Composite resistance-reducing and viscosity-reducing concrete for high-lift pumping and preparation method of composite resistance-reducing and viscosity-reducing concrete

Abstract

The invention discloses composite resistance-reducing and viscosity-reducing concrete for high-lift pumping and a preparation method of the composite resistance-reducing and viscosity-reducing concrete, and relates to the technical field of concrete. The viscosity-reducing concrete is prepared from the following raw materials in parts by weight: 100 to 120 parts of cement, 50 to 70 parts of machine-made sand, 15 to 25 parts of silicon powder, 30 to 50 parts of deionized water, 2 to 5 parts of a de-foaming agent and 5 to 10 parts of a modified polycarboxylic acid water reducing agent, the preparation method comprises the following steps: reacting 9-amino-1-nonanol with decan-9-methyl methacrylate to prepare an intermediate 1, then reacting the intermediate 1 with citric acid to prepare an intermediate 2, then reacting the intermediate 2 with acryloyl chloride to prepare an intermediate 3, and finally carrying out free radical polymerization on acrylic acid, the intermediate 3 and sodium methallyl sulfonate to prepare the modified polycarboxylate superplasticizer. The viscosity-reducing concrete prepared by the invention has good compressive strength, water-reducing rate and neat paste flowability.

Description

Technical Field

[0001] The invention relates to the technical field of concrete, and in particular to a composite drag-reducing and viscosity-reducing concrete for high-lift pumping and a preparation method thereof. Background Art

[0002] As the most widely used building material in civil engineering today, concrete is made of cement as a gelling material, sand and stone as aggregates, and water mixed. Concrete not only has the advantages of abundant raw materials and low cost, but also has good plasticity, high strength and long durability, which is why it is used as the main building material. In recent years, with the rapid development of highways, high-speed railways, bridges, tunnels and urbanization construction, people's requirements for various properties of concrete are also constantly increasing. At present, adding admixtures to concrete has become the main measure to improve the performance of concrete. As the main admixture of concrete, water reducer plays a vital role in improving the working performance of concrete. It can not only greatly reduce the amount of water used in premixed concrete, but also make concrete have the advantages of large initial slump and high fluidity at low water consumption.

[0003] In recent years, a large amount of river sand resources have been gradually consumed. In order to find alternative resources, river sand used in concrete has been gradually replaced by machine-made sand. However, machine-made sand inevitably contains a certain amount of clay, which has caused an increase in the mud content of concrete, especially clay such as bentonite and kaolin, which can quickly adsorb water-reducing agent molecules to saturation adsorption in a short time, greatly destroying the actual effect of polycarboxylic acid water-reducing agent on concrete and affecting the performance of water-reducing agent used in concrete. Therefore, it is particularly important to develop a polycarboxylic acid water-reducing agent with small dosage, high water reduction rate and good net slurry fluidity.

[0004] The Chinese invention patent with publication number CN114956712A discloses a LC40 fully light pumped ceramsite concrete and a preparation method thereof. The ceramsite concrete comprises the following raw materials in parts by weight: 420-500 parts of cementitious material, 160-180 parts of mixing water, 800-840 parts of ceramic sand, 500-540 parts of ceramsite, and 1-5 parts of viscosity reducing and slump retaining agent; it has good compressive strength, but its water reduction rate and net slurry flowability are poor. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a composite drag-reducing and viscosity-reducing concrete for high-lift pumping and a preparation method thereof.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A composite drag-reducing and viscosity-reducing concrete for high-lift pumping, the viscosity-reducing concrete comprises the following raw materials in parts by weight: cement: 100-120 parts, machine-made sand: 50-70 parts, silica fume: 15-25 parts, deionized water: 30-50 parts, defoamer: 2-5 parts, modified polycarboxylic acid water-reducing agent: 5-10 parts;

[0008] The modified polycarboxylate water-reducing agent is prepared by the following method:

[0009] S1: Under nitrogen protection, methanol and 9-amino-1-nonanol were added to the reactor, stirred in an ice-water bath, and then dec-9-enoic acid methyl ester was slowly added dropwise, reacted in an ice bath for 40-90 min, then heated to 30-40° C. and reacted for 12-16 h, and distilled under reduced pressure to obtain intermediate 1, the reaction equation of which is shown as follows:

[0010]

[0011] S2: Under nitrogen protection, add DMSO, citric acid and intermediate 1 to the reactor, stir, heat to 95-125°C, then add p-toluenesulfonic acid, react for 4-8h, and post-treat to obtain intermediate 2, the reaction equation of which is shown as follows:

[0012]

[0013] S3: Under nitrogen protection, acetonitrile, intermediate 2 and potassium carbonate were added to the reactor, stirred, and acryloyl chloride was slowly added dropwise under ice bath, and reacted for 20-24 hours under light-proof conditions. Intermediate 3 was obtained after post-treatment. The reaction equation is shown as follows:

[0014]

[0015] S4: Add intermediate 3 and deionized water to the reactor, stir to dissolve, then add H2O2, stir for 15-25 minutes, and at the same time, uniformly drop an aqueous solution of ammonium persulfate, a mixed aqueous solution of acrylic acid and sodium methacrylic acid sulfonate. After the dropwise addition is complete, heat to 70-80°C and keep the temperature for 2-3 hours. Adjust the pH to 7 with an aqueous sodium hydroxide solution to obtain a modified polycarboxylic acid water reducer. The reaction equation is as follows:

[0016]

[0017] o, p, q are natural numbers.

[0018] In the step S1, the feed mass ratio of methanol, 9-amino-1-nonanol, and dec-9-enoic acid methyl ester is 50:(8-10):(10-25).

[0019] In the step S2, the mass ratio of DMSO, citric acid, intermediate 1 and p-toluenesulfonic acid is 50:(4-6):(12-18):(0.1-0.3).

[0020] In the step S3, the mass ratio of acetonitrile, intermediate 2, potassium carbonate and acryloyl chloride is 30:(5-7):(6-12):(3-6).

[0021] In the step S4, the feed mass ratio of deionized water, intermediate 3 and H2O2 is 50:(20-30):(4-6).

[0022] The defoamer is one of polyether ester defoamer SGR1820 and silicone defoamer SGR1830.

[0023] A method for preparing composite drag-reducing and viscosity-reducing concrete for high-lift pumping comprises the following steps:

[0024] (1) Weigh by weight: cement: 100-120 parts, machine-made sand: 50-70 parts, silica fume: 15-25 parts, deionized water: 30-50 parts, defoamer: 2-5 parts, modified polycarboxylic acid water reducer: 5-10 parts;

[0025] (2) Cement, modified polycarboxylic acid water-reducing agent and defoaming agent are mixed evenly to obtain a mixture; then the mixture, machine-made sand, silica powder and deionized water are mixed evenly to obtain a composite drag-reducing and viscosity-reducing concrete.

[0026] Due to the adoption of the above technical solution, the beneficial effects of the present invention include:

[0027] (1) The present invention prepares intermediate 1 by reacting 9-amino-1-nonanol and dec-9-enoic acid methyl ester, then reacts intermediate 1 with citric acid to prepare intermediate 2, then reacts intermediate 2 with acryloyl chloride to prepare intermediate 3, and finally acrylic acid, intermediate 3 and sodium methyl methacrylate are reacted by free radical polymerization to prepare a modified polycarboxylic acid water reducer.

[0028] (2) The intermediate 3 prepared by the present invention has a six-arm structure with a large number of methoxy groups at its ends, which increases the contact points between the water reducer and the cement particles and improves the bonding force between the water reducer and the cement particles; at the same time, the six-arm tree-branch structure can increase the steric effect. When added to cement, the cement has better dispersibility and prevents cement agglomeration. At a lower dosage, the prepared concrete can also have good fluidity.

[0029] (3) The modified polycarboxylic acid water reducer prepared by the present invention is synthesized by free radical copolymerization of intermediate 3 and acrylic acid monomer to obtain a six-arm side chain modified polycarboxylic acid water reducer. The main chain of the prepared water reducer contains carboxyl and sulfonic acid groups, which are attached to the surface of cement particles by complexing with calcium ions. When the cement particles are close to each other, the long side chains of the water reducer will produce spatial hindrance, making it difficult for the cement particles to approach each other, thereby increasing the release of free water in the cement system, thereby achieving a water reduction effect. DETAILED DESCRIPTION

[0030] The invention will be further described below in conjunction with the embodiments, but the invention is not limited to these embodiments.

[0031] Example 1

[0032] Preparation of modified polycarboxylate water reducer:

[0033] S1: Under nitrogen protection, 500 g of methanol and 80 g of 9-amino-1-nonanol were added to the reactor, and the mixture was stirred in an ice-water bath. Then, 100 g of dec-9-enoic acid methyl ester was slowly added dropwise for 0.5 h. After the addition was completed, the mixture was reacted in an ice bath for 40 min, and then the temperature was raised to 30° C. and reacted for 16 h. The mixture was distilled under reduced pressure at 50° C. for 40 min to obtain intermediate 1;

[0034] S2: Under nitrogen protection, add 500g DMSO, 40g citric acid and 120g intermediate 1 into the reactor, stir, heat to 95°C, then add 1g p-toluenesulfonic acid, react for 4-8h, wash with saturated NaHCO3 solution until neutral, and distill under reduced pressure at 50°C for 2h to obtain intermediate 2;

[0035] S3: Under nitrogen protection, add 300 g acetonitrile, 50 g intermediate 2 and 60 g potassium carbonate to the reactor, stir, slowly add 30 g acryloyl chloride dropwise under ice bath, add dropwise for 10 min, react for 24 h in dark conditions, filter, and vacuum dry at 50 °C for 3 h to obtain intermediate 3;

[0036] S4: Add 200g of intermediate 3 and 500g of deionized water to the reactor, stir to dissolve, then add 40g of H2O2, stir for 15min, and simultaneously dropwise add an aqueous solution of ammonium persulfate (2g of ammonium persulfate dissolved in 30g of deionized water) and a mixed solution of acrylic acid and sodium methacrylic acid (25g of acrylic acid and 50g of sodium methacrylic acid dissolved in 100g of deionized water) at a uniform rate, dropwise for 1h, and after the dropwise addition is completed, heat to 70°C and keep warm for 3h to react, adjust the pH to 7 with a 30wt% aqueous solution of sodium hydroxide to obtain a modified polycarboxylic acid water reducer.

[0037] Example 2

[0038] Preparation of modified polycarboxylate water reducer:

[0039] S1: Under nitrogen protection, 500 g of methanol and 90 g of 9-amino-1-nonanol were added to the reactor, and the mixture was stirred in an ice-water bath. Then, 175 g of dec-9-enoic acid methyl ester was slowly added dropwise for 0.5 h. After the addition was completed, the mixture was reacted in an ice bath for 1 h. Then, the mixture was heated to 35 °C and reacted for 14 h. The mixture was distilled under reduced pressure at 50 °C for 40 min to obtain intermediate 1;

[0040] S2: Under nitrogen protection, 500 g DMSO, 50 g citric acid and 150 g intermediate 1 were added to the reactor, stirred, heated to 110°C, and then 2 g p-toluenesulfonic acid was added. The mixture was reacted for 6 h, washed with saturated NaHCO3 solution until neutral, and distilled under reduced pressure at 60°C for 1.5 h to obtain intermediate 2;

[0041] S3: Under nitrogen protection, 300 g of acetonitrile, 60 g of intermediate 2 and 90 g of potassium carbonate were added to the reactor, stirred, and 45 g of acryloyl chloride was slowly added dropwise under ice bath for 12 min. The mixture was reacted for 22 h in dark conditions, filtered, and dried under vacuum at 60 °C for 3 h to obtain intermediate 3;

[0042] S4: Add 250g of intermediate 3 and 500g of deionized water to the reactor, stir to dissolve, then add 50g of H2O2, stir for 20min, and simultaneously add dropwise at a uniform rate an aqueous solution of ammonium persulfate (3g of ammonium persulfate dissolved in 35g of deionized water), a mixed solution of acrylic acid and sodium methacrylic acid (30g of acrylic acid and 60g of sodium methacrylic acid dissolved in 125g of deionized water), add dropwise for 1h, after the addition is complete, heat to 75°C and keep warm for 2.5h to react, adjust the pH to 7 with a 30wt% aqueous solution of sodium hydroxide to obtain a modified polycarboxylic acid water reducer.

[0043] Example 3

[0044] Preparation of modified polycarboxylate water reducer:

[0045] S1: Under nitrogen protection, 500 g of methanol and 100 g of 9-amino-1-nonanol were added to the reactor, stirred in an ice-water bath, and then 250 g of dec-9-enoic acid methyl ester was slowly added dropwise for 0.5 h. After the addition was completed, the mixture was reacted in an ice bath for 90 min, then the temperature was raised to 40 ° C and reacted for 12 h, and the mixture was distilled at 50 ° C under reduced pressure for 60 min to obtain intermediate 1;

[0046] S2: Under nitrogen protection, 500 g DMSO, 60 g citric acid and 180 g intermediate 1 were added to the reactor, stirred, heated to 125 ° C, and then 3 g p-toluenesulfonic acid was added. The reaction was continued for 4 h, washed with saturated NaHCO3 solution until neutral, and distilled under reduced pressure at 70 ° C for 1 h to obtain intermediate 2;

[0047] S3: Under nitrogen protection, add 300 g acetonitrile, 70 g intermediate 2 and 120 g potassium carbonate to the reactor, stir, slowly add 60 g acryloyl chloride dropwise under ice bath, add dropwise for 15 min, react for 20 h in dark conditions, filter, and vacuum dry at 65 °C for 3 h to obtain intermediate 3;

[0048] S4: Add 300g of intermediate 3 and 500g of deionized water to the reactor, stir to dissolve, then add 60g of H2O2, stir for 25min, and then uniformly add aqueous ammonium persulfate solution (5g of ammonium persulfate dissolved in 50g of deionized water) and a mixed solution of acrylic acid and sodium methacrylic acid sulfonate (40g of acrylic acid and 70g of sodium methacrylic acid sulfonate dissolved in 150g of deionized water) dropwise for 1h. After the addition is completed, the temperature is raised to 80°C and kept warm for 2h. The pH is adjusted to 7 with a 30wt% sodium hydroxide aqueous solution to obtain a modified polycarboxylic acid water reducer.

[0049] Example 4

[0050] Preparation of reduced viscosity concrete:

[0051] S1: weigh: cement: 1000g, machine-made sand: 500g, silica fume: 150g, deionized water: 300g, defoamer (organic silicon defoamer SGR1830): 20g, modified polycarboxylic acid water reducer (prepared in Example 1): 50g;

[0052] S2: Cement, modified polycarboxylic acid water-reducing agent and defoaming agent were stirred and mixed for 20 minutes to obtain a mixture; then the mixture, machine-made sand, silica powder and deionized water were stirred and mixed for 25 minutes to obtain a composite drag-reducing and viscosity-reducing concrete.

[0053] Example 5

[0054] Preparation of reduced viscosity concrete:

[0055] S1: weigh: cement: 1100g, machine-made sand: 600g, silica fume: 200g, deionized water: 400g, defoamer (polyether ester defoamer SGR1820): 35g, modified polycarboxylic acid water reducer (prepared in Example 2): 75g;

[0056] S2: Cement, modified polycarboxylic acid water-reducing agent and defoaming agent are stirred and mixed for 20 minutes to obtain a mixture; then the mixture, machine-made sand, silica powder and deionized water are stirred and mixed for 30 minutes to obtain a composite drag-reducing and viscosity-reducing concrete.

[0057] Example 6

[0058] Preparation of reduced viscosity concrete:

[0059] S1: weigh: cement: 1200g, machine-made sand: 700g, silica fume: 250g, deionized water: 500g, defoamer (organic silicon defoamer SGR1830): 50g, modified polycarboxylic acid water reducer (prepared in Example 3): 100g;

[0060] S2: Cement, modified polycarboxylic acid water-reducing agent and defoaming agent are stirred and mixed for 20 minutes to obtain a mixture; then the mixture, machine-made sand, silica powder and deionized water are stirred and mixed for 40 minutes to obtain a composite drag-reducing and viscosity-reducing concrete.

[0061] Comparative Example 1

[0062] The raw material composition and process of the viscosity-reducing concrete are substantially the same as those of Example 5, except that no modified polycarboxylic acid water-reducing agent is added to the composition.

[0063] Comparative Example 2

[0064] The raw material composition and process of the viscosity-reducing concrete are basically the same as those in Example 5, except that the modified polycarboxylate water-reducing agent is replaced by an equal weight of a polycarboxylate water-reducing agent prepared by the following method:

[0065] S1: Under nitrogen protection, 500 g of methanol and 90 g of 9-amino-1-nonanol were added to the reactor, stirred in an ice-water bath, and then 175 g of dec-9-enoic acid methyl ester was slowly added dropwise for 0.5 h. After the addition was completed, the reaction was continued in an ice bath for 1 h, and then reacted at 35 ° C for 14 h, and distilled at 50 ° C for 40 min to obtain intermediate 1;

[0066] S2: Under nitrogen protection, 500 g DMSO, 50 g DL-malic acid and 150 g intermediate 1 were added to the reactor, stirred, heated to 110 ° C, and then 2 g p-toluenesulfonic acid was added. The reaction was continued for 6 h, washed with saturated NaHCO3 solution until neutral, and distilled under reduced pressure at 60 ° C for 1.5 h to obtain intermediate 2;

[0067] S3: Under nitrogen protection, add 300 g acetonitrile, 60 g intermediate 2 and 90 g potassium carbonate to the reactor, stir, slowly add 45 g acryloyl chloride dropwise under ice bath, add dropwise for 12 min, react for 22 h in dark conditions, filter, and vacuum dry at 60 °C for 1.5 h to obtain intermediate 3;

[0068] S4: Add 250g of intermediate 3 and 500g of deionized water to the reactor, stir to dissolve, then add 50g of H2O2, stir for 20min, and simultaneously add dropwise at a uniform rate an aqueous solution of ammonium persulfate (3g of ammonium persulfate dissolved in 35g of deionized water), a mixed solution of acrylic acid and sodium methacrylic acid (30g of acrylic acid and 60g of sodium methacrylic acid dissolved in 125g of deionized water), add dropwise for 1h, after the addition is complete, heat to 75°C and keep warm for 2.5h to react, adjust the pH to 7 with a 30wt% aqueous solution of sodium hydroxide to obtain a modified polycarboxylic acid water reducer.

[0069] Comparative Example 3

[0070] The raw material composition and process of the viscosity-reducing concrete are basically the same as those in Example 5, except that the modified polycarboxylate water-reducing agent is replaced by an equal weight of a polycarboxylate water-reducing agent prepared by the following method:

[0071] (1) Add 25 ml of methanol and 7 ml of ethanolamine to the reactor, and slowly add 30 ml of methyl acrylate dropwise for half an hour under nitrogen protection in an ice bath. Continue to react in an ice bath for half an hour, and then react in an oil bath at 30°C in the dark for 16 hours. Drain under reduced pressure at 30°C to obtain a colorless oily substance, which is the product 0.5 generation polyamidoamine dendrimer (PAMAM) hyperbranched molecule (G0.5).

[0072] (2) The obtained G0.5 is passed through a silica gel column using ethanol as a single-component eluent, the components are collected, and then distilled under reduced pressure to dryness to obtain relatively pure G0.5.

[0073] (3) Take 5.8 g of purified G0.5 and add 25 mL of methanol. In an ice bath, add the mixture of 40 mL of ethylenediamine and 25 mL of methanol. The addition is completed within half an hour under nitrogen protection. The ice bath is continued for half an hour. Then, the reaction is carried out under nitrogen protection and light protection at 30°C for 48 hours. The reaction is dried under reduced pressure at 55°C, and then the mixture is azeotroped 2-3 times with a mixture of methanol:toluene in a ratio of 1:9 to remove excess ethylenediamine. The residual toluene is then azeotroped 2-3 times with methanol to obtain a colorless viscous oily substance, which is a 1.0 generation PAMAM hyperbranched molecule (G1).

[0074] (4) Take 0.1 mol of chloromethoxy polyethylene glycol (Mn=600), put it into 100 mL of acetonitrile, add 0.2 mol of potassium carbonate and 1% of the mass of potassium iodide and 0.02 mol of G1, reflux for 24 h under nitrogen protection at 85°C and in the dark, filter with a sand core funnel, and drain. All the products obtained in the previous step are added to 80 mL of acetonitrile, and then 0.2 mol of potassium carbonate is added, 0.06 mol of acryloyl is dissolved in 20 mL of acetonitrile, added dropwise in an ice bath, reacted for 24 h under nitrogen protection in the dark, filtered and drained, and a four-arm hyperbranched polyoxyethylene ether macromonomer is obtained.

[0075] (5) Add 250 g of four-arm hyperbranched polyoxyethylene ether macromonomer and 500 g of deionized water to the reactor, stir to dissolve, then add 50 g of H2O2, stir for 20 min, and then uniformly add an aqueous solution of ammonium persulfate (3 g of ammonium persulfate dissolved in 35 g of deionized water) and a mixed solution of acrylic acid and sodium methacrylic acid (30 g of acrylic acid and 60 g of sodium methacrylic acid dissolved in 125 g of deionized water) dropwise for 1 h. After the addition is complete, the temperature is raised to 75° C. and the reaction is kept warm for 2.5 h. The pH is adjusted to 7 with a 30 wt % aqueous solution of sodium hydroxide to obtain a modified polycarboxylic acid water reducer.

[0076] Comparative Example 4

[0077] The raw material composition and process of the viscosity-reducing concrete are basically the same as those of Example 5, except that the modified polycarboxylic acid water-reducing agent is replaced by an equal weight of polycarboxylic acid high-performance water-reducing agent (SPC-100).

[0078] Comparative Example 5

[0079] The raw material composition and process of the viscosity-reducing concrete are basically the same as those in Example 5, except that the modified polycarboxylate water-reducing agent is replaced by an equal weight of a polycarboxylate water-reducing agent prepared by the following method:

[0080] Add 200g of ethylene glycol monovinyl polyethylene glycol ether (EPEG3000) and 500g of deionized water to the reactor, stir for 10min, add 2g of initiator H2O2 to the reactor, stir for 5min, and then drop 50g of acrylic acid, 5g of ascorbic acid and 25g of sodium allyl sulfonate for 15min. After the dropwise addition, keep warm for 2h. After the reaction is completed, adjust the pH to 7 with 30wt% sodium hydroxide aqueous solution to obtain a transparent viscous polycarboxylate water reducer.

[0081] Comparative Example 6

[0082] A LC40 fully light pumpable ceramsite concrete is produced using the raw material composition and process of Example 1 of the Chinese invention patent with publication number CN114956712A.

[0083] The specification of the machine-made sand used in the embodiments and comparative examples of the present application is 1.55-4.75 mm, purchased from Wuhan Deyi Environmental Protection New Materials Co., Ltd.; the cement is road silicate cement grade 42.5 (code P.R7.5), purchased from Shanxi Excellence Cement Co., Ltd.; polyether ester defoamer SGR1820 and silicone defoamer SGR1830 were purchased from Xingrui (Shandong) Environmental Technology Co., Ltd.; the specification of silica powder is 40-200 mesh, purchased from Shanghai McLean Biochemical Technology Co., Ltd.; ethylene glycol monovinyl polyethylene glycol ether (EPEG3000) was purchased from Liaoning Aoke Chemical Co., Ltd.; polycarboxylic acid high-performance water reducer (SPC-100) was purchased from Liaoning Kelong Fine Chemical Co., Ltd.

[0084] The concrete that has been fully mixed by a concrete mixer is molded and sampled, and placed in a curing box with a temperature of 20±5℃ and a humidity of 95% for curing. The molds are removed after 8 days of curing, and the demoulding test blocks are placed in the curing box for further curing. When the curing reaches the specified age, the compressive strength is measured using a compressive strength testing machine.

[0085] The compressive strength of concrete was determined according to GB / T 50081-2002.

[0086] The water reduction rate and fluidity of concrete paste were determined according to GB / T 8077-2012.

[0087] Table 1 Concrete performance indicators

[0088]

[0089]

[0090] It can be seen from Table 1 that the composite drag-reducing and viscosity-reducing concrete prepared in Examples 4 to 6 of the present application has excellent compressive strength, water reduction rate and neat paste fluidity.

[0091] Comparative Example 1 is a comparative example prepared without adding modified polycarboxylic acid water-reducing agent. It can be seen from the data in Table 1 that its compressive strength is 42.3 MPa after 28 days, the water reduction rate is 20%, and the net paste fluidity at 60 minutes is 245 mm. The prepared concrete has poor compressive strength and poor net paste fluidity loss performance over time.

[0092] In Comparative Example 2, the citric acid added in step S2 during the preparation of the modified polycarboxylic acid water-reducing agent is replaced with DL-malic acid. As can be seen from Table 1, the compressive strength after 28 days is 52.9 MPa, the water reduction rate is 31%, and the net slurry fluidity at 60 minutes is 286 mm. The prepared concrete has poorer compressive strength than that prepared in Example 5, and the net slurry fluidity loss performance over time is average.

[0093] In Comparative Example 3, the intermediate 3 prepared in step S3 in the preparation process of the modified polycarboxylic acid water-reducing agent is replaced with an equal weight of a four-arm hyperbranched polyoxyethylene ether macromonomer. As can be seen from Table 1, the compressive strength is 47.7 MPa after 28 days, the water reduction rate is 25%, and the net slurry fluidity at 60 minutes is 256 mm, indicating that the time-loss performance of the net slurry fluidity using the four-arm hyperbranched macromonomer is generally comparable to that in Example 5.

[0094] The modified polycarboxylic acid water-reducing agent added in Comparative Example 4 is a polycarboxylic acid high-performance water-reducing agent (SPC-100). As can be seen from Table 1, its compressive strength after 28 days is 49.4 MPa, the water reduction rate is 27%, and the net paste fluidity at 60 minutes is 261 mm, indicating that the concrete net paste fluidity loss performance over time of the water-reducing agent is average.

[0095] Comparative Example 5 is a polycarboxylic acid water-reducing agent prepared using ethylene glycol monovinyl polyethylene glycol ether. As can be seen from Table 1, its compressive strength after 28 days is 51.2 MPa, the water reduction rate is 28%, and the net slurry fluidity at 60 minutes is 273 mm. Its compressive strength is good, but the net slurry fluidity loss performance over time is average.

[0096] Comparative Example 6 is LC40 fully light pumped ceramsite concrete produced by the raw material composition and process in Example 1 of the Chinese invention patent CN114956712A. As can be seen from Table 1, its compressive strength after 28 days is 51.7 MPa, the water reduction rate is 30%, and the net slurry fluidity at 60 minutes is 277 mm. Although the compressive strength is high, the net slurry fluidity loss performance over time is poor.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. However, any equivalent changes, modifications and evolutions made by ordinary technicians in the field without departing from the scope of the technical solution of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A composite drag-reducing and viscosity-reducing concrete for high-lift pumping, characterized in that: The composite drag-reducing and viscosity-reducing concrete comprises the following raw materials in parts by weight: Cement: 100-120 parts, Machine-made sand: 50-70 parts, Silicon powder: 15-25 parts, Deionized water: 30-50 parts, Defoaming agent: 2-5 parts, Modified polycarboxylic acid water reducer: 5-10 parts; The modified polycarboxylate water-reducing agent is prepared by the following method: S1: Under nitrogen protection, methanol and 9-amino-1-nonanol were added to the reactor, stirred in an ice-water bath, and then dec-9-enoic acid methyl ester was slowly added dropwise, reacted in an ice bath for 40-90 min, then heated to 30-40° C. and reacted for 12-16 h, and distilled under reduced pressure to obtain intermediate 1; S2: Under nitrogen protection, add DMSO, citric acid and intermediate 1 to the reactor, stir, heat to 95-125°C, then add p-toluenesulfonic acid, react for 4-8h, and post-treat to obtain intermediate 2; S3: Under nitrogen protection, acetonitrile, intermediate 2 and potassium carbonate were added to the reactor, stirred, and acryloyl chloride was slowly added dropwise under ice bath, reacted for 20-24 hours under light-proof conditions, and post-treated to obtain intermediate 3; S4: Add intermediate 3 and deionized water to the reactor, stir to dissolve, then add H2O2, stir for 15-25 minutes, and at the same time, uniformly add aqueous solution of ammonium persulfate, acrylic acid and sodium methacrylic acid mixed aqueous solution. After the addition is complete, heat to 70-80°C and keep warm for 2-3 hours. Adjust pH to 7 with aqueous sodium hydroxide to obtain a modified polycarboxylic acid water reducer.

2. The composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to claim 1, characterized in that: In the step S1, the feed mass ratio of methanol, 9-amino-1-nonanol, and dec-9-enoic acid methyl ester is 50:(8-10):(10-25).

3. The composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to claim 1, characterized in that: In the step S2, the mass ratio of DMSO, citric acid, intermediate 1 and p-toluenesulfonic acid is 50:(4-6):(12-18):(0.1-0.3).

4. The composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to claim 1, characterized in that: In the step S3, the feed mass ratio of acetonitrile, intermediate 2, potassium carbonate and acryloyl chloride is 30:(5-7):(6-12):(3-6).

5. The composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to claim 1, characterized in that: In the step S4, the feed mass ratio of deionized water, intermediate 3 and H2O2 is 50:(20-30):(4-6).

6. The composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to claim 1, characterized in that: The defoamer is one of polyether ester defoamer SGR1820 and silicone defoamer SGR1830.

7. A method for preparing the composite drag-reducing and viscosity-reducing concrete for high-lift pumping according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Weigh by weight: cement: 100-120 parts, machine-made sand: 50-70 parts, silica fume: 15-25 parts, deionized water: 30-50 parts, defoamer: 2-5 parts, modified polycarboxylic acid water reducer: 5-10 parts; (2) Cement, modified polycarboxylic acid water-reducing agent and defoaming agent are mixed evenly to obtain a mixture; then the mixture, machine-made sand, silica powder and deionized water are mixed evenly to obtain a composite drag-reducing and viscosity-reducing concrete.

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