Method for regulating and controlling dissolution rate of tricalcium silicate in erosion ion environment

Abstract

The invention discloses a method for regulating and controlling the dissolution rate of tricalcium silicate in an erosive ion environment. According to the method, nano sol is added into tricalcium silicate in an erosive ion environment containing magnesium ions and chloride ions, and ultrasonic catalysis is assisted, so that the dissolution rate of tricalcium silicate is regulated and controlled, a hydration system of the cementing material is stabilized, the influence of erosive ions on early dissolution and long-term durability of the cementing material is relieved, and the service life of the cementing material is prolonged. The application of the cementing material in ocean engineering is facilitated.

Description

Technical Field

[0001] The invention belongs to the field of civil engineering materials and relates to a method for regulating the dissolution rate of tricalcium silicate in a corrosive ion environment. Background Art

[0002] Magnesium ions and chloride ions are one of the main corrosive media in seawater. For a long time, it has been very common for marine concrete structures to suffer from diseases due to the effects of magnesium ions and chloride ions in seawater. The main manifestation is the inhibition of the dissolution of tricalcium silicate (C3S) by magnesium ions and chloride ions, which ultimately manifests as surface dissolution and complete collapse of the surface cementitious structure, resulting in reduced long-term durability of cement concrete.

[0003] At present, common methods for regulating the dissolution of cement minerals include: improving the durability and safety of concrete structures by selecting appropriate cement types, adding admixtures, optimizing concrete mix ratios, strengthening concrete protective layers, etc. However, these methods have obvious defects in practical applications, and in practical applications, factors such as engineering costs, technical difficulties, environmental impacts, and long-term effects need to be comprehensively considered. In addition, the existing technology has limited means for regulating the dissolution of tricalcium silicate, the main mineral of cement, and it is difficult to effectively regulate the dissolution rate of tricalcium silicate in seawater, thereby failing to fundamentally promote the surface dissolution of cementitious materials and the stability of the surface cementitious structure.

[0004] Therefore, it has become an urgent problem to develop a technology that can effectively regulate the dissolution of tricalcium silicate in the seawater corrosive ion environment, thereby promoting the hydration process of cementitious materials to cope with the impact of marine corrosive ions on the early dissolution and long-term durability of cementitious materials. Summary of the invention

[0005] The object of the present invention is to provide a method for regulating the dissolution rate of tricalcium silicate in an aggressive ion environment.

[0006] The technical solution for achieving the purpose of the present invention is as follows:

[0007] A method for regulating the dissolution rate of tricalcium silicate in an aggressive ion environment comprises the following steps:

[0008] Nanosol is added to tricalcium silicate in a corrosive ion environment for modification, and ultrasonic wave assists catalysis to promote the dissolution process of tricalcium silicate. The nanosol is selected from one or more of nano silica sol and aluminum sol, the ultrasonic power is 80-300HZ, and the catalytic reaction temperature is 20-50℃.

[0009] Furthermore, the corrosive ion environment is a liquid environment containing one or more of magnesium ions and chloride ions, such as seawater, wherein the magnesium ion concentration is 0.02-0.06 mol / L and the chloride ion concentration is 0.4-0.6 mol / L.

[0010] Furthermore, the nano-silica sol is a dispersion of nano-scale silicon dioxide particles in water or solvent, with a particle size of 20 to 40 nm, a solid content of 40 to 50%, and an alkaline solution with a pH greater than 9.

[0011] Furthermore, the nano-aluminum sol is a dispersion of nano-scale aluminum oxide particles in water or solvent, with a particle size of 10 to 20 nm, a solid content of 15 to 30%, and an alkaline solution with a pH greater than 8.

[0012] Further, the dosage of nano silica sol or nano silica alumina sol is 1% to 10%. In the specific embodiment of the present invention, the dosage is 5% as an example. Preferably, the dosage of nano silica sol is 3% and the dosage of alumina sol is 2%.

[0013] Compared with the prior art, the principles and advantages of the present invention are as follows:

[0014] (1) The present invention improves the dissolution process of tricalcium silicate in an environment of corrosive ions such as magnesium ions and chloride ions by adding modifiers such as silica sol and aluminum sol. The nanoparticles act as catalysts or reaction media to accelerate the reaction rate of tricalcium silicate with water, thereby promoting its dissolution. On the other hand, the colloidal properties of the nanosol will change the environment of the solution, such as pH value, ionic strength, etc., thereby affecting the dissolution equilibrium of tricalcium silicate. Therefore, by adjusting the amount and type of sol added, the solubility of tricalcium silicate can be fundamentally regulated.

[0015] (2) The silica sol and alumina sol used in the present invention can react chemically with the hydration products to generate more stable and dense product structures. These dense product structures can fill the pores in the cement paste and improve the density and strength of the paste. By accelerating the hydration rate and optimizing the hydration products, nanoparticles can significantly improve the early and late strength of cement-based materials. At the same time, nanosols can also significantly improve the durability, impermeability and crack resistance of cement-based materials.

[0016] (3) Ultrasonic waves can destroy the microstructure of the surface of tricalcium silicate, increase its specific surface area, and thus accelerate dissolution. When ultrasonic waves propagate in liquid, they will produce cavitation effects, mechanical effects, and thermal effects, which work together to significantly increase the dissolution rate of tricalcium silicate.

[0017] (4) Another important advantage of ultrasonic-assisted dissolution is the high-speed micro-vortex effect, micro-impact shear effect and ultrasonic oscillation effect generated after the addition of nano-silicate aluminum sol modifier. These effects can increase the movement speed and collision frequency of the particles in the solution, making the nano-sol particles in the solution more evenly distributed and reducing agglomeration, thereby increasing the contact area between the surface of tricalcium silicate and the nano-sol, further promoting the dissolution reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 is the silicon ion concentration curve at different dissolution times in the embodiment and the comparative example.

[0019] Figure 2 Calcium ion concentration curves at different dissolution times in the embodiments and comparative examples. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0021] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used are all commercially available unless otherwise specified.

[0022] In the following examples and comparative examples, the specific steps of solution preparation, dissolution experiment and performance test are as follows:

[0023] (1) Preparation of corrosive ions and nano-silica-alumina sol: MgCl2 solutions were prepared from deionized water and analytically pure MgCl2; the silica sol used in the experiment was mainly composed of SiO2, with a solid content of 42.25%, a particle size of 30 nm, and a pH value of 9.9; the aluminum sol was mainly composed of Al2O3, with a solid content of 21.45%, a particle size of 10-15 nm, and a pH value of 8.9; when preparing the tricalcium silicate solution, the solid-liquid ratio needed to take into account the removal of the aluminum sol and the water content of the silica sol.

[0024] (2) Dissolution: Fill the flask with 1500mL of deionized water and silicon and aluminum sols. In order to effectively avoid the precipitation of by-products such as CSH, quickly add 0.15g of C3S powder into the flask. In order to ensure the stability of the solution volume, two peristaltic pumps with the same speed are introduced at both ends of the four-necked flask to ensure the same amount of continuous input and extraction of the reaction solution. At the same time, in order to prevent the carbonization phenomenon that may occur during the experiment, nitrogen is continuously introduced into the four-necked flask to maintain an inert gas environment. Then, ultrasonic sonication is performed at 20-50°C for different times. After obtaining the solution at a specific time point, it is quickly purified through a filter with a pore size of 0.2mm, and 0.5mL of dilute nitric acid with a concentration of 5% (mass fraction) is added to the sample to maintain the stability of the concentration of each ion in the solution. At the same time, the microscopic morphology of C3S solid at a fixed age is tested.

[0025] (3) Dissolution performance control test: The concentration changes of calcium ions and silicon ions released by the dissolution of C3S were observed by inductively coupled plasma emission spectrometry (ICP) to determine the dissolution rate of C3S under different environments.

[0026] Example 1

[0027] Take 0.15g tricalcium silicate sample and disperse it in 1500ml mixed solution containing 0.27mol / L MgCl2 and 5% silica sol. Ultrasonicate is applied at 30℃ and 100Hz for 10s, 60s, 300s and 1800s respectively to obtain the dissolved solution for testing, and analyze the changes in ion concentration in the solution.

[0028] Example 2

[0029] Take 0.15g of tricalcium silicate sample and disperse it in 1500ml of a mixed solution containing 0.27mol / L MgCl2 and 5% aluminum sol. Ultrasonicate is applied at 30℃ and an ultrasonic power of 100HZ for 10s, 60s, 300s, and 1800s respectively to obtain the dissolved solution for testing, and the changes in ion concentration in the solution are analyzed.

[0030] Example 3

[0031] Take 0.15g tricalcium silicate sample and disperse it in 1500ml mixed solution containing 0.27mol / L MgCl2, 3% silica sol and 2% aluminum sol. Ultrasonicate is applied at 30℃ and 100Hz for 10s, 60s, 300s and 1800s respectively to obtain the dissolved solution for testing, and the changes in ion concentration in the solution are analyzed.

[0032] Comparative Example 1

[0033] Take 0.15g tricalcium silicate sample and disperse it in 1500ml solution containing 0.27mol / L MgCl2. Obtain the dissolved solution for testing at 10s, 60s, 300s and 1800s respectively, and analyze the changes in ion concentration in the solution.

[0034] Comparative Example 2

[0035] Take 0.15g of tricalcium silicate sample and disperse it in 1500ml of a mixed solution containing 0.27mol / L MgCl2 and 5% silica sol. Obtain the dissolved solution for testing at 10s, 60s, 300s, and 1800s respectively, and analyze the changes in ion concentration in the solution.

[0036] Comparative Example 3

[0037] Take 0.15g of tricalcium silicate sample and disperse it in 1500ml of a mixed solution containing 0.27mol / L MgCl2 and 5% aluminum sol. Obtain the dissolved solution for testing at 10s, 60s, 300s, and 1800s, respectively, and analyze the changes in ion concentration in the solution.

[0038] The calcium ion and silicon ion concentration curves of Examples 1 to 3 and Comparative Examples 1 to 3 are as follows: Figure 1 and 2 As shown, in comparative example 1, the initial concentrations of silicon ions and calcium ions are only about 2.5 mg / L and 8 mg / L, and increase with the increase of dissolution time. After 5% silica sol and aluminum sol are added to the solution, the concentrations of calcium ions and silicon ions increase significantly. In a mixed solution containing 0.27 mol / L MgCl2 and 5% silica sol and aluminum sol, the concentrations of silicon ions and calcium ions increase to 12.7 mg / L when C3S is dissolved for 10s. After ultrasonic assisted treatment is used in the comparative example, the ion concentration increases significantly. The initial silicon ion and calcium ion concentrations in Examples 1 and 2 increase to more than 20 mol / L, respectively. The ion concentration increases with the increase of dissolution time. When silica sol and aluminum sol are added in combination and assisted by ultrasonic treatment, the ion concentration increases more significantly. This shows that the addition of silica sol and aluminum sol after ultrasonic assisted treatment can further improve the dissolution rate of tricalcium silicate.

[0039] 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, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for regulating the dissolution rate of tricalcium silicate in an aggressive ion environment, characterized in that: The following steps are involved: Nanosol is added to tricalcium silicate in a corrosive ion environment for modification, and ultrasonic wave-assisted catalysis is used to promote the dissolution process of tricalcium silicate. The nanosol is selected from one or more of nano silica sol and aluminum sol, the ultrasonic power is 80-300 Hz, and the catalytic reaction temperature is 20-50°C.

2. The method according to claim 1, characterized in that The corrosive ion environment is a liquid environment containing one or more of magnesium ions and chloride ions.

3. The method according to claim 1, characterized in that The corrosive ion environment is seawater.

4. The method according to claim 1, characterized in that: In the corrosive ion environment, the magnesium ion concentration is 0.02~0.06mol / L, and the chloride ion concentration is 0.4~0.6mol / L.

5. The method according to claim 1, characterized in that: Nano-silica sol is a dispersion of nano-scale silicon dioxide particles in water or solvent, with a particle size of 20~40nm, a solid content of 40~50%, and an alkaline solution with a pH greater than 9.

6. The method according to claim 1, characterized in that Nano-aluminum sol is a dispersion of nano-scale aluminum oxide particles in water or solvent, with a particle size of 10-20 nm, a solid content of 15-30%, and an alkaline solution with a pH greater than 8.

7. The method according to claim 1, characterized in that The dosage of nano silica sol or nano silica aluminum sol is 1%~10%.

8. The method according to claim 1, characterized in that: The dosage of nano silica sol or nano silica aluminum sol is 5%.

9. The method according to claim 1, characterized in that: The dosage of nano silica sol is 3%, and the dosage of aluminum sol is 2%.

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