An admixture for high self-compacting performance concrete of rockfill dam and a preparation method thereof

Abstract

The application discloses an additive for high self-compacting performance concrete of a rock-fill dam and a preparation method thereof, and belongs to the technical field of concrete additives. The additive for high self-compacting performance concrete of the rock-fill dam provided by the application comprises the following raw materials in parts by weight: dispersing component A 550-600 parts, water-retaining and self-maintaining component B 60-100 parts, enhancing component C 100-140 parts, shrinkage-reducing component D 30-60 parts, anti-permeation component E 100-150 parts and water 0-110 parts. The additive for high self-compacting performance concrete of the rock-fill dam provided by the application can significantly improve the working performance, early and later mechanical properties and durability (anti-shrinkage and anti-permeation) of the high self-compacting concrete.

Description

Technical Field

[0001] This invention belongs to the field of concrete admixture technology, and particularly relates to an admixture for high self-compacting concrete for rockfill dams and its preparation method. Background Technology

[0002] With the introduction of rockfill concrete dam construction technology, the "large rockfill + high self-compacting concrete (HSCC)" casting and bonding method has broken through the constraints of traditional continuous gradation compaction theory. Rockfill concrete combines the advantages of self-compacting concrete and masonry, making full use of a large amount of rock, significantly reducing cement usage, increasing concrete density, reducing heat of hydration, and reducing shrinkage, thereby eliminating the need for vibration or rolling processes and temperature control measures such as cooling water pipes. The simplified construction process significantly reduces equipment requirements and labor input, accelerates construction progress, and reduces construction costs, making it a new environmentally friendly dam construction technology. Rockfill dam concrete is a heterogeneous material composed of large rockfill and high self-compacting concrete. The rockfill generally requires a particle size of 300mm or more, while the high self-compacting concrete mainly contains small stones, sand, admixtures (fly ash or stone powder, etc.), cement paste, and additives. Compared to conventional self-compacting concrete, high self-compacting performance concrete (HSCC) is characterized by low binder content and high admixture content (such as fly ash or stone powder), thus placing higher demands on fluidity, segregation resistance, and stability.

[0003] Polycarboxylate superplasticizers, characterized by high water reduction, high slump retention, and low admixture dosage, are widely used in the concrete industry. However, due to the low binder content and high admixture (fly ash or stone powder, etc.) content of high self-compacting concrete (HSCC), polycarboxylate superplasticizers with high water reduction rates and strong dispersibility can easily lead to poor stability, segregation, bleeding, low early strength, and slow strength gain in HSCC, severely affecting the pouring and use of concrete. Early rockfill concrete dams used conventional concrete for their seepage barriers; currently, to simplify processes and improve construction speed, most projects have switched to integrated pouring technology for HSCC. This places higher demands on the crack resistance, shrinkage resistance, and impermeability of HSCC itself, and ordinary polycarboxylate superplasticizers can no longer meet the performance requirements of HSCC in on-site processes.

[0004] Therefore, the preparation of an admixture that can improve the workability, early and late mechanical properties and durability of high self-compacting concrete is of great significance for the application and development of high self-compacting concrete in rockfill concrete dam construction technology. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an admixture for high self-compacting concrete in rockfill dams and its preparation method. The admixture provided by this invention can significantly improve the workability, early and late-stage mechanical properties, and durability (shrinkage resistance and impermeability) of high self-compacting concrete.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides an admixture for high self-compacting concrete in rockfill dams, comprising the following raw materials in parts by weight: dispersing component A 550-600 parts, water-retaining and self-curing component B 60-100 parts, reinforcing component C 100-140 parts, shrinkage-reducing component D 30-60 parts, impermeable component E 100-150 parts, and water 0-110 parts;

[0008] The dispersion component A is polymerized from macromonomers and small monomers, wherein the macromonomer is hydroxybutyl vinyl polyethylene glycol ether, and the small monomers are maleic anhydride, vinyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate; the water-retaining and self-maintaining component B is composed of xanthan gum and maintenance component B1; the reinforcing component C is a mixture containing nano-calcium carbonate; the shrinkage-reducing component D is a mixture containing nano-cellulose; and the impermeability-resistant component E is a mixture containing fatty acid salts and nano-silica.

[0009] Technical Principle: The dispersing component A of the admixture for high self-compacting concrete in rockfill dams, prepared in this invention, is a dispersant synthesized from hydroxybutyl vinyl polyethylene glycol ether (VPEG) macromonomers and small monomers. Compared to conventional macromonomers such as methyl allyl polyoxyethylene ether (HPEG), isopentenyl polyoxyethylene ether (TPEG), and vinyl diethylene glycol ether (GPEG), VPEG side chains contain more hydrophobic groups, making it easier to generate stable, dense, and fine bubbles during concrete mixing. This results in lower and smoother concrete paste viscosity, leading to better concrete fluidity and easier filling of voids between rocks. The small monomers, maleic anhydride, vinyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate, can hydrolyze in the alkaline environment of cement, effectively maintaining the workability of the concrete. Compared to traditional slump-retaining mother liquor, its slump retention curve is more stable, and the concrete is less prone to bleeding and loss during the process. The water-retaining and self-curing component B plays a self-curing role. After the high self-compacting concrete is poured, due to temperature changes and the relatively thick pouring thickness (usually 1.5~2 mm), the concrete retains its slump. The bottom layer of concrete is difficult to cure properly, resulting in cracks due to rapid water loss. The water-retaining self-curing component B, composed of xanthan gum and curing component B1, has a macromolecular network structure that can lock in free water in the cement paste and adsorb onto the concrete surface to form a hydrophobic film, reducing water evaporation loss and minimizing drying shrinkage during early hydration of high self-compacting concrete. The reinforcing component C contains nano-sized calcium carbonate, providing anchoring points for the formation of ettringite during early cement hydration of high self-compacting concrete, promoting rapid formation of the early hydration product ettringite, and providing a calcium source for ettringite, thus promoting denser hydration in later stages and supporting the increase in concrete strength. The shrinkage-reducing component D mainly utilizes nano-sized cellulose to generate stable, uniform, and fine bubbles during concrete mixing. Furthermore, due to the network structure of nano-cellulose, the generated bubbles are more stable, resulting in less air loss over time. The impermeable component E has a double-layer impermeability; on the one hand, the fatty acid salts contained in the component can react with the calcium in the concrete... 2+ The process generates hydrophobic calcium fatty acid precipitates, which seal the internal pores of the concrete, preventing water from wetting and penetrating the concrete. On the other hand, the anti-seepage component also contains active nano-silica, which can penetrate the bedrock surface and generate new crystals, preventing water from seeping through the interface between the high self-compacting concrete and the bedrock. Ultimately, an admixture for high self-compacting concrete in rockfill dams was obtained, which can significantly improve the workability, early and late mechanical properties, and durability (shrinkage resistance and impermeability) of high self-compacting concrete.

[0010] Further, the preparation method of the dispersion component A includes the following steps: adding an initiator to a mixed solution of hydroxybutyl vinyl polyethylene glycol ether and water to carry out a polymerization reaction, then adding solution a and solution b dropwise, continuing the reaction after the dropwise addition is completed, then cooling the reaction system to room temperature, and then adjusting the system concentration with water to obtain the dispersion component A;

[0011] The weight ratio of the hydroxybutyl vinyl polyethylene glycol ether to water is (320~400):(250~350).

[0012] By weight, the initiator consists of 4-6 parts hydrogen peroxide and 1-3 parts ferrous sulfate solution; solution a consists of 30 parts acrylic acid, 10-20 parts maleic anhydride, 2-4 parts vinyl methacrylate, 4-6 parts hydroxyethyl acrylate, 6-10 parts hydroxypropyl acrylate, and 100 parts water; solution b consists of 1.5 parts sodium formaldehyde sulfoxylate, 2 parts mercaptopropionic acid, and 120 parts water.

[0013] The polymerization reaction temperature is 8~12℃; the dropwise addition time of solution a and solution b is 1~3h; and the reaction time after the dropwise addition is 60~120min.

[0014] Furthermore, the weight-average molecular weight M of the dispersed component A w The value is 30,000~34,000 g / mol.

[0015] Further, the preparation method of the water-retaining self-maintaining component B includes the following steps: water, sodium dodecyl sulfate, sodium lauryl ether sulfate, sodium tetradecyl sulfate and surfactant are mixed evenly and heated, then solution c and solution d are added dropwise, the temperature is maintained after the dropwise addition is completed, the reaction system is then cooled to room temperature, and then ammonia water is added to obtain maintenance component B1; the maintenance component B1 and xanthan gum are stirred and mixed evenly to obtain the water-retaining self-maintaining component B;

[0016] By weight, solution c consists of 80-120 parts ethyl methacrylate, 50-70 parts butyl acrylate, 20-40 parts methacrylic acid, 20-30 parts styrene, and 8-12 parts ethylene glycol ethyl ether; solution d consists of 4-6 parts ammonium persulfate and 120 parts water.

[0017] The temperature is raised to 75~85℃; the dripping time of solution c and solution d is 1~3h; the holding time after the dripping is completed is 1h.

[0018] Further, the weight ratio of water, sodium dodecyl sulfate, sodium lauryl ether sulfate, sodium tetradecyl sulfate and surfactant is (450~550):(15~25):(5~15):(3~7):(45~55); the weight ratio of maintenance component B1 and xanthan gum is 800:(1~3).

[0019] Further, the preparation method of the reinforcing component C includes the following steps: under the conditions of a temperature of 55~65℃ and a rotation speed of 3000~8000r / min, solution e and solution f are added dropwise to a mixed solution of calcium nitrate tetrahydrate and water, and stirring is continued after the addition is completed to obtain the reinforcing component C;

[0020] The weight ratio of the tetrahydrate calcium nitrate to water is (120~160):(350~450).

[0021] By weight, solution e consists of 1 part xanthan gum, 1-3 parts diethanolamine, 1-3 parts citric acid, and 500 parts water; solution f consists of 15-25 parts sodium carbonate and 200 parts water.

[0022] The addition time for liquids e and f is 3 hours; the stirring time after the addition is completed is 2 hours.

[0023] Further, by weight, the shrinkage-reducing component D consists of 15-25 parts nanocellulose, 2-4 parts triterpenoid saponin solution, 0.5 parts polyether defoamer, 0.5 parts organosilicon defoamer, and 100 parts water.

[0024] Further, the preparation method of the antipermeability component E includes the following steps: under the conditions of a temperature of 65~75℃ and a rotation speed of 260~300r / min, a mixture of stearic acid and oleic acid is stirred and dissolved, the temperature is kept constant, the rotation speed is changed to 1500r / min, NaOH solution is added dropwise, after the system is cooled to room temperature after the addition is completed, g solution and h solution are added dropwise at a rotation speed of 1500r / min, and stirring is continued after the addition is completed to obtain the antipermeability component E;

[0025] The weight ratio of stearic acid, oleic acid and NaOH solution is (45~55):(45~55):(80~120).

[0026] By weight, the g solution consists of 1 part xanthan gum and 500 parts water; the h solution consists of 15-25 parts silane coupling agent, 15-25 parts diethanolamine, 80-120 parts nano silica and 400 parts water.

[0027] The NaOH solution is added dropwise over a period of 1 to 3 hours; the g solution and h solution are added dropwise over a period of 2 to 4 hours; and stirring continues for 2 hours after the addition is completed.

[0028] The present invention provides a method for preparing an admixture for high self-compacting concrete for rockfill dams as described in the above technical solution, comprising: mixing a dispersing component A, a water-retaining and self-curing component B, a reinforcing component C, a shrinkage-reducing component D, an anti-seepage component E, and water evenly to obtain the admixture for high self-compacting concrete for rockfill dams.

[0029] The present invention also provides the application of the admixture for high self-compacting performance concrete for rockfill dams as described in the above technical solution in the preparation of high self-compacting performance concrete for rockfill dams.

[0030] Compared with the prior art, the present invention has the following advantages and technical effects:

[0031] The admixture for high self-compacting concrete in rockfill dams provided by this invention can significantly improve the workability, early and late mechanical properties, and durability (shrinkage resistance and permeability resistance) of high self-compacting concrete. The high self-compacting concrete prepared using the admixture provided by this invention has small slump, spread, and air content loss after 1 hour, short T500 and V-shaped funnel time, small time growth after 1 hour, small shrinkage rate and permeability coefficient at 7 days and 28 days, and high compressive strength at 7 days and 28 days. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to specific embodiments.

[0034] This invention provides an admixture for high self-compacting concrete in rockfill dams, comprising the following raw materials in parts by weight: dispersing component A 550-600 parts, water-retaining and self-curing component B 60-100 parts, reinforcing component C 100-140 parts, shrinkage-reducing component D 30-60 parts, impermeable component E 100-150 parts, and water 0-110 parts.

[0035] In a preferred embodiment, the dispersion component A is polymerized from macromonomers and small monomers. The macromonomer is hydroxybutyl vinyl polyethylene glycol ether (VPEG), and the small monomers are maleic anhydride, vinyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate. Dispersion component A in this invention is synthesized from hydroxybutyl vinyl polyethylene glycol ether (VPEG) macromonomers and small monomers. Compared to conventional macromonomers such as methyl allyl polyoxyethylene ether (HPEG), isopentenyl polyoxyethylene ether (TPEG), and vinyl diethylene glycol ether (GPEG), VPEG side chains contain more hydrophobic groups, making it easier to generate stable, dense, and fine bubbles during concrete mixing. This results in lower and smoother concrete paste viscosity, leading to better concrete fluidity and easier filling of voids between aggregates. The maleic anhydride, vinyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate in the small monomers can hydrolyze in the alkaline environment of cement, effectively maintaining the workability of the concrete. Compared to traditional slump-retaining mother liquor, its slump retention curve is more stable, and the concrete is less prone to bleeding and loss during mixing.

[0036] In a preferred embodiment, the preparation method of the dispersion component A includes the following steps: adding an initiator to a mixed solution of hydroxybutyl vinyl polyethylene glycol ether and water to carry out a polymerization reaction, then adding solution a and solution b dropwise, continuing the reaction after the dropwise addition is completed, then cooling the reaction system to room temperature, and then adjusting the system concentration with water to obtain the dispersion component A.

[0037] In a preferred embodiment, the weight ratio of the hydroxybutyl vinyl polyethylene glycol ether to water is (320~400):(250~350).

[0038] In a preferred embodiment, the initiator is composed of 4-6 parts by weight of hydrogen peroxide and 1-3 parts by weight of ferrous sulfate solution; the concentration of the ferrous sulfate solution is 1 wt.%.

[0039] In a preferred embodiment, the polymerization reaction is carried out at a temperature of 8-12°C.

[0040] In a preferred embodiment, liquid a is composed of 30 parts acrylic acid, 10-20 parts maleic anhydride, 2-4 parts ethylene methacrylate, 4-6 parts hydroxyethyl acrylate, 6-10 parts hydroxypropyl acrylate and 100 parts water by weight.

[0041] In a preferred embodiment, solution b consists of 1.5 parts of sodium formaldehyde sulfoxylate, 2 parts of mercaptopropionic acid, and 120 parts of water by weight.

[0042] In a preferred embodiment, the dropwise addition time of solution a and solution b is 1-3 hours; the reaction time after the dropwise addition is 60-120 minutes.

[0043] In a preferred embodiment, the system concentration is adjusted to 40 wt.% using water.

[0044] In a preferred embodiment, the weight-average molecular weight (M) of the dispersed component A is... w The concentration is 30,000~34,000 g / mol.

[0045] In a preferred embodiment, the water-retaining self-curing component B is composed of xanthan gum and curing component B1. The water-retaining self-curing component B in this invention plays a self-curing role. After the high self-compacting concrete is poured, due to temperature differences and the relatively thick pouring thickness (usually 1.5~2m), the bottom layer of concrete is difficult to cure properly, resulting in cracks caused by rapid water loss. The water-retaining self-curing component B, composed of xanthan gum and curing component B1, has a macromolecular network structure that can lock in free water in the cement paste and adsorb onto the concrete surface to form a hydrophobic film, reducing water evaporation loss from the concrete surface and minimizing drying shrinkage caused by water evaporation during the early hydration process of the high self-compacting concrete.

[0046] In a preferred embodiment, the preparation method of the water-retaining self-maintaining component B includes the following steps: water, sodium dodecyl sulfate, sodium lauryl ether sulfate, sodium tetradecyl sulfate and surfactant are mixed evenly and heated, then solution c and solution d are added dropwise, the temperature is maintained after the dropwise addition is completed, the reaction system is then cooled to room temperature, and then ammonia is added to obtain maintenance component B1; the maintenance component B1 and xanthan gum are stirred and mixed evenly to obtain the water-retaining self-maintaining component B.

[0047] In a preferred embodiment, the weight ratio of water, sodium dodecyl sulfate, sodium lauryl ether sulfate, sodium tetradecyl sulfate, and surfactant is (450~550):(15~25):(5~15):(3~7):(45~55); the surfactant is EFS4070, purchased from Shanghai Zhongcheng Fine Chemical Co., Ltd.

[0048] In a preferred embodiment, the temperature is increased to 75~85°C.

[0049] In a preferred embodiment, the addition of liquid c and liquid d is accompanied by stirring; the stirring speed is 200~240 r / min.

[0050] In a preferred embodiment, liquid c is composed of 80-120 parts by weight of ethyl methacrylate, 50-70 parts by weight of butyl acrylate, 20-40 parts by weight of methacrylic acid, 20-30 parts by weight of styrene and 8-12 parts by weight of ethylene glycol ethyl ether.

[0051] In a preferred embodiment, the d solution consists of 4 to 6 parts by weight of ammonium persulfate and 120 parts by weight of water.

[0052] In a preferred embodiment, the dripping time of liquid c and liquid d is 1-3 hours; the heat preservation time after the dripping is completed is 1 hour.

[0053] In a preferred embodiment, the concentration of the ammonia water is 0.1 mol / L; based on the amount of sodium dodecyl sulfate used being 15-25 parts by weight, the amount of ammonia water used is 30 parts.

[0054] In a preferred embodiment, the weight ratio of the maintenance component B1 to xanthan gum is 800:(1~3).

[0055] In a preferred embodiment, the maintenance component B1 and xanthan gum are stirred and mixed evenly at a speed of 500 r / min for 30 min.

[0056] In a preferred embodiment, the reinforcing component C is a mixture containing nano-calcium carbonate. The reinforcing component C in this invention provides anchoring sites for the early cement hydration of high self-compacting concrete to form ettringite, promoting the rapid formation of the early hydration product ettringite. Simultaneously, it provides a calcium source for the ettringite hydration product, resulting in denser hydration of the concrete in the later stages, thus supporting the increase in the later strength of the concrete.

[0057] In a preferred embodiment, the preparation method of the reinforcing component C includes the following steps: adding solution e and solution f dropwise to a mixed solution of calcium nitrate tetrahydrate and water at a temperature of 55-65°C and a rotation speed of 3000-8000 r / min. After the addition is complete, stirring continues to obtain the reinforcing component C. In this invention, calcium nitrate tetrahydrate and sodium carbonate in solution f undergo a co-precipitation reaction. By controlling the reaction temperature, rotation speed, solution concentration, and dropwise addition time of solution f, the nucleation process of nano-calcium carbonate is promoted, while the growth of calcium carbonate into large particles is inhibited, thus obtaining nano-calcium carbonate. Therefore, the reinforcing component C contains nano-calcium carbonate.

[0058] In a preferred embodiment, the weight ratio of the calcium nitrate tetrahydrate to water is (120~160):(350~450).

[0059] In a preferred embodiment, the e-liquid, by weight, consists of 1 part xanthan gum, 1-3 parts diethanolamine, 1-3 parts citric acid, and 500 parts water.

[0060] In a preferred embodiment, the f liquid is composed of 15-25 parts sodium carbonate and 200 parts water by weight; the f liquid is prepared by mixing sodium carbonate and water and stirring at 5000 r / min for 30 min.

[0061] In a preferred embodiment, the dripping time for liquid e and liquid f is 3 hours; and the stirring time continues for 2 hours after the dripping is completed.

[0062] In a preferred embodiment, the shrinkage-reducing component D is a mixture containing nano-cellulose. The shrinkage-reducing component D in this invention mainly utilizes nano-cellulose to generate stable, uniform, and fine bubbles during concrete mixing. Furthermore, because nano-cellulose has a network structure, the generated bubbles are more stable, resulting in less air content loss in the concrete over time.

[0063] In a preferred embodiment, the shrinkage-reducing component D, by weight, comprises 15-25 parts nanocellulose, 2-4 parts triterpenoid saponin solution, 0.5 parts polyether defoamer, 0.5 parts organosilicon defoamer, and 100 parts water; the triterpenoid saponin solution was purchased from Shandong Xinbaihe Chemical Technology Co., Ltd., model ST05; the polyether defoamer was purchased from Xiamen Ruikeman Chemical Technology Co., Ltd., model RK-1805S; and the organosilicon defoamer was purchased from Xiamen Ruikeman Chemical Technology Co., Ltd., model RK-325G.

[0064] In a preferred embodiment, the anti-seepage component E, by weight, is a mixture containing fatty acid salts and nano-silica. The anti-seepage component E of this invention possesses dual-layer anti-seepage properties; on the one hand, the fatty acid salts contained in the component can react with Ca in concrete... 2+ The formation of hydrophobic fatty acid calcium precipitates blocks the internal pores of the concrete, preventing water from wetting and penetrating the interior of the concrete. On the other hand, the anti-seepage component also contains active nano-silica, which can penetrate the surface of the bedrock and produce new crystals, preventing water from seeping through the interface between the high self-compacting concrete and the bedrock.

[0065] In a preferred embodiment, the preparation method of the antipermeability component E includes the following steps: At a temperature of 65-75°C and a rotation speed of 260-300 r / min, a mixture of stearic acid and oleic acid is stirred and dissolved. While maintaining the temperature, the rotation speed is changed to 1500 r / min. NaOH solution is added dropwise. After the addition is complete and the system cools to room temperature, solution g and solution h are simultaneously added dropwise at 1500 r / min. Stirring continues after the addition is complete to obtain the antipermeability component E. In this invention, stearic acid, oleic acid, and sodium hydroxide react through a saponification reaction to produce fatty acid salts; therefore, the antipermeability component E contains fatty acid salts.

[0066] In a preferred embodiment, the weight ratio of stearic acid, oleic acid and NaOH solution is (45~55):(45~55):(80~120).

[0067] In a preferred embodiment, the mixture of stearic acid and oleic acid is stirred and dissolved for 30 minutes.

[0068] In a preferred embodiment, the concentration of the NaOH solution is 30 wt.%; and the dropping time of the NaOH solution is 1-3 h.

[0069] In a preferred embodiment, the liquid g consists of 1 part xanthan gum and 500 parts water by weight.

[0070] In a preferred embodiment, the h liquid is composed of 15-25 parts by weight of silane coupling agent, 15-25 parts by weight of diethanolamine, 80-120 parts by weight of nano-silica and 400 parts by weight of water; the silane coupling agent is purchased from Henan Jijia Chemical Products Co., Ltd., and the model is KH-570.

[0071] In a preferred embodiment, the dropping time of liquid g and liquid h is 2-4 hours; the stirring time after the dropping is completed is 2 hours.

[0072] In a preferred embodiment of the present invention, all water used is deionized water.

[0073] The present invention provides a method for preparing an admixture for high self-compacting concrete for rockfill dams as described in the above technical solution, comprising: mixing a dispersing component A, a water-retaining and self-curing component B, a reinforcing component C, a shrinkage-reducing component D, an anti-seepage component E, and water evenly to obtain the admixture for high self-compacting concrete for rockfill dams.

[0074] The present invention also provides the application of the admixture for high self-compacting performance concrete for rockfill dams as described in the above technical solution in the preparation of high self-compacting performance concrete for rockfill dams.

[0075] Unless otherwise specified, all parts in this invention represent "parts by weight".

[0076] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels.

[0077] In the following examples and comparative examples, the triterpenoid saponin solution was purchased from Shandong Xinbaihe Chemical Technology Co., Ltd., model ST05; the polyether defoamer was purchased from Xiamen Ruikeman Chemical Technology Co., Ltd., model RK-1805S; the organosilicon defoamer was purchased from Xiamen Ruikeman Chemical Technology Co., Ltd., model RK-325G; the silane coupling agent was purchased from Henan Jijia Chemical Products Co., Ltd., model KH-570; and the viscosity of xanthan gum was 200,000 mPa·s.

[0078] Example 1

[0079] An admixture for high self-compacting concrete in rockfill dams is composed of the following raw materials in parts by weight: 550 parts of dispersing component A, 60 parts of water-retaining and self-curing component B, 100 parts of reinforcing component C, 30 parts of shrinkage-reducing component D, 150 parts of impermeable component E, and 110 parts of deionized water.

[0080] The preparation method of dispersion component A is as follows: 320 parts of hydroxybutyl vinyl polyethylene glycol ether (VPEG3000) and 250 parts of deionized water are added to a reactor equipped with a stirrer, a dropping device, and a heating device. The reactor temperature is set to 8℃ and the rotation speed is set to 280 r / min. Then, an initiator composed of 4 parts of hydrogen peroxide and 1 part of ferrous sulfate solution (concentration of 1 wt.%) is added. Subsequently, solutions a and b are added dropwise (solution a consists of 30 parts of acrylic acid, 10 parts of maleic anhydride, 2 parts of vinyl methacrylate, 4 parts of hydroxyethyl acrylate, 6 parts of hydroxypropyl acrylate, and 100 parts of deionized water; solution b consists of 1.5 parts of sodium formaldehyde sulfoxylate (E51), 2 parts of mercaptopropionic acid, and 120 parts of deionized water). The dropwise addition time is 1 h. After the dropwise addition is completed, the reaction continues for 60 min. After the reaction is completed, the temperature of the system is lowered to room temperature, and the system concentration is adjusted to 40 wt.% with deionized water to obtain dispersion component A. The weight-average molecular weight M of dispersion component A is determined by gel permeation chromatography. w The concentration was 30859 g / mol, with a conversion rate of 93%.

[0081] The preparation method of water-retaining self-maintaining component B is as follows: Add 450 parts deionized water, 15 parts sodium dodecyl sulfate, 5 parts sodium lauryl ether sulfate, 3 parts sodium tetradecyl sulfate, and 45 parts EFS4070 (purchased from Shanghai Zhongcheng Fine Chemical Co., Ltd.) to a reactor equipped with a stirrer, a dropping device, a reflux device, and a heating device. After stirring evenly, raise the temperature to 75℃, set the rotation speed to 200 r / min, and begin dropping in solution c and solution d (solution c consists of 80 parts ethyl methacrylate, 50 parts butyl acrylate, and 20...). The first solution consists of 1 part methacrylic acid, 20 parts styrene, and 8 parts ethylene glycol ethyl ether; solution d consists of 4 parts ammonium persulfate and 120 parts deionized water. The dropwise addition time is 1 hour, and after the dropwise addition is completed, the temperature of the reaction system is kept at 1 hour. Then, the temperature of the reaction system is lowered to room temperature, and 30 parts ammonia water (concentration of 0.1 mol / L) is added. After stirring evenly, the curing component B1 is obtained. 800 parts of the above curing component B1 and 1 part xanthan gum are mixed and stirred at 500 r / min for 30 min to obtain water-retaining self-curing component B.

[0082] The preparation method of reinforcing component C is as follows: 120 parts of calcium nitrate tetrahydrate and 350 parts of deionized water are added to a reactor equipped with a high-speed stirrer, a dropping device and a heating device. The reactor temperature is set to 55℃ and the rotation speed is set to 3000 r / min. Solution e and solution f (solution e consists of 1 part xanthan gum, 1 part diethanolamine, 1 part citric acid and 500 parts deionized water; solution f is prepared by stirring 15 parts sodium carbonate and 200 parts deionized water at a speed of 5000 r / min for 30 min) are added dropwise over 3 h. After the addition is completed, stirring is continued for 2 h to obtain milky white reinforcing component C.

[0083] Shrinkage reduction component D consists of 15 parts nanocellulose (purchased from Wuhan Huaxiang Kejie Biotechnology Co., Ltd.), 2 parts triterpenoid saponin air-entraining agent solution (concentration of 40 wt.%), 0.5 parts polyether defoamer, 0.5 parts organosilicon defoamer and 100 parts deionized water;

[0084] The preparation method of antipermeability component E is as follows: 45 parts of stearic acid and 45 parts of oleic acid are added to a reactor equipped with a high-speed stirrer, a dropping device, and a heating device. The reactor temperature is set to 65℃, the stirring speed is set to 260 r / min, and after stirring for 30 min to fully dissolve, the temperature is kept constant, the stirring speed is changed to 1500 r / min, and 80 parts of NaOH solution (concentration of 30 wt.%) are added dropwise to the reactor. After 1 h of dropwise addition, an emulsion liquid is obtained. After the emulsion liquid cools to room temperature, solution g and solution h are added dropwise simultaneously at a stirring speed of 1500 r / min. Solution g is composed of 1 part xanthan gum and 500 parts deionized water stirred evenly in a high-speed stirrer; solution h is composed of 15 parts silane coupling agent, 15 parts diethanolamine, 80 parts nano silica, and 400 parts deionized water. The dropwise addition time is 2 h, and after the dropwise addition is completed, stirring is continued for 2 h to obtain milky white antipermeability component E.

[0085] The preparation method of the above-mentioned admixture for high self-compacting performance concrete of rockfill dams is as follows: mix the dispersing component A, water-retaining self-curing component B, reinforcing component C, shrinkage-reducing component D, impermeable component E and water evenly to obtain the admixture for high self-compacting performance concrete of rockfill dams.

[0086] Example 2

[0087] An admixture for high self-compacting concrete for rockfill dams is composed of the following raw materials in parts by weight: 600 parts of dispersing component A, 100 parts of water-retaining and self-curing component B, 140 parts of reinforcing component C, 60 parts of shrinkage-reducing component D, 100 parts of impermeable component E, and 0 parts of deionized water.

[0088] The preparation method of dispersion component A is as follows: 400 parts of hydroxybutyl vinyl polyethylene glycol ether (VPEG3000) and 350 parts of deionized water are added to a reactor equipped with a stirrer, a dropping device, and a heating device. The reactor temperature is set to 12℃ and the rotation speed is set to 350 r / min. Then, an initiator composed of 6 parts of hydrogen peroxide and 3 parts of ferrous sulfate solution (concentration of 1 wt.%) is added. Subsequently, solutions a and b are added dropwise (solution a consists of 30 parts of acrylic acid, 20 parts of maleic anhydride, 4 parts of vinyl methacrylate, 6 parts of hydroxyethyl acrylate, 10 parts of hydroxypropyl acrylate, and 100 parts of deionized water; solution b consists of 1.5 parts of sodium formaldehyde sulfoxylate (E51), 2 parts of mercaptopropionic acid, and 120 parts of deionized water). The dropwise addition time is 3 h. After the dropwise addition is completed, the reaction continues for 120 min. After the reaction is completed, the temperature of the system is lowered to room temperature, and the system concentration is adjusted to 40 wt.% with deionized water to obtain dispersion component A. The weight-average molecular weight M of dispersion component A is determined by gel permeation chromatography. w The concentration was 33865 g / mol, with a conversion rate of 95%.

[0089] The preparation method of water-retaining self-maintaining component B is as follows: Add 550 parts deionized water, 25 parts sodium dodecyl sulfate, 15 parts sodium lauryl ether sulfate, 7 parts sodium tetradecyl sulfate, and 55 parts EFS4070 (purchased from Shanghai Zhongcheng Fine Chemical Co., Ltd.) to a reactor equipped with a stirrer, a dropping device, a reflux device, and a heating device. After stirring evenly, raise the temperature to 85℃, set the rotation speed to 240 r / min, and begin dropping in solution c and solution d (solution c consists of 120 parts ethyl methacrylate, 70 parts butyl acrylate, and 4...). The reaction mixture consists of 0 parts methacrylic acid, 30 parts styrene, and 12 parts ethylene glycol ethyl ether; solution d consists of 6 parts ammonium persulfate and 120 parts deionized water. The addition time is 3 hours, and the mixture is kept warm for 1 hour after the addition is completed. Then, the temperature of the reaction system is lowered to room temperature, and 30 parts ammonia water (concentration of 0.1 mol / L) is added. After stirring evenly, the curing component B1 is obtained. 800 parts of the above curing component B1 and 3 parts xanthan gum are mixed and stirred at 500 r / min for 30 minutes to obtain water-retaining self-curing component B.

[0090] The preparation method of reinforcing component C is as follows: 160 parts of calcium nitrate tetrahydrate and 450 parts of deionized water are added to a reactor equipped with a high-speed stirrer, a dropping device, and a heating device. The reactor temperature is set to 65℃ and the rotation speed is set to 8000 r / min. Solution e and solution f (solution e consists of 1 part xanthan gum, 3 parts diethanolamine, 3 parts citric acid, and 500 parts deionized water; solution f is prepared by stirring 25 parts sodium carbonate and 200 parts deionized water at a speed of 5000 r / min for 30 min) are added dropwise over a period of 3 h. After the addition is completed, stirring is continued for 2 h to obtain milky white reinforcing component C.

[0091] Shrinkage reduction component D consists of 25 parts nanocellulose (purchased from Wuhan Huaxiang Kejie Biotechnology Co., Ltd.), 4 parts triterpenoid saponin air-entraining agent solution (concentration of 40 wt.%), 0.5 parts polyether defoamer, 0.5 parts organosilicon defoamer and 100 parts deionized water;

[0092] The preparation method of antipermeability component E is as follows: 55 parts of stearic acid and 55 parts of oleic acid are added to a reactor equipped with a high-speed stirrer, a dropping device, and a heating device. The reactor temperature is set to 75℃, the stirring speed is set to 300 r / min, and the mixture is stirred for 30 min until fully dissolved. After the temperature is kept constant, the stirring speed is changed to 1500 r / min, and 120 parts of NaOH solution (concentration of 30 wt.%) is added dropwise to the reactor. After 3 h of dropwise addition, an emulsion liquid is obtained. After the emulsion liquid cools to room temperature, solution g and solution h are added dropwise simultaneously at a stirring speed of 1500 r / min. Solution g is composed of 1 part xanthan gum and 500 parts deionized water stirred evenly in a high-speed stirrer; solution h is composed of 25 parts silane coupling agent, 25 parts diethanolamine, 120 parts nano silica, and 400 parts deionized water. The dropwise addition time is 4 h, and stirring is continued for 2 h after the dropwise addition is completed to obtain milky white antipermeability component E.

[0093] The preparation method of the above-mentioned admixture for high self-compacting concrete of rockfill dams is the same as that in Example 1.

[0094] Example 3

[0095] An admixture for high self-compacting concrete for rockfill dams is composed of the following raw materials in parts by weight: 580 parts of dispersing component A, 80 parts of water-retaining and self-curing component B, 120 parts of reinforcing component C, 45 parts of shrinkage-reducing component D, 125 parts of impermeable component E, and 50 parts of deionized water.

[0096] The preparation method of dispersion component A is as follows: 360 parts of hydroxybutyl vinyl polyethylene glycol ether (VPEG3000) and 300 parts of deionized water are added to a reactor equipped with a stirrer, a dropping device, and a heating device. The reactor temperature is set to 10℃ and the rotation speed is set to 300 r / min. Then, an initiator composed of 5 parts of hydrogen peroxide and 2 parts of ferrous sulfate solution (concentration of 1 wt.%) is added. Subsequently, solutions a and b are added dropwise (solution a consists of 30 parts of acrylic acid, 15 parts of maleic anhydride, 3 parts of vinyl methacrylate, 5 parts of hydroxyethyl acrylate, 8 parts of hydroxypropyl acrylate, and 100 parts of deionized water; solution b consists of 1.5 parts of sodium formaldehyde sulfoxylate (E51), 2 parts of mercaptopropionic acid, and 120 parts of deionized water). The dropwise addition time is 1 h. After the dropwise addition is completed, the reaction continues for 90 min. After the reaction is completed, the temperature of the system is lowered to room temperature, and the system concentration is adjusted to 40 wt.% with deionized water to obtain dispersion component A. The weight-average molecular weight M of dispersion component A is determined by gel permeation chromatography. wThe concentration was 32765 g / mol, with a conversion rate of 97%.

[0097] The preparation method of water-retaining self-maintaining component B is as follows: Add 500 parts deionized water, 20 parts sodium dodecyl sulfate, 10 parts sodium lauryl ether sulfate, 5 parts sodium tetradecyl sulfate, and 50 parts EFS4070 (purchased from Shanghai Zhongcheng Fine Chemical Co., Ltd.) to a reactor equipped with a stirrer, a dropping device, a reflux device, and a heating device. After stirring evenly, raise the temperature to 80℃, set the rotation speed to 220 r / min, and begin dropping in solution c and solution d (solution c consists of 100 parts ethyl methacrylate, 60 parts butyl acrylate, 3... The reaction mixture consists of 0 parts methacrylic acid, 25 parts styrene, and 10 parts ethylene glycol ethyl ether; solution d consists of 5 parts ammonium persulfate and 120 parts deionized water. The addition time is 2 hours, and the mixture is kept warm for 1 hour after the addition is completed. Then, the temperature of the reaction system is lowered to room temperature, and 30 parts ammonia water (concentration of 0.1 mol / L) is added. After stirring evenly, the curing component B1 is obtained. 800 parts of the above curing component B1 and 2 parts xanthan gum are mixed and stirred at 500 r / min for 30 minutes to obtain water-retaining self-curing component B.

[0098] The preparation method of reinforcing component C is as follows: 140 parts of calcium nitrate tetrahydrate and 400 parts of deionized water are added to a reactor equipped with a high-speed stirrer, a dropping device and a heating device. The reactor temperature is set to 60℃ and the rotation speed is set to 5000 r / min. Solution e and solution f (solution e consists of 1 part xanthan gum, 2 parts diethanolamine, 2 parts citric acid and 500 parts deionized water; solution f is prepared by stirring 20 parts sodium carbonate and 200 parts deionized water at a speed of 5000 r / min for 30 min) are added dropwise over 3 h. After the addition is completed, stirring is continued for 2 h to obtain milky white reinforcing component C.

[0099] Shrinkage reduction component D consists of 20 parts nanocellulose (purchased from Wuhan Huaxiang Kejie Biotechnology Co., Ltd.), 3 parts triterpenoid saponin air-entraining agent solution (concentration of 40 wt.%), 0.5 parts polyether defoamer, 0.5 parts organosilicon defoamer and 100 parts deionized water;

[0100] The preparation method of antipermeability component E is as follows: 50 parts of stearic acid and 50 parts of oleic acid are added to a reactor equipped with a high-speed stirrer, a dropping device, and a heating device. The reactor temperature is set to 70℃, the stirring speed is set to 280 r / min, and after stirring for 30 min to fully dissolve, the temperature is kept constant, the stirring speed is changed to 1500 r / min, and 100 parts of NaOH solution (concentration of 30 wt.%) are added dropwise to the reactor. After 2 h of dropwise addition, an emulsion liquid is obtained. After the emulsion liquid cools to room temperature, solution g and solution h are added dropwise simultaneously at a stirring speed of 1500 r / min. Solution g is composed of 1 part xanthan gum and 500 parts deionized water stirred evenly in a high-speed stirrer; solution h is composed of 20 parts silane coupling agent, 20 parts diethanolamine, 100 parts nano silica, and 400 parts deionized water. The dropwise addition time is 3 h, and after the dropwise addition is completed, stirring is continued for 2 h to obtain milky white antipermeability component E.

[0101] The preparation method of the above-mentioned admixture for high self-compacting concrete of rockfill dams is the same as that in Example 1.

[0102] Example 4

[0103] An admixture for high self-compacting concrete for rockfill dams is composed of the following raw materials in parts by weight: 580 parts of dispersing component A, 80 parts of water-retaining and self-curing component B, 120 parts of reinforcing component C, 45 parts of shrinkage-reducing component D, 125 parts of impermeable component E, and 50 parts of deionized water.

[0104] The preparation method of dispersion component A is as follows: 360 parts of hydroxybutyl vinyl polyethylene glycol ether (VPEG3000) and 300 parts of deionized water are added to a reactor equipped with a stirrer, a dropping device, and a heating device. The reactor temperature is set to 10℃ and the rotation speed is set to 300 r / min. Then, an initiator composed of 5 parts of hydrogen peroxide and 2 parts of ferrous sulfate solution (concentration of 1 wt.%) is added. Subsequently, solutions a and b are added dropwise (solution a consists of 30 parts of acrylic acid, 15 parts of maleic anhydride, 3 parts of vinyl methacrylate, 5 parts of hydroxyethyl acrylate, 8 parts of hydroxypropyl acrylate, and 100 parts of deionized water; solution b consists of 1.5 parts of sodium formaldehyde sulfoxylate (E51), 2 parts of mercaptopropionic acid, and 120 parts of deionized water). The dropwise addition time is 2 h. After the dropwise addition is completed, the reaction continues for 90 min. After the reaction is completed, the temperature of the system is lowered to room temperature, and the system concentration is adjusted to 40 wt.% with deionized water to obtain dispersion component A. The weight-average molecular weight M of dispersion component A is determined by gel permeation chromatography. w The concentration was 32765 g / mol, with a conversion rate of 97%.

[0105] The preparation method of water-retaining self-maintaining component B is as follows: Add 550 parts deionized water, 25 parts sodium dodecyl sulfate, 15 parts sodium lauryl ether sulfate, 7 parts sodium tetradecyl sulfate, and 55 parts EFS4070 (purchased from Shanghai Zhongcheng Fine Chemical Co., Ltd.) to a reactor equipped with a stirrer, a dropping device, a reflux device, and a heating device. After stirring evenly, raise the temperature to 85℃, set the rotation speed to 240 r / min, and begin dropping in solution c and solution d (solution c consists of 120 parts ethyl methacrylate, 70 parts butyl acrylate, and 4...). The reaction mixture consists of 0 parts methacrylic acid, 30 parts styrene, and 12 parts ethylene glycol ethyl ether; solution d consists of 6 parts ammonium persulfate and 120 parts deionized water. The addition time is 3 hours, and the mixture is kept warm for 1 hour after the addition is completed. Then, the temperature of the reaction system is lowered to room temperature, and 30 parts ammonia water (concentration of 0.1 mol / L) is added. After stirring evenly, the curing component B1 is obtained. 800 parts of the above curing component B1 and 3 parts xanthan gum are mixed and stirred at 500 r / min for 30 minutes to obtain water-retaining self-curing component B.

[0106] The preparation method of reinforcing component C is as follows: 160 parts of calcium nitrate tetrahydrate and 450 parts of deionized water are added to a reactor equipped with a high-speed stirrer, a dropping device, and a heating device. The reactor temperature is set to 65℃ and the rotation speed is set to 8000 r / min. Solution e and solution f (solution e consists of 1 part xanthan gum, 3 parts diethanolamine, 3 parts citric acid, and 500 parts deionized water; solution f is prepared by stirring 25 parts sodium carbonate and 200 parts deionized water at a speed of 5000 r / min for 30 min) are added dropwise over a period of 3 h. After the addition is completed, stirring is continued for 2 h to obtain milky white reinforcing component C.

[0107] Shrinkage reduction component D consists of 25 parts nanocellulose (purchased from Wuhan Huaxiang Kejie Biotechnology Co., Ltd.), 4 parts triterpenoid saponin air-entraining agent solution (concentration of 40 wt.%), 0.5 parts polyether defoamer, 0.5 parts organosilicon defoamer and 100 parts deionized water;

[0108] The preparation method of antipermeability component E is as follows: 55 parts of stearic acid and 55 parts of oleic acid are added to a reactor equipped with a high-speed stirrer, a dropping device, and a heating device. The reactor temperature is set to 75℃, the stirring speed is set to 300 r / min, and after stirring for 30 min to fully dissolve, the temperature is kept constant, the stirring speed is changed to 1500 r / min, and 120 parts of NaOH solution (concentration of 30 wt.%) are added dropwise to the reactor. After 3 h of dropwise addition, an emulsion liquid is obtained. After the emulsion liquid cools to room temperature, solution g and solution h are added dropwise simultaneously at a stirring speed of 1500 r / min. Solution g is composed of 1 part xanthan gum and 500 parts deionized water stirred evenly in a high-speed stirrer; solution h is composed of 25 parts silane coupling agent, 25 parts diethanolamine, 120 parts nano silica and 400 parts deionized water. The dropwise addition time is 4 h, and after the dropwise addition is completed, stirring is continued for 2 h to obtain milky white antipermeability component E.

[0109] The preparation method of the above-mentioned admixture for high self-compacting concrete of rockfill dams is the same as that in Example 1.

[0110] Comparative Example 1

[0111] An admixture for high self-compacting concrete for rockfill dams differs from Example 3 in that the hydroxybutyl vinyl polyethylene glycol ether (VPEG3000) in dispersion component A is replaced with an equal weight proportion of vinyl diethylene glycol ether (GPEG3000) (purchased from Shanghai Dongda Chemical Co., Ltd.), otherwise it is the same as Example 3.

[0112] Comparative Example 2

[0113] An admixture for high self-compacting concrete for rockfill dams differs from Example 3 in that the water-retaining and self-curing component B is omitted, while the rest is the same as Example 3.

[0114] Comparative Example 3

[0115] An admixture for high self-compacting concrete for rockfill dams differs from Example 3 in that the nanocellulose in shrinkage component D is replaced with an equal weight proportion of hydroxyethyl methylcellulose (purchased from Shandong Yousuo Chemical Technology Co., Ltd., model LH55RR), otherwise it is the same as Example 3.

[0116] Comparative Example 4

[0117] An admixture for high self-compacting concrete for rockfill dams differs from Example 3 in that the reactor temperature is set to 50°C in the preparation method of the anti-seepage component E, while the rest is the same as in Example 3.

[0118] Comparative Example 5

[0119] An admixture for high self-compacting concrete in rockfill dams is composed of the following raw materials in parts by weight: 500 parts of dispersing component A, 50 parts of water-retaining and self-curing component B, 80 parts of reinforcing component C, 45 parts of shrinkage-reducing component D, 125 parts of impermeable component E, and 200 parts of deionized water; other components are the same as in Example 3.

[0120] The performance of the admixtures obtained in Examples 1-4 and Comparative Examples 1-5 was tested through high self-compacting concrete experiments. C was selected as the high self-compacting concrete material. 9015W8 high self-compacting concrete, mix proportions are shown in Table 1. The cement used is Esheng P·O 42.5 cement; the sand is silt-containing manufactured sand with a fineness modulus of 2.8, stone powder content of 6%, and methylene blue MB value of 1.0; the aggregate is 5~20mm continuously graded crushed stone. The water-reducing agent formula for one ton of concrete in the blank group is: polycarboxylate superplasticizer (C6 type): slump-retaining superplasticizer (C8 type): retarder (sodium gluconate): air-entraining agent (triterpenoid saponins): water = 300:100:20:1:579. The water-reducing agent formula for one ton of concrete in the examples and comparative groups is: polycarboxylate superplasticizer (C6 type): slump-retaining superplasticizer (C8 type): admixture: retarder (sodium gluconate): air-entraining agent (triterpenoid saponins): water = 150:50:200:20:1:579. 90 The slump, spread, V-shaped funnel, and time-dependent loss of slump spread of 15W8 high self-compacting concrete were tested with reference to DL / T 5806-2020 "Specification for Construction of Rockfill Concrete in Hydropower and Water Conservancy Projects"; C 90 The T500 test for 15W8 high self-compacting concrete refers to JGJ / T 283-2012 "Technical Specification for Application of Self-Compacting Concrete"; C 90 The preparation, molding, curing, air content, compressive strength, shrinkage rate and permeability coefficient of 15W8 high self-compacting concrete specimens were tested in accordance with DLT 5150-2017 "Test Procedure for Hydraulic Concrete". The test results are shown in Table 2.

[0121] Table 1 C 90 15W8 High Self-Compacting Concrete Mix Proportion (kg / m³) 3 )

[0122]

[0123] Table 2 C 90 Test results of 15W8 high self-compacting concrete

[0124]

[0125] Table 2 shows that, compared to the control group, the high self-compacting concrete prepared using the admixtures in Examples 1-4 of this invention exhibits smaller slump, spread, and air content loss after 1 hour; shorter T500 and V-shaped funnel times; smaller time increase after 1 hour; smaller shrinkage rate and permeability coefficient at 7 and 28 days; and higher compressive strength at 7 and 28 days. Compared to Comparative Examples 1-5, the high self-compacting concrete prepared using the admixtures in Examples 1-4 of this invention exhibits smaller slump, spread, and air content loss after 1 hour; shorter T500 and V-shaped funnel times; smaller time increase after 1 hour; smaller shrinkage rate and permeability coefficient at 7 and 28 days; and higher compressive strength at 7 and 28 days. These findings demonstrate that the admixtures provided by this invention can significantly improve the early and later strength of high self-compacting concrete while reducing its shrinkage and impermeability.

[0126] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. An admixture for high self-compacting concrete in rockfill dams, characterized in that, The raw materials include the following parts by weight: dispersion component A 550~600 parts, water-retaining and self-curing component B 60~100 parts, reinforcing component C 100~140 parts, shrinkage-reducing component D 30~60 parts, impermeability-resistant component E 100~150 parts, and water 0~110 parts; The dispersion component A is polymerized from macromonomers and small monomers, wherein the macromonomer is hydroxybutyl vinyl polyethylene glycol ether, and the small monomers are maleic anhydride, vinyl methacrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate; the water-retaining and self-maintaining component B is composed of xanthan gum and maintenance component B1; the reinforcing component C is a mixture containing nano-calcium carbonate; the shrinkage-reducing component D is a mixture containing nano-cellulose; and the impermeability-resistant component E is a mixture containing fatty acid salts and nano-silica. The preparation method of the water-retaining self-maintaining component B includes the following steps: water, sodium dodecyl sulfate, sodium lauryl ether sulfate, sodium tetradecyl sulfate and surfactant are mixed evenly and heated, then solution c and solution d are added dropwise, the temperature is maintained after the dropwise addition is completed, the reaction system is cooled to room temperature, and then ammonia water is added to obtain maintenance component B1; the maintenance component B1 and xanthan gum are stirred and mixed evenly to obtain the water-retaining self-maintaining component B; By weight, solution c consists of 80-120 parts ethyl methacrylate, 50-70 parts butyl acrylate, 20-40 parts methacrylic acid, 20-30 parts styrene, and 8-12 parts ethylene glycol ethyl ether; solution d consists of 4-6 parts ammonium persulfate and 120 parts water. The weight ratio of water, sodium dodecyl sulfate, sodium lauryl ether sulfate, sodium tetradecyl sulfate and surfactant is (450~550):(15~25):(5~15):(3~7):(45~55); the weight ratio of maintenance component B1 and xanthan gum is 800:(1~3).

2. The admixture for high self-compacting concrete in rockfill dams according to claim 1, characterized in that, The preparation method of the dispersion component A includes the following steps: adding an initiator to a mixed solution of hydroxybutyl vinyl polyethylene glycol ether and water to carry out a polymerization reaction, then adding solution a and solution b dropwise, continuing the reaction after the dropwise addition is completed, then cooling the reaction system to room temperature, and then adjusting the system concentration with water to obtain the dispersion component A; The weight ratio of the hydroxybutyl vinyl polyethylene glycol ether to water is (320~400):(250~350); By weight, the initiator consists of 4-6 parts hydrogen peroxide and 1-3 parts ferrous sulfate solution; solution a consists of 30 parts acrylic acid, 10-20 parts maleic anhydride, 2-4 parts vinyl methacrylate, 4-6 parts hydroxyethyl acrylate, 6-10 parts hydroxypropyl acrylate, and 100 parts water; solution b consists of 1.5 parts sodium formaldehyde sulfoxylate, 2 parts mercaptopropionic acid, and 120 parts water. The polymerization reaction temperature is 8~12℃; the dropwise addition time of liquid a and liquid b is 1~3h; and the reaction time after the dropwise addition is 60~120min.

3. The admixture for high self-compacting concrete in rockfill dams according to claim 2, characterized in that, The weight-average molecular weight M of the dispersion component A w The value is 30,000~34,000 g / mol.

4. The admixture for high self-compacting concrete in rockfill dams according to claim 1, characterized in that, The temperature is raised to 75~85℃; the dripping time of solution c and solution d is 1~3h; the holding time after dripping is completed is 1h.

5. The admixture for high self-compacting concrete in rockfill dams according to claim 1, characterized in that, The preparation method of the reinforcing component C includes the following steps: under the conditions of a temperature of 55~65℃ and a rotation speed of 3000~8000r / min, solution e and solution f are added dropwise to a mixed solution of calcium nitrate tetrahydrate and water, and stirring is continued after the addition is completed to obtain the reinforcing component C; The weight ratio of the tetrahydrate calcium nitrate to water is (120~160):(350~450). By weight, solution e consists of 1 part xanthan gum, 1-3 parts diethanolamine, 1-3 parts citric acid, and 500 parts water; solution f consists of 15-25 parts sodium carbonate and 200 parts water. The addition time for liquids e and f is 3 hours; the stirring time after the addition is completed is 2 hours.

6. The admixture for high self-compacting concrete in rockfill dams according to claim 1, characterized in that, By weight, the shrinkage-reducing component D consists of 15-25 parts nanocellulose, 2-4 parts triterpenoid saponin solution, 0.5 parts polyether defoamer, 0.5 parts organosilicon defoamer and 100 parts water.

7. The admixture for high self-compacting concrete in rockfill dams according to claim 1, characterized in that, The preparation method of the antipermeability component E includes the following steps: under the conditions of a temperature of 65~75℃ and a rotation speed of 260~300r / min, a mixture of stearic acid and oleic acid is stirred and dissolved. While keeping the temperature constant, the rotation speed is changed to 1500r / min, and NaOH solution is added dropwise. After the addition is completed, the system is cooled to room temperature, and g solution and h solution are added dropwise at a rotation speed of 1500r / min. After the addition is completed, stirring is continued to obtain the antipermeability component E. The weight ratio of stearic acid, oleic acid and NaOH solution is (45~55):(45~55):(80~120). By weight, the g solution consists of 1 part xanthan gum and 500 parts water; the h solution consists of 15-25 parts silane coupling agent, 15-25 parts diethanolamine, 80-120 parts nano silica and 400 parts water. The NaOH solution is added dropwise over a period of 1 to 3 hours; the g solution and h solution are added dropwise over a period of 2 to 4 hours; and stirring continues for 2 hours after the addition is completed.

8. A method for preparing an admixture for high self-compacting concrete for rockfill dams as described in any one of claims 1 to 7, characterized in that, include: The dispersing component A, the water-retaining and self-curing component B, the reinforcing component C, the shrinkage-reducing component D, the impermeable component E, and water are mixed evenly to obtain the admixture for high self-compacting concrete used in rockfill dams.

9. The application of an admixture as described in any one of claims 1 to 7 for high self-compacting performance concrete for rockfill dams in the preparation of high self-compacting performance concrete for rockfill dams.

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