A special-shaped fair-faced concrete material and a preparation method thereof

Abstract

The application relates to the field of concrete, and particularly discloses a special-shaped fair-faced concrete material and a preparation method thereof. The fair-faced concrete material comprises the following raw materials in parts by weight: ordinary Portland cement 300-350 parts; grade II fly ash 35-50 parts; S95 grade mineral powder 60-80 parts; silica ash 30-32 parts; polycarboxylic acid water reducing agent 5.4-5.8 parts; HY type molecular sieve 10-12 parts; sodium gluconate 0.23-0.26 parts; river sand 700-800 parts; 5-25 mm continuous particle size gravel 1000-1100 parts; modified polyether defoaming agent 0.01-0.016 parts; and the rest is water, and the water-binder ratio is 0.38. The preparation method comprises the following steps: pretreating the raw materials; and mixing the raw materials. The fair-faced concrete material has excellent slump.

Description

Technical Field

[0001] This application relates to the field of concrete, and more specifically, to a shaped fair-faced concrete material and its preparation method. Background Technology

[0002] Fair-faced concrete is a type of concrete with a generally uniform surface color. It is formed by a combination of regularly arranged tie bolt holes, visible joints, chamfered joints, and artificial seams, resulting in a natural texture as its finish. Compared to ordinary concrete, it requires no external decoration after molding and possesses a natural aesthetic. The application of fair-faced concrete can reduce construction costs and enhance the visual appeal of buildings.

[0003] For some irregularly shaped fair-faced concrete structures, the unique architectural shapes, large fair-faced surface coverage, and high structural construction difficulty require fair-faced concrete with sufficient strength, durability, and self-cleaning properties to achieve the designer's goals of sharp angles, straight lines, and a natural and beautiful fair-faced concrete texture. However, currently common fair-faced concrete materials have poor slump, and after transportation, the strength of the constructed irregularly shaped fair-faced concrete cannot meet the usage requirements. Summary of the Invention

[0004] In order to maintain excellent slump in fair-faced concrete materials, this application provides an irregularly shaped fair-faced concrete material and its preparation method.

[0005] In a first aspect, this application provides an irregularly shaped fair-faced concrete material, which adopts the following technical solution:

[0006] A type of irregularly shaped fair-faced concrete material, comprising the following raw materials in parts by weight:

[0007] 300-350 parts of ordinary Portland cement;

[0008] 35-50 parts of Grade II fly ash;

[0009] 60-80 parts of S95 grade mineral powder;

[0010] 30-32 parts silica fume;

[0011] 5.4–5.8 parts of polycarboxylate superplasticizer;

[0012] 10-12 parts of HY type molecular sieve;

[0013] Sodium gluconate 0.23–0.26 parts;

[0014] 700-800 parts of medium sand from river sand;

[0015] 1000-1100 parts of 5-25mm continuous particle size crushed stone;

[0016] Modified polyether defoamer, 0.01–0.016 parts;

[0017] The remainder is water, with a water-to-glue ratio of 0.38.

[0018] By adopting the above technical solution, the cementitious material system includes ordinary Portland cement, ordinary Portland cement, Grade II fly ash, S95 grade mineral powder, and silica fume. Ordinary Portland cement serves as the basic cementitious material, hydrating to generate CSH gel and Ca(OH)2, providing a strength skeleton. Grade II fly ash, consisting of micron-sized particles, fills the voids in S95 mineral powder. Its spherical particle shape acts as a "ball lubricant" in the slurry, improving its fluidity, reducing air bubble adhesion, and reacting with Ca(OH)2 to generate secondary CSH, enhancing the later-stage strength and durability of the concrete. S95 grade mineral powder, as fine particles, fills cement pores, exhibiting higher activity than fly ash and creating a "synergistic effect" with it. Silica fume, consisting of submicron-sized particles, fills even finer pores between cement particles and fly ash / mineral powder, significantly increasing the density of the concrete. It also reacts rapidly with Ca(OH)2 to generate additional CSH gel. This close-packing theory greatly improves the matrix density, forming the basis for the smooth surface finish of fair-faced concrete.

[0019] The slump control system includes polycarboxylate superplasticizer, HY-type molecular sieve, and sodium gluconate. The comb-like main chain of the polycarboxylate superplasticizer adsorbs cement particles, while the side chains provide steric hindrance, achieving efficient dispersion and reducing the water-cement ratio. The HY-type molecular sieve has a regular crystal structure, which can serve as nucleation sites for CSH gel, refining the grain size. It can also rapidly adsorb Ca from the cement paste through ion exchange. 2+ It delays C3S hydration and ettringite formation, achieving ultimate slump retention; the hydroxyl and carboxyl groups of sodium gluconate adsorb onto the surface of cement particles, chelating liquid-phase Ca... 2+ Together with HY-type molecular sieves, they can delay hydration through different pathways, forming a dual retarding mechanism of "chemical chelation + physical adsorption". The combined effect of the three can effectively maintain the excellent slump of concrete materials, thereby improving the strength of concrete structures.

[0020] The cementitious material system is rich in powdered fillers. To maintain excellent surface quality, a modified polyether defoamer is added in combination with a polycarboxylate superplasticizer. This defoamer exhibits stable performance within the polycarboxylate superplasticizer system, exhibiting no stratification or sedimentation during long-term storage. It precisely controls the air content of the concrete, eliminating harmful large air bubbles while retaining beneficial small air bubbles. The defoamer causes large air bubbles to burst and float to the surface, while the morphological effect of fly ash improves the rheological properties of the paste. Together, they ensure the complete removal of air bubbles. The aggregate consists of river sand, medium sand, and 5-25mm continuous-sized crushed stone, with a sand ratio maintained at approximately 41%. The aggregate has a moderate specific surface area, sufficient free paste layer thickness, and dense filling of irregular corners. After the defoamer eliminates large air bubbles, the ample free paste can evenly coat the aggregate, resulting in a smooth concrete surface.

[0021] Therefore, it achieves the effect of maintaining excellent slump in fair-faced concrete materials.

[0022] Optionally, the HY-type molecular sieve has a silica-to-alumina ratio of 4 to 6 and a particle size of 0.5 to 2 μm.

[0023] By employing the above technical solutions, if the molecular sieve particle size is too large, it will not be able to achieve the micro-filling effect; if the silicon-to-aluminum ratio is too low, the acidity may be too strong, which may affect coagulation. The HY type molecular sieve of this specification has the best effect.

[0024] Optionally, the particle size of the silica fume is 0.1 to 0.3 μm.

[0025] By adopting the above technical solution, this specification of silica fume achieves the best results.

[0026] Optionally, the fair-faced concrete material further includes 2.2 to 2.8 parts by weight of modified sisal fiber and 50 to 70 parts by weight of PAE emulsion.

[0027] By adopting the above technical solution, modified sisal fiber and PAE emulsion constitute a toughening and crack-resistant system. Modified sisal fiber can form a three-dimensional network in concrete, bridging microcracks, preventing crack propagation, and changing the failure mode from brittle to plastic failure. Furthermore, after absorbing water in the early stages, modified sisal fiber can release water in the later stages of cement hydration, promoting hydration, reducing autogenous shrinkage, and providing internal curing. As hydration progresses, PAE emulsion not only provides toughness, but its cationic properties also interact with negatively charged cement particles, improving the interfacial transition zone. The resulting continuous three-dimensional network film can encapsulate cement hydrates and aggregates, increasing the strength of the concrete. PAE emulsion also provides some protection for the modified sisal fiber. Modified sisal fiber provides rigid bridging and crack prevention, while PAE emulsion film formation provides flexible toughening; together, they form a dual toughening mechanism of "rigidity and flexibility," enhancing the strength of the concrete structure.

[0028] In addition, the pozzolanic reaction of silica fume can optimize the fiber-matrix interface transition zone and improve the bonding strength between modified sisal fibers and the matrix.

[0029] In terms of slump control, sodium gluconate provides rapid initial slow coagulation, while the ester groups of the PAE emulsion undergo slow-release hydrolysis in the later stages. The two complement each other in time, ensuring that the slump control effect covers the entire transportation process. The micropores of the HY-type molecular sieve may also adsorb a small amount of PAE emulsion molecules, regulating their slow-release rate. The combined use of these three components further enhances the slump control effect.

[0030] Optionally, the modified sisal fiber is sisal fiber modified by soaking in a 5% NaOH solution.

[0031] By adopting the above technical solution, untreated sisal fibers will degrade and become ineffective within a few weeks in an environment with pH > 12. Alkaline treatment can remove impurities and waxes from the surface of sisal fibers, expose cellulose hydroxyl groups, significantly improve the chemical bonding force and mechanical interlocking force with the cement matrix, and enhance the bonding strength between sisal fibers and the matrix.

[0032] Optionally, the length of the modified sisal fiber is 8–15 mm.

[0033] By adopting the above technical solution, 8-15mm is suitable for suppressing plastic shrinkage cracks and early micro-cracks in concrete, and will not seriously affect the filling fluidity of irregular component molds.

[0034] Secondly, this application provides a method for preparing irregularly shaped fair-faced concrete material, employing the following technical solution:

[0035] A method for preparing an irregularly shaped fair-faced concrete material includes the following steps:

[0036] (1) Raw material pretreatment: Add some water to the HY type molecular sieve for pre-wetting, let it stand until it reaches a saturated water absorption state; dissolve sodium gluconate in some water and disperse it evenly; premix the modified polyether defoamer and polycarboxylate superplasticizer evenly;

[0037] (2) Mixing of raw materials: First, add pre-wetted HY molecular sieve, silica fume, ordinary silicate cement, grade II fly ash, and grade S95 mineral powder, and stir evenly; then add river sand, medium sand, and 5-25mm continuous particle size crushed stone, and stir evenly; then add pre-dissolved sodium gluconate and the remaining water, and stir evenly; finally, add the premixed liquid of modified polyether defoamer and polycarboxylate superplasticizer, stir evenly, and discharge.

[0038] By adopting the above technical solution, the HY type molecular sieve is pre-wetted with some water. After pre-absorbing water, it can avoid competing for free water in the concrete material in the early stage of mixing, thereby maintaining the fluidity of the slurry. The defoamer is easy to float and fail when added directly to water. Premixing it with the water-reducing agent can take advantage of the dispersibility of the water-reducing agent to uniformly carry it into the system.

[0039] Thirdly, this application provides a method for preparing irregularly shaped fair-faced concrete material, employing the following technical solution:

[0040] A method for preparing an irregularly shaped fair-faced concrete material includes the following steps:

[0041] (1) Raw material pretreatment: Add some water to the HY type molecular sieve for pre-wetting, let it stand until it reaches a saturated water absorption state; dissolve sodium gluconate in some water and disperse it evenly; premix the modified polyether defoamer and polycarboxylate superplasticizer evenly; prepare modified sisal fiber, immerse the modified sisal fiber in PAE emulsion and take it out, dry it to constant weight, and coat its surface with a film;

[0042] (2) Mixing of raw materials: First, add pre-wetted HY molecular sieve, silica fume, ordinary silicate cement, grade II fly ash, and grade S95 mineral powder, and stir evenly; then add modified sisal fiber, stir evenly to disperse the modified sisal fiber evenly; then add river sand, medium sand, and 5-25mm continuous particle size crushed stone, and stir evenly; then add water accounting for 80% of the total water weight, containing pre-dissolved sodium gluconate, and stir evenly; then slowly add PAE emulsion and the remaining water after mixing and diluting; finally add the premixed liquid of modified polyether defoamer and polycarboxylate superplasticizer, stir evenly, and discharge.

[0043] By adopting the above technical solution, during the mixing process, the modified sisal fiber is first soaked in the PAE emulsion, which can provide a certain degree of protection for it; dry mixing first allows the modified sisal fiber to be initially dispersed in the powder, avoiding clumping during wet mixing; the PAE emulsion is added slowly after dilution, which can prevent high concentrations of emulsion from damaging cement hydration or causing segregation.

[0044] In summary, this application has the following beneficial effects:

[0045] 1. Because this application uses polycarboxylate superplasticizer, HY-type molecular sieve, and sodium gluconate as the slump control system, the comb-shaped main chain of the polycarboxylate superplasticizer adsorbs cement particles, while the side chains provide steric hindrance, achieving efficient dispersion and reducing the water-cement ratio; the HY-type molecular sieve has a regular crystal structure, which can serve as nucleation sites for CSH gel, refining the grains, and can also rapidly adsorb Ca in the cement paste through ion exchange. 2+ It delays C3S hydration and ettringite formation, achieving ultimate slump retention; the hydroxyl and carboxyl groups of sodium gluconate adsorb onto the surface of cement particles, chelating liquid-phase Ca...2+ Together with HY-type molecular sieves, they can delay hydration through different pathways, forming a dual retarding mechanism of "chemical chelation + physical adsorption". The combined effect of the three can effectively maintain the excellent slump of concrete materials, thereby improving the strength of concrete structures.

[0046] 2. In this application, modified sisal fiber and PAE emulsion are preferred to form a toughening and crack-resistant system. Modified sisal fiber provides rigid bridging and crack resistance, while PAE emulsion film formation provides flexible toughening. The two form a dual toughening mechanism of "rigidity and flexibility", which improves the strength of concrete structure.

[0047] 3. The method of this application uses HY-type molecular sieve to add some water for pre-wetting. After pre-absorbing water, it can avoid competing for free water in the concrete material in the early stage of mixing, thereby maintaining the fluidity of the slurry. The defoamer is easy to float and fail when added directly to water. Premixing it with the water-reducing agent can take advantage of the dispersibility of the water-reducing agent to uniformly carry it into the system, thus achieving the effect of improving the slump retention and strengthening of the concrete material. Detailed Implementation

[0048] The present application will be further described in detail below with reference to the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments shall be performed under conventional conditions or conditions recommended by the manufacturer, and the raw materials used in the following embodiments shall be commercially available unless otherwise specified.

[0049] Ordinary silicate cement, Conch brand, PO 42.5.

[0050] Grade II fly ash, with a loss on ignition of less than 5%.

[0051] S95 grade mineral powder, specific surface area 400m² 2 / kg.

[0052] Silica ash, brand Yitian.

[0053] Polycarboxylate superplasticizer, Subote PCA-I.

[0054] HY type molecular sieve, brand Zhuoran Environmental Protection.

[0055] The river sand is medium sand with a fineness modulus of 2.8.

[0056] Modified polyether defoamer, brand name: Zhonglianbang, name: polycarboxylate defoamer, model: B-349.

[0057] PAE emulsion, brand Shandong Zhuorui Chemical, solid content 15.63%.

[0058] Sisal fiber, a pre-processed fiber filament that has undergone degumming treatment.

[0059] Water, tap water.

[0060] Preparation example of modified sisal fiber

[0061] Preparation Example 1

[0062] The method for preparing modified sisal fiber is as follows: cut the sisal fiber to 8 mm, then immerse it completely in a 5% NaOH solution for 30 min, with a fiber to solution weight ratio of 1:30, ensuring that the fiber is completely submerged and can be freely turned over, then wash it with water until neutral, and dry it to constant weight to obtain modified sisal fiber.

[0063] Preparation Example 2

[0064] The modified sisal fiber is prepared by cutting the sisal fiber to 12 mm and then immersing it completely in a 5% NaOH solution for 30 min. The fiber to solution weight ratio is 1:30. Ensure that the fiber is completely submerged and can be freely turned over. Then wash it with water until neutral and dry it to constant weight to obtain the modified sisal fiber.

[0065] Preparation Example 3

[0066] The modified sisal fiber is prepared by cutting the sisal fiber to 15 mm and then immersing it completely in a 5% NaOH solution for 30 min. The fiber to solution weight ratio is 1:30, ensuring that the fiber is completely submerged and can be freely turned over. Then, it is washed with water until neutral and dried to constant weight to obtain the modified sisal fiber.

[0067] Example

[0068] Example 1

[0069] A type of irregularly shaped fair-faced concrete material, comprising the following raw materials:

[0070] Ordinary silicate cement; Grade II fly ash; S95 grade mineral powder; silica fume, particle size 0.1μm; polycarboxylate superplasticizer; HY type molecular sieve, silica-alumina ratio 4, particle size 0.5μm; sodium gluconate; medium river sand; 5-25mm continuous particle size crushed stone; modified polyether defoamer; the remainder is water, water-binder ratio 0.38. See Table 1 for the dosage of each raw material.

[0071] A method for preparing an irregularly shaped fair-faced concrete material includes the following steps:

[0072] (1) Raw material pretreatment: Add some water to the HY type molecular sieve for pre-wetting, let it stand for 10 minutes to reach the state of saturated water absorption; dissolve sodium gluconate in some water to disperse it evenly; premix the modified polyether defoamer and polycarboxylate water-reducing agent evenly.

[0073] (2) Mixing of raw materials: First, add pre-wetted HY molecular sieve, silica fume, ordinary silicate cement, grade II fly ash, and grade S95 mineral powder, and stir evenly; then add river sand, medium sand, and 5-25mm continuous particle size crushed stone, and stir evenly; then add pre-dissolved sodium gluconate and the remaining water, and stir evenly; finally, add the premixed liquid of modified polyether defoamer and polycarboxylate superplasticizer, stir evenly, and discharge.

[0074] Example 2

[0075] A type of irregularly shaped fair-faced concrete material, comprising the following raw materials:

[0076] Ordinary silicate cement; Grade II fly ash; S95 grade mineral powder; silica fume, particle size 0.2μm; polycarboxylate superplasticizer; HY type molecular sieve, silica-alumina ratio 5, particle size 1μm; sodium gluconate; medium river sand; 5-25mm continuous particle size crushed stone; modified polyether defoamer; the remainder is water, water-binder ratio 0.38. See Table 1 for the dosage of each raw material.

[0077] A method for preparing an irregularly shaped fair-faced concrete material is the same as in Example 1.

[0078] Example 3

[0079] A type of irregularly shaped fair-faced concrete material, comprising the following raw materials:

[0080] Ordinary silicate cement; Grade II fly ash; S95 grade mineral powder; silica fume, particle size 0.3μm; polycarboxylate superplasticizer; HY type molecular sieve, silica-alumina ratio 6, particle size 2μm; sodium gluconate; medium river sand; 5-25mm continuous particle size crushed stone; modified polyether defoamer; the remainder is water, water-binder ratio 0.38. See Table 1 for the dosage of each raw material.

[0081] A method for preparing an irregularly shaped fair-faced concrete material is the same as in Example 1.

[0082] Example 4

[0083] The difference between this embodiment and Embodiment 2 is that the silicon-to-aluminum ratio of the HY-type molecular sieve in this embodiment is 2.

[0084] Example 5

[0085] The difference between this embodiment and Embodiment 2 is that the particle size of the HY-type molecular sieve in this embodiment is 12 μm.

[0086] Example 6

[0087] The difference between this embodiment and Embodiment 2 is that the irregular-shaped decorative fair-faced concrete material further includes modified sisal fiber and PAE emulsion. The modified sisal fiber is prepared according to the method of Preparation Example 1. The amounts of each raw material are detailed in Table 1.

[0088] A method for preparing an irregularly shaped fair-faced concrete material, characterized by comprising the following steps:

[0089] (1) Raw material pretreatment: Add some water to the HY type molecular sieve for pre-wetting, let it stand for 10 minutes to reach a saturated water absorption state; dissolve sodium gluconate in some water to disperse it evenly; premix the modified polyether defoamer and polycarboxylate superplasticizer evenly; prepare modified sisal fiber according to the method of Preparation Example 1, immerse the modified sisal fiber in PAE emulsion for 10 minutes and take it out, dry it to constant weight, and coat its surface with a film.

[0090] (2) Mixing of raw materials: First, add pre-wetted HY molecular sieve, silica fume, ordinary silicate cement, grade II fly ash, and grade S95 mineral powder, and stir evenly; then add modified sisal fiber, stir evenly to disperse the modified sisal fiber evenly; then add river sand, medium sand, and 5-25mm continuous particle size crushed stone, and stir evenly; then add water accounting for 80% of the total water weight, containing pre-dissolved sodium gluconate, and stir evenly; then slowly add PAE emulsion and the remaining water after mixing and diluting; finally add the premixed liquid of modified polyether defoamer and polycarboxylate superplasticizer, stir evenly, and discharge.

[0091] Example 7

[0092] The difference between this embodiment and Example 6 is that the modified sisal fiber is prepared according to the method of Preparation Example 2, and the amounts of modified sisal fiber and PAE emulsion are different, as detailed in Table 1.

[0093] Example 8

[0094] The difference between this embodiment and Example 6 is that the modified sisal fiber is prepared according to the method of Preparation Example 3, and the amounts of modified sisal fiber and PAE emulsion are different, as detailed in Table 1.

[0095] Example 9

[0096] The difference between this embodiment and Embodiment 7 is that unmodified sisal fiber is used to replace the modified sisal fiber in the raw materials, and the sisal fiber is not included in the PAE emulsion after coating.

[0097] Example 10

[0098] The difference between this embodiment and Embodiment 7 is that PAE emulsion was not added in this embodiment.

[0099] Example 11

[0100] The difference between this embodiment and Embodiment 7 is that all raw materials are added together and mixed evenly.

[0101] Comparative Example

[0102] Comparative Example 1

[0103] The difference between this comparative example and Example 2 is that HY-type molecular sieve, sodium gluconate, silica fume, and modified polyether defoamer were not added in this comparative example.

[0104] Comparative Example 2

[0105] The difference between this comparative example and Example 2 is that HY-type molecular sieve and sodium gluconate were not added in this comparative example.

[0106] Comparative Example 3

[0107] The difference between this comparative example and Example 2 is that HY-type molecular sieve was not added in this comparative example.

[0108] Comparative Example 4

[0109] The difference between this comparative example and Example 2 is that sodium gluconate was not added in this comparative example.

[0110] Comparative Example 5

[0111] The difference between this comparative example and Example 2 is that no silica fume was added in this comparative example.

[0112] Comparative Example 6

[0113] The difference between this comparative example and Example 2 is that no modified polyether defoamer was added in this comparative example.

[0114] Comparative Example 7

[0115] The difference between this comparative example and Example 2 is that the HY type molecular sieve in this comparative example was not pre-wetted.

[0116] Table 1. Amounts of each raw material except water in each embodiment and comparative example (unit: kg / m³) 3 )

[0117] Ordinary Portland cement Class II fly ash S95 grade mineral powder silica ash Polycarboxylate superplasticizer HY type molecular sieve Sodium gluconate River sand medium sand gravel Modified polyether defoamers Modified sisal fiber PAE emulsion Example 1 300 35 60 30 5.4 10 0.23 700 1000 0.01 0 0 Example 2 320 40 70 31.5 5.5 10.5 0.25 760 1060 0.013 0 0 Example 3 350 50 80 32 5.8 12 0.26 800 1100 0.016 0 0 Example 4 320 40 70 31.5 5.5 10.5 0.25 760 1060 0.013 0 0 Example 5 320 40 70 31.5 5.5 10.5 0.25 760 1060 0.013 0 0 Example 6 320 40 70 31.5 5.5 10.5 0.25 760 1060 0.013 2.2 50 Example 7 320 40 70 31.5 5.5 10.5 0.25 760 1060 0.013 2.5 64 Example 8 320 40 70 31.5 5.5 10.5 0.25 760 1060 0.013 2.8 70 Example 9 320 40 70 31.5 5.5 10.5 0.25 760 1060 0.013 Unmodified 64 Example 10 320 40 70 31.5 5.5 10.5 0.25 760 1060 0.013 2.5 0 Example 11 320 40 70 31.5 5.5 10.5 0.25 760 1060 0.013 2.5 64 Comparative Example 1 320 40 70 0 5.5 0 0 760 1060 0 0 0 Comparative Example 2 320 40 70 31.5 5.5 0 0 760 1060 0.013 0 0 Comparative Example 3 320 40 70 31.5 5.5 0 0.25 760 1060 0.013 0 0 Comparative Example 4 320 40 70 31.5 5.5 10.5 0 760 1060 0.013 0 0 Comparative Example 5 320 40 70 0 5.5 10.5 0.25 760 1060 0.013 0 0 Comparative Example 6 320 40 70 31.5 5.5 10.5 0.25 760 1060 0 0 0 Comparative Example 7 320 40 70 31.5 5.5 10.5 0.25 760 1060 0.013 0 0

[0118] Performance testing

[0119] Detection methods

[0120] 1. Slump: The fair-faced concrete materials prepared in the above examples and comparative examples were sampled and tested in accordance with Section 4 "Slump Test and Slump Loss Over Time Test" of "GB / T 50080-2016 Standard for Test Methods of Performance of Ordinary Concrete Mixtures". The test results are detailed in Table 2.

[0121] 2. Spreadability: The fair-faced concrete materials prepared in the above embodiments and comparative examples were sampled and tested in accordance with Section 5 "Spreadability Test and Spreadability Loss Over Time Test" of "GB / T 50080-2016 Standard for Test Methods of Performance of Ordinary Concrete Mixtures". The test results are detailed in Table 2.

[0122] 3. Air content: The fair-faced concrete materials prepared in the above examples and comparative examples were sampled and tested in accordance with Section 15 "Air content test" of "GB / T 50080-2016 Standard for Test Methods of Performance of Ordinary Concrete Mixtures". The test results are detailed in Table 2.

[0123] 4. Following the guidelines in Section 4 of "GB / T 50081-2019 Standard for Test Methods of Physical and Mechanical Properties of Concrete", specimens of the fair-faced concrete materials prepared in the above embodiments and comparative examples were prepared and cured using an immersion vibrator. The curing period was 28 days, and the following tests were conducted:

[0124] Compressive strength: The specimens were tested according to the method in Section 5 "Compressive Strength Test" of "GB / T 50081-2019 Standard for Test Methods of Physical and Mechanical Properties of Concrete". The test results are detailed in Table 2.

[0125] Flexural strength: The specimens were tested according to the method of Section 10 "Flexural Strength Test" in "GB / T 50081-2019 Standard for Test Methods of Physical and Mechanical Properties of Concrete". The test results are detailed in Table 2.

[0126] Early crack resistance: The specimens were tested according to the method of Section 9 "Early crack resistance test" in "GB / T 50082-2024 Standard for Test Methods of Long-term Performance and Durability of Concrete". The test results are detailed in Table 2.

[0127] Surface quality: The specimens were tested according to Appendix G, Test method for air bubble spacing coefficient of hardened concrete, in “TB / T 3275-2018 Railway Concrete”. The test results are detailed in Table 2.

[0128] Table 2 Test Results

[0129] Initial slump / mm 2h slump / mm 2h loss rate / % Initial expansion / mm Gas content / % Pressure resistance / MPa Flexural strength / MPa Initial cracking time / h Crack area (mm² / m²) Maximum crack width / mm Surface bubble density (bubbles / m²) Maximum bubble diameter / mm Example 1 190 145 23.7 480 2.6 57.5 7.2 5.5 180 0.25 28 4.2 Example 2 210 180 14.3 550 2.3 63 7.5 7 70 0.1 14 2.3 Example 3 200 160 20 520 2.2 63.5 7.6 7.2 65 0.09 12 2 Example 4 200 145 27.5 520 2.5 61 7.4 6 140 0.2 20 3.3 Example 5 180 115 36.1 460 2.5 57.5 7.1 4.8 260 0.35 28 4 Example 6 200 160 20 510 2.4 61 8.7 8.5 30 0.04 18 2.8 Example 7 195 155 20.5 500 2.5 60.5 9.2 9.5 18 0.03 20 3 Example 8 180 125 30.6 470 2.6 58.5 8.8 8.8 25 0.04 24 3.6 Example 9 175 110 37.1 450 3 54.5 7.6 6.5 120 0.18 36 5.2 Example 10 205 120 41.5 530 2.6 62 7.9 7.5 55 0.08 18 2.8 Example 11 150 80 46.7 380 3.5 49.5 6.8 4 320 0.45 65 8.5 Comparative Example 1 160 75 53.1 400 4 47 5.8 3 550 0.7 120 13 Comparative Example 2 185 105 43.2 470 3.2 58 7 4.2 300 0.42 60 7.5 Comparative Example 3 190 110 42.1 480 3 58.5 7.1 4.5 280 0.4 55 7 Comparative Example 4 195 120 38.5 490 2.8 59 7.2 4.8 240 0.35 50 6.5 Comparative Example 5 170 100 41.2 430 2.9 50 6.4 4 350 0.48 48 5.8 Comparative Example 6 220 170 22.7 580 5.5 53.5 6.7 5.5 200 0.28 180 17 Comparative Example 7 130 60 53.8 320 3.8 48 6 3.5 450 0.6 90 9.5

[0130] As can be seen from Example 2 and Comparative Example 1, and Table 2, the fair-faced concrete material formula of this application has a high degree of compatibility among the various systems, can maintain excellent slump, and the resulting concrete structure also has high strength.

[0131] Combining Example 2 and Comparative Examples 1 to 6 with Table 2, it can be seen that the overall performance of the material is optimal only under the combined effect of each system. In particular, the experimental results corresponding to Example 2, Comparative Examples 2, 3, and 4 show that the slump-retention and regulation system formed by HY molecular sieve and sodium gluconate in combination with polycarboxylate superplasticizer has a synergistic effect among the raw materials, contributing a very large slump-retention effect.

[0132] As can be seen from Example 2 and Comparative Example 7, and in conjunction with Table 2, the concrete material preparation method of this application also has good advantages.

[0133] As can be seen from Examples 2 and 7, and Table 2, the addition of modified sisal fiber and PAE emulsion significantly improved the flexural and crack strength of the concrete structure while maintaining excellent slump retention. The synergistic toughening effect of the two is also evident in Examples 9 and 10.

[0134] As can be seen from Examples 7 and 11 and Table 2, stepwise feeding has obvious effects on slump retention and reinforcement.

[0135] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A type of irregularly shaped fair-faced concrete material, characterized in that, Including the following parts by weight of raw materials: 300-350 parts of ordinary Portland cement; 35-50 parts of Grade II fly ash; 60-80 parts of S95 grade mineral powder; 30-32 parts silica fume; 5.4–5.8 parts of polycarboxylate superplasticizer; 10-12 parts of HY type molecular sieve; Sodium gluconate 0.23–0.26 parts; 700-800 parts of medium sand from river sand; 1000-1100 parts of 5-25mm continuous particle size crushed stone; Modified polyether defoamer, 0.01–0.016 parts; The remainder is water, with a water-to-glue ratio of 0.

38.

2. The irregular-shaped fair-faced concrete material according to claim 1, characterized in that: The HY-type molecular sieve has a silicon-to-aluminum ratio of 4 to 6 and a particle size of 0.5 to 2 μm.

3. The irregular-shaped fair-faced concrete material according to claim 1, characterized in that: The particle size of the silica fume is 0.1–0.3 μm.

4. The irregular-shaped fair-faced concrete material according to claim 1, characterized in that: The fair-faced concrete material also includes 2.2 to 2.8 parts by weight of modified sisal fiber and 50 to 70 parts by weight of PAE emulsion.

5. The irregular-shaped fair-faced concrete material according to claim 4, characterized in that: The modified sisal fiber is sisal fiber modified by soaking in a 5% NaOH solution.

6. The irregular-shaped fair-faced concrete material according to claim 5, characterized in that: The length of the modified sisal fiber is 8–15 mm.

7. A method for preparing an irregularly shaped fair-faced concrete material according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Raw material pretreatment: Add some water to the HY type molecular sieve for pre-wetting, let it stand until it reaches a saturated water absorption state; dissolve sodium gluconate in some water and disperse it evenly; premix the modified polyether defoamer and polycarboxylate superplasticizer evenly; (2) Mixing of raw materials: First, add pre-wetted HY molecular sieve, silica fume, ordinary silicate cement, grade II fly ash, and grade S95 mineral powder, and stir evenly; then add river sand, medium sand, and 5-25mm continuous particle size crushed stone, and stir evenly; then add pre-dissolved sodium gluconate and the remaining water, and stir evenly; finally, add the premixed liquid of modified polyether defoamer and polycarboxylate superplasticizer, stir evenly, and discharge.

8. A method for preparing an irregularly shaped fair-faced concrete material according to any one of claims 4 to 6, characterized in that, Includes the following steps: (1) Raw material pretreatment: Add some water to the HY type molecular sieve for pre-wetting, let it stand until it reaches a saturated water absorption state; dissolve sodium gluconate in some water and disperse it evenly; premix the modified polyether defoamer and polycarboxylate superplasticizer evenly; prepare modified sisal fiber, immerse the modified sisal fiber in PAE emulsion and take it out, dry it to constant weight, and coat its surface with a film; (2) Mixing of raw materials: First, add pre-wetted HY molecular sieve, silica fume, ordinary silicate cement, grade II fly ash, and grade S95 mineral powder, and stir evenly; then add modified sisal fiber, stir evenly to disperse the modified sisal fiber evenly; then add river sand, medium sand, and 5-25mm continuous particle size crushed stone, and stir evenly; then add water accounting for 80% of the total water weight, containing pre-dissolved sodium gluconate, and stir evenly; then slowly add PAE emulsion and the remaining water after mixing and diluting; finally add the premixed liquid of modified polyether defoamer and polycarboxylate superplasticizer, stir evenly, and discharge.