Airtight machine-made sand concrete and preparation method thereof

Abstract

The present invention relates to the field of construction technology and provides an airtight machine-made sand concrete and a preparation method thereof. When the raw materials for preparing the concrete include machine-made sand, crushed stone, cement, a powder admixture mainly composed of silica fume, fly ash, an expansive agent, stone powder and a powder water reducer, and a special admixture mainly composed of a polycarboxylic acid water reducer, a retarder, an air entraining agent, a defoamer, a foam stabilizer and water, the construction workability and airtightness of the airtight machine-made sand concrete are significantly improved. The synergistic combination of the powder admixture and the special admixture ensures that the obtained airtight machine-made sand concrete has low air loss, stable mechanical properties and a low air permeability coefficient. The system does not rely on high-cost airtight agents, provides a new airtight machine-made sand concrete, is particularly suitable for use in tunnels, and has very important technical significance.

Description

Technical Field

[0001] The present invention relates to the field of construction technology, and in particular to airtight machine-made sand concrete and a preparation method thereof. Background Art

[0002] Tunnels play a vital role in shortening travel distances, increasing transportation capacity, and reducing accidents. However, when the mountain through which tunnels are traversed is composed of coal seams containing gas, if the tunnel lining is not dense, the gas and other harmful gases in the coal seams will leak through the tunnel lining and into the tunnel. When the gas accumulates to a certain concentration, it will cause an explosion, causing great harm to tunnel construction, vehicle operation, and the lives and property of passengers. In tunnel construction, airtight concrete is often used to ensure the safety of engineers and users. Due to the current scarcity of river sand resources, the use of manufactured sand in concrete production is becoming a trend. However, the sharp particle shape of manufactured sand significantly increases the air permeability coefficient of the produced airtight concrete, which cannot meet the requirements of tunnel construction.

[0003] To address this issue, patent application CN114133190A describes airtight concrete and its preparation method. The premix is ​​pre-mixed with 800-900 parts of manufactured sand, 950-1050 parts of crushed stone, 275-320 parts of cement, 65-100 parts of fly ash, 6-10 parts of admixture, 25-30 parts of airtight agent, and 150-160 parts of water. The premix is ​​then uniformly stirred to produce airtight concrete. Using manufactured sand as the primary raw material, the method proposes using a specific airtight agent, controlling the ratio of coarse and fine aggregates, using an expansion agent, and pre-treating the crushed stone and manufactured sand at a speed of at least 1500 rpm for 30-60 minutes. This method increases strength and reduces air permeability, thereby achieving the mechanical strength of river sand while increasing airtightness and impermeability, meeting the requirements of tunnel construction. However, in actual application, the processing of crushed stone and machine-made sand is difficult to control, and energy consumption increases and production efficiency decreases. In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide an airtight machine-made sand concrete and a preparation method thereof in response to the above-mentioned problems. The present invention prepares airtight machine-made sand concrete with stable workability and excellent airtightness by utilizing a specific raw material composition, especially the control of stone powder, the use of powder admixtures and special admixtures.

[0005] When the present invention uses machine-made sand instead of river sand to prepare airtight concrete, the key application indicators of the prepared airtight machine-made sand concrete, such as the air permeability coefficient and air loss, are difficult to control due to the structural characteristics of the machine-made sand. After a large number of experimental studies, it was found that when preparing airtight machine-made sand concrete, if an appropriate amount of foam stabilizer is added, the airtightness of the airtight machine-made sand concrete is significantly improved. After further research, it was clarified that the airtight machine-made sand concrete and its preparation method provided by the present invention, when machine-made sand, crushed stone, cement, powder mainly composed of silica fume, fly ash, expansion agent, stone powder and powder water reducer, are used. The concrete is prepared from raw materials consisting of a solid admixture and a special admixture mainly consisting of a polycarboxylic acid water-reducing agent, a retarder, an air entraining agent, a defoamer, a foam stabilizer and water. The construction workability and air tightness of the airtight machine-made sand concrete are significantly improved. In particular, the design of the foam stabilizer in the special admixture, the stone powder in the powder admixture and the total stone powder content in the raw materials solves the dispersion problem of silica fume in the mixed system during the construction process. Specifically, the obtained airtight machine-made sand concrete has low air loss, stable mechanical properties and low permeability coefficient, is particularly suitable for use in tunnels, and has very important technical significance.

[0006] The present invention provides an airtight machine-made sand concrete. The raw materials for preparing the concrete include, by weight:

[0007] 800-900 parts of machine-made sand;

[0008] 900-1100 parts of crushed stone;

[0009] 270-320 parts of cement;

[0010] 85-105 parts of powder admixture;

[0011] 3.7 to 10 parts of admixture;

[0012] 148-166 parts water;

[0013] The powder admixture comprises:

[0014] 8-13 parts of silica fume;

[0015] 65-80 parts of fly ash;

[0016] 4-7 parts of expansion agent;

[0017] 8-13 parts of stone powder;

[0018] 0.5-1.5 parts of powder water reducer;

[0019] The special admixtures include:

[0020] 300-500 parts of polycarboxylate water reducer;

[0021] 10-30 parts of retarder;

[0022] 1 to 10 parts of air-entraining agent;

[0023] 1 to 5 parts of defoaming agent;

[0024] 5-10 parts of foam stabilizer;

[0025] 445-683 parts of water;

[0026] The total weight proportion of the stone powder in the raw materials is 3.8-5.5%.

[0027] In the research of the present invention, it was also found that the total content of stone powder in the raw materials has a great influence on the construction and workability of the airtight machine-made sand concrete during mixing. If the stone powder content is too high, the concrete viscosity will be higher. If the stone powder content is too low, the concrete workability will be poor. Under normal circumstances, machine-made sand will inevitably contain a certain amount of stone powder. The results of the experiment showed that: when the stone powder content in the machine-made sand is low, by adding an appropriate amount of stone powder to the powder admixture, on the basis of the effect of the foam stabilizer, the dispersion stability of silica fume is further improved, which is very helpful to the overall improvement of the airtight machine-made sand concrete, especially the improvement of airtightness.

[0028] Preferably, the special admixture is composed of the following components in parts by mass:

[0029] 300-500 parts of polycarboxylic acid water reducer, 10-30 parts of retarder, 1-10 parts of air entraining agent, 1-5 parts of defoamer, 5-10 parts of foam stabilizer and 445-683 parts of water.

[0030] Preferably, the powder admixture consists of the following components in parts by mass:

[0031] 8-13 parts of silica fume, 65-80 parts of fly ash, 4-7 parts of expansion agent, 8-13 parts of stone powder and 0.5-1.5 parts of powder water reducer.

[0032] According to the airtight machine-made sand concrete provided by the present invention, the foam stabilizer is one or more of silicone resin polyether emulsion, calcium stearate, cellulose and xanthan gum.

[0033] According to the airtight machine-made sand concrete provided by the present invention, the air-entraining agent is one or more of rosin resins, alkyl sulfonates, saponins and polyethers.

[0034] According to the airtight machine-made sand concrete provided by the present invention, the stone powder is 200-300 mesh stone powder.

[0035] According to the airtight machine-made sand concrete provided by the present invention, the machine-made sand is medium sand, and the machine-made sand contains 10-15% by mass of stone powder.

[0036] According to the airtight machine-made sand concrete provided by the present invention, the raw materials for preparing the concrete include, by weight:

[0037] 812 parts of machine-made sand;

[0038] 1000 pieces of crushed stone;

[0039] 303 parts of cement;

[0040] 85-105 parts of powder admixture;

[0041] 5.6 parts of admixture;

[0042] 155 parts water;

[0043] The powder admixture comprises:

[0044] 8-13 parts of silica fume;

[0045] 65-75 parts of fly ash;

[0046] 5-7 parts of expansion agent;

[0047] 8-13 parts of stone powder;

[0048] 0.5-1.5 parts of powder water reducer;

[0049] The special admixtures include:

[0050] 400 parts of polycarboxylate water reducer;

[0051] 20 parts of retarder;

[0052] 1 to 10 parts of air-entraining agent;

[0053] 1 to 5 parts of defoaming agent;

[0054] 5-10 parts of foam stabilizer;

[0055] 445-683 parts of water.

[0056] The present invention also provides a method for preparing the airtight machine-made sand concrete as described above, comprising mixing machine-made sand, crushed stone, cement, powder admixture and a portion of water to obtain a premix; and mixing another portion of water and a special admixture into the premix to obtain the airtight machine-made sand concrete.

[0057] According to the method for preparing the airtight machine-made sand concrete provided by the present invention, the powder admixture is obtained by mixing silica fume, fly ash, an expansive agent, stone powder and a powder water reducer.

[0058] And / or, the special admixture is obtained by first mixing and dissolving a polycarboxylate water reducer and a foam stabilizer, then adding a retarder and water, and finally adding an air entraining agent and a defoamer.

[0059] The present invention also provides the use of the airtight machine-made sand concrete as described above; preferably, the airtight machine-made sand concrete is used in a tunnel.

[0060] The present invention provides an airtight machine-made sand concrete and a preparation method thereof. Concrete is prepared from raw materials consisting of machine-made sand, crushed stone, cement, powder admixture and special admixture under a specific formula. The construction workability and airtightness of the airtight machine-made sand concrete are significantly improved. In particular, the design of the foam stabilizer in the special admixture, the stone powder in the powder admixture and the total stone powder content in the raw materials solves the dispersion of silica fume in the mixed system during the construction process. Specifically, the obtained airtight machine-made sand concrete has low air loss, stable mechanical properties and low permeability coefficient, is particularly suitable for use in tunnels, and has very important technical significance.

[0061] Specifically, the powder admixture in the present invention can improve the density of concrete, reduce the shrinkage of concrete, thereby reducing the gas permeability of concrete and improving the durability of concrete; and the special admixture can reduce the large pores generated in the production process of airtight machine-made sand concrete, introduce a large number of tiny closed bubbles, reduce the connected pores, and at the same time improve the stability of tiny bubbles, thereby optimizing the bubble structure of concrete and reducing gas permeability; in addition, the synergistic effect of the special admixture and the powder admixture can significantly optimize the workability and workability stability of machine-made sand concrete and improve the dispersion stability of silica fume. DETAILED DESCRIPTION

[0062] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0063] Unless otherwise specified, the parameter information of each substance in the embodiments of the present invention is as follows:

[0064]

[0065]

[0066] Examples 1A to 3A Powder Admixtures

[0067] A method for preparing a powder admixture, comprising the following steps:

[0068] (1) Weigh the following components in parts by mass:

[0069] 8-13 parts of silica fume, 65-80 parts of fly ash, 4-7 parts of expansion agent, 8-13 parts of stone powder and 0.5-1.5 parts of powder water reducer.

[0070] (2) The prepared components were stirred in a double-motion mixer for 10 minutes until uniformly mixed to obtain a powder admixture.

[0071] The specific formulas of the powder admixtures in Examples 1A to 3A are shown in the table below.

[0072] name Example 1A Example 2A Example 3A silica fume 13 servings 10 servings 8 servings fly ash 70 servings 70 servings 70 servings expansion agent 6 servings 6 servings 6 servings Stone powder 8 servings 10 servings 13 servings Powder water reducer 0.5 serving 0.5 serving 0.5 serving

[0073] Examples 1B to 3B admixtures

[0074] A method for preparing an admixture, comprising the following steps:

[0075] (1) Weigh the following components in parts by mass:

[0076] 300-500 parts of polycarboxylic acid water reducer, 10-30 parts of retarder, 1-10 parts of air entraining agent, 1-5 parts of defoamer, 5-10 parts of foam stabilizer and 445-683 parts of water.

[0077] (2) First, place the polycarboxylate water reducer and foam stabilizer in a liquid mixer and force stir for 15 minutes until they are completely dissolved. Then, add water and retarder into the liquid mixer and force stir for 15 minutes until they are evenly mixed. Then, add the air entraining agent and defoaming agent into the liquid mixer and circulate for 1 hour using a circulating pump to prepare the admixture.

[0078] The specific formulas of the admixtures in Examples 1B to 3B are shown in the table below.

[0079] name Example 1B Example 2B Example 3B Polycarboxylate water reducer 400 copies 400 copies 400 copies Retarder (sugar) 20 servings 20 servings 20 servings Air-entraining agent (AE-Ⅱ) 2 servings 5 servings 9 servings Defoaming agent (polyether) 1 serving 3 servings 5 servings Foam stabilizer (YH-556) 6 servings 8 servings 10 servings water 571 copies 564 copies 556 copies

[0080] Examples 1C to 3C Airtight Machine-Made Sand Concrete

[0081] A method for preparing airtight machine-made sand concrete, comprising the following steps:

[0082] (1) Weigh the following components in parts by mass:

[0083] 800-900 parts of machine-made sand, 900-1100 parts of crushed stone, 270-320 parts of cement, 85-105 parts of the powder admixture of Examples 1A-3A, 3.7-10 parts of the admixture of Examples 1B-3B, and 148-166 parts of water.

[0084] (2) Put machine-made sand, crushed stone, cement, powder admixture and 80% of water into a forced mixer and stir for 1 minute to obtain a mixture. Then put the remaining water and admixtures into the forced mixer and stir for 1.5 minutes to obtain an airtight machine-made sand concrete.

[0085] The specific formulas of the airtight machine-made sand concrete in Examples 1C to 3C are shown in the table below.

[0086]

[0087]

[0088] Comparative Example 1

[0089] A method for preparing airtight machine-made sand concrete, wherein the steps are substantially the same as those of Example 2C, except that the powder admixture in Example 2A is replaced by fly ash.

[0090] Comparative Examples 2-3

[0091] A method for preparing airtight machine-made sand concrete, comprising the following steps:

[0092] (1) Preparation of powder admixture: basically the same as in Example 2A.

[0093] (2) Preparation of admixture: The admixture used is basically the same as that in Example 2B, except that the specific formula of the admixture is as follows:

[0094] name Comparative Example 2 Comparative Example 3 Polycarboxylate water reducer 400 copies 400 copies Retarder (sugar) 20 servings 20 servings Air-entraining agent (AE-Ⅱ) 5 servings 5 servings Defoaming agent (polyether) 3 servings 3 servings Foam stabilizer (YH-556) 0 copies 20 servings water 572 copies 552 copies

[0095] (3) Preparation of airtight machine-made sand concrete: The process is basically the same as Example 2C, except that the admixture is replaced by the admixture obtained in step (2).

[0096] Comparative Example 4

[0097] A method for preparing airtight machine-made sand concrete, the steps of which are basically the same as those of Example 2C, except that the machine-made sand in Example 2C is replaced with machine-made sand with a stone powder content of 7%, and the total mass proportion of the stone powder in the raw material is about 2.8%.

[0098] Comparative Example 5

[0099] A method for preparing airtight machine-made sand concrete, the steps of which are basically the same as those of Example 2C, with the only difference being that the machine-made sand in Example 2C is replaced with machine-made sand with a stone powder content of 20%, and the total mass proportion of the stone powder in the raw material is approximately 7.2%.

[0100] The machine-made sand concretes prepared in Examples 1C to 3C and Comparative Examples 1 to 5 were tested using the following test methods. The test methods and results are as follows:

[0101] Railway Concrete Engineering Construction Quality Acceptance Standard (TB 10424-2018);

[0102] High-Integrity Containers for Low and Intermediate Level Radioactive Waste - Concrete Containers (GB36900.2);

[0103] Standard for Test Methods for Long-term Properties and Durability of Ordinary Concrete (GB 50082-2009);

[0104]

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An airtight machine-made sand concrete, characterized in that: The raw materials for preparing the concrete include, by weight: ； The total mass percentage of stone powder in the raw materials is 3.8-5.5%; the mass percentage of stone powder in the machine-made sand is 10-15%.

2. The airtight machine-made sand concrete according to claim 1, characterized in that: The foam stabilizer is one or more of silicone resin polyether emulsion, calcium stearate, cellulose and xanthan gum.

3. The airtight machine-made sand concrete according to claim 1, characterized in that: The air entraining agent is one or more of rosin resins, alkyl sulfonates, saponins and polyethers.

4. The airtight machine-made sand concrete according to claim 2, characterized in that: The air entraining agent is one or more of rosin resins, alkyl sulfonates, saponins and polyethers.

5. The airtight machine-made sand concrete according to any one of claims 1 to 4, characterized in that: The stone powder is 200-300 mesh stone powder.

6. The airtight machine-made sand concrete according to any one of claims 1 to 4, characterized in that: The machine-made sand is medium sand.

7. The airtight machine-made sand concrete according to claim 5, characterized in that: The machine-made sand is medium sand.

8. The airtight machine-made sand concrete according to any one of claims 1 to 4 and 7, characterized in that: The raw materials for preparing the concrete include, by weight: 。 9. The airtight machine-made sand concrete according to claim 5, characterized in that: The raw materials for preparing the concrete include, by weight: 。 10. The airtight machine-made sand concrete according to claim 6, characterized in that: The raw materials for preparing the concrete include, by weight: 。 11. The method for preparing airtight machine-made sand concrete according to any one of claims 1 to 10, characterized in that: The machine-made sand, crushed stone, cement, powder admixture and a portion of water are mixed to obtain a premix; the other portion of water and a special admixture are mixed into the premix to prepare airtight machine-made sand concrete.

12. The method for preparing airtight machine-made sand concrete according to claim 11, characterized in that: The powder admixture is obtained by mixing silica fume, fly ash, expansion agent, stone powder and powder water reducer.

13. The method for preparing airtight machine-made sand concrete according to claim 11, characterized in that: The special admixture is obtained by first mixing and dissolving a polycarboxylic acid water reducer and a foam stabilizer, then adding a retarder and water, and finally adding an air entraining agent and a defoaming agent.

14. Use of the airtight machine-made sand concrete according to any one of claims 1 to 10, wherein the airtight machine-made sand concrete is used in a tunnel.

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