Preparation method and layered pouring process of environment-friendly high-toughness concrete

Abstract

The invention relates to a preparation method of environment-friendly high-toughness concrete and a layered pouring process, and belongs to the technical field of building materials. The preparation method comprises the following steps: firstly, modifying steel fibers by using a self-made quaternization corrosion inhibitor, sodium silicate and an ethanol solution, and then stirring the modified steel fibers, Portland cement, rubber, natural sand and first-grade gravel to obtain a prefabricated material; finally, a polycarboxylic acid water reducing agent, an air entraining agent and an expanding agent are prepared into a solution, the solution is poured into the prefabricated material, stirring and mixing are conducted, and the environment-friendly high-toughness concrete is obtained.The modified steel fiber prepared through the preparation method has a better corrosion inhibition effect and has good bonding performance with the concrete; the mechanical property of the finally prepared concrete is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and in particular relates to a preparation method and a layered pouring process of environmentally friendly high-toughness concrete. Background Art

[0002] As one of the most important civil engineering materials in contemporary times, concrete has the advantages of strong plasticity, good bond strength, good economy, high safety, good fire resistance, wide application range and good durability. It is widely used in civil engineering, shipbuilding, machinery industry, marine development and geothermal engineering. However, this traditional material also has some inherent disadvantages, such as low tensile strength, poor ductility, poor volume stability, etc., which limit the application of conventional concrete in fields with higher requirements.

[0003] Steel fiber-modified concrete is a new type of multiphase composite material formed by adding short steel fibers to ordinary concrete. It can effectively improve the tensile strength of concrete and hinder the formation and expansion of concrete cracks. However, steel fibers may be affected by corrosion during long-term use, thereby affecting the mechanical properties and durability of concrete. Based on this, the present invention provides a preparation method and layered casting process for environmentally friendly high-toughness concrete. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and a layered pouring process of environmentally friendly high-toughness concrete, so as to solve the problems mentioned in the above background technology.

[0005] The purpose of the present invention can be achieved through the following technical solutions: The method for preparing environmentally friendly high-toughness concrete comprises the following steps: The first step is to mix 2-imidazoline, allyl methyl sulfide, imidazole hydrochloride, and toluene in a four-necked flask, install a condenser and a thermometer, start mechanical stirring, and react at a temperature of 80-100°C for 6-10 hours. After the reaction is completed, a saturated sodium chloride solution is added to the three-necked flask for washing, and the organic layer is separated with a separatory funnel. The organic layer is rotary evaporated to remove the solvent and then subjected to silica gel column chromatography to obtain a corrosion inhibitor; In the second step, the corrosion inhibitor, propyl chloride and acetonitrile are mixed in a four-necked flask, a condenser and a thermometer are installed, mechanical stirring is started, and the mixture is reacted at a temperature of 20 to 50° C. for 16 to 24 hours. After the reaction is completed, the solvent is removed by rotary evaporation to obtain a quaternized corrosion inhibitor; Step 3: Dissolve the quaternized corrosion inhibitor and sodium silicate in ethanol solution and spray them on the surface of the steel fiber, then drain naturally and dry in an oven to constant weight to obtain modified steel fiber; Step 4: Pour Portland cement, modified steel fiber, rubber, natural sand and first-grade crushed stone into a mixer and stir and mix them evenly to obtain prefabricated material; Step 5: Dissolve the polycarboxylate water reducer, air entraining agent and expansion agent in water and pour the solution into a mixer filled with prefabricated materials to mix and obtain environmentally friendly high-toughness concrete.

[0006] Furthermore, the rubber is waste tire rubber particles, the particle size specification of the first-grade crushed stone is 19-31.5 mm, the air entraining agent is AE-360 air entraining agent, and the expansion agent is UEA expansion agent.

[0007] Furthermore, the amount ratio of 2-imidazoline, allyl methyl sulfide, imidazole hydrochloride and toluene used in the first step is 0.1 mol: 0.1-0.11 mol: 0.01-0.03 mol: 80-100 mL.

[0008] Furthermore, the amount ratio of the corrosion inhibitor, propyl chloride and acetonitrile used in the second step is 0.06 mol: 0.06-0.8 mol: 60-80 mL.

[0009] Furthermore, the volume fraction of the ethanol solution used in the third step is 30-80%, and the usage ratio of the quaternized corrosion inhibitor, sodium silicate, ethanol solution, and steel fiber is 3-6 g: 8-12 g: 80-100 mL: 160-180 g.

[0010] Preferably, the temperature of the oven in the third step is set to 60-70°C.

[0011] Furthermore, the mass ratio of silicate cement, modified steel fiber, rubber, natural sand, primary crushed stone, polycarboxylic acid water reducer, air entraining agent, expansion agent and water is 380-420:60-80:5-25:600-850:910-1200:3.5-4.5:0.2-0.3:20-30:160-180.

[0012] Preferably, the prefabricated materials are stirred and mixed at a rotation speed of 300-400 rpm and for a stirring time of 5-30 min in the fourth step.

[0013] Preferably, in the fifth step, the rotation speed of the mixing of the environmentally friendly high-toughness concrete is 250-350 rpm, and the mixing time is 3-4 minutes.

[0014] Layered pouring process of environmentally friendly high-toughness concrete: Start pouring from the short side of the specimen mold along the long side layer by layer. After each layer of concrete is poured, use a trowel to smooth it along the long side of the mold, then vibrate it to make it dense and pour the next layer of concrete, ensuring that the pouring is completed before the previous layer of concrete begins to set. Repeat this step until the concrete pouring is completed.

[0015] Beneficial effects of the present invention: (1) The present invention uses 2-imidazoline and allyl methyl sulfide as raw materials, utilizes the imino group of 2-imidazoline and the carbon-carbon double bond structure of allyl methyl sulfide to undergo Michael addition reaction under the condition of imidazole hydrochloride as catalyst to obtain a corrosion inhibitor, and then uses the corrosion inhibitor and propyl chloride as raw materials, utilizes the halogen atom of propyl chloride and the tertiary amine structure in the corrosion inhibitor to undergo quaternary ammonium salt reaction to obtain a quaternized corrosion inhibitor. 2-Imidazolline is a commonly used iron-based corrosion inhibitor. The present invention introduces a long sulfide chain into it and quaternizes it, improves its adsorption effect by converting the nitrogen atom adsorption site into a pentavalent cation and introduces additional sulfur atom adsorption sites, effectively improving the adsorption effect of the prepared quaternized corrosion inhibitor on the iron-based surface, and has better corrosion inhibition performance than 2-imidazoline.

[0016] (2) The preparation method of the present invention uses waste tire rubber particles as the raw material of concrete materials, which is economical, environmentally friendly and in line with the concept of sustainable development. In addition, the surface of the modified steel fiber of the present invention is attached with a quaternary ammonium corrosion inhibitor with a quaternary ammonium salt structure, which carries a positive charge after ionization in concrete. It can improve the binding effect between the modified steel fiber and the silicate anions in sodium silicate through the charge complementary effect, promote the uniform deposition of the silicate gel layer on the surface of the steel fiber, and thus improve the interfacial bonding performance between the steel fiber and silicate concrete, and improve the effect of steel fiber on improving the mechanical properties of concrete.

[0017] (3) The directional steel fiber reinforced recycled concrete of the present invention uses a layered casting process, which can ensure that the concrete is fully dense during the casting process, reduce microcracks and voids inside the concrete, and improve the compressive strength and crack resistance of the concrete after solidification. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 making any creative efforts shall fall within the scope of protection of the present invention. Example 1

[0019] A modified steel fiber is prepared by the following steps: The first step is to mix 0.1 mol of 2-imidazoline, 0.1 mol of allyl methyl sulfide, 0.01 mol of imidazole hydrochloride, and 80 mL of toluene in a four-necked flask, install a condenser and a thermometer, start mechanical stirring, and react at a temperature of 80°C for 10 hours. After the reaction is completed, a saturated sodium chloride solution is added to the three-necked flask for washing, and the organic layer is separated with a separatory funnel. The organic layer is rotary evaporated to remove the solvent and then subjected to silica gel column chromatography to obtain a corrosion inhibitor; In the second step, 0.06 mol of corrosion inhibitor, 0.06 mol of propyl chloride and 60 mL of acetonitrile were mixed in a four-necked flask, a condenser and a thermometer were installed, mechanical stirring was started, and the reaction was carried out at a temperature of 20°C for 24 hours. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a quaternized corrosion inhibitor; In the third step, 3 g of quaternary ammonium corrosion inhibitor and 8 g of sodium silicate were dissolved in 80 mL of 30% by volume ethanol solution and sprayed on the surface of 160 g of steel fiber. The steel fiber was then naturally drained and dried in an oven at 60°C to constant weight to obtain modified steel fiber. Example 2

[0020] A modified steel fiber is prepared by the following steps: The first step is to mix 0.1 mol 2-imidazoline, 0.105 mol allyl methyl sulfide, 0.02 mol imidazole hydrochloride, and 90 mL toluene in a four-necked flask, install a condenser and a thermometer, start mechanical stirring, and react at a temperature of 90°C for 8 hours. After the reaction is completed, a saturated sodium chloride solution is added to the three-necked flask for washing, and the organic layer is separated with a separatory funnel. The organic layer is rotary evaporated to remove the solvent and then subjected to silica gel column chromatography to obtain a corrosion inhibitor; In the second step, 0.06 mol of corrosion inhibitor, 0.07 mol of propyl chloride and 70 mL of acetonitrile were mixed in a four-necked flask, a condenser and a thermometer were installed, mechanical stirring was started, and the reaction was carried out at a temperature of 35°C for 20 hours. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a quaternized corrosion inhibitor; The third step is to dissolve 4.5g of quaternary ammonium corrosion inhibitor and 10g of sodium silicate in 90mL of 55% by volume ethanol solution and spray them on the surface of 170g of steel fiber. Then, drain it naturally and bake it in an oven at 65°C to constant weight to obtain modified steel fiber. Example 3

[0021] A modified steel fiber is prepared by the following steps: The first step is to mix 0.1 mol 2-imidazoline, 0.11 mol allyl methyl sulfide, 0.03 mol imidazole hydrochloride, and 100 mL toluene in a four-necked flask, install a condenser and a thermometer, start mechanical stirring, and react at a temperature of 100 ° C for 6 hours. After the reaction is completed, a saturated sodium chloride solution is added to the three-necked flask for washing, and the organic layer is separated with a separatory funnel. The organic layer is rotary evaporated to remove the solvent and then subjected to silica gel column chromatography to obtain a corrosion inhibitor; In the second step, 0.06 mol of corrosion inhibitor, 0.08 mol of propyl chloride and 80 mL of acetonitrile were mixed in a four-necked flask, a condenser and a thermometer were installed, mechanical stirring was started, and the reaction was carried out at a temperature of 50°C for 16 hours. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a quaternized corrosion inhibitor; In the third step, 6 g of quaternary ammonium corrosion inhibitor and 12 g of sodium silicate were dissolved in 100 mL of 30% ethanol solution and sprayed on the surface of 180 g of steel fiber. The mixture was then naturally drained and dried in an oven at 70°C to constant weight to obtain modified steel fiber.

[0022] Comparative Example 1 6 g of 2-imidazoline and 12 g of sodium silicate were dissolved in 100 mL of 30% by volume ethanol solution and sprayed on the surface of 180 g of steel fiber. The mixture was then naturally drained and dried in an oven to constant weight to obtain modified steel fiber.

[0023] Test Example 1 Weigh equal masses of the modified steel fibers and unmodified steel fibers obtained in Examples 1-3 and Comparative Example 1, and record the weight as W. Add the modified steel fibers of each component and an equal amount of unmodified steel fibers to a 1 mol / L hydrochloric acid solution and soak for 48 hours at room temperature. Then take them out and rinse the steel fibers three times with clean water. Use a soft brush to remove the corrosion products covering the surface of the steel fibers. After washing, place them in an oven and dry them to constant weight. After weighing, calculate the corrosion mass change ΔW in each embodiment. The untreated modified steel fibers are used as blank controls. Calculate the corrosion inhibition rate η of the modified steel fibers of each component = (ΔW 空白对照 -△W) / △W 空白对照 , the data results are shown in Table 1: Table 1 project Corrosion inhibition rate% Example 1 92.79 Example 2 93.14 Example 3 93.26 Comparative Example 1 88.13 It can be seen from Table 1 that the corrosion resistance of the modified steel fibers obtained in Examples 1-3 after treatment with the quaternized corrosion inhibitor of the present invention is greatly improved compared with the modified steel fibers treated with conventional corrosion inhibitors, indicating that the quaternized corrosion inhibitor prepared by the present invention has a better corrosion inhibition effect. Example 4

[0024] The method for preparing environmentally friendly high-toughness concrete comprises the following steps: The first step is to pour 380 parts of Portland cement, 60 parts of modified steel fiber obtained in Example 1, 5 parts of waste tire rubber particles, 600 parts of natural sand, and 910 parts of first-grade gravel with a particle size of 19 mm into a mixer and stir at a speed of 300 rpm for 30 minutes to obtain a prefabricated material; In the second step, 3.5 parts of polycarboxylate water reducer, 0.2 parts of AE-360 air entraining agent, and 20 parts of UEA expansion agent were dissolved in 160 parts of water by mass, and the solution was poured into a mixer filled with prefabricated materials and stirred at a speed of 250 rpm for 4 minutes to obtain environmentally friendly high-toughness concrete.

[0025] The concrete was poured using a layered pouring process, starting from the short side of the specimen mold and pouring layer by layer along the long side. After each layer of concrete was poured, it was smoothed along the long side of the mold with a trowel, and then vibrated to compact it and poured the next layer of concrete, ensuring that the pouring was completed before the previous layer of concrete began to set. This step was repeated until the concrete pouring was completed. Example 5

[0026] The method for preparing environmentally friendly high-toughness concrete comprises the following steps: The first step is to pour 400 parts of Portland cement, 70 parts of modified steel fiber obtained in Example 2, 15 parts of waste tire rubber particles, 850 parts of natural sand, and 1200 parts of first-grade gravel with a particle size of 25.5 mm into a mixer and stir at a speed of 350 rpm for 17.5 minutes to obtain a prefabricated material; In the second step, 4 parts of polycarboxylate water reducer, 0.25 parts of AE-360 air entraining agent, and 25 parts of UEA expansion agent were dissolved in 170 parts of water by mass, and the solution was poured into a mixer filled with prefabricated materials and stirred at a speed of 300 rpm for 3.5 minutes to obtain environmentally friendly high-toughness concrete.

[0027] The concrete was poured using a layered pouring process, starting from the short side of the specimen mold and pouring layer by layer along the long side. After each layer of concrete was poured, it was smoothed along the long side of the mold with a trowel, and then vibrated to compact it and poured the next layer of concrete, ensuring that the pouring was completed before the previous layer of concrete began to set. This step was repeated until the concrete pouring was completed.

[0028] Example 6 The method for preparing environmentally friendly high-toughness concrete comprises the following steps: The first step is to pour 420 parts of Portland cement, 80 parts of modified steel fiber obtained in Example 3, 25 parts of waste tire rubber particles, 725 parts of natural sand, and 1055 parts of first-grade gravel with a particle size of 31.5 mm into a mixer and stir at a speed of 400 rpm for 5 minutes to obtain a prefabricated material; In the second step, 4.5 parts of polycarboxylate water reducer, 0.3 parts of AE-360 air entraining agent, and 30 parts of UEA expansion agent were dissolved in 180 parts of water by mass, and the solution was poured into a mixer filled with prefabricated materials and stirred at a speed of 350 rpm for 3 minutes to obtain environmentally friendly high-toughness concrete.

[0029] The concrete was poured using a layered pouring process, starting from the short side of the specimen mold and pouring layer by layer along the long side. After each layer of concrete was poured, it was smoothed along the long side of the mold with a trowel, and then vibrated to compact it and poured the next layer of concrete, ensuring that the pouring was completed before the previous layer of concrete began to set. This step was repeated until the concrete pouring was completed. Comparative Example 2

[0030] The method for preparing environmentally friendly high-toughness concrete comprises the following steps: The first step is to pour 420 parts of Portland cement, 80 parts of modified steel fiber obtained in Example 3, 25 parts of waste tire rubber particles, 725 parts of natural sand, and 1055 parts of first-grade gravel with a particle size of 31.5 mm into a mixer and stir at a speed of 400 rpm for 5 minutes to obtain a prefabricated material; In the second step, 4.5 parts of polycarboxylate water reducer, 0.3 parts of AE-360 air entraining agent, and 30 parts of UEA expansion agent were dissolved in 180 parts of water by mass, and the solution was poured into a mixer filled with prefabricated materials and stirred at a speed of 350 rpm for 3 minutes to obtain environmentally friendly high-toughness concrete.

[0031] The concrete was poured using a layered pouring process, starting from the short side of the specimen mold and pouring layer by layer along the long side. After each layer of concrete was poured, it was smoothed along the long side of the mold with a trowel, and then vibrated to compact it and poured the next layer of concrete, ensuring that the pouring was completed before the previous layer of concrete began to set. This step was repeated until the concrete pouring was completed.

[0032] Test Example 2 After curing for 28 days at a temperature of 20±2°C and a humidity of ≥95%, the concrete in Examples 4-6 and Comparative Example 2 were tested for compressive strength and tensile strength according to the national standard GB / T50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". The results are shown in Table 2: Table 2 project Compressive strength / MPa Tensile strength / MPa Example 4 47.46 6.32 Example 5 48.17 6.96 Example 6 47.87 6.63 Comparative Example 2 42.25 4.38 As can be seen from Table 2, the environmentally friendly high-toughness concrete of Examples 4-6 of the present invention has excellent compressive strength and tensile strength, while the compressive strength and tensile strength of the environmentally friendly high-toughness concrete in Comparative Example 2 are weaker than those of the concrete in Examples 4-6. The reason is that the quaternary ammonium corrosion inhibitor of the present invention is not used to modify the steel fiber, which leads to the weakening of the deposition effect of sodium silicate on the surface of the steel fiber, thereby affecting the bonding performance between the steel fiber and the concrete, and further affecting the improvement effect of the steel fiber on the performance of the concrete. In summary, the environmentally friendly high-toughness concrete of the present invention has good mechanical properties, and the internal steel fiber is not easily corroded, and can be widely used in the construction field.

[0033] The above is a detailed introduction to the preparation method and layered pouring process of the environmentally friendly high-toughness concrete provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best way, and also enables any technician in this field to practice the present invention, including the manufacture and use of any device or system, and the implementation of any combination method. It should be pointed out that for ordinary technicians in this technical field, the present invention can also be improved and modified without departing from the principles of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention can be combined with each other in any way. The fact that these combinations are not exhaustively described in this specification is simply for the sake of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for preparing environmentally friendly high-toughness concrete, characterized in that: The following steps are involved: Modification of steel fiber: 2-imidazoline, allyl methyl sulfide, imidazole hydrochloride, and toluene are mixed and reacted at a temperature of 90-100°C to obtain a corrosion inhibitor. The corrosion inhibitor is then mixed with propyl chloride and acetonitrile and reacted at a temperature of 20-50°C to obtain a quaternized corrosion inhibitor. The quaternized corrosion inhibitor and sodium silicate are dissolved in an ethanol solution and sprayed on the surface of the steel fiber. The modified steel fiber is obtained after draining and drying. Preparation of environmentally friendly high-toughness concrete: Portland cement, modified steel fiber, rubber, natural sand, and first-grade crushed stone are mixed to obtain prefabricated materials, and then polycarboxylic acid water reducer, air entraining agent, and expansion agent are dissolved in water and poured into the prefabricated materials and stirred to obtain environmentally friendly high-toughness concrete.

2. The method for preparing environmentally friendly high-toughness concrete according to claim 1, characterized in that: Furthermore, the rubber is waste tire rubber particles, and the particle size specification of the first-grade gravel is 19-31.5 mm.

3. The method for preparing environmentally friendly high-toughness concrete according to claim 1, characterized in that: The air entraining agent is AE-360 air entraining agent, and the expansion agent is UEA expansion agent.

4. The method for preparing environmentally friendly high-toughness concrete according to claim 1, characterized in that: The usage ratio of 2-imidazoline, allyl methyl sulfide, imidazole hydrochloride and toluene is 0.1 mol: 0.1-0.11 mol: 0.01-0.03 mol: 80-100 mL.

5. The method for preparing environmentally friendly high-toughness concrete according to claim 1, characterized in that: The usage ratio of corrosion inhibitor, propyl chloride and acetonitrile is 0.06 mol: 0.06-0.8 mol: 60-80 mL.

6. The method for preparing environmentally friendly high-toughness concrete according to claim 1, characterized in that: The volume fraction of the ethanol solution is 30-80%, and the dosage ratio of the quaternized ammonium corrosion inhibitor, sodium silicate, ethanol solution and steel fiber is 3-6g: 8-12g: 80-100mL: 160-180g.

7. The method for preparing environmentally friendly high-toughness concrete according to claim 1, characterized in that: The mass ratio of silicate cement, modified steel fiber, rubber, natural sand, primary crushed stone, polycarboxylic acid water reducer, air entraining agent, expansion agent and water is 380-420: 60-80: 5-25: 600-850: 910-1200: 3.5-4.5: 0.2-0.3: 20-30: 160-180.

8. The method for preparing environmentally friendly high-toughness concrete according to claim 1, characterized in that: The prefabricated materials are stirred and mixed at a speed of 300-400 rpm, and for a time of 5-30 min.

9. The method for preparing environmentally friendly high-toughness concrete according to claim 1, characterized in that: The speed condition for mixing environmentally friendly high-toughness concrete is 250-350rpm, and the mixing time condition is 3-4min.

10. A layered pouring process for environmentally friendly high-toughness concrete obtained by the preparation method according to any one of claims 1 to 9, characterized in that: Start pouring from the short side of the specimen mold along the long side layer by layer. After each layer of concrete is poured, use a trowel to smooth it along the long side of the mold, then vibrate it to make it dense and pour the next layer of concrete, ensuring that the pouring is completed before the previous layer of concrete begins to set. Repeat this step until the concrete pouring is completed.