Composite drag-reducing and viscosity-reducing concrete for high-lift pumping

Abstract

This application relates to the field of pumped concrete, specifically disclosing a composite drag-reducing and viscosity-reducing concrete for high-lift pumping, comprising the following raw materials in parts by weight: 400 parts cement; 1090-1276 parts crushed stone; 762-892 parts manufactured sand; 60-80 parts fly ash; 30-50 parts vitrified microspheres; 150-177 parts mixing water; 7-9 parts polycarboxylate superplasticizer; 0.1-0.3 parts air-entraining agent; and 16-24 parts viscosity-reducing filler. The viscosity-reducing filler comprises a support, sodium citrate, and nut shell fragments, wherein the weight ratio of the support to sodium citrate is (6-9):(1-2):1. This application has the effect of improving the compaction of pumped concrete.

Description

Technical Field

[0001] This application relates to the field of pumped concrete, and more particularly to a composite drag-reducing and viscosity-reducing concrete for high-lift pumping. Background Technology

[0002] Pumped concrete is a process of transporting and pouring concrete mixtures using concrete pumps or pump trucks along delivery pipelines. Depending on the pumping height and length, pumped concrete is classified into ordinary pumped concrete and high-lift pumped concrete. High-lift pumped concrete is generally used for pier construction when the height exceeds 100 meters.

[0003] In the construction of high-lift structures with a vertical height exceeding 120m, the output pressure of the concrete pump needs to be above 20MPa. At this pressure, the raw materials in the concrete are prone to segregation. Related technologies involve adding water-reducing agents to the concrete to reduce the amount of mixing water, thereby lowering the probability of concrete segregation. However, with the reduction in water usage, the concrete viscosity increases, and after pumping and pouring, the compaction of the concrete decreases, easily leading to problems such as honeycomb and pitted surfaces. Summary of the Invention

[0004] To improve the compaction of pumped concrete, this application provides a composite drag-reducing and viscosity-reducing concrete for high-lift pumping.

[0005] This application provides a composite drag-reducing and viscosity-reducing concrete for high-lift pumping, which adopts the following technical solution:

[0006] A composite drag-reducing and viscosity-reducing concrete for high-lift pumping comprises the following raw materials in parts by weight: 400 parts cement; 1090-1276 parts crushed stone; 762-892 parts manufactured sand; 60-80 parts fly ash; 30-50 parts vitrified microspheres; 150-177 parts mixing water; 7-9 parts polycarboxylate superplasticizer; 0.1-0.3 parts air-entraining agent; and 16-24 parts viscosity-reducing filler. The viscosity-reducing filler comprises a support, sodium citrate, and nut shell fragments, wherein the weight ratio of the support to sodium citrate is (6-9):(1-2):1.

[0007] By employing the above technical solution, vitrified microspheres, air-entraining agents, cement, polycarboxylate water-reducing agents, and viscosity-reducing fillers are used in combination. During the preparation process, hydrophobic carboxylic acid molecules disperse cement particles. At this time, the air-entraining agent increases the gas content in the concrete, further reducing the agglomeration of cement particles. The viscosity-reducing filler, under the action of sodium citrate, adsorbs onto the cement particles, reducing the probability of cement particles adhering to the conveying pipe wall, thereby reducing the pumping resistance of concrete and lowering its viscosity. During pumping, the vitrified microspheres contact the pipe wall of the conveying pipeline, reducing the pumping resistance of concrete through the ball effect. During concrete curing, water molecules penetrate into the concrete, and some sodium citrate dissolves. Under the action of vibration, the sodium citrate solution carries nut shell fragments towards the pores of the concrete and fills the pores, improving the self-compacting properties of the concrete.

[0008] Optionally, the support comprises lead citrate and raw rubber powder, wherein the weight ratio of lead citrate to raw rubber powder is 5:(2-6).

[0009] By adopting the above technical solution, during concrete preparation and pumping, sodium citrate acts as a binder adsorbed onto cement particles, and nut shells increase the porosity of the concrete, thus improving its air content. The lipids in the nut shells partially encapsulate the sodium citrate and cement particles, reducing the viscosity and resistance of the cement particles. Some sodium citrate reacts with water to form a sodium citrate solution, where lead citrate dissolves. Lead ions form an impermeable film on the surface of the cement particles, reducing their viscosity and movement resistance, facilitating concrete pumping. During concrete curing, cement hydration forms CSH gel. The sodium citrate adsorbed on the cement particles reacts with water molecules to form a sodium citrate solution, where some lead citrate dissolves. This disrupts the impermeable film, reducing its obstruction to cement hydration and increasing the lead ion content in the concrete. The CSH gel in the concrete forms Ca-Pb ettringite through physical adsorption and chemical replacement. Calcium and silicon elements in the CSH gel are fixed through chemical bonding, improving the self-compacting properties of the CSH gel and increasing the compaction density of the concrete. At the same time, as lead citrate dissolves, the number of hydroxyl groups produced by hydrolysis increases, which in turn increases the consumption of hydrogen ions, further promoting the dissolution of sodium citrate, and thus promoting the dissolution of lead citrate, resulting in a sustained release of lead ions, thereby continuously increasing the self-compacting properties of concrete.

[0010] Lipids and pectin on the surface of nut shells separate from cellulose under the action of alkaline solution, forming a viscous liquid. This facilitates the fixation of the solution formed by sodium citrate and lead citrate in the pores of concrete. The cellulose and lignin in the nut shells fix the solution, reducing the loss of lead ions.

[0011] Optionally, the preparation of the support includes the following steps: mixing lead citrate and raw rubber powder, heating to 130-140℃, stirring evenly, cooling, crushing and rounding to obtain particles, which are the support.

[0012] By adopting the above technical solution, the raw rubber powder fixes the lead citrate, reducing the consumption of lead citrate during the concrete preparation process; after the concrete is cured, the raw rubber powder, as an elastic material, improves the toughness of the concrete, thereby improving the compressive strength of the concrete.

[0013] Optionally, the preparation of the support includes the following steps: mixing lead citrate with raw rubber powder, heating to 130-140℃, stirring evenly, cooling and then crushing and rounding to obtain particles; mixing the particles with crushed stones and stirring, then separating to obtain a support with pits on the surface.

[0014] By adopting the above technical solution, the impact of crushed stone particles forms pits on the particle surface, which facilitates the support to load sodium citrate and visible debris.

[0015] Optionally, the preparation of the viscosity-reducing filler includes the following steps: dispersing sodium citrate and nut shell fragments in ethanol, stirring at 35-45℃ for 10-20 min at a stirring speed of 15-20 r / s to obtain a suspension; placing the support in the suspension, heating in a constant temperature water bath and magnetically stirring at a temperature of 35-45℃ and a stirring speed of 15-20 r / s for 5-6 h; and drying the reactants after cooling to obtain the viscosity-reducing filler.

[0016] By adopting the above technical solution, ethanol disperses sodium citrate on the one hand, and pectin in nut fragments on the other hand, under the action of pectin, sodium citrate adheres to the surface of the support, thereby improving the bonding strength between sodium citrate and the support.

[0017] Optionally, sodium dodecylbenzenesulfonate solution can be added dropwise during magnetic stirring at a rate of 4-6 drops / h.

[0018] By adopting the above technical solution, sodium dodecylbenzenesulfonate solution, as a surfactant, works in conjunction with sodium citrate to reduce the agglomeration of sodium citrate. Sodium citrate forms a uniform film on the surface of the support, thereby improving the uniformity of the structure and performance of the viscosity-reducing filler.

[0019] Optionally, after drying, the filler can be kept at 30-40℃ for two hours to obtain a viscosity-reducing filler.

[0020] By adopting the above technical solution, the bonding strength of the support, sodium citrate and nut fragments was improved.

[0021] Optionally, the nut shells are selected from pumpkin seed shells.

[0022] By adopting the above technical solution, pumpkin seed shells are combined with lead citrate. The pectin in the pumpkin seed shells adsorbs and binds lead ions, which reduces the consumption of lead citrate during concrete preparation, improves the utilization rate of lead citrate, and enhances the self-compacting properties of concrete.

[0023] Optionally, the vitrified microspheres are selected from solid vitrified microspheres with a particle size of less than 40 μm.

[0024] By adopting the above technical solution, the particle size is less than 40μm, which facilitates the effect of the rolling ball and reduces the viscosity and resistance of the concrete; the solid structure makes it difficult for the vitrified microspheres to separate from the crushed stone, cement and other materials in the concrete under inertia, thus improving the stability of the concrete.

[0025] In summary, this application includes at least one of the following beneficial technical effects:

[0026] 1. A combination of cement, vitrified microspheres, air-entraining agent, and viscosity-reducing filler is used. The viscosity-reducing filler is a support structure with sodium citrate and pumpkin seed shell fragments adhering to its surface. The support structure is formed by mixing lead citrate and raw rubber powder. During concrete preparation and pumping, the hydrophobic carboxylic acid molecules disperse the cement particles. At this time, the air-entraining agent increases the gas content in the concrete. The viscosity-reducing filler is adsorbed on the surface of the cement particles, and the pumpkin seed shell fragments act as a support, increasing the porosity of the concrete and further increasing the gas content. This reduces the agglomeration of cement particles and decreases the probability of cement particles adhering to the conveying pipe wall, thereby reducing the pumping resistance of concrete. The lipids contained in the pumpkin seed shell fragments partially coat the sodium citrate and cement particles, reducing the viscosity and resistance of the cement particles. During concrete curing, water molecules penetrate the concrete, causing cement hydration and the formation of CSH gel. Some sodium citrate reacts with water to form a sodium citrate solution, where lead citrate dissolves. Lead ions form an impermeable film on the surface of cement particles. This film, combined with vitrified microspheres, reduces the viscosity and movement resistance of the cement particles, facilitating concrete pumping. During curing, water molecules penetrate the concrete, causing cement hydration and the formation of CSH gel. Some sodium citrate dissolves, and some lead citrate dissolves in the sodium citrate solution. The impermeable film is destroyed, reducing its obstruction to cement hydration and increasing the lead ion content in the concrete. The CSH gel in the concrete forms Ca-Pb ettringite through physical adsorption and chemical replacement. Calcium and silicon elements in the CSH gel are fixed through chemical bonding, improving the self-compacting properties of the CSH gel and increasing the compaction density of the concrete.

[0027] 2. The lipids and pectin on the surface of pumpkin seed shells separate from cellulose under the action of alkaline solution, forming a viscous liquid. This facilitates the fixation of the solution formed by sodium citrate and lead citrate in the pores of concrete. The cellulose and lignin in the nut shells fix the solution, reducing the loss of lead ions.

[0028] 3. The surface of the support has pits and depressions, which facilitates the adhesion of sodium citrate and the slow release of sodium citrate. The viscosity-reducing filler changes from a solid phase to a mobile phase and then back to a solid phase during concrete curing, which facilitates filling the pores of the concrete and thus improves the compaction of the concrete.

[0029] 4. Sodium dodecylbenzenesulfonate solution, as a surfactant, works in conjunction with sodium citrate to reduce the aggregation of sodium citrate. Sodium citrate forms a uniform film on the support surface, improving the uniformity of the structure and performance of the viscosity-reducing filler. Detailed Implementation

[0030] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0031] Unless otherwise specified, the following examples shall be conducted under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all raw materials used in the following examples shall be commercially available.

[0032] The cement is PO42.5 grade cement with a specific surface area of ​​332 m². 2 / kg, initial setting time 140min, final setting time 205min; fineness modulus of manufactured sand 3.0, apparent density 2.69g / cm³ 2 Stone powder content ≤7.0%, MB value <1.40g / kg; apparent density of crushed stone 2.7g / cm2, bulk density 1.48g / cm2. 2 The parent rock has a strength ≥90MPa and a crushing value of 9.0%; the fly ash fineness (45μm square mesh sieve) is 12.8%; the vitrified microspheres are selected from closed-cell perlite solid glass microspheres with a density of 150kg / m³. 3 The particle size is 30μm; the solid content of the polycarboxylate superplasticizer is 23.5%, and the water reduction rate is 30%; the air-entraining agent is selected from ATS-71 concrete air-entraining agent, pH 8.5; lead citrate, lead content 62.17%; raw rubber powder, raw material natural rubber, fineness 40 mesh.

[0033] Sodium citrate

[0034] Preparation Example

[0035] Preparation Example 1

[0036] S1. Mix 8 kg of lead citrate with 4 kg of raw rubber powder, heat to 130°C, stir evenly, cool, crush and round to obtain particles with a particle size of 5 mm; mix the particles with crushed stones and stir, then separate and screen to obtain a support with pits on the surface.

[0037] S2. Crush the pumpkin seed shells and grind them to obtain pumpkin seed shell powder. Disperse 2 kg of sodium citrate and 2 kg of pumpkin seed shell powder in ethanol and stir at 40°C for 10 min at a stirring speed of 15 r / s to obtain a suspension.

[0038] S3. Take 12 kg of the support prepared in S1 and put it into the suspension prepared in S2. The support should be completely immersed in the suspension. Heat in a constant temperature water bath and stir magnetically at 40℃ and 15 r / s. During the reaction, add sodium dodecylbenzenesulfonate solution with a concentration of 0.5 mol / L at a dropping rate of 5 drops / h for 5.5 h. S4. After cooling, place the reactants in an oven to dry at 35℃ for two hours. Shake to obtain the viscosity-reducing filler.

[0039] Preparation Example 2

[0040] S1. Mix 8 kg of lead citrate with 6 kg of raw rubber powder, heat to 130°C, stir evenly, cool, crush and round to obtain particles with a particle size of 5 mm; mix the particles with crushed stones and stir, then separate to obtain a support with pits on the surface.

[0041] S2. Crush the pumpkin seed shells and grind them to obtain pumpkin seed shell powder. Disperse 3 kg of sodium citrate and 2 kg of pumpkin seed shell powder in ethanol and stir at 40°C for 10 min at a stirring speed of 15 / s to obtain a suspension.

[0042] S3. Take 15 kg of the support prepared in S1 and put it into the suspension prepared in S2. The support should be completely immersed in the suspension. Heat in a constant temperature water bath and stir magnetically. The temperature is 40℃ and the stirring speed is 15 r / s. During the reaction, add sodium dodecylbenzenesulfonate solution with a concentration of 0.5 mol / L at a dropping rate of 5 drops / h. The treatment time is 5.5h.

[0043] S4. After cooling, place the reactants in an oven to dry at 35°C for two hours, and then shake to obtain the viscosity-reducing filler.

[0044] Preparation Example 3

[0045] S1. Mix 8 kg of lead citrate with 10 kg of raw rubber powder, heat to 130°C, stir evenly, cool, crush and round to obtain particles with a particle size of 5 mm; mix the particles with crushed stones and stir, then separate to obtain a support with pits on the surface.

[0046] S2. Crush the pumpkin seed shells and grind them to obtain pumpkin seed shell powder. Disperse 4 kg of sodium citrate and 2 kg of pumpkin seed shell powder in ethanol and stir at 40°C for 10 min at a stirring speed of 15 r / s to obtain a suspension.

[0047] S3. Take 18 kg of the support prepared in S1 and put it into the suspension prepared in S2. The support should be completely immersed in the suspension. Heat in a constant temperature water bath and stir magnetically. The temperature is 40℃ and the stirring speed is 15 r / s. During the reaction, add sodium dodecylbenzenesulfonate solution dropwise. The concentration of sodium dodecylbenzenesulfonate solution is 0.5 mol / L and the dropping rate is 5 drops / h. The treatment time is 5.5h.

[0048] S4. After cooling, place the reactants in an oven to dry at 35°C for two hours, and then shake to obtain the viscosity-reducing filler.

[0049] Preparation Examples 4-9

[0050] The difference from Preparation Example 2 is that the amount and type of each substance added are different, as detailed in Table 1.

[0051] Preparation Example 10

[0052] S1. Crush and grind the pumpkin seed shells to obtain pumpkin seed shell powder. Disperse 3 kg of sodium citrate and 2 kg of pumpkin seed shell powder in ethanol and stir at 40°C for 10 min at a stirring speed of 15 / s to obtain a suspension.

[0053] S2. Place 15 kg of lead citrate into the suspension prepared in S2, ensuring that the support is completely submerged in the suspension. Heat in a constant temperature water bath with magnetic stirring at 40°C and a stirring speed of 15 r / s. During the reaction, add sodium dodecylbenzenesulfonate solution with a concentration of 0.5 mol / L at a dropping rate of 5 drops / h. The treatment time is 5.5 h.

[0054] S3. After cooling, place the reactants in an oven to dry at 40°C for two hours, and then shake to obtain the viscosity-reducing filler.

[0055] Preparation Example 11

[0056] S1. Crush and grind the pumpkin seed shells to obtain pumpkin seed shell powder. Disperse 3 kg of sodium citrate and 2 kg of pumpkin seed shell powder in ethanol and stir at 40°C for 10 min at a stirring speed of 15 / s to obtain a suspension.

[0057] S2. Place 15 kg of raw rubber powder into the suspension prepared in S2, ensuring that the support is completely submerged in the suspension. Heat in a constant temperature water bath with magnetic stirring at 40°C and a stirring speed of 15 r / s. During the reaction, add sodium dodecylbenzenesulfonate solution with a concentration of 0.5 mol / L at a dropping rate of 5 drops / h. The treatment time is 5.5 h.

[0058] S3. After cooling, place the reactants in an oven to dry at 40°C for two hours, and then shake to obtain the viscosity-reducing filler.

[0059] Preparation Example 12

[0060] The difference from Preparation Example 2 is that sodium citrate was not added.

[0061] Preparation Example 13

[0062] The difference from Preparation Example 2 is that no pumpkin seed shell fragments were added.

[0063] Preparation Example 14

[0064] The difference from Preparation Example 2 is that: S1, 8 kg of lead citrate and 6 kg of raw rubber powder are mixed, heated to 130°C, stirred evenly, cooled, crushed and rounded to obtain particles with a particle size of 5 mm, which are the support.

[0065] Preparation Example 15

[0066] The difference from Preparation Example 2 is that sodium dodecylbenzenesulfonate solution was not added.

[0067] Preparation Example 16

[0068] The difference from Preparation Example 2 is that in S4, no heat preservation was performed after drying.

[0069] Table 1. Raw material list (kg) for preparation examples 1-13

[0070]

[0071]

[0072] Table 2. Process tables for Preparation Example 2 and Preparation Examples 14-16

[0073] support Sodium dodecylbenzenesulfonate solution After the granules are dried Preparation Example 2 pitted Add drop by drop Insulation Preparation Example 14 No pits Add drop by drop Insulation Preparation Example 15 pitted Undropped Insulation Preparation Example 16 pitted Add drop by drop Not insulated

[0074] Example

[0075] Example 1

[0076] S1. Mix 40kg cement, 6kg fly ash, 3kg vitrified microspheres, 15kg mixing water, 0.7kg polycarboxylate superplasticizer and 0.03kg air-entraining agent and stir evenly to obtain slurry;

[0077] S2. Add 1.6 kg of the viscosity-reducing filler prepared in Preparation Example 1 to the slurry and stir evenly to obtain the modified slurry;

[0078] S3. Add 109 kg of crushed stone and 76.2 kg of manufactured sand to the modified slurry, stir and mix evenly to obtain concrete that meets the requirements for drag reduction and viscosity reduction.

[0079] Example 2

[0080] S1. Mix 40kg of cement, 7kg of fly ash, 4kg of vitrified microspheres, 16.4kg of mixing water, 0.8kg of polycarboxylate superplasticizer and 0.02kg of air-entraining agent and stir evenly to obtain slurry;

[0081] S2. Add 2 kg of the viscosity-reducing filler prepared in Preparation Example 2 to the slurry and stir evenly to obtain the modified slurry;

[0082] S3. Add 118.5 kg of crushed stone and 82.7 kg of manufactured sand to the modified slurry, stir and mix evenly to obtain concrete that meets the requirements for drag reduction and viscosity reduction.

[0083] Example 3

[0084] S1. Mix 40kg cement, 8kg fly ash, 5kg vitrified microspheres, 17.7kg mixing water, 0.9kg polycarboxylate superplasticizer and 0.01kg air-entraining agent and stir evenly to obtain slurry;

[0085] S2. Add 2.4 kg of the viscosity-reducing filler prepared in Preparation Example 3 to the slurry and stir evenly to obtain the modified slurry;

[0086] S3. Add 127.6 kg of crushed stone and 89.2 kg of manufactured sand to the modified slurry, stir and mix evenly to obtain concrete that meets the requirements for drag reduction and viscosity reduction.

[0087] Example 4

[0088] The difference from Example 2 is that 3 kg of vitrified microspheres were added.

[0089] Example 5

[0090] The difference from Example 2 is that 5 kg of vitrified microspheres were added.

[0091] Examples 6-11

[0092] The difference from Example 2 is that 2 kg of the viscosity-reducing filler prepared in Preparation Examples 4-9 were added sequentially.

[0093] Comparative Example

[0094] Comparative Example 1

[0095] S1. Mix 40kg of cement, 7kg of fly ash, 16.4kg of mixing water and 0.8kg of polycarboxylate superplasticizer and stir evenly to obtain slurry;

[0096] S2. Add 118.5 kg of crushed stone and 82.7 kg of manufactured sand to the slurry, stir and mix evenly to obtain concrete that meets the requirements for drag reduction and viscosity reduction.

[0097] Comparative Example 2

[0098] S1. Mix 40kg of cement, 7kg of fly ash, 4kg of vitrified microspheres, 16.4kg of mixing water, 0.8kg of polycarboxylate superplasticizer and 0.02kg of air-entraining agent and stir evenly to obtain slurry;

[0099] S2. Add 118.5 kg of crushed stone and 82.7 kg of manufactured sand to the slurry, stir and mix evenly to obtain concrete that meets the requirements for drag reduction and viscosity reduction.

[0100] Comparative Examples 3-9

[0101] The difference from Example 2 is that 2 kg of the viscosity-reducing filler prepared in Preparation Examples 10-16 were added sequentially.

[0102] Table 3. Raw material list (kg) for the examples and comparative examples.

[0103]

[0104]

[0105] Performance testing

[0106] Test methods

[0107] 1. The emptying time (s) of the V-shaped funnel in cement concrete mixture was determined using the method in T0534-2020 Test Method for V-shaped Funnel of Cement Concrete Mixture. The test results are detailed in Table 4.

[0108] 2. The plastic viscosity (Pa·s) and yield stress (Pa) of concrete were tested using an RHM-3000ICAR coaxial cylindrical rheometer. The test results are detailed in Table 4.

[0109] 3. Calculate the rate of change of plastic viscosity.

[0110] Plastic viscosity change rate (%) = (Plastic viscosity after pumping - Plastic viscosity before pumping) / Plastic viscosity before pumping × 100%

[0111] Table 4. Test results data for each embodiment and comparative example.

[0112] V Funnel emptying time / s Yield stress / Pa Plastic viscosity (Pa·s) Plastic viscosity change rate / % Example 1 8.3 187.3 69.4 6.92 Example 2 7.8 189.6 67.3 5.94 Example 3 8.4 186.5 68.7 7.57 Example 4 9.4 182.6 70.2 6.89 Example 5 8.6 187.5 66.3 8.64 Example 6 8.2 179.4 70.2 8.75 Example 7 8.1 180.6 69.8 8.33 Example 8 7.9 178.5 70.3 6.74 Example 9 8.7 179.0 69.9 7.63 Example 10 7.8 177.5 68.6 8.35 Example 11 8.6 185.6 70.3 7.12 Comparative Example 1 19.7 145.3 86.4 30.68 Comparative Example 2 14.3 155.6 82.7 24.74 Comparative Example 3 7.2 167.2 80.4 11.03 Comparative Example 4 7.4 149.6 81.3 15.24 Comparative Example 5 9.2 157.8 80.6 18.67 Comparative Example 6 8.8 169.4 81.6 12.33 Comparative Example 7 7.5 173.5 78.7 10.75 Comparative Example 8 9.1 170.6 70.6 11.33 Comparative Example 9 8.7 175.4 68.3 9.03

[0113] In conjunction with Examples 1, 2, and 3 and Table 4, by adjusting the amount and type of cement, crushed stone, manufactured sand, fly ash, vitrified microspheres, mixing water, polycarboxylate superplasticizer, air-entraining agent, and viscosity-reducing filler, the pumpability of concrete can be improved while the compaction of concrete can be enhanced.

[0114] Based on Examples 2, 1, and 2, and referring to Table 4, it can be seen that the combined use of vitrified microspheres, air-entraining agents, and viscosity-reducing fillers effectively reduced the V-funnel emptying time of concrete, increased the yield stress of concrete, and decreased the plastic viscosity and plastic viscosity change rate of concrete. The reduced V-funnel emptying time and plastic viscosity indicate improved concrete fluidity, thereby improving its pumpability. The increased yield stress reflects improved self-compactness and strength. The reduced plastic viscosity change rate indicates decreased viscosity loss during concrete pumping.

[0115] Based on Examples 2, 4, and 5, and referring to Table 4, it can be seen that with the increase of vitrified microsphere content, the plastic viscosity of concrete decreases, the yield stress of concrete first increases and then decreases, and the V-funnel emptying time of concrete first shortens and then lengthens. With the increase of vitrified microsphere content, the ball-bearing effect is significantly enhanced, while the plastic viscosity of concrete decreases. After curing, the vitrified microspheres act as a support, increasing the strength and yield stress of the concrete. However, with the continuous increase of vitrified microsphere content, the unevenness of the concrete increases, and the yield stress decreases.

[0116] The viscosity-reducing filler includes a support, sodium citrate, and nut shell fragments. Referring to Examples 2, 6, and 7, and Table 4, it can be seen that as the amount of support added increases, the plastic viscosity of the concrete first decreases and then increases; the yield stress of the concrete first increases and then decreases; and the V-funnel emptying time of the concrete first shortens and then lengthens. The support is made by mixing and curing lead citrate and raw rubber powder, then grinding it into rounds, and finally subjecting it to surface roughening treatment.

[0117] As can be seen from Example 2 and Comparative Example 3, and Table 4, the addition of raw rubber powder to the support increases the yield stress of concrete and reduces its plastic viscosity and rate of change. The raw rubber powder acts as a binder, slow-release agent, and elastic support, facilitating the role of lead citrate in the concrete curing process and improving the density and toughness of the concrete.

[0118] As can be seen from Example 2 and Comparative Example 4, and Table 4, the addition of lead citrate to the support increases the yield stress of concrete and reduces its plastic viscosity and rate of change. When combined with sodium citrate, lead citrate forms a film structure on the surface of cement particles during concrete pumping, reducing the viscosity of the concrete and improving its pumpability. During concrete curing, its combination with sodium citrate enhances the strength and self-compacting properties of the concrete.

[0119] Based on Examples 2, 8, and 9 and Table 4, it can be seen that as the weight ratio of lead citrate to raw rubber powder increases, the plastic viscosity of concrete first decreases and then increases, while the yield stress of concrete first increases and then decreases. The increased raw rubber powder content increases the fixation strength of lead citrate, making it less prone to loss during concrete preparation and pumping. However, the increased proportion of raw rubber powder reduces the release rate and efficiency of lead citrate, resulting in some lead citrate remaining unreleased and reducing its utilization rate.

[0120] As can be seen from Example 2 and Comparative Example 5, and Table 4, the addition of sodium citrate to the viscosity-reducing filler effectively reduced the V-funnel emptying time of concrete, increased the yield stress of concrete, and reduced the plastic viscosity and plastic viscosity change rate of concrete. The hydrophobic alkyl groups of sodium citrate adsorb onto the surface of cement particles, while the hydrophilic carboxyl and hydroxyl groups of sodium citrate chemically adsorb onto the Si-O bonds on the surface of cement particles, thereby adhering the support to the surface of the cement particles. This reduces the probability of cement hydration producing gel materials during concrete preparation and pumping, lowers the viscosity of concrete during pumping, and improves the pumping effect. During concrete curing, the combination of sodium citrate and lead citrate improves the mechanical properties of concrete.

[0121] As can be seen from Examples 2, 10, and 11 and Table 4, with the increase of sodium citrate content, the plastic viscosity of concrete first decreases and then increases, and the yield stress of concrete first increases and then decreases.

[0122] As can be seen from Example 2 and Comparative Example 6, and Table 4, the addition of nut shell fragments to the viscosity-reducing filler reduced the V-funnel emptying time of concrete, increased the yield stress of concrete, and reduced the plastic viscosity and plastic viscosity change rate of concrete.

[0123] The difference between Comparative Example 7 and Example 2 is that the surface of the support body was not treated with an uneven surface. As can be seen from Table 4, the concrete V-funnel prepared using the uneven surface treatment has a shorter emptying time and a higher yield stress.

[0124] The difference between Comparative Example 8 and Example 2 is that sodium dodecylbenzenesulfonate solution was not added during the preparation of the viscosity-reducing filler. According to Table 4, the addition of sodium dodecylbenzenesulfonate solution improved the uniformity of sodium citrate distribution on the support and also played a lubricating role in the concrete. Compared with the absence of sodium dodecylbenzenesulfonate solution, the emptying time of the concrete V funnel was shortened and the plastic viscosity change rate was reduced.

[0125] The difference between Comparative Example 8 and Example 2 is that no heat preservation treatment was performed after the viscosity-reducing filler was prepared. According to Table 4, the concrete V-funnel prepared in Comparative Example 8 had a longer emptying time, increased yield stress, and increased plastic viscosity change rate.

[0126] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A composite drag-reducing and viscosity-reducing concrete for high-lift pumping, characterized in that, The raw materials include the following parts by weight: 400 parts cement; 1090-1276 parts crushed stone; 762-892 parts manufactured sand; 60-80 parts fly ash; 30-50 parts vitrified microspheres; 150-177 parts mixing water; 7-9 parts polycarboxylate superplasticizer; 0.1-0.3 parts air-entraining agent; and 16-24 parts viscosity-reducing filler. The viscosity-reducing filler includes a support, sodium citrate, and nut shell fragments, wherein the weight ratio of the support to sodium citrate is (6-9):(1-2):

1. The support comprises lead citrate and raw rubber powder.

2. The composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to claim 1, characterized in that, The weight ratio of lead citrate to raw rubber powder is 4:(2-5).

3. The composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to claim 2, characterized in that, The preparation of the support includes the following steps: lead citrate and raw rubber powder are mixed, heated to 130-140℃, stirred evenly, cooled, crushed and rounded to obtain particles, which are the support.

4. The composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to claim 2, characterized in that, The preparation of the support includes the following steps: lead citrate and raw rubber powder are mixed, heated to 130-140℃, stirred evenly, cooled, crushed and rounded to obtain particles; the particles are mixed with gravel and stirred, and separated to obtain a support with pits on the surface.

5. A composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to any one of claims 2-4, characterized in that, The preparation of the viscosity-reducing filler includes the following steps: dispersing sodium citrate and nut shell fragments in ethanol, stirring at 35-45℃ for 10-20 min at a stirring speed of 15-20 r / s to obtain a suspension; placing the support in the suspension, heating in a constant temperature water bath and magnetically stirring at a temperature of 35-45℃ and a stirring speed of 15-20 r / s for 5-6 h; and drying the reactants after cooling to obtain the viscosity-reducing filler.

6. The composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to claim 5, characterized in that, Sodium dodecylbenzenesulfonate solution was added dropwise during magnetic stirring at a rate of 4-6 drops / h.

7. A composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to claim 5, characterized in that, After drying, the filler is kept at 30-40℃ for two hours to obtain the viscosity-reducing filler.

8. A composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to claim 5, characterized in that, The nut shells are selected from pumpkin seed shells.

9. A composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to claim 1, characterized in that, The vitrified microspheres are selected from solid vitrified microspheres with a particle size of less than 40 μm.

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