Composition for producing a cement-based composite, cement-based composite, method for producing the same, and use thereof

Abstract

The present application relates to the technical field of cement-based composite material, and discloses a composition for preparing a cement-based composite material, the cement-based composite material, a preparation method and application thereof, wherein the composition contains cement, sand, fly ash, silica fume, a high-efficiency water reducing agent, a thickening agent, water, mixed fibers, and a polymer emulsion; the mixed fibers are a combination of high-strength stainless steel fibers and polyvinyl alcohol fibers, the high-strength stainless steel fibers are formed by spirally winding at least two steel ropes, and the steel ropes are formed by spirally winding at least two steel wires.The cement-based composite material provided by the present application has excellent strength, toughness, crack resistance and durability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cement-based composite materials, in particular to a composition for preparing a cement-based composite material, the cement-based composite material, a preparation method therefor and an application thereof. BACKGROUND

[0002] At present, cement-based composite materials have been widely used in the field of building materials, but problems such as cracks, deformation, and insufficient tensile strength often occur during their application, which seriously restricts their application in actual engineering construction. Traditional modification methods mainly include adding fibers and adding admixtures, but these methods have some limitations.

[0003] Adding a certain proportion of fibers can improve the toughness and crack resistance of the material, but at the same time, it will also affect the compressive strength and elastic modulus. Adding admixtures may cause peeling and loose problems of the material. After adding a single type of fiber, only a single performance can be improved, and the comprehensive performance is difficult to meet the requirements. In order to solve these problems, researchers have begun to consider mixing different types of fibers in order to obtain better performance.

[0004] For example, CN114560656A discloses a double-scale toughened cement-based composite material and its application, which comprises a cementitious binder, a polymer monomer, an initiator, a crosslinking agent, and a fiber; the functional groups of the polymer monomer include carbon-carbon double bonds and carboxyl groups; the fiber includes steel fiber and / or synthetic fiber; the synthetic fiber includes one or more of polyvinyl alcohol fiber, polypropylene fiber, glass fiber, and carbon fiber. The prior art can improve the toughness and compressive and flexural properties of the cement-based material to a certain extent, but the prior art uses a crosslinking agent, which will have a negative impact on the environment during production or at the end of product disposal, and increases the manufacturing cost of the cement-based composite material.

[0005] CN111410476A discloses a high-performance anti-permeability concrete, which comprises the following components: coarse aggregate 1000-1200 parts, fine aggregate 550-650 parts, cement 400-500 parts, fly ash 80-120 parts, silica powder 50-65 parts, high-efficiency water reducing agent 8-10 parts, reinforcing filler 100-200 parts, and water 120-180 parts. The prior art has the technical effects of high structural strength and excellent anti-permeability performance. However, the proportion of coarse aggregate in the proportioning of the prior art is high, and the elastic modulus difference between the coarse aggregate and the cement paste is large, which is more likely to cause internal stress concentration during stress process, increasing the risk of cracks, and the coarse aggregate has the potential risk of inconsistent particle size distribution, thereby leading to a decrease in the performance of the concrete. SUMMARY

[0006] The present application aims to provide a cement-based composite material with excellent strength, toughness, crack resistance and durability.

[0007] To achieve the above-mentioned purpose, the first aspect of the present application provides a composition for preparing a cement-based composite material, which comprises cement, sand, fly ash, silica fume, superplasticizer, thickening agent, water, hybrid fiber, and polymer emulsion; the polymer emulsion is polyacrylate emulsion and / or polyvinyl ester emulsion.

[0008] The content of the sand is 35-45 parts by weight, the content of the fly ash is 280-320 parts by weight, the content of the silica fume is 7-8 parts by weight, the content of the superplasticizer is 3.5-4.5 parts by weight, the content of the thickening agent is 0.1-0.3 parts by weight, the content of the water is 97.8-115 parts by weight, and the content of the polymer emulsion is 1-3 parts by weight, relative to 100 parts by weight of the cement.

[0009] The hybrid fiber is a combination of high-strength stainless steel fiber and polyvinyl alcohol fiber, and the volume content of the hybrid fiber is 1.5-2.2% based on the total volume of the components in the composition except the hybrid fiber.

[0010] The high-strength stainless steel fiber is formed by spirally winding at least two steel ropes, and the steel rope is formed by spirally winding at least two steel wires; the average length of the high-strength stainless steel fiber is 20-60 mm, and the average diameter is 0.2-0.8 mm.

[0011] The second aspect of the present application provides a method for preparing a cement-based composite material, which uses the components in the composition of the first aspect described above, comprising:

[0012] (1) First mixing dry powder materials, polymer emulsion, part of component A, and optional nano-silicon dioxide to obtain mixture I; the dry powder materials contain sand, fly ash, and silica fume; the component A contains water, cement, and superplasticizer; the part of component A accounts for 40-60 wt% of the total component A;

[0013] (2) Second mixing the mixture I with hybrid fiber to obtain mixture II;

[0014] (3) Third mixing the mixture II with thickening agent and the remaining component A to obtain mixture III;

[0015] (4) Successively pouring and forming the mixture III, and curing to obtain the cement-based composite material.

[0016] The third aspect of the present application provides a cement-based composite material prepared by the method of the preceding second aspect.

[0017] The fourth aspect of the present application provides the use of the cement-based composite material of the preceding third aspect in building materials.

[0018] Compared with the prior art, the technical solution provided by the present application has at least the following advantages:

[0019] 1) The high-strength stainless steel fiber provided by the present application has high strength and rigidity, which can effectively enhance the tensile, compressive and other properties of the cement-based composite material, and improve its carrying capacity and durability. Moreover, the high-strength stainless steel fiber has excellent corrosion resistance, which can prolong the service life of the cement-based composite material. The polyvinyl alcohol fiber has good toughness and ductility, which can effectively improve the crack resistance and seismic performance of the composite material, and reduce the crack width and quantity of the material. The two fibers have good synergistic working ability, and the composite material in the processing process has good fluidity and plasticity, which is easier to construct and form, reduces the construction difficulty and cost, and has good comprehensive performance.

[0020] 2) The present application mixes high-strength stainless steel fiber and polyvinyl alcohol fiber, which fully utilizes the advantages of the two fibers, forms a multi-level reinforcing system in the cement-based composite material, and greatly improves the strength, toughness and durability of the cement-based composite material. It meets the requirements of green building materials and has good social, environmental and economic benefits. It has a wide application prospect in the field of engineering.

[0021] 3) The method provided by the present application is simple and easy to implement, which can greatly reduce the production cost and improve the stability and consistency of the material. DETAILED DESCRIPTION

[0022] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not considered critical for the present application. The endpoints of the ranges and any values are only approximations. The range is intended to encompass minimum and maximum values, including any values whose endpoint is not expressly recited, whether such minimum and maximum values are within a particular range. The exact dimensions are not considered critical for the present application.

[0023] It should be noted that in the aspects of the present application, for the same components or terms in the aspects, the present application is described only once in one aspect without repeated description, and the person skilled in the art should not understand it as a limitation of the present application.

[0024] The average particle size described in the present application represents the average diameter.

[0025] As described above, the first aspect of the present application provides a composition for preparing a cement-based composite material, wherein the composition comprises cement, sand, fly ash, silica fume, superplasticizer, thickening agent, water, mixed fibers, and polymer emulsion; the polymer emulsion is polyacrylate emulsion and / or polyvinyl ester emulsion;

[0026] The content of the sand is 35-45 parts by weight, the content of the fly ash is 280-320 parts by weight, the content of the silica fume is 7-8 parts by weight, the content of the superplasticizer is 3.5-4.5 parts by weight, the content of the thickening agent is 0.1-0.3 parts by weight, the content of the water is 97.8-115 parts by weight, and the content of the polymer emulsion is 1-3 parts by weight, relative to 100 parts by weight of the cement.

[0027] The mixed fibers are a combination of high-strength stainless steel fibers and polyvinyl alcohol fibers, and the volume content of the mixed fibers is 1.5-2.2% based on the total volume of the components in the composition except the mixed fibers.

[0028] The high-strength stainless steel fibers are formed by spirally winding at least two steel ropes, and the steel ropes are formed by spirally winding at least seven steel wires; the average length of the high-strength stainless steel fibers is 20-60 mm, and the average diameter is 0.2-0.8 mm.

[0029] Preferably, the average length of the high-strength stainless steel fibers is 30-50 mm, and the average diameter is 0.4-0.6 mm. The inventors of the present application have found that the cement-based composite material prepared using the high-strength stainless steel fibers under the preferred conditions has more excellent mechanical properties and durability.

[0030] Preferably, the high-strength stainless steel fibers are formed by spirally winding seven steel ropes, and the steel ropes are formed by spirally winding seven steel wires.

[0031] The average diameter of the high-strength stainless steel fibers in the present application refers to the average diameter of the circumscribed circle of the cross-sectional shape of the high-strength stainless steel fibers.

[0032] The present application does not have special limitations on the spiral winding angle of the steel ropes and steel wires of the high-strength stainless steel fibers, and those skilled in the art can select the raw materials according to the prior art, which will not be described herein again, and those skilled in the art should not understand it as a limitation of the present application.

[0033] The present application does not have special restrictions on the specific processing method of the high-strength stainless steel fiber, and those skilled in the art can select according to the technical means known in the art, and the present application exemplarily provides a preferred specific embodiment, exemplarily, a full-automatic numerical control steel wire rope cutting machine on the market is used as a cutting processing equipment to cut the raw materials meeting the present application to obtain the high-strength stainless steel fiber of the present application.

[0034] Preferably, the volume content of the hybrid fiber is 1.8-2.2% based on the total volume of each component in the composition except the hybrid fiber, and the inventors of the present application found in the research that the cement-based composite material prepared using the volume content of the hybrid fiber under the preferred condition has more excellent mechanical properties and durability.

[0035] Preferably, the volume ratio of the high-strength stainless steel fiber to the polyvinyl alcohol fiber is 1:0.5-5.

[0036] More preferably, the volume ratio of the high-strength stainless steel fiber to the polyvinyl alcohol fiber is 1:1-3. The inventors of the present application found in the research that the cement-based composite material of the present application has more excellent tensile and compressive properties and stronger durability under the preferred volume ratio condition.

[0037] Preferably, the tensile strength of the high-strength stainless steel fiber is 1-2 GPa, the elastic modulus is 100-110 GPa, and the density is 7.9-8.0 g / cm 3 .

[0038] Preferably, the average length of the polyvinyl alcohol fiber is 6-12 mm, and the average diameter is 10-25 μm.

[0039] Preferably, the tensile strength of the polyvinyl alcohol fiber is 1.0-1.6 GPa, the elastic modulus is 380-400 cN / dtex, and the density is 1.3-1.5 g / cm 3 .

[0040] The inventors of the present application found in the research that the polyvinyl alcohol fiber meeting the preferred condition of the present application and the preferred high-strength stainless steel fiber of the present application synergistically act in the cement-based composite material to greatly improve the strength, toughness and durability of the cement-based composite material.

[0041] Preferably, the composition further contains nano-silicon dioxide, and the content of the nano-silicon dioxide is 0.1-0.3 parts by weight, more preferably 0.15-0.25 parts by weight, relative to 100 parts by weight of the cement.

[0042] The nano-silicon dioxide of the present application refers to a silicon dioxide powder with an average particle size of ≤100 nm.

[0043] According to a preferred specific embodiment, the nanosilica exists in the form of a nanosilica solution, and the solid content in the nanosilica solution is 20-40 wt%.

[0044] The kind of the solvent of the nanosilica solution is not particularly limited in the present application, as long as the nanosilica can be uniformly dispersed therein, and exemplarily, the solvent is water, which is not repeated here and should not be understood as a limitation to the present application by those skilled in the art.

[0045] Preferably, the water-binder ratio of the composition is 0.24-0.28:1.

[0046] The water-binder ratio in the present application refers to the ratio of the weight of water to the total weight of cement, fly ash and silica fume.

[0047] According to another preferred specific embodiment, the solid content in the polymer emulsion is 50-60 wt%.

[0048] More preferably, the polymer emulsion is a modified polyacrylate emulsion with the trade name of MT-1068 purchased from Beijing Montai Weiyeye Building Material Co., Ltd., or the polymer emulsion is a polyvinyl ester emulsion with the trade name of VAE-707 purchased from Henan Zhenghui Chemical Co., Ltd.

[0049] Preferably, the cement is ordinary portland cement.

[0050] Preferably, the sand is quartz sand, and the average particle size of the quartz sand is 0.1-0.3 mm.

[0051] Preferably, the average particle size of the silica fume is 0.15-0.25 μm, and the SiO2 content is ≥95 wt%.

[0052] Preferably, the average particle size of the fly ash is 0.08-0.12 mm, and the density is 145-210 kg / m 3 .

[0053] Preferably, the thickening agent is bentonite and / or hydroxyethyl methyl cellulose.

[0054] Preferably, the high-efficiency water-reducing agent is a polycarboxylic acid type high-efficiency water-reducing agent.

[0055] The high-efficiency water-reducing agent is preferably diluted with water in a weight ratio of 1:3.5-4.5 before use.

[0056] In the composition for preparing the cement-based composite material provided by the present application, the water content includes the amount of water used for diluting the superplasticizer and other additional water, but does not include the water possibly present in the polymer emulsion, the nano-silica solution and the superplasticizer before being diluted.

[0057] As described above, the second aspect of the present application provides a method for preparing a cement-based composite material, which is performed by using the components in the composition of the aforementioned first aspect, and comprises:

[0058] (1) first mixing dry powder materials, the polymer emulsion, part of component A and optional nano-silica to obtain mixture I; the dry powder materials contain sand, fly ash and silica fume; the component A contains water, cement and superplasticizer; the part of component A accounts for 40-60wt% of the total component A;

[0059] (2) second mixing the mixture I with hybrid fibers to obtain mixture II;

[0060] (3) third mixing the mixture II with a thickening agent and the remaining component A to obtain mixture III;

[0061] (4) sequentially performing casting and curing treatment on the mixture III to obtain the cement-based composite material.

[0062] In step (1) of the present application, in order to ensure the uniformity of the mixture and shorten the mixing time, the present application preferably first mixes the dry powder materials uniformly before participating in the first mixing.

[0063] Preferably, in step (1), the stirring rate of the first mixing is 100-150 rpm.

[0064] According to a preferred specific embodiment, in step (2), the method further comprises: first soaking the hybrid fibers in water at 50-60℃ for 20-40 min, and then air-drying the hybrid fibers to obtain the hybrid fibers, and then second mixing the hybrid fibers with the mixture I.

[0065] The inventors of the present application found in research that when the hybrid fibers after soaking treatment are applied to the cement-based composite material, the cement-based composite material has more excellent mechanical properties and durability.

[0066] Preferably, in step (2), the stirring rate of the second mixing is 60-100 rpm.

[0067] Preferably, in step (3), the stirring rate of the third mixing is 60-100 rpm.

[0068] The present application does not have a particular limitation on the specific time of the first mixing, the second mixing and the third mixing, as long as the materials can be mixed uniformly. The present application provides a preferred specific embodiment in the following examples, which should not be construed as a limitation on the present application.

[0069] Preferably, the step of "casting and curing the mixture III in sequence to obtain the cement-based composite material" in step (4) comprises:

[0070] Step (41): pouring the mixture III into a mold and then vibrating for 1-3 min to obtain a cement block I;

[0071] Step (42): statically stopping the cement block I at a relative humidity of 80-95% and a temperature of 20-30℃ for 20-30 h, and then demolding to obtain a cement block II;

[0072] Step (43): sequentially performing film curing and room temperature curing on the cement block II to obtain the cement-based composite material; the film curing time is 2-4 d; and the room temperature curing time is 22-30 d.

[0073] The present application does not have a particular limitation on the size of the mold in step (41), which can be selected by a person skilled in the art according to actual needs. For example, the size of the mold is 100 mm x 100 mm x 400 mm, which should not be construed as a limitation on the present application.

[0074] As described above, the third aspect of the present application provides a cement-based composite material prepared by the method of the aforementioned second aspect.

[0075] The cement-based composite material provided by the present application can effectively inhibit the expansion of cracks, with a crack width of less than 0.1 mm.

[0076] Under cyclic loading, the cement-based composite material provided by the present application has better fatigue resistance and can withstand more cyclic loads without causing serious damage and performance degradation.

[0077] When subjected to impact load, the cement-based composite material provided by the present application can absorb and disperse impact energy, reducing the degree of damage to the structure. The improvement of impact toughness makes the cement-based composite material exhibit better performance under extreme working conditions such as wind resistance and earthquake resistance.

[0078] As described above, the fourth aspect of the present application provides the use of the cement-based composite material of the aforementioned third aspect in building materials.

[0079] In the present application, the polymer emulsion can form a composite structure of polymer and cement-based material, improve the strength and toughness of the material. At the same time, it can also form a protective film on the surface of the material, increase the durability of the material. With the introduction of nano-silica solution, combined with the remaining technical features of the present application, a composite structure of polymer and nano-particles and cement-based material can be formed, and the three work together to further improve the mechanical properties and durability of the material.

[0080] The cement-based composite material prepared by the technical scheme provided by the present application has significant improvement in compressive strength, tensile strength, fracture toughness and crack resistance, and is suitable for engineering applications that require higher performance materials.

[0081] The present application will be described in detail below by examples. In the following examples, a full-automatic numerical control steel wire rope cutting machine is used to cut the steel fiber raw materials;

[0082] In the following examples, the high-strength stainless steel fiber formed by 7 bundles of steel ropes spirally wound, and the steel rope formed by 7 strands of steel wire spirally wound is called 7*7 type steel fiber;

[0083] In the following examples, the high-strength stainless steel fiber formed by 3 bundles of steel ropes spirally wound, and the steel rope formed by 3 strands of steel wire spirally wound is called 3*3 type steel fiber;

[0084] In the following examples, the room temperature means 25±2℃;

[0085] In the following examples, the raw materials are all commercially available unless otherwise specified, and the specific sources of raw materials are shown in Table 1:

[0086] Table 1

[0087]

[0088] In the following examples and comparative examples, each part or each weight part means 1kg.

[0089] Example 1

[0090] (1) Put quartz sand and fly ash into a forced stirrer, stir at 100rpm for 5min, then add silica ash, stir at 100rpm for 2min, to obtain dry powder material;

[0091] (2) Mix the dry powder material with polyvinyl ester emulsion, nano-silica solution, and part of component A for the first time (100rpm, 5min) to obtain mixture I; the component A contains water, cement, and high-efficiency water reducing agent; the part of component A accounts for 50wt% of the total component A;

[0092] (3) high-strength stainless steel fibers and polyvinyl alcohol fibers were soaked in 60℃ for 30 min, dried, and then the obtained high-strength stainless steel fibers and polyvinyl alcohol fibers were second mixed with mixture I (60 rpm, 5 min) to obtain mixture II;

[0093] (4) mixture II was third mixed with thickening agent, the remaining component A (60 rpm, 5 min) to obtain mixture III;

[0094] (5) mixture III was cast into a 100 mm x 100 mm x 400 mm mold in one time, and then placed on a concrete vibrating table for 1 min of vibration; the excess mixture was scraped off with a spatula, and the mixture was demolded after 24 h of static standing in an environment with a temperature of 25℃ and a relative humidity of 90%; after 3 d of film covering, the film was removed and the cement-based composite material was cured at room temperature for 28 d.

[0095] Examples 2-4

[0096] The similar procedure of Example 1 was adopted, except that the types, amounts, and proportions of the components were different, which were listed in Table 2.

[0097] Example 5

[0098] The similar procedure of Example 1 was adopted in this example, except that high-strength stainless steel fiber I was replaced by an equal volume of high-strength stainless steel fiber II.

[0099] The cement-based composite material was prepared.

[0100] Example 6

[0101] The similar procedure of Example 1 was adopted in this example, except that polyvinyl alcohol fiber I was replaced by an equal volume of polyvinyl alcohol fiber II.

[0102] The cement-based composite material was prepared.

[0103] Example 7

[0104] The similar procedure of Example 1 was adopted in this example, except that in step (2), no nano-silica solution was added, and the remaining components and amounts were kept unchanged. Specifically:

[0105] Step (2): dry powder materials were first mixed with polyvinyl alcohol ester emulsion and part of component A (100 rpm, 5 min) to obtain mixture I; the component A contained water, cement, and high-efficiency water reducer; the part of component A accounted for 50 wt% of the total component A.

[0106] A cement-based composite material is prepared.

[0107] Example 8

[0108] This example is carried out by using a similar procedure as that of Example 1, except that in step (3), the high-strength stainless steel fiber and polypropylene fiber used in this example are not subjected to soaking treatment, and are directly mixed with mixture I for the second time, and the rest of the process conditions, the types and amounts of the components remain unchanged. Specifically:

[0109] Step (3): The high-strength stainless steel fiber and polyvinyl alcohol fiber are mixed with mixture I for the second time (60 rpm, 5 min) to obtain mixture II.

[0110] A cement-based composite material is prepared.

[0111] Example 9

[0112] This example is carried out by using a similar procedure as that of Example 1, except that the volume ratio of high-strength stainless steel fiber and polyvinyl alcohol fiber is adjusted from 1:1 to 1:4 in this example, and the total volume fraction of high-strength stainless steel fiber and polyvinyl alcohol fiber remains unchanged.

[0113] A cement-based composite material is prepared.

[0114] Comparative Example 1

[0115] This comparative example is carried out by using a similar procedure as that of Example 1, except that in step (2), no polyvinyl ester emulsion and nano-silica solution are added in this comparative example, and the rest of the components and amounts remain unchanged. Specifically:

[0116] Step (2): Dry powder materials are mixed with part of component A (100 rpm, 5 min) to obtain mixture I; the component A contains water, cement, and high-efficiency water reducing agent; the part of component A accounts for 50 wt% of the total component A.

[0117] A cement-based composite material is prepared.

[0118] Comparative Example 2

[0119] This comparative example is carried out by using a similar procedure as that of Example 1, except that the polyvinyl ester emulsion is replaced by an equal weight portion of styrene-acrylic emulsion in this comparative example.

[0120] A cement-based composite material is prepared.

[0121] Comparative Example 3

[0122] This comparative example is carried out by using a similar procedure as that of Example 1, except that the high-strength stainless steel fiber I is replaced by an equal volume of end-hook type steel fiber in this comparative example.

[0123] A cementitious composite material was prepared.

[0124] Comparative Example 4

[0125] This comparative example was carried out using a similar procedure as Example 1, except that high-strength stainless steel fiber I was replaced with an equal volume of milled pin wave steel fiber.

[0126] A cementitious composite material was prepared.

[0127] Comparative Example 5

[0128] This comparative example was carried out using a similar procedure as Example 1, except that polyvinyl alcohol fiber I was replaced with an equal volume of polypropylene fiber.

[0129] A cementitious composite material was prepared.

[0130] Comparative Example 6

[0131] This comparative example was carried out using a similar procedure as Example 1, except that the total volume fraction of high-strength stainless steel fiber and polyvinyl alcohol fiber was adjusted from 2% to 2.5%, and the volume ratio of high-strength stainless steel fiber to polyvinyl alcohol fiber remained unchanged.

[0132] A cementitious composite material was prepared.

[0133] Table 2

[0134]

[0135] Test Example

[0136] The cementitious composite materials prepared in each example and comparative example were tested for performance.

[0137] Compressive strength test method: according to the relevant provisions of GB / T 50081-2019, a INSTRON 1346 universal material testing machine produced by the British Instron Company was used for testing.

[0138] Tensile strength test method: according to the CECS 13-2009 “Standard Test Methods for Fiber Reinforced Concrete”, a UTM 6203 electronic universal testing machine produced by Shenzhen Sanechips Technology Co., Ltd. was used for testing.

[0139] Fracture toughness test method: according to the CECS 13-2009 “Standard Test Methods for Fiber Reinforced Concrete”, a servo hydraulic testing machine with a bending test bench was used for testing.

[0140] The results are shown in Table 3:

[0141] Table 3

[0142] Compressive strength (MPa) Tensile strength (MPa) fracture toughness (kJ / m 2 ) Example 1 128.6 12.8 17.56 Example 2 113.5 10.5 17.28 Example 3 106.7 13.7 16.85 Example 4 100.7 8.5 15.53 Example 5 104.5 8.9 13.82 Example 6 96.5 10.7 12.36 Example 7 95.2 7.9 10.44 Example 8 88.5 5.6 8.85 Example 9 85.2 11.2 10.28 Comparative Example 1 72.5 7.8 7.93 Comparative Example 2 90.2 10.8 11.87 Comparative Example 3 69.8 6.7 9.11 Comparative Example 4 76.8 7.5 10.22 Comparative Example 5 101.6 10.3 15.67 Comparative Example 6 120.8 11.8 17.45

[0143] It can be seen from the above results that the tensile strength, compressive strength and fracture toughness of the cement-based composite material prepared by using the technical scheme provided by the application are more excellent, the mechanical properties and durability are better, and the cement-based composite material is suitable for various building and structural engineering fields.

[0144] The preferred embodiments of the application are described in detail above, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical scheme of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the application and fall within the protection scope of the application.

Claims

1. A composition for the preparation of a cementitious composite material, characterized in that, The composition contains cement, sand, fly ash, silica fume, superplasticizer, thickening agent, water, mixed fiber, polymer emulsion, nano-silica; the polymer emulsion is polyacrylate emulsion and / or VAE-707 with solid content of 50wt%; the content of sand is 35-45wt% relative to 100wt% of the cement, the content of fly ash is 280-320wt%, the content of silica fume is 7-8wt%, the content of superplasticizer is 3.5-4.5wt%, the content of thickening agent is 0.1-0.3wt%, the content of water is 97.8-115wt%, the content of polymer emulsion is 1-3wt%; the content of nano-silica is 0.1-0.3wt%. The mixed fiber is a combination of high-strength stainless steel fiber and polyvinyl alcohol fiber, the volume content of the mixed fiber is 1.5-2.2% based on the total volume of each component in the composition except the mixed fiber; the volume ratio of the high-strength stainless steel fiber to the polyvinyl alcohol fiber is 1:1-3; the high-strength stainless steel fiber is formed by at least two steel ropes spirally wound, and the steel rope is formed by at least seven steel wires spirally wound; the average length of the high-strength stainless steel fiber is 20-60mm, and the average diameter is 0.2-0.8mm; the average length of the polyvinyl alcohol fiber is 6-12mm, and the average diameter is 10-25μm; the nano-silica exists in the form of nano-silica solution, and the solid content in the nano-silica solution is 20-40wt%; the water-binder ratio of the composition is 0.24-0.28:1; the solid content of the polyacrylate emulsion is 50-60wt%; the cement is ordinary portland cement; the sand is quartz sand, and the average particle size of the quartz sand is 0.1-0.3mm; the average particle size of the silica fume is 0.15-0.25μm, and the SiO2 content is ≥95wt%; the thickening agent is bentonite and / or hydroxyethyl methyl cellulose; the superplasticizer is polycarboxylic acid superplasticizer. The method applies each component in the composition of any one of claims 1-6, comprising: (1) first mixing dry powder materials, polymer emulsion, part of component A, and nano-silica to obtain mixture I; the dry powder materials contain sand, fly ash, and silica fume; the component A contains water, cement, and superplasticizer; the part of component A accounts for 40-60wt% of the total component A; The tensile strength of the polyvinyl alcohol fiber is 1.0-1.6 GPa, the elastic modulus is 380-400 cN / dtex, and the density is 1.3-1.5 g / cm 3 .

2. The composition of claim 1, wherein, (2) second mixing the mixture I with mixed fiber to obtain mixture II; 3. The composition according to claim 1 or 2, wherein, The high-strength stainless steel fiber has a tensile strength of 1-2 GPa, an elastic modulus of 100-110 GPa, and a density of 7.9-8.0 g / cm 3 ; and / or, (3) third mixing the mixture II with thickening agent and the remaining component A to obtain mixture III; 4. The composition of claim 1 or 2, wherein, (4) sequentially performing casting and curing treatment on the mixture III to obtain the cement-based composite material.

5. The composition of claim 1 or 2, wherein, ​ 6. The composition of claim 1 or 2, wherein, ​ ​ ​ ​ The average particle size of the fly ash is 0.08-0.12 mm, and the density is 145-210 kg / m 3 ; and / or, ​ ​ 7. A method of making a cementitious composite material, characterized by, ​ ​ ​ ​ ​ 8. The method of claim 7, wherein, In step (2), the method further comprises: first, soaking the mixed fiber in water at 50-60°C for 20-40 min, drying, and then mixing the obtained mixed fiber with the mixture I for the second mixing.

9. A cement-based composite material prepared by the method of claim 7 or 8.

10. Use of the cement-based composite material of claim 9 in building materials.

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