Efficient concrete early strength agent compounded with aluminate coupling agent

Abstract

The invention discloses an efficient concrete early strength agent compounded with an aluminate coupling agent, and relates to the technical field of building materials. The early strength agent provided by the invention comprises the following components in percentage by mass: 5-20% of a calcium source, 3-10% of a silicon source, 0.5-1% of a water reducing agent, 1-2% of a reinforcing agent, 3-5% of a modifier, 1-5% of an aluminate coupling agent, 0.03-0.08% of a pH regulator and the balance of water. The prepared early strength agent has the characteristics of high early strength and low cost.

Description

Technical Field

[0001] This invention relates to the field of building materials design, and is particularly applicable to a method for preparing a high-efficiency concrete early-strength agent with a compound aluminate coupling agent. Background Technology

[0002] With the continuous improvement of industrialization in China's construction industry, the concrete products and prefabricated building industries have developed rapidly, further increasing the requirements for the initial strength of concrete. Traditional precast concrete production typically employs steam curing to improve the initial strength of concrete, thereby shortening demolding time and improving formwork replacement efficiency. However, steam curing consumes a large amount of heat energy, reduces concrete durability, increases costs, and causes environmental problems by emitting greenhouse gases such as carbon dioxide, sulfur dioxide, and nitrogen oxides.

[0003] Concrete accelerator is an admixture used to accelerate the hydration reaction of cement and improve the initial strength of concrete. It can speed up the construction process, reduce the running time of molds, and save a lot of manpower and material resources. Therefore, accelerator has been rapidly developed and widely used in concrete construction.

[0004] Chinese patent CN107337372A discloses an early-strength agent based on composite nanomaterials. The technical solution involves first uniformly mixing nano-calcium carbonate and a dispersant to obtain a suspension, and then mixing the uniformly mixed suspension with soluble calcium salts and soluble silicates to successfully prepare the early-strength agent. This early-strength agent achieves uniform particle dispersion by introducing a polymeric dispersant, and then utilizes the complementary advantages of two different nanomaterials, resulting in a compressive strength increase of over 100% in the first 10 hours. However, the high dosage of dispersant used in its preparation process leads to high costs.

[0005] Chinese patent CN201410614530.5 discloses "a nano-suspension concrete early-strength agent that can be stably dispersed in an aqueous solution." The technical solution is roughly as follows: a thixotropic solution is obtained by uniformly mixing and stirring a soluble aqueous salt and a soluble fluorosilicone salt aqueous solution; then, a polymer and a soluble silicate are added dropwise and mixed to form a nano-calcium silicate suspension. The prepared thixotropic solution and the nano-calcium silicate suspension are then uniformly mixed to obtain the nano-suspension concrete early-strength agent. Although the prepared early-strength agent shows a significant effect on improving concrete strength before 1 day, the improvement effect is not obvious after 1 day. Summary of the Invention

[0006] The purpose of this invention is to address the problems of insufficient early strength and excessive cost of some existing early strength agents by providing a highly efficient concrete early strength agent with significant early-stage effects and a method for its preparation.

[0007] The early strength agent provided by this invention comprises the following components: 5-20% calcium source, 3-10% silicon source, 0.5-1% water-reducing agent, 1-2% reinforcing agent, 3-5% modifier, 1-5% aluminate coupling agent, 0.03-0.08% pH adjuster, and the balance being water.

[0008] The main innovation of the early-strength agent formulation of this invention lies in utilizing the bifunctional groups of the metal ester coupling agent (which are both organic and inorganic) to reduce particle size. During the preparation process, the competitive adsorption of the metal coupling agent and the polycarboxylate superplasticizer significantly reduces the size of the CSH / PCE composite particles. The resulting early-strength agent contains hydrated calcium silicate (CSH) seed crystals, which can serve as nucleation sites for cement hydration, lowering the energy barrier for nucleation and thus accelerating the cement hydration rate and improving the early-stage hydration strength of the cement.

[0009] In this invention, the water-reducing agent is a melamine-formaldehyde condensate or a polycarboxylate water-reducing agent.

[0010] Furthermore, the structural formula of the aluminate coupling agent is (C3H7O). x ·Al(OCOR) m (OCOR2) n (OAB) y This includes one or more of DL-411, DL-411DF, and DL-411D.

[0011] Furthermore, one or more of diethanol monoisopropanolamine or calcium lignosulfonate.

[0012] Furthermore, the modifier is one or more of potassium sodium tartrate or sodium persulfonate.

[0013] Furthermore, the calcium source is one or more combinations of calcium nitrate, calcium chloride, calcium nitrate nonahydrate, and calcium formate.

[0014] Furthermore, the silicon source is one or more combinations of sodium metasilicate, magnesium silicate, sodium silicate, and aluminum silicate.

[0015] The present invention also includes the application of a high-efficiency concrete early strength agent with a compound aluminate coupling agent, wherein the early strength agent is prepared by the above method and is used as an admixture of concrete, with a dosage of 5-10% of the concrete.

[0016] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are: the metal ester coupling agent containing bifunctional groups is beneficial to prevent particle agglomeration; the early strength agent obtained contains CHS seed crystals, which can serve as nucleation points for cement hydration, reduce the energy barrier for nucleation, thereby accelerating the cement hydration rate and improving the early hydration strength of cement. Detailed Implementation Plan

[0017] To more clearly and thoroughly illustrate the purpose, technical solution, and advantages of this invention, the following detailed description is provided in conjunction with embodiments. The specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0018] Example 1

[0019] A high-efficiency concrete early-strength agent with a compound aluminate coupling agent is prepared by the following steps:

[0020] S1. Weigh 72 g of water and 8 g of melamine-formaldehyde condensate water-reducing agent, mix them thoroughly to obtain solution A;

[0021] S2. Weigh 2.3 g of diethanol monoisopropanolamine and 3.9 g of potassium sodium tartrate, mix thoroughly to obtain solution B;

[0022] S3. Mix solution B and solution A to obtain solution C;

[0023] S4. Based on a calcium-silicon molar ratio of 0.05-0.05, weigh 6.6 g of calcium nitrate and 15 mL of water to form a calcium nitrate solution. Weigh 12.8 g of sodium metasilicate and 60 mL of water to form a sodium metasilicate solution. Then, add the sodium metasilicate solution to solution C at a dropping rate of 0.6 mL / min and 0.8 mL / min. The stirring rate of solution C is 400 r / min. After the addition is complete, add an appropriate amount of 3 mol / L sodium hydroxide to adjust the pH to 12.5. After stirring continuously for 3 h, an early strength agent with a solid content of 22.5% is obtained.

[0024] Example 2

[0025] A high-efficiency concrete early-strength agent with a compound aluminate coupling agent is prepared by the following steps:

[0026] S1. Weigh 72 g of water and 8 g of melamine-formaldehyde condensate water-reducing agent, mix them thoroughly to obtain solution A;

[0027] S2. Weigh 2.3 g of diethanol monoisopropanolamine and 3.9 g of potassium sodium tartrate, mix thoroughly to obtain solution B;

[0028] S3. Mix solution B and solution A to obtain solution C;

[0029] S4. Based on a calcium-silicon molar ratio of 0.05-0.05, weigh 6.6 g of calcium nitrate and 15 mL of water to form a calcium nitrate solution. Weigh 12.8 g of sodium metasilicate and 60 mL of water to form a sodium metasilicate solution. Then, add the sodium metasilicate solution to solution C at a dropping rate of 0.6 mL / min and 0.8 mL / min. The stirring rate of solution C is 400 r / min. After the addition is complete, add an appropriate amount of 3 mol / L sodium hydroxide to adjust the pH to 12.5. After stirring for 2 h, add 3 g of aluminate coupling agent and continue stirring for 3 h to obtain an early strength agent with a solid content of 22.5%.

[0030] Example 3

[0031] A high-efficiency concrete early-strength agent with a compound aluminate coupling agent is prepared by the following steps:

[0032] S1. Weigh 72 g of water and 10 g of melamine-formaldehyde condensate water-reducing agent, mix them thoroughly to obtain solution A;

[0033] S2. Weigh 2.5 g of diethanol monoisopropanolamine and 4.0 g of potassium sodium tartrate, mix them thoroughly to obtain solution B;

[0034] S3. Mix solution B and solution A to obtain solution C;

[0035] S4. Based on a calcium-silicon molar ratio of 0.05-0.05, weigh 6.6 g of calcium nitrate and 15 mL of water to form a calcium nitrite solution. Weigh 13 g of sodium metasilicate and mix it with 60 mL of water to form a sodium metasilicate solution. Then, add the solution to solution C at a dropping rate of 0.55 mL / min and 0.75 mL / min. The stirring rate of solution C is 400 r / min. After the addition is complete, add an appropriate amount of 3 mol / L sodium hydroxide to adjust the pH to 12.5. After stirring for 2 h, add 5 g of aluminate coupling agent and continue stirring for 3 h to obtain an early strength agent with a solid content of 25%.

[0036] Comparison of experimental data results

[0037] To further verify the active effect of the self-made early-strength agent on concrete and to provide practical production guidance, concrete compatibility experiments were conducted on the early-strength agents prepared under the above-mentioned different conditions. The relevant test methods for concrete physical properties were based on GB / T17671-2021, with the experimental conditions being: curing at 20 ℃ and humidity ≥90% for 3 days. The experimental mix proportions are shown in Table 1, and the relevant concrete performance tests are shown in Table 2.

[0038] Table 1 Concrete Mix Proportion Table (Unit: kg / m³) 3 )

[0039]

[0040] Table 2. Effects of Accelerating Agents on Concrete Performance

[0041]

[0042] As can be seen from Tables 1 and 2, compared with the early-strength agent without the addition of aluminate coupling agent, the use of aluminate coupling agent improved the performance of the early-strength agent. The 1-day compressive strength increased by 21%, and the 3-day compressive strength increased by up to 10%. Adding the early-strength agents prepared in Examples 1 and 2 to concrete does not affect the workability of concrete, and improves the early strength of concrete. The 1-day compressive strength increased by up to 30%, and the 3-day compressive strength increased by up to 50%. It also has a certain promoting effect on the later stage and meets the strength requirements of concrete.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-efficiency concrete early-strength agent with a compound aluminate coupling agent, characterized in that, The early strength agent provided by this invention, by mass percentage, comprises the following components: 5-20% calcium source, 3-10% silicon source, 0.5-1% water-reducing agent, 1-2% reinforcing agent, 3-5% modifier, 1-5% aluminate coupling agent, 0.03-0.08% pH adjuster, with the balance being water.

2. The high-efficiency concrete early-strength agent material with compound aluminate coupling agent as described in claim 1, characterized in that, The water-reducing agent mentioned therein is one or more of melamine-formaldehyde condensate or polycarboxylate superplasticizer (PCE).

3. The high-efficiency concrete early-strength agent with a compound aluminate coupling agent as described in claim 1, characterized in that, The structural formula of the aluminate coupling agent is (C3H7O). x ·Al(OCOR) m (OCOR2) n (OAB) y This includes one or more of DL-411, DL-411DF, and DL-411D.

4. The high-efficiency concrete early-strength agent with a compound aluminate coupling agent as described in claim 1, characterized in that, The reinforcing agent is one or more of diethanol monoisopropanolamine or calcium lignosulfonate.

5. The high-efficiency concrete early-strength agent with a compound aluminate coupling agent as described in claim 1, characterized in that, The modifier is one or more of potassium sodium tartrate or sodium persulfonate.

6. The high-efficiency concrete early-strength agent with a compound aluminate coupling agent as described in claim 1, characterized in that, The calcium source mentioned therein is one or more combinations of calcium nitrate, calcium chloride, calcium nitrate nonahydrate, and calcium formate.

7. The high-efficiency concrete early-strength agent material with compound aluminate coupling agent as described in claim 1, characterized in that, The silicon source is one or more of sodium metasilicate, magnesium silicate, sodium silicate, and aluminum silicate.

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