A Janus structural concrete reinforcing agent and its preparation method and application

Abstract

The present invention provides a Janus structural concrete reinforcing agent and its preparation method and application. The present invention first generates a nano-silicon dioxide polymer composite material (SiO2-R) suspension by a condensation reaction between an organic polymer and a silicon source. Secondly, the SiO2-R suspension is complexed with metal particles to create a nano-crystal core C-S-H growth environment, and the size and performance of the crystal core are controlled by the polymer. The early strength and late strength of the concrete are enhanced by the nano-crystal core effect and the small size effect in the concrete. In addition, there is a hydrophilic polymer material on the surface of the nanoparticles, which migrates and diffuses rapidly in the concrete system and has a promoting effect on strength improvement. The present invention uses Fe 3+ The organic polymers are complexed to form an aqueous gel in which C‑S‑H is generated. The gel controls the size and properties of C‑S‑H, thereby synthesizing a Janus structured nanocomposite material with excellent performance.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete admixtures, and particularly relates to a Janus structural concrete reinforcing agent and a preparation method and application thereof. Background Art

[0002] With advancements in concrete technology, the requirements for concrete strength in building structures continue to rise, and this requirement is gradually extending to concrete admixtures. Currently, with the increasing demand for high-strength concrete in various projects such as railways, highways, and subways, higher requirements are being placed on the early strength of concrete to accelerate construction progress.

[0003] However, some common methods for strengthening concrete at an early stage can lead to reduced strength and even shrinkage in the later stages, thus affecting its durability. Therefore, the research and development of materials suitable for high-strength concrete that can enhance both early and late strength is crucial.

[0004] Common methods for enhancing the early strength of concrete include adding inorganic early-strength accelerators, applying ultrafine powders, and employing inorganic salt activators. However, the use of inorganic salts can negatively impact the concrete's later strength, while powders can be difficult to disperse evenly during application, thus reducing the early-strength effect. Furthermore, even when synthesizing polycarboxylate-based water-reducing agents with early-strength properties, or mixing conventional polycarboxylate-based water-reducing agents with early-strength accelerators, the early-strength effect achieved is often suboptimal.

[0005] Therefore, it is crucial to explore an admixture that can effectively enhance the strength of concrete. Summary of the Invention

[0006] The present invention provides a Janus structural concrete reinforcing agent and a preparation method thereof. A nano-silica polymer composite material (SiO2-R) suspension is generated by a condensation reaction between an organic polymer and a silicon source. The SiO2-R suspension is then complexed with metal particles to create a growth environment for nano-crystalline cores (CSH). The size and performance of the cores are controlled by the polymer.

[0007] Another object of the present invention is to provide an application of a Janus structural concrete reinforcing agent for concrete.

[0008] The specific technical solutions of the present invention are as follows:

[0009] A method for preparing a Janus structural concrete reinforcing agent comprises the following steps:

[0010] 1) Synthesis of nano-silica polymer composite material (SiO2-R) suspension;

[0011] 2) mixing a nano-silica polymer composite material (SiO2-R) suspension with water, a complexing agent and an alkali to form a base material;

[0012] 3) Mix the organic component R, silicon source and water to form material A; and mix the calcium source and water to form material B;

[0013] 4) Add material A and material B dropwise into the base material. After the addition is complete, keep warm and adjust the pH value to 9-12.

[0014] Step 1) specifically comprises: mixing an organic component R, a silicon source and water, reacting and aging to obtain a nano-silica polymer composite material (SiO2-R) suspension;

[0015] In step 1), the mass ratio of water, organic component R and silicon source is 200:10-100:10-50; preferably 200:50:20;

[0016] In step 1), the organic component R is selected from one or more of tannic acid, gallic acid, chlorogenic acid, and propyl gallate;

[0017] In step 1), the silicon source is selected from one or more of sodium metasilicate pentahydrate, sodium silicate, tetraethyl silicate, and tetramethyl silicate;

[0018] In step 1), the reaction is carried out at a water bath temperature of 30-50°C and stirred for 1-5 hours; preferably at 45°C and stirred for 4 hours;

[0019] In step 1), the aging refers to aging at a water bath temperature of 10-20° C. for 1-10 h; preferably aging at 15° C. for 5 h.

[0020] Nano-silica polymer composites can be represented by SiO2-R. In the structural formula, R represents the organic moiety, typically composed of one or more of tannic acid, gallic acid, chlorogenic acid, and propyl gallate. The silicon source in the SiO2 structure comes from one or more of sodium metasilicate pentahydrate, sodium silicate, tetraethyl silicate, and tetramethyl silicate. The hydroxyl groups on the R component promote the condensation reaction of the silicon source, forming the nano-silica polymer composite SiO2-R.

[0021] In step 2), the mass ratio of the nano-silica polymer composite material (SiO2-R) suspension, water, complexing agent and alkali is: 50-200:240:2-10:1-10; preferably, the mass ratio of the nano-silica polymer composite material (SiO2-R) suspension, water, complexing agent and alkali is: 200:240:5:5;

[0022] Preferably, in step 2), the nano-silica polymer composite material (SiO2-R) suspension and water are mixed in a water bath at a temperature of 10-45°C, and then a complexing agent is added, and then a base is added after 5-10 minutes;

[0023] In step 2), the complexing agent is ferrous sulfate;

[0024] In step 2), the base is a 30% mass concentration NaOH aqueous solution;

[0025] In step 3), in material A, the mass ratio of the organic component R, the silicon source and water is 1-10:5-30:85; preferably, the mass ratio of the organic component R, the silicon source and water is 3:10:85;

[0026] The organic component R is selected from one or more of tannic acid, gallic acid, chlorogenic acid, and propyl gallate;

[0027] The silicon source is selected from one or more of sodium metasilicate pentahydrate, sodium silicate, tetraethyl silicate, and tetramethyl silicate;

[0028] The organic component R and silicon source in the A material are selected from the same raw materials as the organic component R and silicon source in the base material.

[0029] In step 3), in material B, the mass ratio of the calcium source to water is: 15-25:85; preferably, the mass ratio of the calcium source to water is: 15:85;

[0030] In step 4), material A and material B were added dropwise at the same time, material A was added dropwise for 180 min, and material B was added dropwise for 190 min;

[0031] In step 4), after the addition of materials A and B is completed, the mixture is kept warm for 3 hours, and the pH value of the solution is adjusted to 9-12, preferably 9.5; the addition temperature is 15-25° C., and after the addition is completed, the mixture is kept warm without additional heating.

[0032] In step 4), after adjusting the pH value of the solution to 9-12, water is added to obtain a product that meets the solid content requirements.

[0033] The present invention provides a Janus structural concrete reinforcing agent, which is prepared by the above method. The prepared Janus structural concrete reinforcing agent is Fe-(SiO2-R) x (CSHR) y Indicates that R in the structural formula is an organic part, and the R part comes from one or more of tannic acid, gallic acid, chlorogenic acid, and propyl gallate; the SiO2 silicon source in the structural formula comes from one or more of sodium metasilicate pentahydrate, sodium silicate, tetraethyl silicate, and tetramethyl silicate; X represents 1-10, and Y represents 1-10.

[0034] The invention provides an application of a Janus structural concrete reinforcing agent for concrete.

[0035] Compared with the prior art, the present invention is different from other organic, inorganic or compound reinforcing agents and provides a Janus structure concrete reinforcing agent. The Janus structure concrete reinforcing agent is a composite product of two nanoparticles, and its main molecular structure is Fe-(SiO2-R) x (CSHR) y The concrete reinforcing agent was synthesized through a two-step process. First, a nano-silica polymer composite material (SiO2-R) suspension was generated by a condensation reaction between an organic polymer and a silicon source. Second, the SiO2-R suspension was complexed with metal particles to create an environment for the growth of nano-crystal cores (CSH). The size and properties of the cores were controlled by the polymer, resulting in the synthesis of a nano-concrete reinforcing agent Fe-(SiO2-R) with a Janus structure. x (CSHR) y . In concrete, the early strength and late strength of concrete are enhanced through the nano-crystal nucleation effect and small size effect. Different from the nano-particle compounding technology, the nano-structured reinforcing agent has the consistency of concrete strength enhancement, which makes the concrete strength distribution uniform and is beneficial to improving the durability of concrete. In addition, there is a hydrophilic polymer material on the surface of the nanoparticles, which migrates and diffuses quickly in the concrete system and has a promoting effect on strength improvement. The present invention uses Fe 3+ The organic polymers are complexed to form an aqueous gel in which CSH is generated. The gel controls the size and properties of CSH, thereby synthesizing a Janus structure nanocomposite material with excellent performance. DETAILED DESCRIPTION

[0036] The present invention provides a method for preparing a Janus structural concrete reinforcing agent, comprising the following steps:

[0037] 1) Synthesis of nano-silica polymer composite material (SiO2-R) suspension:

[0038] Measure 200mL of deionized water into a 500mL beaker, weigh 10-100g of organic component R and 10-50g of silicon source, then add them to the beaker and mix. Ultrasonicate for 10 minutes to evenly disperse them in the beaker. Place the beaker on a magnetic stirrer in a water bath at 30-50°C and stir for 1-5 hours. After stirring, place the beaker in a water bath at 10-20°C and age for 1-10 hours. The resulting solution is a suspension of nanosilica polymer composite material (SiO2-R).

[0039] 2) Janus structure nanocomposite Fe-(SiO2-R) x(CSHR) y Synthesis of:

[0040] 2-1) Primer: Add 50-200 g of a nano-silica polymer composite material (SiO2-R) suspension and 240 g of water to a 1 L four-necked glass bottle. Adjust the water bath temperature to 10-45°C to uniformly disperse the suspension in the solution. After the suspension is completely dispersed, add 2-10 g of ferrous sulfate and 1-10 g of a 30% aqueous NaOH solution to the four-necked bottle in sequence, leaving 5-10 minutes between additions.

[0041] 2-2) Prepare material A: organic component R1-10g, silicon source 5-30g, deionized water 85g; prepare material B: calcium source 15-25g, deionized water 85g;

[0042] 2-3) Start adding the prepared materials A and B dropwise; add material A dropwise for 180 minutes and material B dropwise for 190 minutes;

[0043] 2-4) After the addition of materials A and B is completed, the temperature is kept at room temperature for 3 hours, the pH value of the solution is adjusted to 9-12, and 305-516 g of water is added to terminate the reaction.

[0044] There are several preferred embodiments below, which are as follows:

[0045] Example 1

[0046] A method for preparing a Janus structural concrete reinforcing agent comprises the following steps:

[0047] 1) Synthesis of nano-silica polymer composite material (SiO2-R) suspension:

[0048] Measure 200mL of deionized water into a 500mL beaker, weigh 50g of tannic acid and 20g of sodium metasilicate pentahydrate, add them to the beaker, mix, and sonicate for 10 minutes to evenly disperse them in the beaker. Place the beaker on a magnetic stirrer in a 45°C water bath and stir for 4 hours. After stirring, place the beaker in a 15°C water bath and age for 5 hours. The resulting solution is a nanosilica polymer composite material (SiO2-R) suspension.

[0049] 2) Janus structure nanocomposite Fe-(SiO2-R) x (CSHR) y Synthesis of:

[0050] 2-1) Primer: Add 200 g of a nano-silica polymer composite material (SiO2-R) suspension and 240 g of water to a 1 L four-necked glass bottle. Adjust the water bath temperature to 25°C to uniformly disperse the suspension. After the suspension is completely dispersed, add 5 g of ferrous sulfate and 5 g of a 30% NaOH solution to the four-necked bottle in sequence, with a 10-minute interval between additions.

[0051] 2-2) Prepare Material A: 3g tannic acid, 10g sodium metasilicate pentahydrate, 85g deionized water; Prepare Material B: 15g calcium source, 85g deionized water;

[0052] 2-3) Start adding the prepared materials A and B dropwise; add material A dropwise for 180 minutes and material B dropwise for 190 minutes;

[0053] 2-4) After the addition of materials A and B was completed, the mixture was kept warm for 3 hours, the pH of the solution was adjusted to 9.5, and 405 g of water was added to terminate the reaction.

[0054] Example 2

[0055] A method for preparing a Janus structural concrete reinforcing agent comprises the following steps:

[0056] 1) Synthesis of nano-silica polymer composite material (SiO2-R) suspension:

[0057] Measure 200mL of deionized water into a 500mL beaker, weigh 20g of gallic acid and 40g of tetraethyl silicate, add them to the beaker, mix, and sonicate for 10 minutes to evenly disperse them in the beaker. Place the beaker on a magnetic stirrer in a 40°C water bath and stir for 5 hours. After stirring, place the beaker in a 10°C water bath and age for 6 hours. The resulting solution is a nanosilica polymer composite material (SiO2-R) suspension.

[0058] 2) Janus structure nanocomposite Fe-(SiO2-R) x (CSHR) y Synthesis of:

[0059] 2-1) Primer: Add 100 g of a nano-silica polymer composite material (SiO2-R) suspension and 240 g of water to a 1 L four-necked glass bottle. Adjust the water bath temperature to 35°C to uniformly disperse the suspension. After the suspension is completely dispersed, add 5 g of ferrous sulfate and 5 g of a 30% NaOH solution to the four-necked bottle in sequence, with a 10-minute interval between additions.

[0060] 2-2) Prepare Material A: 6g gallic acid, 15g tetraethyl silicate, 85g deionized water; Prepare Material B: 20g calcium source, 85g deionized water;

[0061] 2-3) Start adding the prepared materials A and B dropwise; add material A dropwise for 180 minutes and material B dropwise for 190 minutes;

[0062] 2-4) After the addition of materials A and B was completed, the mixture was kept warm for 3 hours, the pH of the solution was adjusted to 10, and 400 g of water was added to terminate the reaction.

[0063] Example 3

[0064] A method for preparing a Janus structural concrete reinforcing agent comprises the following steps:

[0065] 1) Synthesis of nano-silica polymer composite material (SiO2-R) suspension:

[0066] Measure 200mL of deionized water into a 500mL beaker, weigh 60g of propyl gallate and 30g of tetramethyl silicate, then add them to the beaker and mix. Ultrasonicate for 10 minutes to evenly disperse them in the beaker. Place the beaker on a magnetic stirrer in a water bath at 40°C and stir for 5 hours. After stirring, place the beaker in a water bath at 20°C and age for 6 hours. The resulting solution is a suspension of nanosilica polymer composite material (SiO2-R).

[0067] 2) Janus structure nanocomposite Fe-(SiO2-R) x (CSHR) y Synthesis of:

[0068] 2-1) Primer: Add 200 g of a nano-silica polymer composite material (SiO2-R) suspension and 240 g of water to a 1 L four-necked glass bottle. Adjust the water bath temperature to 25°C to uniformly disperse the suspension. After the suspension is completely dispersed, add 6 g of ferrous sulfate and 6 g of a 30% aqueous solution of NaOH to the four-necked bottle in sequence, with a 10-minute interval between additions.

[0069] 2-2) Prepare Material A: 7g propyl gallate, 22g tetramethyl silicate, 85g deionized water; Prepare Material B: 25g calcium source, 85g deionized water;

[0070] 2-3) Start adding the prepared materials A and B dropwise; add material A dropwise for 180 minutes and material B dropwise for 190 minutes;

[0071] 2-4) After the addition of materials A and B was completed, the mixture was kept warm for 3 hours, the pH of the solution was adjusted to 10, and 500 g of water was added to terminate the reaction.

[0072] The Janus structural concrete reinforcing agent prepared in Example 1 above was applied to concrete at addition levels of 0.03%, 0.06%, and 0.09%, respectively. Concrete strength was tested in accordance with GB 8076-2008, and the compressive strength of the tested concrete and the reference concrete was tested and calculated in accordance with GB / T 50081. During specimen preparation, the specimens were vibrated on a vibration table for 15-20 seconds. The specimens were pre-cured at a temperature of (20±3)°C. The composition of the concrete is shown in Table 1. The test results are shown in Table 2. For comparison, the test performance results of the concrete without the admixture are shown in Table 1.

[0073] Table 1 15L-C50 concrete mix ratio

[0074]

[0075] Table 2 Concrete compressive strength

[0076]

[0077] The invention provides a Janus structure concrete reinforcing agent for use in concrete to enhance the early strength and late strength of the concrete.

Claims

1. A method for preparing a Janus structural concrete reinforcing agent, characterized in that: The preparation method comprises the following steps: 1) Synthesize nano-silica polymer composite suspension, where the nano-silica polymer composite is represented by SiO2-R; 2) Mixing the nano-silica polymer composite suspension with water, a complexing agent, and an alkali to form a base material; 3) Mix the organic component R, silicon source and water to form material A; mix the calcium source and water to form material B; 4) Add material A and material B to the base material dropwise, keep warm, and adjust the pH value to 9-12; Step 1) specifically comprises: mixing the organic component R, the silicon source and water, reacting and aging to obtain a nano-silica polymer composite material suspension; In step 1), the organic component R is selected from one or more of tannic acid, gallic acid, chlorogenic acid, and propyl gallate; the silicon source is selected from one or more of sodium metasilicate pentahydrate, sodium silicate, tetraethyl silicate, and tetramethyl silicate; In step 2), the complexing agent is ferrous sulfate; The organic component R and silicon source in the A material are the same as those in the base material; The prepared Janus structural concrete reinforcing agent is Fe-(SiO2-R) x (CSHR) y Indicates, X represents 1-10, and Y represents 1-10.

2. The preparation method according to claim 1, characterized in that In step 1), the mass ratio of water, organic component R and silicon source is 200:10-100:10-50.

3. The preparation method according to claim 1, characterized in that In step 1), the reaction refers to a water bath temperature of 30-50° C. and stirring for 1-5 hours; the aging refers to a water bath temperature of 10-20° C. and aging for 1-10 hours.

4. The preparation method according to claim 1, characterized in that In step 2), the mass ratio of the nano-silica polymer composite material suspension, water, complexing agent and alkali is: 50-200: 240: 2-10: 1-10.

5. The preparation method according to claim 1 or 4, characterized in that In step 3), in material A, the mass ratio of the organic component R, the silicon source and water is 1-10:5-30:85; in material B, the mass ratio of the calcium source and water is 15-25:

85.

6. The preparation method according to claim 1 or 4, characterized in that In step 4), after the addition of materials A and B is completed, the mixture is kept warm for 3 hours and the pH value of the solution is adjusted to 9-12.

7. A Janus structural concrete reinforcing agent prepared by the preparation method according to any one of claims 1 to 6.

8. An application of the Janus structural concrete reinforcing agent according to claim 7, characterized in that: For concrete.

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