Chlorine-fixing early-strength admixture for fly ash concrete and preparation method of chlorine-fixing early-strength admixture

Abstract

The invention provides a chlorine-fixing early-strength admixture for fly ash concrete and a preparation method thereof. The method comprises the following steps: adding a sodium silicate solution and a calcium nitrate solution into a sulfamate water reducing agent solution to react, and adjusting the pH value of the reacted solution to a set range to obtain a hydrated calcium silicate gel suspension; and adding an aluminum phase dissolution promoter and a sulfamate water reducing agent into the hydrated calcium silicate gel suspension to obtain the chlorine-fixing early-strength admixture for fly ash concrete. According to the method for obtaining the early strength agent with chloride ion erosion resistance through a solution precipitation method, the problem that high-alumina fly ash concrete cannot avoid chloride ion erosion is solved, the service life of the concrete is prolonged, and the engineering value is prolonged.

Description

Technical Field

[0001] The invention relates to the field of building admixtures, and in particular to a chlorine-fixing early-strengthening admixture for fly ash concrete and a preparation method thereof. Background Art

[0002] As the country vigorously promotes infrastructure construction, concrete has become the most widely used artificial stone in civil engineering. Although concrete has many advantages, considering the influence of environmental factors in which concrete is located, concrete is subject to various erosions in actual engineering, and its durability faces severe tests. Among them, the study of chloride ion erosion is an important topic in the durability design of concrete. The penetration and accumulation of chloride ions in concrete will cause the steel bars inside the concrete to rust, thereby destroying the concrete structure and seriously affecting the service life of the concrete.

[0003] A large number of studies have shown that chloride ion curing and migration inhibition of cement-based materials can improve the service life of concrete structures. That is, chemical admixtures, mineral admixtures, etc. are added to cement-based materials to enhance the curing ability and migration inhibition ability of free chloride ions, thereby reducing the free chloride ion content and preventing chloride ion migration. The chloride ion curing methods of cement-based materials can be divided into two types: physical curing and chemical curing. Physical curing is to solidify free chloride ions in the form of physical adsorption through electrostatic attraction or van der Waals force. The mechanism of chemical curing is through Cl ﹣ It mainly combines with the C3A phase and hydration products in the cement base to form Friedel salt or Kuzel salt. Both salts are stable and harmless, achieving the purpose of solidifying chloride ions.

[0004] Fly ash is the mineral residue produced after burning coal. It is a substance similar to fine powder, and its main components are inorganic substances such as silicon dioxide, aluminum oxide, and calcium oxide. Fly ash plays an important role in building materials and is usually used as an important admixture in concrete. Because it has the characteristics of high fineness, good bonding strength, and good durability, it can effectively improve the strength, compression resistance, and frost resistance of concrete. At the same time, the use of fly ash also helps to reduce the production cost of concrete and reduce pollution to the environment, so it is widely used in construction projects.

[0005] High-alumina fly ash concrete is a concrete with high-alumina fly ash as admixture, which makes full use of solid waste resources. However, this concrete is also inevitably susceptible to chloride ion corrosion. Therefore, research on improving its ability to resist chloride ion corrosion is of great significance for increasing the service life of concrete and extending the value of the project. Summary of the invention

[0006] In order to solve the problem that high-alumina fly ash concrete cannot avoid chloride ion erosion, the present invention provides a chlorine-fixing early strength admixture for fly ash concrete and a preparation method thereof, comprising:

[0007] The sodium silicate solution and the calcium nitrate solution are added to the aminosulfonate water-reducing agent solution for reaction and the pH value of the solution after the reaction is adjusted to a set range to obtain a hydrated calcium silicate gel suspension;

[0008] Aluminum phase promoter and aminosulfonate water reducing agent are added into the calcium silicate hydrate gel suspension to obtain a chlorine-fixing early strength admixture for fly ash concrete.

[0009] Preferably, the sodium silicate solution, the calcium nitrate solution and the aminosulfonate water-reducing agent solution are mixed and reacted in a weight ratio of 1:0.8-1.2:5-8.

[0010] Preferably, the aluminum phase dissolution promoter and aminosulfonate water reducer are mixed and reacted in a ratio of 5-10% to 0.5-1.5% by weight.

[0011] Preferably, the conditions of the mixed reaction include: stirring at room temperature for 20-24 hours and stirring for 1-2 hours.

[0012] Preferably, the preparation method of the calcium silicate hydrate gel suspension comprises the following steps:

[0013] The hydrated calcium silicate gel suspension is obtained by simultaneously adding 25-30 wt % of sodium silicate solution and 25-30 wt % of calcium nitrate solution to 4-6 wt % of aminosulfonate water reducing agent solution.

[0014] Preferably, the dropping time is 15-20 min.

[0015] Preferably, the preparation method of the aluminum phase chaotropic agent comprises the following steps:

[0016] The aluminum phase chaotropic agent is obtained by mixing triisopropanolamine, triethanolamine and sodium thiocyanate in a weight ratio of 1:1-3:1-3.

[0017] Based on the same inventive concept, the present invention also provides a chlorine-fixing early-strengthening admixture for fly ash concrete, which comprises sodium silicate, calcium nitrate, aminosulfonate water reducer and aluminum phase solvent in parts by weight.

[0018] Preferably, the aluminum phase chaotropic agent includes: triisopropanolamine, triethanolamine, and sodium thiocyanate.

[0019] Preferably, the dosage of the early strength admixture is 2-4% of the total amount of fly ash concrete.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention provides a method for preparing a chlorine-fixing early strength admixture for fly ash concrete, the method comprising: adding a sodium silicate solution and a calcium nitrate solution to an aminosulfonate water-reducing agent solution for reaction and adjusting the pH value of the solution after the reaction to a set range to obtain a calcium silicate hydrate gel suspension; adding an aluminum phase promoter and an aminosulfonate water-reducing agent to the calcium silicate hydrate gel suspension to obtain a chlorine-fixing early strength admixture for fly ash concrete. The present invention obtains a method for an early strength agent with chloride ion corrosion resistance by a solution precipitation method, solves the problem that high-aluminum fly ash concrete cannot avoid chloride ion corrosion, improves the service life of concrete, and extends the engineering value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention provides a flow chart of a method for preparing a chlorine-fixing early-strengthening admixture for fly ash concrete. DETAILED DESCRIPTION

[0023] In order to better understand the present invention, the content of the present invention is further described below in conjunction with the accompanying drawings and examples.

[0024] Embodiment 1:

[0025] The present invention provides a method for preparing a chlorine-fixing early-strengthening admixture for fly ash concrete, such as Figure 1 As shown, including:

[0026] Step 1: adding sodium silicate solution and calcium nitrate solution to aminosulfonate water reducer solution for reaction and adjusting the pH value of the solution after the reaction to a set range to obtain a hydrated calcium silicate gel suspension;

[0027] Step 2:

[0028] Aluminum phase promoter and aminosulfonate water reducing agent are added into the calcium silicate hydrate gel suspension to obtain a chlorine-fixing early strength admixture for fly ash concrete.

[0029] In step 1, sodium silicate solution and calcium nitrate solution are added to aminosulfonate water-reducing agent solution for reaction and pH value of the solution after the reaction is adjusted to a set range to obtain hydrated calcium silicate gel suspension, comprising:

[0030] The sodium silicate solution, calcium nitrate solution and aminosulfonate water reducer solution are mixed and reacted in a ratio of 1:0.8-1.2:5-8 by weight;

[0031] 25-30wt% sodium silicate solution and 25-30wt% calcium nitrate solution are respectively added dropwise to 4-6wt% aminosulfonate water reducer solution, wherein the mass ratio of sodium silicate solution, calcium nitrate solution and aminosulfonate water reducer solution is 1:(0.8-1.2):(5-8), and the adding time is controlled to be 15-20min. After the adding is completed, the pH value of the solution is adjusted to 11.5-11.7; and then stirred at room temperature for 20-24h to obtain a CSH gel suspension.

[0032] In this embodiment, the pH value of the solution after the reaction is adjusted to a set range, and the set range is 11.5-11.7.

[0033] In step 2, the aluminum phase promoter and aminosulfonate water reducer are added to the calcium silicate hydrate gel suspension to obtain a chlorine-fixing early strength admixture for fly ash concrete, comprising:

[0034] The aluminum phase dissolution promoter and aminosulfonate water reducer are mixed and reacted in a ratio of 5-10% to 0.5-1.5% by weight;

[0035] The conditions of the mixed reaction include: stirring at room temperature for 20-24 hours and stirring for 1-2 hours.

[0036] Add 5-10% aluminum phase promoter and 0.5-1.5% aminosulfonate water reducer (solid content is 30-35%), continue stirring for 1-2 hours, and obtain an early strength agent with resistance to chloride ion corrosion.

[0037] The aluminum phase chaotropic agent added is a mixture of triisopropanolamine, triethanolamine and sodium thiocyanate, with a mass ratio of 1:(1-3):(1-3).

[0038] Embodiment 2:

[0039] Based on the same concept, the present invention also provides a chlorine-fixing early-strengthening admixture for fly ash concrete, comprising:

[0040] Sodium silicate, calcium nitrate, aminosulfonate water reducer and aluminum phase solvent in parts by weight.

[0041] The aluminum phase chaotropic agent includes: triisopropanolamine, triethanolamine, sodium thiocyanate, including:

[0042] The aluminum phase chaotropic agent added is a mixture of triisopropanolamine, triethanolamine and sodium thiocyanate, with a mass ratio of 1:(1-3):(1-3).

[0043] The dosage of the early strength admixture is 2-4% of the total amount of fly ash concrete, including:

[0044] The fly ash concrete has a fly ash content of 20-40%. When the chlorine-fixing early strength admixture is applied to the fly ash concrete and the content is 2-4%, the chloride ion diffusion coefficient is reduced by more than 50%, the 3-day strength is increased by more than 30%, and the 28-day strength is increased by more than 10%.

[0045] Embodiment 3:

[0046] The present invention adopts sodium silicate nonahydrate, calcium nitrate tetrahydrate, triisopropanolamine (TIPA), triethanolamine (TEA), sodium thiocyanate (NaSCN) to prepare a chlorine-fixing early strength admixture for fly ash concrete, which is described in detail as follows:

[0047] Sodium silicate nonahydrate and calcium nitrate tetrahydrate are dissolved in deionized water to prepare 25-30wt% sodium silicate solution and 25-30wt% calcium nitrate solution, and then 4-6wt% aminosulfonate water reducer solution is prepared; in a 20°C water bath environment, the sodium silicate solution and calcium nitrate solution are respectively added dropwise to the aminosulfonate water reducer solution, wherein the mass ratio of the sodium silicate solution, the calcium nitrate solution, and the aminosulfonate water reducer solution is 1: (0.8-1.2): (5-8), and the dropping time is controlled to be 15-20min. After the dropwise addition is completed, the pH of the solution is adjusted to 11.5-11.7; then stirred at room temperature for 20-24h to obtain a CSH gel suspension. The raw material composition, proportion and process parameters of the CSH gel suspension in Examples 1-6 are shown in Table 1.

[0048] Table 1 Raw material composition, ratio and process parameters of C-SH gel suspension

[0049]

[0050]

[0051] Then add 5-10% aluminum phase promoter and 0.5-1.5% aminosulfonate water reducer (solid content is 30-35%) to the CSH gel suspension, and continue stirring for 1-2 hours to obtain an early strength agent with resistance to chloride ion corrosion. The composition and addition amount of the aluminum phase promoter of the early strength agent with resistance to chloride ion corrosion in Examples 1-6, the solid content and addition amount of the aminosulfonate water reducer, and the stirring time are shown in Table 2, wherein the addition amounts of the aluminum phase promoter and the aminosulfonate water reducer are calculated as a percentage of the mass of the CSH gel suspension.

[0052] Table 2 Preparation process parameters of early strength agent with resistance to chloride ion corrosion

[0053]

[0054] Preparation of fly ash concrete: fly ash, 42.5 ordinary Portland cement, sand, stone and water are mixed evenly to make concrete, wherein the raw material ratio is cementitious material (fly ash, 42.5 ordinary Portland cement): 434kg / m3, sand: 707kg / m3, stone: 1062kg / m3, water: 173.6kg / m3, and the water-cement ratio is 0.4; 2-4% of anti-chloride ion corrosion early strength agent is added at the same time. The concrete prepared in each embodiment and comparative example is tested for chloride ion diffusion coefficient according to GB / T 50082-2009 "Test Method for Long-term Performance and Durability of Ordinary Concrete", and a 150mm×150mm×150mm cubic specimen is formed according to the "Standard for Test Method for Mechanical Properties of Ordinary Concrete" for compressive strength test. The fly ash dosage, early strength agent dosage, chloride ion diffusion coefficient and compressive strength of the fly ash concrete in Examples 1-6 and Comparative Examples 1-3 are shown in Table 2, wherein the fly ash dosage is calculated based on the mass of cement replaced.

[0055]

[0056] From the data of ion diffusion coefficient and compressive strength of the comparative example, it can be seen that when 2-4% of the admixture prepared by the present invention for improving the resistance to chloride ion corrosion is added to fly ash concrete, the chloride ion diffusion coefficient of the concrete is reduced by more than 50%, the 3-day strength is increased by more than 30%, and the 28-day strength is increased by more than 10%. The resistance to chloride ion corrosion and early strength of fly ash concrete are significantly improved, and the later strength development is also improved. The early strength agent with resistance to chloride ion corrosion provided by the present invention significantly improves the utilization efficiency of fly ash in concrete and better promotes the utilization of solid waste.

[0057] Obviously, the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0059] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0060] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0061] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0062] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A method for preparing a chlorine-fixing early strength admixture for fly ash concrete, characterized in that , the method comprises: The sodium silicate solution and the calcium nitrate solution are added to the aminosulfonate water-reducing agent solution for reaction and the pH value of the solution after the reaction is adjusted to a set range to obtain a hydrated calcium silicate gel suspension; Aluminum phase promoter and aminosulfonate water reducing agent are added into the calcium silicate hydrate gel suspension to obtain a chlorine-fixing early strength admixture for fly ash concrete.

2. The method for preparing a chlorine-fixing early strength admixture for fly ash concrete according to claim 1, characterized in that: The sodium silicate solution, calcium nitrate solution and aminosulfonate water reducing agent solution are mixed and reacted in a weight ratio of 1:0.8-1.2:5-8.

3. The method for preparing a chlorine-fixing early strength admixture for fly ash concrete according to claim 2, characterized in that: The aluminum phase dispersant and aminosulfonate water reducer are mixed and reacted in a ratio of 5-10% to 0.5-1.5% by weight.

4. The method for preparing a chlorine-fixing early-strengthening admixture for fly ash concrete as claimed in claim 3, characterized in that: The conditions of the mixed reaction include: stirring at room temperature for 20-24 hours and stirring for 1-2 hours.

5. The method for preparing a chlorine-fixing early strength admixture for fly ash concrete according to claim 1, characterized in that: The preparation method of calcium silicate hydrate gel suspension comprises the following steps: The hydrated calcium silicate gel suspension is obtained by simultaneously adding 25-30 wt % of sodium silicate solution and 25-30 wt % of calcium nitrate solution to 4-6 wt % of aminosulfonate water reducing agent solution.

6. The method for preparing a chlorine-fixing early strength admixture for fly ash concrete as claimed in claim 5, characterized in that: The dropping time is 15-20 min.

7. The method for preparing a chlorine-fixing early-strengthening admixture for fly ash concrete as claimed in claim 3, characterized in that: The preparation method of the aluminum phase chaotropic agent comprises the following steps: The aluminum phase chaotropic agent is obtained by mixing triisopropanolamine, triethanolamine and sodium thiocyanate in a weight ratio of 1:1-3:1-3.

8. A chlorine-fixing early-strengthening admixture for fly ash concrete, characterized in that: The chlorine-fixing early-strengthening admixture for fly ash concrete comprises, by weight, sodium silicate, calcium nitrate, aminosulfonate water-reducing agent and aluminum phase solvent.

9. The chlorine-fixing early-strengthening admixture for fly ash concrete as claimed in claim 8, characterized in that: The aluminum phase chaotropic agent includes: triisopropanolamine, triethanolamine and sodium thiocyanate.

10. A chlorine-fixing early-strengthening admixture for fly ash concrete as claimed in claim 9, characterized in that: The dosage of the early strength admixture is 2-4% of the total amount of fly ash concrete.

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