Adsorption-induced transport type hydraulic lime suspension and method for its production

Abstract

The application provides an adsorption-induced transmission type hydraulic lime suspension and a preparation method thereof, and belongs to the technical field of building materials. The application uses the knowledge of suspension particle dynamics, selects spherical micro-nano pozzolanic materials as the hydraulic component to promote the kinetic stability of the hydraulic lime suspension and the permeability of the hydraulic lime suspension in the earthen site. However, the specific surface area of the regular spherical particles is relatively small, the adsorption in the earthen site is small, and the regular spherical particles are prone to return migration to the surface of the earthen site to form whitening as the solvent evaporates. The application uses the alkali activation and hydrothermal synthesis method to load the silicon / aluminum gel and zeolite with super-large specific surface area on the surface of the pozzolanic material, plays an adsorption-induced transmission role, realizes the deep penetration of the hydraulic lime suspension in the earthen site, and avoids the return migration phenomenon.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of building materials, and particularly relates to an adsorption-induced transmission type hydraulic lime suspension and a preparation method thereof. BACKGROUND

[0002] Historical and cultural heritage is a valuable resource that cannot be regenerated or replaced. The research and application of protection materials for earthen sites in the current drought environment have been relatively mature. The reinforcement and protection of earthen sites in humid environments are recognized as technical problems at home and abroad. Influenced by factors such as water erosion, penetration, and freezing, earthen sites in humid environments often exhibit more serious and complex diseases such as swelling, cracking, and surface layer peeling. High modulus potassium silicate solution (PS) and acrylic resin, which have made substantial progress in the protection of earthen sites in arid environments, have been proven to be unsuitable for the reinforcement and protection of earthen sites in humid environments.

[0003] In line with the principles of "material compatibility" and "repairing old things as they were", the use of the above-mentioned organic materials to repair earthen sites with lime has entered the field of view of cultural heritage workers. However, such ancient mortars have poor permeability, slow solidification speed, and quality is difficult to control, and cannot change the current situation of developing protection materials for earthen sites on a case-by-case basis with large amounts of testing. Italian scholars have proposed using the nano-size effect of lime to improve its permeability, and hybrid nano-lime doped with zinc oxide quantum dots or graphene quantum dots has been used for the protection and repair of murals and paper. However, nano-lime is prone to accumulate on the surface of cultural relics, has slow carbonization, large shrinkage, and is expensive, which has great limitations when used for the repair of large-volume earthen sites such as city walls and mausoleums.

[0004] The unique dual-hardening characteristics of hydraulic lime, namely hydraulicity and air hardening, make it exhibit excellent durability under high humidity conditions, and it is compatible with the physicochemical properties of earthen site materials, making it an ideal material for the protection of earthen sites in humid environments. When hydraulic lime that meets the strength and weather resistance requirements is prepared into a slurry, the phenomena of low solubility of effective components and poor stability of particle distribution will occur, and when it is applied to the protection of earthen sites, the common problems of lime-based materials will inevitably occur, namely low effective penetration, uneven distribution, and poor cementation and solidification effect with the weathered layer of earthen sites. SUMMARY

[0005] To solve the above technical problems, the present application provides an adsorption-induced transport type hydraulic lime suspension and a preparation method thereof. The present application uses the knowledge of suspension particle dynamics to select spherical micro-nano pozzolanic materials as hydraulic components to promote the kinetic stability of the blended hydraulic lime suspension and its penetration in the soil site. However, the specific surface area of regular spherical particles is relatively small, the adsorption in the soil site is small, and it is easy to migrate back to the surface of the soil site to form whitening with solvent evaporation. The present application uses alkali activation and hydrothermal synthesis to load silicon / aluminum gel and zeolite with super large specific surface area on the surface of the pozzolanic material, plays an adsorption-induced transport role, realizes deep penetration of the hydraulic lime suspension in the soil site, and avoids the back migration phenomenon.

[0006] Compared with patent CN 114507055 A, the present application loads a composite structure of silicon / aluminum gel and zeolite on the surface of the construction material, and the super large specific surface area and porous structure of the silicon / aluminum gel and zeolite can strongly adsorb on the surface of the soil site particles to achieve an induced transport effect. The specific macroscopic performance is deep penetration and no back migration. Patent CN 114507055 A cannot achieve this effect.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0008] One of the technical solutions of the present application is:

[0009] An adsorption-induced transport type hydraulic lime suspension, comprising the following components: nano calcium hydroxide, spherical micro-nano pozzolanic material, sodium hydroxide, dispersant and water.

[0010] Further, the adsorption-induced transport type hydraulic lime suspension comprises the following components according to mass fraction: 50-75 parts of nano calcium hydroxide, 20-35 parts of spherical micro-nano pozzolanic material, 3-5 parts of sodium hydroxide, 0.4-0.8 parts of dispersant and 200-400 parts of water.

[0011] Further, the spherical micro-nano pozzolanic material comprises nano-silicon dioxide, silica fume and ultra-fine fly ash with spherical structure and continuous gradient distribution of particle size.

[0012] Further, the spherical micro-nano pozzolanic material comprises 15-25 parts of ultra-fine fly ash, 5-10 parts of silica fume and 1-3 parts of nano-silicon dioxide according to mass fraction.

[0013] Further, the median particle size of the ultra-fine fly ash is 1-3 μm, and the specific surface area is not less than 800 m 2 / kg; the average particle size of the silica fume is less than 1 μm; and the average particle size of the nano-silicon dioxide is less than 50 nm.

[0014] Further, the D50 of the nano calcium hydroxide is less than 600nm. 90 Further, the D50 of the nano calcium hydroxide is less than 600nm.

[0015] Further, the dispersant includes 0.2-0.3 parts of polysorbate, 0.1-0.2 parts of glycerol and 0.1-0.3 parts of water reducing agent by mass fraction.

[0016] The second technical solution of the present application is:

[0017] A preparation method of the adsorption-induced transport type hydraulic lime suspension, comprising the following steps:

[0018] Sodium hydroxide is mixed with spherical micro-nano-pozzolanic material to prepare a high-activity solution of silicon / aluminum gel and zeolite phase by a hydrothermal synthesis method;

[0019] The high-activity solution of silicon / aluminum gel and zeolite phase, the remaining water and the nano calcium hydroxide are mixed, and a dispersant is added and stirred uniformly to obtain the adsorption-induced transport type hydraulic lime suspension.

[0020] Further, the mass ratio of sodium hydroxide to water is (3-5) : 20.

[0021] In the hydrothermal synthesis method, the temperature of hydrothermal synthesis is 90℃, and the time is 15-25min; the hydrothermal synthesis process is carried out under stirring condition, and the rotating speed is 800r / min.

[0022] Further, the stirring after adding the dispersant is carried out under ultrasonic condition, and the ultrasonic dispersion is carried out for 30min.

[0023] The third technical solution of the present application is:

[0024] The adsorption-induced transport type hydraulic lime suspension is preferably used in the repair of earthen sites.

[0025] Compared with the prior art, the present application has the following advantages and technical effects:

[0026] The present application selects nano-silicon dioxide, silica fume and ultra-fine fly ash with spherical structure and continuous gradient distribution of particle size as the hydraulic component, and uses nano calcium hydroxide as the air-hardening component to form a micro-nano blended hydraulic lime material, which is beneficial to the deep penetration of effective components in the earthen site; the alkali activation and hydrothermal synthesis method are used to load silicon / aluminum gel and zeolite with super-large specific surface area and porous structure on the surface of the pozzolanic material, and the strong adsorption of the silicon / aluminum gel and zeolite on the surface of the earthen site particles is used to induce the deep penetration of the effective components of the hydraulic lime in the earthen site, and the effective components will not migrate to the surface of the earthen site to cause color difference.

[0027] The present application is prepared by scientific research and practice inspection, and successfully prepares the water hardening lime suspension which can be used for the surface reinforcement of the earthen site by the combined use of the high adsorption of amorphous silicon / aluminum gel and zeolite and the kinetic stability and deep penetration of spherical micro-nano volcanic ash material, and the effective protection of the earthen site can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The illustrations, together with the description, serve to explain the application, but are not intended to limit the application in any way. In the drawings:

[0029] Figure 1 Preparation flow chart of the adsorption induction transmission type water hardening lime suspension of the present application.

[0030] Figure 2 SEM atlas of nano-silicon dioxide (a), silica ash (b) and ultra-fine fly ash (c) used in the embodiment of the present application;

[0031] Figure 3 SEM of amorphous silicon / aluminum gel (left) and zeolite (right) attached to the surface of the volcanic ash material in the high volcanic ash activity solution prepared by the present application;

[0032] Figure 4 Penetration depth test chart of the water hardening lime suspension of Example 1 in the earthen matrix;

[0033] Figure 5 Penetration depth test result chart of different examples and comparative examples;

[0034] Figure 6 Appearance photos of the original earthen matrix (original matrix) and the reinforced earthen matrix. DETAILED DESCRIPTION

[0035] The various illustrative embodiments of the present application will now be described in detail in connection with the following figures. This description is not to be taken in a limiting sense but is made merely for the purpose of providing a full and enabling disclosure of the application. The detailed description set forth below in connection with the appended drawings describes exemplary embodiments and does not represent the only embodiments in which the application can be practiced.

[0036] It should be understood that the terms used herein are merely descriptive, but that the application should not be construed as being limited thereto. In addition, with respect to numerical ranges in the present application, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any stated value or stated range, as well as each individual value within the stated range, is also encompassed within the scope of the present application. The upper and lower limits of these smaller ranges can independently be included or excluded in the range.

[0037] All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains unless otherwise specifically defined herein. Although preferred methods and materials are described herein, any method and material similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe in full the methods and / or materials which are described herein. In case of conflict between the content of the specification and that of any document incorporated herein by reference, the content of the specification prevails.

[0038] Many modifications and variations of the present application described in the specification are possible without departing from the scope or spirit of the application. Other implementations of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples are illustrative only.

[0039] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean including, but not limited to.

[0040] All raw materials used in the embodiments of the present application are commercially available.

[0041] The "parts" used in the embodiments of the present application are "mass parts" unless otherwise specified.

[0042] The preparation flow chart of the adsorption-induced transport type hydraulic lime suspension of the present application is shown in Figure 1 .

[0043] The technical solutions of the present application are further illustrated by the following examples.

[0044] The raw materials used in the following examples of the present application and their properties are as follows:

[0045] Nano-silica with a specific surface area of 380 m 2 / g, silica fume with a specific surface area of 15 m 2 / g, and ultra-fine fly ash (sphericity ≥ 80%, silicon oxide content ≥ 40%, aluminum oxide content ≥ 30%, loss on ignition ≤ 6%) with a median particle size (D 50 ) of 2.33 μm. Their micro-morphologies are shown in Figure 2 .

[0046] Nano calcium hydroxide: nano calcium hydroxide with a median particle size (D 90 ) of 550 nm.

[0047] Sodium hydroxide: commercially available solid industrial caustic soda with a mass fraction of more than 96 wt.%.

[0048] Water reducing agent: polycarboxylic acid water reducing agent Point-TS8.

[0049] Water: tap water.

[0050] The soil matrix in the embodiments of the present application adopts silty clay with a plasticity index of 10-17, and a 5cm x 5cm x 2cm cubic test block is prepared and subjected to weathering treatment so that its density is 1.9g / cm 3 .

[0051] Examples 1-4

[0052] In Examples 1-4, the raw materials of the adsorption-induced transport type hydraulic lime suspension include the following components in mass fraction: nano calcium hydroxide 50-75 parts, nano silicon dioxide 1-3 parts, silica fume 5-10 parts, ultra-fine fly ash 15-25 parts, sodium hydroxide 3-5 parts, polysorbate 0.2-0.3 parts, glycerol 0.1-0.2 parts, water reducing agent 0.1-0.3 parts, and water 200-400 parts (see Table 1 for specific components and proportions in each example).

[0053] The specific preparation method includes two steps:

[0054] (1) Sodium hydroxide is prepared into a sodium hydroxide solution, and the sodium hydroxide solution and spherical micro-nano pozzolan material are mixed, dissolved and heated at 80°C and 800r / min for 20min using a magnetic stirrer, and after cooling, a high pozzolan activity solution loaded with silicon / aluminum gel and zeolite phase is obtained;

[0055] (2) The high pozzolan activity solution and nano calcium hydroxide are mixed, and a dispersant is added and ultrasonically dispersed for 30min to obtain the adsorption-induced transport type hydraulic lime suspension.

[0056] Table 1: Mix proportion of adsorption-induced transport type hydraulic lime suspension (in mass fraction)

[0057]

[0058] The adsorption-induced transport type hydraulic lime suspension (hereinafter referred to as suspension) prepared in Examples 1-4 above is subjected to performance testing, and the performance testing method is as follows:

[0059] (1) Suspension bleeding amount test: 100mL of prepared suspension is immediately injected into the carrier cylinder, and then sealed with a plastic template. These carrier cylinders are placed on a water platform, and the stratification phenomenon is observed every 30 minutes. The separation interface between the supernatant and the lower suspension is recorded as Vt(mL). Therefore, the bleeding amount Vb(mL) of the suspension can be obtained by formula (1).

[0060] V b =100-V t (1)

[0061] (2) Penetration depth test: As shown in Fig. 2, the soil matrix was sprayed with phenolphthalein solution in advance using the principle that phenolphthalein changes color in the presence of alkali. Then, 20 g of the suspension was uniformly brushed on the side surface of the soil matrix (except for the top and bottom top), and the color change of the upper and lower surfaces of the samples was observed. When the purple area no longer spread, the width of the color boundary starting from the edge was measured, and the penetration depth was calculated according to the average value of the four measurement data. Figure 4

[0062] (3) Surface color difference test: The color parameters of the original and reinforced soil matrix were measured using a precision colorimeter, and the total color difference between them was calculated according to the color coordinate system of the CIE 1976 (L*a*b) color space shown in Table 2.

[0063] (4) Surface hardness test: The surface hardness of the reinforced soil matrix was measured with a Shore hardness tester.

[0064] (5) Water vapor transmission rate: A plastic bottle with an opening diameter of 25 mm and a capacity of 50 mL was selected as the container, and was filled with 40 mL of deionized water; then, the reinforced soil matrix was placed on the bottle neck, and the interface between the sample and the bottle and the glass slide of the sample were sealed with plastic tape. Subsequently, the prepared steam transmission device was weighed and recorded, and was placed in a constant temperature and humidity chamber. The weight of the device was recorded after 24 hours to calculate the mass loss.

[0065] Table 2 Properties of the suspension and test results of the properties of the reinforced soil matrix

[0066]

[0067] The results show that the adsorption-induced transport type hydraulic lime suspension prepared in the embodiment has high particle stability; when the hydraulic lime suspension is used for soil site reinforcement, it can penetrate deeply into the soil site, effectively improve the surface hardness of the soil site, and has little effect on the surface color and air permeability of the soil site, and is a protective material that can meet the mechanical properties and compatibility requirements in soil site reinforcement engineering.

[0068] Comparative Example 1

[0069] The same as Example 4, except that no high-pozzolanic activity solution was added, and the nano calcium hydroxide was directly dissolved in the water dispersant, dispersed by ultrasonic for 30 min, and then the surface of the soil matrix was reinforced.

[0070] The results show that the suspension has a 12.8 mL water bleeding amount in 12 h, a penetration depth of 4.53 mm, a surface color difference of 9.35, a surface hardness of 11.2 HA, and a 24 h air permeability of 0.45 g.

[0071] Comparative Example 2​

[0072] The raw material ratio is the same as that of Example 4, except that the volcanic ash material (i.e. nano-silica, silica ash and ultra-fine fly ash) is directly dissolved in the water dispersant with nano-calcium hydroxide, and then dispersed for 30 min by ultrasonic, and then the surface of the soil matrix is reinforced.

[0073] The results show that the bleeding amount of the suspension is 10.4 mL, the penetration depth is 5.52 mm, the surface color difference is 7.21, the surface hardness is 14.8 HA, and the 24 h air permeability is 0.45 g.

[0074] Figure 5 For the penetration depth test chart of the hydraulic lime suspension of different examples and comparative examples in the soil matrix, it can be seen that the penetration depth of the two comparative examples is about 5 mm, and the penetration depth of Examples 1-4 is about 10 mm, which is significantly higher than that of the comparative examples, indicating that the hydraulic lime suspension of the present application has good penetration in the soil matrix.

[0075] Figure 6 For the apparent photos of the original soil matrix (original matrix) and the reinforced soil matrix, it can be seen that the surface of the two comparative examples is covered with a layer of white hydraulic lime, and the color difference is serious; while the color difference between the surface of Examples 1 and 2 and the original matrix is smaller, which is within the acceptable range.

[0076] From the above results, it can be seen that when the hydraulic lime suspension prepared by the examples is used for soil site reinforcement, it can penetrate deeply in the soil site, effectively improve the surface hardness of the soil site, and has little effect on the surface color and air permeability of the soil site. The penetration depth and surface hardness of the soil aggregate matrix reinforced by the suspension of Comparative Example 1 are smaller, the color difference is large, and the air permeability is poor; the performance of the soil aggregate matrix reinforced by the suspension of Comparative Example 2 is slightly improved compared with Comparative Example 1, but compared with the examples, it still has the disadvantages of shallow penetration, low surface hardness, large color difference and poor air permeability.

[0077] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An adsorptive induced transport type hydraulic lime suspension, characterized in that, According to the mass fraction, the nanometer calcium hydroxide 50-75 parts, spherical micro-nano-pozzolanic material 20-35 parts, sodium hydroxide 3-5 parts, dispersant 0.4-0.8 parts and water 200-400 parts are mixed. The spherical micro-nano volcanic ash material is nano-silicon dioxide, silica ash and ultra-fine fly ash; the median particle size of the ultra-fine fly ash is 1-3 microns, the specific surface area is not less than 800 m 2 / kg; the average particle size of the silica ash is less than 1 micron; and the average particle size of the nano-silicon dioxide is less than 50 nm. The D50 of the nano calcium hydroxide is less than 600 nm. 90 less than 600 nm. The adsorption-induced transport type hydraulic lime suspension is used for repairing the earthen site. The preparation method of the adsorption-induced transport type hydraulic lime suspension comprises the following steps: The sodium hydroxide is mixed with the spherical micro-nano-pozzolanic material to prepare a high pozzolanic activity solution by a hydrothermal synthesis method. The high pozzolanic activity solution, the remaining water and the nanometer calcium hydroxide are mixed, and the dispersant is added and stirred uniformly to obtain the adsorption-induced transport type hydraulic lime suspension.

2. The adsorptive induced transport type hydraulic lime suspension according to claim 1, characterized in that, According to the mass fraction, the spherical micro-nano-pozzolanic material comprises superfine fly ash 15-25 parts, silica fume 5-10 parts and nanometer silicon dioxide 1-3 parts.

3. The adsorptive induced transport type hydraulic lime suspension according to claim 1, characterized in that, According to the mass fraction, the dispersant comprises polysorbate 0.2-0.3 parts, glycerol 0.1-0.2 parts and water reducing agent 0.1-0.3 parts.

4. A method for producing the adsorptive induced transport type hydraulic lime suspension according to any one of claims 1 to 3, characterized in that, The preparation method of the adsorption-induced transport type hydraulic lime suspension comprises the following steps: The sodium hydroxide is mixed with the spherical micro-nano-pozzolanic material to prepare a high pozzolanic activity solution by a hydrothermal synthesis method. The high pozzolanic activity solution, the remaining water and the nanometer calcium hydroxide are mixed, and the dispersant is added and stirred uniformly to obtain the adsorption-induced transport type hydraulic lime suspension.

5. The method for producing an adsorption-induced transport type hydraulic lime suspension according to claim 4, characterized in that, The mass ratio of the sodium hydroxide to water is (3-5) :

20. In the hydrothermal synthesis method, the temperature of the hydrothermal synthesis is 90℃, and the time is 15-25 min.

6. The adsorption-induced transport type hydraulic lime suspension of any one of claims 1-3 is used for repairing the earthen site.

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