Ultrafine limestone powder cement concrete and preparation method thereof

Abstract

The present application relates to the field of cement concrete, and specifically discloses a limestone ultrafine powder cement concrete and its preparation method. It comprises the following raw materials in parts by weight: 1100-1200 parts of coarse aggregate, 550-650 parts of fine aggregate, 160-210 parts of cement, 4-7 parts of water reducer, 100-140 parts of water, 140-160 parts of admixture, wherein the admixture comprises ultrafine limestone powder, fly ash and mineral powder, wherein the weight ratio of the ultrafine limestone powder, fly ash and mineral powder is 5:3:2, and 60-120 parts of stabilizer, wherein the stabilizer comprises a load agent, a binder and a reinforcing agent, wherein the weight ratio of the load agent, the binder and the reinforcing agent is 3:1:2. The cement concrete of the present application has the advantage of reducing the adverse effects of the addition of ultrafine limestone powder on the chloride ion diffusion resistance of the concrete.

Description

Technical Field

[0001] The present application relates to the field of cement concrete, and more specifically, to an ultrafine limestone powder cement concrete and a preparation method thereof. Background Art

[0002] Concrete is the building material with the largest usage and the widest range of applications. In the production process of concrete, using fly ash and other materials as concrete admixtures can not only improve the working performance of concrete and enhance its durability, but also reduce the amount of cement used and reduce project costs.

[0003] A large amount of limestone powder will be produced in the process of producing machine-made sand and gravel. If the limestone powder is disposed of by open-air stacking and landfill, it will not only pollute the environment, but also have adverse effects on the lives of surrounding residents.

[0004] Using ultrafine limestone powder as an admixture to replace part of the cement can reduce the amount of cement used, slow down the hydration rate of the cementitious material, and improve the working performance of the concrete. However, the addition of ultrafine limestone powder increases the total porosity, resulting in poor resistance of the concrete to chloride ion diffusion. Summary of the Invention

[0005] In order to reduce the adverse effects of ultrafine limestone powder on the chloride ion diffusion resistance of concrete, the present application provides an ultrafine limestone powder cement concrete and a preparation method thereof.

[0006] In a first aspect, the present application provides a limestone ultrafine powder cement concrete, which adopts the following technical solution:

[0007] Disclosed is an ultrafine limestone powder cement concrete, comprising the following raw materials in parts by weight: 1,100-1,200 parts of coarse aggregate, 550-650 parts of fine aggregate, 160-210 parts of cement, 4-7 parts of a water reducer, 100-140 parts of water, 140-160 parts of an admixture, wherein the admixture comprises ultrafine limestone powder, fly ash and mineral powder in a weight ratio of 5:3:2, and 60-120 parts of a stabilizer, wherein the stabilizer comprises a load, a binder and a reinforcing agent in a weight ratio of 3:1:2.

[0008] By adopting the above technical solution, the reinforcing agent is attached to the loading agent through the binder. The reinforcing agent improves the bonding strength between the loading agent and other raw materials, and at the same time attracts chloride ions, so that the chloride ions penetrate inward from the stabilizer. During the penetration process, the chloride ions enter the loading agent through the reinforcing agent and the binder, so that the chloride ions are temporarily bound and cannot continue to penetrate into the concrete, thereby reducing the amount of chloride ions that continue to penetrate deep into the concrete at the same time, thereby effectively improving the concrete's resistance to chloride ion penetration.

[0009] Preferably, the supporting agent comprises ceramic powder, calcium hydroxide and red mud, and the weight ratio of the ceramic powder, calcium hydroxide and red mud is 3:1:1.

[0010] By adopting the above technical solution, red mud is used as a bonding material to combine ceramic powder and calcium hydroxide into a whole. The ceramic powder plays the main role of supporting the skeleton. Chloride ions are combined with calcium hydroxide and consumed, effectively reducing the chloride ions that penetrate into the concrete.

[0011] Preferably, the loading agent is prepared by the following steps: ceramic powder and calcium hydroxide are mixed, red mud is added thereto, and granulated by a disc to form particles, and the particles are then dried to obtain the loading agent.

[0012] By adopting the above technical solution, red mud is used as a bonding material, so that ceramic powder is combined with calcium hydroxide. The ceramic powder effectively improves the anti-penetration and compressive strength of concrete, and the calcium hydroxide combines with chloride ions to consume chloride ions.

[0013] Preferably, the binder comprises chitosan solution and sodium hydroxide solution, and the weight ratio of the chitosan solution to the sodium hydroxide solution is 4:1.

[0014] By adopting the above technical solution, using chitosan solution as an adhesive and sodium hydroxide solution as a dissolving agent, the reinforcing agent is partially dissolved and then infiltrated into the loading agent, and the remaining part is bonded by the chitosan solution, thereby effectively improving the connection strength of the reinforcing agent on the loading agent.

[0015] Preferably, the reinforcing agent comprises straw fiber, triethanolamine and rubber powder, and the weight ratio of the straw fiber, triethanolamine and rubber powder is 2:4:1.

[0016] By adopting the above technical solution, triethanolamine is used to improve the compatibility of straw fiber and rubber powder, so that the straw fiber and rubber powder are combined, effectively increasing the capillary pores and air-entraining pores of cement concrete, especially the capillary pores and air-entraining pores located near the stabilizer, and the pore structure becomes uniform. Chloride ions are combined with the loading agent from the capillary pores and air-entraining pores through the straw fiber and chitosan bonding layer, thereby consuming the chloride ions.

[0017] Preferably, the reinforcing agent is prepared by the following steps: firstly, the straw fiber and triethanolamine are mixed and stirred evenly, then rubber powder is added and the mixture is stirred and mixed continuously, and then the mixture is dried after stirring for a period of time to prepare the reinforcing agent.

[0018] By adopting the above technical solution, the straw fiber is first surface-modified using triethanolamine, and then the rubber powder is loaded on the surface of the straw fiber. The straw fiber loaded with rubber powder is dried and solidified to improve the bonding strength of the rubber powder on the surface of the straw fiber.

[0019] Preferably, the stabilizer is prepared by the following steps: firstly, mixing the enhancer with sodium hydroxide solution, then adding chitosan solution and mixing, and finally adding the loading agent and mixing evenly, and drying to prepare the stabilizer.

[0020] By adopting the above technical solution, the reinforcing agent is first partially dissolved, so that the lignin and cellulose contained in the reinforcing agent are dissolved in the sodium hydroxide solution and penetrate into the loading agent during the mixing process with the loading agent, thereby enhancing the performance of the loading agent. Then, the remaining part is bonded to the loading agent through the chitosan solution to prepare the stabilizer.

[0021] In a second aspect, the present application provides a method for preparing ultrafine limestone powder cement concrete, which adopts the following technical solution:

[0022] A preparation method of ultrafine limestone powder cement concrete comprises the following steps: mixing coarse aggregate, fine aggregate, cement, admixture and stabilizer and stirring them uniformly; then adding water reducer and water and mixing and stirring them uniformly to prepare cement concrete.

[0023] By adopting the above technical solution, cement concrete can be prepared by simply mixing the raw materials, the operation is simple and the product is easy to obtain.

[0024] In summary, this application has the following beneficial effects:

[0025] 1. This application uses a binder to make the reinforcing agent adhere to the loading agent. Chloride ions penetrate through the reinforcing agent and the binder to reach the loading agent and combine with the loading agent, thereby blocking the penetration of chloride ions, effectively curbing the further penetration of chloride ions and reducing the adverse effects of chloride ion penetration on concrete performance.

[0026] 2. In this application, triethanolamine is preferably used to modify the surface of the straw fiber and combine it with rubber powder, which effectively increases the capillary pores and air-entraining pores of the cement concrete near the stabilizer, thereby guiding the chloride ions to combine with the stabilizer and reducing the erosion of other components.

[0027] 3. In this application, it is preferred to dissolve and mix straw fiber with sodium hydroxide, so that part of the lignin and cellulose dissolves and penetrates into the loading agent and combines with the loading agent to increase the strength of the loading agent. Then, the straw fiber is combined with the loading agent through the chitosan solution, so that the surface stability of the loading agent is further improved. DETAILED DESCRIPTION

[0028] In this application: the coarse aggregate is continuously graded crushed stone with a particle size of 5 to 25 mm; the fine aggregate is river sand with a particle size of 0.075 to 5 mm; the cement is PⅡ42.5 silicate cement; the water reducer is a polycarboxylate water reducer; water; the ultrafine limestone powder is 500 mesh; the fly ash is Class I fly ash; the mineral powder is S95 grade mineral powder; the ceramic powder is 1250 mesh, purchased from the market; the calcium hydroxide is industrial grade, purchased from the market; the red mud is the Guangxi Pingguo aluminum red mud; chitosan solution: weigh 1.0 g of chitosan and add it to 500 mL of clean water. In a beaker, add 400 mL of water and 12.5 mL of 20% HNO3 solution. Under stirring conditions, add the weighed chitosan into the beaker and stir until the chitosan is completely dissolved. Transfer the dissolved chitosan solution to a 1000 mL volumetric flask and dilute it with water to the mark to obtain a 1.0 g / L chitosan solution; the sodium hydroxide solution is a sodium hydroxide solution with a mass fraction of 2%; the straw fiber is wheat straw fiber powder with a mesh size of 20 mesh; triethanolamine is industrial grade and purchased from the market; the rubber powder has a mesh size of 80 mesh and is purchased from the market.

[0029] The present application is further described in detail below with reference to the embodiments.

[0030] Preparation Example

[0031] Preparation example of loading agent

[0032] Preparation Example 1

[0033] This preparation example provides a loading agent, which is prepared by the following steps: combining 3 kg of ceramic powder and 1 kg of calcium hydroxide, then adding 1 kg of red mud and forming particles by disk granulation. The particle size is 5 mm, and the particles are then dried at 100°C for 20 minutes to prepare the loading agent.

[0034] Preparation example of enhancer

[0035] Preparation Example 2

[0036] This preparation example provides a reinforcing agent, which is prepared by the following steps: first, 2 kg of straw fiber and 4 kg of triethanolamine are mixed and stirred evenly, then 1 kg of rubber powder is added and continued to be stirred and mixed, after stirring for 3 hours, the reinforcing agent is dried at 60°C for 2 hours.

[0037] Preparation example of stabilizer

[0038] Preparation Example 3

[0039] This preparation example provides a stabilizer, which is prepared by the following steps: first, 1 kg of the enhancer prepared in Preparation Example 2 is mixed and stirred evenly with 0.4 kg of sodium hydroxide solution, then 1.6 kg of chitosan solution is added and stirred evenly, and finally 3 kg of the load agent prepared in Preparation Example 1 is added and mixed evenly, and then dried at 60°C for 2 h to prepare the stabilizer.

[0040] Preparation Example 4

[0041] This preparation example provides a stabilizer, which is prepared by the following steps: 1 kg of the enhancer prepared in Preparation Example 2 and 3 kg of the loading agent prepared in Preparation Example 1 are evenly mixed, and then dried at 60° C. for 2 h to prepare the stabilizer.

[0042] Preparation Example 5

[0043] This preparation example provides a stabilizer, which is prepared by the following steps: first, 1 kg of the enhancer prepared in Preparation Example 2 is mixed with 0.4 kg of sodium hydroxide solution and stirred evenly, then 1.6 kg of chitosan solution is added and mixed and stirred evenly, and then dried at 60°C for 2 hours to prepare the stabilizer.

[0044] Preparation Example 6

[0045] This preparation example provides a stabilizer, which is prepared by the following steps: 0.4 kg of sodium hydroxide solution and 1.6 kg of chitosan solution are mixed and stirred evenly, and finally 3 kg of the loading agent prepared in Preparation Example 1 is added and mixed evenly, and then dried at 60° C. for 2 h to prepare the stabilizer.

[0046] Example

[0047] Example 1

[0048] The embodiment of the present application provides a cement concrete, which is prepared by the following steps: mixing 1100 kg of coarse aggregate, 550 kg of fine aggregate, 160 kg of cement, 70 kg of ultrafine limestone powder, 42 kg of fly ash, 28 kg of mineral powder and 60 kg of the stabilizer prepared in Preparation Example 3, and then adding 4 kg of water reducer and 100 kg of water and stirring and mixing uniformly to prepare the cement concrete.

[0049] Example 2

[0050] The embodiment of the present application provides a cement concrete, which is prepared by the following steps: mixing 1150 kg of coarse aggregate, 600 kg of fine aggregate, 185 kg of cement, 75 kg of ultrafine limestone powder, 45 kg of fly ash, 30 kg of mineral powder and 80 kg of the stabilizer prepared in Preparation Example 3, and then adding 5.5 kg of water reducer and 120 kg of water and stirring and mixing uniformly to prepare the cement concrete.

[0051] Example 3

[0052] The embodiment of the present application provides a cement concrete, which is prepared by the following steps: mixing 1200 kg of coarse aggregate, 650 kg of fine aggregate, 210 kg of cement, 80 kg of ultrafine limestone powder, 48 kg of fly ash, 32 kg of mineral powder and 100 kg of the stabilizer prepared in Preparation Example 3, and then adding 7 kg of water reducer and 140 kg of water and stirring and mixing uniformly to prepare the cement concrete.

[0053] Comparative Example

[0054] Comparative Example 1

[0055] The comparative example of the present application provides a cement concrete, which is prepared by the following steps: mixing 1150 kg of coarse aggregate, 600 kg of fine aggregate, 185 kg of cement, 75 kg of ultrafine limestone powder, 45 kg of fly ash, 30 kg of mineral powder and 80 kg of the stabilizer prepared in Preparation Example 4, and then adding 5.5 kg of water reducer and 120 kg of water and stirring and mixing uniformly to prepare the cement concrete.

[0056] Comparative Example 2

[0057] The comparative example of the present application provides a cement concrete, which is prepared by the following steps: mixing 1150 kg of coarse aggregate, 600 kg of fine aggregate, 185 kg of cement, 75 kg of ultrafine limestone powder, 45 kg of fly ash, 30 kg of mineral powder and 80 kg of the stabilizer prepared in Preparation Example 5, and then adding 5.5 kg of water reducer and 120 kg of water and stirring and mixing uniformly to prepare the cement concrete.

[0058] Comparative Example 3

[0059] The comparative example of the present application provides a cement concrete, which is prepared by the following steps: mixing 1150 kg of coarse aggregate, 600 kg of fine aggregate, 185 kg of cement, 75 kg of ultrafine limestone powder, 45 kg of fly ash, 30 kg of mineral powder and 80 kg of the stabilizer prepared in Preparation Example 6, and then adding 5.5 kg of water reducer and 120 kg of water and stirring and mixing uniformly to prepare the cement concrete.

[0060] Comparative Example 4

[0061] The comparative example of the present application provides a cement concrete, which is prepared by the following steps: mixing 1150 kg of coarse aggregate, 600 kg of fine aggregate, 185 kg of cement, 75 kg of ultrafine limestone powder, 45 kg of fly ash, 30 kg of mineral powder and 80 kg of the loading agent prepared in Preparation Example 1, and then adding 5.5 kg of water reducer and 120 kg of water and stirring and mixing uniformly to prepare cement concrete.

[0062] Comparative Example 5

[0063] The comparative example of the present application provides a cement concrete, which is prepared by the following steps: mixing 1150 kg of coarse aggregate, 600 kg of fine aggregate, 185 kg of cement, 75 kg of ultrafine limestone powder, 45 kg of fly ash, 30 kg of mineral powder and 80 kg of the reinforcing agent prepared in Preparation Example 2, and then adding 5.5 kg of water reducer and 120 kg of water and stirring and mixing uniformly to prepare the cement concrete.

[0064] Comparative Example 6

[0065] The comparative example of the present application provides a cement concrete, which is prepared by the following steps: mixing 1150 kg of coarse aggregate, 600 kg of fine aggregate, 185 kg of cement, 75 kg of ultrafine limestone powder, 45 kg of fly ash and 30 kg of mineral powder, and then adding 5.5 kg of water reducer and 120 kg of water and stirring and mixing uniformly to prepare the cement concrete.

[0066] Table 1 Composition of Examples and Comparative Examples (kg)

[0067]

[0068]

[0069] Performance testing

[0070] The concrete prepared in the examples and comparative examples were subjected to 7d and 28d compressive strength tests with reference to GB50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". The size of the concrete test specimens was 150mm*150mm*150mm.

[0071] The concrete prepared in the examples and comparative examples was subjected to a 28-day chloride ion permeability coefficient test using the RCM method in accordance with GB / T50082-2009 "Test methods for long-term properties and durability of ordinary concrete." The concrete test specimens had a diameter of 100 mm and a height of 50 mm.

[0072] Table 2 Performance test data of examples and comparative examples

[0073]

[0074] From Example 2 and Comparative Examples 1, 4, 5, and 6, and from Table 2, it can be seen that the reinforcing agent is attached to the loading agent by the binder, and the reinforcing agent increases the bonding strength between the loading agent and other raw materials, while attracting chloride ions, causing the chloride ions to permeate inward from the stabilizer. During the permeation process, the chloride ions enter the loading agent through the reinforcing agent and the binder, thereby causing the chloride ions to be bound and absorbed, and unable to continue to permeate into the concrete, thereby effectively improving the chloride ion penetration resistance of the concrete.

[0075] Combining Example 2 with Comparative Example 2, Comparative Example 4, and Comparative Example 6 and Table 2, it can be seen that using red mud as a binder allows the ceramic powder and calcium hydroxide to be combined into a whole. The ceramic powder serves as the main supporting skeleton, and chloride ions are combined with calcium hydroxide and consumed, effectively reducing the chloride ions that penetrate into the concrete.

[0076] Combining Example 2 with Comparative Example 3, Comparative Example 5, and Comparative Example 6 and Table 2, it can be seen that triethanolamine is used to increase the compatibility of straw fiber and rubber powder, thereby allowing the straw fiber and rubber powder to combine, effectively increasing the capillary pores and air-entraining pores of the cement concrete, especially the capillary pores and air-entraining pores located near the stabilizer, and the pore structure becomes uniform. Chloride ions are combined with the loading agent from the capillary pores and air-entraining pores through the straw fiber and chitosan adhesive layer, thereby consuming the chloride ions.

[0077] From Example 2 and Comparative Examples 1-6 and Table 2, it can be seen that the straw fiber is modified with triethanolamine and rubber powder, and the ceramic powder, calcium hydroxide and red mud form a loading agent that acts as a load. Then, part of the lignin and cellulose are dissolved by sodium hydroxide solution, and the dissolved lignin and cellulose penetrate into the loading agent to strengthen the loading agent. At the same time, the chitosan solution has a bonding effect on the modified straw fiber, so that the modified straw fiber is bonded to the loading agent. The modified straw fiber increases the number of capillaries and air-entraining pores in the cement concrete portion close to the stabilizer. When chloride ions erode the concrete, the chloride ions reach the straw fibers through the capillaries and air-entraining pores. The straw fibers absorb the chloride ions and combine with the stabilizer. The chloride ions combined with the stabilizer are actually combined with the loading agent, thereby curbing the penetration of chloride ions and preventing the chloride ions from continuing to penetrate, thereby improving the chloride ion erosion resistance of the cement concrete.

[0078] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A limestone ultrafine powder cement concrete, characterized in that: The invention comprises the following raw materials in parts by weight: 1100-1200 parts of coarse aggregate, 550-650 parts of fine aggregate, 160-210 parts of cement, 4-7 parts of water reducer, 100-140 parts of water, 140-160 parts of admixture, wherein the admixture comprises ultrafine limestone powder, fly ash and mineral powder, and the weight ratio of the ultrafine limestone powder, fly ash and mineral powder is 5:3:2; and 60-120 parts of stabilizer, wherein the stabilizer comprises a load agent, a binder and a reinforcing agent, and the weight ratio of the load agent, the binder and the reinforcing agent is 3:1:

2. The supporting agent includes ceramic powder, calcium hydroxide and red mud, and the weight ratio of the ceramic powder, calcium hydroxide and red mud is 3:1:1; The binder comprises chitosan solution and sodium hydroxide solution, and the weight ratio of the chitosan solution to the sodium hydroxide solution is 4:1; The reinforcing agent comprises straw fiber, triethanolamine and rubber powder, and the weight ratio of the straw fiber, triethanolamine and rubber powder is 2:4:1; The loading agent is prepared by the following steps: mixing ceramic powder and calcium hydroxide, then adding red mud and performing disc granulation to form particles, and then drying the particles to obtain the loading agent; The reinforcing agent is prepared by the following steps: firstly, the straw fiber and triethanolamine are mixed and stirred evenly, then rubber powder is added and continued to be stirred and mixed, and then the reinforcing agent is dried after stirring for a period of time; The stabilizer is prepared by the following steps: firstly, mixing the enhancer with sodium hydroxide solution, then adding chitosan solution and mixing, and finally adding a loading agent and mixing evenly, and drying to prepare the stabilizer.

2. A method for preparing ultrafine limestone powder cement concrete according to claim 1, characterized in that: The following steps are involved: Coarse aggregate, fine aggregate, cement, admixture and stabilizer are mixed and stirred evenly, and then a water reducer and water are added and mixed and stirred evenly to prepare cement concrete.

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