Underwater anti-dispersion concrete based on monomer auto-polymerization and preparation method thereof

Abstract

The invention belongs to the technical field of building materials, and relates to an underwater anti-dispersion concrete design based on monomer auto-polymerization and a preparation method thereof. The concrete comprises the following components in parts by weight: 20-40 parts of a polymeric monomer; 0.2 to 0.4 part of a cross-linking agent; 0.5 to 0.8 part of an initiator; 300 to 400 parts of Portland cement; 700 to 800 parts of river sand; 1100 to 1200 parts of broken stone; 160 to 200 parts of water; according to the preparation method, a water reducing agent is not added, and the self-polymerization reaction of the monomers is accurately controlled, specifically, the dosage of an initiator is controlled, and the self-polymerization reaction of the monomers is controlled in a dropwise adding manner, so that the water-resistant dispersibility of the concrete in a plastic stage is remarkably improved; meanwhile, no polymerization reaction occurs, and a high-molecular polymer with a short chain segment can generate a lubricating effect among cement particles, so that the flowability and constructability of the concrete can be effectively maintained.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials and relates to underwater anti-dispersion concrete based on monomer self-polymerization and a preparation method thereof. Background Art

[0002] With the growing demand for marine engineering, bridge construction, and other underwater construction projects, the application of underwater concrete is becoming increasingly widespread. Conventional underwater concrete faces challenges in practical use, including poor dispersion and unstable performance. Especially in underwater construction environments, this dispersion often leads to insufficient strength and construction difficulties. Therefore, improving the dispersion resistance and performance of underwater concrete has long been a key topic in concrete material research.

[0003] Currently, much research is focused on improving the anti-dispersion properties of underwater concrete. Some solutions include adding water reducers and viscosity enhancers. However, the combined use of these additives often results in incompatibility, leading to a decrease in the concrete's performance and even affecting its ultimate mechanical properties. Furthermore, the use of polymers to enhance concrete's anti-dispersion properties is also a widely researched area. However, the application of traditional polymers often fails to balance anti-dispersion and performance, poses a risk of ineffectively controlling polymerization reactions, and can compromise other concrete properties, such as strength or crack resistance.

[0004] Monomer self-polymerization technology has gained increasing attention in recent years. This technology promotes monomer polymerization under controlled conditions, generating a high-molecular-weight polymer network that effectively enhances concrete's resistance to water dispersion. Compared to traditional polymer modification methods, monomer self-polymerization not only ensures concrete's resistance to water dispersion but also avoids incompatibility issues between additives without compromising performance.

[0005] Therefore, how to design underwater anti-dispersion concrete through monomer autopolymerization to improve water dispersion resistance while maintaining good working performance has become a hot topic of current research. The present invention introduces raw materials such as polymer monomers, crosslinking agents, and initiators, and utilizes monomer autopolymerization to generate a high molecular polymer network, significantly improving the water dispersion resistance of underwater concrete and optimizing its working performance on this basis. This avoids the compatibility issues when traditional water reducers and tackifiers are used together, providing a new approach for the development of underwater anti-dispersion concrete. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a design and preparation method of underwater anti-dispersion concrete based on monomer self-polymerization.

[0007] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0008] An underwater anti-dispersion concrete based on monomer self-polymerization, comprising the following components and contents in parts by weight:

[0009]

[0010]

[0011] Furthermore, the polymerizable monomer is one or more of acrylic acid, acrylamide and 2-acrylamide-2-methylpropane sulfonic acid.

[0012] There are significant differences in the functional groups and polymerization activities of the three monomers. By adjusting the addition ratio of each monomer, the affinity of the polymer network to cement particles and the amount of small fragment polymers generated can be significantly affected, thereby regulating the working performance of concrete.

[0013] Furthermore, the cross-linking agent is N,N-methylenebisacrylamide.

[0014] The crosslinker has two carbon-carbon double bonds, which can connect different polymer segments in a free radical polymerization reaction, thereby forming a stable polymer spatial network structure and significantly improving the water dispersibility of concrete.

[0015] Furthermore, the initiator is a combination of ammonium persulfate and an initiation auxiliary, and the initiation auxiliary is selected from one of ferrous sulfate, sodium hypophosphite and sodium peroxybisulfite.

[0016] The initiator can generate free radicals at a relatively low temperature through a redox reaction with ammonium persulfate, promoting the rapid progress of the self-polymerization reaction. The ferrous sulfate in the initiator must be used as soon as possible after the solution is prepared to prevent it from being oxidized and inactivated by exposure to air.

[0017] Furthermore, the usage amount of the initiation auxiliary agent is 30%-60% of the ammonium persulfate.

[0018] The amount and ratio of the initiator and the initiator have a great influence on the amount of free radicals generated. Generally, ammonium persulfate is excessive, and the amount of free radicals generated can be controlled by adjusting the amount of the initiator.

[0019] Furthermore, the silicate cement is 42.5 grade ordinary silicate cement, and the water content of the cement standard consistency is ≤26%.

[0020] Furthermore, the river sand fineness modulus is 2.7-3.0.

[0021] Furthermore, the crushed stone has a particle size range of 5-16 mm and an average particle size of 12 mm.

[0022] A method for preparing underwater anti-dispersion concrete based on monomer self-polymerization, the preparation method comprising the following steps:

[0023] 1) Pour gravel, river sand and cement into a mixer and mix them evenly to obtain dry powder;

[0024] 2) Add the polymerization monomer, cross-linking agent and ammonium persulfate to most of the water, stir evenly, pour into the dry powder, and mechanically stir to obtain concrete with good dispersion;

[0025] 3) Dissolve the initiator in the remaining water and add the initiator solution in stages. After each stage, wait for the polymerization reaction to stabilize and analyze the concrete performance until the performance meets the standard. If there is any remaining initiator solution after meeting the standard, stop adding it and add water to the specified water-cement ratio.

[0026] Furthermore, in step 3), the initiating auxiliary agent is added dropwise for 2 minutes at each stage, and the amount added is 10% of the total amount of the auxiliary agent solution.

[0027] The beneficial effects of adopting the technical solution of the present invention are:

[0028] 1) Traditional underwater concrete often suffers from poor water dispersion resistance, particularly in underwater environments, where it is prone to segregation or instability, resulting in insufficient strength and increased construction difficulty. This invention utilizes monomer autopolymerization to generate a high-molecular-weight polymer network, significantly improving the concrete's water dispersion resistance during the plastic phase. The formation of this polymer network effectively strengthens the bonding between cement particles, reduces water erosion of the concrete, and ensures the concrete's stability and durability in underwater environments.

[0029] 2) In the modification process of traditional underwater concrete, when using additives such as water reducers or tackifiers, performance problems often occur, resulting in the working performance of the concrete being affected. In the present invention, no water reducer is added. By precisely controlling the monomer self-polymerization reaction, specifically by controlling the amount of initiator and controlling the monomer self-polymerization reaction by dripping, the water dispersibility of the concrete in the plastic stage is significantly improved. At the same time, no polymerization reaction occurs and the high molecular polymer with shorter chain segments can produce a lubricating effect between the cement particles, which can effectively maintain the fluidity and workability of the concrete. In particular, the lubricating effect generated between the cement particles contributes to the easy workability of the concrete in the working stage, avoiding the defects of excessive adhesion or insufficient fluidity that may occur in traditional modification methods. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the invention in conjunction with the specific 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.

[0031] An underwater anti-dispersion concrete based on monomer self-polymerization, comprising the following components per cubic meter of concrete: (20-40) kg of polymerization monomer; (0.2-0.4) kg of cross-linking agent; (0.5-0.8) kg of initiator; (300-400) kg of Portland cement; (700-800) kg of river sand; (1100-1200) kg of crushed stone; and (160-200) kg of water.

[0032] The initiator is a combination of ammonium persulfate and an initiation aid, the initiation aid is one of ferric sulfite, sodium hypophosphite and sodium peroxybisulfite, and the amount of the initiation aid used is 30%-60% of the ammonium persulfate; the Portland cement is 42.5 grade ordinary Portland cement, and the water consumption of the cement standard consistency is ≤26%; the fineness modulus of the river sand is 2.7-3.0; the crushed stone particle size range is (5-16) mm, and the average particle size is 12 mm.

[0033] The underwater anti-dispersion concrete preparation method is as follows: crushed stone, river sand and cement are poured into a mixer and stirred to mix evenly to obtain a dry powder; polymerization monomer, cross-linking agent and ammonium persulfate are added to a large portion of water, stirred evenly, and then poured into the dry powder, and mechanically stirred for 2 minutes to obtain concrete with good dispersibility; an initiator is dissolved in the remaining water, and an initiator solution is added dropwise in stages, each stage lasting 2 minutes, with the addition amount being 10% of the solution; after each stage, the polymerization reaction is stabilized, and the working performance of the concrete is analyzed until the working performance meets the standard. After meeting the standard, if any initiator solution remains, no more initiator solution is added, and water is added to a specified water-cement ratio to obtain underwater anti-dispersion concrete with anti-water dispersion and good fluidity.

[0034] This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0035] Example 1

[0036] An underwater anti-dispersion concrete based on monomer self-polymerization includes the following components: 30 kg of polymerization monomer (acrylamide); 0.3 kg of cross-linking agent; 0.5 kg of ammonium persulfate; 0.2 kg of sodium bisulfite; 350 kg of Portland cement; 750 kg of river sand; 1150 kg of crushed stone; and 180 kg of water.

[0037] Example 2

[0038] An underwater anti-dispersion concrete based on monomer self-polymerization includes the following components: 30 kg of polymerization monomers (acrylic acid: acrylamide: acrylamide and 2-acrylamide-2-methylpropane sulfonic acid = 2:2:1); 0.3 kg of a cross-linking agent; 0.5 kg of ammonium persulfate; 0.2 kg of sodium bisulfite; 350 kg of Portland cement; 750 kg of river sand; 1150 kg of crushed stone; and 180 kg of water.

[0039] Example 3

[0040] An underwater anti-dispersion concrete based on monomer self-polymerization includes the following components: 30 kg of polymerization monomers (acrylic acid: acrylamide: acrylamide and 2-acrylamide-2-methylpropane sulfonic acid = 1:1:3); 0.3 kg of a cross-linking agent; 0.5 kg of ammonium persulfate; 0.2 kg of sodium bisulfite; 350 kg of Portland cement; 750 kg of river sand; 1150 kg of crushed stone; and 180 kg of water.

[0041] Example 4

[0042] An underwater anti-dispersion concrete based on monomer self-polymerization includes the following components: 30 kg of polymerization monomers (acrylic acid: acrylamide: acrylamide and 2-acrylamido-2-methylpropanesulfonic acid = 1:1:3); 0.3 kg of cross-linking agent; 0.5 kg of ammonium persulfate; 0.2 kg of sodium bisulfite; 350 kg of Portland cement; 750 kg of river sand; 1150 kg of crushed stone; and 180 kg of water. The initiator is added dropwise all at once.

[0043] Comparative Example 1

[0044] An underwater anti-dispersion concrete comprises the following components: 2 kg of hydroxypropyl methylcellulose ether, 2 kg of a polycarboxylic acid-based water reducer, 350 kg of Portland cement, 750 kg of river sand, 1150 kg of crushed stone, and 180 kg of water.

[0045] The slump and slump spread of underwater anti-concrete were tested in accordance with DL / T 5117-2021 "Test Procedure for Underwater Non-dispersible Concrete". 100mm×100mm×100mm specimens were prepared in water and air respectively. After curing for 28 days, the compressive strength was measured and the water-to-land strength ratio was calculated.

[0046] The following table shows the test results:

[0047]

[0048]

[0049] From the slump, expansion, and water-to-land strength ratio test results in the table, it can be seen that the working performance of the embodiments is better than that of the comparative examples, which can enable water-based anti-dispersion concrete to be better adaptively formed in water. At the same time, the water-resistance of the embodiments is better than that of the comparative examples. In addition, compared with the single dropwise addition of the initiating agent, the segmented dropwise addition can effectively regulate the molecular weight of the polymer generated by self-polymerization, thereby improving the flow properties of the concrete. The combined effect of the two improves the strength of the molded specimens in the embodiments after curing in water, that is, improves the water-to-land strength ratio.

[0050] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent claim scheme. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. An underwater anti-dispersion concrete based on monomer self-polymerization, characterized in that: The concrete includes the following components and contents by weight: 20-40 parts of polymerization monomer; Cross-linking agent 0.2-0.4 parts; 0.5-0.8 parts of initiator; 300-400 parts of Portland cement; 700-800 parts of river sand; 1100-1200 parts of crushed stone; 160-200 parts of water.

2. The underwater anti-dispersion concrete based on monomer self-polymerization according to claim 1, characterized in that: The polymerization monomer is one or more of acrylic acid, acrylamide and 2-acrylamide-2-methylpropane sulfonic acid.

3. The underwater anti-dispersion concrete based on monomer self-polymerization according to claim 1, characterized in that: The cross-linking agent is N,N-methylenebisacrylamide.

4. The underwater anti-dispersion concrete based on monomer self-polymerization according to claim 1, characterized in that: The initiator is a combination of ammonium persulfate and an initiation auxiliary agent, and the initiation auxiliary agent is selected from one of ferrous sulfate, sodium hypophosphite and sodium peroxybisulfite.

5. The underwater anti-dispersion concrete based on monomer self-polymerization according to claim 4, characterized in that: The usage amount of the initiation auxiliary agent is 30%-60% of the ammonium persulfate.

6. The underwater anti-dispersion concrete based on monomer self-polymerization according to claim 1, characterized in that: The silicate cement is 42.5 grade ordinary silicate cement, and the water consumption of the cement standard consistency is ≤26%.

7. The underwater anti-dispersion concrete based on monomer self-polymerization according to claim 1, characterized in that: The river sand fineness modulus is 2.7-3.

0.

8. The underwater anti-dispersion concrete based on monomer self-polymerization according to claim 1, characterized in that: The crushed stone has a particle size range of 5-16 mm and an average particle size of 12 mm.

9. The method for preparing underwater anti-dispersion concrete based on monomer self-polymerization according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: 1) Pour gravel, river sand and cement into a mixer and mix them evenly to obtain dry powder; 2) Add the polymerization monomer, cross-linking agent and ammonium persulfate to most of the water, stir evenly, pour into the dry powder, and mechanically stir to obtain concrete with good dispersion; 3) Dissolve the initiator in the remaining water and add the initiator solution in stages. After each stage, wait for the polymerization reaction to stabilize and analyze the concrete performance until the performance meets the standard. If there is any remaining initiator solution after meeting the standard, stop adding it and add water to the specified water-cement ratio.

10. The method for preparing underwater anti-dispersion concrete based on monomer self-polymerization according to claim 9, characterized in that: In step 3), the initiating auxiliary agent is added dropwise for 2 minutes at each stage, and the amount added is 10% of the total amount of the auxiliary agent solution.

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