A kind of adhesive material and protection method for sandstone class stone cultural relic body protection

Abstract

The application discloses a kind of for sandstone class stone historical relic body protection bonding material and protection method, it is related to sandstone class relic protection technical field, its technical key points are: including binder and grouting material, by mass ratio, binder is composed of the following components: 12-18% ultrafine portland cement, 0.5-1% sodium silicate, 8-12% water, 70-76% hydraulic lime;Grouting material is composed of the following components: 97-98% epoxy resin, 2-3% metakaolin.The application improves the compressive strength, tensile strength and shear strength of sandstone historical relics by using bonding material for historical relic restoration, and further improves the weathering resistance and corrosion resistance of sandstone historical relics, which is of great significance for the protection and improvement of the safety performance of historical relics.

Description

Technical Field

[0001] This invention relates to the field of sandstone cultural relic protection technology, specifically to an adhesive material and protection method for the protection of sandstone cultural relics. Background Technology

[0002] Over the past millennium, under the influence of long-term natural stress, sandstone artifacts have suffered from various forms of damage, including hollowing, flaking, and cracking. The structural planes controlling the stability of the rock mass all exhibit a certain degree of openness, and sandstone itself has poor resistance to weathering, especially open bedding planes. As weathering damage gradually increases, the tensile strength of the bedding planes in the weathered rock mass easily reaches its limit. Under conditions such as heavy rain and earthquakes, instability and fragmentation can occur, posing a significant threat to the safety of the artifacts and visitors. Therefore, necessary measures must be taken for prevention and treatment, hence the following invention research. The plan is to effectively solve the problems of weathering and cracking in sandstone artifacts by using this adhesive material for protective measures.

[0003] Therefore, this patent application is filed. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems and provide an adhesive material for the protection of sandstone artifacts. It is applicable to rock blocks with different thicknesses and crack sizes. The adhesive material provided by this invention has both adhesiveness and fluidity. It can not only fill small gaps, but also has strong adhesiveness, which can firmly bond sandstone artifacts and prevent them from falling off.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] An adhesive material for the protection of sandstone cultural relics includes an adhesive and a grout. By mass ratio, the adhesive is composed of the following components: 12-18% ultrafine silicate cement, 0.5-1% water glass, 8-12% water, and 70-76% hydraulic lime.

[0007] The principle of this invention: The main component of the adhesive is hydraulic lime. The hardening of hydraulic lime is divided into two stages. The first stage is the hydraulic stage, in which hydraulic lime is mixed with water for initial hardening. Following this, an air-hardening process gradually completes after the hydraulic hardening, which takes several months. Therefore, the adhesive provided in this application gradually increases in hardness during the restoration of cultural relics, meaning the weathering resistance of the relics also gradually improves. The hardening of the ultrafine silicate cement is divided into four stages: initial reaction period, induction period, setting period, and hardening period. During the hardening period, as the hydration products increase, the network structure formed by crystals and gels gradually becomes denser, and the capillary pores between particles gradually decrease, causing the slurry strength to continuously develop. When hydraulic lime and ultrafine silicate cement are mixed and used, they harden under uniform mixing conditions, enhancing adhesion, thus enabling the adhesive to bond sandstone-like cultural relics together. The adhesive fully penetrates and solidifies on the surface of the stone artifact. Through fine adjustments to the proportions of each component, the most suitable material is formulated based on the size of the rock block and different types of damage, combined with laboratory tests, to achieve the best bonding effect in terms of shear resistance, compressive strength, and tensile strength.

[0008] Preferably, the grouting material, by weight ratio, consists of the following components: 97-98% epoxy resin and 2-3% metakaolin. The epoxy resin-based grouting adhesive utilizes the advantages of epoxy resin, such as easy curing, strong adhesion, and low shrinkage. A small amount of water glass is added to moderately enhance its tensile strength, enabling high-strength bonding of larger rock blocks. In practical applications, for bonding large rock blocks, the surface should be cleaned, free of dust and impurities, and the material should be applied evenly and repeatedly until firmly bonded. For thicker rock blocks, multiple applications are necessary to ensure a strong bond. For smaller blocks, apply in small amounts multiple times carefully, avoiding application that could damage the rock.

[0009] More preferably, the epoxy value of the epoxy resin is 0.25-0.45. The higher the epoxy value, the lower the viscosity and the better the flowability. Selecting an epoxy value of 0.25-0.45 can ensure viscosity that meets the bonding requirements of larger rock blocks, so that the tensile strength of the bonded rock blocks is close to the tensile strength of the original rock.

[0010] This invention also relates to a construction process for an adhesive material used for the preservation of sandstone artifacts, comprising the following steps:

[0011] S1. Remove sand and dust from the cracks;

[0012] Preferably, the sand and dust in the fissures are treated by using an air compressor at a pressure of 0.2-0.5 MPa. Excessive pressure will damage the fissures and blocks, harming the artifact itself; insufficient pressure will not achieve the desired cleaning effect. Air is supplied until no excess impurities, dust, or weathering products remain in the fissures. This facilitates better contact and adhesion between the adhesive and the rock mass, achieving a thorough reinforcement effect.

[0013] S2. Bury grouting pipes in the cracks;

[0014] Preferably, the spacing between grouting pipes is 0.5-1m, the pipe diameter matches the opening gap of the crack, and the burial depth is 0.2-0.4m. This step is based on the principle of minimal intervention in cultural relics and has been improved upon through thorough testing. Otherwise, it will damage the surface and interior of the cultural relic. If the internal compressive stress is too high, it will cause brittle fracture and tensile cracks. Therefore, the spacing should not be too close, and the depth should not be too deep.

[0015] S3. Sealing: Use mortar to seal the crack opening. River mud from the site can be used as the mortar. Seal the crack opening from bottom to top to ensure that the mortar adheres tightly to the rock mass.

[0016] S4. Gas test: Gas is introduced into the grouting pipe to check the sealing effect of the cracks and to repair any leaks.

[0017] Preferably, the pressure of the gas introduced into the grouting pipe is 0.15-0.2 MPa. Excessive gas pressure will cause pipe blockage and accelerate condensation.

[0018] S5. Grout preparation: Prepare the appropriate grouting material and adhesive material according to the size of the crack and the thickness of the rock block.

[0019] S6. Grouting: Grout the prepared grout from bottom to top according to the pre-embedded grouting pipe; for the deepest small cracks that cannot be grouted by the grouting pipe, grout is injected by a syringe or by drilling small holes.

[0020] Preferably, the grout injection pressure is 0.15-0.2 MPa. Excessive pressure will cause damage to the substrate, while insufficient pressure will significantly reduce the bonding effect.

[0021] S7. Sealing: Use the sealing material prepared in S5 to seal the surface cracks and grouting pipes, and then use rock powder, mineral pigments and repair mortar to age the surface.

[0022] Compared with existing technologies, the beneficial effects of this solution are:

[0023] 1. The adhesive material provided by this invention includes grout and adhesive. The grout is suitable for repairing rock masses with cracks greater than 5mm. The internal friction angle of sandstone repaired by the grout can be restored to 98.79% of the original internal friction angle, and the cohesion can be restored to 98.01% of the original cohesion. The adhesive is suitable for repairing rock masses with cracks less than 5mm. Although epoxy resin has high bonding strength, its high expansion rate makes it unsuitable for repairing fragile small rock blocks. Rock blocks with small cracks and thin thickness cannot withstand the stress brought by the expansion of epoxy resin, and may even cause damage to the rock blocks.

[0024] 2. The construction process of the adhesive material provided by this invention is convenient to operate and is generally applicable to the restoration of sandstone cultural relics. Different construction methods can be flexibly selected according to different crack widths and rock mass delamination thicknesses.

[0025] 3. The adhesive material provided by the present invention can adjust its fluidity according to the ratio, which can make the bonding speed of sandstone rock mass faster, and has the characteristics of convenient curing, strong adhesion, and low shrinkage. It can also moderately enhance its tensile strength and aging resistance. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the sample preparation process in the experiment of this invention;

[0027] Figure 2 This is a schematic diagram of the direct shear specimens repaired with different adhesive materials in the experiments of this invention;

[0028] Figure 3 This is a schematic diagram of the splitting specimens repaired with different adhesive materials in the experiments of this invention;

[0029] Figure 4 This invention relates to the shear failure modes of straight-shear specimens repaired with different adhesive materials under different normal stresses during the experiment.

[0030] Figure 5 These are the shear failure modes of the straight shear specimens under different normal stresses in the experiments of this invention;

[0031] Figure 6 This describes the shear failure state of epoxy resin bonded direct shear specimens under different normal stresses in the experiments of this invention.

[0032] Figure 7 This is the shear strength envelope of the straight shear specimens repaired with different adhesive materials in the experiment of this invention;

[0033] Figure 8 These are the tensile failure modes of split specimens repaired with different adhesive materials in the experiments of this invention.

[0034] Figure 9This is a graph showing the change of vertical pressure and time experienced by the splitting specimen during the tensile test in this invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be described in further detail below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0037] Example 1

[0038] An adhesive material for the protection of sandstone cultural relics is prepared by the following method: take 17% ultrafine cement, 1% water glass, 70% hydraulic lime, and 12% water, mix the raw materials to obtain a grayish-white liquid adhesive material.

[0039] The adhesive material prepared in this embodiment is suitable for repairing sheet-like rock blocks with a thickness of 1mm-5mm, which are treated with pinhole injection.

[0040] Example 2

[0041] An adhesive material for the preservation of sandstone artifacts, comprising a grout for grouting and a sealing agent, is prepared by the following method:

[0042] Preparation of grout: Mix 97% epoxy resin and 3% metakaolin evenly to obtain grout.

[0043] Preparation of adhesive: Mix 15% ultrafine cement, 1% water glass, 10% water and 74% hydrated lime evenly to obtain adhesive.

[0044] The adhesive material prepared in this embodiment is suitable for thicknesses of 5 mm or more and areas of 0.5 m². 2 The above rock block repairs.

[0045] Example 3

[0046] An adhesive material for the protection of sandstone cultural relics is prepared by the following method: 76% hydraulic lime, 12% ultrafine cement, 1% water glass and 11% water are mixed evenly to obtain the adhesive material.

[0047] The adhesive material prepared in this embodiment is suitable for rock blocks with a thickness of less than 1 mm, which are injected by drilling small holes.

[0048] Example 4

[0049] A construction process for an adhesive material used for the preservation of sandstone artifacts includes the following steps:

[0050] S1. Remove sand and dust from the cracks; treat the sand and dust in the cracks by blowing air with an air compressor at a pressure of 0.5MPa.

[0051] S2. Bury grouting pipes in the fissures; the spacing between grouting pipes is 0.7m, the pipe diameter matches the opening of the fissure, and the burial depth is 0.3m.

[0052] S3. Sealing: Use mortar to seal the crack opening. The mortar is made of cohesive soil and hydrated lime. Seal the crack opening from bottom to top to ensure that the mortar adheres tightly to the rock mass.

[0053] S4. Gas test: Gas is introduced into the grouting pipe to check the sealing effect of the cracks, and leaks are repaired. The pressure of the gas introduced into the grouting pipe is 0.2 MPa. Excessive gas pressure will cause pipe blockage and accelerate condensation.

[0054] S5. Grout preparation: Prepare grout corresponding to the bonding material according to the size of the crack and the thickness of the rock block. Different bonding materials are used for wide and narrow cracks, as shown in Examples 1-3.

[0055] S6. Grouting: The grout prepared in S5 is injected from bottom to top through the pre-embedded grouting pipes; the deepest small cracks that cannot be reached by the grouting pipes are injected by injecting or drilling small holes; the grout injection pressure is 0.2 MPa.

[0056] S7. Sealing: Use adhesive to seal surface cracks and grouting pipes, and then use rock powder, mineral pigments and repair mortar to age the surface.

[0057] Comparative Example 1

[0058] An adhesive material for the protection of sandstone cultural relics is prepared by the following method: take 10% ultrafine cement, 1% water glass, 78% hydraulic lime, and 12% water, mix the raw materials to obtain a grayish-white liquid adhesive material.

[0059] Comparative Example 2

[0060] An adhesive material for the protection of sandstone cultural relics is prepared by the following method: take 20% ultrafine cement, 0.5% water glass, 69.5% hydrated lime, and 10% water, mix the raw materials to obtain a grayish-white liquid adhesive material.

[0061] Comparative Example 3

[0062] The difference between Comparative Example 3 and Example 2 is that the grouting material prepared is different. Specifically, 90% epoxy resin and 10% metakaolin are mixed evenly to obtain a grout.

[0063] Comparative Example 4

[0064] The difference between Comparative Example 4 and Comparative Example 3 is that the grouting material used is pure epoxy resin and does not contain metakaolin.

[0065] test

[0066] I. Sample Preparation: The intact sandstone used in the test was taken from the rock below the cliff face at the site of the cliff carvings. The rock was cut and prepared into cylindrical samples with a diameter of 5 cm and a height of 5 cm. The actual sample preparation process is detailed below. Figure 1 As shown, the cylindrical samples were then prepared into direct shear specimens and splitting specimens. The direct shear specimen preparation method was as follows: the sandstone cylindrical sample was cut along its central cross-section and bonded together using adhesive materials (grouting materials from Examples 1 and 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4). The splitting specimen preparation method was as follows: the sandstone cylindrical sample was cut radially and bonded together using adhesive materials (grouting materials from Examples 1 and 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4). The direct shear specimens were used for shear strength tests, and the splitting specimens were used for tensile strength tests. Direct shear specimens repaired with different adhesive materials are shown below. Figure 2 As shown, the splitting specimens repaired with different adhesive materials are as follows: Figure 3 As shown.

[0067] II. The basic physical properties of the sandstone used for the test samples are shown in Table 1.

[0068] Table 1 Basic physical properties of sandstone

[0069]

[0070] As shown in Table 1, the various indicators of the unrestored sandstone artifacts are as described above, including cohesion of 1.51 MPa, internal friction of 41.23°, average compressive strength of 20.58 MPa, and average tensile strength of 1.87 MPa.

[0071] 3. The diameter and height of the sample were measured using a vernier caliper, and its mass was measured using an electronic balance. The measurement results of the diameter and height of the repaired sample are shown in Table 2.

[0072] Table 2. Dimensions and mass of the repaired samples

[0073]

[0074]

[0075] As shown in Table 2, the test specimens were divided into shear specimens and splitting specimens, which were repaired using the adhesives of Examples 1-3 and Comparative Examples 1-4, respectively. The mass, height, and diameter of the repaired specimens are shown in the table above.

[0076] IV. Shear Strength Test

[0077] The mechanical properties of the samples were tested using a 1036PC universal testing machine, in accordance with the national standard "Test Method for Strength of Cement Mortar" (GB / T17671-1999).

[0078] 1. Test failure modes such as Figure 4 As shown.

[0079] The shear failure morphology of sandstone direct shear specimens of cultural relics restored with different adhesive materials under different normal stresses, from Figure 4 It can be seen that the samples basically failed along the interface between the bonding material and the sandstone, and the fracture surfaces were relatively smooth. All samples showed brittle failure. Due to the severe weathering of the sandstone and its low strength, longitudinal cracks appeared to varying degrees after the samples failed.

[0080] The sandstone samples bonded with epoxy resin exhibited a distinct rock-cracking sound upon failure, and a layer of sandstone adhered to the adhesive on the fractured surface, indicating that epoxy resin provides stronger adhesion. Figure 6 As shown. The remaining samples experienced significant horizontal and normal stresses upon failure, resulting in severe fragmentation. Some samples showed obvious frictional scratches on the shear surface, with the sandstone in the fracture surface reduced to powder, and adhesive fracture was also observed. Figure 5 As shown.

[0081] 2. Based on the peak normal force and peak tangential force obtained from the experiment, calculate the peak normal stress and peak tangential stress, as shown in Table 3; plot the shear strength failure envelope, as shown in Table 3. Figure 7 As shown. The data above were linearly fitted using the least squares method, and the internal friction angle of the specimen was obtained according to the Mohr-Coulomb strength criterion. The results are shown in Table 4, relating to the cohesive force c.

[0082] Table 3. Shear strength test results of sandstone specimens of cultural relics restored with different adhesive materials.

[0083]

[0084]

[0085]

[0086] As can be seen from Tables 3 and 4: (1) The internal friction angle of sandstone after epoxy resin bonding repair can be restored to 98.79% of the original internal friction angle, and the cohesion can be restored to 98.01% of the original cohesion. Combined with the construction process, the thicker the rock block, the higher the adhesiveness requirement of the bonding material. Therefore, the bonding material composed of 97% epoxy resin + 3% metakaolin is suitable for the repair of rock blocks with a thickness of more than 5mm; (2) For the two bonding materials, hydraulic lime + 5% ultrafine cement and hydraulic lime + 12% ultrafine cement, the internal friction angle and cohesion are relatively stable. The indicators recovered to 60.08%, 36.42% and 65.78%, 36.42% respectively. Considering the economic applicability of the formula, the adhesive of the formula is suitable for the repair of rock blocks with a thickness of less than 5mm; (3) In terms of the degree of shear strength recovery, the repair effect of the adhesive material from good to bad is as follows: Example 2, Example 1, Example 3, Comparative Example 1, Comparative Example 3, Comparative Example 4, Comparative Example 2. It can be seen that the shear strength recovery effect of the adhesive material provided by this scheme is better and the difference is obvious, achieving unexpected technical effects.

[0087] V. Tensile Strength Test

[0088] The mechanical properties of the samples were tested using a 1036PC universal testing machine, in accordance with the national standard "Test Method for Strength of Cement Mortar" (GB / T17671-1999).

[0089] 1. Test failure modes such as Figure 8 As shown. At the end of the test, all groups of specimens basically failed along the direction of the loading diameter (bonding crack), and the test results are valid.

[0090] The sandstone samples bonded with epoxy resin exhibited brittle fracture, accompanied by a distinct cracking sound during tensile testing. Furthermore, a layer of sandstone adhered to the adhesive on the fracture surface inside the samples, possibly due to two reasons: firstly, the inherently low tensile strength of the weathered sandstone itself; secondly, the adhesive penetrating the sandstone pores during bonding, enhancing the combined tensile strength of both. The internal splitting surfaces of the samples showed depressions or protrusions, possibly due to poor adhesive filling of the sandstone's anisotropy, resulting in uneven stress distribution during loading. Sandstone samples bonded with hydraulic lime (+5% ultrafine cement + 0.5% water glass) and hydraulic lime (+12% ultrafine cement + 1% water glass) both failed along the bonding surface, accompanied by a faint cracking sound, indicating brittle fracture, with minimal rock damage.

[0091] 2. During the splitting test, the change in vertical pressure on the specimen over time is as follows: Figure 9 As shown in the figure, the sandstone samples repaired by the three bonding materials all exhibited brittle failure.

[0092] 3. Determine the peak pressure of the specimen based on the failure curve, and then substitute it into the tensile strength calculation formula to obtain the tensile strength of the specimen. The calculation results are shown in Table 5.

[0093] Table 5. Tensile strength test results of sandstone specimens of cultural relics after restoration with different adhesive materials.

[0094]

[0095]

[0096] Table 5 shows that the tensile strength of sandstone repaired by bonding with 97% epoxy resin and 3% metakaolin can be restored to 72.19% of the original tensile strength. This indicates that epoxy resin and metakaolin have stronger repair capabilities and excellent bonding effects, making them suitable for the restoration of cultural relics involving large quantities of rock blocks. Two other bonding materials were also mentioned: 84.5% hydraulic lime + 5% ultrafine cement + 0.5% water glass + 10% water and 76% hydraulic lime + 12% ultrafine cement + 1% water glass + 11% water. The tensile strength of the sandstone samples after material repair recovered to 637.97% and 43.32% of the original rock, respectively. In terms of the degree of tensile strength recovery, the repair effect of the adhesive materials from best to worst was as follows: 97% epoxy resin + 3% metakaolin, 76% hydraulic lime adhesive + 12% ultrafine cement + 1% water glass + 11% water, and 84.5% hydraulic lime + 5% ultrafine cement + 0.5% water glass + 10% water. The tensile strength recovery effect of the adhesive materials obtained in each comparative proportion was worse.

[0097] In summary, the adhesive materials provided in this application include adhesive and grout, both of which are suitable for repairing rock blocks with cracks of different thicknesses and specifications. Grout has better fluidity than adhesive and is suitable for repairing larger rock blocks, mainly because the larger the rock block, the greater its weight and the greater the risk of it falling off. For larger rock blocks, adhesive materials with stronger adhesion are suitable for repair. For repairing relatively thin rock blocks that have peeled off, epoxy resin cannot be used because although epoxy resin has high bonding strength, it also has the problem of high expansion. Thicker rock blocks and larger cracks can withstand the stress caused by expansion, while relatively thin rock blocks are suitable for repairing with adhesives with low expansion. Therefore, this application provides different adhesives and their construction schemes for different situations.

[0098] Furthermore, this patent is only applicable to the bonding of sandstone artifacts in specific flaky weathered areas. For other types of sandstone defects, the applicability can be adjusted based on relevant test data.

[0099] The above specific embodiments are merely explanations of the present invention and are not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to these embodiments without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. An adhesive material for the protection of sandstone artifacts, characterized in that, Including adhesive and grout, the adhesive is composed of the following components by mass ratio: 12-18% ultrafine silicate cement, 0.5-1% water glass, 8-12% water, and 70-76% hydraulic lime; The grouting material consists of the following components: 97-98% epoxy resin and 2-3% metakaolin.

2. The adhesive material for protecting sandstone artifacts as described in claim 1, characterized in that, The epoxy value of the epoxy resin is 0.25-0.

45.

3. A method for protecting sandstone cultural relics using the adhesive material described in any one of claims 1-2, characterized in that, Includes the following steps: S1. Remove sand and dust from the cracks; S2. Bury grouting pipes in the cracks; S3. Sealing: Seal the crack opening from bottom to top; S4. Gas test: Gas is introduced into the grouting pipe to check the sealing effect of the cracks and to repair any leaks. S5. Grout preparation: Prepare the appropriate grouting material and adhesive material according to the size of the crack and the thickness of the rock block. S6. Grouting: Grout the prepared grout in S5 from bottom to top according to the pre-embedded grouting pipe; for the deepest small cracks that cannot be reached by the grouting pipe, inject adhesive material by injecting a syringe or drilling small holes. S7. Sealing: Use the adhesive prepared in S5 to seal the surface cracks and grouting pipes, and then use rock powder, mineral pigments and repair mortar to age the surface.

4. The method for protecting sandstone cultural relics as described in claim 3, characterized in that, In S1, the sand and dust in the fissures are treated by air compressor at a pressure of 0.2-0.5MPa.

5. The method for protecting sandstone cultural relics as described in claim 3, characterized in that, In S2, the spacing between grouting pipes is 0.5-1m, the pipe diameter matches the crack opening gap, and the burial depth is 0.2-0.4m.

6. The method for protecting sandstone cultural relics as described in claim 3, characterized in that, In S4, the pressure of the gas introduced for gas detection is 0.15-0.2 MPa.

7. The method for protecting sandstone cultural relics as described in claim 3, characterized in that, In S6, the grout injection pressure is 0.15-0.2 MPa.

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