Green high-strength concrete and preparation method and application thereof

Abstract

The application discloses green high-strength concrete and a preparation method and application thereof, and the preparation raw materials of the green high-strength concrete include steel slag stone, steel slag sand, cement, fly ash and modified steel fiber; the preparation raw materials of the modified steel fiber include steel fiber, gelatin particles, non-ionic surfactant and polylactic acid. The green high-strength concrete provided by the application can improve the bonding performance of the interface between the steel fiber and the concrete matrix, and can fill the gaps between the steel fiber and the matrix when the interface region is accumulated and rearranged, thereby improving the performance of the concrete.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of concrete, and particularly relates to a green high-strength concrete and a preparation method and application thereof. BACKGROUND

[0002] Due to the popularization of the green production concept, it is imperative to vigorously develop and use green building materials, fully utilize renewable resources, improve the quality of green buildings, promote the efficient treatment and recycling of construction waste, and realize low-carbon environmental protection, energy saving and emission reduction in the whole process of engineering construction. Today, with the rapid development of civil engineering construction, concrete has become the largest man-made product in the world, with an annual consumption second only to water. However, ordinary concrete consumes a lot of energy and causes serious environmental pollution in the production and preparation process, and overexploitation of raw materials will destroy the ecological environment of the production area, which is contrary to the requirements of sustainable development. In addition, with the substantial improvement of economy and people's living standards, people have higher requirements for the safety, quality and appearance of buildings. Therefore, it is particularly important to promote the engineering application of new eco-friendly high and easy green concrete materials.

[0003] Therefore, it is urgent to develop a green high-strength concrete. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the green high-strength concrete provided by the present application can not only improve the bonding performance of the steel fiber and the concrete matrix interface, but also fill the gaps when the interface area between the steel fiber and the matrix is accumulated and rearranged, thereby improving the performance of the concrete.

[0005] A green high-strength concrete according to an embodiment of the first aspect of the present application, the preparation raw materials of the green high-strength concrete include steel slag stone, steel slag sand, cement, fly ash and modified steel fiber.

[0006] The preparation raw materials of the modified steel fiber include steel fiber, gelatin particles, non-ionic surfactant and polylactic acid.

[0007] The embodiment according to the first aspect of the present application at least has the following beneficial effects:

[0008] The polylactic acid can form a layer of covering on the surface of the steel fiber, thereby improving the physical adhesion with the concrete matrix. The polylactic acid molecule contains a carboxyl (-COOH) functional group, and the hydration product and fly ash in the concrete are rich in hydroxyl (-OH). Thus, the carboxyl and hydroxyl groups undergo esterification to form an ester bond (-COO-), thereby firmly connecting the polylactic acid and the concrete matrix together; the carboxyl groups in the polylactic acid molecule also react with the cations (such as Ca 2+) ion exchange reaction occurs, forming a stable complex to further promote the binding between polylactic acid and the concrete matrix. As an interface transition layer between steel fibers and the concrete matrix, polylactic acid can improve the compatibility and adhesion between the two, fill the defects between steel fibers and the concrete matrix at the microscale, reduce stress concentration and improve the bonding strength of the interface.

[0009] When the concrete is subjected to external force, the steel fiber will slide and displace, and the polylactic acid-coated gelatin particles on the surface of the steel fiber will fall off and fill into the interface region between the steel fiber and the matrix. On the one hand, it will form a frictional resistance to increase the pull-out resistance of the steel fiber. On the other hand, the presence of polylactic acid-coated gelatin particles can make the stress more evenly distributed between the steel fiber and the concrete matrix, reducing the phenomenon of local stress concentration, thereby helping to improve the pull-out strength and toughness of the steel fiber. Meanwhile, the filling of polylactic acid-coated gelatin particles can also fill the gaps between the interfaces, further improving the tensile properties of the steel fiber.

[0010] According to some embodiments of the present application, the non-ionic surfactant comprises polysorbate.

[0011] In the present application, the polysorbate forms a molecular film adsorbed on the surface of the gelatin particles in the solution to maintain the stability of the gelatin particles. At the same time, the polysorbate changes the surface tension of the solution, affecting the diffusion rate and coagulation behavior of polylactic acid in the solution, thereby achieving the maintenance of the stability of small gelatin particles and the adjustment of the thickness of the polylactic acid coating layer, avoiding the oversize of the polylactic acid-coated gelatin microspheres on the surface of the steel fiber.

[0012] According to some embodiments of the present application, the preparation raw materials of the green high-strength concrete include, by weight: 850-1010 parts of steel slag stone, 850-1010 parts of steel slag sand, 100-200 parts of fly ash, and 50-70 parts of modified steel fiber.

[0013] According to some embodiments of the present application, the preparation raw materials of the green high-strength concrete further include: polycarboxylate superplasticizer and water.

[0014] According to the second aspect of the embodiments of the present application, a preparation method of the green high-strength concrete comprises the following steps:

[0015] S1. Mixing and dispersing the cement and the fly ash;

[0016] S2. Adding the steel slag stone, the steel slag sand and the modified steel fiber to the mixture obtained in step S1 and continuing to mix.

[0017] According to some embodiments of the present application, the preparation method of the modified steel fiber comprises:

[0018] A1. dispersing polylactic acid and adding non-ionic surfactant to obtain a mixed solution;

[0019] A2. adding gelatin to the mixed solution to obtain a polylactic acid coated gelatin microsphere solution;

[0020] A3. soaking steel fiber in the polylactic acid coated gelatin microsphere solution and solidifying to obtain modified steel fiber.

[0021] According to some embodiments of the present application, the method for preparing the modified steel fiber comprises:

[0022] A1. dispersing 100-200 parts of polylactic acid and adding 5-10 parts of non-ionic surfactant to obtain a mixed solution;

[0023] A2. adding 50-75 parts of gelatin to the mixed solution and reacting at 25-35℃ for 2-3h to obtain a polylactic acid coated gelatin microsphere solution;

[0024] A3. soaking steel fiber in the polylactic acid coated gelatin microsphere solution and solidifying at 40-60℃ for 6-8h to obtain modified steel fiber.

[0025] According to some embodiments of the present application, the particle size of the gelatin particles is 15-100 mesh.

[0026] The ultrasonic treatment helps to break the agglomeration between polylactic acid particles and promote their dispersion in the solution.

[0027] According to some embodiments of the present application, in step A2, the method for the reaction comprises ultrasonic reaction; the time for the ultrasonic reaction is 2-6h; the frequency for the ultrasonic reaction is 20kHz-100kHz.

[0028] In the present application, under the above ultrasonic treatment conditions, the agglomeration between polylactic acid particles is broken, which promotes their dispersion in the solution, so as to adjust the thickness of the polylactic acid coating layer within a suitable range.

[0029] According to some embodiments of the present application, in step A2, the pH value for the reaction is 6-7.

[0030] According to some embodiments of the present application, the step of dispersing polylactic acid comprises mixing polylactic acid and solvent, and the solvent comprises dimethyl sulfoxide and chloromethane.

[0031] The application of the green high-strength concrete according to the third aspect of the embodiments of the present application in the field of civil engineering. DETAILED DESCRIPTION

[0032] For better illustrating the object, technical scheme and advantages of the present application, the present application will be further described in combination with specific examples. Those skilled in the art should understand that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0033] The test methods used in the examples are all conventional methods unless otherwise specified; the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0034] Polylactic acid: (Alpha) Zhengzhou Alpha Chemical Co., Ltd., item number 26100-51-6;

[0035] Gelatin: Zhengzhou Wanbo Chemical Product Co., Ltd., gelatin with item number 8957.

[0036] Example 1

[0037] The present embodiment provides a green high-strength concrete and a preparation method thereof, in particular to:

[0038] The preparation method of the modified steel fiber is specifically:

[0039] A1. 100 parts of polylactic acid, 5 parts of non-ionic surfactant polysorbate and 150 parts of chloromethane are mixed to obtain a mixed solution;

[0040] A2. 60 parts of gelatin particles (gelatin particles are 15-100 mesh) are added to the mixed solution at pH 7, and the ultrasonic frequency is 80 kHz, the reaction is carried out at 35℃ for 3h to obtain a polylactic acid coated gelatin microsphere solution;

[0041] A3. The steel fiber is soaked in the polylactic acid coated gelatin microsphere solution, and then solidified at 40-60℃ for 6-8h to obtain a modified steel fiber.

[0042] The preparation method of the green high-strength concrete is:

[0043] B1. According to the weight parts, 3.2 parts of polycarboxylic acid type water reducing agent is dissolved in 221.4 parts of water, and stirred uniformly to form a water reducing agent solution; 498.2 parts of cement and 41.1 parts of fly ash are mixed to become a gel material,

[0044] B2. After mixing 945 parts of steel slag stone and 945 parts of steel slag sand into aggregate, and mixing 50 parts of modified steel fiber for 20 min at 60 rpm, and mixing water reducing agent solution and gel material for 2 min at 100 rpm, and finally mixing at 60 rpm, a concrete mortar is obtained; the mortar is poured into an oiled 150 mm x 150 mm x 150 mm plastic mold, compacted by shaking, and covered with plastic film on the opening of the mold to prevent water loss by evaporation, and after 24 h at a temperature of 20℃ and a relative humidity of 90%, the concrete module is removed from the mold and cured for 28 d under the same temperature and humidity conditions to obtain green high-strength concrete.

[0045] Example 2

[0046] The present example provides a green high-strength concrete and a preparation method thereof, and the difference between the present example and Example 1 is that in step B1, 1010 parts of steel slag stone, 850 parts of steel slag sand, 200 parts of fly ash, and 70 parts of modified steel fiber are used, and the remaining conditions are the same.

[0047] Example 3

[0048] The present example provides a green high-strength concrete and a preparation method thereof, and the difference between the present example and Example 1 is that in step B1, 1000 parts of steel slag stone, 850 parts of steel slag sand, 200 parts of fly ash, and 60 parts of modified steel fiber are used, and the remaining conditions are the same.

[0049] Example 4

[0050] The present example provides a green high-strength concrete and a preparation method thereof, and the difference between the present example and Example 1 is that in step B1, 1000 parts of steel slag stone, 1010 parts of steel slag sand, 200 parts of fly ash, and 70 parts of modified steel fiber are used, and the remaining conditions are the same.

[0051] Comparative Example 1

[0052] The present comparative example provides a green high-strength concrete and a preparation method thereof, and the difference between the present comparative example and Comparative Example 1 is that the steel fiber used is not modified, and the remaining conditions are the same.

[0053] Comparative Example 2

[0054] The present comparative example provides a green high-strength concrete and a preparation method thereof, and the difference between the present comparative example and Comparative Example 1 is that cetyltrimethylammonium chloride is used instead of polysorbate in Example 1, and the remaining conditions are the same.

[0055] Comparative Example 3

[0056] The present comparative example provides a green high-strength concrete and a preparation method thereof, and the difference between the present comparative example and Comparative Example 1 is that polyvinyl alcohol is used instead of polylactic acid in Example 1, and the remaining conditions are the same.

[0057] Test Example

[0058] The test example tests the parameters of the concrete obtained by the examples and comparative examples: concrete mechanical property test: the mechanical properties of the concrete modules prepared in each example are tested according to GB / T 50081-2002 “Standard for Testing Methods of Mechanical Properties of Ordinary Concrete”, and the test results are shown in Table 1:

[0059] The compressive strength of the concrete is tested and calculated according to Section 6 of the above standard;

[0060] The splitting tensile strength of the concrete is tested and calculated according to Section 9 of the above standard;

[0061] The test results are shown in Table 1.

[0062]

[0063] It can be found by comparing the examples that the compressive strength and splitting tensile strength of the concrete added with the modified steel fibers are improved. In Comparative Example 1, the steel fibers are not modified, so the steel fibers cannot improve the physical adhesion with the concrete matrix. At the same time, the unmodified steel fibers may not be uniformly distributed in the concrete, which can easily lead to stress concentration in the concrete, thereby reducing the splitting tensile strength of the concrete. In Comparative Example 2, the polysorbate is replaced by cetyltrimethylammonium chloride, which enhances the attraction between particles, thereby causing agglomeration between particles, resulting in poor dispersion of gelatin particles or steel fibers, affecting the overall interfacial bonding effect. In Comparative Example 3, polyvinyl alcohol is used instead of polylactic acid in Example 1. Because the polyethylene glycol on the surface of the modified steel fiber increases the hydrophobicity of the steel fiber, and due to steric hindrance, the adhesion between the steel fiber and the concrete interface is reduced, thereby reducing the strength of the concrete.

[0064] The above describes the present application in detail in combination with the examples, but the present application is not limited to the above examples. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present application.

Claims

1. A green high-strength concrete, characterized in that, The raw materials for preparing the green high-strength concrete include cement, and by weight 850-1010 parts of steel slag stone, 850-1010 parts of steel slag sand, 100-200 parts of fly ash and 50-70 parts of modified steel fiber. The modified steel fibers are prepared by the following method: A1. Disperse 100-200 parts of polylactic acid and add 5-10 parts of nonionic surfactant to obtain a mixture, wherein the nonionic surfactant includes polysorbate; A2. Add 50-75 parts of gelatin particles to the mixture and sonicate at 25-35°C for 2-3 hours to obtain a polylactic acid-coated gelatin microsphere solution. The pH value of the sonication reaction is 6-7 and the frequency of the sonication reaction is 20kHz-100kHz. A3. The steel fibers are immersed in the polylactic acid-coated gelatin microsphere solution and cured at 40~60℃ for 6~8h to obtain modified steel fibers.

2. The green high-strength concrete according to claim 1, characterized in that, The gelatin particles have a particle size of 15-100 mesh.

3. The green high-strength concrete according to claim 1, characterized in that, In step A1, the dispersion of polylactic acid includes mixing polylactic acid with a solvent, wherein the solvent includes dimethyl sulfoxide and methane chloride.

4. A method for preparing green high-strength concrete as described in claim 1, characterized in that, Includes the following steps: S1. Mix and disperse the cement and the fly ash; S2. Add the steel slag, steel slag sand and modified steel fibers to the mixture obtained in step S1 and continue mixing.

5. The application of the green high-strength concrete as described in claim 1 in the field of civil engineering.

Images