Preparation method and application of water-reducing reinforced concrete internal curing agent

Abstract

The invention discloses a preparation method and application of a water-reducing reinforced concrete internal curing agent. The specific method comprises the following steps: A, micro powder preparation; B, powder preparation; C, material preparation; and F-VA product and F-VB product preparation. The prepared concrete internal curing agent is mixed with a cement-based material, a certain amount of water is absorbed and stored in advance, and the stored water can serve as an internal water source, so that the interior of concrete has enough cement hydration water, long-term sufficient wettability is achieved, evaporation of free water of the concrete is slowed down, the cement hydration action time is prolonged, and the curing effect of the concrete is improved. According to the present invention, the concrete is provided with the denser gel crystal nucleus so as to obtain the nano-scale strain, such that the gel crystal is finer, uniform and denser, and the excellent capillary microstructure in the concrete is ensured, such that the construction performance of the fresh concrete can be improved, and the compactness, the strength and the durability of the hardened concrete can be improved; meanwhile, the shrinkage of the concrete can be effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of internal curing agents in concrete admixtures, and in particular to a preparation method and application of a water-reducing and enhanced concrete internal curing agent. Background Art

[0002] With the technological development of commercial concrete and the promotion and application of high-performance water-reducing agents, the cement consumption per cubic meter of concrete has decreased, and the water-cement ratio has also decreased accordingly, resulting in a decrease in the workability, fluidity and related construction performance of concrete, affecting the durability and stability of concrete.

[0003] The reduction of free water inside the concrete will cause the concrete to have insufficient moisture for a long time, unreasonable internal microstructure, rapid evaporation of free water, insufficient cement hydration, and inadequate hydration. More seriously, it will cause the cement hydration reaction to stop, causing the risk of shrinkage cracking of the concrete and substandard strength. Summary of the Invention

[0004] Based on the above technical problems, the purpose of the present invention is to provide a preparation method and application of a water-reducing and enhanced concrete curing agent.

[0005] The present invention provides a method for preparing a water-reducing and enhanced concrete curing agent, wherein the concrete curing agent is an F-VA product and an F-VB product, and specifically comprises the following steps:

[0006] Step 1, preparing A micropowder: adding the following raw materials in a weight ratio: 75-85% of volcanic ash material, 5-20% of saltpeter ore, and 5-10% of gypsum ore to a grinding and concentrator, grinding and air separation are performed to obtain A micropowder with a particle size of 100-400 nm, which is set aside; the volcanic ash material is two or more selected from volcanic ash, coal-fired slag, siliceous slag, silica fume, blast furnace slag, and cement-based materials;

[0007] Step 2, preparation of B powder: adding the following raw materials in a weight ratio: 70-85% active silicon dioxide and 5-15% nano-calcium oxide to a batching tank by microwave vibration, and adding 10-15% mist aqueous solution at the same time, stirring for 4.5 hours with a forced mixer at a speed of 180 r / min to obtain B powder, which is set aside; the mist aqueous solution is two or more of triisopropanolamine, ethylene glycolamine and ethylene glycol;

[0008] Step 3, preparation of material C: the following raw materials in weight ratio: 30-45% of a super absorbent resin with a particle size of 10-30 μm, 1.5-4.5% of modified HPMC, 1-3.5% of polyvinyl alcohol, 1-4.5% of redispersible VAE, 10-18% of polyethylene glycol monomethyl ether methacrylate polymer, 10-30% of PC-H polyoxyethylene ether acrylic polymer, and 5-10% of a polyurethane thickener are added separately into a container and stirred thoroughly for 2.5 hours in a forced mixer at a speed of 120 r / min to obtain material C, which is set aside;

[0009] Step 4, preparation of F-VA product: the following dry materials in weight ratio: 45-65% of A micropowder, 10-25% of B powder and 10-30% of C material are mixed and added to a blender. The mixture is stirred thoroughly for 3.5 hours with a forced blender at a speed of 120 rpm to obtain the F-VA product, which is set aside.

[0010] Step 5, preparation of F-VB product: Add the following materials in a weight ratio: 20-35% of A micropowder, 5-15% of B powder, 5-15% of C material, and 45-65% of deionized water into a container, and force stir at a speed of 120 r / min for 3.5 hours to obtain the F-VB product, which is set aside.

[0011] Furthermore, in the preparation of the A micropowder, the optimized weight ratio of the raw materials is: 78-82% of volcanic ash material, 10-15% of saltpeter ore and 6-8% of gypsum ore.

[0012] Furthermore, in the preparation of the B powder, the optimized weight ratio of the raw materials is: active silicon dioxide 73-78%, nano calcium oxide 7-12%, and mist aqueous solution 11-14%.

[0013] Furthermore, in the preparation of the C material, the optimized weight ratio of the raw materials is: 33-42% of super absorbent resin with a particle size of 10-30 μm, 1.5-3.5% of modified HPMC, 1.2-2.5% of polyvinyl alcohol, 1.5-2.0% of redispersible VAE, 12-15% of polyethylene glycol monomethyl ether methacrylate polymer, 13-28% of PC-H polyoxyethylene ether acrylic polymer and 6-8% of polyurethane thickener.

[0014] Furthermore, in the preparation of the F-VA product, the optimized dry material weight ratio is: A micropowder 50-62%, B powder 15-23% and C material 11-28%.

[0015] Furthermore, in the preparation of the F-VB product, the optimized material weight ratio is: A micropowder 24-33%, B powder 6-14%, C material 7-12% and deionized water 47-63%.

[0016] The present invention also protects the use of the above-mentioned concrete curing agent. The concrete curing agent F-VA product and F-VB product are used as concrete curing agents and are mixed with concrete of different strength grades to prepare fresh concrete.

[0017] The present invention also provides for preparing fresh concrete by mixing the above-mentioned concrete curing agent with concrete of different strength grades. In the fresh concrete formula, the amount of the concrete curing agent F-VA product and F-VB product added is 10% of the cementitious material, and the cementitious material is a total mixture of cement and mineral admixtures.

[0018] Furthermore, the fresh concrete is C30 fresh concrete, C40 fresh concrete, C50 fresh concrete or C60 fresh concrete.

[0019] Furthermore, the concrete curing agents F-VA and F-VB are used as concrete curing agents and are mixed with shotcrete to prepare fresh shotcrete, which is used in roads, railways, bridges, tunnels and civil construction. The concrete curing agents can greatly improve the early strength of shotcrete.

[0020] Compared with the existing technology, the present invention has the following beneficial effects:

[0021] The present invention incorporates F-VA or F-VB internal curing agents into cement-based materials to pre-absorb and store a certain amount of water. This stored water can serve as an "internal water source," ensuring sufficient cement hydration water within the concrete, achieving long-term, sufficient wetness, slowing the evaporation of free water in the concrete, and prolonging the cement hydration time. This provides the concrete with denser cement nuclei, resulting in nanoscale "bacteria," making the cement crystals smaller, more uniform, and denser, ensuring an excellent capillary microstructure within the concrete. This not only improves the construction performance of fresh concrete, but also enhances the density, strength, and durability of hardened concrete, while effectively reducing concrete shrinkage. Specifically, the internal hydration products and physical structure of the concrete are improved and enhanced in the following aspects:

[0022] 1. The concrete curing agent prepared by the present invention contains pozzolanic micropowder with a particle size of 100-400nm, activated silica, and an appropriate amount of cement hydration activator. When prepared into reinforced concrete, it provides the concrete with sufficient inert and active nanoscale materials, forming more abundant and dense cement nuclei with nanoscale "bacteria" performance. This accelerates the cement hydration rate, ensures more complete and perfect cement hydration, and further increases the density of the cement hydration product. It also fills the gaps between cement particles, improves and enhances the concrete microstructure, makes the concrete more compact, reduces shrinkage, increases strength, reduces cracking, and improves the concrete's durability, including frost resistance, permeability resistance, sulfate corrosion resistance, and crack resistance.

[0023] 2. The addition of highly absorbent resin with a particle size of 10-30μm and a variety of water-retaining materials can maintain the long-term humidity inside the concrete when it is prepared into fresh concrete, delay the volatilization of free water inside the concrete, improve the level of self-curing inside the fresh concrete, improve the "comprehensive performance" of the concrete curing agent, and improve the workability, water retention, fluidity and other construction properties of the fresh concrete, thereby improving the density, strength, corrosion resistance, anti-permeability and other durability of the hardened concrete.

[0024] 3. After the prepared F-VA or F-VB product is prepared into fresh concrete, more free water is released in the concrete, which greatly increases the amount of free water inside the concrete. At the same time, it ensures that the concrete is fully moist for a long time and has enough cement hydration water, making the cement hydration more complete and reducing the waste of excessive cement use. DETAILED DESCRIPTION

[0025] The technical solutions of the present invention are described clearly and completely below with reference to the embodiments. It is obvious that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0026] The specific implementation method of the present invention is as follows:

[0027] A method for preparing a water-reducing and enhanced concrete curing agent, wherein the concrete curing agent is an F-VA product or an F-VB product, specifically comprising the following steps:

[0028] Step 1, preparing A micropowder: adding the following raw materials in a weight ratio: 75-85% of volcanic ash material, 5-20% of saltpeter ore, and 5-10% of gypsum ore to a grinding and concentrator, grinding and air separation are performed to obtain A micropowder with a particle size of 100-400 nm, which is set aside; the volcanic ash material is two or more selected from volcanic ash, coal-fired slag, siliceous slag, silica fume, blast furnace slag, and cement-based materials;

[0029] Step 2, preparation of B powder: adding the following raw materials in a weight ratio: 70-85% active silicon dioxide and 5-15% nano-calcium oxide to a batching tank by microwave vibration, and adding 10-15% mist aqueous solution at the same time, stirring for 4.5 hours with a forced mixer at a speed of 180 r / min to obtain B powder, which is set aside; the mist aqueous solution is two or more of triisopropanolamine, ethylene glycolamine and ethylene glycol;

[0030] Step 3, preparation of material C: the following raw materials in weight ratio: 30-45% of a super absorbent resin with a particle size of 10-30 μm, 1.5-4.5% of modified HPMC, 1-3.5% of polyvinyl alcohol, 1-4.5% of redispersible VAE, 10-18% of polyethylene glycol monomethyl ether methacrylate polymer, 10-30% of PC-H polyoxyethylene ether acrylic polymer, and 5-10% of a polyurethane thickener are added separately into a container and stirred thoroughly for 2.5 hours in a forced mixer at a speed of 120 r / min to obtain material C, which is set aside;

[0031] Step 4, preparation of F-VA product: the following dry materials in weight ratio: 45-65% of A micropowder, 10-25% of B powder and 10-30% of C material are mixed and added to a blender. The mixture is stirred thoroughly for 3.5 hours with a forced blender at a speed of 120 rpm to obtain the F-VA product, which is set aside.

[0032] Step 5, preparation of F-VB product: Add the following materials in a weight ratio: 20-35% of A micropowder, 5-15% of B powder, 5-15% of C material, and 45-65% of deionized water into a container, and force stir at a speed of 120 r / min for 3.5 hours to obtain the F-VB product, which is set aside.

[0033] Table 1 Formula of concrete internal curing agent F-VA product

[0034]

[0035]

[0036]

[0037] Table 2 Formula of concrete internal curing agent F-VB product

[0038]

[0039]

[0040] Example 1

[0041] A preparation method of a water-reducing and enhanced concrete internal curing agent F-VA product is prepared according to the above specific steps and the formula corresponding to Example 1 in Table 1.

[0042] Example 2

[0043] A preparation method of a water-reducing and enhanced concrete internal curing agent F-VA product is prepared according to the above specific steps and the formula corresponding to Example 2 in Table 1.

[0044] Example 3

[0045] A preparation method of a water-reducing and enhanced concrete internal curing agent F-VA product is prepared according to the above specific steps and the formula corresponding to Example 3 in Table 1.

[0046] Example 4

[0047] A method for preparing a water-reducing and enhanced concrete internal curing agent F-VA product is prepared according to the above specific steps and the formula corresponding to Example 4 in Table 1.

[0048] Example 5

[0049] A preparation method of a water-reducing and enhanced concrete internal curing agent F-VA product is prepared according to the above specific steps and the formula corresponding to Example 5 in Table 1.

[0050] Example 6

[0051] A method for preparing a water-reducing and enhanced concrete internal curing agent F-VA product is prepared according to the above specific steps and the formula corresponding to Example 6 in Table 1.

[0052] Example 7

[0053] A method for preparing a water-reducing and enhanced concrete internal curing agent F-VB product is prepared according to the above specific steps and the formula corresponding to Example 7 in Table 2.

[0054] Example 8

[0055] A method for preparing a water-reducing and enhanced concrete internal curing agent F-VB product is prepared according to the above specific steps and the formula corresponding to Example 8 in Table 2.

[0056] Example 9

[0057] A method for preparing a water-reducing and enhanced concrete internal curing agent F-VB product is prepared according to the above specific steps and the formula corresponding to Example 9 in Table 2.

[0058] Example 10

[0059] A method for preparing a water-reducing and enhanced concrete internal curing agent F-VB product is prepared according to the above specific steps and the formula corresponding to Example 10 in Table 2.

[0060] Example 11

[0061] A method for preparing a water-reducing and enhanced concrete internal curing agent F-VB product is prepared according to the above specific steps and the formula corresponding to Example 11 in Table 2.

[0062] Example 12

[0063] A method for preparing a water-reducing and enhanced concrete internal curing agent F-VB product is prepared according to the above specific steps and the formula corresponding to Example 12 in Table 2.

[0064] Example 13

[0065] For the C30 fresh concrete containing internal curing agent, the internal curing agent prepared in Examples 1-12 was taken and mixed with the C30 concrete formula in an amount of 10% of the cementitious material (the total mixture of cement and mineral admixtures). Each formula was tested to measure its compressive strength and shrinkage at 7d, 28d, and 56d. The compressive strength test method was carried out in accordance with the relevant provisions of GB50010-2010, but the actual construction conditions were not simulated. The specimens after demolding were naturally cured in a natural environment. The shrinkage test was carried out in accordance with the relevant provisions of GB / T50082-2009. The blank case is a control concrete to which no water-reducing and enhanced concrete internal curing agent was added. The specific test results are shown in Table 3 below.

[0066] Table 3 Changes in concrete strength and shrinkage

[0067]

[0068] As shown in Table 3, compared with the blank group, the 56d shrinkage ratio of the concrete of Examples 1 to 12 using the concrete internal curing agent prepared by the present invention is much lower than that of the blank group, and the 7d, 28d, and 56d compressive strength values ​​are all greater than those of the blank group. This shows that the internal curing agent of the present invention has the advantages of moderate water release performance in the early, middle and late stages, a long period of free water release, and a significant self-reinforcement effect. In addition, from the test results, the application results of the internal curing agent of Example 1 are better than those of other Examples 2 to 12.

[0069] Application Example 1

[0070] The concrete curing agent F-VA product of Example 1 was used as the concrete curing agent and mixed with concrete formulations of four strength grades: C30, C40, C50, and C60. The amount of the concrete curing agent added was 10% of the cementitious material (the total mixture of cement and mineral admixtures). The blank case was a control concrete without the addition of the water-reducing and enhanced concrete curing agent. The specific test results are shown in Table 4 below.

[0071] Table 4 Concrete strength and shrinkage test results

[0072]

[0073] As shown in Table 4, compared to the blank, fresh concrete prepared using the concrete curing agent of Example 1 of the present invention exhibits advantages such as high strength, low shrinkage, and significant long-term performance gains. It is particularly effective in reducing concrete shrinkage and is suitable for concrete of all strength grades. After incorporating the internal curing agent of the present invention, the 7d, 28d, and 56d shrinkage rates were significantly higher than those of the blank. While the 7d strength of Example 1 remained essentially unchanged, the 28d and 56d compressive strengths remained high, demonstrating no reduction in concrete strength due to reduced shrinkage.

[0074] From the above comparative tests, it can be seen that after adding concrete curing agent to concrete, the amount of free water in the fresh concrete is increased, while ensuring that the concrete is fully moist for a long time, which can significantly reduce the shrinkage of the concrete and ensure that there is enough cement hydration water in the concrete, making the cement hydration more complete and effectively improving the strength of concrete at all ages.

[0075] Application Example 2

[0076] The above-mentioned concrete curing agents F-VA and F-VB products are used as concrete curing agents. After being mixed with shotcrete, they are prepared into fresh shotcrete, which is used in roads, railways, bridges, tunnels and civil construction. The concrete curing agents have a significant effect on improving the early strength of shotcrete.

[0077] The concrete curing agent F-VA product of Example 1 was used as the concrete curing agent and mixed with the C30 shotcrete formula to prepare fresh shotcrete. The amount of the concrete curing agent added was 10% of the cementitious material (the total mixture of cement and mineral admixtures). The blank case was a control shotcrete without the addition of the water-reducing and enhanced concrete curing agent. The specific test results are shown in Table 5 below.

[0078] Table 5 Test results of strength and shrinkage of fresh shotcrete

[0079]

[0080] As shown in Table 5, compared to a blank, fresh shotcrete prepared with the concrete curing agent of Example 1 of the present invention exhibited significantly higher 1-day and 28-day strengths than concrete without the water-reducing, enhanced internal curing agent when used in highways, railways, bridges, tunnels, and civil engineering applications. This demonstrates that the concrete curing agent significantly improves the early-stage strength of shotcrete.

[0081] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a water-reducing and enhanced concrete curing agent, characterized in that: The concrete curing agent is F-VA product and F-VB product, which specifically includes the following steps: Step 1, preparation of A micro powder: adding the following raw materials in weight ratio: 75-85% of volcanic ash material, 5-20% of saltpeter ore and 5-10% of gypsum ore into a grinding and selecting machine, grinding and air separation, obtaining A micro powder with a particle size of 100-400nm, and setting aside; the volcanic ash material is two or more of volcanic ash, coal-fired slag, siliceous slag, silica powder, blast furnace slag and cement-based materials; Step 2, preparation of B powder: adding the following raw materials in weight ratio: 70-85% of active silicon dioxide and 5-15% of nano calcium oxide into a batching tank by microwave vibration, and adding 10-15% of mist aqueous solution at the same time, stirring for 4.5 hours with a forced mixer at a speed of 180r / min to obtain B powder for standby use; the mist aqueous solution is two or more of triisopropanolamine, ethylene glycolamine and ethylene glycol; Step 3, preparation of material C: add the following raw materials in weight ratio: 30-45% of super absorbent resin with a particle size of 10-30 μm, 1.5-4.5% of modified HPMC, 1-3.5% of polyvinyl alcohol, 1-4.5% of redispersible VAE, 10-18% of polyethylene glycol monomethyl ether methacrylate polymer, 10-30% of PC-H polyoxyethylene ether acrylic polymer and 5-10% of polyurethane thickener into a container respectively, stir thoroughly for 2.5 hours with a forced mixer at a speed of 120 r / min to obtain material C for standby use; Step 4, preparation of F-VA product: add the following dry materials in weight ratio: 45-65% of A micro powder, 10-25% of B powder and 10-30% of C material to a blender, and stir thoroughly for 3.5 hours with a forced blender at a speed of 120 r / min to obtain F-VA product for later use; Step 5, preparation of F-VB product: add the following materials in weight ratio: 20-35% A micropowder, 5-15% B powder, 5-15% C material and 45-65% deionized water into a container respectively, and force stir at a speed of 120 r / min for 3.5 hours to obtain F-VB product for later use.

2. The method for preparing a water-reducing and enhanced concrete internal curing agent according to claim 1, characterized in that: In the preparation of the A micropowder, the optimized weight ratio of raw materials is: 78-82% of volcanic ash material, 10-15% of saltpeter ore and 6-8% of gypsum ore.

3. The method for preparing a water-reducing and enhanced concrete internal curing agent according to claim 1, characterized in that: In the preparation of the B powder, the optimized weight ratio of the raw materials is: 73-78% of active silicon dioxide, 7-12% of nano calcium oxide, and 11-14% of mist aqueous solution.

4. The method for preparing a water-reducing and enhanced concrete internal curing agent according to claim 1, characterized in that: In the preparation of the C material, the weight ratio of the raw materials after optimization is: 33-42% of highly absorbent resin with a particle size of 10-30 μm, 1.5-3.5% of modified HPMC, 1.2-2.5% of polyvinyl alcohol, 1.5-2.0% of redispersible VAE, 12-15% of polyethylene glycol monomethyl ether methacrylate polymer, 13-28% of PC-H polyoxyethylene ether acrylic polymer and 6-8% of polyurethane thickener.

5. The method for preparing a water-reducing and enhanced concrete internal curing agent according to claim 1, characterized in that: In the preparation of the F-VA product, the optimized dry material weight ratio is: A micro powder 50-62%, B powder 15-23% and C material 11-28%.

6. The method for preparing a water-reducing and enhanced concrete internal curing agent according to claim 1, characterized in that: In the preparation of the F-VB product, the optimized material weight ratio is: A micropowder 24-33%, B powder 6-14%, C material 7-12% and deionized water 47-63%.

7. Use of the water-reducing and enhanced concrete curing agent prepared according to any one of claims 1 to 6, characterized in that: The concrete curing agent F-VA product and F-VB product are used as concrete curing agents and are mixed with concrete of different strength grades to prepare fresh concrete.

8. The use according to claim 7, characterized in that: The concrete curing agent is mixed with concrete of different strength grades to prepare fresh concrete. In the fresh concrete formula, the added amount of the concrete curing agent F-VA product and F-VB product is 10% of the cementitious material, and the cementitious material is a total mixture of cement and mineral admixtures.

9. The use according to claim 8, characterized in that: The fresh concrete is C30 fresh concrete, C40 fresh concrete, C50 fresh concrete or C60 fresh concrete.

10. Use of the water-reducing and enhanced concrete curing agent prepared according to any one of claims 1 to 6, characterized in that: The concrete curing agent F-VA product and F-VB product are used as concrete curing agents and are mixed with shotcrete to prepare fresh shotcrete, which is used for roads, railways, bridges, tunnels and civil construction.

Images