Tobermorite series concrete early strength agent prepared by steam curing method and processing method of tobermorite series concrete early strength agent

Abstract

The invention relates to a tobermorite concrete early strength agent prepared by a steam curing method. The tobermorite concrete early strength agent comprises water, solid powder and an air entraining agent, the mass ratio of the water to the solid powder is 0.5-0.8; the solid powder comprises carbide slag, fly ash and cement. According to the invention, industrial solid wastes are used and molded under the cementing action of a small amount of cement, and a porous structure is formed under the action of an air entraining agent, so that steam can fully permeate, and all reactants fully react under the condition of steam curing to generate tobermorite crystals.

Description

Technical Field

[0001] The invention relates to a concrete early strength agent, and more specifically, to a tobermorite-based concrete early strength agent prepared by a steaming method and a processing method thereof. Background Art

[0002] Common types of concrete early strength agents mainly include the following: Inorganic salt early strength agent: Chloride: such as calcium chloride (CaCl2), which is one of the most commonly used early strength agents. The addition of calcium chloride can accelerate the hardening and setting process of cement and significantly improve the early strength of concrete. However, excessive use may cause steel corrosion, so the dosage needs to be strictly controlled.

[0003] Sulfate: such as sodium sulfate (Na2SO4), also known as glauber powder. It is often used in combination with other early strength agents to improve the early strength of concrete and accelerate cement hydration.

[0004] Organic early strength agent: Triethanolamine: It is a commonly used organic early strength agent. It can react with tricalcium aluminate in cement to form a complex, thereby accelerating the hydration and hardening process of cement. Triethanolamine is usually used in combination with other early strength agents to achieve better results.

[0005] Other organic compounds: including certain amines, alcohols, sugars, etc., which promote the hydration reaction of cement through different mechanisms and improve the early strength of concrete.

[0006] Composite early strength agent: Composite early strength agent is a compound of multiple early strength agent components in a certain proportion, aiming to comprehensively utilize the advantages of various early strength agents to achieve better early strength effect. Composite early strength agent usually includes a combination of inorganic salts and organic matter, as well as other possible additives such as retarders, water reducers, etc.

[0007] Special early strength agent: For example, calcium formate is particularly suitable for concrete construction in low temperature environments. Calcium formate can significantly lower the freezing point of concrete and promote the hydration reaction of cement at low temperatures, thereby accelerating the hardening and strength development of concrete.

[0008] Among these early strength agents, the application scope of chloride and sulfate early strength agents has been strictly limited due to their adverse effects on the durability of concrete. These early strength agents all have the problem of easily causing rapid shrinkage of concrete and reduced crack resistance.

[0009] Tobermorite is a calcium silicate mineral, usually belonging to the calcium silicate hydrate (CSH) class of minerals. This type of mineral is very important in geology and materials science, especially in cement, concrete and geological sediments. Tobermorite has a layered structure, composed of alternating molecular layers of calcium silicate and water, which gives it specific physical and chemical properties. In building materials, tobermorite is an important component of cement hydration products and has an important influence on the strength and durability of cement paste.

[0010] Tobermorite contains a large number of hydroxyl groups in its crystal structure, which promotes the hydration reaction of cement during cement hydration. Specifically, tobermorite can slowly release calcium hydroxide, which is an important product in cement hydration reaction, thereby accelerating the growth of cement strength. In addition, tobermorite can also form the skeleton structure of the cement gel system, providing stable support for the generation of hydration products and ensuring the stability and durability of cement gel. Therefore, tobermorite crystals can be used as a high-quality concrete early strength agent.

[0011] Because the microscopic particle structure of tobermorite can fill the gaps between cement particles, it increases the density and impermeability of cement. This filling effect helps to reduce micro cracks and pores in cement paste and improve the strength of cement paste. At the same time, because tobermorite can promote the hydration reaction and generate more hydration products, these hydration products can further fill the gaps in cement paste, so that the strength of cement paste is further improved. Therefore, tobermorite has a good promoting effect on both the early strength and the later strength of concrete.

[0012] Because Tobermorite can fill the gaps between cement particles, reducing the penetration channels of water and harmful substances, thereby reducing the permeability of concrete. At the same time, Tobermorite can also chemically react with some harmful substances, fixing them in the cement stone to prevent them from further corroding the concrete.

[0013] Compared with traditional early strength agents, tobermorite has better reinforcement effect on concrete, better crack resistance and shrinkage resistance, and has no adverse effect on the durability of concrete.

[0014] At present, the mainstream method for preparing tobermorite is the hydrothermal method. The use of supercritical hydrothermal method can further improve the efficiency of preparation. These methods require the powder to be evenly distributed in the liquid phase. Therefore, in the preparation process, it is also necessary to use ultrasound and other means to ensure that various raw materials are fully contacted and reacted in the liquid phase. Summary of the invention

[0015] In order to achieve the purpose of the present invention, the technical solution adopted by the present invention is: a tobermorite-based concrete early strength agent is prepared by a steaming method, comprising: water, solid powder and air entraining agent; the mass ratio between water and solid powder is: 0.5-0.8; the solid powder comprises: carbide slag, fly ash and cement.

[0016] Preferably, the mass ratio of various solid powders is: 25-35% carbide slag, 60-70% fly ash and 5-15% cement.

[0017] Preferably, the amount of air entraining agent is 0.5-0.8% of the powder.

[0018] Preferably, the air entraining agent includes: sodium dodecyl sulfate or triterpenoid saponin.

[0019] Preferably, the carbide slag needs to be dried and ball-milled to a specific surface area of ​​400-500m 2 / kg.

[0020] Preferably, a processing method for preparing a tobermorite-based concrete early strength agent by steam curing method comprises: After the solid powder is formed by adding water and air entraining agent, it is placed in a reactor for 24 hours and the reaction temperature is 120-130°C for 5-6 hours. After the reaction is completed, the test block is dried at 100-130°C for 2-5 hours, crushed and then put into a ball mill for grinding until the specific surface area is 450-500m2 / kg; When grinding, add diethylene glycol, triethanolamine and hydroxyethylethylenediamine in a mass ratio of 2:1:1, and the amount added is 0.1-0.5% of the amount of material fed into the mill; The ground powder is mixed with heavy calcium carbonate (particle size 0.5~1μm) prepared by wet method in a mixer at a mass ratio of 95:5.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses industrial solid waste, which is formed by the bonding action of a small amount of cement, and forms a porous structure under the action of an air entraining agent, which is convenient for steam to fully penetrate. Under the condition of steam curing, each reactant fully reacts to generate tobermorite crystals.

[0022] 2. Add diethylene glycol, triethanolamine and hydroxyethylethylenediamine to eliminate static electricity on the grinding body and improve the grinding effect.

[0023] 3. Mix the ground powder with the heavy calcium carbonate prepared by the wet method in a mixer to optimize the particle size distribution of the cementitious material and reduce the viscosity of the concrete mixture (especially for high-strength concrete with a large amount of cementitious material). In addition, the calcium ions in the heavy calcium carbonate can also induce the hydration of calcium silicate minerals in the early stage of cement hydration, and have a certain early strength effect. This further improves the early strength effect of the early strength agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The test block is a test block after the reaction of the tobermorite-based concrete early strength agent prepared by the steam curing method of the present invention is completed; Figure 2 This is a diagram showing the effect of the product after grinding of the tobermorite-based concrete early strength agent prepared by the steam curing method of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0026] Embodiment 1: Figure 1 to Figure 2 As shown in the figure, a processing method for preparing tobermorite concrete early strength agent by steam curing method is as follows: the calcium carbide slag is dried at 120°C for 3 hours, and then put into a ball mill to grind to a specific surface area of ​​425m 2 / kg, mixed with 30% carbide slag, 60% fly ash and 10% cement by mass ratio, and added with 0.6% sodium dodecyl sulfate powder; The mass ratio between water and solid powder is: add water at a ratio of 0.6 and stir the slurry thoroughly to form it.

[0027] A test block of 100×100×100 mm was prepared, and after standing for 24 hours, it was demoulded and placed in a reactor. The reaction temperature was 120° C. and the reaction time was 5 hours.

[0028] After the reaction, the test piece was dried at 120°C for 3 hours, crushed and ground to a specific surface area of ​​480 m 2 / kg, tobermorite concrete expansion agent is obtained.

[0029] During grinding, a mixture of three chemical substances, diethylene glycol, triethanolamine and hydroxyethylethylenediamine, is added in a mass ratio of 2:1:1, and the amount added is 0.1% of the amount of material entering the grinder; these chemical substances can eliminate static electricity on the grinding body and improve the grinding effect. More importantly, these surfactants can have a good fluidizing effect when used in concrete early strength agents, making the early strength agent more evenly distributed in the concrete mixture and achieving a better strengthening effect.

[0030] The ground powder and the wet-prepared heavy calcium carbonate (particle size 0.5μm) are mixed in a mixer at a mass ratio of 95:5. Ultrafine heavy calcium carbonate can better fill the pores of the cementitious material system, optimize the particle gradation of the cementitious material, and reduce the viscosity of the concrete mixture (especially for high-strength concrete with a large amount of cementitious material). In addition, the calcium ions in the heavy calcium carbonate can also induce the hydration of calcium silicate minerals in the early stage of cement hydration, and have a certain early strength effect. The early strength effect of the early strength agent is further improved.

[0031] When tobermorite-based expansive agent is added to cement at a dosage of 1%, the 1d strength of P.O42.5 cement increases from 11MPa to 19MPa, the 3d strength increases from 26MPa to 34MPa, and the 28d strength increases from 48MPa to 54MPa.

[0032] Compared with calcium formate, which has a relatively ideal application effect, with the same dosage of 1%, the 1d strength of P.O42.5 cement increases from 11MPa to 18MPa, the 3d strength increases from 26MPa to 32MPa, and the 28d strength increases from 48MPa to 49MPa.

[0033] Compared with the calcium formate early strength agent, under the same output, the increase in 1d strength and 3d strength of P.O42.5 cement by tobermorite-based expansive agent and calcium formate early strength agent is almost the same, and tobermorite is slightly higher than calcium formate. The 28d strength is significantly higher than calcium formate. The 28d strength of calcium formate early strength agent has almost no change compared with the benchmark, while the 28d strength of tobermorite-based early strength agent still has a significant increase.

[0034] Embodiment 2: The carbide slag was dried at 120℃ for 3 hours and then put into the ball mill to grind to a specific surface area of ​​400m 2 / kg, mixed with 35% carbide slag, 60% fly ash and 5% cement by mass ratio, and added with 0.5% triterpenoid saponin powder; The mass ratio of water to solid powder is 0.5: add water and stir the slurry thoroughly to form it.

[0035] The test block was prepared into 100×100×100mm and placed in a reactor after standing for 24 hours. The reaction temperature was 130℃ and the reaction time was 5.5 hours. After the reaction was completed, the test block was dried at 100℃ for 2 hours, crushed and ground to a specific surface area of ​​450m 2 / kg, tobermorite concrete expansion agent is obtained.

[0036] During grinding, a mixture of three chemical substances, diethylene glycol, triethanolamine and hydroxyethylethylenediamine, is added in a mass ratio of 2:1:1, and the amount added is 0.5% of the amount of material entering the grinder; these chemical substances can eliminate static electricity on the grinding body and improve the grinding effect. More importantly, these surfactants can have a good fluidizing effect when used in concrete early strength agents, making the early strength agent more evenly distributed in the concrete mixture and achieving a better strengthening effect.

[0037] The ground powder and the wet-prepared heavy calcium carbonate (particle size 0.8-1μm) are mixed in a mixer at a mass ratio of 95:5. Ultrafine heavy calcium carbonate can better fill the pores of the cementitious material system, optimize the particle gradation of the cementitious material, and reduce the viscosity of the concrete mixture (especially for high-strength concrete with a large amount of cementitious material). In addition, the calcium ions in the heavy calcium carbonate can also induce the hydration of calcium silicate minerals in the early stage of cement hydration, and have a certain early strength effect. The early strength effect of the early strength agent is further improved.

[0038] Embodiment 3: The carbide slag was dried at 130℃ for 2 hours and then put into the ball mill to grind to a specific surface area of ​​500m 2 / kg, mixed with 25% carbide slag, 60% fly ash and 15% cement by mass ratio, and added with 0.8% triterpenoid saponin powder; The mass ratio between water and solid powder is: add water at a ratio of 0.8 and stir the slurry thoroughly to form it.

[0039] The test block was prepared into 100×100×100mm and placed in a reactor after standing for 24 hours. The reaction temperature was 125℃ and the reaction time was 5.5 hours. After the reaction was completed, the test block was dried at 115℃ for 4 hours, crushed and ground to a specific surface area of ​​500m 2 / kg, tobermorite concrete expansion agent is obtained.

[0040] During grinding, a mixture of three chemical substances, diethylene glycol, triethanolamine and hydroxyethylethylenediamine, is added in a mass ratio of 2:1:1, and the amount added is 0.2% of the amount of material entering the grinder; these chemical substances can eliminate static electricity on the grinding body and improve the grinding effect. More importantly, these surfactants can have a good fluidizing effect when used in concrete early strength agents, making the early strength agent more evenly distributed in the concrete mixture and achieving a better strengthening effect.

[0041] The ground powder and the wet-prepared heavy calcium carbonate (particle size 0.6-0.8μm) are mixed in a mixer at a mass ratio of 95:5. Ultrafine heavy calcium carbonate can better fill the pores of the cementitious material system, optimize the particle gradation of the cementitious material, and reduce the viscosity of the concrete mixture (especially for high-strength concrete with a large amount of cementitious material). In addition, the calcium ions in the heavy calcium carbonate can also induce the hydration of calcium silicate minerals in the early stage of cement hydration, and have a certain early strength effect. The early strength effect of the early strength agent is further improved.

[0042] Embodiment 4: The carbide slag was dried at 125℃ for 3 hours and then put into the ball mill to grind to a specific surface area of ​​460m 2 / kg, mixed with 25% carbide slag, 70% fly ash and 5% cement by mass, and added with 0.7% sodium dodecyl sulfate powder; The mass ratio between water and solid powder is: add water at a ratio of 0.6 and stir the slurry thoroughly to form it.

[0043] The test blocks were prepared into 100×100×100 mm blocks, left to stand for 24 hours, demolded and placed in the reactor, with the reaction temperature at 120°C and the reaction time at 5 hours. After the reaction was completed, the test blocks were dried at 120°C for 3 hours, crushed and ground to a specific surface area of ​​460 m 2 / kg, tobermorite concrete expansion agent is obtained.

[0044] During grinding, a mixture of three chemical substances, diethylene glycol, triethanolamine and hydroxyethylethylenediamine, is added in a mass ratio of 2:1:1, and the amount added is 0.3% of the amount of material entering the grinder; these chemical substances can eliminate static electricity on the grinding body and improve the grinding effect. More importantly, these surfactants can have a good fluidizing effect when used in concrete early strength agents, making the early strength agent more evenly distributed in the concrete mixture and achieving a better strengthening effect.

[0045] The ground powder is mixed with heavy calcium carbonate (particle size 0.5-0.7 μm) prepared by wet method in a mixer at a mass ratio of 95:5.

[0046] The embodiments of the present invention disclose preferred embodiments, but are not limited thereto. A person skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not deviate from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. A tobermorite-based concrete early strength agent prepared by steam curing method, characterized in that: include: Water, solid powder and air entraining agent; The mass ratio between water and solid powder is: 0.5-0.8; The solid powder includes carbide slag, fly ash and cement.

2. The method for preparing a tobermorite-based concrete early strength agent according to claim 1, characterized in that: The mass ratio of various solid powders is: carbide slag 25-35%, fly ash 60-70% and cement 5-15%.

3. The method for preparing a tobermorite-based concrete early strength agent according to claim 1, characterized in that: The dosage of air entraining agent is 0.5-0.8% of the powder.

4. The method for preparing a tobermorite-based concrete early strength agent according to claim 1, characterized in that: The air entraining agent includes sodium dodecyl sulfate or triterpenoid saponin.

5. The method for preparing a tobermorite-based concrete early strength agent according to claim 1, characterized in that: The carbide slag needs to be dried and ball-milled, and the specific surface area after the treatment is 400-500m2 / kg.

6. A processing method for preparing a tobermorite-based concrete early strength agent by a steam curing method according to any one of claims 1 to 5, characterized in that: include: After the solid powder is formed by adding water and air entraining agent, it is placed in a reactor for 24 hours and the reaction temperature is 120-130°C for 5-6 hours. After the reaction is completed, the test block is dried at 100-130°C for 2-5 hours, crushed and then put into a ball mill for grinding until the specific surface area is 450-500m2 / kg; When grinding, add diethylene glycol, triethanolamine and hydroxyethylethylenediamine in a mass ratio of 2:1:1, and the amount added is 0.1-0.5% of the amount of material fed into the mill; The ground powder is mixed with heavy calcium carbonate (particle size 0.5~1μm) prepared by wet method in a mixer at a mass ratio of 95:5.

Images