Anti-freezing sea sand UHPC admixture prepared based on seawater and preparation method of anti-freezing sea sand UHPC admixture

Abstract

The invention discloses an anti-freezing sea sand UHPC additive prepared on the basis of seawater and a preparation method of the anti-freezing sea sand UHPC additive, and the additive comprises polycarboxylic acid powder, a defoaming agent, concentrated pretreated seawater, triethanolamine, urea, sodium chloride and a 30% sodium hydroxide solution. The freezing damage resistance of the sea sand UHPC can be enhanced, the plasticizing function is improved, and the soil durability is improved. In the preparation process, the seawater is pretreated, and the concentrated and pretreated seawater is further processed and each component is added during compounding, so that a material B with special characteristics is generated; the material A is added on the basis of the material B, that is, the UHPC special material is adjusted in real time in use in a two-mixing mode so as to meet the working performance requirement. By adopting the preparation method disclosed by the invention, the effects of improving the traditional technology and simultaneously realizing the resource utilization of the seawater sand can be achieved, and meanwhile, the effect of no subsequent environmental protection problem is achieved.

Description

Technical Field

[0001] The present invention relates to the field of building materials, and more specifically, to an antifreeze sea sand UHPC admixture prepared based on seawater and a preparation method thereof. Background Art

[0002] In recent years, UHPC and its components have been vigorously developed due to their excellent mechanical properties, durability, applicability and economy. They are one of the important fixed materials for construction in high-performance component systems. UHPC, the full name of which is Ultra-High Performance Concrete, is a high-performance material composed of high-performance cementitious materials, early strength aggregates, functional admixtures and additives. It can be widely used in various structural parts and construction scenarios. Winter construction of concrete is inevitable. my country stipulates that winter construction begins when the average daily outdoor temperature is below 5°C. In order to ensure the quality and progress of concrete construction, winter concrete admixtures - antifreeze are generally used. Antifreeze is a kind of concrete admixture that can harden concrete at negative temperatures without heating, and ultimately achieve the same quality level as concrete maintained at room temperature.

[0003] As the technology of preparing UHPC with sea sand as raw material becomes more and more mature, the preparation of sea sand UHPC usually takes materials nearby, and sea sand is used as raw material for the production of building components. For the production of sea sand UHPC near the ocean environment, there is a shortage of fresh water resources. At present, the annual water consumption of construction is extremely high. Groundwater and river water are the main sources of natural water for construction, but the supply of groundwater and river water is limited by resources and environmental conditions, and is far from meeting the national demand for construction water. Desalination of seawater has become an important part of construction water. However, seawater desalination is not only costly, but also causes environmental problems. Some marine organisms such as small fish and plankton will disrupt the food chain in the ocean after being eliminated. In addition, how to deal with the high-purity salt produced by seawater desalination is also an important issue. If these high-salt wastewaters are discharged into the sea, local aquatic crops will be seriously damaged. If the seawater is used directly without desalination, it will cause rust on steel fibers and other metal objects, which will easily cause quality problems and reduced durability, and increase subsequent maintenance costs. In addition, due to the complex production and use environment of sea sand UHPC, various admixtures are often required, especially under winter construction conditions, antifreeze needs to be added to improve the working performance of sea sand UHPC.

[0004] After analyzing the composition of seawater, it can be found that the main components of seawater include cations Na+, K+, Ca2+, Mg2+ and Sr2+, anions C1-, S042-, Br-, HCO3-, CO32- and F-, and H3BO3 in molecular form, which together account for 99.9% of the salt content of seawater. How to efficiently utilize the effective components in seawater, reduce the damage to the environment during the use of seawater, and at the same time, be able to construct high-performance sea sand UHPC in winter has become an important technical problem that technicians in this field need to solve urgently. Summary of the invention

[0005] The invention discloses an antifreeze sea sand UHPC admixture based on seawater. The admixture comprises the following components: polycarboxylic acid powder, a defoamer, concentrated pretreated seawater, triethanolamine, urea, sodium chloride and a 30% sodium hydroxide solution.

[0006] Preferably, the components of the admixture are calculated by weight as follows: 2 to 13 parts by weight of polycarboxylic acid powder, 0.05 to 0.22 parts by weight of defoaming agent, 78 to 89 parts by weight of concentrated pretreated seawater, 2 to 10 parts by weight of triethanolamine, 1 to 3 parts by weight of urea, 1 to 3 parts by weight of sodium chloride, and 3 to 8 parts by weight of 30% sodium hydroxide solution.

[0007] Preferably, the concentrated pretreated seawater is pretreated by boiling.

[0008] A method for preparing an antifreeze sea sand UHPC admixture based on seawater comprises the following steps:

[0009] Step S1: taking seawater, boiling it at high temperature for 5 to 20 minutes, filtering it to remove impurities, gases and volatile substances, and obtaining concentrated pretreated seawater;

[0010] Step S2: taking polycarboxylic acid powder and defoaming agent and mixing them to obtain material A;

[0011] Step S3: injecting concentrated pretreated seawater into the reactor to heat it up, and then maintaining a constant temperature after heating;

[0012] Step S4: Weigh urea and dissolve it in a reaction kettle, mix and stir evenly, and keep stirring at a fixed speed;

[0013] Step S5: After the urea is fully dissolved, continue stirring until the next step begins;

[0014] Step S6: heating to 100° C., weighing sodium chloride and dissolving it in the reaction kettle, maintaining a fixed rotation speed, and stirring continuously after the sodium chloride is fully dissolved. After the stirring is completed, the mixture is kept warm for reaction to prepare a composite liquid;

[0015] Step S7: After the temperature of the composite liquid in the reaction kettle is lowered, the catalyst and triethanolamine are added, stirred evenly, and then the stirring is continued for 15 to 30 minutes, and then the stirring speed is increased, 30% sodium hydroxide solution is added, and the pH value is adjusted to 9 to 10 to obtain a mixed solution;

[0016] Step S8: filtering the mixed solution obtained in the previous step through a 100-mesh sieve to obtain material B;

[0017] Step S9: In the preparation process of sea sand UHPC, material B is added first, and then material A is added on the basis of material B.

[0018] Preferably, in step S3, the concentrated pretreated seawater is heated to 80°C within 1 hour and maintained at a constant temperature.

[0019] Preferably, in step S4, the fixed speed of stirring after the addition of anhydrous sodium sulfate is determined according to the diameter of the reactor;

[0020] When the diameter of the reactor is less than 0.8 meters, the fixed speed is 300r / min;

[0021] When the diameter of the reactor is 0.8 to 1.5 meters, the fixed speed is 400 to 450 r / min;

[0022] When the diameter of the reactor is 1.5-2 meters, the fixed rotation speed is 600-650 r / min.

[0023] Preferably, in step S5, specifically: after the urea is fully dissolved, stirring is continued at a speed of 270 to 330 r / min for 10 to 20 min until the next step starts.

[0024] Preferably, in step S6, the fixed rotation speed maintained when sodium chloride is dissolved in the reactor is determined according to the diameter of the reactor;

[0025] When the diameter of the reactor is less than 0.8 meters, the fixed speed is 300r / min;

[0026] When the diameter of the reactor is 0.8 to 1.5 meters, the fixed speed is 400 to 450 r / min;

[0027] When the diameter of the reactor is 1.5 to 2 meters, the fixed speed is 600 to 650 r / min;

[0028] After the sodium chloride is fully dissolved, the stirring time is continued for 10 to 20 minutes, and the heat preservation reaction time after the stirring is completed is 24 to 48 hours.

[0029] Preferably, in step S7, specifically: wait for the composite liquid in the reaction kettle to cool to 20-30° C., add the catalyst and triethanolamine at a speed of 180-220 r / min, stir evenly, and continue stirring for 15-30 min, increase the speed to 360-440 r / min, and then add 30% sodium hydroxide solution after speeding up.

[0030] Preferably, in step S7, specifically:

[0031] A fixed amount of 30% sodium hydroxide solution is added to the composite liquid each time, and after each addition, the mixture needs to be stirred at a speed of 360-440 r / min for at least 5 minutes;

[0032] Use a glass rod to dip a drop of suspension onto a pH test paper, and then compare the color change of the test paper with the standard colorimetric card to determine the pH value of the test solution.

[0033] If the set pH value is not reached, a fixed amount of sodium hydroxide solution is added and the above operation is repeated;

[0034] If the set pH value of 9 to 10 is reached, stop adding the 30% sodium hydroxide solution, continue stirring for 30 to 60 minutes, and check the pH value again until the pH value is 9 to 10, then stop stirring.

[0035] The present invention provides an antifreeze sea sand UHPC admixture based on seawater, the admixture includes polycarboxylic acid powder, defoamer, concentrated pretreated seawater, triethanolamine, urea, sodium chloride and 30% sodium hydroxide solution. By adding the admixture to the sea sand UHPC, the antifreeze damage ability of the sea sand UHPC can be enhanced, the plasticization function can be improved, and the soil durability can be improved. In the preparation process, the present invention adopts the method of pre-treating the seawater, further processing and adding various components to the concentrated pre-treated seawater during compounding to generate a B material with proprietary characteristics; adding A material to the B material, that is, through the two-mixing method, the UHPC special material is adjusted in real time when it is used to meet the working performance requirements. By adopting the preparation method of the present invention, it is possible to achieve the effect of improving traditional technology and realizing the resource utilization of seawater sand at the same time, and at the same time achieve the effect of no subsequent environmental protection problems. DETAILED DESCRIPTION

[0036] The present invention discloses a UHPC admixture for preparing antifreeze sea sand based on seawater and a preparation method thereof, wherein the seawater is pretreated, and the concentrated pretreated seawater is further processed and various components are added during compounding to generate a B material with proprietary characteristics; the A material is added to the B material, that is, through a two-mixing method, the UHPC special material is adjusted in real time during use to meet the working performance requirements. By adopting the preparation method of the present invention, the effects of improving traditional technology and realizing the resource utilization of seawater sand can be achieved at the same time.

[0037] The technical solutions in the embodiments of the present invention are described clearly and in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0038] The invention provides an antifreeze sea sand UHPC admixture based on seawater. The admixture comprises the following components: polycarboxylic acid powder, a defoamer, concentrated pretreated seawater, triethanolamine, urea, sodium chloride and a 30% sodium hydroxide solution.

[0039] The cost of desalination treatment is high and the purification effect is difficult to achieve the best. If the seawater is directly applied to UHPC without treatment, there will be problems such as high risk of cracking and metal corrosion caused by high cement, water reducing agent and water consumption. In an embodiment of the present invention, the concentrated pre-treated seawater is to treat ordinary seawater in a simple and easy-to-implement manner such as heating and boiling to remove unstable organic matter, gas components and volatile substances, and the concentration of seawater is controlled. The main components of seawater are cations Na+, K+, Ca2+, Mg2+ and Sr2+, anions Cl-, S042-, Br-, HCO3-, CO32-, F-, etc., and H3BO3 in molecular form, which together account for 99.9% of the salinity of seawater. In order to reduce the risks of direct use of seawater, this embodiment combines the treated concentrated pretreated seawater with polycarboxylic acid powder, defoaming agent, triethanolamine, urea, sodium chloride and 30% sodium hydroxide solution. By compounding these components with the concentrated pretreated seawater to generate an additive with antifreeze properties, the main components in the seawater are effectively utilized, greatly reducing the waste discharged into the natural environment.

[0040] Preferably, the components of the admixture are calculated by weight as follows: 2 to 13 parts by weight of polycarboxylic acid powder, 0.05 to 0.22 parts by weight of defoaming agent, 78 to 89 parts by weight of concentrated pretreated seawater, 2 to 10 parts by weight of triethanolamine, 1 to 3 parts by weight of urea, 1 to 3 parts by weight of sodium chloride, and 3 to 8 parts by weight of 30% sodium hydroxide solution.

[0041] Winter construction of concrete is inevitable. my country stipulates that winter construction begins when the average daily outdoor temperature is below 5°C. In order to ensure the quality and progress of concrete construction, winter concrete admixtures - antifreeze are generally used. Antifreeze is a kind of concrete that can harden at negative temperatures without heating, and eventually reach the same quality level as concrete maintained at room temperature. The main function of antifreeze in concrete is to improve early strength and prevent concrete from being damaged by freezing. One of the effective components in antifreeze is a substance that lowers the freezing point. Its main function is to freeze the water in the concrete at the lowest possible temperature to prevent frost heave stress caused by freezing of water. At the same time, a part of the water that does not freeze is maintained to maintain the hydration reaction and ensure the increase of concrete strength at negative temperatures. Most antifreezes are composite admixtures, consisting of antifreeze components, early strength components, water-reducing components, air-entraining components, carriers and other materials.

[0042] According to the weight proportions of polycarboxylic acid powder, defoamer, triethanolamine, urea, sodium chloride and 30% sodium hydroxide solution provided in this embodiment, a mixture with improved UHPC functionality is prepared with concentrated pretreated seawater. The mixture is added to the premix of sea sand UHPC. At -13±3°C, the strength of the sea sand UHPC aged 7 days reaches 40% of the 28-day strength of the standard-cured test block, and the 28-day strength reaches 70%. The strength reaches the designed strength grade after 28 days of negative temperature curing and 28 days of standard curing. The admixture of the present invention has a certain plasticizing effect and can improve the workability of concrete. When the water reduction rate is controlled at about 15%, the slump of concrete can be increased from 5cm to 12cm. In addition, the admixture of the present invention has small shrinkage and no corrosion damage to steel bars.

[0043] Preferably, the concentrated pretreated seawater is boiled to remove unstable organic matter, gas components and volatile substances from the seawater, and the concentration of the seawater is further increased after boiling.

[0044] A method for preparing an antifreeze sea sand UHPC admixture based on seawater comprises the following steps:

[0045] Step S1: taking seawater, boiling it at high temperature for 5 to 20 minutes, filtering it to remove impurities, gases and volatile substances, and obtaining concentrated pretreated seawater;

[0046] Step S2: taking polycarboxylic acid powder and defoaming agent and mixing them to obtain material A;

[0047] Step S3: injecting concentrated pretreated seawater into the reactor to heat it up, and then maintaining a constant temperature after heating;

[0048] Step S4: Weigh urea and dissolve it in a reaction kettle, mix and stir evenly, and keep stirring at a fixed speed;

[0049] Step S5: After the urea is fully dissolved, continue stirring until the next step begins;

[0050] Step S6: heating to 100° C., weighing sodium chloride and dissolving it in the reaction kettle, maintaining a fixed rotation speed, and stirring continuously after the sodium chloride is fully dissolved. After the stirring is completed, the mixture is kept warm for reaction to prepare a composite liquid;

[0051] Step S7: After the temperature of the composite liquid in the reaction kettle is lowered, the catalyst and triethanolamine are added, stirred evenly, and then the stirring is continued for 15 to 30 minutes, and then the stirring speed is increased, 30% sodium hydroxide solution is added, and the pH value is adjusted to 9 to 10 to obtain a mixed solution;

[0052] Step S8: filtering the mixed solution obtained in the previous step through a 100-mesh sieve to obtain material B;

[0053] Step S9: In the preparation process of sea sand UHPC, material B is added first, and then material A is added on the basis of material B.

[0054] This preparation process treats seawater from two directions:

[0055] First, pre-treat the seawater; after boiling, remove unstable organic matter, gas components and volatile substances. The main components in seawater mainly refer to the components with a concentration greater than 1mg / lkg in seawater. There are five cations Na+, K+, Ca2+, Mg2+ and Sr2+, six anions C1-, S042-, Br-, HCO3-, CO32-, F-, and H3BO3 in molecular form, which together account for 99.9% of the salt content of seawater. So it is called the main component. Other substances are added to the main components to compound them into various functional admixtures (early strength type, slow setting type, accelerating setting type, rapid setting type, flocculation type, waterproof type, expansion type, antifreeze type, thickening type, etc.).

[0056] Secondly, the adaptability of seawater admixtures and special materials is treated; triethanolamine, urea, sodium chloride and 30% sodium hydroxide solution are added to the concentrated and treated seawater after pretreatment, and added in steps to treat it, generating material B with rapid setting and early strength characteristics, so that it has the effect of improving early strength and accelerating solidification. Then, different proportions of material A are added to material B, that is, through the two-mixing method, the UHPC special material is adjusted in real time during use to meet the working performance requirements. The two materials are combined to first prepare material B that meets the durability and mechanical properties, and the working performance is controlled by adjusting the proportion of material A, so that UHPC with various characteristics of excellent performance can be prepared. It is often only necessary to adjust the components with greater influence in material B to configure different types of UHPC or UHPC premix admixtures.

[0057] When adjusting adaptability in the traditional mode, no distinction is made between A and B materials. Each adjustment is made by adjusting different proportions of all components to test different types of UHPC or UHPC premix admixtures. The components with large and small impacts in the admixtures are not distinguished. A joint adjustment method is adopted, resulting in long R&D time, time-consuming test batching, many quality control links, low production efficiency and high costs.

[0058] The preparation method has the following advantages:

[0059] High utilization rate of seawater; compared with the general seawater desalination process, the marine life will be destroyed after the seawater enters the desalination plant, causing the food chain in the ocean to be disordered, and the high-purity salt produced by seawater desalination will cause serious damage to local aquatic crops. This preparation method can realize the resource utilization of seawater while using seawater to make antifreeze sea sand UHPC admixture to achieve the effect of no subsequent environmental protection problems.

[0060] The performance of sea sand UHPC is improved; the admixture prepared by the preparation method is added to the sea sand UHPC premix, the amount of material B is 2% to 4% of the mass of the cementitious material in the sea sand UHPC, the water reduction rate is 10% to 15%, and the strength of the concrete aged for 7 days under -13±3℃ reaches 40% of the strength of 28 days of standard curing, and the strength of 28 days reaches 70%. The strength of 28 days of standard curing at negative temperature reaches the design strength grade. It has a certain plasticizing effect and can improve the workability of concrete. When the water reduction rate is controlled at about 15%, the slump of concrete can be increased from 5cm to 12cm. It has small shrinkage and no corrosion damage to steel bars.

[0061] The admixture prepared by this method is a light yellow transparent liquid with a pH value of 9-10 and a relative density of 1.17-1.20. It is easy to store and can be stored for two years without deterioration by simply sealing and packing in barrels. When the admixture prepared by this method is used, material B can be added to the stirring water first, or it can be added when the sea sand UHPC is stirred, and then an appropriate amount of material A can be added to adjust to meet the construction requirements.

[0062] Preferably, in step S3, the concentrated pretreated seawater is heated to 80°C within 1 hour and maintained at a constant temperature.

[0063] Preferably, in step S4, the fixed speed of stirring after the addition of anhydrous sodium sulfate is determined according to the diameter of the reactor;

[0064] When the diameter of the reactor is less than 0.8 meters, the fixed speed is 300r / min;

[0065] When the diameter of the reactor is 0.8 to 1.5 meters, the fixed speed is 400 to 450 r / min;

[0066] When the diameter of the reactor is 1.5-2 meters, the fixed rotation speed is 600-650 r / min.

[0067] Preferably, in step S5, specifically: after the urea is fully dissolved, stirring is continued at a speed of 270 to 330 r / min for 10 to 20 min until the next step starts.

[0068] Preferably, in step S6, the fixed rotation speed maintained when sodium chloride is dissolved in the reactor is determined according to the diameter of the reactor;

[0069] When the diameter of the reactor is less than 0.8 meters, the fixed speed is 300r / min;

[0070] When the diameter of the reactor is 0.8 to 1.5 meters, the fixed speed is 400 to 450 r / min;

[0071] When the diameter of the reactor is 1.5 to 2 meters, the fixed speed is 600 to 650 r / min;

[0072] After the sodium chloride is fully dissolved, the stirring time is continued for 10 to 20 minutes, and the heat preservation reaction time after the stirring is completed is 24 to 48 hours.

[0073] Preferably, in step S7, specifically: wait for the composite liquid in the reaction kettle to cool to 20-30° C., add the catalyst and triethanolamine at a speed of 180-220 r / min, stir evenly, and continue stirring for 15-30 min, increase the speed to 360-440 r / min, and then add 30% sodium hydroxide solution after speeding up.

[0074] Preferably, in step S7, specifically:

[0075] A fixed amount of 30% sodium hydroxide solution is added to the composite liquid each time, and after each addition, the mixture needs to be stirred at a speed of 360-440 r / min for at least 5 minutes;

[0076] Use a glass rod to dip a drop of suspension onto a pH test paper, and then compare the color change of the test paper with the standard colorimetric card to determine the pH value of the test solution.

[0077] If the set pH value is not reached, a fixed amount of sodium hydroxide solution is added and the above operation is repeated;

[0078] If the set pH value of 9 to 10 is reached, stop adding the 30% sodium hydroxide solution, continue stirring for 30 to 60 minutes, and check the pH value again until the pH value is 9 to 10, then stop stirring.

[0079] The following is described through multiple embodiments:

[0080] Embodiment 1:

[0081] Step S1: taking seawater, boiling it at high temperature for 5 to 20 minutes, filtering it to remove impurities, gases and volatile substances, and obtaining concentrated pretreated seawater;

[0082] Step S2: 2 to 13 parts by weight of polycarboxylic acid powder and 0.05 to 0.22 parts by weight of a defoaming agent are mixed and stirred to obtain material A;

[0083] Step S3: injecting 78 to 89 parts by weight of concentrated pretreated seawater into a reaction kettle and heating the temperature to 80° C. within 1 hour, and maintaining a constant temperature after heating;

[0084] Step S4: Weigh urea and dissolve it in a reaction kettle, mix and stir evenly, and keep stirring at a fixed speed;

[0085] Step S5: After 1 to 3 parts by weight of urea are fully dissolved, stirring is continued at a speed of 270 to 330 r / min for 10 to 20 min until the next step begins;

[0086] Step S6: heating to 100° C., weighing 1 to 3 parts by weight of sodium chloride and dissolving it in a reaction kettle, maintaining a fixed rotation speed, and stirring continuously for 10 to 20 minutes after the sodium chloride is fully dissolved. After the stirring is completed, heat-retaining the reaction for 24 to 48 hours to prepare a composite liquid;

[0087] Step S7: After the temperature of the composite liquid in the reaction kettle is lowered to 20-30° C., a catalyst and 2-10 parts by weight of triethanolamine are added at a speed of 180-220 r / min, and stirred evenly, and then stirring is continued for 15-30 minutes, and then the stirring speed is increased to 360-440 r / min, 3-8 parts by weight of 30% sodium hydroxide solution are added, and the pH value is adjusted to 9-10 to obtain a mixed solution;

[0088] Step S8: filtering the mixed solution obtained in the previous step through a 100-mesh sieve to obtain material B;

[0089] Step S9: In the preparation process of sea sand UHPC, material B is added first, and then material A is added on the basis of material B.

[0090] Embodiment 2:

[0091] Step S1: taking seawater, boiling it at high temperature for 5 minutes, filtering it to remove impurities, gases and volatile substances, and obtaining concentrated pretreated seawater;

[0092] Step S2: 2 parts by weight of polycarboxylic acid powder and 0.05 parts by weight of defoaming agent are mixed and stirred to obtain material A;

[0093] Step S3: inject 78 parts by weight of concentrated pretreated seawater into the reactor and heat it to 80° C. within 1 hour, and then maintain a constant temperature;

[0094] Step S4: Weigh urea and dissolve it in a reaction kettle, mix and stir evenly, and keep stirring at a fixed speed;

[0095] Step S5: After 1 to 3 parts by weight of urea are fully dissolved, stirring is continued at a speed of 270 r / min for 10 min until the next step begins;

[0096] Step S6: heating to 100° C., weighing 1 to 3 parts by weight of sodium chloride and dissolving it in a reaction kettle, maintaining a fixed rotation speed, stirring continuously for 10 minutes after the sodium chloride is fully dissolved, and then keeping the temperature for reaction for 24 hours after the stirring is completed to prepare a composite liquid;

[0097] Step S7: After the temperature of the composite liquid in the reaction kettle is reduced to 20° C., the catalyst and 2 parts by weight of triethanolamine are added at a speed of 180 r / min, stirred evenly, and then stirred for 15 minutes, and then the stirring speed is increased to 360 r / min, 3 parts by weight of 30% sodium hydroxide solution are added, and the pH value is adjusted to 9 to obtain a mixed solution;

[0098] Step S8: filtering the mixed solution obtained in the previous step through a 100-mesh sieve to obtain material B;

[0099] Step S9: In the preparation process of sea sand UHPC, material B is added first, and then material A is added on the basis of material B.

[0100] Embodiment 3:

[0101] Step S1: taking seawater, boiling it at high temperature for 12.5 minutes, filtering it to remove impurities, gases and volatile substances, and obtaining concentrated pretreated seawater;

[0102] Step S2: 7.5 parts by weight of polycarboxylic acid powder and 0.135 parts by weight of defoaming agent are mixed and stirred to obtain material A;

[0103] Step S3: inject 83.5 parts by weight of concentrated pretreated seawater into the reactor and heat it to 80° C. within 1 hour, and then maintain a constant temperature;

[0104] Step S4: Weigh urea and dissolve it in a reaction kettle, mix and stir evenly, and keep stirring at a fixed speed;

[0105] Step S5: After 2 parts by weight of urea are fully dissolved, stirring is continued at a speed of 300 r / min for 15 min until the next step begins;

[0106] Step S6: heating to 100° C., weighing 2 parts by weight of sodium chloride and dissolving it in the reaction kettle, maintaining a fixed rotation speed, stirring continuously for 15 minutes after the sodium chloride is fully dissolved, and then keeping the temperature for reaction for 36 hours to prepare a composite liquid;

[0107] Step S7: After the temperature of the composite liquid in the reaction kettle is reduced to 25° C., the catalyst and 6 parts by weight of triethanolamine are added at a speed of 200 r / min, stirred evenly, and then stirred for 22.5 min, and then the stirring speed is increased to 400 r / min, 5.5 parts by weight of 30% sodium hydroxide solution are added, and the pH value is adjusted to 9.5 to obtain a mixed solution;

[0108] Step S8: filtering the mixed solution obtained in the previous step through a 100-mesh sieve to obtain material B;

[0109] Step S9: In the preparation process of sea sand UHPC, material B is added first, and then material A is added on the basis of material B.

[0110] Embodiment 4:

[0111] Step S1: taking seawater, boiling it at high temperature for 20 minutes, filtering it to remove impurities, gases and volatile substances, and obtaining concentrated pretreated seawater;

[0112] Step S2: 13 parts by weight of polycarboxylic acid powder and 0.22 parts by weight of defoaming agent are mixed and stirred to obtain material A;

[0113] Step S3: injecting 89 parts by weight of concentrated pretreated seawater into the reactor and heating the temperature to 80° C. within 1 hour, and maintaining a constant temperature after heating;

[0114] Step S4: Weigh urea and dissolve it in a reaction kettle, mix and stir evenly, and keep stirring at a fixed speed;

[0115] Step S5: After 3 parts by weight of urea are fully dissolved, stirring is continued at a speed of 330 r / min for 20 min until the next step begins;

[0116] Step S6: heating to 100° C., weighing 3 parts by weight of sodium chloride and dissolving it in the reaction kettle, maintaining a fixed rotation speed, stirring continuously for 20 minutes after the sodium chloride is fully dissolved, and then keeping the temperature for reaction for 48 hours after the stirring is completed to prepare a composite liquid;

[0117] Step S7: After the temperature of the composite liquid in the reaction kettle is reduced to 30° C., the catalyst and 10 parts by weight of triethanolamine are added at a speed of 220 r / min, stirred evenly, and then stirred for 30 minutes, and then the stirring speed is increased to 440 r / min, 8 parts by weight of 30% sodium hydroxide solution are added, and the pH value is adjusted to 10 to obtain a mixed solution;

[0118] Step S8: filtering the mixed solution obtained in the previous step through a 100-mesh sieve to obtain material B;

[0119] Step S9: In the preparation process of sea sand UHPC, material B is added first, and then material A is added on the basis of material B.

[0120] The present invention provides an antifreeze sea sand UHPC admixture based on seawater, the admixture includes polycarboxylic acid powder, defoamer, concentrated pretreated seawater, triethanolamine, urea, sodium chloride and 30% sodium hydroxide solution. By adding the admixture to the sea sand UHPC, the antifreeze damage ability of the sea sand UHPC can be enhanced, the plasticization function can be improved, and the soil durability can be improved. In the preparation process, the present invention adopts the method of pre-treating the seawater, further processing and adding various components to the concentrated pre-treated seawater during compounding to generate a B material with proprietary characteristics; adding A material to the B material, that is, through the two-mixing method, the UHPC special material is adjusted in real time when it is used to meet the working performance requirements. By adopting the preparation method of the present invention, it is possible to achieve the effect of improving traditional technology and realizing the resource utilization of seawater sand at the same time, and at the same time achieve the effect of no subsequent environmental protection problems.

[0121] The above is a detailed introduction to the preparation of the antifreeze sea sand UHPC admixture based on seawater and the preparation method thereof provided by the present invention. For those skilled in the art, according to the ideas of the embodiments of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing an antifreeze sea sand UHPC admixture based on seawater, characterized in that: The additive comprises the following components: polycarboxylic acid powder, defoamer, concentrated pretreated seawater, triethanolamine, urea, sodium chloride and 30% sodium hydroxide solution.

2. The method for preparing an antifreeze sea sand UHPC admixture based on seawater according to claim 1, characterized in that: The components of the admixture are calculated by weight as follows: 2 to 13 parts by weight of polycarboxylic acid powder, 0.05 to 0.22 parts by weight of defoaming agent, 78 to 89 parts by weight of concentrated pretreated seawater, 2 to 10 parts by weight of triethanolamine, 1 to 3 parts by weight of urea, 1 to 3 parts by weight of sodium chloride, and 3 to 8 parts by weight of 30% sodium hydroxide solution.

3. The method for preparing an antifreeze sea sand UHPC admixture based on seawater according to claim 1, characterized in that: The concentrated pretreated seawater is pretreated by boiling.

4. The method for preparing an antifreeze sea sand UHPC admixture based on seawater according to any one of claims 1 to 3, characterized in that: The following steps are included: Step S1: taking seawater, boiling it at high temperature for 5 to 20 minutes, filtering it to remove impurities, gases and volatile substances, and obtaining concentrated pretreated seawater; Step S2: taking polycarboxylic acid powder and defoaming agent and mixing them to obtain material A; Step S3: injecting concentrated pretreated seawater into the reactor to heat it up, and then maintaining a constant temperature after heating; Step S4: Weigh urea and dissolve it in a reaction kettle, mix and stir evenly, and keep stirring at a fixed speed; Step S5: After the urea is fully dissolved, continue stirring until the next step begins; Step S6: heating to 100° C., weighing sodium chloride and dissolving it in the reaction kettle, maintaining a fixed rotation speed, and stirring continuously after the sodium chloride is fully dissolved. After the stirring is completed, the mixture is kept warm for reaction to prepare a composite liquid; Step S7: After the temperature of the composite liquid in the reaction kettle is lowered, the catalyst and triethanolamine are added, stirred evenly, and then the stirring is continued for 15 to 30 minutes, and then the stirring speed is increased, 30% sodium hydroxide solution is added, and the pH value is adjusted to 9 to 10 to obtain a mixed solution; Step S8: filtering the mixed solution obtained in the previous step through a 100-mesh sieve to obtain material B; Step S9: In the preparation process of sea sand UHPC, material B is added first, and then material A is added on the basis of material B.

5. The method for preparing antifreeze sea sand UHPC admixture based on seawater according to claim 4, characterized in that: In step S3, the concentrated pretreated seawater is heated to 80°C within 1 hour and maintained at a constant temperature.

6. The method for preparing antifreeze sea sand UHPC admixture based on seawater according to claim 4, characterized in that: In step S4, the fixed stirring speed after the addition of anhydrous sodium sulfate is determined according to the diameter of the reactor; When the diameter of the reactor is less than 0.8 meters, the fixed speed is 300r / min; When the diameter of the reactor is 0.8 to 1.5 meters, the fixed speed is 400 to 450 r / min; When the diameter of the reactor is 1.5-2 meters, the fixed rotation speed is 600-650 r / min.

7. The method for preparing antifreeze sea sand UHPC admixture based on seawater according to claim 4, characterized in that: In step S5, specifically, after the urea is fully dissolved, stirring is continued at a speed of 270 to 330 r / min for 10 to 20 minutes until the next step begins.

8. The method for preparing antifreeze sea sand UHPC admixture based on seawater according to claim 4, characterized in that: In step S6, the fixed rotation speed maintained when sodium chloride is dissolved in the reactor is determined according to the diameter of the reactor; When the diameter of the reactor is less than 0.8 meters, the fixed speed is 300r / min; When the diameter of the reactor is 0.8 to 1.5 meters, the fixed speed is 400 to 450 r / min; When the diameter of the reactor is 1.5 to 2 meters, the fixed speed is 600 to 650 r / min; After the sodium chloride is fully dissolved, the stirring time is continued for 10 to 20 minutes, and the heat preservation reaction time after the stirring is completed is 24 to 48 hours.

9. The method for preparing antifreeze sea sand UHPC admixture based on seawater according to claim 4, characterized in that: In step S7, specifically: wait for the composite liquid in the reaction kettle to cool to 20-30°C, add the catalyst and triethanolamine at a speed of 180-220 r / min, stir evenly, and continue stirring for 15-30 minutes, increase the speed to 360-440 r / min, and then add 30% sodium hydroxide solution after speeding up.

10. The method for preparing antifreeze sea sand UHPC admixture based on seawater according to claim 4, characterized in that: In step S7, specifically: A fixed amount of 30% sodium hydroxide solution is added to the composite liquid each time, and after each addition, the mixture needs to be stirred at a speed of 360-440 r / min for at least 5 minutes; Determine the pH value of acidity and alkalinity; If the set pH value is not reached, a fixed amount of sodium hydroxide solution is added and the above operation is repeated; If the set pH value of 9 to 10 is reached, stop adding the 30% sodium hydroxide solution, continue stirring for 30 to 60 minutes, and check the pH value again until the pH value is 9 to 10, then stop stirring.