Preparation and application of low-carbon concrete

Abstract

The invention relates to a cement-based building material, in particular to preparation and application of low-carbon concrete, and the low-carbon concrete is prepared by mixing polycarboxylic acid mother liquor, a KFDN-DT polycarboxylic acid water reducer additive solution and concrete; the polycarboxylic acid mother liquor comprises a base material, a dripping material a and a dripping material b, and the base material comprises 30%-40% of methyl allyl polyoxyethylene ether and 0.005%-0.015% of butyl acrylate; the dropping material a comprises 3%-4.5% of acrylic acid; the dropping material b comprises 0.005%-0.01% of a reducing agent and 0.1%-0.3% of a chain transfer agent; the KFDN-DT polycarboxylic acid water reducer auxiliary agent comprises 45% of a bleeding blocking agent and 10% of a water reducing agent. 5% of a dispersant; 8% of a powder mud blocking agent; 20% of a reinforcing agent; 15% of a slow release agent; and 7% of a viscosity reducer. The low-carbon concrete provided by the invention has excellent water-reducing, reinforcing and slow-release properties and the like, and the working performance and durability of the concrete can be remarkably improved.

Description

Technical Field

[0001] The invention relates to cement-based building materials, and in particular to the preparation and application of low-carbon concrete. Background Art

[0002] With the rapid development of the construction industry, the performance requirements for concrete are getting higher and higher. Traditional concrete admixtures have played an important role in improving the working performance and mechanical properties of concrete, but they have certain limitations in terms of environmental protection and sustainable development. For example, some admixtures may increase the carbon emissions of concrete (affecting the strength and durability of concrete), which is not in line with the current low-carbon and environmentally friendly development concept. Moreover, in the face of complex construction environments and special engineering needs, traditional admixtures are difficult to meet the comprehensive performance requirements of concrete in terms of collapse resistance, strength improvement, and water resistance. Super high-rise buildings, residential buildings, high-speed railways, and highways, as the largest building material, have also ushered in a production peak, while promoting the rapid development of high-performance concrete technology. Recently, the requirements of the engineering and material industries for concrete have not only required high strength, but also higher requirements for the durability and construction of concrete. It can be said that the gap between countries in concrete technology has shifted from the original cement, sand and gravel, and admixtures to the development level of water reducers. The core and soul of ultra-high performance concrete is concrete admixtures.

[0003] The concept of "low-carbon concrete" includes several aspects: 1. Durability of buildings; 2. Low-carbon requirements for concrete production; 3. Convenience of concrete during transportation and construction. In fact, without good concrete, there is no durability of buildings. Excessive cement and water consumption are the main factors for cracking of buildings. Good commercial concrete will not deactivate and harden in a short time, affecting construction. Good concrete: guaranteed strength, satisfactory construction and workability, no cracks.

[0004] CN103450411A discloses a method for preparing a high-slump-retaining polycarboxylic acid water-reducing agent. The method comprises the following steps: firstly, methoxy polyethylene glycol monomethyl ethers of different molecular weights are esterified with methacrylic acid and a mixed polymerization inhibitor, and then allyl alcohol is added for further esterification to obtain an esterified macromonomer MP containing a cross-linking monomer allyl methacrylate; then, MP, an unsaturated sulfonate, an acrylate unsaturated monomer and a chain transfer agent are polymerized in aqueous solution in a redox initiation system and at low temperature, and finally, liquid alkali is added for neutralization to obtain a polycarboxylic acid water-reducing agent of a certain concentration.

[0005] CN104177562A uses specific monomers A, B, polymer macromonomers C, D and E to prepare a slow-release polyester polycarboxylic acid water reducer with strong adaptability. However, the slump-retaining slow-release water reducer in the prior art has high raw material cost and complex process, and cannot simultaneously meet the construction requirements of low carbon, high water reduction and ultra-long time slump-retaining. The slump-retaining performance of cement-based materials after 2 hours cannot be guaranteed. Other types of water reducers need to be compounded during use, and a large number of experiments are required to study the compatibility of other types of water reducers.

[0006] CN116535131B discloses an application of an admixture additive for producing low-carbon commercial concrete. The patent adopts KFDN-DT polycarboxylate water-reducing agent additive solution to reduce cement and unit water consumption when producing concrete, maintain concrete construction and workability, and achieve concrete strength and durability guarantee. Under the premise of ensuring concrete construction and strength, the quality of concrete is improved, and good results are produced. Therefore, the present application develops a low-carbon concrete with better performance on the basis of it to meet the construction industry's demand for high-performance, environmentally friendly concrete. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the prior art, the present invention provides a preparation method and application of low-carbon concrete, which greatly reduces the amount of cement used while reducing the water consumption of concrete per cubic meter, thereby ensuring the design strength and later development of concrete.

[0008] A method for preparing low-carbon concrete comprises mixing a polycarboxylic acid mother solution, a KFDN-DT polycarboxylic acid water-reducing agent auxiliary solution and concrete;

[0009] The polycarboxylic acid mother liquor comprises a base material, a drop material a and a drop material b, wherein the base material comprises 30%-40% of methyl allyl polyoxyethylene ether, 0.005%-0.015% of butyl acrylate, 0.1%-1.2% of an initiator and 40%-62% of pure water; the drop material a comprises 3%-4.5% of acrylic acid and 3%-4.5% of pure water; the drop material b comprises 0.005%-0.01% of a reducing agent, 0.1%-0.3% of a chain transfer agent and 5%-10% of pure water;

[0010] The KFDN-DT polycarboxylate water-reducing agent auxiliary comprises the following raw materials in weight ratio: 45% of water seepage blocking agent; 5% of dispersant; 8% of powder mud blocking agent; 20% of reinforcing agent; 15% of slow-release agent; and 7% of viscosity reducer.

[0011] Preferably, the base material comprises 30% methyl allyl polyoxyethylene ether, 0.005% butyl acrylate, 0.1% initiator and the balance pure water; the drop material a comprises 3% acrylic acid and the balance pure water; the drop material b comprises 0.005% reducing agent, 0.1% chain transfer agent and the balance pure water.

[0012] Preferably, the base material comprises 35% of methyl allyl polyoxyethylene ether, 0.01% of butyl acrylate, 0.15% of initiator and the balance of pure water; the dropping material a comprises 4% of acrylic acid and the balance of pure water; the dropping material b comprises 0.008% of reducing agent, 0.2% of chain transfer agent and the balance of pure water.

[0013] Preferably, the base material comprises 40% of methyl allyl polyoxyethylene ether, 0.015% of butyl acrylate, 1.2% of initiator and the balance of pure water; the dropping material a comprises 4.5% of acrylic acid and the balance of pure water; the dropping material b comprises 0.01% of reducing agent, 0.3% of chain transfer agent and the balance of pure water.

[0014] The beneficial effects of the present invention are as follows:

[0015] 1. The low-carbon concrete of the present invention, through the combination of polycarboxylic acid mother liquor and polycarboxylic acid water-reducing agent auxiliary solution, can significantly reduce the amount of cement used and the water consumption per unit volume of concrete, effectively reducing the carbon emission of concrete and meeting the requirements of low-carbon environmental protection;

[0016] 2. Using the product of the present invention, concrete production plants can easily cope with situations that may cause unloading delays, such as hot weather, traffic jams, and queuing at construction sites;

[0017] 3. The present invention is simple and easy to use, ensuring that the quality of concrete remains unchanged from factory to unloading. The concrete exhibits excellent performance in various tests, with a slump retention value of 240 mm after 2 hours and a 28-day compressive strength greater than 44 MPa.

[0018] 4. It ensures the design requirements and durability of concrete, maintains the workability of concrete for 2 hours or longer, meets the construction and use requirements of different projects; effectively avoids cracks caused by cement hydration and poor workability (slump loss) of concrete;

[0019] 5. The present invention has no special requirements for concrete materials and can be used for recycled aggregate concrete, with wide applicability; it conforms to the national policies of "high-quality development" and "low-carbon emission reduction". Detailed implementation manners

[0020] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0021] Properties and uses of each raw material:

[0022] Methyl allyl polyoxyethylene ether: As an important macromonomer of polycarboxylate mother liquor, during the synthesis process, it provides long polyoxyethylene side chains for polycarboxylate molecules. These side chains stretch in the aqueous solution, capable of generating steric hindrance effects, making cement particles repel each other, thus effectively dispersing cement particles, preventing their aggregation, significantly improving the fluidity and workability of concrete, and playing a key role in dispersing and maintaining slump in concrete.

[0023] Butyl acrylate: Participates in the polymerization reaction, regulates the structure of polycarboxylate molecules, changes the balance of their hydrophilicity and hydrophobicity, helps enhance the adsorption between the polycarboxylate mother liquor and the surface of cement particles, thereby improving the water reduction effect and optimizing the work performance of concrete.

[0024] Initiator: Common ones such as aqueous persulfate initiators decompose to generate free radicals at a certain temperature, initiating the polymerization reaction. The free radicals attack monomer molecules such as methyl allyl polyoxyethylene ether and butyl acrylate, causing them to undergo chain polymerization reactions, thus forming polycarboxylate polymers with specific structures and properties.

[0025] Purified water: As the reaction medium, it provides a uniformly dispersed environment for each monomer and initiator, etc., ensuring the smooth progress of the polymerization reaction in a homogeneous system, and at the same time also affecting the concentration and performance of the final product.

[0026] Acrylic acid: Contains carboxyl groups. During the polymerization reaction, the carboxyl groups can complex with metal ions on the surface of cement particles, making the surface of cement particles carry negative charges, and dispersing cement particles through electrostatic repulsion, playing a role in water reduction and setting retardation. At the same time, copolymerizing with other monomers can adjust the structure of polycarboxylate molecules and enhance their adsorption and dispersion properties on cement particles.

[0027] Reducing agent: Such as sodium sulfite, etc., which synergistically acts with the initiator in the polymerization reaction, generates free radicals through redox reactions, accelerates the rate of the initiation polymerization reaction, and at the same time can control the molecular weight and molecular structure of the polymer, making the polycarboxylate mother liquor have appropriate properties.

[0028] Chain transfer agent: For example, 3-mercaptopropionic acid, which can transfer active free radicals from the growing chain during the polymerization reaction, thereby controlling the molecular weight of the polymer, avoiding poor product performance caused by excessive molecular weight, and ensuring the dispersion performance and stability of the polycarboxylate mother liquor.

[0029] Bleeding blocker: By interacting with the water and cement particles in concrete, it forms a network structure with a certain cohesion, preventing the migration and precipitation of water, thus effectively preventing the bleeding phenomenon of concrete from occurring and improving the uniformity and durability of concrete. Common ones are certain high molecular polymers, which can adsorb on the surface of cement particles and fill between cement particles, increasing the viscosity of the system and inhibiting the flow of water.

[0030] Dispersant: Its molecular structure contains hydrophilic and hydrophobic groups. The hydrophilic groups combine with the water molecules on the surface of cement particles, and the hydrophobic groups face the aqueous solution. This structure enables the dispersant to adsorb on the surface of cement particles, reduce the surface tension between cement particles, and disperse the agglomerated cement particles through electrostatic repulsion and steric hindrance effects, improving the fluidity of concrete and making it easier to mix, transport, and pour during construction.

[0031] Slurry blocker: It can chemically react or physically adsorb with the slurry components in concrete to form a stable complex, prevent the slurry from coating the cement particles and adsorbing the water reducer, reduce the negative impact of the slurry on the performance of concrete, improve the effective utilization rate of the water reducer, and ensure the strength and workability of concrete.

[0032] Strength enhancer: By undergoing a secondary reaction with the hydration products of cement, it generates more gel substances to fill the pores inside the concrete, improving the density and strength of the concrete. For example, some active mineral admixtures such as silica fume and metakaolin can react with the calcium hydroxide produced by cement hydration to generate cementitious substances and enhance the structural strength of the concrete.

[0033] Retarder: It slowly releases the active ingredients in concrete, extends the action time of the water reducer, maintains the fluidity and workability of concrete for a long time, and prevents the rapid loss of concrete slump. Generally, it is composed of some organic compounds with special structures, which gradually decompose in the alkaline environment of concrete to release the water-reducing components, thus achieving the slow-release effect.

[0034] Viscosity reducer: It reduces the viscosity of the concrete mixture and improves its rheological properties. It destroys the flocculent structure inside the concrete, reduces the friction between cement particles, and reduces the water consumption while ensuring the workability of the concrete, improving the construction performance and economy of the concrete.

[0035] Example 1:

[0036] A certain amount of concrete;

[0037] Weigh the base materials: 30 kg of methyl allyl polyoxyethylene ether, 0.005 kg of butyl acrylate, 0.1 kg of initiator, and make up the balance to 100 kg with pure water; Drop feed a: 3 kg of acrylic acid, and make up the balance to 100 kg with pure water; Drop feed b: 0.005 kg of reducing agent, 0.1 kg of chain transfer agent, and make up the balance to 100 kg with pure water. The KFDN-DT polycarboxylate water reducer additive is in a weight ratio of: 45 kg of bleeding blocker; 5 kg of dispersant; 8 kg of slurry blocker; 20 kg of strength enhancer; 15 kg of retarder; 7 kg of viscosity reducer.

[0038] Mix the above-mentioned weighed raw materials according to the synthesis process, that is, mix them evenly to make low-carbon concrete.

[0039] Example 2:

[0040] Several concretes;

[0041] Base material: 35 kg of methylallyl polyoxyethylene ether, 0.01 kg of butyl acrylate, 0.15 kg of initiator, and the balance is made up to 100 kg with pure water; Dropwise addition material a: 4 kg of acrylic acid, and the balance is made up to 100 kg with pure water; Dropwise addition material b: 0.008 kg of reducing agent, 0.2 kg of chain transfer agent, and the balance is made up to 100 kg with pure water. The weight ratios of the raw materials of the KFDN-DT polycarboxylate superplasticizer assistant remain unchanged.

[0042] Example 3:

[0043] Several concretes;

[0044] Base material: 40 kg of methylallyl polyoxyethylene ether, 0.015 kg of butyl acrylate, 1.2 kg of initiator, and the balance is made up to 100 kg with pure water; Dropwise addition material a: 4.5 kg of acrylic acid, and the balance is made up to 100 kg with pure water; Dropwise addition material b: 0.01 kg of reducing agent, 0.3 kg of chain transfer agent, and the balance is made up to 100 kg with pure water. The raw material ratios of the KFDN-DT polycarboxylate superplasticizer assistant are the same as before.

[0045] The following is the trial mix of "low-carbon" and "high-quality" C30 concrete:

[0046] Table 1

[0047]

[0048] As can be seen from the above table, the low-carbon concrete prepared by the present invention has excellent performance in all aspects. The slump retention value after 2 hours is 240 mm, and the compressive strength after 28 days is greater than 44 MPa.

[0049] The following is the mix ratio of low-cement and recycled aggregate C30 concrete:

[0050] Table 2

[0051]

[0052] As can be seen from the above table, the present invention can reduce cement and unit water consumption during the production of concrete, maintain the workability of concrete during construction, and ensure the strength and durability of concrete.

[0053] The low-carbon concrete provided by the present invention has excellent water-reducing, strength-enhancing, slow-release and other properties, and can significantly improve the workability and durability of concrete. The preparation method is simple, easy to industrialize, and has broad application prospects.

[0054] The above are only the preferred embodiments of the present invention patent and are not intended to limit the present invention patent. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention patent shall be included within the protection scope of the present invention patent.

Claims

1. A method for preparing low-carbon concrete, characterized in that: It includes mixing polycarboxylic acid mother solution, KFDN-DT polycarboxylic acid water-reducing agent auxiliary solution with concrete; The polycarboxylic acid mother liquor comprises a base material, a drop material a and a drop material b, wherein the base material comprises 30%-40% of methyl allyl polyoxyethylene ether, 0.005%-0.015% of butyl acrylate, 0.1%-1.2% of an initiator and 40%-62% of pure water; the drop material a comprises 3%-4.5% of acrylic acid and 3%-4.5% of pure water; the drop material b comprises 0.005%-0.01% of a reducing agent, 0.1%-0.3% of a chain transfer agent and 5%-10% of pure water; The KFDN-DT polycarboxylate water-reducing agent auxiliary comprises the following raw materials in weight ratio: 45% of water seepage blocking agent; 5% of dispersant; 8% of powder mud blocking agent; 20% of reinforcing agent; 15% of slow-release agent; and 7% of viscosity reducer.

2. The preparation of a low-carbon concrete according to claim 1, characterized in that: The base material comprises 30% methyl allyl polyoxyethylene ether, 0.005% butyl acrylate, 0.1% initiator and the balance of pure water; the drop material a comprises 3% acrylic acid and the balance of pure water; the drop material b comprises 0.005% reducing agent, 0.1% chain transfer agent and the balance of pure water.

3. The preparation of a low-carbon concrete according to claim 1, characterized in that: The base material comprises 35% methyl allyl polyoxyethylene ether, 0.01% butyl acrylate, 0.15% initiator and the balance of pure water; the drop material a comprises 4% acrylic acid and the balance of pure water; the drop material b comprises 0.008% reducing agent, 0.2% chain transfer agent and the balance of pure water.

4. The preparation of a low-carbon concrete according to claim 1, characterized in that: The base material comprises 40% methyl allyl polyoxyethylene ether, 0.015% butyl acrylate, 1.2% initiator and the balance of pure water; the drop material a comprises 4.5% acrylic acid and the balance of pure water; the drop material b comprises 0.01% reducing agent, 0.3% chain transfer agent and the balance of pure water.

5. The preparation of a low-carbon concrete according to claim 1, characterized in that: The synthesis process of the concrete is as follows: raw materials are weighed in proportion and mixed evenly to prepare low-carbon concrete.

6. Application of the preparation of the low-carbon concrete according to any one of claims 1 to 5 in the field of building construction.

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