Quick-setting early-strength sea sand UHPC admixture prepared on basis of seawater and preparation method of quick-setting early-strength sea sand UHPC admixture

Abstract

The invention discloses a quick-setting early-strength sea sand UHPC admixture prepared based on seawater and a preparation method thereof.The admixture comprises polycarboxylic acid powder, a defoaming agent, concentrated pretreated seawater, anhydrous aluminum sulfate, triethanolamine and calcium lignosulphonate, and by adding the admixture into sea sand UHPC, solidification of the sea sand UHPC can be accelerated, and the early strength can be 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 quick-setting and early-strength 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 a seawater-based rapid-setting and early-strength sea sand UHPC admixture 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 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. In order to meet the requirements of UHPC rapid setting, early strength and other properties in actual projects, as well as the needs of special construction conditions or special environments, suitable admixtures are usually added, such as accelerators and early strength agents. Accelerators refer to admixtures added to UHPC that can make UHPC quickly solidify and harden. Early strength agents refer to admixtures that can improve the early strength of UHPC. They are mostly used in winter or emergency repairs.

[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, such as accelerators and early strength agents, are often required 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 produce high-performance sea sand UHPC has become an important technical problem that technicians in this field need to solve. Summary of the invention

[0005] The invention discloses a UHPC admixture for preparing rapid-setting and early-strength sea sand based on seawater. The admixture comprises the following components: polycarboxylic acid powder, a defoamer, concentrated pretreated seawater, anhydrous aluminum sulfate, triethanolamine and wood calcium.

[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 defoamer, 78 to 89 parts by weight of concentrated pretreated seawater, 10 to 22 parts by weight of anhydrous aluminum sulfate, 0.7 to 2.6 parts by weight of triethanolamine, and 3 to 8 parts by weight of wood calcium.

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

[0008] A method for preparing a rapid-setting and early-strength 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: raising the temperature of the concentrated pretreated seawater and maintaining a constant temperature after the temperature is raised;

[0012] Step S4: first adding anhydrous aluminum sulfate to the concentrated pretreated seawater, and stirring at a fixed speed;

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

[0014] Step S6: Increase the speed and keep it constant, then add the wood calcium, stir and dissolve it fully, and continue stirring until the temperature drops to 20-30°C;

[0015] Step S7: adding triethanolamine, and continuing stirring for 15 to 30 minutes after the triethanolamine is fully dissolved, and obtaining material B after the stirring is completed;

[0016] Step S8: 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.

[0017] Preferably, in step S3, the concentrated pretreated seawater is heated to 58-62° C. within 1 hour and maintained at a constant temperature.

[0018] Preferably, in step S8, the addition ratio of material B to material A is 1:3-10.

[0019] Preferably, in step S4, the fixed speed of stirring after the anhydrous aluminum sulfate is added is determined according to the diameter of the stirring barrel;

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

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

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

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

[0024] Preferably, in step S6, the increased rotation speed is determined according to the diameter of the mixing barrel;

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

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

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

[0028] After the wood calcium is fully dissolved by stirring, continue stirring at a speed of 180-220r / min until the temperature drops to 20-30℃.

[0029] Preferably, in step S7, after the triethanolamine is fully dissolved, the stirring speed during the stirring is 180-220 r / min.

[0030] The present invention provides a seawater-based preparation of a rapid-setting and early-strengthening sea sand UHPC admixture, the admixture includes polycarboxylic acid powder, defoamer, concentrated pretreated seawater, anhydrous aluminum sulfate, triethanolamine and wood calcium. By adding the admixture to the sea sand UHPC, the solidification of the sea sand UHPC can be accelerated and the early strength can be improved. In the preparation process, the present invention adopts the method of pretreating the seawater, further processing and adding various components to the concentrated pretreated seawater during compounding to generate a B material with rapid setting and early strength characteristics; adding A material to the B material, that is, through the 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, 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

[0031] The present invention discloses a UHPC admixture for preparing a rapid-setting and early-strength 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 rapid-setting and early-strength 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.

[0032] 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.

[0033] The invention provides a seawater-based preparation method for a rapid-setting and early-strength sea sand UHPC admixture. The admixture comprises the following components: polycarboxylic acid powder, a defoamer, concentrated pretreated seawater, anhydrous aluminum sulfate, triethanolamine and wood calcium.

[0034] 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, anhydrous aluminum sulfate, triethanolamine and wood calcium. These components are compounded with concentrated pretreated seawater to generate an admixture with rapid setting and early strength properties, so that the main components in the seawater are effectively utilized, greatly reducing the waste discharged into the natural environment.

[0035] 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 defoamer, 78 to 89 parts by weight of concentrated pretreated seawater, 10 to 22 parts by weight of anhydrous aluminum sulfate, 0.7 to 2.6 parts by weight of triethanolamine, and 3 to 8 parts by weight of wood calcium. The anhydrous aluminum sulfate, triethanolamine and wood calcium configured according to the formula of this embodiment are used with concentrated pretreated seawater to prepare a mixture with improved UHPC functionality. The mixture is added to the premix of sea sand UHPC to increase the strength by 10% to 50% in 3 days, 15% to 30% in 28 days, and 10% to 20% in grinding efficiency and fluidity. Moreover, the anti-bending, anti-seepage and anti-freezing properties are all improved, which can improve the quality of UHPC by one level while improving various properties.

[0036] 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.

[0037] A method for preparing a rapid-setting and early-strength sea sand UHPC admixture based on seawater comprises the following steps:

[0038] 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;

[0039] Step S2: taking polycarboxylic acid powder and defoaming agent and mixing them to obtain material A;

[0040] Step S3: raising the temperature of the concentrated pretreated seawater and maintaining a constant temperature after the temperature is raised;

[0041] Step S4: first adding anhydrous aluminum sulfate to the concentrated pretreated seawater, and stirring at a fixed speed;

[0042] Step S5: After the anhydrous aluminum sulfate is fully dissolved, continue stirring until the next step begins;

[0043] Step S6: Increase the speed and keep it constant, then add the wood calcium, stir and dissolve it fully, and continue stirring until the temperature drops to 20-30°C;

[0044] Step S7: adding triethanolamine, and continuing stirring for 15 to 30 minutes after the triethanolamine is fully dissolved, and obtaining material B after the stirring is completed;

[0045] Step S8: 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.

[0046] This preparation process treats seawater from two directions:

[0047] 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.).

[0048] Secondly, the adaptability of seawater admixtures and special materials is treated; anhydrous aluminum sulfate, triethanolamine and wood calcium are added to the concentrated and treated seawater after pretreatment, and added in steps to generate B material with rapid setting and early strength characteristics, so that it has the effect of improving early strength and accelerating solidification. Then, different proportions of A material are added to the B material, 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 B material that meets the durability and mechanical properties, and the working performance is controlled by adjusting the proportion of A material to prepare UHPC with various characteristics of excellent performance. It is often only necessary to adjust the components with the greatest influence in B material to configure different types of UHPC or UHPC premix admixtures.

[0049] 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.

[0050] The preparation method has the following advantages:

[0051] 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 fast-setting and early-strength sea sand UHPC admixtures, so as to achieve the effect of no subsequent environmental protection problems.

[0052] The performance of sea sand UHPC is improved; the admixture prepared by the preparation method is added to the sea sand UHPC premix to improve the 3-day strength by 10% to 50%, the 28-day strength by 15% to 30%, the grinding efficiency and fluidity by 10% to 20%, and the bending resistance, impermeability and frost resistance are all improved, which can improve the quality of sea sand UHPC by one level while improving various properties.

[0053] Preferably, in step S3, the concentrated pretreated seawater is heated to 58-62° C. within 1 hour and maintained at a constant temperature.

[0054] Preferably, in step S8, the addition ratio of material B to material A is 1:3-10.

[0055] Preferably, in step S4, the fixed speed of stirring after the anhydrous aluminum sulfate is added is determined according to the diameter of the stirring barrel;

[0056] When the diameter of the mixing barrel is less than 0.8 meters, the fixed speed is 300r / min;

[0057] When the diameter of the mixing barrel is 0.8 to 1.5 meters, the fixed speed is 400 to 450 r / min;

[0058] When the diameter of the mixing barrel is 1.5-2 meters, the fixed rotation speed is 600-650 r / min.

[0059] Preferably, in step S5, specifically: after the anhydrous aluminum sulfate is fully dissolved, stirring is continued at a speed of 270 to 330 r / min for 10 to 20 min until the next step begins.

[0060] Preferably, in step S6, the increased rotation speed is determined according to the diameter of the mixing barrel;

[0061] When the diameter of the mixing barrel is less than 0.8 meters, the fixed speed is 300r / min;

[0062] When the diameter of the mixing barrel is 0.8 to 1.5 meters, the increased speed is 400 to 450 r / min;

[0063] When the diameter of the mixing barrel is 1.5 to 2 meters, the increased speed is 600 to 650 r / min;

[0064] After the wood calcium is fully dissolved by stirring, continue stirring at a speed of 180-220r / min until the temperature drops to 20-30℃.

[0065] Preferably, in step S7, after the triethanolamine is fully dissolved, the stirring speed during the stirring is 180-220 r / min.

[0066] The following is described through multiple embodiments:

[0067] Embodiment 1:

[0068] 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;

[0069] 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;

[0070] Step S3: heating 78-89 parts by weight of concentrated pretreated seawater to 58-62° C. within 1 hour and maintaining the constant temperature;

[0071] Step S4: first adding 10 to 22 parts by weight of anhydrous aluminum sulfate to the concentrated pretreated seawater, and stirring at a fixed speed;

[0072] Step S5: After the anhydrous aluminum sulfate is fully dissolved, stirring is continued at a speed of 270 to 330 r / min for 10 to 20 min until the next step begins;

[0073] Step S6: Increase the speed and keep it constant, add 3 to 8 parts by weight of wood calcium, stir and dissolve fully, and then continue stirring at a speed of 180 to 220 r / min until the temperature drops to 20 to 30° C.;

[0074] Step S7: adding 0.7 to 2.6 parts by weight of triethanolamine, and continuing to stir at a speed of 180 to 220 r / min for 15 to 30 min after the triethanolamine is fully dissolved, and obtaining material B after the stirring is completed;

[0075] Step S8: 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.

[0076] Embodiment 2:

[0077] 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;

[0078] 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;

[0079] Step S3: heating 78 parts by weight of concentrated pretreated seawater to 58° C. within 1 hour and maintaining the constant temperature;

[0080] Step S4: first add 10 parts by weight of anhydrous aluminum sulfate to the concentrated pretreated seawater, and stir at a fixed speed;

[0081] Step S5: After the anhydrous aluminum sulfate is fully dissolved, stirring is continued at a speed of 270 r / min for 10 min until the next step begins;

[0082] Step S6: Increase the speed and keep it constant, add 3 parts by weight of wood calcium, stir and dissolve until fully dissolved, and then continue stirring at a speed of 180 r / min until the temperature drops to 20° C.;

[0083] Step S7: adding 0.7 to 2.6 parts by weight of triethanolamine, and continuing to stir at a speed of 180 r / min for 15 min after the triethanolamine is fully dissolved, and obtaining material B after the stirring is completed;

[0084] Step S8: 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.

[0085] Embodiment 3:

[0086] 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;

[0087] Step S2: 12.5 parts by weight of polycarboxylic acid powder and 0.135 parts by weight of defoaming agent are mixed and stirred to obtain material A;

[0088] Step S3: heating 83.5 parts by weight of concentrated pretreated seawater to 60° C. within 1 hour and maintaining the constant temperature;

[0089] Step S4: first adding 15.5 parts by weight of anhydrous aluminum sulfate to the concentrated pretreated seawater, and stirring at a fixed speed;

[0090] Step S5: After the anhydrous aluminum sulfate is fully dissolved, stirring is continued at a speed of 300 r / min for 15 min until the next step begins;

[0091] Step S6: Increase the speed and keep it constant, then add 3 to 8 parts by weight of wood calcium, stir and dissolve fully, and then continue stirring at a speed of 200 r / min until the temperature drops to 25°C;

[0092] Step S7: adding 1.65 parts by weight of triethanolamine, and stirring at a speed of 200 r / min for 22.5 min after the triethanolamine is fully dissolved, and obtaining material B after the stirring is completed;

[0093] Step S8: 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.

[0094] Embodiment 4:

[0095] 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;

[0096] 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;

[0097] Step S3: heating 89 parts by weight of concentrated pretreated seawater to 62° C. within 1 hour and maintaining the constant temperature;

[0098] Step S4: first adding 22 parts by weight of anhydrous aluminum sulfate to the concentrated pretreated seawater, and stirring at a fixed speed;

[0099] Step S5: After the anhydrous aluminum sulfate is fully dissolved, stirring is continued at a speed of 330 r / min for 20 min until the next step begins;

[0100] Step S6: Increase the speed and keep it constant, then add 3 to 8 parts by weight of wood calcium, stir and dissolve until fully dissolved, and then continue stirring at a speed of 220 r / min until the temperature drops to 30° C.;

[0101] Step S7: adding 0.7 to 2.6 parts by weight of triethanolamine, and continuing to stir at a speed of 220 r / min for 30 min after the triethanolamine is fully dissolved, and obtaining material B after the stirring is completed;

[0102] Step S8: 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.

[0103] The present invention provides a seawater-based preparation of a rapid-setting and early-strengthening sea sand UHPC admixture, the admixture includes polycarboxylic acid powder, defoamer, concentrated pretreated seawater, anhydrous aluminum sulfate, triethanolamine and wood calcium. By adding the admixture to the sea sand UHPC, the solidification of the sea sand UHPC can be accelerated and the early strength can be improved. In the preparation process, the present invention adopts the method of pretreating the seawater, further processing and adding various components to the concentrated pretreated seawater during compounding to generate a B material with rapid setting and early strength characteristics; adding A material to the B material, that is, through the 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, 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.

[0104] The above is a detailed introduction to the preparation of the rapid-setting and early-strength 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 a rapid-setting and early-strength sea sand UHPC admixture based on seawater, characterized in that: The additive comprises the following components: polycarboxylic acid powder, defoamer, concentrated pretreated seawater, anhydrous aluminum sulfate, triethanolamine and wood calcium.

2. The method for preparing a rapid-setting and early-strength 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 defoamer, 78 to 89 parts by weight of concentrated pretreated seawater, 10 to 22 parts by weight of anhydrous aluminum sulfate, 0.7 to 2.6 parts by weight of triethanolamine, and 3 to 8 parts by weight of wood calcium.

3. The method for preparing a rapid-setting and early-strength 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 a rapid-setting and early-strength 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: raising the temperature of the concentrated pretreated seawater and maintaining a constant temperature after the temperature is raised; Step S4: first adding anhydrous aluminum sulfate to the concentrated pretreated seawater, and stirring at a fixed speed; Step S5: After the anhydrous aluminum sulfate is fully dissolved, continue stirring until the next step begins; Step S6: Increase the speed and keep it constant, then add the wood calcium, stir and dissolve it fully, and continue stirring until the temperature drops to 20-30°C; Step S7: adding triethanolamine, and continuing stirring for 15 to 30 minutes after the triethanolamine is fully dissolved, and obtaining material B after the stirring is completed; Step S8: 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 a rapid-setting and early-strength sea sand UHPC admixture based on seawater according to claim 4, characterized in that: In step S3, the concentrated pretreated seawater is heated to 58-62°C within 1 hour and maintained at a constant temperature.

6. The method for preparing a rapid-setting and early-strength sea sand UHPC admixture based on seawater according to claim 4, characterized in that: In step S8: the addition ratio of material B to material A is 1:3-10.

7. The method for preparing a rapid-setting and early-strength sea sand UHPC admixture based on seawater according to claim 4, characterized in that: In step S4, the fixed speed of stirring after the addition of anhydrous aluminum sulfate is determined according to the diameter of the stirring barrel; When the diameter of the mixing barrel is less than 0.8 meters, the fixed speed is 300r / min; When the diameter of the mixing barrel is 0.8 to 1.5 meters, the fixed speed is 400 to 450 r / min; When the diameter of the mixing barrel is 1.5-2 meters, the fixed rotation speed is 600-650 r / min.

8. The method for preparing a rapid-setting and early-strength sea sand UHPC admixture based on seawater according to claim 4, characterized in that: In step S5, specifically, after the anhydrous aluminum sulfate 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.

9. The method for preparing a rapid-setting and early-strength sea sand UHPC admixture based on seawater according to claim 4, characterized in that: In step S6, the increased rotation speed is determined according to the diameter of the mixing barrel; When the diameter of the mixing barrel is less than 0.8 meters, the fixed speed is 300r / min; When the diameter of the mixing barrel is 0.8 to 1.5 meters, the increased speed is 400 to 450 r / min; When the diameter of the mixing barrel is 1.5 to 2 meters, the increased speed is 600 to 650 r / min; After the wood calcium is fully dissolved by stirring, continue stirring at a speed of 180-220r / min until the temperature drops to 20-30℃.

10. The method for preparing a rapid-setting and early-strength sea sand UHPC admixture based on seawater according to claim 4, characterized in that: In step S7, after the triethanolamine is fully dissolved, the stirring speed is continued to be 180-220 r / min.