CN114656284B

CN114656284B - Nanoclay calcium hydroxide composite material for repairing and reinforcing as well as preparation and application thereof

Info

Publication number: CN114656284B
Application number: CN202210303272.3A
Authority: CN
Inventors: 张宏斌; 王金华; 闫宏彬; 王奕; 高佩华; 樊尧
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2022-03-24
Filing date: 2022-03-24
Publication date: 2023-05-02
Anticipated expiration: 2042-03-24
Also published as: CN114656284A

Abstract

The invention relates to a nano clay calcium hydroxide composite material for repairing and reinforcing, and a preparation method and application thereof, wherein the nano clay calcium hydroxide composite material is prepared by controlling the ionization degree of calcium ions and hydroxide ions in a nano clay dispersion liquid and the supersaturation degree of a solution, so that nano calcium hydroxide grows on a nano clay sheet in situ; the composite material is uniformly dispersed in alcohol or alcohol-water composite liquid, and is applied to functional protection such as restoration and reinforcement of stone relic rock mass and surface. Compared with the prior art, the preparation method of the nano clay calcium hydroxide repairing and reinforcing material is simple, the composite proportion of clay and calcium hydroxide is adjustable and controllable, the size is uniform, the prepared protective liquid is high in dispersion, good in fluidity and strong in permeability, has good compatibility with rocks, is free of soluble salt, is suitable in rigidity and hardness, is suitable in curing time, and has high applicability, safety and durability and no derivative damage to protecting stone cultural relics.

Description

Nanoclay calcium hydroxide composite material for repairing and reinforcing as well as preparation and application thereof

Technical Field

The invention belongs to the technical field of stone relics such as grotto temple and the like, and relates to a nano-clay calcium hydroxide composite material for repairing and reinforcing, and preparation and application thereof.

Background

Immovable relics such as grottoes temple are usually exposed to various environments and conditions which are easy to cause weathering and degradation, including physical erosion, chemical corrosion and biological pollution, and even harmful materials used in the past repairing intervention, so that breakage phenomena such as peeling, weathering, cracking and discoloration are easy to occur. In order to enhance the durability of these relics, protection personnel have made great efforts in developing protective materials. Aiming at the diseases such as spalling, weathering and cracking of stone relics, the stone relic repairing and reinforcing material is a material which is widely researched at present, and mainly aims to repair damaged parts, reinforce cracking parts of a rock body and avoid further cracking and warping of the rock to influence the safety of the relics.

The repairing and reinforcing materials are mainly divided into two major categories, namely organic materials and inorganic materials. In addition to natural organic materials, the most widely used at present are epoxy resins, organic silicon materials, organic fluorine materials and the like. Organic protective materials are widely applied to early cultural relic protection due to good short-term performance, low price and the like, but the organic materials have obvious defects after application, have low compatibility with rock in the aspects of physical chemistry, mechanics and the like, are easy to cause salt to nucleate and grow at an interface, and most of the organic materials are easy to age, degrade, change color and lose mechanical strength. Inorganic materials have excellent compatibility with rocks and have been widely focused and used in the literature protection industry in recent years.

The main inorganic protective materials for repairing and reinforcing stone relics are cement, lime, geopolymer and the like. However, the inorganic material also needs to pay attention to the safety, adaptability, durability, no derivative damage and the like of the material, the traditional cement material used in the early grotto temple repairing and reinforcing engineering is easy to cause salt damage, high in strength and rigidity, and the traditional lime material has better compatibility with rocks, but also has the problems of low solubility, poor permeability, slow maintenance, low strength, easy shrinkage and the like.

Disclosure of Invention

The invention aims to provide a nano clay calcium hydroxide composite material for repairing and reinforcing, and preparation and application thereof, which are used for repairing, reinforcing and protecting stone relics and rock bodies and surfaces of stone caverns and temples.

The aim of the invention can be achieved by the following technical scheme:

one of the technical schemes of the invention provides a nano-clay calcium hydroxide composite material for repairing and reinforcing, which comprises nano-clay sheets and nano-calcium hydroxide grown on the nano-clay sheets in situ.

The second technical scheme of the invention provides a preparation method of the nano-clay calcium hydroxide composite material for repairing and reinforcing, and the nano-calcium hydroxide in situ growth on the nano-clay sheet is realized by regulating and controlling the ionization degree of calcium ions and hydroxyl ions in the nano-clay dispersion liquid and the supersaturation degree of the solution. Specifically, the ionization degree of calcium ions and hydroxyl ions, the supersaturation degree of the solution and the like are regulated and controlled by introducing weak electrolyte.

Further, specifically, the method comprises the following steps:

dispersing the nano clay in water or alcohol-water composite liquid to obtain nano clay dispersion liquid, and gradually adding calcium salt providing calcium ions and alkali or salt providing hydroxide ions to realize nano calcium hydroxide growth on the surface of the nano clay. At least one of the calcium-containing salt providing calcium ions or the base or salt providing hydroxide ions needs to be a weak electrolyte, depending on the requirements for the ionization degree control of the solution calcium ions and hydroxide ions. Such as: calcium acetate is the weak electrolyte of calcium, calcium chloride is the strong electrolyte of calcium, sodium hydroxide is the strong electrolyte of hydroxide, ammonia water is the weak electrolyte of hydroxide, a combination of calcium acetate and sodium hydroxide (weak-strong), calcium chloride and ammonia water (strong-weak), or calcium acetate and ammonia water (weak-weak) is needed, but a combination of calcium chloride and sodium hydroxide (strong-strong), which are both strong electrolytes, cannot be used. And the supersaturation degree control requirement for the calcium ions and the hydroxyl ions of the solution can be based on the difference of the adopted weak-strong, strong-weak and weak-weak combinations, and the amounts of various substances added into the electrolyte can be further reasonably regulated to reasonably control the amounts of the calcium ions and the hydroxyl ions in the solution, so as to control the supersaturation degree.

Further, the concentration of the nanoclay in the nanoclay dispersion is 0.5 to 100g/L, and the concentration of the calcium salt, hydroxide ion-providing base or salt is 0.3 to 200g/L, respectively and independently. The alcohol solvent used in the dispersion is any one of methanol, ethanol, n-propanol, and isopropanol.

Further, the molar ratio of the calcium-containing salt, the hydroxide ion-providing base or the salt is 10 ^-3 -10 ³ ：1。

Further, the calcium-containing salt is at least one selected from calcium acetate, calcium oxalate, calcium phosphate, calcium iodate and calcium molybdate.

Further, the base or salt providing hydroxide ions is selected from at least one of ammonia water, urea, bicarbonate, hydrogen phosphate, sulfite.

Further, the nanoclay is at least one of nano metakaolin, nano hectorite, nano montmorillonite, nano kaolin, nano sepiolite and attapulgite.

Furthermore, at least one dimension in the three-dimensional space of the composite material is kept at a nano-size (1-100 nm) or the composite material is taken as a basic unit to form a material.

The third technical scheme of the invention provides an application of the nano clay calcium hydroxide composite material for repairing and reinforcing, and the composite material is used for repairing and reinforcing stone relic rock mass.

Further, in specific use, the composite material is uniformly dispersed in alcohol or alcohol-water composite liquid to obtain the repairing and reinforcing liquid.

Furthermore, when the stone relics are protected, the stone relics are treated by adopting modes of repairing and reinforcing liquid spray coating, drip, injection, infiltration and the like;

the concentration of the repairing and reinforcing liquid is 1-300g/L, the application humidity of the repairing and reinforcing liquid is lower than 60%, and the application temperature is 0-50 ℃.

Compared with the prior art, the invention has the following advantages:

(1) The nano clay calcium hydroxide repairing and reinforcing material has the independent characteristics and the composite characteristics of nano clay and nano calcium hydroxide, and the composite proportion of clay and calcium hydroxide is adjustable and controllable, the size is uniform, the reactivity is high, the hardening is fast, and the cementing structure is stable.

(2) The preparation method of the nano clay calcium hydroxide repairing and reinforcing material is simple, easy, quick and efficient, and can lay a good foundation for large-scale application; is more environment-friendly and safer, has less harm to rock mass, operators and environment, and has good biocompatibility, no toxicity and no irritation.

(3) The repair and reinforcement protective liquid prepared by the nano clay calcium hydroxide repair and reinforcement material has the characteristics of high dispersion, good fluidity, strong permeability, good rock compatibility, no soluble salt, proper rigidity and hardness, proper maintenance time and the like

(4) The nano clay calcium hydroxide repairing and reinforcing material is used for protecting stone relics mainly in sandstone grotto temple, has more uniform effect and high retention rate, and has the characteristics of high applicability, safety, durability and no derivative damage.

Drawings

FIG. 1 is a TEM image of a nanoclay calcium hydroxide repair reinforcement material of the present invention;

FIG. 2 is a photograph showing that the nano clay calcium hydroxide repairing and reinforcing material is highly dispersed in an alcohol-water mixed solution and shows a tyndall phenomenon in the invention;

FIG. 3 is an SEM photograph showing the effect of the nanoclay calcium hydroxide repair reinforcing material of the present invention filling microcracks and covering the membrane.

Detailed Description

The invention will now be described in detail with reference to the drawings and specific examples. The present embodiment is implemented on the premise of the technical scheme of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following examples.

In the following examples, nano hectorite and nano montmorillonite were purchased from Nanocor, nano hectorite was RD or RDS, nano montmorillonite was PGW, nano kaolin, attapulgite, sepiolite were purchased from Henan Henry New Material Co.

The remainder, unless specifically stated, is indicative of a conventional commercially available feedstock or conventional processing technique in the art.

Example 1

(1) The nano metakaolin is adopted to be roasted for 5 hours at 750 ℃ to obtain the nano metakaolin. The obtained metakaolin is immersed into deionized water containing 5wt% of isopropanol to be uniformly dispersed, and the mass ratio of the solution to the nano metakaolin is 10:1. Then, to 100ml of the nano metakaolin dispersion liquid, 30ml of 0.05M calcium acetate and 30ml of 0.10M sodium hydroxide aqueous solution were added in sequence, and the mixture was reacted at room temperature for 10 minutes. Filtering and separating to obtain a solid product, washing with deionized water for three times, and drying at 100 ℃ to obtain the nano metakaolin calcium hydroxide composite material powder.

(2) The repairing protection solution is prepared by dispersing 10wt% of the repairing protection solution in isopropanol. The sandstone block was treated 3 times with a shower method at 25℃and 45% humidity for 28 days.

(3) After treatment, the penetration depth is 6.8mm, the solidification degree is more than 99%, the porosity of the sandstone block is reduced by 8.5%, the saturation deformation is less than 0.5%, the uniaxial compressive strength is improved by 9.3%, and the chromatic aberration is less than 0.2%.

Example 2

(1) The nano metakaolin is adopted to be roasted for 5 hours at 750 ℃ to obtain the nano metakaolin. The obtained metakaolin is immersed into deionized water containing 5wt% of n-propanol to be uniformly dispersed, and the mass ratio of the solution to the nano metakaolin is 20:1. Then, to 100ml of the nano metakaolin dispersion liquid, 30ml of 0.08M calcium acetate and 30ml of 0.20M aqueous ammonia solution were added in sequence, and the mixture was reacted at room temperature for 10 minutes. Filtering and separating to obtain a solid product, washing with deionized water for three times, and drying at 100 ℃ to obtain the nano metakaolin calcium hydroxide composite material powder.

(2) The repairing protection solution is prepared by dispersing the repairing protection solution in isopropanol with the mass ratio of 5 percent. The sandstone block was treated 3 times with a shower method at 25℃and 45% humidity for 28 days.

(3) After treatment, the penetration depth is 16.8mm, the solidification degree is more than 99%, the porosity of the sandstone block is reduced by 11.5%, the saturation deformation is less than 0.5%, the uniaxial compressive strength is improved by 8.3%, and the chromatic aberration is less than 0.2%.

Example 3

(1) The nano metakaolin is adopted to be roasted for 5 hours at 750 ℃ to obtain the nano metakaolin. The obtained metakaolin is immersed into deionized water to be uniformly dispersed, and the mass ratio of the solution to the nano metakaolin is 30:1. Then, to 100ml of the nano metakaolin dispersion liquid, 30ml of 0.05 calcium iodate and 30ml of 0.15M sodium bicarbonate aqueous solution were added in sequence, and the mixture was reacted at room temperature for 10 minutes. Filtering and separating to obtain a solid product, washing with deionized water for three times, and drying at 100 ℃ to obtain the nano metakaolin calcium hydroxide composite material powder.

(3) After treatment, the penetration depth is 9.8mm, the solidification degree is more than 99%, the porosity of the sandstone block is reduced by 11.5%, the saturation deformation is less than 0.5%, the uniaxial compressive strength is improved by 10.3%, and the chromatic aberration is less than 0.2%.

Example 4

(1) RD-type nano hectorite is immersed into deionized water containing 20wt% of ethanol for uniform dispersion, and the mass ratio of the solution to the nano hectorite is 25:1. Then, to 100ml of the nano hectorite dispersion, 30ml of 0.10M calcium oxalate solution and 30ml of 0.25M sodium hydroxide solution were added, followed by reaction at room temperature for 10 minutes. Filtering and separating to obtain a solid product of the composite material, washing with deionized water for three times, and drying at 100 ℃ to obtain nano hectorite calcium hydroxide composite material powder.

(2) Dispersing the mixture in ethanol with the mass ratio of 5wt% to prepare repair protection solution. The sandstone block is treated for 3 times by adopting an infiltration method under the conditions of 25 ℃ and 45% humidity, and is maintained for 28 days.

(3) After treatment, the penetration depth is 15.5mm, the solidification degree is more than 99%, the porosity of the sandstone block is reduced by 7.5%, the saturation deformation is less than 0.2%, the uniaxial compressive strength is improved by 17.3%, and the chromatic aberration is less than 0.2%.

Example 5

(1) Immersing RDS type nano hectorite into deionized water for uniform dispersion, wherein the mass ratio of the solution to the nano hectorite is 20:1. Then, to 100ml of the nano hectorite dispersion, 30ml of 0.06M calcium chloride and 30ml of 0.20M ammonia water were added in this order, and the mixture was reacted at room temperature for 10 minutes. Filtering and separating to obtain a solid product of the composite material, washing with deionized water for three times, and drying at 100 ℃ to obtain nano hectorite calcium hydroxide composite material powder.

(3) After treatment, the penetration depth is 11.5mm, the solidification degree is more than 99%, the porosity of the sandstone block is reduced by 10.5%, the saturation deformation is less than 0.3%, the uniaxial compressive strength is improved by 14.3%, and the chromatic aberration is less than 0.3%.

Example 6

(1) RD nano hectorite is immersed into deionized water containing 10wt% of isopropanol to be uniformly dispersed, and the mass ratio of the solution to the nano hectorite is 10:1. Then, to 100ml of the nano hectorite dispersion, 30ml of 0.10M calcium oxalate solution and 30ml of 0.25M sodium hydroxide solution were added, followed by reaction at room temperature for 10 minutes. Filtering and separating to obtain a solid product of the composite material, washing with deionized water for three times, and drying at 100 ℃ to obtain nano hectorite calcium hydroxide composite material powder.

(2) The repairing protection solution is prepared by dispersing the repairing protection solution in isopropanol with the mass ratio of 30 percent. The sandstone block is treated for 3 times by adopting an infiltration method under the conditions of 25 ℃ and 45% humidity, and is maintained for 28 days.

(3) After treatment, the penetration depth is 5.5mm, the solidification degree is more than 98%, the porosity of the sandstone block is reduced by 18.5%, the saturation deformation is less than 0.5%, the uniaxial compressive strength is improved by 12.3%, and the chromatic aberration is less than 0.5%.

Example 7:

in this example, the nanoclay used was nanoclay. The procedure is as in example 6.

Example 8:

in this example, the nanoclay used was nanokaolin. The procedure is as in example 6.

Example 9:

in this example, the nanoclay used was nano sepiolite. The procedure is as in example 6.

Example 10:

in this example, the nanoclay used was a nano-attapulgite. The procedure is as in example 6.

FIG. 1 is a TEM image of a nanoclay calcium hydroxide repair reinforcement material of example 1 of the present invention; it can be seen that: the nano clay calcium hydroxide repairing and reinforcing material prepared by the invention has a nano lamellar compound structure, the particle size is uniformly dispersed, and no obvious impurity phase exists.

FIG. 2 is a photograph showing the high dispersion of the reinforcing material for repairing nanoclay calcium hydroxide in an alcohol-water mixture and the phenomenon of tyndall in example 2 of the present invention; it can be seen that: the nano clay calcium hydroxide repairing and reinforcing material prepared by the invention can be highly dispersed in alcohol-water mixed solution, flocculates without agglomeration and can be stably stored for a long time.

FIG. 3 is an SEM photograph showing the effect of the nano clay calcium hydroxide repairing and reinforcing material filling microcracks and covering the microcracks to form a film in example 3 of the present invention; it can be seen that: the nano clay calcium hydroxide repairing and reinforcing material prepared by the invention can uniformly fill rock microcracks and can uniformly form a film on the surface.

Comparative example 1:

in comparison with example 1, the same is largely true except that no nano-metakaolin is added to the synthesis system. Because the nano clay component is not added as in the patent requirements, the obtained calcium hydroxide has larger particles, poor dispersibility and low reactivity. After the application of repairing and reinforcing the surface of the stone relic, the permeability is poor, small cracks cannot be filled in, and only the air hardening performance is low, the hardening speed is low, and the cementing performance is poor.

Comparative example 2:

much the same as in example 1, except that the nano-metakaolin was added after mixing the calcium acetate and sodium hydroxide. Since Ca (OH) is not in situ mediated at the nanoclay interface as in the patent claims ₂ The nano clay calcium hydroxide composite material grows, the two species are non-uniformly compounded, the phase separation is serious, and the material particles are large and the dispersibility is poor. After the application of repairing and reinforcing the surface of the stone relic, the stone relic has poor permeability, small cracks can not be filled, the hydraulic and pneumatic hardening reactivity is low, the hardening speed is low, and the cementing property is poor.

Comparative example 3:

most of the same as in example 1 except that the calcium acetate was changed to an equimolar amount of calcium chloride. Because weak electrolyte is not adopted and the concentration is regulated to control the activity and supersaturation, calcium hydroxide on the surface of the nano clay grows unevenly, particles are larger, the composition is uneven, and independent calcium hydroxide is generated in the solution. After the application of repairing and reinforcing the surface of the stone relic, the stone relic has poor permeability, small cracks are difficult to pour in, and the stone relic is uneven after being poured in, has lower reactivity, lower hardening speed and poor cementing property.

Comparative example 4:

most of the same as in example 5 except that the ammonia was changed to equimolar amount of sodium hydroxide. Because weak electrolyte is not adopted and the concentration is regulated to control the activity and supersaturation, calcium hydroxide on the surface of the nano clay grows unevenly, particles are larger, the composition is uneven, and independent calcium hydroxide is generated in the solution. After the application of repairing and reinforcing the surface of the stone relic, the stone relic has poor permeability, small cracks are difficult to pour in, and the stone relic is uneven after being poured in, has lower reactivity, lower hardening speed and poor cementing property.

Comparative example 5:

most of the same as in example 1, except that curing was performed under a humidity of 75%. Due to the fact that the curing humidity is too high, the composite material cannot be well poured into stone relics, the permeability is low, the pouring is uneven, the retention rate is low, and the surface repairing and reinforcing effects of the stone relics are poor.

Example 11:

in comparison with example 1, the vast majority are identical, except in this example: the concentration of the nano metakaolin in the nano metakaolin dispersion liquid is 0.5-100g/L, the concentration of the calcium acetate is 0.3-200g/L, and the concentration of the sodium hydroxide is 0.3-200g/L.

Example 12:

in comparison with example 1, the vast majority are identical, except in this example: the concentration of the nano metakaolin in the nano metakaolin dispersion liquid is 0.5g/L, the concentration of the calcium acetate is 0.3g/L, and the concentration of the sodium hydroxide is 0.3g/L.

Example 13:

in comparison with example 1, the vast majority are identical, except in this example: the concentration of the nano metakaolin in the nano metakaolin dispersion liquid is 100g/L, the concentration of the calcium acetate is 200g/L, and the concentration of the sodium hydroxide is 200g/L.

Example 14:

in comparison with example 1, the vast majority are identical, except in this example: the concentration of the nano metakaolin in the nano metakaolin dispersion liquid is 50g/L, the concentration of the calcium acetate is 20g/L, and the concentration of the sodium hydroxide is 30g/L.

Example 15:

in comparison with example 1, the vast majority are identical, except in this example: the concentration of the nano metakaolin in the nano metakaolin dispersion liquid is 20g/L, the concentration of the calcium acetate is 10g/L, and the concentration of the sodium hydroxide is 5g/L.

The previous description of the embodiments is provided to facilitate a person of ordinary skill in the art in order to make and use the present invention. It will be apparent to those skilled in the art that various modifications can be readily made to these embodiments and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present invention.

Claims

1. A nanoclay calcium hydroxide composite material for repair reinforcement comprising nanoclay platelets and nano calcium hydroxide grown in situ on the nanoclay platelets;

the composite material is prepared by the following steps:

dispersing the nano clay in water or alcohol-water composite liquid to obtain nano clay dispersion liquid, and gradually adding calcium salt providing calcium ions and alkali or salt providing hydroxide ions to realize nano calcium hydroxide growth on the surface of the nano clay;

at least one of the calcium-containing salt providing calcium ions or the base or salt providing hydroxide ions needs to be a weak electrolyte.

2. A method for preparing a reinforced nanoclay calcium hydroxide composite material as claimed in claim 1, wherein,

3. The method for preparing a reinforced nanoclay calcium hydroxide composite material according to claim 2, wherein the concentration of nanoclay in the nanoclay dispersion is 0.1 to 300g/L, and the concentration of alkali or salt containing calcium salt, providing hydroxide ions is 0.1 to 300g/L, respectively.

4. The method for preparing a reinforced nanoclay calcium hydroxide composite material according to claim 2, wherein the molar ratio of calcium salt, hydroxide ion providing base or salt is 10 ^-3 -10 ³ ：1。

5. The method for preparing the reinforced nano-clay calcium hydroxide composite material according to claim 2, wherein the nano-clay is at least one of nano-metakaolin, nano-hectorite, nano-montmorillonite, nano-kaolin, nano-sepiolite and attapulgite.

6. The method for preparing a reinforced nanoclay calcium hydroxide composite material according to claim 2, wherein the calcium-containing salt is at least one selected from the group consisting of calcium acetate, calcium oxalate, calcium phosphate, calcium iodate, and calcium molybdate;

the base or salt providing hydroxide ions is selected from at least one of ammonia water, urea, bicarbonate, hydrogen phosphate and sulfite.

7. The use of a nanoclay calcium hydroxide composite for repair reinforcement as claimed in claim 1, wherein the composite is used for repair reinforcement of stone relic rock mass.

8. The use of the nanoclay calcium hydroxide composite material for repair reinforcement according to claim 7, wherein the repair reinforcement is prepared by dispersing the composite material uniformly in an alcohol or alcohol-water composite solution.

9. The application of the nano clay calcium hydroxide composite material for repairing and reinforcing according to claim 8, wherein the stone relics are treated in a manner of repairing and reinforcing liquid spray coating, drip, injection or infiltration;