Concrete ultra-dispersed nano airtight agent as well as preparation method and application thereof

Abstract

The invention provides a concrete ultra-dispersed nano airtight agent. The concrete ultra-dispersed nano airtight agent is prepared from the following raw materials in parts by weight: 20.0 to 30.0 parts of active components, 35.0 to 55.0 parts of compacting components, 2.0 to 5.0 parts of air entraining components, 0.0 to 10.0 parts of water reducing components, 0.0 to 10.0 parts of water retention components and 5.0 to 10.0 parts of dispersing components. The concrete ultra-dispersed nano airtight agent has the effects of improving the compactness of concrete and optimizing the internal pore structure and pore size distribution of the concrete; a water-retaining component is introduced to inhibit water loss in the concrete, keep the humidity in the concrete stable and guarantee gas permeation in the concrete; the dispersion component is introduced, so that the problem that the powder material is difficult to disperse in the concrete construction process is solved, and the working performance in the concrete construction process is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly relates to a concrete super-dispersed nano airtight agent, a preparation method thereof and an application thereof. Background Art

[0002] During the construction and service process of tunnel engineering concrete structures, they face challenges from harmful gases (CH4, CO, CO2, H2S), and there is a risk of gas penetration when tunnel engineering passes through coal-bearing strata. Therefore, higher requirements are imposed on the airtightness of concrete. Currently, there are mainly two types of technologies for improving the airtightness of concrete: (1) Adopting the "low water-binder ratio + mineral admixture technology": The low water-binder ratio ensures the denseness of the concrete matrix and reduces the porosity inside the concrete. Incorporating mineral admixtures into the concrete can cause secondary hydration and optimize the pore size distribution inside the concrete; (2) Incorporating a concrete airtight agent: Incorporating a certain amount of airtight agent during concrete construction can improve the airtight performance of the concrete, enhance the denseness of the concrete, and strengthen the low-permeability effect of the concrete.

[0003] Currently, there are mainly two types of airtight agents on the market. One type is a liquid airtight agent with a water-reducing agent as the main functional component supplemented by workability-improving components. By reducing the water-binder ratio and improving workability, it can enhance the airtightness of concrete, but there are problems such as limited improvement in airtightness and an increased risk of segregation and bleeding of fresh concrete. The other type is a powder airtight agent with highly active mineral admixtures as the main functional component. By having the mineral admixtures participate in the cement hydration reaction to optimize the pore structure, it can achieve an improvement in the airtightness of concrete, but there are problems such as difficulty in dispersing ultra-fine powders, easy increase in the viscosity of concrete, and deterioration of construction performance.

[0004] Patent 202210167444.9 discloses a chlorine-free concrete airtight agent and a preparation method thereof, which include a polycarboxylate-based water-reducing agent, a sulfonate water-reducing agent, a chain-type alkanolamine, a retarder, an anti-freezing and rust-inhibiting agent, an anti-foaming agent and water. The airtight agent obtained by the raw materials and method of the present invention, when added to concrete, can change the pore structure of the concrete, reduce the air bubble spacing coefficient, increase the denseness of the concrete, improve the ability of the concrete to resist salt erosion and freeze-thaw damage, enhance the mechanical properties and durability of the concrete, and extend the service life of the concrete.

[0005] For airtight agent products for engineering requirements, only filling the internal pore structure of concrete with reaction products through chemical reactions can not only fail to effectively reduce the porosity, but may also cause changes in the pH of the concrete pore solution and hydration products, ultimately leading to other durability problems of the concrete structure. Therefore, in engineering structures with strict requirements for concrete airtightness, in order to balance the improvement of concrete compactness, pore structure optimization and good durability, powder materials are preferably used for airtight agent products, which can optimize the pore structure of the matrix through secondary hydration and pozzolanic effect, and improve the compactness of the matrix through filling effect. If the problem of difficult dispersion of powder airtight agent products, which affects the workability of concrete, can be solved, powder airtight agents will be widely used. Summary of the Invention

[0006] Aiming at the above-mentioned deficiencies and other problems in the prior art, the present invention provides a super-dispersed nano airtight agent for concrete, its preparation method and application, which are mainly used in structural engineering with gas pressure, and have the effects of improving the compactness of concrete, optimizing the internal pore structure and pore size distribution of concrete; and introducing a dispersion component to solve the problem of difficult dispersion of powder materials during the concrete construction process, so as to ensure the workability during the concrete construction process.

[0007] A super-dispersed nano airtight agent for concrete comprises the following raw materials in parts by weight: 20.0 - 30.0 parts of active component, 35.0 - 55.0 parts of compacting component, 2.0 - 5.0 parts of air-entraining component, 0.0 - 10.0 parts of water-reducing component, 0.0 - 10.0 parts of water-retaining component, and 5.0 - 10.0 parts of dispersion component. Among them, the active component, compacting component, dispersion component and air-entraining component are core components to ensure that the concrete incorporated with the super-dispersed nano airtight agent has low gas permeability. The water-reducing component and water-retaining component are functional components to ensure the construction performance of concrete and the internal environment with low gas permeability.

[0008] Preferably, the super-dispersed nano airtight agent for concrete comprises the following raw materials in parts by weight: 25 parts of active component, 50 parts of compacting component, 5 parts of air-entraining component, 5 parts of water-reducing component, 5 parts of water-retaining component, and 10 parts of dispersion component.

[0009] The above-mentioned active component is any one of nano-silica and nano-aluminum oxide. The active component has strong pozzolanic activity and can react with calcium hydroxide in the hydration products of cement in concrete to generate C-S-H gel, filling the fine pores in the hardened concrete paste, thereby reducing the porosity in the concrete paste, and further making the hardened concrete more compact and with higher strength.

[0010] The above-mentioned compacting component is calcium carbonate powder with a mesh number not less than 800 meshes. During the cement hydration process, calcium carbonate powder can promote cement hydration due to the nucleation effect, and at the same time, the fine calcium carbonate particles can fill the pores and fine cracks of concrete, improving the compactness and impermeability of concrete.

[0011] The above-mentioned dispersing component is poly-sulfonic acid or sodium dodecyl sulfonate. The introduction of the dispersing component solves the problem of difficult dispersion of powder materials during the concrete construction process.

[0012] The combined use of the active component and the compacting component, with the assistance of the dispersing component, makes the concrete matrix more compact, resulting in a significant reduction in the gas permeability inside the concrete.

[0013] The above-mentioned air-entraining component is one or a mixture of polyoxyethylene fatty alcohol ether, sodium polyoxyethylene fatty alcohol sulfonate, and sodium fatty alcohol sulfate.

[0014] The combined action of the active component and the compacting component makes the pores inside the concrete smaller. Then, in combination with the air-entraining component, the pore structure is transformed into a large number of tiny closed air bubbles, further reducing the gas permeability inside the concrete.

[0015] The above-mentioned water-retaining component is one or a mixture of dimethyl silicone, epoxy-modified polysiloxane, and isobutene triethoxysilane. The introduction of the water-retaining component inhibits the loss of moisture inside the concrete, maintains the stability of the humidity inside the concrete, and provides guarantee for the low gas permeability inside the concrete.

[0016] The above-mentioned water-reducing component is one or a mixture of polycarboxylate water-reducing agent and amino sulfonate water-reducing agent.

[0017] On the one hand, the water-reducing component and the water-retaining component are functional components, providing guarantee for the construction performance of the concrete and the internal environment with low gas permeability; on the other hand, the air-entraining component, the water-reducing component, and the dispersing component act synergistically, which can reduce the flow resistance and cohesiveness of the concrete mixture, make the active component and the compacting component disperse more evenly in the spatial structure of the concrete, and play their secondary hydration and filling roles more effectively. At the same time, the chemical molecular structures of the three components are similar and they have good compatibility.

[0018] A preparation method of a concrete super-dispersing nano airtight agent includes the following steps:

[0019] (1) Pour the active component and the compacting component into a double-motion powder mixer, and control the barrel to rotate slowly at a speed of 10 ± 1 r / min for 10 ± 5 min; avoid the floating movement of ultra-fine powder;

[0020] (2) Open the blades of the double-motion powder mixer to rotate, with a rotation speed of 20 ± 2 r / min, and run for 10 ± 5 min. After the heavy and light powders are mixed evenly, stop the machine to obtain a mixture M1;

[0021] (3) Mix the air-entraining component, the water-reducing component, the water-retaining component, and the dispersing component with the mixture M1, and open the blades of the double-motion powder mixer to rotate. After running at a speed of 20 ± 2 r / min for 10 ± 5 min, a concrete super-dispersing nano airtight agent is obtained.

[0022] When the above concrete super-dispersed nano airtight agent is applied to the cement concrete system, its dosage is 5.0% - 10.0% of the total mass of the cementitious materials.

[0023] This application has the following advantages compared with the prior art:

[0024] (1) The core components act synergistically to ensure low gas permeability inside the concrete. ① The combined action of the active component, the densifying component and the dispersing component makes the pores inside the concrete finer. ② The air-entraining component transforms the pore structure into a large number of tiny closed air bubbles. The active component, the densifying component, the dispersing component and the air-entraining component act synergistically and gradually reduce the gas permeability in the concrete from multiple levels and angles.

[0025] (2) The functional components have similar chemical molecular structures and good compatibility, assisting the core components to exert their functions and ensuring the working performance of the concrete and the humidity environment with low gas permeability.

[0026] (3) The composite of organic and inorganic materials not only ensures the construction performance of the concrete but also ensures low medium permeability after the concrete sets and hardens. Description of the Drawings

[0027] Figure 1 It is the distribution diagram of the internal pore structure of the reference group concrete and the concrete incorporated with the super-dispersed nano airtight agent in Example 1;

[0028] Figure 2 It is the internal pore structure diagram of the concrete after incorporating the airtight agents of Example 1, Comparative Example 1, Comparative Example 3 and Comparative Example 6 of this application. Detailed Embodiments

[0029] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] The dosage parts of each raw material in the concrete super-dispersed nano airtight agent used in each embodiment are as shown in Table 1 below. Each raw material is a commercially available product:

[0031] Table 1

[0032]

[0033]

[0034] Test Example:

[0035] The mix ratio of C40 portland cement-fly ash concrete is adopted. In this test, the cementitious materials are ordinary portland cement of grade PO42.5 and class I fly ash; the fine aggregate is river sand with a fineness modulus of 2.8; the coarse aggregate is basalt with a particle size of 5-15 mm and an apparent density of 2750 kg / m 3 . The airtight agent is prepared by using the airtight agents in the above-mentioned examples and comparative examples, and the dosage is 10% of the mass of the cementitious materials.

[0036]

[0037] According to the standards of TB 10424-2018 "Acceptance Criteria for Construction Quality of Railway Concrete Engineering", TB 10120-2019 "Technical Specifications for Railway Gas Tunnels", and T / CECS10314-2023 "Concrete Airtight Agent", the performance of the above-prepared airtight agent is evaluated. The test results are shown in Table 2 below:

[0038] Table 2

[0039]

[0040] It can be found from Example 1 and Comparative Examples 1-2 in Table 2 that the active components and dense components in the super-dispersed nano airtight agent can significantly improve the density of the concrete matrix, increase the compressive strength of the concrete, thereby reducing the permeability of the medium in the concrete, manifested as a decrease in the air permeability coefficient ratio and electric flux ratio and an increase in the corrosion resistance coefficient. Figure 2 It can be seen that when the active components are removed from the super-dispersed nano airtight agent, the porosity in the concrete increases significantly.

[0041] It can be found from Example 1 and Comparative Example 3 in Table 2 that the air-entraining components in the super-dispersed nano airtight agent can transform the pore structure into a large number of tiny closed bubbles, manifested as an obvious decrease in the air permeability coefficient ratio. Figure 2 It can be seen that when the air-entraining components are removed from the super-dispersed nano airtight agent, the pore structure distribution in the concrete is uneven and there are many connected large pores.

[0042] It can be found from Example 1 and Comparative Example 6 in Table 2 that the dispersing components in the super-dispersed nano airtight agent can disperse the active and dense components evenly, manifested as an obvious increase in strength and an obvious decrease in the air permeability coefficient ratio. Figure 2 It can be seen that when the dispersing components are removed from the super-dispersed nano airtight agent, the active components and dense components are unevenly dispersed and agglomerated, manifested as an uneven distribution of the pore structure inside the concrete.

[0043] The super-dispersed nano airtight agent for concrete obtained in this application can optimize the pore structure and pore size distribution inside the concrete to a certain extent, significantly improve the density of the concrete matrix, increase the compressive strength of the concrete, thereby reducing the permeability of the medium in the concrete, and has good practicability.

[0044] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A super-dispersed nano airtight agent for concrete, characterized in that, It comprises raw materials in the following parts by weight: 20.0 to 30.0 parts of active component, 35.0 to 55.0 parts of dense component, 2.0 to 5.0 parts of air-entraining component, 0.0 to 10.0 parts of water-reducing component, 0.0 to 10.0 parts of water-retaining component, and 5.0 to 10.0 parts of dispersing component.

2. The super-dispersed nano airtight agent for concrete according to claim 1, wherein It comprises raw materials in the following parts by weight: 25 parts of active component, 50 parts of dense component, 5 parts of air-entraining component, 5 parts of water-reducing component, 5 parts of water-retaining component, and 10 parts of dispersing component.

3. The super-dispersed nano airtight agent for concrete according to claim 1, characterized in that: The active component is any one of nano-silica and nano-alumina.

4. The super-dispersed nano airtight agent for concrete according to claim 1, wherein: The dense component is calcium carbonate powder with a mesh number of not less than 800 meshes.

5. The super-dispersed nano airtight agent for concrete according to claim 1, characterized in that: The air-entraining component is any one of fatty alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene sulfonate, and sodium lauryl sulfate.

6. The super-dispersed nano airtight agent for concrete according to claim 1, wherein: The water-reducing component is one or a mixture of two of polycarboxylate water reducer and amino sulfonate water reducer.

7. A super-dispersed nano airtight agent for concrete according to claim 1, characterized in that: The water-retaining component is one or a mixture of dimethyl silicone, epoxy modified polysiloxane, and isobutene triethoxysilane.

8. The super-dispersed nano airtight agent for concrete according to claim 1, characterized in that: The dispersing component is poly sulfonic acid or sodium dodecyl sulfonate.

9. A preparation method of a concrete super-dispersed nano airtight agent according to any one of claims 1-8, characterized in that, It comprises the following steps: (1) Pour the active component and the dense component into a double-motion powder mixer, and control the barrel to rotate slowly at a speed of 10 ± 1 r / min for 10 ± 5 min; (2) Open the blades of the double-motion powder mixer to rotate, with a rotation speed of 20 ± 2 r / min. After running for 10 ± 5 min, stop to obtain mixture M1; (3) Mix the air-entraining component, the water-reducing component, the water-retaining component, and the dispersing component with mixture M1, and open the blades of the double-motion powder mixer to rotate. After running at a speed of 20 ± 2 r / min for 10 ± 5 min, a super-dispersed nano-airtight agent for concrete is obtained.

10. The application method of a concrete super-dispersed nano airtight agent according to any one of claims 1-8, characterized in that: When the super-dispersed nano-airtight agent for concrete is applied to a cement concrete system, its dosage is 5.0% to 10.0% of the total mass of the cementitious materials.

Images