CN104163656A - Method for reinforcing carbonate rock stone historical relics - Google Patents

Abstract

A method for reinforcing carbonate rock cultural relics, comprising the following steps: (1) cleaning the rock surface with deionized water; (2) adjusting the pH to 3.8-4.4 with tartaric acid and ammonia water, and the tartaric acid concentration is 0.15 ~0.20mol·L ^-1 ammonium tartrate solution to treat the rock surface; (3) Then treat the stone surface with modified tetraethyl silicate sol; (4) Aging at room temperature for more than 7 days. The advantages of the present invention are: since silicon dioxide is produced by the hydrolysis of tetraethyl orthosilicate, it has good compatibility with the stone base and does not change the appearance, color and feel of the protected stone cultural relics; it makes the stone hydrophobic and compressive Strength, acid resistance, stain resistance are improved and increased.

Description

A method for strengthening carbonate rock-like stone cultural relics

technical field

The invention relates to a reinforcement method for loose calcium carbonate rock, which is mainly used for surface layer reinforcement of inferior calcium carbonate stone cultural relics.

Background technique

my country has a large number of precious cultural relics and historical relics, among which open-air stone relics occupy an important position, such as the Stone Carvings of the Six Dynasties, Leshan Giant Buddha, Yungang Grottoes, Dunhuang Grottoes, Longmen Grottoes, Nanxiangtang Grottoes, Dazu Rock Carvings, etc. These cultural relics are important historical resources and tourism resources. The open-air stone cultural relics are mainly divided into silicates and carbonates according to the rock composition. Silicate rocks include granite, glutenite, etc. Granite is hard, durable, and highly stable, such as Yungang Grottoes, most of which are carved on feldspar quartz sandstone, and its main component is SiO ₂ , followed by Al ₂ O ₃ ; the main component of sandy conglomerate is also SiO ₂ , but Most of the SiO ₂ in this kind of rock is very fine quartz particles of sedimentary facies, and the cement between the particles is easy to be destroyed, the hardness is not high, and it is easy to weather, such as Leshan Giant Buddha (soft siltstone), Dunhuang Mogao Grottoes, etc.; Carbonate rocks include limestone (mainly CaCO ₃ ) and dolomite (with a certain content of MgCO ₃ ), etc., whose stability is between granite and glutenite, such as the Stone Carvings of the Six Dynasties, Nanxiangtang Grottoes, and Longmen Grottoes wait. The stone carvings of the Six Dynasties belong to carbonate rocks, representing the highest level of stone carving art in the central and southern regions during the Wei, Jin, Southern and Northern Dynasties. They are art treasures comparable to the works of ancient Egypt, Babylon, India, Greece, Rome, and the Renaissance. They have a worldwide reputation. Influence. Due to chemical effects (acid rain, aerosols in the atmosphere, SO ₂ , NO _X and organic pollutants), physical effects (freezing and thawing, salt action), and the corrosion of acids secreted by organisms attached to stone cultural relics, stone carvings of the Six Dynasties etc. Destruction of carbonate stone cultural relics. In order to prevent the corrosion and deterioration of stone cultural relics from chemical, physical and biological effects, or to reinforce fragile, broken and collapsed stone, a layer of protective material is usually coated on the surface of the stone. Currently widely used protective materials are alkoxysilanes, such as ethyl orthosilicate. The siloxane polymer produced when this kind of protective material treats rocks can create a bridging effect between inorganic particles. Through the hydrolysis of alkoxy groups, the adjacent particles are linked together by siloxane chains to make the weak and loose Sandstone is reinforced and strengthened. The product of alkoxysilane reaction is similar to sandstone containing silicon compounds, and has good compatibility and affinity with sandstone, so it has good protection for sandstone. For the protection of carbonate rocks, due to the lack of affinity between alkoxysilane and carbonate rocks, chemical bonds cannot be formed between rocks and polymers, and the protection of carbonate rocks is not ideal, thus limiting the application of alkoxysilanes Strengthening of carbonate rocks. Ethyl orthosilicate is a typical representative of alkoxysilane, which has the advantages of low viscosity, can penetrate into the pores of stone, and interact with water vapor in the environment to form a stable gel with silicon-oxygen bonds. However, during the drying process of stone pores, due to the gas-liquid bending surface in the gel, the capillary force is different, resulting in cracks in the gel, so that it cannot effectively strengthen the stone, especially the deteriorated stone.

Contents of the invention

The invention proposes a crack-free preparation method of tetraethyl orthosilicate, and can be applied to carbonate stone cultural relics such as stone carvings of the Six Dynasties.

In order to achieve the above object, the present invention takes the following measures: first, the surface of the rock to be reinforced is cleaned with deionized water, then pretreated with ammonium tartrate solution, and then the stone cultural relics are treated with modified tetraethyl silicate sol, so that The micro-cracks of the loose rock are filled and the surface is covered with silica, thereby strengthening and protecting the loose calcium carbonate rock.

The present invention is achieved through the following technical solutions.

A method for reinforcing carbonate-like stony cultural relics comprises the following steps.

(1) Clean the rock surface with deionized water.

(2) Use tartaric acid and ammonia water to adjust the pH=3.8~4.4, the tartaric acid concentration is 0.15~0.20mol·L ^-1 ammonium tartrate solution, and treat the rock surface to form a calcium tartrate transition layer on the rock surface, so that the rock surface is covered with functional hydroxyl groups.

(3) Then the surface of the stone is treated with modified tetraethyl silicate sol, and a reinforced protective layer with silica as the main component is formed in the pores of the loose rock, and these protective layers are connected with calcium carbonate through hydroxyl groups.

(4) Aging at room temperature for more than 7 days.

Preparation of the modified tetraethyl orthosilicate sol described in step (3): firstly, mix ethyl orthosilicate and ethanol at room temperature, stir for 10 minutes, add deionized water, and sonicate for 10 minutes under stirring conditions, and then Add hydroxyl-terminated polydimethylsiloxane under vigorous stirring, and finally add surfactant n-octylamine under vigorous stirring, and control ethyl orthosilicate: ethanol: water: polydimethylsiloxane The molar ratio of alkane:n-octylamine is 1:16:10:0.04:0.002; the molecular weight of the polydimethylsiloxane with hydroxyl as the terminal group is Mn≈550.

In the preparation of the modified tetraethyl orthosilicate sol described in step (3) of the present invention, the ethanol can be replaced by isopropanol or acetone. Described surfactant n-octylamine can be replaced by dibutyltin dilaurate.

In the step (3) of the present invention, methods such as brushing and spraying can be used for the operation of treating the stone surface with tetraethyl silicate sol.

The advantages of the present invention are: since silicon dioxide is produced by the hydrolysis of tetraethyl orthosilicate, it has good compatibility with the stone base and does not change the appearance, color and feel of the protected stone cultural relics; it makes the stone hydrophobic and compressive strength , acid resistance, stain resistance are improved and enhanced.

Description of drawings

Fig. 1 is the graph that pH value of the present invention changes with time.

Fig. 2 is a graph showing the variation of Ca2 ⁺ concentration with time in the present invention.

Fig. 3 Schematic diagram of the acid resistance performance evaluation device.

Detailed ways

Below in conjunction with embodiment the invention is described in detail.

Example 1.

(1) Clean the rock surface with deionized water;

(2) Use tartaric acid and ammonia water to adjust the pH=3.8, and the tartaric acid concentration is 0.15mol·L ^-1 ammonium tartrate solution, and treat the rock surface to form a calcium tartrate transition layer on the rock surface, so that the rock surface is equipped with functional hydroxyl groups group;

(3) Then the surface of the stone is treated with modified tetraethyl silicate sol, and a reinforced protective layer with silica as the main component is formed in the pores of the loose rock, and these protective layers are connected with calcium carbonate through hydroxyl groups;

(4) Aging at room temperature for 30 days.

Preparation of the modified tetraethyl orthosilicate sol described in step (3): at room temperature, first mix ethyl orthosilicate and ethanol, stir for 10 minutes, add deionized water, and then ultrasonicate for 10 minutes under stirring conditions, and then Add polydimethylsiloxane with hydroxyl as the end group under vigorous stirring, and finally add surfactant n-octylamine under vigorous stirring, and control the concentration of ethyl orthosilicate: ethanol: water: polydimethylsiloxane when adding dropwise. : The molar ratio of n-octylamine is 1:16:10:0.04:0.002; the molecular weight of the polydimethylsiloxane with hydroxyl as the terminal group is Mn≈550.

Acid resistance, the stone treated with modified tetraethyl orthosilicate sol, under the leaching of sulfuric acid solution with pH=4.0, the measured pH and Ca ²⁺ are smaller than the untreated stone, which is comparable to the commercial material stone protective material library Sol (Coesol) is comparable (Figure 1).

Evaluation method of anti-acid performance.

The experimental device (Fig. 3) consists of five parts: magnetic drive circulation pump, flow meter, liquid storage tank, liquid storage beaker and leaching pipe. During the experiment, the acid solution was circulated through a circulating pump, and the stone samples were continuously leached for 8 hours. The flow rate of the solution is controlled at 6mL·min ^-1 , and the leached stone is 50 mm in length, 50 mm in width, and 10 mm in thickness. (content is 97%), and the secondary components are oxides of silicon, aluminum and iron.

In order to visually characterize the reinforcement effect, 10g (80 mesh sieved) stone powder was mixed with 2mL water, compacted in a mold with a diameter of 3.2cm at 20MPa, and left naturally at room temperature for a week. The obtained sample was used as an imitation sample of loose rock. Slowly permeate 2mL of modified tetraethyl silicate sol on the surface of the imitation sample, and measure the reinforcement strength after standing naturally at room temperature for one month. The measured compressive strength increases from 77.4MPa to 126.2MPa, which is about 163% higher than that before no reinforcement. The measured surface hardness increased from 60HD to 84HD (Table 1).

Example 2.

(1) Clean the rock surface with deionized water.

(2) Use tartaric acid and ammonia water to adjust the pH=4.0, and the tartaric acid concentration is 0.17mol·L ^-1 ammonium tartrate solution, and treat the rock surface to form a calcium tartrate transition layer on the rock surface, so that the rock surface is equipped with functional hydroxyl groups group.

(3) Then the surface of the stone is treated with modified tetraethyl silicate sol, and a reinforced protective layer with silica as the main component is formed in the pores of the loose rock, and these protective layers are connected with calcium carbonate through hydroxyl groups.

(4) Aging at room temperature for 30 days.

Preparation of the modified tetraethyl orthosilicate sol described in step (3): firstly, mix ethyl orthosilicate and isopropanol, stir for 10 minutes, add deionized water, and then ultrasonicate for 10 minutes while stirring, then vigorously Add polydimethylsiloxane with hydroxyl as the terminal group under stirring, and finally add surfactant n-octylamine under vigorous stirring, and control ethyl orthosilicate: isopropanol: water: polydimethylsiloxane The molar ratio of alkane:n-octylamine is 1:16:10:0.04:0.002; the molecular weight of the polydimethylsiloxane with hydroxyl as the terminal group is Mn≈550.

The results showed that the compressive strength and surface hardness of the penetration-strengthened imitation samples were lower than that of Example 1 (Table 1).

Example 3.

(1) Clean the rock surface with deionized water.

(2) Use tartaric acid and ammonia water to adjust the pH=4.0, and the tartaric acid concentration is 0.17mol·L ^-1 ammonium tartrate solution, and treat the rock surface to form a calcium tartrate transition layer on the rock surface, so that the rock surface is equipped with functional hydroxyl groups group.

(3) Then the surface of the stone is treated with modified tetraethyl silicate sol, and a reinforced protective layer with silica as the main component is formed in the pores of the loose rock, and these protective layers are connected with calcium carbonate through hydroxyl groups.

(4) Aging at room temperature for 30 days.

Preparation of the modified tetraethyl orthosilicate sol described in step (3): firstly mix ethyl orthosilicate and acetone, stir for 10 minutes, add deionized water, and then ultrasonicate for 10 minutes while stirring, and then vigorously stir Add the polydimethylsiloxane with hydroxyl as the terminal group, and finally add the surfactant n-octylamine under vigorous stirring, and control the molar ratio of ethyl orthosilicate: acetone: polydimethylsiloxane: n-octylamine when dropping The ratio is 1:16:10:0.04:0.002; the molecular weight of the polydimethylsiloxane with hydroxyl as the terminal group is Mn≈550.

The results showed that the compressive strength and surface hardness of the penetration-strengthened imitation samples were lower than that of Example 1 (Table 1).

Example 4.

(1) Clean the rock surface with deionized water.

(2) Use tartaric acid and ammonia water to adjust the pH=4.2, and the tartaric acid concentration is 0.18mol·L ^-1 ammonium tartrate solution, and treat the rock surface to form a calcium tartrate transition layer on the rock surface, so that the rock surface is equipped with functional hydroxyl groups group.

(3) Then the surface of the stone is treated with modified tetraethyl silicate sol, and a reinforced protective layer with silica as the main component is formed in the pores of the loose rock, and these protective layers are connected with calcium carbonate through hydroxyl groups.

(4) Aging for 7 days at room temperature.

Preparation of the modified tetraethyl orthosilicate sol described in step (3): first, mix ethyl orthosilicate and ethanol, stir for 10 minutes, add deionized water, and then ultrasonicate for 10 minutes while stirring, and then vigorously stir Add polydimethylsiloxane with hydroxyl as the end group, and finally add dibutyltin dilaurate under vigorous stirring, and control ethyl orthosilicate: ethanol: water: polydimethylsiloxane: dilauric acid The molar ratio of dibutyltin is 1:16:10:0.04:0.002; the molecular weight of the polydimethylsiloxane with hydroxyl as terminal group is Mn≈550.

The results showed that the compressive strength and surface hardness of the penetration-strengthened imitation samples were lower than that of Example 1 (Table 1).

the

Table 1 Changes in compressive strength and hardness of stone treated with modified tetraethylorthosilicate sol

Claims (3)

1. reinforce a method for carbonate rock stone cultural artifact, it is characterized in that comprising the following steps:

(1) with deionized water, rock surface is cleaned up;

(2) with tartrate and ammoniacal liquor furnishing pH=3.8 ~ 4.4, tartaric acid concentration is 0.15 ~ 0.20molL ^-1tartrate ammonia solution, process rock surface;

(3) then process stone surface with the tetraethoxy colloidal sol of modification;

(4) aging more than 7 days under normal temperature;

The tetraethoxy colloidal sol preparation of the modification described in step (3): first under normal temperature, tetraethoxy and ethanol are mixed, stir 10 minutes, add deionized water, under agitation condition ultrasonic 10 minutes, then under vigorous stirring, adding hydroxyl is the polydimethylsiloxane of end group, under last vigorous stirring, adds tensio-active agent n-octyl amine, controls tetraethoxy: ethanol: water: polydimethylsiloxane: n-octyl amine mol ratio is 1:16:10:0.04:0.002 when dropping; Described hydroxyl is that the polydimethylsiloxane molecular weight of end group is Mn ≈ 550.

2. the method for reinforcing carbonate rock stone cultural artifact according to claim 1, is characterized in that the tetraethoxy colloidal sol preparation of the described modification of step (3), and described ethanol is substituted by Virahol or acetone; Described tensio-active agent n-octyl amine, is substituted by dibutyl tin laurate.

3. the method for reinforcing carbonate rock stone cultural artifact according to claim 1, is characterized in that the operation of the described tetraethoxy colloidal sol processing stone surface of step (3) is used brushing or spraying method.