A high-strength early-strength cement-based composite material and preparation method thereof

Abstract

The present invention provides a high-strength, early-strength cement-based composite material and a preparation method thereof. The high-strength, early-strength cement-based composite material comprises the following components by weight: 400-450 parts of ordinary Portland cement, 20-25 parts of silica fume, 7-12 parts of modified polypropylene fiber, 80-90 parts of water-based epoxy resin emulsion, 1-3 parts of modified nanomaterials, 10-12 parts of polyamine curing agent, 530-580 parts of quartz sand, 5-12 parts of hydroxypropyl methylcellulose, 60-80 parts of fast-hardening agent, 4-7 parts of water-reducing agent, and 1-3 parts of defoaming agent. The high-strength, early-strength cement-based composite material prepared by the present invention has excellent mechanical strength, good impermeability, and high early strength.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete, and particularly relates to a high-strength early-strength cement-based composite material and a preparation method thereof. Background Art

[0002] Concrete is an artificial stone material widely used in construction and civil engineering. It consists of a mixture of cement, fine aggregate (usually sand), coarse aggregate (such as crushed stone or pebbles), and water in a specific proportion. Additives such as water reducers, retarders, and early strength agents are sometimes added to improve the concrete's properties.

[0003] Concrete is widely used underwater, particularly in marine engineering, hydraulic engineering, and bridge construction. When used underwater, concrete requires high early strength to facilitate rebar grouting, while also requiring a high impermeability rating and high strength to enhance its durability.

[0004] In the prior art, the following methods are generally adopted to improve the early strength of concrete: (1) using Portland cement as the main cementing material and adding other admixtures and mineral admixtures for modification, but its early strength is low and its volume shrinkage is large in the later period; (2) using sulphoaluminate mineral cement and aluminate mineral cement as cementing materials, but the production cost is high and the strength in the later period will decrease; (3) compounding Portland cement and sulphoaluminate mineral cement and adding other admixtures for modification, but the raw material composition is complex, the ratio needs to be adjusted frequently, and the applicability is poor. None of the above methods can meet the needs of the current market.

[0005] Therefore, there is an urgent need for a high-strength, early-strength cement-based composite material and a preparation method thereof. Summary of the Invention

[0006] The purpose of the present invention is to provide a high-strength early-strength cement-based composite material and a preparation method thereof.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A high-strength, early-strength cement-based composite material comprises the following components in parts by weight: 400-450 parts of ordinary Portland cement, 20-25 parts of silica fume, 7-12 parts of modified polypropylene fiber, 80-90 parts of waterborne epoxy resin emulsion, 1-3 parts of modified nanomaterial, 10-12 parts of polyamine curing agent, 530-580 parts of quartz sand, 5-12 parts of hydroxypropyl methylcellulose, 60-80 parts of accelerating agent, 4-7 parts of water reducing agent, and 1-3 parts of defoaming agent.

[0009] The preparation method of modified polypropylene fiber comprises the following steps:

[0010] (1) 90 parts by weight of polypropylene, 5-7 parts by weight of titanium dioxide, and 4-6 parts by weight of 3-isocyanatepropyltrimethoxysilane (CAS: 15396-00-6) were mixed uniformly, and the mixture was mixed and extruded into pellets through a twin-screw extruder at an extrusion temperature of 180-185° C. to obtain a modified polypropylene masterbatch;

[0011] (2) The modified polypropylene masterbatch is melt-spun to obtain modified polypropylene fibers.

[0012] Furthermore, the melt spinning conditions are: screw temperature 220-230°C, metering pump specification 0.4-0.6mL / r, metering pump speed 22-25r / min, spinneret aperture 0.4-0.6mm, number of holes 17-19, winding speed 230-250m / min, and the filament bundle is subjected to 4-5 times hot drawing after winding.

[0013] Furthermore, the polypropylene comprises polypropylene No. 1, polypropylene No. 2 and polypropylene No. 3 in a weight ratio of 1: (1.3-1.5): (0.6-0.8); the melt index of the polypropylene No. 1 is 28 g / 10 min at 2.16 kg and 230 ° C, and the tensile strength at yield is 180 kg / cm 2 , flexural modulus 9000kg / cm 2 Model: PP Korea SKBH3820; The melt index of the No. 2 polypropylene is 45g / 10min at 2.16kg and 230°C, and the tensile strength at yield is 300kg / cm 2 , flexural modulus 12000kg / cm 2 Model: PP Korea SKR390Y; The melt index of the No. 3 polypropylene is 40g / 10min at 2.16kg and 230℃, and the tensile strength at yield is 270kg / cm 2 , flexural modulus 13000kg / cm 2 Model: PP Korean SK B391G. Purchased from Shanghai Langte Import and Export Co., Ltd.

[0014] The present invention attempts to add polypropylene fibers to the system to improve the compressive strength of cement-based composite materials, but the effect is not ideal. The present invention has a good improvement effect on the 28d compressive strength of cement-based composite materials by preparing modified polypropylene fibers. Analysis shows that the modified polypropylene fibers are grafted with amphiphilic titanium dioxide, which makes the modified polypropylene fibers more dispersible in the system and more compatible with other components of the system. It can form a complex network structure during the hardening process of the cement-based composite material, and can strengthen the interface transition zone between cement paste and coarse aggregate in concrete, thereby improving the overall bearing capacity and improving the compressive strength of the cement-based composite material.

[0015] Furthermore, the preparation method of the modified nanomaterial comprises the following steps:

[0016] (1) 10 parts by weight of nanomaterial, 4-4.5 parts by weight of hexadecyltrimethylammonium bromide, 17-20 parts by weight of water and 0.10-0.15 parts by weight of NaCl, adjusting the pH value of the system to 8.0-8.2 with 0.1 mol / L NaOH solution, placing in a ball mill, rotating at 300-350 r / min for 4-5 hours, washing, filtering, and vacuum drying to obtain a pre-modified nanomaterial;

[0017] (2) Add 5 parts by weight of the pre-modified nanomaterial to 30-35 parts by weight of a 50-55% ethanol aqueous solution, continue to add 0.7-0.9 parts by weight of polyvinyl alcohol, ball mill at 400 rpm for 4-5 hours, wash, filter, and dry to obtain the modified nanomaterial.

[0018] Furthermore, the nanomaterial is a mixture of carbon nanotubes, nano silicon dioxide and nano cerium oxide in a weight ratio of 1: (1.2-1.4): (0.5-0.7).

[0019] Furthermore, the carbon nanotubes have a diameter of 1-2 nm, a length of 1-3 μm, and a specific surface area of ​​420 m 2 / g; the particle size of nano-silicon dioxide is 10-15nm, and the specific surface area is 250m 2 / g; the particle size of nano-cerium oxide is 20-30nm, and the specific surface area is 15m 2 / g.

[0020] Nanomaterials tend to agglomerate, making them ineffective in systems. The present invention improves the impermeability of cement-based composites by modifying the nanomaterials. The modified nanofillers are more dispersible in the system, improving their compatibility with the cement matrix and promoting better interfacial bonding. The carbon nanotubes, nanosilica, and nanocerium oxide can fill the micropores and microscopic defects of concrete, reducing porosity and the likelihood of water penetration, thereby improving the density of the concrete.

[0021] Furthermore, the water-based epoxy resin emulsion includes water-based epoxy resin No. 1, water-based epoxy resin No. 2 and water-based epoxy resin No. 3 in a weight ratio of 1: (1.2-1.4): (0.5-0.8); wherein, the epoxy equivalent of water-based epoxy resin No. 1 is 183-190 g / eq, and the viscosity is 10000-14000 mPa.s / 25°C; the epoxy equivalent of water-based epoxy resin No. 2 is 175-185 g / eq, and the viscosity is 8000-11000 mPa.s / 25°C; the epoxy equivalent of water-based epoxy resin No. 3 is 320-360 g / eq, and the viscosity is 100-5000 cps / 25°C.

[0022] The present invention can improve the flexural tensile strength of cement-based composite materials by adding water-based epoxy resin. And when using water-based epoxy resin with specific parameters and polypropylene with specific parameters, the freeze-thaw resistance of cement-based composite materials can be improved. Analysis shows that water-based epoxy resin can form a continuous film inside concrete, sealing tiny pores and cracks, and polypropylene fiber can form a three-dimensional network structure in concrete, effectively inhibiting the development of microcracks. The two work synergistically, thereby reducing the expansion of cracks caused by freeze-thaw cycles. The sealing effect of the epoxy resin with specific parameters and the modified polypropylene fiber prepared from the polypropylene with specific parameters can provide dual protection. Both have better crack suppression effects and significantly improve the freeze-thaw resistance of concrete. When concrete shrinks and expands during freeze-thaw cycles, the fibers can bridge cracks to prevent them from further expansion. At the same time, the slump of the cement-based composite material is improved.

[0023] In order to improve the 2h compressive strength, the quick-hardening agent further includes the following components in parts by weight: 20-30 parts of calcium sulfoaluminate, 36-43 parts of anhydrous gypsum and 10-15 parts of light-burned magnesium oxide.

[0024] Furthermore, the polyamine curing agent is selected from hydroxyethyldiethylenetriamine or bishydroxyethyldiethylenetriamine.

[0025] Furthermore, the polycarboxylate water-reducing agent is an early-strength polycarboxylate water-reducing agent purchased from Tianjin Feilong Concrete Admixture Co., Ltd., with a water reduction rate of 29% and a water bleeding rate of 15%.

[0026] The present invention also provides a method for preparing a high-strength early-strength cement-based composite material, comprising the following steps: uniformly mixing the components, standing at 65-70° C. for 60-70 minutes, and obtaining a high-strength early-strength cement-based composite material.

[0027] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0028] 1. The present invention has a good improvement effect on the 28d compressive strength of cement-based composite materials by preparing modified polypropylene fibers.

[0029] 2. The present invention can improve the impermeability of cement-based composite materials by modifying nanomaterials.

[0030] 3. The present invention can improve the flexural tensile strength of cement-based composite materials by adding water-based epoxy resin, and also improve the slump of cement-based composite materials.

[0031] 4. When using waterborne epoxy resin with specific parameters and polypropylene with specific parameters, the freeze-thaw resistance of cement-based composites can be improved. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0033] The raw materials used in the following examples of the present invention are all commercially available commodities:

[0034] Hydroxypropyl methylcellulose was purchased from Jinzhou Honghai Cellulose Co., Ltd. The 2% aqueous solution has a viscosity of 42-56 dyn / cm; a viscosity of 200-200,000; and a 100 mesh pass rate of greater than 98.5%.

[0035] Ordinary Portland cement is ordinary Portland cement P.O22.5.

[0036] Silica fume, Gansu Lixinyuan Microsilica Fume Co., Ltd.

[0037] Quartz sand, Dongguan Liaobu Better Abrasive Materials Business Department, specifications 100-200 mesh.

[0038] Defoaming agent, Foshan Nanhai Datian Chemical Co., Ltd., model: AS01.

[0039] The particle size of titanium dioxide is 50-70nm and the specific surface area is 20-30m 2 / g.

[0040] Polyvinyl alcohol with a molecular weight of 30,000-45,000 was purchased from Henan Shoujie Chemical Products Co., Ltd.

[0041] The carbon nanotubes have a diameter of 1-2 nm, a length of 1-3 μm, and a specific surface area of ​​420 m 2 / g. Purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.

[0042] The particle size of nano-silicon dioxide is 10-15nm and the specific surface area is 250m 2 / g, purchased from Beijing Dekedao Gold Technology Co., Ltd.

[0043] The particle size of nano-cerium oxide is 20-30nm and the specific surface area is 15m 2 / g, purchased from Beijing Dekedao Gold Technology Co., Ltd.

[0044] Example 1

[0045] This embodiment provides a high-strength, early-strength cement-based composite material, comprising the following components in parts by weight: 420 parts of ordinary Portland cement, 23 parts of silica fume, 10 parts of modified polypropylene fiber, 85 parts of water-based epoxy resin emulsion, 2 parts of modified nanomaterials, 11 parts of polyamine curing agent, 55 parts of quartz sand, 9 parts of hydroxypropyl methylcellulose, 70 parts of fast-hardening agent, 6 parts of water reducer and 2 parts of defoaming agent.

[0046] The quick-hardening agent comprises the following components in parts by weight: 25 parts of calcium sulfoaluminate, 40 parts of anhydrous gypsum and 12 parts of light-burned magnesium oxide.

[0047] The polyamine curing agent is hydroxyethyldiethylenetriamine.

[0048] The water reducer is an early-strength polycarboxylate water reducer purchased from Tianjin Feilong Concrete Admixture Co., Ltd., with a water reduction rate of 29% and a water bleeding rate of 15%.

[0049] The preparation method of modified polypropylene fiber comprises the following steps:

[0050] (1) 90 parts by weight of polypropylene, 6 parts by weight of titanium dioxide, and 5 parts by weight of 3-isocyanate propyltrimethoxysilane were uniformly mixed, and the mixture was mixed and extruded into granules through a twin-screw extruder at an extrusion temperature of 182° C. to obtain a modified polypropylene masterbatch;

[0051] (2) The modified polypropylene masterbatch was melt-spun under the following conditions: screw temperature 225°C, metering pump specification 0.5 mL / r, metering pump speed 24 r / min, spinneret hole diameter 0.5 mm, number of holes 18, winding speed 240 m / min, and the filament bundle was subjected to 4 times heat drawing after winding to obtain modified polypropylene fiber.

[0052] The polypropylene comprises No. 1 polypropylene, No. 2 polypropylene and No. 3 polypropylene in a weight ratio of 1:1.4:0.7; the melt index of No. 1 polypropylene is 28g / 10min under the conditions of 2.16kg and 230℃, and the tensile strength at yield is 180kg / cm 2 , flexural modulus 9000kg / cm 2 Model: PP Korea SKBH3820; The melt index of the No. 2 polypropylene is 45g / 10min at 2.16kg and 230°C, and the tensile strength at yield is 300kg / cm 2, flexural modulus 12000kg / cm 2 Model: PP Korea SKR390Y; The melt index of the No. 3 polypropylene is 40g / 10min at 2.16kg and 230℃, and the tensile strength at yield is 270kg / cm 2 , flexural modulus 13000kg / cm 2 Model: PP Korean SK B391G. Purchased from Shanghai Langte Import and Export Co., Ltd.

[0053] The preparation method of the modified nanomaterial comprises the following steps:

[0054] (1) 10 parts by weight of nanomaterial, 4.2 parts by weight of hexadecyltrimethylammonium bromide, 19 parts by weight of water and 0.12 parts by weight of NaCl were added, the pH value of the system was adjusted to 8.1 with 0.1 mol / L NaOH solution, and the mixture was placed in a ball mill and milled at a speed of 320 r / min for 4.5 hours, washed, filtered and vacuum dried to obtain a pre-modified nanomaterial; the nanomaterial was a mixture of carbon nanotubes, nanosilica and nanocerium oxide in a weight ratio of 1:1.3:0.6. The carbon nanotubes had a diameter of 1-2 nm, a length of 1-3 μm and a specific surface area of ​​420 m 2 / g; the particle size of nano-silicon dioxide is 10-15nm, and the specific surface area is 250m 2 / g; the particle size of nano-cerium oxide is 20-30nm, and the specific surface area is 15m 2 / g.

[0055] (2) 5 parts by weight of the pre-modified nanomaterial was added to 32 parts by weight of a 52% ethanol aqueous solution, and 0.8 parts by weight of polyvinyl alcohol was added. The mixture was ball-milled at 400 rpm for 4.5 h, washed, filtered, and dried to obtain the modified nanomaterial.

[0056] The water-based epoxy resin emulsion includes water-based epoxy resin No. 1, water-based epoxy resin No. 2 and water-based epoxy resin No. 3 in a weight ratio of 1:1.3:0.7; the epoxy equivalent of water-based epoxy resin No. 1 is 183-190 g / eq, and the viscosity is 10,000-14,000 mPa.s / 25°C; brand: Nantong Xingchen, model: epoxy resin 0164. The epoxy equivalent of water-based epoxy resin No. 2 is 175-185 g / eq, and the viscosity is 8,000-11,000 mPa.s / 25°C; brand: Nantong Xingchen; model: epoxy resin 0161. The epoxy equivalent of water-based epoxy resin No. 3 is 320-360 g / eq, and the viscosity is 100-5,000 cps / 25°C; brand: Jiangsu Kumho, model: KWER834-57.

[0057] The preparation method of the high-strength and early-strength cement-based composite material comprises the following steps: mixing the components uniformly, and standing at 68° C. for 65 minutes to obtain the high-strength and early-strength cement-based composite material.

[0058] Example 2

[0059] This embodiment provides a high-strength, early-strength cement-based composite material, comprising the following components in parts by weight: 400 parts of ordinary Portland cement, 25 parts of silica fume, 7 parts of modified polypropylene fiber, 90 parts of water-based epoxy resin emulsion, 1 part of modified nanomaterial, 12 parts of polyamine curing agent, 530 parts of quartz sand, 12 parts of hydroxypropyl methylcellulose, 60 parts of fast-hardening agent, 7 parts of water reducer and 1 part of defoaming agent.

[0060] The quick-hardening agent comprises the following components in parts by weight: 20 parts of calcium sulfoaluminate, 43 parts of anhydrous gypsum and 10 parts of light-burned magnesium oxide.

[0061] The polyamine curing agent is bishydroxyethyldiethylenetriamine.

[0062] The water reducer is an early-strength polycarboxylate water reducer purchased from Tianjin Feilong Concrete Admixture Co., Ltd., with a water reduction rate of 29% and a water bleeding rate of 15%.

[0063] The preparation method of modified polypropylene fiber comprises the following steps:

[0064] (1) 90 parts by weight of polypropylene, 7 parts by weight of titanium dioxide, and 4 parts by weight of 3-isocyanate propyltrimethoxysilane were uniformly mixed, and the mixture was mixed and extruded into granules through a twin-screw extruder at an extrusion temperature of 185° C. to obtain a modified polypropylene masterbatch;

[0065] (2) The modified polypropylene masterbatch was melt-spun under the following conditions: screw temperature 220°C, metering pump specification 0.6 mL / r, metering pump speed 22 r / min, spinneret hole diameter 0.6 mm, number of holes 17, winding speed 250 m / min, and after winding, the filament bundle was subjected to 5 times heat drawing to obtain modified polypropylene fiber.

[0066] The polypropylene comprises No. 1 polypropylene, No. 2 polypropylene and No. 3 polypropylene in a weight ratio of 1:1.3:0.8; the melt index of No. 1 polypropylene is 28g / 10min under the conditions of 2.16kg and 230℃, and the tensile strength at yield is 180kg / cm 2 , flexural modulus 9000kg / cm 2 Model: PP Korea SKBH3820; The melt index of the No. 2 polypropylene is 45g / 10min at 2.16kg and 230°C, and the tensile strength at yield is 300kg / cm 2 , flexural modulus 12000kg / cm 2Model: PP Korea SKR390Y; The melt index of the No. 3 polypropylene is 40g / 10min at 2.16kg and 230℃, and the tensile strength at yield is 270kg / cm 2 , flexural modulus 13000kg / cm 2 Model: PP Korean SK B391G. Purchased from Shanghai Langte Import and Export Co., Ltd.

[0067] The preparation method of the modified nanomaterial comprises the following steps:

[0068] (1) 10 parts by weight of nanomaterial, 4 parts by weight of hexadecyltrimethylammonium bromide, 20 parts by weight of water and 0.10 parts by weight of NaCl were added, the pH value of the system was adjusted to 8.2 with 0.1 mol / L NaOH solution, and the mixture was placed in a ball mill at a speed of 300 r / min for 5 hours, washed, filtered and vacuum dried to obtain a pre-modified nanomaterial; the nanomaterial was a mixture of carbon nanotubes, nanosilica and nanocerium oxide in a weight ratio of 1:1.2:0.7. The diameter of the carbon nanotubes was 1-2 nm, the length was 1-3 μm, and the specific surface area was 420 m 2 / g; the particle size of nano-silicon dioxide is 10-15nm, and the specific surface area is 250m 2 / g; the particle size of nano-cerium oxide is 20-30nm, and the specific surface area is 15m 2 / g.

[0069] (2) 5 parts by weight of the pre-modified nanomaterial was added to 30 parts by weight of a 55% ethanol aqueous solution, and 0.7 parts by weight of polyvinyl alcohol was added, and the mixture was ball-milled at 400 rpm for 5 h, washed, filtered, and dried to obtain the modified nanomaterial.

[0070] The water-based epoxy resin emulsion includes water-based epoxy resin No. 1, water-based epoxy resin No. 2 and water-based epoxy resin No. 3 in a weight ratio of 1:1.2:0.8; the epoxy equivalent of water-based epoxy resin No. 1 is 183-190 g / eq, and the viscosity is 10,000-14,000 mPa.s / 25°C; brand: Nantong Xingchen, model: epoxy resin 0164. The epoxy equivalent of water-based epoxy resin No. 2 is 175-185 g / eq, and the viscosity is 8,000-11,000 mPa.s / 25°C; brand: Nantong Xingchen; model: epoxy resin 0161. The epoxy equivalent of water-based epoxy resin No. 3 is 320-360 g / eq, and the viscosity is 100-5,000 cps / 25°C; brand: Jiangsu Kumho, model: KWER834-57.

[0071] The preparation method of the high-strength and early-strength cement-based composite material comprises the following steps: uniformly mixing the components, and standing at 65° C. for 70 minutes to obtain the high-strength and early-strength cement-based composite material.

[0072] Comparative Example 1

[0073] The difference between this comparative example and Example 1 is: a high-strength, early-strength cement-based composite material, comprising the following components in parts by weight: 420 parts of ordinary Portland cement, 23 parts of silica fume, 15 parts of modified polypropylene fiber, 77 parts of water-based epoxy resin emulsion, 5 parts of modified nanomaterials, 11 parts of polyamine curing agent, 55 parts of quartz sand, 9 parts of hydroxypropyl methylcellulose, 70 parts of fast-hardening agent, 6 parts of water reducer and 2 parts of defoaming agent.

[0074] Comparative Example 2

[0075] The difference between this comparative example and Example 1 is that the polypropylene comprises No. 1 polypropylene, No. 2 polypropylene and No. 3 polypropylene in a weight ratio of 1:1:1; the melt index of No. 1 polypropylene is 28g / 10min under the conditions of 2.16kg and 230℃, and the tensile strength at yield is 180kg / cm 2 , flexural modulus 9000kg / cm 2 Model: PP Korea SKBH3820; The melt index of the No. 2 polypropylene is 45g / 10min at 2.16kg and 230°C, and the tensile strength at yield is 300kg / cm 2 , flexural modulus 12000kg / cm 2 Model: PP Korea SKR390Y; The melt index of the No. 3 polypropylene is 60g / 10min at 2.16kg and 230℃, and the tensile strength at yield is 180kg / cm 2 , flexural modulus 8500kg / cm 2 Model: PP Korean SKBH3820. Purchased from Shanghai Langte Import and Export Co., Ltd.

[0076] Comparative Example 3

[0077] The difference between this comparative example and Example 1 is that the polypropylene comprises polypropylene No. 1, polypropylene No. 2 and polypropylene No. 3 in a weight ratio of 1:1.4:0.7; the melt index of polypropylene No. 1 is 6.0 g / 10 min at 2.16 kg and 230 ° C, and the tensile strength at yield is 260 kg / cm 2 , flexural modulus 10000kg / cm 2 Model: PP Korea SK R140M; The melt index of the No. 2 polypropylene is 60g / 10min at 2.16kg and 230℃, and the tensile strength at yield is 180kg / cm 2 , flexural modulus 8500kg / cm 2Model: PP Korea SK BH3910; The melt index of the No. 3 polypropylene is 60g / 10min at 3.5kg and 230℃, and the tensile strength at yield is 170kg / cm 2 , flexural modulus 12000kg / cm 2 Model: PP Korean SK B330F. Purchased from Shanghai Langte Import and Export Co., Ltd.

[0078] Comparative Example 4

[0079] The difference between this comparative example and Example 1 is that the preparation method of the modified nanomaterial comprises the following steps: adding 5 parts by weight of nanomaterial to 32 parts by weight of 52% ethanol aqueous solution, further adding 0.8 parts by weight of polyvinyl alcohol, ball milling at 400 r / min for 4.5 hours, washing, filtering, and drying to obtain the modified nanomaterial.

[0080] The nanomaterial is a mixture of carbon nanotubes, nanosilicon dioxide and nanocerium oxide in a weight ratio of 1:1.3:0.6. The carbon nanotubes have a diameter of 1-2nm, a length of 1-3μm and a specific surface area of ​​420m 2 / g; the particle size of nano-silicon dioxide is 10-15nm, and the specific surface area is 250m 2 / g; the particle size of nano-cerium oxide is 20-30nm, and the specific surface area is 15m 2 / g.

[0081] Comparative Example 5

[0082] The difference between this comparative example and Example 1 is that the nanomaterial is a mixture of carbon nanotubes, nano-silicon dioxide and nano-cerium oxide in a weight ratio of 1:1:1.

[0083] Comparative Example 6

[0084] The difference between this comparative example and Example 1 is that the aqueous epoxy resin emulsion includes aqueous epoxy resin No. 1, aqueous epoxy resin No. 2 and aqueous epoxy resin No. 3 in a weight ratio of 1:1:1; wherein, the epoxy equivalent of aqueous epoxy resin No. 1 is 183-190 g / eq, and the viscosity is 10000-14000 mPa.s / 25°C; the epoxy equivalent of aqueous epoxy resin No. 2 is 175-185 g / eq, and the viscosity is 8000-11000 mPa.s / 25°C; the epoxy equivalent of aqueous epoxy resin No. 3 is 320-360 g / eq, and the viscosity is 100-5000 cps / 25°C.

[0085] Comparative Example 7

[0086] This comparative example differs from Example 1 in that the water-based epoxy resin emulsion comprises water-based epoxy resin No. 1, water-based epoxy resin No. 2, and water-based epoxy resin No. 3 in a weight ratio of 1:1.3:0.7. Water-based epoxy resin No. 1 has an epoxy equivalent weight of 500-600 g / eq and a viscosity of 1000-6000 mPa·s at 25°C. Brand: Hexam Momentive, USA, Model: Epikote 6520-WH-53A. Water-based epoxy resin No. 2 has an epoxy equivalent weight of 195-210 and a viscosity of 15,000-25,000 mPa·s at 25°C. Brand: Hexam Momentive, USA, Model: Epikote WD-52A. Water-based epoxy resin No. 3 has an epoxy equivalent weight of 191-211 g / eq and a viscosity of 1000-7000 mPa·s at 25°C. Brand: Shanghai Kaiyin Chemical Co., Ltd., Model: Water-based epoxy resin KWER834-57.

[0087] Performance Testing

[0088] The cement-based composite materials prepared in Examples 1-2 and Comparative Examples 1-7 were used as samples for performance testing:

[0089] Determine slump according to GB / T50080-2016;

[0090] Referring to GB / T50081-2019, the cement-based composite materials were cured at a curing temperature of 25±2°C and a relative humidity of 90±5%. The compressive strength at each age was measured, and the tensile and flexural strength as well as the freeze-thaw resistance were tested after 28 days of curing.

[0091] Impermeability: Refer to GB / T50082-2009 to measure the maximum hydrostatic pressure at which the sample does not seep water.

[0092] The results are shown in Table 1.

[0093] Table 1 Performance test results

[0094]

[0095]

[0096] From the above performance test results, it can be seen that Examples 1-2 have excellent comprehensive performance, especially Example 1 has the most outstanding comprehensive performance, which is mainly due to the synergistic combination of multiple components.

[0097] The comparative examples, however, did not adopt the necessary technical solutions, resulting in significantly worse performance tests than the examples. In comparative example 1, the ratios of modified polypropylene fiber, water-based epoxy resin emulsion, and modified nanomaterials were changed, and it was found that the performance of the samples decreased to varying degrees, indicating that these three components work synergistically in the system to improve the performance of the composite material. In comparative example 2, the polypropylene ratio was different, and the 28d compressive strength of the cement-based composite decreased; in comparative example 3, the parameters of the polypropylene were different, and the results showed that the freeze-thaw resistance effect decreased. In comparative example 4, the preparation method of the modified nanomaterial was different, and the impermeability decreased. Analysis showed that the nanomaterial was not pretreated, resulting in uneven reaction with polyvinyl alcohol and poor coating effect. In comparative example 5, the composition of the nanomaterial was different, and the impermeability decreased, indicating that the three nanomaterials work synergistically with each other. In comparative example 6, the ratio of the water-based epoxy resin was different, and the flexural tensile strength and slump of the cement-based composite decreased. In comparative example 7, the parameters of the water-based epoxy resin were different, and the freeze-thaw resistance of the cement-based composite decreased. The above experimental results further demonstrate the importance of the technical solution defined in the present invention for its technical effects.

[0098] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A high-strength early-strength cement-based composite material, characterized in that: The invention comprises the following components in parts by weight: 400-450 parts of ordinary Portland cement, 20-25 parts of silica fume, 7-12 parts of modified polypropylene fiber, 80-90 parts of waterborne epoxy resin emulsion, 1-3 parts of modified nanomaterial, 10-12 parts of polyamine curing agent, 530-580 parts of quartz sand, 5-12 parts of hydroxypropyl methylcellulose, 60-80 parts of accelerating agent, 4-7 parts of water reducing agent and 1-3 parts of defoaming agent; The preparation method of modified polypropylene fiber comprises the following steps, in parts by weight: (1) 90 parts of polypropylene, 5-7 parts of titanium dioxide, and 4-6 parts of 3-isocyanate propyltrimethoxysilane are mixed uniformly, mixed and extruded into granules through a twin-screw extruder at an extrusion temperature of 180-185°C to obtain a modified polypropylene masterbatch; (2) melt spinning the modified polypropylene masterbatch to obtain modified polypropylene fiber; In parts by weight, the preparation method of the modified nanomaterial comprises: (1) 10 parts of nanomaterial, 4-4.5 parts of hexadecyltrimethylammonium bromide, 17-20 parts of water and 0.10-0.15 parts of NaCl were added, and the pH value of the system was adjusted to 8.0-8.

2. The mixture was placed in a ball mill at a speed of 300-350 r / min and ball milled for 4-5 hours. The mixture was washed, filtered and vacuum dried to obtain a pre-modified nanomaterial. (2) Add 5 parts of pre-modified nanomaterial to 30-35 parts of ethanol aqueous solution, continue to add 0.7-0.9 parts of polyvinyl alcohol, ball mill for 4-5 hours, wash, filter and dry to obtain modified nanomaterial; The nanomaterial is a mixture of carbon nanotubes, nanosilicon dioxide and nanocerium oxide in a weight ratio of 1: (1.2-1.4): (0.5-0.7); the diameter of the carbon nanotubes is 1-2nm, the length is 1-3μm, and the specific surface area is 420m 2 / g; the particle size of nano-silicon dioxide is 10-15nm, and the specific surface area is 250m 2 / g; the particle size of nano-cerium oxide is 20-30nm, and the specific surface area is 15m 2 / g; The water-based epoxy resin emulsion includes water-based epoxy resin No. 1, water-based epoxy resin No. 2 and water-based epoxy resin No. 3 in a weight ratio of 1: (1.2-1.4): (0.5-0.8); the epoxy equivalent of water-based epoxy resin No. 1 is 183-190 g / eq, and the viscosity is 10000-14000 mPa.s / 25°C; the epoxy equivalent of water-based epoxy resin No. 2 is 175-185 g / eq, and the viscosity is 8000-11000 mPa.s / 25°C; the epoxy equivalent of water-based epoxy resin No. 3 is 320-360 g / eq, and the viscosity is 100-5000 cps / 25°C.

2. The high-strength, early-strength cement-based composite material according to claim 1, characterized in that: The melt spinning conditions are: screw temperature 220-230°C, metering pump specification 0.4-0.6mL / r, metering pump speed 22-25r / min, spinneret aperture 0.4-0.6mm, number of holes 17-19, winding speed 230-250m / min, and the filament bundle is subjected to 4-5 times hot drawing after winding.

3. The high-strength, early-strength cement-based composite material according to claim 2, characterized in that: The mass percentage of ethanol in the ethanol aqueous solution is 50-55%.

4. The high-strength, early-strength cement-based composite material according to claim 3, characterized in that: The quick-hardening agent comprises the following components in parts by weight: 20-30 parts of calcium sulfoaluminate, 36-43 parts of anhydrous gypsum and 10-15 parts of light-burned magnesium oxide.

5. The high-strength, early-strength cement-based composite material according to claim 1, characterized in that: The polyamine curing agent is selected from hydroxyethyldiethylenetriamine or bishydroxyethyldiethylenetriamine.

6. A method for preparing the high-strength, early-strength cement-based composite material according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: mixing the components uniformly, and standing at 65-70 DEG C for 60-70 minutes to obtain a high-strength early-strength cement-based composite material.

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