Coral sand reinforcing material as well as preparation method and application thereof

Abstract

The invention discloses a coral sand reinforcing material as well as a preparation method and application thereof. The coral sand reinforcing material is prepared from the following raw materials in parts by mass: 7-24 parts of polyhydric alcohol, 7-24 parts of isocyanate and 1000 parts of coral sand. According to the invention, the polyhydric alcohol is used as a white material, the polyhydric alcohol contains a plurality of hydroxyl functional groups, polyurethane macromolecular chains are formed through reaction between isocyanate groups and hydroxyl groups, and the macromolecular chains are interwoven to form a three-dimensional network structure, so that the integrity and the vibration energy dissipation capability of a coral sand sample can be effectively improved, and the problem that coral sand is easy to break is solved. Compared with a polymer added with combined polyether and isocyanate, the reaction time of the polymer in the reinforced coral sand is short, the strength of a coral sand sample can reach 90% within 24 h, the coral sand sample reaches the optimal state after being cured for 3 days, the curing time is shortened, and the cost is reduced. And the cohesive force of the coral sand reinforcing material and the curing time are in a good linear relationship.

Description

Technical Field

[0001] The invention relates to the technical field of calcareous sand materials, and in particular to a coral sand reinforcement material and a preparation method and application thereof. Background Art

[0002] Since the calcium content of coral sand can generally reach more than 90%, it is easy to break, has irregular particle shape, high specific gravity and many pores. Its engineering properties are characterized by high compressibility and easy breakage. When coral sand is used as a material for infrastructure buildings, it is easily washed away by rain and waves, resulting in low foundation bearing capacity and high looseness, which in turn leads to safety hazards such as uneven foundation settlement, which seriously affects the commissioning of infrastructure.

[0003] At present, there is no unified standard for the treatment of coral sand foundations, and scholars at home and abroad have explored different reinforcement methods. A type of adhesive material based on polymer compounds has been increasingly widely used in various fields of modern industry. In recent years, it has been widely used in water conservancy projects, bridges and tunnels, rock support and other engineering construction links, and research on the mechanical properties of polymer reinforced sand materials has also been carried out. In addition, some studies have used microbial reinforcement to use microorganisms to induce calcium carbonate precipitation to improve the mechanical properties of coral sand foundations, but it is environmentally sensitive and technically complex, and it is difficult to promote and apply; there are also studies that use cement reinforcement, which can greatly improve the strength of consolidated soil, but on the one hand, cement solidification of sand requires a long curing time, and on the other hand, while increasing the strength, it will also increase the stiffness and brittleness of the soil, and cracks are prone to appear under the action of earthquakes. Therefore, how to use polymer compounds to reinforce coral sand to produce high-strength building materials is a problem that needs to be solved. Summary of the invention

[0004] In order to overcome the problems existing in the above-mentioned prior art, one of the purposes of the present invention is to provide a coral sand reinforcement material. The second purpose of the present invention is to provide a preparation method of the above-mentioned coral sand reinforcement material. The third purpose of the present invention is to provide an application of the above-mentioned coral sand reinforcement material.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The first aspect of the present invention provides a coral sand reinforcement material, comprising the following raw materials: 7 to 30 parts of polyol, 7 to 30 parts of isocyanate, and 1000 parts of coral sand.

[0007] The coral sand reinforcement material of the present invention uses polyol as white material and isocyanate as black material. The polyol contains multiple hydroxyl (-OH) functional groups. After the black and white materials are mixed, polyurethane polymer chains are formed through the reaction between the isocyanate group and the hydroxyl group (called polyurethane reaction). These polymer chains are intertwined to form a three-dimensional network structure, thereby obtaining the coral sand reinforcement material.

[0008] Preferably, it is prepared from the following raw materials: 20-30 parts of polyol, 20-30 parts of isocyanate alcohol, and 1000 parts of coral sand.

[0009] Preferably, the polyol is selected from at least one of ethylene glycol, glycerol, 1,4-butanediol and pentaerythritol.

[0010] The present invention adopts a polyol with a regular structure to synthesize a polyurethane adhesive, and the obtained polyurethane adhesive has strong crystallinity and high bonding strength. Glycerol is further used as a preparation raw material. The role of glycerol in the synthesis of polyurethane adhesive is as follows: 1. Polyol component: glycerol, as a polyol component, can undergo polycondensation reaction with other reactants to generate a polymer chain, thereby forming the basic skeleton of the polyurethane adhesive; 2. Improve flexibility: The introduction of glycerol can increase the flexibility of the polyurethane molecular chain, thereby improving the elasticity and tensile properties of the polyurethane adhesive; 3. Improve water solubility: glycerol, as a hydrophilic group, can increase the water solubility of the polyurethane adhesive, making it easier to disperse in water and improving its applicability in certain application fields.

[0011] Preferably, the mass ratio of the polyol to isocyanate is 1:(0.8-1.2).

[0012] Preferably, the particle size of the coral sand is less than 2 mm; and / or the porosity ratio of the coral sand is 0.655-1.554.

[0013] Preferably, the coral sand is produced in the South China Sea.

[0014] The second aspect of the present invention provides a method for preparing the coral sand reinforcement material described in the first aspect, comprising the following steps: mixing polyol, isocyanate and coral sand to obtain a mixture, pouring the mixture into a mold, and obtaining the coral sand reinforcement material after curing.

[0015] Preferably, the coral sand is washed and dried before mixing.

[0016] Preferably, the mixing step comprises: firstly mixing isocyanate with coral sand, and then adding polyol and mixing to obtain a mixture.

[0017] More preferably, the mixing time of the isocyanate and the coral sand is 40 to 120 seconds.

[0018] More preferably, the polyol is added and mixed for a mixing time of 20 to 40 seconds.

[0019] Preferably, the specific process of pouring into the mold includes: filling the mixture into the mold using a layered compaction method.

[0020] Preferably, the curing time is 20 to 100 hours.

[0021] The third aspect of the present invention provides the use of the coral sand reinforcement material described in the first aspect in preparing a coral sand foundation.

[0022] Preferably, the coral sand reinforcement material is used in the preparation of coral sand-based artificial islands and reefs.

[0023] The beneficial effects of the present invention are:

[0024] The invention provides a coral sand reinforcement material, wherein the reinforcement material uses polyol as white material and isocyanate as black material, and the polyol contains multiple hydroxyl (-OH) functional groups. After the black and white materials are mixed, polyurethane polymer chains are formed by reacting between isocyanate groups and hydroxyl groups. These polymer chains are interwoven to form a three-dimensional network structure, which changes the internal organization of the coral sand sample and the contact mode between particles, and can effectively improve the integrity and the ability of the coral sand sample to dissipate vibration energy. In the case of low polymer incorporation, compared with no polymer reinforced coral sand, its dynamic shear modulus can reach 240MPa, which solves the problem that coral sand is easy to break, and ensures that island and reef engineering facilities can be used and maintained normally under earthquake action. The polymer in the reinforced coral sand of the present invention has a faster reaction time than the polymer added with combined polyether and isocyanate, and the strength of the coral sand sample can reach 90% after curing for 24h. After 3 days of curing, it has reached the best state, which is conducive to shortening the curing time, and the cohesion of the coral sand reinforcement material is in a good linear relationship with the curing time. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The process flow for preparing coral sand reinforcement material;

[0026] Figure 2 Illustration of the mixer used for the preparation process;

[0027] Among them, 1 is the control console, which sets the stirring program; 2 is the stirring chamber; 3 is the white material nozzle; 4 is the black material nozzle; 5 is the fixing frame;

[0028] Figure 3 The results of dynamic shear modulus of coral sand reinforced with different polymer dosages;

[0029] Figure 4 Results of damping ratio of coral sand reinforced with different polymer addition amounts. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below through specific examples. The raw materials used in the following examples, unless otherwise specified, can be obtained from conventional commercial sources or prepared and separated by simple synthesis; the processes used, unless otherwise specified, are conventional processes in the art.

[0031] The raw materials used in the following examples and comparative examples are as follows: isocyanate was purchased from Shanghai Guangsheng Building Materials Co., Ltd. and is polymerized MD; glycerol was purchased from Sinopharm Reagent Network and its brand is Hushi.

[0032] Raw material processing: The coral sand produced in the South China Sea is cleaned and dried, taken out and cooled to room temperature, and the dried coral sand is placed in a vibrating screen for screening to remove coral sand particles with a particle size greater than 2 mm. The porosity of the coral sand varies from 0.655 to 1.554, and the specific gravity of the coral sand Gs is 2.81 tons / cubic meter.

[0033] Example 1

[0034] This embodiment provides a coral sand reinforcement material, the raw materials used are calculated by mass as follows: 7.5 parts of white material, 7.5 parts of black material, and 985 parts of coral sand; the black material is isocyanate, the white material is glycerol, and G c is 1.5%; the preparation method of coral sand reinforcement material is as follows Figure 1 , as follows:

[0035] S1, add 985 parts of coral sand into Figure 2 In the mixer shown, stirring is first set for 5 minutes to evenly distribute the coral sands of various particle sizes, and then 7.5 parts of white material are added through the side white material nozzle 3, and the switch is turned on to fully stir it for 60 seconds to prepare a mixture of coral sand and white material; then 7.5 parts of black material are added through the black material nozzle 4, and fully stirred to prepare a mixture for 30 seconds;

[0036] S2. The mixture is compacted by layering method. The sample is divided into four layers and compacted and scraped separately. Then, the layers are loaded into the mold. The sample in the mold is cured for 3 days to obtain the coral sand reinforcement material.

[0037] Example 2

[0038] This embodiment provides a coral sand reinforcement material, the raw materials used are calculated by mass as follows: 15 parts of white material, 15 parts of black material, and 970 parts of coral sand; the black material is isocyanate, the white material is glycerol, and G c 3%; the preparation method of coral sand reinforcement material is as follows Figure 1 , as follows:

[0039] S1, add 970 parts of coral sand into Figure 2 In the mixer shown, stirring is first set for 5 minutes to evenly distribute the coral sands of various particle sizes, and then 15 parts of white material are added through the side white material nozzle 3, and the switch is turned on to fully stir it evenly. The stirring time is 60 seconds to prepare a mixture of coral sand and white material; then 15 parts of black material are added through the black material nozzle 4, and fully stirred to prepare a mixture. The stirring time is 30 seconds;

[0040] S2. The mixture is compacted by layering method. The sample is divided into four layers and compacted and scraped separately. Then, the layers are loaded into the mold. The sample in the mold is cured for 3 days to obtain the coral sand reinforcement material.

[0041] Example 3

[0042] This embodiment provides a coral sand reinforcement material, the raw materials used are calculated by mass: 22.5 parts of white material, 22.5 parts of black material, and 955 parts of coral sand; the black material is isocyanate, the white material is glycerol, and G c is 4.5%; the preparation method of coral sand reinforcement material is as follows Figure 1 , as follows:

[0043] S1, add 955 parts of coral sand into Figure 2 In the mixer shown, stirring is first set for 5 minutes to evenly distribute the coral sands of various particle sizes, and then 22.5 parts of white material are added through the side white material nozzle 3, and the switch is turned on to fully stir it for 60 seconds to prepare a mixture of coral sand and white material; then 22.5 parts of black material are added through the black material nozzle 4, and fully stirred to prepare a mixture for 30 seconds;

[0044] S2. The mixture is compacted by layering method. The sample is divided into four layers and compacted and scraped separately. Then, the layers are loaded into the mold. The sample in the mold is cured for 3 days to obtain the coral sand reinforcement material.

[0045] Comparative Example 1

[0046] Comparative Example 1 provides a non-reinforced coral sand, the raw materials used are calculated by mass as follows: 1000 parts of coral sand, G c 0%; the preparation method is as follows:

[0047] The coral sand is compacted by layering method. The sample is divided into four layers and compacted and scraped separately. After that, they are loaded into the mold. The sample in the mold is cured for 3 days to obtain the coral sand material.

[0048] Experimental analysis

[0049] The coral sand reinforcement materials of Examples 1-3 and the material of Comparative Example 1 were made into test specimens, and the dry density of the specimens was 1.5 g / cm 3The size of the specimen is a cylinder with a diameter of 50 mm and a height of 100 mm. The resonant column test is carried out under a load condition of a consolidation pressure of 200 kPa.

[0050] Figure 3 The dynamic shear modulus of coral sand reinforced with different polymer content is shown in Figure 2. Figure 3 It can be seen that the shear modulus position of different curves moves up with the increase of polymer content. When the polymer content increases from 0.0% to 1.5%, the increase in dynamic shear modulus is small. As the content continues to increase, the growth rate of dynamic shear modulus increases significantly. The growth rate of dynamic shear modulus increases with the increase of polymer content. Under a confining pressure of 200kpa, with the increase of polymer content (0.0%-4.5%), the dynamic shear modulus increases by 10, 40, and 80MPa respectively compared with plain coral sand, thereby enhancing the ability to resist shear deformation. The stronger the ability to resist deformation under earthquake action, the more stable the sample.

[0051] Figure 4 The damping ratio of coral sand reinforced with different polymer content is shown in Figure 2. Figure 4 It can be seen that the damping ratio of solidified coral sand is higher than that of pure coral sand. In addition, the damping ratio of solidified coral sand shows an increasing trend with the increase of polymer dosage. The larger the damping ratio, the maximum damping is 200%, 280%, and 350% of the damping ratio of plain coral sand in the change of polymer dosage from 0.0% to 4.5%, and the faster the vibration attenuation rate of the sample, the more stable the sample.

[0052] In summary, the present invention uses polyol as white material, and polyol contains multiple hydroxyl (-OH) functional groups. After the black and white materials are mixed, polyurethane polymer chains are formed by reaction between isocyanate groups and hydroxyl groups. These polymer chains are interwoven to form a three-dimensional network structure, which changes the internal organization of the coral sand sample and the contact mode between particles. The integrity and the ability of the coral sand sample to dissipate vibration energy can be effectively improved, and the problem of easy breakage of coral sand is solved, and the island and reef engineering facilities can be normally used and maintained under earthquake action. The polymer in the reinforced coral sand of the present invention is faster than the polymer reaction time of adding combined polyether and isocyanate. The strength of the coral sand sample can reach 90% within 24h of curing. After 3 days of curing, it has reached the best state, which is conducive to shortening the curing time, and the cohesion of the coral sand reinforcement material is in a good linear relationship with the curing time. In addition, the preparation method of the present invention only requires sand and polymer, does not need to add water for mixing, is convenient to construct, has a fast reaction rate, meets the engineering demand for efficiency and cost, and has good environmental protection of the material, which can reduce the pollution and damage to the marine ecology.

[0053] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A coral sand reinforcement material, characterized in that: The preparation method comprises the following raw materials in parts by weight: 7 to 24 parts of polyol, 7 to 24 parts of isocyanate and 1000 parts of coral sand.

2. The coral sand reinforcement material according to claim 1, characterized in that: The polyol is selected from at least one of ethylene glycol, propylene glycol, 1,4-butanediol and pentaerythritol.

3. The coral sand reinforcement material according to claim 1, characterized in that: The mass ratio of the polyol to the isocyanate is 1:(0.8-1.2).

4. The coral sand reinforcement material according to claim 1, characterized in that: The particle size of the coral sand is less than 2 mm; and / or the porosity ratio of the coral sand is 0.655-1.

554.

5. The method for preparing the coral sand reinforcement material according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: mixing polyol, isocyanate and coral sand to obtain a mixture, pouring the mixture into a mold, and obtaining a coral sand reinforcement material after curing.

6. The method for preparing the coral sand reinforcement material according to claim 5, characterized in that: The mixing step comprises: firstly mixing isocyanate with coral sand, and then adding polyol to mix to obtain a mixture.

7. The method for preparing the coral sand reinforcement material according to claim 6, characterized in that: The isocyanate and coral sand are mixed for 40 to 120 seconds; and / or polyol is added for mixing for 20 to 40 seconds.

8. The method for preparing the coral sand reinforcement material according to claim 5, characterized in that: The specific process of pouring into the mold includes: filling the mixed material into the mold by using a layered compaction method.

9. The method for preparing the coral sand reinforcement material according to claim 5, characterized in that: The curing time is 20 to 100 hours.

10. Use of the coral sand reinforcement material according to any one of claims 1 to 4 in preparing a coral sand foundation.

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