High-performance cement concrete and preparation method thereof

Abstract

The present invention belongs to the field of building materials technology and relates to a high-performance cement concrete and its preparation method. The raw materials include cement, ultrafine admixtures, quartz sand, aggregate, a fiber composition, a water reducer, a silane emulsion, and water. This invention improves the density of the cement concrete through a gradient compounding of quartz sand and aggregate. The mechanical properties of the cement concrete are enhanced by combining the fly ash and silica fume in the ultrafine admixtures with the steel fibers and polyvinyl alcohol fibers in the fiber composition, thus resolving the significant decrease in mechanical properties caused by the addition of silane emulsion.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and more particularly relates to a high-performance cement concrete and a preparation method thereof. Background Art

[0002] Concrete refers to an artificial stone material made by uniformly mixing cement as the primary gelling material with water, sand, gravel, chemical additives, and admixtures, forming, and hardening it. Water transport through porous materials primarily occurs through pressure-driven diffusion, concentration-driven osmosis, and capillary absorption. Furthermore, carbon dioxide and harmful ions such as chloride and sulfate from the surrounding environment can enter the concrete through the migration of water through the pores, thereby affecting the durability of the entire concrete structure, resulting in low corrosion resistance and a shortened service life.

[0003] In the existing technology, on the one hand, the purpose of protecting concrete is achieved by coating a hydrophobic layer on the concrete surface. However, when the hydrophobic layer often faces problems such as aging and cracking or failure after the surface is damaged and peeled off, it still cannot substantially solve the corrosion of concrete by moisture and harmful ions. On the other hand, hydrophobic agents are added to concrete by internal mixing, but this internal mixing method often causes a significant reduction in the mechanical properties of concrete.

[0004] As urban areas expand, a large number of buildings need to be constructed. As the most widely used building material in modern times, concrete requires large quantities of preparation and use. Furthermore, it is necessary to ensure that the concrete can be properly constructed and has sufficient strength after molding. Therefore, how to improve the corrosion resistance of concrete without affecting its mechanical properties is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-performance cement concrete and a preparation method thereof, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide a high-performance cement concrete comprising the following components in parts by mass:

[0008] 600-700 parts of cement, 150-250 parts of ultrafine admixture, 1000-1300 parts of quartz sand, 300-600 parts of aggregate, 100-120 parts of fiber composition, 8-10 parts of water reducer, 10-40 parts of silane emulsion and 150-200 parts of water.

[0009] Furthermore, the cement is silicate cement with a brand name of PO42.5.

[0010] Furthermore, the ultrafine admixture consists of fly ash and silica fume in a mass ratio of 1:1.25.

[0011] Furthermore, the quartz sand is a mixture of coarse sand, medium sand and fine sand, with a mass ratio of 1:0.4-0.5:0.2-0.3.

[0012] Preferably, the particle size of the coarse sand is 0.5-0.8 mm; the particle size of the medium sand is 0.3-0.5 mm; and the particle size of the fine sand is 0.2-0.3 mm.

[0013] Furthermore, the aggregate is a mixture of coarse aggregate and fine aggregate in a mass ratio of 3-5:1-2.

[0014] Preferably, the particle size of the coarse aggregate is 10-15 mm, and the particle size of the fine aggregate is 3-5 mm.

[0015] Furthermore, the fiber composition is a mixture of steel fiber and polyvinyl alcohol fiber, with a mass ratio of 1:0.4 to 0.6.

[0016] Preferably, the steel fiber is a corrugated steel fiber or a hook-shaped steel fiber.

[0017] Furthermore, the water reducer is a polycarboxylic acid water reducer.

[0018] Furthermore, the silane emulsion includes one of isobutylene triethoxysilane emulsion, n-octyl triethoxysilane emulsion and isooctyl triethoxysilane emulsion, and the content of active ingredients is not less than 45%.

[0019] The second technical solution of the present invention is to provide a method for preparing the above-mentioned high-performance cement concrete, comprising:

[0020] Evenly mixing the silane emulsion, the water reducing agent and water to obtain mixing water;

[0021] Put cement, ultrafine admixture, quartz sand, aggregate and fiber composition into a mixer and stir for 5 to 10 minutes to obtain a dry mix;

[0022] The dry mix is ​​evenly added with the mixing water while stirring, and the stirring is continued for more than 10 minutes to obtain the high-performance cement concrete.

[0023] The third technical solution of the present invention is to provide an application of the above-mentioned high-performance cement concrete in construction projects.

[0024] It can be seen from the above technical solution that compared with the existing technology, it has the following beneficial effects:

[0025] In the present invention, emulsion particles added with silane emulsion are deposited in large quantities on the surface of cement particles, forming cement particles coated with emulsion particles. After curing, the presence of the coating layer improves the hydrophobicity of the capillary pores on the concrete surface, thereby achieving the effect of resisting water erosion. At the same time, the hydrophobicity effectively reduces the damage to the concrete caused by harmful ions entering the interior of the concrete through the migration of water in the capillary pores.

[0026] Since the addition of silane emulsion will lead to a decrease in the strength of concrete, the present invention increases the density of concrete through the gradient grading of quartz sand and the gradient grading of aggregate, thereby improving the strength of concrete after curing. At the same time, the ultrafine admixture in the present invention uses a composite of fly ash and silica fume, which can fill the pores between the particles of each component, reduce the water consumption and cement usage of the castable, and cooperate with quartz sand and aggregate to make the concrete denser, thereby improving the wear resistance and cavitation resistance of the concrete.

[0027] The polyvinyl alcohol fibers in the present invention have a bridging effect and can control micro cracks, and the steel fibers can inhibit the expansion of macro cracks. The composite use of the polyvinyl alcohol fibers and the steel fibers significantly improves the compressive strength and flexural strength of concrete.

[0028] The present invention limits the water-binder ratio and the sand-binder ratio by limiting the mass parts of each component. Cement concrete with excellent mechanical properties and strong corrosion resistance can be obtained by mixing within the mass parts defined in the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] In the embodiment of the present invention:

[0031] The particle size of coarse sand is between 0.5 and 0.8 mm; the particle size of medium sand is between 0.3 and 0.5 mm; and the particle size of fine sand is between 0.2 and 0.3 mm.

[0032] The particle size of the coarse aggregate is crushed stone between 10 and 15 mm, and the particle size of the fine aggregate is crushed stone between 3 and 5 mm.

[0033] The cement is silicate cement with the brand name PO42.5.

[0034] The active ingredient content of the silane emulsion is 50%.

[0035] Example 1

[0036] Preparation of high performance cement concrete:

[0037] Mix 20 parts of isobutylene triethoxysilane emulsion, 9 parts of polycarboxylic acid water reducer and 170 parts of water to obtain mixing water;

[0038] 660 parts of cement, 230 parts of ultrafine admixture, 1200 parts of quartz sand, 400 parts of aggregate and 116 parts of fiber composition were put into a mixer and stirred for 8 minutes to obtain a dry mix;

[0039] The high-performance cement concrete is obtained by uniformly adding mixing water to the dry mix while stirring and continuing to stir for 10 minutes.

[0040] The mass ratio of fly ash to silica fume in the ultrafine admixture is 1:1.25.

[0041] The mass ratio of coarse sand, medium sand and fine sand in quartz sand is 1:0.45:0.27.

[0042] The mass ratio of coarse aggregate to fine aggregate in the aggregate is 4:1.5.

[0043] The mass ratio of the corrugated steel fiber to the polyvinyl alcohol fiber in the fiber composition is 1:0.45.

[0044] Example 2

[0045] Preparation of high performance cement concrete:

[0046] Mix 10 parts of n-octyltriethoxysilane emulsion, 8 parts of polycarboxylic acid water reducer and 150 parts of water to obtain mixing water;

[0047] 600 parts of cement, 150 parts of ultrafine admixture, 1000 parts of quartz sand, 300 parts of aggregate and 100 parts of fiber composition were put into a mixer and stirred for 10 minutes to obtain a dry mix;

[0048] The high-performance cement concrete is obtained by uniformly adding mixing water to the dry mix while stirring and continuing to stir for 10 minutes.

[0049] The mass ratio of fly ash to silica fume in the ultrafine admixture is 1:1.25.

[0050] The mass ratio of coarse sand, medium sand and fine sand in quartz sand is 1:0.4:0.2.

[0051] The mass ratio of coarse aggregate to fine aggregate in the aggregate is 3:1.

[0052] The mass ratio of the corrugated steel fiber to the polyvinyl alcohol fiber in the fiber composition is 1:0.4.

[0053] Example 3

[0054] Preparation of high performance cement concrete:

[0055] Mix 40 parts of isooctyltriethoxysilane emulsion, 10 parts of polycarboxylic acid water reducer and 200 parts of water to obtain mixing water;

[0056] 700 parts of cement, 250 parts of ultrafine admixture, 1300 parts of quartz sand, 600 parts of aggregate and 120 parts of fiber composition were put into a mixer and stirred for 5 minutes to obtain a dry mix;

[0057] The high-performance cement concrete is obtained by uniformly adding mixing water to the dry mix while stirring and continuing to stir for 10 minutes.

[0058] The mass ratio of fly ash to silica fume in the ultrafine admixture is 1:1.25.

[0059] The mass ratio of coarse sand, medium sand and fine sand in quartz sand is 1:0.5:0.3.

[0060] The mass ratio of coarse aggregate to fine aggregate in the aggregate is 5:2.

[0061] The mass ratio of the corrugated steel fiber to the polyvinyl alcohol fiber in the fiber composition is 1:0.6.

[0062] Comparative Example 1

[0063] Compared with Example 1, the only difference is that no silane emulsion is added.

[0064] Comparative Example 2

[0065] Compared with Example 1, the only difference is that the mass ratio of coarse sand, medium sand and fine sand in the quartz sand is 1:1:1.

[0066] Comparative Example 3

[0067] Compared with Example 1, the only difference is that the mass ratio of coarse aggregate to fine aggregate in the aggregate is 1:1.

[0068] Comparative Example 4

[0069] Compared with Example 1, the only difference is that the mass ratio of the corrugated steel fiber to the polyvinyl alcohol fiber in the fiber composition is 1:1.

[0070] Comparative Example 5

[0071] Compared with Example 1, the only difference is that only coarse quartz sand is used.

[0072] Comparative Example 6

[0073] Compared with Example 1, the only difference is that only fine aggregate is used as aggregate.

[0074] Comparative Example 7

[0075] Compared with Example 1, the only difference is that only corrugated steel fibers are used.

[0076] Test example

[0077] The cement concrete prepared in Example 1 and Comparative Examples 1 to 7 was subjected to conventional curing for 28 days.

[0078] 1.1 Water absorption test

[0079] Referring to GB / T 50081-2019, "Test Methods for Physical and Mechanical Properties of Concrete," the water absorption of cement concrete after conventional curing for 28 days was tested. Water absorption test specimens were cubic specimens with a side length of 100 mm. The specimens were dried in a dryer to constant weight and then immersed in water with the water level 30 mm above the top surface, with supports supporting the bottom of the specimens. Sample weights were measured after immersion for 1 hour, 1 day, and 7 days, recorded as m1, m2, and m3, respectively. Water absorption was calculated using the formula shown in Equation 1.

[0080] Water absorption rate = (m1 or m2 or m3-m0) / m0

[0081] Formula 1

[0082] The weighing method is to take out the sample, wipe off the water stains on the surface and then weigh it. The test results are shown in Table 1.

[0083] Table 1

[0084]

[0085] As can be seen from Table 1, the cement concrete prepared in Example 1 of the present invention has excellent waterproof performance, and as can be seen from Comparative Examples 2 to 7, the gradient compounding of quartz sand and aggregate in the present invention also affects the water absorption rate of cement concrete. It is because the density change caused by the gradient compounding ratio affects the water absorption rate of cement.

[0086] 1.2 Compression and flexural properties

[0087] With reference to GB / T 50081-2019, Test Methods for Physical and Mechanical Properties of Concrete, the mechanical properties of concrete after 28 days of conventional curing were tested. The compressive test specimens used cubic specimens with a side length of 150 mm, and the flexural test specimens used specimens with a size of 150 mm × 150 mm × 600 mm. The test results are shown in Table 2.

[0088] Table 2

[0089]

[0090] It can be seen from the data in Table 2 that the cement concrete prepared in the present application has excellent compressive strength and flexural strength after curing for 28 days, and it can be seen from the data of Comparative Examples 1 to 7 that the raw material ratio relationship of the present application affects the mechanical properties of cement concrete. The compressive strength of Example 1 is slightly lower than that of Comparative Example 1 because the silane emulsion demulsifies and spreads on the surface of the cement particles to form a hydrophobic layer of carbon chains connected by silanol groups, which affects the hydration of the cement and leads to a loss of compressive strength of the concrete. However, the present invention adjusts the mechanical properties of the concrete by adjusting the ratio of other components in conjunction with the silane emulsion, so that the overall compressive strength does not change much, solving the technical problem of a significant decrease in mechanical properties after the addition of silane emulsion. This may be because the gradient-graded raw materials and ultrafine admixtures destroy the silane emulsion coating layer that coats the cement inside the concrete, but do not affect the coating layer on the concrete surface. Therefore, the mechanical properties do not decrease significantly, and the concrete still has excellent hydrophobicity. It can also be seen from the compressive and flexural data of Examples 2 to 7 that when the ratio and raw material selection are changed, the compressive strength and flexural strength decrease significantly.

[0091] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0092] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-performance cement concrete, characterized in that: Calculated by mass, it includes the following components: 600-700 parts of cement, 150-250 parts of ultrafine admixture, 1000-1300 parts of quartz sand, 300-600 parts of aggregate, 100-120 parts of fiber composition, 8-10 parts of water reducer, 10-40 parts of silane emulsion and 150-200 parts of water; The silane emulsion includes one of isobutylene triethoxysilane emulsion, n-octyl triethoxysilane emulsion and isooctyl triethoxysilane emulsion; The ultrafine admixture is made by mixing fly ash and silica fume; The mass ratio of the fly ash to the silica fume is 1:1.25; The fiber composition is formed by mixing steel fibers and polyvinyl alcohol fibers; The quartz sand is a mixture of coarse sand, medium sand and fine sand, with a mass ratio of 1:0.4-0.5:0.2-0.3; The particle size of the coarse sand is between 0.5 and 0.8 mm; The particle size of the medium sand is between 0.3 and 0.5 mm; The particle size of the fine sand is between 0.2 and 0.3 mm; The aggregate is a mixture of coarse aggregate and fine aggregate in a mass ratio of 3-5:1-2; The particle size of the coarse aggregate is between 10 and 15 mm; The particle size of the fine aggregate is between 3 and 5 mm.

2. The cement concrete according to claim 1, characterized in that The mass ratio of the steel fiber to the polyvinyl alcohol fiber is 1:0.4-0.

6.

3. The cement concrete according to claim 1, characterized in that The water reducer is a polycarboxylic acid water reducer.

4. A method for preparing the high-performance cement concrete according to any one of claims 1 to 3, comprising: Evenly mixing the silane emulsion, the water reducing agent and water to obtain mixing water; Put cement, ultrafine admixture, quartz sand, aggregate and fiber composition into a mixer and stir for 5 to 10 minutes to obtain a dry mix; The mixing water is added to the dry mix while stirring, and stirring is continued for more than 10 minutes to obtain the high-performance cement concrete.

5. Use of the high-performance cement concrete according to any one of claims 1 to 3 in construction projects.

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