An underwater non-dispersible concrete and a method for preparing the same

Abstract

The application relates to the technical field of concrete, and discloses underwater non-dispersed concrete and a preparation method thereof. The underwater non-dispersed concrete comprises the following components in parts by weight: cement 350-450 parts, fly ash 40-50 parts, sand 700-800 parts, broken stone 950-1100 parts, water reducing agent 5-12 parts and flocculating agent 10-20 parts. Through the technical scheme, the problem that the underwater non-dispersed concrete has poor fluidity due to the mixing of the flocculating agent in the related art is solved.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to an underwater non-dispersible concrete and its preparation method. Background Technology

[0002] Concrete is one of the main building materials in underwater engineering projects such as bridge foundations, dams, port facilities, and marine structures, and its performance directly affects the construction progress. During construction, when ordinary concrete is poured directly underwater, the cement separates from the aggregate due to the scouring effect of the water flow, resulting in stratification of the poured concrete and affecting the quality of the project.

[0003] Compared to ordinary concrete, underwater non-dispersible concrete incorporates water-soluble polymeric flocculants, which bind cement and aggregates together underwater, preventing separation of cement and aggregates during direct underwater pouring. However, the addition of flocculants increases the viscosity of the concrete, resulting in poor underwater fluidity. Therefore, developing an underwater non-dispersible concrete that combines high fluidity and high anti-dispersion properties is extremely necessary. Summary of the Invention

[0004] This invention proposes an underwater non-dispersible concrete and its preparation method, which solves the problem of poor fluidity caused by the addition of flocculants in underwater non-dispersible concrete in related technologies.

[0005] The technical solution of the present invention is as follows: This invention proposes an underwater non-dispersible concrete, comprising the following components in parts by weight: Cement 350-450 parts, fly ash 40-50 parts, sand 700-800 parts, crushed stone 950-1100 parts, water-reducing agent 5-12 parts, flocculant 10-20 parts. The flocculant comprises polyacrylamide and bentonite in a mass ratio of 3 to 9:1.

[0006] As a further technical solution, the mass ratio of polyacrylamide to bentonite is 4:1.

[0007] In this invention, when the mass ratio of polyacrylamide to bentonite is 4:1, the synergistic effect of the two is further enhanced, thereby further improving the high fluidity and high anti-dispersion properties of underwater non-dispersible concrete.

[0008] As a further technical solution, the weight-average molecular weight of the polyacrylamide is 8 million to 12 million.

[0009] In this invention, polyacrylamide is selected as a flocculant. As a long-chain water-soluble polymer, it can aggregate the components in underwater non-dispersible concrete to form a stable agglomerated structure, thereby improving the high anti-dispersion property of underwater non-dispersible concrete. When the weight-average molecular weight of polyacrylamide is 8 million to 12 million, the high anti-dispersion property of underwater non-dispersible concrete is further improved.

[0010] In this invention, the addition of bentonite improves the fluidity of underwater non-dispersible concrete. The bentonite can be sodium-based bentonite, calcium-based bentonite, or lithium-based bentonite, preferably sodium-based bentonite. When the bentonite is sodium-based, the fluidity of the underwater non-dispersible concrete is further improved.

[0011] As a further technical solution, the sand is medium-coarse sand with a particle size of 0.25~0.5mm.

[0012] As a further technical solution, the particle size of the crushed stone is 5~25mm.

[0013] As a further technical solution, the water-reducing agent is one or more of lignin sulfonate water-reducing agents, naphthalene-based water-reducing agents, and polycarboxylate-based water-reducing agents.

[0014] As a further technical solution, the bentonite is modified bentonite; The modified bentonite raw material comprises the following components in parts by weight: 100 parts bentonite, 50-150 parts triethanolamine, and 3-10 parts sodium polyacrylate.

[0015] In this invention, triethanolamine and sodium polyacrylate are used to modify bentonite, which improves the hydrophilicity of bentonite and reduces the adsorption of water-reducing agents by bentonite, thereby further improving the fluidity of underwater non-dispersible concrete.

[0016] As a further technical solution, the mass ratio of triethanolamine to sodium polyacrylate is 10:1.

[0017] As a further technical solution, the weight-average molecular weight of the sodium polyacrylate is 10 million to 20 million.

[0018] As a further technical solution, the preparation method of the modified bentonite includes the following steps: S1. Disperse bentonite in water to form bentonite slurry; S2. Add acid to the bentonite slurry to activate it, and you will get activated bentonite; S3. Heat the activated bentonite to 30~50℃, add triethanolamine, and react for 2~4 hours to obtain the reaction solution; S4. Add sodium polyacrylate to the reaction solution, heat to 45~70℃, react for 1~3 hours, wash, filter, and dry to obtain modified bentonite. Preferably, the acid is hydrochloric acid or sulfuric acid.

[0019] In this invention, bentonite is first activated with hydrochloric acid or sulfuric acid, and then modified with triethanolamine and sodium polyacrylate. The activation treatment enhances the interaction between bentonite and triethanolamine and sodium polyacrylate.

[0020] The present invention also proposes a method for preparing underwater non-dispersible concrete, comprising the following steps: mixing cement, fly ash, sand, crushed stone, water-reducing agent and flocculant with water to obtain underwater non-dispersible concrete.

[0021] The working principle and beneficial effects of this invention are as follows: In this invention, polyacrylamide and bentonite are mixed in a mass ratio of 3 to 9:1 as flocculants in concrete. The two work synergistically to not only improve the anti-dispersion properties of underwater non-dispersion concrete, but also improve its fluidity, so that the prepared underwater non-dispersion concrete has both high fluidity and high anti-dispersion properties. Detailed Implementation The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] In the following examples and comparative examples, the cement is silicate cement P·O42.5, manufactured by Jidong Cement; the fly ash is Grade II fly ash, manufactured by Tianjin Tongzhou Fly Ash Products Co., Ltd.; the sand is medium-coarse sand with a particle size of 0.25~0.5mm; the crushed stone has a particle size of 5~25mm and originates from Laishui County, Baoding City, Hebei Province; the water-reducing agent is polycarboxylate water-reducing agent with a water reduction rate of 20%; and the molecular weight of sodium polyacrylate is 15 million.

[0023] Example 1 An underwater non-dispersible concrete comprises the following components in parts by weight: The ingredients are: 350 parts cement, 40 parts fly ash, 700 parts sand, 950 parts crushed stone, 5 parts water-reducing agent, and 10 parts flocculant. The flocculant consists of 7.5 parts polyacrylamide (weight-average molecular weight 5 million) and 2.5 parts calcium-based bentonite.

[0024] The preparation method of underwater non-dispersible concrete includes the following steps: mixing cement, fly ash, sand, crushed stone, water-reducing agent and flocculant with water, with a water-cement ratio of 0.4, to obtain underwater non-dispersible concrete.

[0025] Example 2 An underwater non-dispersible concrete comprises the following components in parts by weight: The ingredients are: 405 parts cement, 45 parts fly ash, 745 parts sand, 1000 parts crushed stone, 9 parts water-reducing agent, and 14.4 parts flocculant. The flocculant consists of 10.8 parts polyacrylamide (weight-average molecular weight 5 million) and 3.6 parts sodium bentonite.

[0026] The preparation method of underwater non-dispersible concrete includes the following steps: mixing cement, fly ash, sand, crushed stone, water-reducing agent and flocculant with water, with a water-cement ratio of 0.4, to obtain underwater non-dispersible concrete.

[0027] Example 3 An underwater non-dispersible concrete comprises the following components in parts by weight: The ingredients are: 450 parts cement, 50 parts fly ash, 800 parts sand, 1100 parts crushed stone, 12 parts water-reducing agent, and 20 parts flocculant. The flocculant consists of 16 parts polyacrylamide (weight-average molecular weight 5 million) and 4 parts lithium-based bentonite.

[0028] The preparation method of underwater non-dispersible concrete includes the following steps: mixing cement, fly ash, sand, crushed stone, water-reducing agent and flocculant with water, with a water-cement ratio of 0.4, to obtain underwater non-dispersible concrete.

[0029] Example 4 The only difference between this embodiment and Embodiment 2 is that the flocculant consists of 12.96 parts polyacrylamide (weight average molecular weight 5 million) and 1.44 parts sodium bentonite.

[0030] Example 5 The only difference between this embodiment and Embodiment 2 is that the flocculant consists of 11.52 parts polyacrylamide (weight average molecular weight 5 million) and 2.88 parts sodium bentonite.

[0031] Example 6 The only difference between this embodiment and Example 5 is that the weight-average molecular weight of the polyacrylamide is 14 million.

[0032] Example 7 The only difference between this embodiment and Example 5 is that the weight-average molecular weight of the polyacrylamide is 8 million.

[0033] Example 8 The only difference between this embodiment and Example 5 is that the weight-average molecular weight of the polyacrylamide is 12 million.

[0034] Example 9 The only difference between this embodiment and Embodiment 5 is that the bentonite is modified bentonite. By weight, the raw materials include 100 parts of sodium-based bentonite, 50 parts of triethanolamine, and 3 parts of sodium polyacrylate. The preparation method of the modified bentonite includes the following steps: S1. Disperse sodium-based bentonite in water to prepare a bentonite slurry with a mass concentration of 5%. S2. Activate the bentonite slurry by adding 10% hydrochloric acid to obtain activated bentonite. The amount of hydrochloric acid used is 2% of the bentonite mass. S3. Heat the activated bentonite to 50°C, add triethanolamine and sodium polyacrylate, react for 4 hours, wash, filter, and dry to obtain modified bentonite.

[0035] Example 10 The only difference between this embodiment and Embodiment 9 is that, by weight, the raw materials for the modified bentonite include 100 parts of sodium bentonite, 150 parts of triethanolamine, and 10 parts of sodium polyacrylate.

[0036] Example 11 The only difference between this embodiment and Embodiment 9 is that, by weight, the raw materials for the modified bentonite include 100 parts of sodium bentonite, 50 parts of triethanolamine, and 7 parts of sodium polyacrylate.

[0037] Example 12 The only difference between this embodiment and Embodiment 9 is that, by weight, the raw materials for the modified bentonite include 100 parts of sodium bentonite, 50 parts of triethanolamine, and 5 parts of sodium polyacrylate.

[0038] Example 13 The only difference between this embodiment and Embodiment 12 is that the preparation method of the modified bentonite includes the following steps: S1. Disperse sodium-based bentonite in water to form bentonite slurry; S2. Activate the bentonite slurry by adding 15% hydrochloric acid to obtain activated bentonite. S3. Heat the activated bentonite to 50°C, add sodium polyacrylate, and react for 2 hours to obtain the reaction solution; S4. Add triethanolamine to the reaction solution, heat to 70°C, react for 2 hours, wash, filter, and dry to obtain modified bentonite.

[0039] Example 14 The only difference between this embodiment and Embodiment 12 is that the preparation method of the modified bentonite includes the following steps: S1. Disperse sodium-based bentonite in water to form bentonite slurry; S2. Activate the bentonite slurry by adding 15% hydrochloric acid to obtain activated bentonite. S3. Heat the activated bentonite to 50°C, add triethanolamine, and react for 2 hours to obtain the reaction solution; S4. Add sodium polyacrylate to the reaction solution, heat to 70°C, react for 2 hours, wash, filter, and dry to obtain modified bentonite.

[0040] Example 15 The only difference between this embodiment and Embodiment 12 is that the preparation method of the modified bentonite includes the following steps: S1. Disperse sodium-based bentonite in water to form bentonite slurry; S2. Activate the bentonite slurry by adding 15% hydrochloric acid to obtain activated bentonite. S3. Heat the activated bentonite to 30°C, add triethanolamine, and react for 4 hours to obtain the reaction solution; S4. Add sodium polyacrylate to the reaction solution, heat to 45°C, react for 3 hours, wash, filter, and dry to obtain modified bentonite.

[0041] Comparative Example 1 The only difference between this comparative example and Example 1 is that the flocculant is polyacrylamide (weight-average molecular weight 5 million).

[0042] The fluidity and non-dispersibility of the underwater non-dispersible concrete prepared in Examples 1-15 and Comparative Example 1 were tested, specifically as follows: Flowability: The flowability of underwater non-dispersible concrete was evaluated using one of the methods specified in DL / T5117-2000 "Test Procedure for Underwater Non-dispersible Concrete"—the spread test. Non-dispersibility: The method for evaluating the anti-dispersibility of underwater non-dispersible concrete is the determination of suspended solids content, which is one of the methods specified in DL / T5117-2000 "Test Procedure for Underwater Non-dispersible Concrete". The test results are shown in Table 1 below: Table 1. Test results of underwater non-dispersible concrete prepared in Examples 1-15 and Comparative Example 1

[0043] As can be seen from Table 1, compared with Comparative Example 1, the underwater non-dispersible concrete in Examples 1-15 has increased spread and decreased suspended solids content, indicating that the use of polyacrylamide and bentonite as flocculants not only improves the anti-dispersion properties of underwater non-dispersible concrete, but also improves its fluidity.

[0044] Compared with Examples 2 and 6, the underwater non-dispersible concrete in Examples 7 and 8 has higher spread and lower suspended solids content, indicating that when the weight-average molecular weight of polyacrylamide is 8 million to 12 million, it further improves the fluidity and anti-dispersion properties of underwater non-dispersible concrete.

[0045] Compared with Example 8, the underwater non-dispersible concrete of Examples 9-15 has higher spread and lower suspended solids content. Furthermore, the underwater non-dispersible concrete of Examples 14 and 15 has relatively higher spread and relatively lower suspended solids content. This indicates that modifying bentonite with triethanolamine and sodium polyacrylate, and modifying it with triethanolamine first and then with sodium polyacrylate, further improves the fluidity and anti-dispersion properties of the underwater non-dispersible concrete.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An underwater non-dispersible concrete, characterized in that, The components include the following parts by weight: Cement 350-450 parts, fly ash 40-50 parts, sand 700-800 parts, crushed stone 950-1100 parts, water-reducing agent 5-12 parts, flocculant 10-20 parts. The flocculant comprises polyacrylamide and bentonite in a mass ratio of 4:1; The bentonite is modified bentonite; the raw materials of the modified bentonite include the following components in parts by weight: 100 parts bentonite, 50-150 parts triethanolamine, 3-10 parts sodium polyacrylate; The sodium polyacrylate has a weight-average molecular weight of 10 million to 20 million. The method for preparing the modified bentonite includes the following steps: S1. Disperse bentonite in water to form bentonite slurry; S2. Add acid to the bentonite slurry to activate it, and you will get activated bentonite; S3. Heat the activated bentonite to 30~50℃, add triethanolamine, and react for 2~4 hours to obtain the reaction solution; S4. Add sodium polyacrylate to the reaction solution, heat to 45~70℃, react for 1~3 hours, wash, filter, and dry to obtain modified bentonite.

2. The underwater non-dispersible concrete according to claim 1, characterized in that, The polyacrylamide has a weight-average molecular weight of 8 million to 12 million.

3. The underwater non-dispersible concrete according to claim 1, characterized in that, The bentonite is sodium-based bentonite.

4. The underwater non-dispersible concrete according to claim 1, characterized in that, The sand has a particle size of 0.25~0.5mm; and / or, The particle size of the crushed stone is 5~25mm; and / or, The water-reducing agent is one or more of the following: lignin sulfonate water-reducing agents, naphthalene-based water-reducing agents, and polycarboxylate-based water-reducing agents.

5. The underwater non-dispersible concrete according to claim 1, characterized in that, The mass ratio of triethanolamine to sodium polyacrylate is 10:

1.

6. The underwater non-dispersible concrete according to claim 1, characterized in that, The acid is either hydrochloric acid or sulfuric acid.

7. A method for preparing underwater non-dispersible concrete according to any one of claims 1 to 6, characterized in that, The process includes the following steps: mixing cement, fly ash, sand, crushed stone, water-reducing agent, and flocculant with water to obtain underwater non-dispersible concrete.

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