to participate in a hydration reaction, so that not only is the full degree of the hydration reaction in the whole concrete member ensured, but also the hydration uniformity is ensured; and the member can obtain higher mechanical strength.

Description

Technical Field

[0001] The invention belongs to the technical field of building engineering materials, and in particular relates to a method for preparing functional building fresh concrete and prefabricated components thereof. Background Art

[0002] Precast concrete components are precast components made by molding concrete in a factory in advance, and then transporting the precast components to the construction site and assembling them directly. Nowadays, they are playing an increasingly irreplaceable role in the construction industry, such as prefabricated buildings, decorative panels, road paving, bridge components, tunnel components, and water conservancy project components.

[0003] Precast concrete components are made of concrete. The raw materials of fresh concrete generally include water, cement, fly ash, gravel, sand, water reducing agent, etc. After these raw materials are mixed to obtain fresh concrete, the fresh concrete in a flowing state is poured into a mold for a certain period of curing and molding to obtain precast components. However, due to the unsatisfactory compatibility between water and the concrete matrix, it is difficult for water to be evenly distributed in fresh concrete. For example, the bleeding phenomenon that often occurs in fresh concrete affects the hydration reaction in the fresh concrete, which ultimately affects the strength of the formed concrete components. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a functional building fresh concrete, which comprises, by weight, 100 parts of Portland cement clinker, 5 to 15 parts of fly ash, 2 to 10 parts of gypsum powder, 15 to 30 parts of silicon-based water-containing capsules, 30 to 40 parts of water, 180 to 230 parts of crushed stone, 80 to 100 parts of mixed sand, and 0.5 to 2 parts of a water reducing agent.

[0005] Wherein, the preparation method of silicon-based water-containing capsule is:

[0006] A water-soluble alkali agent is dissolved in pure water to obtain an alkaline aqueous solution with a pH of 10 to 12, and then a quaternary ammonium salt cationic emulsifier is fully dispersed in the alkaline aqueous solution as an aqueous phase; the aqueous phase and an oil phase based on a water-insoluble organic solvent are mixed and fully dispersed in a mass ratio of 1:1 to 40 to obtain a mixed emulsion; after siloxane is fully dispersed in the mixed emulsion for a hydrolysis reaction, the solid component generated by the reaction is separated from the organic solvent to obtain a silicon-based water-containing capsule.

[0007] As a preference: the water-soluble alkaline agent is sodium hydroxide, potassium hydroxide, carbonate, bicarbonate, etc.;

[0008] Preferably, the weight ratio of the quaternary ammonium salt cationic emulsifier to the alkaline aqueous solution is 3 to 8:100;

[0009] Preferably, the oil phase further includes a non-ionic emulsifier, and the weight ratio of the non-ionic emulsifier to the organic solvent is 0.01-0.5:100;

[0010] Preferably, the weight ratio of the silicone to the mixed emulsion is 2-20:100;

[0011] Preferably, the hydrolysis reaction is carried out at 25°C to 70°C for 10 to 100 hours.

[0012] In the above preparation process, taking the water droplets emulsified and dispersed in the oil phase as a template, the silicone dissolved and dispersed in the organic solvent gradually undergoes a hydrolysis reaction on the oil-water interface of the template, and finally condenses to form an inorganic coating structure of Si-O-Si, thereby coating the water droplets serving as the template therein.

[0013] Preferably, in terms of composition, the Portland cement clinker includes 15-30 parts by weight of dicalcium silicate, 40-70 parts by weight of tricalcium silicate, 5-15 parts by weight of tricalcium aluminate, and 10-20 parts by weight of tetra-calcium aluminoferrite.

[0014] Preferably, the particle size of the crushed stone is 5-20 mm.

[0015] Preferably, the mixed sand includes fine sand with a particle size of 30-115 mesh and coarse sand with a particle size of 0.5-5 mm, and the weight ratio between the fine sand and the coarse sand is 1-1.5:1.

[0016] The present invention also provides a processing and preparation method for precast components based on the above-mentioned fresh functional building concrete: after mixing the above-mentioned Portland cement clinker, fly ash, gypsum powder, silicon-based water-containing capsules, water, crushed stone, mixed sand, and water reducer together, stirring at a rate of 60-120 revolutions per minute for 5-10 minutes, then pouring into a mold for curing and demolding to obtain precast components.

[0017] Preferably, during the pouring process, the mold is jolted to compact the mixture therein; after pouring, the opening at the top of the mold is leveled to remove the excess mixture; after entering the curing stage, too high a temperature will cause the components to burn out, too low a temperature will affect the hardening and quality of the components, and too fast a heating or cooling rate will cause internal stress in the concrete components, which is the biggest cause of component cracks. Therefore, the curing temperature needs to be strictly controlled. Specifically, after the mold filled with the mixture is left standing at room temperature in the curing box for 1.5-2 hours, the temperature in the curing box is steam-heated to 50-60°C at a heating rate of 8-12°C / hour, and after heat preservation curing for a period of time, when the temperature in the curing box naturally drops below 45°C, it is then cooled to room temperature at a cooling rate of 10-15°C / hour. During the cooling process, the relative humidity in the curing box needs to be controlled at 50%-60%. Too low humidity will cause the surface of the components to crack, and too high humidity will cause the components to deform.

[0018] The beneficial effects of the present invention are as follows: When concrete is formed into precast components by adding water, both natural water and silicon-based water-containing capsules are used as the hydration water for fresh concrete. Among them, a certain amount of natural water is added to the concrete mixing system, mainly to ensure the fluidity of the concrete system before casting, so as to facilitate construction pouring. Of course, this natural water will also participate in the hydration reaction of cement in the concrete; while the silicon-based water-containing capsules use inorganic silicon oxides generated by the hydrolysis of silicon sources as the capsule walls, and the water is wrapped therein, so that they are added to the fresh concrete system in the form of inorganic particles similar to building materials. Therefore, they have more ideal dispersibility in the concrete system with the same inorganic environment. When the silicon-based water-containing capsules are dispersed throughout the wet fresh concrete system, as the hydration reaction in the fresh concrete proceeds, while the concrete gradually hardens, the water in the concrete is gradually consumed due to participating in the hydration reaction. And because there are pore structures distributed on the walls of the silicon-based water-containing capsules, the water wrapped in the capsules can gradually migrate to the outside and continue to participate in the hydration reaction as a water supplement to ensure the degree of completion of the hydration reaction in the concrete and the service strength of the precast components after forming. Specific embodiments

[0019] Example 1

[0020] Sodium hydroxide is added to pure water to prepare a uniform alkaline aqueous solution with a pH of 10. Then, according to the weight ratio of dodecyltrimethylammonium bromide to the alkaline aqueous solution of 3:100, dodecyltrimethylammonium bromide is fully dispersed in the above alkaline aqueous solution as the aqueous phase;

[0021] According to the weight ratio of Tween-40 to cyclohexane of 0.2:100, Tween-40 is fully dispersed in cyclohexane as the oil phase;

[0022] Under a continuously stable stirring state, 20 parts by weight of the above aqueous phase is added dropwise to 280 parts by weight of the above oil phase. After the addition is completed, continue to stir until fully dispersed, then 20 parts by weight of tetramethoxysilane is added and dispersed fully. After heating to 40 °C and holding for 48 hours, the resulting reaction system is centrifuged to retain the precipitate (recover the organic solvent oil phase to reduce organic emissions, the same below), and the precipitate is spread out and left standing for 2 hours so that the organic solvent of the oil phase on its surface is basically volatilized, and then sealed and stored as the silicon-based water-containing capsule.

[0023] Preparation of fresh concrete and its precast components:

[0024] Mix 100 parts by weight of portland cement clinker (the weight ratio between dicalcium silicate, tricalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite is 25:55:7:13), 8 parts by weight of fly ash, 4 parts by weight of gypsum powder, 25 parts by weight of the silicon-based water-containing capsules prepared in this example, 40 parts by weight of water, 180 parts by weight of crushed stone, 50 parts by weight of fine sand, 35 parts by weight of coarse sand, and 2 parts by weight of polycarboxylate water reducer together, and then stir at a rate of 120 revolutions per minute for 10 minutes to obtain fresh concrete; then pour the fresh concrete into a mold. During the pouring process, shake the mold to compact the fresh concrete therein; after pouring, level the opening at the top of the mold to remove the excess fresh concrete; place the mold filled with the mixture in a curing box and let it stand at room temperature (25 °C, the same below) for 2 hours, then steam-heat the curing box to 50 °C at a heating rate of 8 °C per hour, and keep it under heat preservation for 2 hours (during this period, the temperature in the curing box is maintained at 50 - 60 °C), then remove the heat preservation measures. When the temperature in the curing box naturally drops below 45 °C, then cool it down to room temperature at a cooling rate of 10 °C per hour (during the cooling process, the relative humidity in the curing box needs to be controlled at 50% - 60%), demold, and use the demolded standard cube specimen with a side length of 150 mm as a precast member and continue to let it stand naturally in the factory building for 28 days.

[0025] Example 2

[0026] Preparation of fresh concrete and its precast members:

[0027] Mix 100 parts by weight of portland cement clinker (the weight ratio between dicalcium silicate, tricalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite is 27:48:15:10), 11 parts by weight of fly ash, 3 parts by weight of gypsum powder, 30 parts by weight of the silicon-based water-containing capsules prepared in Example 1, 35 parts by weight of water, 190 parts by weight of crushed stone, 45 parts by weight of fine sand, 40 parts by weight of coarse sand, and 2 parts by weight of polycarboxylate water reducer together, and then stir at a rate of 120 revolutions per minute for 10 minutes to obtain fresh concrete; then pour the fresh concrete into a mold. During the pouring process, shake the mold to compact the fresh concrete therein; after pouring, level the opening at the top of the mold to remove the excess fresh concrete; place the mold filled with the mixture in a curing box and let it stand at room temperature for 1.5 hours, then steam-heat the curing box to 52 °C at a heating rate of 10 °C per hour, and keep it under heat preservation for 2 hours (during this period, the temperature in the curing box is maintained at 52 - 60 °C), then remove the heat preservation measures. When the temperature in the curing box naturally drops below 45 °C, then cool it down to room temperature at a cooling rate of 10 °C per hour (during the cooling process, the relative humidity in the curing box needs to be controlled at 50% - 60%), demold, and use the demolded standard cube specimen with a side length of 150 mm as a precast member and continue to let it stand naturally in the factory building for 28 days.

[0028] Comparative Example 1

[0029] The silicon-based capsule wall material (equivalent to silicon dioxide particles) of the estimated silicon-based water-containing capsules and the water encapsulated therein were separately added to the freshly mixed concrete (i.e., at this time, the water in the silicon-based water-containing capsules was added to the freshly mixed concrete only in the form of natural water), and the other components and operations were the same as in Example 1:

[0030] Sodium hydroxide was added to pure water to prepare a uniform alkaline aqueous solution with a pH of 10. Then, according to the weight ratio of dodecyltrimethylammonium bromide to the alkaline aqueous solution of 3:100, dodecyltrimethylammonium bromide was fully dispersed in the above alkaline aqueous solution as the aqueous phase;

[0031] According to the weight ratio of Tween-40 to cyclohexane of 0.2:100, Tween-40 was fully dispersed in cyclohexane as the oil phase;

[0032] Under a continuously stable stirring state, 20 parts by weight of the above aqueous phase was added dropwise to 280 parts by weight of the above oil phase. After the addition was completed, stirring was continued until dispersion was sufficient, then 20 parts by weight of tetramethoxysilane was added and dispersed sufficiently, and the temperature was raised to 40 °C and kept for reaction for 48 hours. After centrifugal separation of the obtained reaction system, the precipitate was retained, and the precipitate was spread out and left in an 80 °C oven for 36 hours to be fully dried as the silicon-based capsule wall material.

[0033] Preparation of freshly mixed concrete and its precast components:

[0034] Mix 100 parts by weight of portland cement clinker (the weight ratio between dicalcium silicate, tricalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite is 25:55:7:13), 8 parts by weight of fly ash, 4 parts by weight of gypsum powder, 7 parts by weight of the silicon-based capsule wall material prepared in this comparative example, 58 parts by weight of water, 180 parts by weight of crushed stone, 50 parts by weight of fine sand, 35 parts by weight of coarse sand, and 2 parts by weight of polycarboxylate water reducer together, and then stir at a rate of 120 revolutions per minute for 10 minutes to obtain fresh concrete; then pour the fresh concrete into a mold. During the pouring process, shake the mold to compact the fresh concrete therein; after pouring, level the opening at the top of the mold to remove the excess fresh concrete; place the mold filled with the mixture in a curing box and let it stand at room temperature (25 °C, the same below) for 2 hours, then steam-heat the temperature in the curing box to 50 °C at a heating rate of 8 °C per hour, and keep it under heat preservation for 2 hours (during this period, the temperature in the curing box is maintained at 50 - 60 °C), then remove the heat preservation measures. When the temperature in the curing box naturally drops below 45 °C, then cool it down to room temperature at a cooling rate of 10 °C per hour (during the cooling process, it is necessary to control the relative humidity in the curing box at 50% - 60%), demold, and use the cube standard specimen with a side length of 150 mm after demolding as a precast component and continue to let it stand naturally in the factory for 28 days.

[0035] Comparative Example 2

[0036] Separate the silicon-based capsule wall material (equivalent to silicon dioxide particles) of the estimated silicon-based water-containing capsule and the water wrapped therein, and add them to the fresh concrete (that is, at this time, the water in the silicon-based water-containing capsule is only added to the fresh concrete in the form of natural water), and the other components and operations are the same as in Example 2:

[0037] Mix 100 parts by weight of portland cement clinker (the weight ratio between dicalcium silicate, tricalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite is 27:48:15:10), 11 parts by weight of fly ash, 3 parts by weight of gypsum powder, 8.5 parts by weight of the silicon-based capsule wall material prepared in Comparative Example 1, 56.5 parts by weight of water, 190 parts by weight of crushed stone, 40 parts by weight of fine sand, 45 parts by weight of coarse sand, and 2 parts by weight of polycarboxylate water reducer together, and then stir at a rate of 120 revolutions per minute for 10 minutes to obtain fresh concrete; then pour the fresh concrete into a mold. During the pouring process, shake the mold to compact the fresh concrete therein; after pouring, level the opening at the top of the mold to remove the excess fresh concrete; place the mold filled with the mixture in a curing box and let it stand at room temperature for 1.5 hours, then steam-heat the temperature in the curing box to 52°C at a heating rate of 10°C per hour, and keep it under heat preservation and curing for 2 hours (during which, the temperature in the curing box is maintained at 52 - 60°C), then remove the heat preservation measures. When the temperature in the curing box naturally drops below 45°C, cool it down to room temperature at a cooling rate of 10°C per hour (during the cooling process, it is necessary to control the relative humidity in the curing box at 50% - 60%), demold, and use the standard cube specimen with a side length of 150 mm after demolding as a precast component and continue to let it stand naturally in the factory building for 28 days.

[0038] Comparative Example 3

[0039] Replace the silicon-based water-containing capsules with the estimated corresponding amount of the silicon-based capsule wall material, and the other components and operations are the same as in Example 2:

[0040] Mix 100 parts by weight of portland cement clinker (weight ratio between dicalcium silicate, tricalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite is 27:48:15:10), 11 parts by weight of fly ash, 3 parts by weight of gypsum powder, 8.5 parts by weight of the silicon-based capsule wall material prepared in Comparative Example 1, 35 parts by weight of water, 190 parts by weight of crushed stone, 40 parts by weight of fine sand, 45 parts by weight of coarse sand, and 2 parts by weight of polycarboxylate water reducer together, and then stir at a rate of 120 revolutions per minute for 10 minutes to obtain fresh concrete; then pour the fresh concrete into a mold. During the pouring process, shake the mold to compact the fresh concrete inside; after pouring, level the opening at the top of the mold to remove the excess fresh concrete; place the mold filled with the mixture in a curing box and let it stand at room temperature for 1.5 hours, then steam-heat the temperature in the curing box to 52°C at a heating rate of 10°C per hour, and keep it under heat preservation for 2 hours (during this period, the temperature in the curing box is maintained at 52 - 60°C), then remove the heat preservation measures. When the temperature in the curing box naturally drops below 45°C, then cool it down to room temperature at a cooling rate of 10°C per hour (during the cooling process, the relative humidity in the curing box needs to be controlled at 50% - 60%), demold, and use the standard cube specimen with a side length of 150 mm after demolding as a precast component and continue to let it stand naturally in the factory for 28 days.

[0041] Before the fresh concrete obtained in each of the above examples and comparative examples is poured and cured, measure its slump; and test the compressive strength of the standard specimens of the precast components formed from each fresh concrete. The test results are shown in Table 1.

[0042] Table 1

[0043]

[0044] Among them, the detection operation of the "slump" is as follows: Place a regular trumpet-shaped slump bucket with an upper inner diameter (diameter) of 100 mm, a lower inner diameter (diameter) of 200 mm, and a vertical height of 300 mm vertically on the horizontal ground. Pour the freshly mixed concrete into the inner cavity of the bucket as evenly as possible in three times. After each pouring, use a tamper to tap the outer wall of the bucket circumferentially and evenly to make the freshly mixed concrete in the inner cavity fill and compact as fully as possible in the inner cavity of the bucket. After the last tapping, level the top of the bucket to remove the excess freshly mixed concrete at the top of the bucket. At this time, pull the bucket vertically upward. After the freshly mixed concrete loses the restricted support of the bucket, it collapses due to its own weight. After the collapse stabilizes, subtract the vertical height of the highest point of the freshly mixed concrete at this time from 300 mm (the stacking height of the freshly mixed concrete in the inner cavity of the bucket) to obtain the "initial slump"; after standing for 30 minutes, subtract the vertical height of the highest point of the freshly mixed concrete after standing from 300 mm to obtain the "slump after 30 minutes". The larger the slump, the stronger the fluidity of the freshly mixed concrete, and it is more convenient for pouring and processing;

[0045] The detection of the "compressive strength" is carried out in accordance with the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" GB / T 50081-2002.

[0046] Judging from Table 1, the components formed by the freshly mixed concrete in each example are significantly superior in mechanical properties to the corresponding Comparative Examples 1 and 2. This is because after all the water is directly added to the concrete system in Comparative Examples 1 and 2, these waters cannot be dispersed too evenly therein, resulting in insufficient degree of hydration in some areas inside the concrete, while in some areas, due to excessive water aggregation, these waters will leave obvious holes in the concrete member after hydration or evaporation, which all affect the overall mechanical strength of the member; while in the examples based on this solution, a part of the water is wrapped with inorganic materials. When this part of the water is dispersed into the concrete, it is equivalent to the dispersion of inorganic particles in the concrete system, so it has a more uniform dispersion. Subsequently, this part of the water in the inorganic capsule is gradually released and participates in the hydration reaction, which not only ensures the sufficient degree of the hydration reaction inside the entire concrete member, but also ensures the uniformity of hydration, thus making the mechanical strength of the member significantly higher overall.

[0047] It can be seen from the comparison between Example 2, Comparative Example 2 and Comparative Example 3 that when the water consumption in Comparative Example 3 is too small, it leads to incomplete hydration of the cement, which greatly affects the strength of the cement and concrete therein. At the same time, it also reflects from another side that: the water wrapped in the silicon-based inorganic capsule in this solution is indeed gradually released during the hydration process of the freshly mixed concrete and fully participates in the hydration reaction.

[0048] Meanwhile, as can be seen from Table 1, although a considerable portion of water is encapsulated with an inorganic wall in this solution, the fresh concrete still has an obvious slump and also meets the requirements of flowing concrete (slump between 100 mm and 150 mm), which is achieved by controlling the ratio between the natural water added to the concrete system and the water in the silicon-based water-containing capsules.

Claims

1. A fresh functional building concrete, characterized in that: The fresh concrete comprises, by weight, 100 parts of Portland cement clinker, 5 to 15 parts of fly ash, 2 to 10 parts of gypsum powder, 15 to 30 parts of silicon-based water-containing capsules, 30 to 40 parts of water, 180 to 230 parts of crushed stone, 80 to 100 parts of mixed sand, and 0.5 to 2 parts of a water reducing agent. The preparation method of the silicon-based water-containing capsule is as follows: dissolving a water-soluble alkali agent in pure water to obtain an alkaline aqueous solution, and then fully dispersing a quaternary ammonium salt cationic emulsifier in the alkaline aqueous solution as an aqueous phase; mixing and fully dispersing the aqueous phase and an oil phase based on a water-insoluble organic solvent in a mass ratio of 1:1 to 40 to obtain a mixed emulsion; after fully dispersing siloxane in the mixed emulsion for a hydrolysis reaction, separating the solid components generated by the reaction from the organic solvent to obtain the silicon-based water-containing capsule.

2. The freshly mixed concrete for functional buildings as described in claim 1, characterized in that: The weight ratio of the quaternary ammonium salt cationic emulsifier to the alkaline aqueous solution is 3 to 8:

100.

3. The fresh concrete for functional buildings as claimed in claim 1, wherein: The oil phase also includes a nonionic emulsifier, and the weight ratio of the nonionic emulsifier to the organic solvent is 0.01-0.5:

100.

4. The fresh concrete for functional buildings as claimed in claim 1, wherein: The weight ratio of the silicone to the mixed emulsion is 2-20:

100.

5. The freshly mixed concrete for functional buildings as claimed in claim 1, wherein: The hydrolysis reaction is carried out at 25°C to 70°C for 10 to 100 hours.

6. The fresh concrete for functional buildings according to claim 1, wherein: The composition of the silicate cement clinker includes 15 to 30 parts by weight of dicalcium silicate, 40 to 70 parts by weight of tricalcium silicate, 5 to 15 parts by weight of tricalcium aluminate, and 10 to 20 parts by weight of tetracalcium aluminoferrite.

7. The freshly mixed concrete for functional buildings as described in claim 1, characterized in that: The particle size of the crushed stone is between 5 and 20 mm.

8. The freshly mixed concrete for functional buildings as claimed in claim 7, wherein: The mixed sand includes fine sand with a particle size of 30 to 115 meshes and coarse sand with a particle size of 0.5 to 5 mm, and the weight ratio between the fine sand and the coarse sand is 1 to 1.5:

1.

9. A method for preparing precast components with the fresh functional building concrete according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: mixing the silicate cement clinker, the fly ash, the gypsum powder, the silicon-based water-containing capsule, the water, the crushed stone, the mixed sand and the water reducing agent, stirring the mixture at a speed of 60 to 120 revolutions per minute for 5 to 10 minutes, pouring the mixture into a mold, curing the mixture and then demoulding the mixture, thereby obtaining the prefabricated component.

10. The method for preparing precast members with the fresh functional building concrete according to claim 9, characterized in that: During the pouring process, the mold is shaken to tamp the mixture therein; after pouring, the top opening of the mold is smoothed to wipe off excess mixture; the mold filled with the mixture is then placed in a curing box at room temperature for 1.5 to 2 hours, the temperature in the curing box is steam heated to 50 to 60°C at a heating rate of 8 to 12°C / hour, and after heat preservation and curing for a period of time, when the temperature in the curing box naturally drops to below 45°C, it is cooled to room temperature at a cooling rate of 10 to 15°C / hour.

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