Attapulgite modified hydraulic lime-based material and application thereof

Abstract

The invention belongs to the technical field of stone cultural relic protection, and particularly relates to an attapulgite modified hydraulic lime-based material and application thereof. The attapulgite modified hydraulic lime-based material provided by the invention comprises an inorganic cementing material, wherein the inorganic cementing material is a mixture of attapulgite clay and natural hydraulic lime. Slurry obtained by compounding the attapulgite modified hydraulic lime-based material provided by the invention with water has the characteristics of good dispersity, controllable fluidity and setting time within a certain range, low shrinkage rate, high early strength, environmental harmlessness and the like. In addition, the admixture is doped, so that the construction performance and the protection performance of the material can be further improved. The attapulgite modified hydraulic lime-based material provided by the invention has relatively high applicability to crack development diseases of stone cultural relics, and has a good use effect in grouting reinforcement of the crack diseases of the stone cultural relics.

Description

Technical Field

[0001] The invention belongs to the technical field of stone cultural relics protection, and in particular relates to an attapulgite-modified hydraulic lime-based material and application thereof. Background Art

[0002] Stone cultural relics such as grotto temples, cliff sculptures, and inscriptions have been exposed to the natural environment for a long time and have been affected by the harsh factors of the environment. They have developed defects such as flaky cracks and water seepage in cracks, which have caused the stone cultural relics to lose their integrity and stability and seriously affected their survival.

[0003] Grouting is the most direct and effective treatment measure for cracking of stone cultural relics to improve rock stability and interfere with the seepage path of fissures. It is also one of the key technologies for the protection of grotto temples. However, the weathering and cracking of stone cultural relics are complex, the phenomenon of water seepage in fissures is weak, and the seepage channels are difficult to detect. Its treatment faces many technical difficulties. Compared with the current mature grouting construction technology, the lack of grouting reinforcement materials suitable for the fissure diseases of stone cultural relics is a key issue in the protection and reinforcement of stone cultural relics.

[0004] Natural hydraulic lime has been widely used in the field of ancient building restoration in recent years due to its advantages of low soluble salt content, low shrinkage and moderate strength. However, when used in complex environments, natural hydraulic lime has the disadvantages of difficult to control fluidity and setting time, insufficient early strength, need to improve durability, and poor pourability. Therefore, it is necessary to modify natural hydraulic lime to meet the needs of grouting reinforcement of stone cultural relics. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a attapulgite-modified hydraulic lime-based material and its application. The attapulgite-modified hydraulic lime-based material provided by the present invention has a good use effect in the grouting reinforcement of crack diseases in stone cultural relics.

[0006] The invention provides an attapulgite-modified hydraulic lime-based material, which comprises an inorganic gelling material, wherein the inorganic gelling material is a mixture of attapulgite clay and natural hydraulic lime.

[0007] Preferably, the content of the attapulgite clay in the inorganic gelling material is 20-45wt%.

[0008] Preferably, the attapulgite clay has a content of >85 wt%, a median particle size of 1 to 5 μm, and a specific surface area of ​​160 to 200 m 2 / g.

[0009] Preferably, the natural hydraulic lime is one or more of NHL2, NHL3.5 and NHL5, and the median particle size is 2 to 20 μm.

[0010] Preferably, the composition further comprises an additive.

[0011] Preferably, the admixture is one or more of an early strength agent, a water reducing agent, a defoaming agent, an expansion agent, a retarder and an antifreeze-thaw agent.

[0012] Preferably, the content of the admixture in the attapulgite-modified hydraulic lime-based material is 0.1-2 wt %.

[0013] The invention provides an attapulgite-modified hydraulic lime-based grouting material, the components of which include the attapulgite-modified hydraulic lime-based material described in the above technical solution and water.

[0014] Preferably, the mass ratio of the attapulgite modified hydraulic lime-based material to water is 100:(40-150).

[0015] The present invention provides a method for reinforcing cracks in stone cultural relics, comprising the following steps:

[0016] The attapulgite-modified hydraulic lime-based grouting material described in the above technical solution is used to grout and reinforce the cracks of stone cultural relics.

[0017] Compared with the prior art, the present invention provides a attapulgite-modified hydraulic lime-based material and its application. The components of the attapulgite-modified hydraulic lime-based material provided by the present invention include an inorganic cementitious material, and the inorganic cementitious material is a mixture of attapulgite clay and natural hydraulic lime. The slurry after compounding the attapulgite-modified hydraulic lime-based material provided by the present invention with water has the characteristics of good dispersibility, fluidity and setting time controllable within a certain range, low shrinkage, high early strength, environmental harmlessness, etc. In addition, the addition of admixtures can further improve the construction performance and protective performance of the material. The attapulgite-modified hydraulic lime-based material provided by the present invention has high applicability to the crack development disease of stone cultural relics, and has a good use effect in the grouting reinforcement of crack diseases of stone cultural relics. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0019] Figure 1 It is a SEM image of the attapulgite clay provided in the embodiment of the present invention. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The invention provides an attapulgite-modified hydraulic lime-based material, the components of which include an inorganic gelling material, wherein the inorganic gelling material is a mixture of attapulgite clay and natural hydraulic lime.

[0022] In the attapulgite-modified hydraulic lime-based material provided by the present invention, the natural hydraulic lime is a light gray powder; the natural hydraulic lime is preferably one or more of NHL2, NHL3.5 and NHL5; the soluble salt content of the natural hydraulic lime is preferably <1wt%, and the purity is preferably >95%; the median particle size of the natural hydraulic lime is preferably 2 to 20 μm.

[0023] In the attapulgite-modified hydraulic lime-based material provided by the present invention, the attapulgite clay is white or light gray powder; the content of attapulgite in the attapulgite clay is preferably greater than 85wt%; the median particle size of the attapulgite clay is preferably 1 to 5μm; the specific surface area of ​​the attapulgite clay is preferably 160 to 200m 2 / g.

[0024] In the attapulgite modified hydraulic lime-based material provided by the present invention, the content of the attapulgite clay in the inorganic gelling material is preferably 20-45wt%, specifically 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, 31wt%, 32wt%, 33wt%, 34wt%, 35wt%, 36wt%, 37wt%, 38wt%, 39wt%, 40wt%, 41wt%, 42wt%, 43wt%, 44wt% or 45wt%.

[0025] In the attapulgite-modified hydraulic lime-based material provided by the present invention, the components thereof preferably also include an admixture to achieve functional reinforcement and protection.

[0026] In the attapulgite-modified hydraulic lime-based material provided by the present invention, the admixture is preferably one or more of an early strength agent, a water reducing agent, a defoaming agent, an expansion agent, a retarder and an antifreeze-thaw agent.

[0027] In the attapulgite modified hydraulic lime-based material provided by the present invention, the content of the admixture in the attapulgite modified hydraulic lime-based material is preferably 0.1-2wt%, specifically 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt% or 2wt%.

[0028] The present invention has no particular limitation on the preparation method of the attapulgite-modified hydraulic lime-based material, and the raw materials can be uniformly mixed according to the component ratio.

[0029] The present invention also provides a attapulgite-modified hydraulic lime-based grouting material, the composition of which includes the attapulgite-modified hydraulic lime-based material described in the above technical solution and water. Wherein, the mass ratio of the attapulgite-modified hydraulic lime-based material to water is preferably 100:(40-150), specifically 100:40, 100:50, 100:60, 100:70, 100:80, 100:90, 100:100, 100:110, 100:120, 100:130, 100:140 or 100:150.

[0030] The present invention has no particular limitation on the preparation method of the attapulgite-modified hydraulic lime-based grouting material, and the raw materials can be uniformly mixed according to the component ratio.

[0031] The present invention also provides a method for reinforcing cracks in stone cultural relics, comprising the following steps:

[0032] The attapulgite-modified hydraulic lime-based grouting material described in the above technical solution is used to grout and reinforce the cracks of stone cultural relics.

[0033] The technical solution provided by the present invention has a good use effect in the grouting reinforcement of crack diseases in stone cultural relics. More specifically, it has at least the following advantages:

[0034] (1) The present invention utilizes the inherent characteristics of attapulgite clay and natural hydraulic lime. The slurry after compounding with water has the advantages of good dispersibility, good fluidity, moderate viscosity, and controllable curing time, which is conducive to the development of grouting reinforcement work. At the same time, the cured material has good compatibility with rocks, low soluble salt content, suitable strength, and low permeability.

[0035] (2) The attapulgite clay used in the present invention is a hydrous magnesium aluminum silicate with a unique three-dimensional chain structure and a special needle and rod-shaped crystal structure, and has the advantages of stable chemical properties, strong bonding force, and large adsorption capacity. At the same time, attapulgite clay is a highly volcanic ash active mineral, which can significantly improve the pore structure and mechanical strength of the material by promoting the chemical reaction rate inside natural hydraulic lime.

[0036] (3) The preparation process of the modified grouting material provided by the present invention is simple, and the addition of attapulgite clay greatly reduces the preparation cost of the grouting material, and has a large-scale application prospect in the grouting reinforcement project of stone cultural relics cracks.

[0037] (4) The modified grouting material provided by the present invention is used to reinforce and protect stone cultural relics that have cracks, and the effect is remarkable. The grouting material has good stability, applicability and safety for stone cultural relics. At the same time, admixtures can be added according to the needs of stone cultural relics to achieve functional reinforcement and protection.

[0038] For the purpose of greater clarity, the present invention is described in detail with reference to the following examples and comparative examples.

[0039] In the following examples and comparative examples, the median particle size of natural hydraulic lime (NHL5) is in the range of 2 to 20 μm and is purchased from Shanghai Desaibao Building Materials Co., Ltd.; the content of attapulgite in attapulgite clay is greater than 85 wt %, the median particle size is in the range of 1 to 5 μm, and the specific surface area is 160 to 200 m 2 / g, microscopic morphology Figure 1 As shown, it was purchased from McLean Biological Co., Ltd.; the expansion agent was purchased from Henan Tianchou Chemical Products Co., Ltd.; the early strength agent, water reducing agent, defoaming agent, and retarder were purchased from Guangzhou Zhongwan New Materials Co., Ltd.; the antifreeze-thaw agent was purchased from Beijing Mengtai Building Materials Weiye.

[0040] Example 1

[0041] Natural hydraulic lime (NHL5) and attapulgite clay are mixed evenly in a mass ratio of 7:3, and then an early strength agent (lithium carbonate) accounting for 1% of the total weight is added and mixed evenly; the mixed materials are mixed evenly with water in a mass ratio of 1:0.6, and after stirring with a mortar mixer, an attapulgite-modified hydraulic lime-based slurry for grouting reinforcement of stone cultural relics is obtained.

[0042] The slurry prepared in this embodiment has high early strength, and the uniaxial compressive strength after 7 days of curing can reach 8 MPa, and the uniaxial compressive strength after 28 days of curing is 19.4 MPa. It has a good grouting reinforcement effect for cracks in stone cultural relics with high bedrock strength and urgent repair needs.

[0043] Example 2

[0044] Natural hydraulic lime (NHL5) and attapulgite clay are mixed evenly in a mass ratio of 3:1, and then 0.2% of the total weight of a water reducer (with methacrylic acid as the main chain and polyethers with different side chain lengths grafted thereon) is added and mixed evenly; the evenly mixed materials are mixed evenly with water in a mass ratio of 1:0.6, and after stirring with a mortar mixer, an attapulgite-modified hydraulic lime-based slurry for grouting reinforcement of stone cultural relics is obtained.

[0045] The slurry prepared in this embodiment has good dispersibility and fluidity. The fluidity of the freshly mixed slurry can reach 237.5 mm. It has a good grouting reinforcement effect on flaky cracking diseases of stone cultural relics and deep and small cracks in the bedrock.

[0046] Example 3

[0047] Natural hydraulic lime (NHL5) and attapulgite clay are mixed evenly in a mass ratio of 7:3, and then a defoamer (polyether and silicone) accounting for 0.5% of the total weight is added and mixed evenly; the mixed material is mixed evenly with water in a mass ratio of 1:0.6, and after stirring with a mortar mixer, an attapulgite-modified hydraulic lime-based slurry for grouting reinforcement of stone cultural relics is obtained.

[0048] The slurry prepared in this embodiment has a high density after solidification, and the wave speed of ultrasonic detection can reach 2.87 km / s. It is suitable for grouting reinforcement with high requirements for impermeability, such as sealing of surface cracks of stone cultural relics and water seepage in bedrock cracks.

[0049] Example 4

[0050] Natural hydraulic lime (NHL5) and attapulgite clay are mixed evenly in a mass ratio of 7:3, and then an expansion agent (calcium sulphoaluminate) accounting for 0.3% of the total weight is added and mixed evenly; the mixed material is mixed evenly with water in a mass ratio of 1:0.6, and after stirring with a mortar mixer, an attapulgite-modified hydraulic lime-based slurry for grouting reinforcement of stone cultural relics is obtained.

[0051] The slurry prepared in this embodiment has an extremely small shrinkage rate after solidification, which can reach 0.1%. It is suitable for stone cultural relics and their bedrock with large range and wide volume open cracks. After grouting and solidification, the slurry will basically not shrink and crack.

[0052] Example 5

[0053] Natural hydraulic lime (NHL5) and attapulgite clay are mixed evenly in a mass ratio of 4:1, and then 0.1% of the total weight of a retarder (low molecular weight cellulose and its derivatives) is added and mixed evenly; the mixed material is mixed evenly with water in a mass ratio of 1:0.6, and after stirring with a mortar mixer, an attapulgite-modified hydraulic lime-based slurry for grouting reinforcement of stone cultural relics is obtained.

[0054] The initial setting time and final setting time of the slurry prepared in this embodiment reached 476 minutes and 712 minutes respectively, which is suitable for grouting reinforcement of cracks that are difficult to detect inside stone cultural relics, unknown seepage paths in bedrock, and large grouting projects with special requirements for construction technology and techniques.

[0055] Example 6

[0056] Natural hydraulic lime (NHL5) and attapulgite clay are mixed evenly in a mass ratio of 4:1, and then an antifreeze-thaw agent (calcium chloride) accounting for 2% of the total weight is added and mixed evenly; the evenly mixed materials are mixed evenly with water in a mass ratio of 1:0.6, and after stirring with a mortar mixer, an attapulgite-modified hydraulic lime-based slurry for grouting reinforcement of stone cultural relics is obtained.

[0057] After solidification, the slurry prepared in this embodiment can experience 10 freeze-thaw cycles at a low temperature of -20°C and a high temperature of 30°C without cracking or breakage under conditions of high humidity. The mass loss rate after 20 freeze-thaw cycles at a low temperature of -20°C and a high temperature of 30°C is less than 3%. The slurry is suitable for grouting reinforcement of fissure diseases in stone cultural relics under freeze-thaw environments.

[0058] Example 7

[0059] Compared with Example 2, the only difference is that the admixture is a naphthalene-based water reducer.

[0060] Example 8

[0061] Compared with Example 5, the only difference is that the admixture is a sodium fluorosilicate retarder.

[0062] Comparative Example 1

[0063] Compared with Example 1, the only difference is that no attapulgite clay is added, that is, the cementitious material is all natural hydraulic lime (NHL5).

[0064] The early strength of natural hydraulic lime grouting materials after curing is low, and the performance development does not meet the protection requirements of grouting reinforcement of stone cultural relics.

[0065] Comparative Example 2

[0066] Compared with Example 2, the only difference is that the addition of water reducing agent is omitted.

[0067] Due to the lack of water reducing agent, the fluidity of the grouting material decreases. In the application scenario of grouting reinforcement of stone cultural relics, the grout with low fluidity has poor dispersion and cannot be poured into the fine cracks.

[0068] Comparative Example 3

[0069] Compared with Example 3, the only difference is that the addition of the defoaming agent is omitted.

[0070] Due to the absence of defoaming agent, the hardened slurry has a certain porosity and its impermeability decreases, which limits its effect on sealing crack seepage damage.

[0071] Comparative Example 4

[0072] Compared with Example 6, the only difference is that the addition of the antifreeze-thaw agent is omitted.

[0073] Due to the absence of antifreeze-thaw agents, tiny cracks appeared on the surface of the hardened slurry after 10 freeze-thaw cycles, and the anti-freeze-thaw performance decreased.

[0074] Performance data

[0075] The slurries prepared in Examples 1 to 8 and Comparative Examples 1 to 4 were tested for key physical and chemical properties, and the test standards included: "Method for Determination of Fluidity of Cement Mortar" (GB / T 2419-2016), SL\T 62-2020 "Technical Specification for Cement Grouting Construction of Hydraulic Structures", "Test Method for Water Consumption, Setting Time and Stability of Cement Standard Consistency" (GB / T1346-2011), MT 224-90 "Method for Determination of Permeability Coefficient of Coal and Rock", JGJ / T 70-2009 "Standard for Test Methods for Basic Properties of Building Mortar", GB / T 15193.3-2014 "National Food Safety Standard Acute Oral Toxicity Test", and JGJ / T322-2013 "Technical Specification for Detection of Chloride Ion Content in Concrete". The test results are shown in Tables 1 to 2.

[0076] Table 1 Physical properties test results

[0077]

[0078] Table 2 Chemical performance test results

[0079]

[0080] It can be seen from Tables 1 to 2 that the attapulgite modified hydraulic lime-based grouting material provided by the present invention has good construction and mechanical properties, and at the same time has lower shrinkage, permeability and soluble salt content, which indicates that the grouting material of the present invention is more conducive to grouting operation, has good compatibility with stone cultural relics, has a smaller shrinkage rate after hardening, is not prone to secondary cracking, and has better sealing and anti-seepage effects on cracks.

[0081] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An attapulgite-modified hydraulic lime-based material, characterized in that: The composition includes an inorganic cementitious material which is a mixture of attapulgite clay and natural hydraulic lime.

2. The attapulgite-modified hydraulic lime-based material according to claim 1, characterized in that: The content of the attapulgite clay in the inorganic gelling material is 20-45wt%.

3. The attapulgite-modified hydraulic lime-based material according to claim 1, characterized in that: The attapulgite clay has a content of >85 wt%, a median particle size of 1 to 5 μm, and a specific surface area of ​​160 to 200 m 2 / g.

4. The attapulgite-modified hydraulic lime-based material according to claim 1, characterized in that: The natural hydraulic lime is one or more of NHL2, NHL3.5 and NHL5, and the median particle size is 2 to 20 μm.

5. The attapulgite-modified hydraulic lime-based material according to claim 1, characterized in that: The composition also includes admixtures.

6. The attapulgite-modified hydraulic lime-based material according to claim 5, characterized in that: The admixture is one or more of an early strength agent, a water reducing agent, a defoaming agent, an expansion agent, a retarder and an antifreeze-thaw agent.

7. The attapulgite-modified hydraulic lime-based material according to claim 5, characterized in that: The content of the admixture in the attapulgite-modified hydraulic lime-based material is 0.1-2 wt %.

8. An attapulgite-modified hydraulic lime-based grouting material, characterized in that: The ingredients include the attapulgite-modified hydraulic lime-based material according to any one of claims 1 to 7 and water.

9. The attapulgite-modified hydraulic lime-based grouting material according to claim 8, characterized in that: The mass ratio of the attapulgite modified hydraulic lime-based material to water is 100:(40-150).

10. A method for reinforcing cracks in stone cultural relics, characterized in that: The following steps are involved: The attapulgite-modified hydraulic lime-based grouting material described in claim 8 or 9 is used to grout and reinforce the cracks of stone cultural relics.

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