A marine engineering low-carbon, high-ductility cement-based material

Abstract

This invention provides a low-carbon, high-ductility cement-based material for marine engineering and its preparation method, mainly comprising the following raw materials: silicate cement, calcined clay, limestone powder, fly ash, river sand, gypsum, water-reducing agent, modified polyvinyl alcohol fiber, latex powder, and triethanolamine. The modified polyvinyl alcohol fiber is used in this invention. The calcined clay raw material is kaolin tailings, which, after calcination, exhibits high chemical activity and strong chloride ion binding capacity. The high proportion of solid waste utilization gives this cement-based material low-carbon characteristics. Latex powder increases the bonding force between the polymer fiber and the cement matrix, improving the toughness and ultimate tensile strength of the fiber composite material. Fly ash, as an auxiliary cementitious material, improves the flowability of the composite material and further enhances the green and low-carbon level of the substrate. After the raw materials of this invention are compounded, the cement-based material has high setting efficiency and good mechanical properties such as flexural and compressive strength.

Description

Technical Field

[0001] This invention relates to the field of cement technology, and in particular to a low-carbon, high-ductility cement-based material for marine engineering. Background Technology

[0002] Cement concrete, as the most widely used building material, plays an irreplaceable role in marine development. The performance requirements for cement-based materials in marine engineering structures go beyond compressive strength; in many cases, excellent bending resistance, impact resistance, and durability are also required. This necessitates overcoming the problems of high heat generation, brittleness, poor toughness, and susceptibility to cracking inherent in traditional cement concrete. Currently, high-ductility cementitious materials (ECC) are used in structural repair and reinforcement, but their application in marine engineering is not widespread. A key reason for this is the high cost and carbon emissions of ECC materials, and their corrosion resistance in marine environments has not been fully verified. This invention provides a novel cementitious material, composed of calcined clay, limestone powder, gypsum, and a portion of clinker, with the cement clinker content reduced by approximately 40% compared to ordinary Portland cement. Existing research results indicate that LC cement with a similar composition to this invention… 3 Cementitious materials possess a relatively dense microstructure and strong chloride ion binding capacity, exhibiting strong resistance to seawater erosion. However, they have low flexural strength and weak impact resistance. If low-carbon cementitious materials are used as the matrix, combined with the design concept of high-ductility ECC materials, it may be possible to create a low-carbon, eco-friendly, high-toughness, and low-cost marine engineering low-carbon cement-based material. Patent CN116903334A discloses a low-carbon, low-shrinkage ECC material and its preparation method. This patent uses a large proportion of calcined clay and limestone powder to replace cement. By weight, it uses ordinary silicate cement, calcined clay, limestone powder, quartz sand, PVA fiber, water, high-efficiency water-reducing agent, and calcium sulfate whiskers to prepare LC. 3 The material exhibits a maximum direct tensile strain of only 2.6% after 28 days, indicating low crack control and tensile ductility. Furthermore, its durability was not measured. Patent CN117105595A discloses a low-carbon ECC material and its preparation method. This method uses a large amount of calcined clay and lightly calcined dolomite powder to replace ordinary silicate cement, comprising the following raw material components: cement, calcined clay, lightly calcined dolomite powder, quartz sand, PVA fiber, and a high-efficiency water-reducing agent. This technical solution does not record relevant durability test results, and the presence of dolomite powder with significant compositional fluctuations in the formulation somewhat affects the stability of the ECC material. Summary of the Invention

[0003] In view of this, the present invention proposes a low-carbon, high-ductility cement-based material for marine engineering to solve the above problems.

[0004] The technical solution of this invention is implemented as follows:

[0005] A marine engineering low-carbon, high-ductility cement-based material, characterized in that, by weight, it comprises the following components: 25-100 parts silicate cement, 10-60 parts calcined clay, 5-30 parts limestone powder, 60-110 parts fly ash, 55-100 parts river sand, 1-3 parts gypsum, 1-2 parts water-reducing agent, 2-3 parts modified polyvinyl alcohol fiber, 0.5-1.0 parts latex powder, 0.1-0.3 parts triethanolamine, and 45-100 parts water.

[0006] The preparation method of modified polyvinyl alcohol fiber includes the following steps:

[0007] S1. Surface modification of PVA fibers by spraying adhesive: water-soluble polyvinyl alcohol, diethylene glycol dibenzoate, epoxy modified silicone oil, rubber powder, penetrant and water are mixed, stirred, heated, kept at a constant temperature to homogenize, and cooled to room temperature to obtain the initial adhesive solution.

[0008] S2. Apply the initial adhesive solution to the PVA fiber to obtain a nonwoven fabric. Dry the nonwoven fabric, heat-roll it, fix it, calender it, cool it, and roll it up to obtain modified polyvinyl alcohol fiber.

[0009] Furthermore, the mass ratio of the water-soluble polyvinyl alcohol, diethylene glycol dibenzoate, epoxy-modified silicone oil, rubber powder, penetrant, and water is 90-110:30-50:8-10:5-8:0.3-0.6:450-500; the epoxy-modified silicone oil is prepared by mixing vinylepoxycyclohexane and low-hydrogen silicone oil, using toluene as a solvent, and heating; the low-hydrogen silicone oil has an active hydrogen molar fraction of 0.06%-0.07% and a viscosity of 800-900 mPa·s; the vinylepoxycyclohexane and toluene are of analytical grade; the heating is carried out under nitrogen protection at a temperature of 80-85℃ for 6-8 hours.

[0010] Furthermore, the degree of alcoholysis of the water-soluble polyvinyl alcohol is 90%-99%, the degree of polymerization is 1000-1500, the penetrant is one of penetrant JFC-1, penetrant JFC-2, and penetrant JFC-E, and the fineness of the modified polyvinyl alcohol fiber is 15-20 tex.

[0011] Further, S1, the stirring rate is 200-220 rpm, the heating temperature is 95-100℃, and the heating time is 1.5-2 h; the heat preservation and homogenization temperature is 80-85℃, and the time is 1.0-1.5 h; S2, the nonwoven fabric preparation method is dry nonwoven fabric preparation, the drying temperature is 40-55℃, the hot rolling temperature is 180-200℃, the spinning speed is 700-900 m / min, and the cooling method is annular blowing, the blowing temperature is 10-20℃, and the annular blowing speed is 0.2-10 m / min.

[0012] Furthermore, the silicate cement is PI42.5 type silicate cement, and its mineral composition by mass is as follows: C2S 18%-25%, C3S 55%-60%, C4AF 8.5%-10%, and C3A 5.5%-8%. The initial setting time of the silicate cement is 115-125 min, the final setting time is 180-190 min, the 3-day compressive strength is >17.0 MPa, the 3-day flexural strength is >3.5 MPa, the 28-day compressive strength is >42.5 MPa, and the 28-day flexural strength is >6.5 MPa.

[0013] Furthermore, the calcined clay is obtained by calcining and grinding kaolin tailings at 750-800℃, with a particle size range of 0.1-30 micrometers and a specific surface area of ​​1.51-1.53 ​​m². 2 / g. The limestone powder is heavy calcium carbonate powder, with a particle size range of 0.3-30 micrometers and a specific surface area of ​​2.90-2.92 m². 2 / g, calcium carbonate content >95%.

[0014] Furthermore, the fly ash is secondary fly ash with a particle size range of 0.3-200 micrometers, the river sand has a particle size of 0.1-0.6 mm (natural river sand), the gypsum is analytical grade dihydrate gypsum, and the water-reducing agent is polycarboxylate water-reducing agent with a solid content of 18%-22% and a water reduction rate of 35%-40%.

[0015] Furthermore, the latex powder is a mixture of vinyl acetate and ethylene copolymer powder in a mass ratio of 1:1.1-1.3, or a mixture of acrylate and styrene copolymer powder in a mass ratio of 1:1.2-1.4.

[0016] A method for preparing a low-carbon, high-ductility cement-based material for marine engineering, characterized by comprising the following steps:

[0017] S1. Mix silicate cement, calcined clay, limestone powder and gypsum at a stirring speed of 90-100 prm / min for 2-3 minutes to obtain a powder mixture; add fly ash and river sand to the powder mixture and mix at a stirring speed of 90-100 prm / min for 2-3 minutes to obtain mixture I.

[0018] S2. Mix the water-reducing agent, triethanolamine and water, and add the mixture evenly to mixture I at a stirring speed of 90-100 prm / min. Stir at a speed of 160-170 prm / min for 2-3 minutes to obtain mixture II.

[0019] S3. Under stirring at a speed of 90-100 prm, add the modified polymer fiber and latex powder evenly to mixture II, stir at a speed of 160-170 prm / min for 2-3 minutes to obtain mixture III;

[0020] S4. Transfer the mixture III into the mold, vibrate for 1-2 minutes, smooth and shape, and demold and cure after 22-24 hours to obtain a high-ductility low-carbon cement-based material.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] (1) The raw material for calcined clay used in this invention is kaolin tailings, which contains a certain proportion of kaolin, a composite of silicon dioxide and aluminum oxide. After high-temperature calcination, the kaolin becomes metakaolin, which has higher chemical activity and a stronger chloride ion binding capacity. This gives the high-ductility, low-carbon cement-based material of this invention excellent mechanical properties and resistance to seawater corrosion.

[0023] (2) This invention uses cementitious materials with a high content of solid waste to prepare marine engineering high-ductility cement-based materials, which have green and low-carbon characteristics. The firing temperature of cement clinker is 1250℃, while the firing temperature of calcined clay is about 800℃, which greatly reduces the carbon emissions of marine engineering materials. The use of low-carbon cementitious materials to prepare marine engineering high-ductility cement-based materials greatly reduces the heat of hydration of the material, which can effectively reduce the risk of cracking in marine structures during construction.

[0024] (3) The present invention uses redispersible latex powder and modified polyvinyl alcohol fiber, which can enhance the bonding force between the cement matrix and the fiber interface and improve the ultimate tensile strength of fiber reinforced composite material.

[0025] (4) This invention uses a relatively high proportion of secondary fly ash as an auxiliary cementitious material, which can improve the workability of low-carbon cement-based material mixtures by utilizing its ball-bearing effect. In addition, the secondary fly ash used is a low-quality industrial solid waste, which is widely available and inexpensive. Using it to prepare high-ductility cement-based materials can improve the carbon reduction and emission reduction level of low-carbon materials. Attached Figure Description

[0026] Figure 1 Example 1: Tensile stress diagram. Detailed Implementation

[0027] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention.

[0028] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0029] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0030] The low-hydrogen silicone oil was purchased from Jinan Shanhai Chemical Technology Co., Ltd.; the kaolin tailings came from Beihai Kaolin Technology Co., Ltd., and were generated from the fourth-stage bottom slag solid waste produced by the fourth-stage hydrocyclone during the kaolin ore beneficiation process.

[0031] Preparation Example 1

[0032] The preparation method of modified polyvinyl alcohol fiber includes the following steps:

[0033] S1. Surface modification of PVA fibers by spraying adhesive: water-soluble polyvinyl alcohol, diethylene glycol dibenzoate, epoxy modified silicone oil, rubber powder, penetrant and water in a mass ratio of 90:30:8:5:0.4:450 are mixed and stirred at a stirring speed of 200 rpm. Then, the mixture is heated to 100℃, kept at 80℃ for 1.0 h for homogenization, and cooled to room temperature to obtain the initial adhesive solution.

[0034] Among them, the epoxy modified silicone oil is prepared by mixing vinyl epoxy cyclohexane and low hydrogen content silicone oil, using toluene as solvent, and heating. The low hydrogen content silicone oil has an active hydrogen molar fraction of 0.06% and a viscosity of 800 mPa·s. The vinyl epoxy cyclohexane and toluene are of analytical grade. Heating is carried out under nitrogen protection at a temperature of 85℃ for 8 hours.

[0035] The water-soluble polyvinyl alcohol has a degree of alcoholysis of 90% and a degree of polymerization of 1000; the penetrant is penetrant JFC-1, and the fineness of the modified polyvinyl alcohol fiber is 20 tex.

[0036] S2. Apply the initial sizing solution to the PVA fibers using a dry nonwoven fabric preparation method. The spinning speed is 700 m / min. The nonwoven fabric is then dried at 55°C, hot-rolled at 200°C, fixed, calendered, and cooled using an annular air blowing system at 10°C and a speed of 2 m / min. Finally, it is wound up to obtain modified polyvinyl alcohol fibers.

[0037] Preparation Example 2

[0038] The preparation method of modified polyvinyl alcohol fiber includes the following steps:

[0039] S1. Surface modification of PVA fibers by spraying adhesive: water-soluble polyvinyl alcohol, diethylene glycol dibenzoate, epoxy modified silicone oil, rubber powder, penetrant and water in a mass ratio of 110:50:10:8:0.6:500 are mixed and stirred at a stirring speed of 220 rpm. Then, the mixture is heated to 100℃, kept at 85℃ for 1.5 hours for homogenization, and cooled to room temperature to obtain the initial adhesive solution.

[0040] Among them, the epoxy modified silicone oil is prepared by mixing vinyl epoxy cyclohexane and low hydrogen content silicone oil, using toluene as solvent, and heating. The low hydrogen content silicone oil has an active hydrogen molar fraction of 0.07% and a viscosity of 900 mPa·s. The vinyl epoxy cyclohexane and toluene are of analytical grade. Heating is carried out under nitrogen protection at a temperature of 85℃ for 8 hours.

[0041] The water-soluble polyvinyl alcohol has a degree of alcoholysis of 98% and a degree of polymerization of 1400; the penetrant is penetrant JFC-2; and the fineness of the modified polyvinyl alcohol fiber is 20 tex.

[0042] S2. Apply the initial sizing solution to the PVA fibers using a dry nonwoven fabric preparation method. The spinning speed is 900 m / min. The nonwoven fabric is then dried at 55°C, hot-rolled at 200°C, fixed, calendered, and cooled using an annular air blowing system at 20°C and a speed of 9 m / min. Finally, it is wound up to obtain modified polyvinyl alcohol fibers.

[0043] Preparation Example 3

[0044] The preparation method of modified polyvinyl alcohol fiber includes the following steps:

[0045] S1. Surface modification of PVA fibers by spraying adhesive: water-soluble polyvinyl alcohol, diethylene glycol dibenzoate, epoxy modified silicone oil, rubber powder, penetrant and water in a mass ratio of 100:40:9:7:05:450 are mixed and stirred at a stirring speed of 210 rpm. Then, the mixture is heated to 95°C and kept at 80°C for 1.0 h to homogenize. After cooling to room temperature, the initial adhesive solution is obtained.

[0046] Among them, the epoxy modified silicone oil is prepared by mixing vinyl epoxy cyclohexane and low hydrogen content silicone oil, using toluene as solvent, and heating. The low hydrogen content silicone oil has an active hydrogen molar fraction of 0.06% and a viscosity of 800 mPa·s. The vinyl epoxy cyclohexane and toluene are of analytical grade. Heating is carried out under nitrogen protection at a temperature of 80℃ for 7 hours.

[0047] The water-soluble polyvinyl alcohol has a degree of alcoholysis of 90-99% and a degree of polymerization of 1000-1500; the penetrant is penetrant JFC-E; and the fineness of the modified polyvinyl alcohol fiber is 18 tex.

[0048] S2. Apply the initial sizing solution to the PVA fibers using a dry nonwoven fabric preparation method. The spinning speed is 800 m / min. The nonwoven fabric is then dried at 50°C, hot-rolled at 190°C, fixed, calendered, and cooled using an annular air blowing system at 15°C and a speed of 6 m / min. Finally, it is wound up to obtain modified polyvinyl alcohol fibers.

[0049] Example 1

[0050] A high-ductility, low-carbon cement-based material and its preparation method, wherein the raw materials comprise the following parts by weight:

[0051] 50 parts silicate cement, 32 parts calcined clay, 16 parts limestone powder, 60 parts fly ash, 56 parts river sand, 2 parts gypsum, 1 part water-reducing agent, 3 parts modified polyvinyl alcohol fiber prepared in Preparation Example 1, 1.0 part latex powder, 0.2 parts triethanolamine, and 48 parts water.

[0052] The silicate cement used is PI42.5 type silicate cement, with the following mineral composition by mass: C2S 20%, C3S 55%, C4AF 9%, C3A 6%, and a density of 3.1 g / cm³. 3 The initial setting time is 120 min, and the final setting time is 180 min.

[0053] The calcined clay is obtained by calcining and grinding kaolin tailings at 750-800℃, and has a specific surface area of ​​1.52 m². 2 / g. The limestone powder is heavy calcium carbonate powder with a particle size range of 25 micrometers and a specific surface area of ​​2.9 m². 2 / g, calcium carbonate 98%.

[0054] The fly ash is classified as secondary fly ash, with a particle size range of 150 micrometers and a specific surface area of ​​1.51 m². 2 / g; River sand with a particle size of 0.4mm is natural river sand; Gypsum is analytical grade dihydrate gypsum; Water-reducing agent is polycarboxylate water-reducing agent with a solid content of 20% and a water reduction rate of 35%.

[0055] The latex powder is a mixture of vinyl acetate and ethylene copolymer powder in a mass ratio of 1:1.1.

[0056] The production steps include:

[0057] Step (1): Mix silicate cement, calcined clay, limestone powder and gypsum at a stirring speed of 100 prm / min for 3 min to obtain a powder mixture. Add fly ash and river sand to the powder mixture and mix at a stirring speed of 100 prm / min for 3 min to obtain mixture I.

[0058] Step (2): Mix the water-reducing agent, triethanolamine and water, and add the mixture to mixture I at a constant speed of 100 prm / min. Stir at a speed of 160 prm / min for 3 minutes to obtain mixture II.

[0059] Step (3): Under a stirring speed of 100 prm, add the modified polymer fiber and latex powder evenly to mixture II, stir, the stirring speed is 160 prm / min, the time is 3 min, and mixture III is obtained;

[0060] Step (4): Transfer the mixture III into the mold, vibrate for 2 minutes, smooth and shape, and demold and cure after 24 hours to obtain a high ductility low carbon cement-based material.

[0061] Example 2

[0062] A high-ductility, low-carbon cement-based material and its preparation method, wherein the raw materials comprise the following parts by weight:

[0063] The ingredients are: 50 parts silicate cement, 40 parts calcined clay, 20 parts limestone powder, 70 parts fly ash, 60 parts river sand, 2.5 parts gypsum, 1.2 parts water-reducing agent, 2.5 parts modified polyvinyl alcohol fiber prepared in Preparation Example 2, 0.8 parts latex powder, 0.3 parts triethanolamine, and 55 parts water.

[0064] The silicate cement used is PI42.5 type silicate cement, with the following mineral composition by mass: C2S 23%, C3S 60%, C4AF 9%, C3A 7%, and a density of 3.2 g / cm³. 3 The initial setting time is 125 min, and the final setting time is 190 min.

[0065] The calcined clay is obtained by calcining and grinding kaolin tailings at 750-800℃, with a particle size range of 15 micrometers and a specific surface area of ​​1.51 m². 2 / g. The limestone powder is heavy calcium carbonate powder with a particle size range of 18 micrometers and a specific surface area of ​​2.9 m². 2 / g, calcium carbonate content 96%.

[0066] The fly ash is classified as secondary fly ash, with a particle size range of 100 micrometers and a specific surface area of ​​1.53 m². 2 / g; River sand with a particle size of 0.3mm is natural river sand; Gypsum is analytical grade dihydrate gypsum; Water-reducing agent is polycarboxylate water-reducing agent with a solid content of 22% and a water reduction rate of 40%.

[0067] The latex powder is a mixture of vinyl acetate and ethylene copolymer powder in a mass ratio of 1:1.2.

[0068] The production steps include:

[0069] Step (1): Mix silicate cement, calcined clay, limestone powder and gypsum at a stirring speed of 95 prm / min for 3 min to obtain a powder mixture. Add fly ash and river sand to the powder mixture and mix at a stirring speed of 95 prm / min for 2 min to obtain mixture I.

[0070] Step (2): Mix the water-reducing agent, triethanolamine and water, and add them evenly to mixture I at a stirring speed of 95 prm / min. Stir at a speed of 165 prm / min for 3 minutes to obtain mixture II.

[0071] Step (3): Under a stirring speed of 100 prm, add the modified polymer fiber and latex powder evenly to mixture II, stir, the stirring speed is 165 prm / min, the time is 3 min, and mixture III is obtained;

[0072] Step (4): Transfer the mixture III into the mold, vibrate for 2 minutes, smooth and shape, and demold and cure after 24 hours to obtain a high ductility low carbon cement-based material.

[0073] Example 3

[0074] A high-ductility, low-carbon cement-based material and its preparation method, wherein the raw materials comprise the following parts by weight:

[0075] 50 parts silicate cement, 35 parts calcined clay, 12 parts limestone powder, 55 parts fly ash, 50 parts river sand, 1.5 parts gypsum, 1.3 parts water-reducing agent, 2.5 parts modified polyvinyl alcohol fiber prepared in Preparation Example 3, 0.6 parts latex powder, 0.2 parts triethanolamine, and 60 parts water.

[0076] The silicate cement used is PI42.5 type silicate cement, with the following mineral composition by mass: C2S 21%, C3S 57%, C4AF 8.5%, C3A 6%, and a density of 3.2 g / cm³. 3 The initial setting time is 125 min, and the final setting time is 190 min.

[0077] The calcined clay was obtained by calcining and grinding kaolin tailings at 750℃, with a particle size range of 8 micrometers and a specific surface area of ​​1.53 m². 2 / g. The limestone powder is heavy calcium carbonate powder with a particle size range of 7 micrometers and a specific surface area of ​​2.91 m². 2 / g, calcium carbonate content 96%.

[0078] The fly ash is classified as secondary fly ash, with a particle size range of 54 micrometers and a specific surface area of ​​1.53 m². 2 / g; River sand with a particle size of 0.4mm is natural river sand; Gypsum is analytical grade dihydrate gypsum; Water-reducing agent is polycarboxylate water-reducing agent with a solid content of 22% and a water reduction rate of 40%.

[0079] The mixture consists of acrylate and styrene copolymer powder in a mass ratio of 1:1.2.

[0080] The production steps include:

[0081] Step (1): Mix silicate cement, calcined clay, limestone powder and gypsum at a stirring speed of 95 prm / min for 2 min to obtain a powder mixture. Add fly ash and river sand to the powder mixture and mix at a stirring speed of 95 prm / min for 3 min to obtain mixture I.

[0082] Step (2): Mix the water-reducing agent, triethanolamine and water, and add them evenly to mixture I at a stirring speed of 100 prm / min. Stir at a speed of 170 prm / min for 3 minutes to obtain mixture II.

[0083] Step (3): Under stirring at a speed of 95 prm, add modified polymer fiber and latex powder evenly to mixture II, stir at a speed of 165 prm / min for 2 min to obtain mixture III;

[0084] Step (4): Transfer the mixture III into the mold, vibrate for 1.5 min, smooth and shape, and demold and cure after 23 h to obtain a high ductility low carbon cement-based material.

[0085] Comparative Example 1

[0086] The difference between Comparative Example 1 and Example 1 is that "PI42.5 type silicate cement" was replaced with "PI32.5 type silicate cement". Other raw materials and preparation methods are the same as in Example 1.

[0087] A high-ductility, low-carbon cement-based material and its preparation method, wherein the raw materials comprise the following parts by weight:

[0088] The ingredients are: 50 parts of PI32.5 type silicate cement, 32 parts of calcined clay, 16 parts of limestone powder, 60 parts of fly ash, 56 parts of river sand, 2 parts of gypsum, 1 part of water-reducing agent, 3 parts of modified polyvinyl alcohol fiber prepared in Preparation Example 1, 1.0 part of latex powder, 0.2 parts of triethanolamine, and 48 parts of water.

[0089] The manufacturer of PI32.5 type silicate cement is Shandong Shanlu Environmental New Materials Co., Ltd.

[0090] Comparative Example 2

[0091] The difference between Comparative Example 2 and Example 1 is that "50 parts of P1.42.5 type silicate cement" was replaced with "25 parts of PI32.5 type silicate cement and 25 parts of PI42.5 type silicate cement", and the raw material components latex powder and triethanolamine were removed. Other raw materials and preparation methods are the same as in Example 1.

[0092] A high-ductility, low-carbon cement-based material and its preparation method, wherein the raw materials comprise the following parts by weight:

[0093] 50 parts silicate cement, 32 parts calcined clay, 16 parts limestone powder, 60 parts fly ash, 56 parts river sand, 2 parts gypsum, 1 part water-reducing agent, 3 parts modified polyvinyl alcohol fiber prepared in Preparation Example 1, 1.0 part latex powder, 0.2 parts triethanolamine, and 48 parts water.

[0094] The silicate cement includes 25 parts of PI32.5 type silicate cement and 25 parts of PI42.5 type silicate cement. The manufacturer of the PI32.5 type silicate cement is Shandong Shanlv Environmental New Materials Co., Ltd.

[0095] Comparative Example 3

[0096] The difference between Comparative Example 3 and Example 1 is that the modified polyvinyl alcohol fiber was replaced with unmodified polyvinyl alcohol fiber. The manufacturer of the polyvinyl alcohol fiber was Shandong Jinhongyao Engineering Materials Co., Ltd., and the other raw materials and manufacturing methods were the same as in Example 1.

[0097] A high-ductility, low-carbon cement-based material and its preparation method, wherein the raw materials comprise the following parts by weight:

[0098] 50 parts silicate cement, 32 parts calcined clay, 16 parts limestone powder, 60 parts fly ash, 56 parts river sand, 2 parts gypsum, 1 part water-reducing agent, 3 parts polyvinyl alcohol fiber, 1.0 part latex powder, 0.2 parts triethanolamine, and 48 parts water.

[0099] test

[0100] The characterization methods and test specimen dimensions described in the following embodiments are as follows:

[0101] Uniaxial stress-strain curves were obtained through uniaxial tensile tests. The test specimens used were dog-bone type specimens recommended by the Japan Society of Civil Engineers. The gauge length of the test specimens was 80 mm in length, 30 mm in width, and 13 mm in thickness.

[0102] The ion penetration resistance test was conducted using the electrical flux method in the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GBT50082-2009). Cylindrical specimens with a diameter of 100 mm and a height of 50 mm were used, and the electrical flux values ​​were measured at 28 days and 56 days. The drying shrinkage strain test method referred to JC / T 603-2004 "Test Method for Drying Shrinkage of Cement Mortar," using prisms with dimensions of 25 mm × 25 mm × 280 mm. A planetary mixer was used in this invention.

[0103] The cement-based materials prepared by the methods in Examples 1-3 showed higher compressive strength on days 7 and 28 than those in Comparative Examples 1-3, and improved ultimate tensile strength and tensile strain capacity. The silicate cement prepared by the methods in Examples 1-3 shortened the initial setting time and final setting time, while reducing the electrical flux on days 28 and 56 and increasing the drying shrinkage values ​​on days 28, 56 and 90 (Tables 1 and 2).

[0104] Table 1

[0105]

[0106] Table 2

[0107] Components 28-day shrinkage value 56-day shrinkage value 90d shrinkage value Example 1 1238 1335 1393 Example 2 1254 1332 1381 Example 3 1244 1339 1398 Comparative Example 1 1180 1262 1275 Comparative Example 2 1106 1212 1228 Comparative Example 3 1138 1235 1293

[0108] Experimental Results: This invention utilizes a combination of raw materials including silicate cement, calcined clay, limestone powder, fly ash, modified polyvinyl alcohol fiber, 0.6 parts of latex powder, and triethanolamine. The modified polyvinyl alcohol fiber is prepared using water-soluble polyvinyl alcohol, diethylene glycol dibenzoate, epoxy-modified silicone oil, rubber powder, penetrant, and water, followed by hot rolling reinforcement and two-stage adhesive application. The cement-based materials prepared according to the methods of Examples 1-3 of this invention effectively improve flexural and compressive strength. The compressive strength of the cement-based materials prepared by the methods of Examples 1-3 is higher than that of Comparative Examples 1-3 at both day 7 and day 28, and their ultimate tensile strength and tensile strain capacity are improved, setting time is shortened, electrical flux is reduced at days 28 and 56, and drying shrinkage values ​​at days 28, 56, and 90 are increased. When the raw materials in Comparative Examples 1-3 are changed to ordinary silicate cement and ordinary polyvinyl alcohol fiber, the flexural and compressive strength decreases, while the electrical flux increases. Therefore, the cement-based materials prepared by the raw materials, raw material ratios, and preparation methods of this invention have high setting efficiency and good application effects in terms of flexural and compressive strength.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-carbon, high-ductility cement-based material for marine engineering, characterized in that, By weight, it consists of the following components: 25-100 parts silicate cement, 10-60 parts calcined clay, 5-30 parts limestone powder, 60-110 parts fly ash, 55-100 parts river sand, 1-3 parts gypsum, 1-2 parts water-reducing agent, 2-3 parts modified polyvinyl alcohol fiber, 0.5-1.0 parts latex powder, 0.1-0.3 parts triethanolamine, and 45-100 parts water; The silicate cement is PI42.5 type silicate cement; The calcined clay is obtained by calcining and grinding kaolin tailings at 750-800℃, with a particle size range of 0.1-30 micrometers and a specific surface area of ​​1.51-1.53 ​​m². 2 / g; The preparation method of modified polyvinyl alcohol fiber includes the following steps: S1. Surface modification of PVA fibers by spraying adhesive: water-soluble polyvinyl alcohol, diethylene glycol dibenzoate, epoxy modified silicone oil, rubber powder, penetrant and water are mixed, stirred, heated, kept at a constant temperature to homogenize, and cooled to room temperature to obtain the initial adhesive solution. The mass ratio of the water-soluble polyvinyl alcohol, diethylene glycol dibenzoate, epoxy-modified silicone oil, rubber powder, penetrant, and water is 90-110:30-50:8-10:5-8:0.3-0.6:450-500. S2. Apply the initial adhesive solution to the PVA fiber to obtain a nonwoven fabric. Dry the nonwoven fabric, heat-roll it, fix it, calender it, cool it, and wind it up to obtain modified polyvinyl alcohol fiber with a fineness of 15-20 tex.

2. The marine low-carbon, high-ductility cement-based material according to claim 1, characterized in that, The epoxy-modified silicone oil is prepared by mixing vinylepoxycyclohexane and low-hydrogen silicone oil, using toluene as a solvent, and heating. The low-hydrogen silicone oil has an active hydrogen molar fraction of 0.06%-0.07% and a viscosity of 800-900 mPa·s. The vinylepoxycyclohexane and toluene are of analytical grade. The heating is carried out under nitrogen protection at a temperature of 80-85℃ for 6-8 hours.

3. The marine low-carbon, high-ductility cement-based material according to claim 1, characterized in that, The water-soluble polyvinyl alcohol has a degree of alcoholysis of 90%-99% and a degree of polymerization of 1000-1500. The penetrant is one of penetrant JFC-1, penetrant JFC-2, or penetrant JFC-E.

4. The marine engineering low-carbon high-ductility cement-based material according to claim 1, characterized in that, S1, the stirring rate is 200-220 rpm, the heating temperature is 95-100℃, and the heating time is 1.5-2h; the heat preservation and homogenization temperature is 80-85℃, and the time is 1.0-1.5h; S2, the nonwoven fabric preparation method is dry nonwoven fabric preparation, the drying temperature is 40-55℃, the hot rolling temperature is 180-200℃, the spinning speed is 700-900m / min, and the cooling method is annular blowing, the blowing temperature is 10-20℃, and the annular blowing speed is 0.2-10m / min.

5. The marine low-carbon, high-ductility cement-based material according to claim 1, characterized in that, The silicate cement has the following mineral composition by mass percentage: C2S 18%-25%, C3S 55%-60%, C4AF 8.5%-10%, and C3A 5.5%-8%. The initial setting time of the silicate cement is 115-125 min, the final setting time is 180-190 min, the 3-day compressive strength is >17.0 MPa, the 3-day flexural strength is >3.5 MPa, the 28-day compressive strength is >42.5 MPa, and the 28-day flexural strength is >6.5 MPa.

6. The marine low-carbon, high-ductility cement-based material according to claim 1, characterized in that, The limestone powder is heavy calcium carbonate powder, with a particle size range of 0.3-30 micrometers and a specific surface area of ​​2.90-2.92 m². 2 / g, calcium carbonate content >95%.

7. The marine low-carbon, high-ductility cement-based material according to claim 1, characterized in that, The fly ash is secondary fly ash with a particle size range of 0.3-200 micrometers; the river sand has a particle size of 0.1-0.6 mm and is natural river sand; the gypsum is analytical grade dihydrate gypsum; and the water-reducing agent is polycarboxylate water-reducing agent with a solid content of 18%-22% and a water reduction rate of 35%-40%.

8. The marine low-carbon, high-ductility cement-based material according to claim 1, characterized in that, The latex powder is a mixture of vinyl acetate and ethylene copolymer powder in a mass ratio of 1:1.1-1.3, or a mixture of acrylate and styrene copolymer powder in a mass ratio of 1:1.2-1.

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9. The method for preparing a marine low-carbon, high-ductility cement-based material according to claim 1, characterized in that, The production steps include the following: S1. Mix silicate cement, calcined clay, limestone powder and gypsum at a stirring speed of 90-100 prm / min for 2-3 minutes to obtain a powder mixture; add fly ash and river sand to the powder mixture and mix at a stirring speed of 90-100 prm / min for 2-3 minutes to obtain mixture I. S2. Mix the water-reducing agent, triethanolamine and water, and add the mixture evenly to mixture I at a stirring speed of 90-100 prm / min. Stir at a speed of 160-170 prm / min for 2-3 minutes to obtain mixture II. S3. Under stirring at a speed of 90-100 prm, add the modified polymer fiber and latex powder evenly to mixture II, and stir at a speed of 160-170 prm / min for 2-3 minutes to obtain mixture III; S4. Transfer the mixture III into the mold, vibrate for 1-2 minutes, smooth and shape, and demold and cure after 22-24 hours to obtain a high-ductility low-carbon cement-based material.

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