Hydrophobic ultra-high toughness cementitious material and method of making

Abstract

The application provides a hydrophobic super-high toughness cement-based material and a preparation method thereof. According to weight parts, the cement-based material comprises ordinary Portland cement 20-40 parts, first-class fly ash 60-80 parts, quartz sand 18-22 parts, polycarboxylic acid water reducing agent 0.1-0.15 parts, nano calcium carbonate 0.6-1.2 parts, marble stone powder 0.6-2.0 parts, hydroxyl silicone oil 0.4-0.8 parts, polyvinyl alcohol fiber 1-2 parts and water 30-40 parts. The hydrophobic super-high toughness cement-based material of the application adds hydroxyl silicone oil and PVA fiber to form multiple hydrophobic properties. In addition, by adding nano calcium carbonate and marble stone powder, the early hydration of cement can be promoted, and a close packing with the powder material is formed, so that the compressive and tensile strength of the material is ensured. The cement-based material of the application has stable hydrophobic properties and super-high toughness and other mechanical properties, and has high interfacial bonding strength with existing concrete structures, is suitable for repairing and reinforcing concrete structures in marine environments, and can significantly improve the ductility and durability of the reinforced structures.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of marine construction engineering materials, and particularly relates to a hydrophobic super-high toughness cement-based material and a preparation method thereof. BACKGROUND

[0002] The marine environment has many factors such as high humidity and high salt that can easily lead to corrosion of concrete structures, and there are also high-temperature or high-cold climate characteristics in different latitude regions. Among them, high temperature can accelerate the development of steel corrosion, and high cold can easily cause the surface layer of the concrete structure to freeze, thereby aggravating the formation and development of cracks. Therefore, marine engineering structures often face the problem of reinforcement and repair. Fiber reinforced cement-based composite materials based on the design theory of micro mechanics and fracture mechanics have good tensile strain capacity, and also have the characteristics of fine cracks and super-high toughness, and have become a popular material for structural reinforcement in recent years. However, fiber reinforced cement-based materials are hydrophilic materials, and when they are applied to the reinforcement of structures in marine environments, liquid water will continuously wet the surface and enter the interior of the material through connected pores, thereby affecting the durability.

[0003] Concrete structures applied in marine environments usually need to be waterproofed. At present, the waterproofing methods can be divided into two types according to the construction site conditions, namely using waterproof paint and hydrophobically modifying the concrete material. The waterproof paint does not have mechanical properties, is easily affected by ultraviolet aging, and blocks the surface pores of the concrete, causing internal water vapor to accumulate at the interface between the concrete and the paint layer, thereby causing peeling. The hydrophobic modification method is to spray a hydrophobic material on the surface of the concrete substrate to achieve a hydrophobic effect. The Technical Code for Corrosion Protection of Concrete Structures in Harbors (JTJ 275-2000) recommends using isobutyl triethoxysilane to spray the surface of the substrate twice. However, the penetration depth of the silane in this method is usually small, and the protection period is short. If the silane is incorporated into the concrete as a whole, it will result in high cost and large loss of concrete strength; at the same time, during the service of the structure, the concrete material is often in a cracked state, and the crack width is usually 0.2 mm, resulting in a loss of protection effect at the crack development position. Therefore, it is necessary to prepare a cement-based material with excellent hydrophobic properties, mechanical properties and crack resistance for the reinforcement and repair of marine engineering concrete structures to improve the mechanical properties and durability of the reinforced structure. SUMMARY

[0004] The present application aims to provide a hydrophobic super-high toughness cement-based material, which has good hydrophobicity and mechanical properties.

[0005] Another object of the present application is to provide a preparation method of the hydrophobic super-high toughness cement-based material, which is simple in operation and controllable in parameters, and is suitable for industrial large-scale production.

[0006] The present application solves its technical problems by using the following technical solutions.

[0007] The present application provides a hydrophobic super-high toughness cement-based material, which comprises, by weight fraction, 20-40 parts of ordinary Portland cement, 60-80 parts of first-grade fly ash, 18-22 parts of quartz sand, 0.1-0.15 parts of polycarboxylate superplasticizer, 0.6-1.2 parts of nano calcium carbonate, 0.6-2.0 parts of marble stone powder, 0.4-0.8 parts of hydroxyl silicone oil, 1-2 parts of polyvinyl alcohol fiber, and 30-40 parts of water.

[0008] The present application provides a preparation method of the hydrophobic super-high toughness cement-based material, which comprises the following steps:

[0009] S1, each component is taken according to the weight fraction of the hydrophobic super-high toughness cement-based material;

[0010] S2, the ordinary Portland cement, the first-grade fly ash and the quartz sand are mixed and stirred to obtain a mixed powder;

[0011] S3, the water, the polycarboxylate superplasticizer and the nano calcium carbonate are mixed and then ultrasonically treated to obtain a mixed solution;

[0012] S4, the mixed powder and the mixed solution are mixed and stirred, and then the hydroxyl silicone oil is added to obtain a cement mixture;

[0013] S5, the polyvinyl alcohol fiber is added to the cement mixture, and then stirred and cured to obtain the hydrophobic super-high toughness cement-based material.

[0014] The hydrophobic super-high toughness cement-based material and the preparation method thereof have the following advantages:

[0015] The hydrophobic super-high toughness cement-based material of the present application adds hydroxyl silicone oil and PVA fiber, thereby forming multiple hydrophobic properties. In addition, nano calcium carbonate and marble powder are used to promote early hydration of the cement and to form close packing with powder materials of different particle sizes, thereby reducing the porosity of the material and ensuring the compressive and tensile strength of the cement-based material. The cement-based material of the present application has stable hydrophobic properties and super-high toughness and other mechanical properties, and has high interfacial bonding strength with existing concrete structures, and is suitable for repairing and reinforcing concrete structures in marine environments, thereby solving problems such as peeling of the reinforcing layer and repeated reinforcement caused by durability problems, and significantly improving the ductility and durability of the reinforced structure. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be considered as limiting the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0017] Figure 1 The surface hydrophobic effect diagram of the hydrophobic super-high toughness cement-based material of Example 1 of the present application;

[0018] Figure 2 The surface hydrophobic effect diagram of the hydrophobic super-high toughness cement-based material of Example 2 of the present application;

[0019] Figure 3 The surface hydrophobic effect diagram of the cement-based material of Comparative Example 1 of the present application;

[0020] Figure 4 The sessile drop method contact angle test diagram of the hydrophobic super-high toughness cement-based material of Example 1 of the present application;

[0021] Figure 5 The sessile drop method contact angle test diagram of the hydrophobic super-high toughness cement-based material of Example 2 of the present application;

[0022] Figure 6 The sessile drop method contact angle test diagram of the hydrophobic super-high toughness cement-based material of Comparative Example 1 of the present application;

[0023] Figure 7 The tensile test stress-strain diagram of the hydrophobic super-high toughness cement-based material of Examples 1-2 and the cement-based material of Comparative Example 1 of the present application;

[0024] Figure 8 The preparation flowchart of the hydrophobic super-high toughness cement-based material of the present application. DETAILED DESCRIPTION

[0025] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. If specific conditions are not specified in the embodiments, the conventional conditions or the conditions suggested by the manufacturers are adopted. If the manufacturers of the reagents or instruments are not specified, the conventional products that can be purchased in the market are adopted.

[0026] The hydrophobic super-high toughness cement-based material and the preparation method thereof according to the embodiments of the present application will be described in detail below.

[0027] The hydrophobic super-high toughness cement-based material provided by the embodiments of the present application comprises, in terms of weight fractions, 20-40 parts of ordinary Portland cement, 60-80 parts of first-grade fly ash, 18-22 parts of quartz sand, 0.1-0.15 parts of polycarboxylate superplasticizer, 0.6-1.2 parts of nano calcium carbonate, 0.6-2.0 parts of marble stone powder, 0.4-0.8 parts of hydroxyl silicone oil, 1-2 parts of polyvinyl alcohol fiber and 30-40 parts of water. The ultimate tensile strain of the hydrophobic super-high toughness cement-based material prepared by the present application is more than 2.0%, and the static contact angle thereof is greater than 130°.

[0028] The hydroxyl silicone oil and the PVA fiber are adopted in the present application to form multiple hydrophobic properties. On the one hand, the low-molecular-weight polydimethylsiloxane capped with silicon hydroxyl (silanol) will occur condensation reaction in the alkaline pore solution of the cement-based material, is connected with each other to form a polymer through Si-O-Si bond, and further occurs condensation reaction with the hydroxyl in the matrix to be attached to the surface of the matrix through Si-O bond to form a stable film, thereby reducing the surface energy of the cement matrix to achieve the hydrophobic effect. On the other hand, after the polydimethylsiloxane completes the self-condensation reaction, it reacts with the polyvinyl alcohol containing hydroxyl to form a Si-O bond, thereby forming a hydrophobic film on the surface of the fiber. In addition, the hydrophobic angle of the PVA fiber adopted in the present application can reach 120°. The hydroxyl silicone oil and the PVA fiber are added to the cement-based material in the present application, so that the cement-based material has stable hydrophobic properties, and the material still has hydrophobic properties in the stress cracking state.

[0029] The condensation reaction between the hydroxyl silicone oil and the cement matrix is as follows:

[0030]

[0031] The condensation reaction between the PVA fiber and the hydroxyl silicone oil is as follows:

[0032]

[0033] Further, in the preferred embodiments of the present application, the length of the polyvinyl alcohol fiber is 10-15 mm, the diameter thereof is 10-15 μm, the tensile strength thereof is not less than 1500 MPa, and the elastic modulus thereof is not less than 39 GPa.

[0034] Further, in the preferred embodiment of the present application, the average particle size of the ordinary Portland cement is 30-100 μm, the average particle size of the primary fly ash is 10-45 μm, and the average particle size of the quartz sand is 400-600 μm.

[0035] Further, in the preferred embodiment of the present application, the average particle size of the marble stone powder is 0.2-10 μm, and the average particle size of the nano calcium silicate is 20-200 nm.

[0036] Further, in the preferred embodiment of the present application, the hydroxyl silicone oil is a dimethicone capped with a silanol. It is to be noted that, in order to prevent the hydroxyl silicone oil from affecting the hydration reaction of the cement, the dimethicone used has the characteristics of low viscosity, low polymerization and high hydroxyl value, and the nano calcium carbonate and the marble stone powder with calcium carbonate as the main component are used to avoid the agglomeration of fine particles through ultrasonic dispersion treatment, so as to promote the early hydration of the cement and make the cement form a close packing with the powder materials of different particle sizes, thereby reducing the porosity of the material and ensuring the compressive and tensile strength of the cement-based material.

[0037] Further, in the preferred embodiment of the present application, the water-binder ratio of the hydrophobic super-high toughness cement-based material is 0.3-0.4.

[0038] The hydrophobic super-high toughness cement-based material of the present application has stable hydrophobic properties and super-high toughness and the like, and has high interfacial bonding strength with existing concrete structures, and is suitable for repairing and reinforcing concrete structures in marine environments, thereby solving the problems of peeling of the reinforcing layer and repeated reinforcement caused by durability problems, and significantly improving the ductility and durability of the reinforced structure.

[0039] Referring to Figure 8 The present application also provides a preparation method of the hydrophobic super-high toughness cement-based material, comprising the following steps:

[0040] S1. The components are weighed according to the weight fraction of the hydrophobic super-high toughness cement-based material.

[0041] S2. The ordinary Portland cement, the primary fly ash and the quartz sand are mixed and stirred to obtain a mixed powder.

[0042] Further, in the preferred embodiment of the present application, the stirring time is 60-120 s.

[0043] S3. The water, the polycarboxylate-based water reducing agent and the nano calcium carbonate are mixed and then ultrasonically treated to obtain a mixed solution.

[0044] S4. The mixed powder and the mixed solution are mixed and stirred, and then the hydroxyl silicone oil is added to obtain a cement mixture.

[0045] Further, in the preferred embodiment of the present application, the stirring time is 120-180 s, and the stirring speed is 135-145 r / min.

[0046] S5, adding the polyvinyl alcohol fiber into the cement mixture, stirring and curing to obtain the hydrophobic super-high toughness cement-based material. The curing in the present application is the conventional curing of cement, and the specific steps are as follows: the cement mixture is molded, demolded after 24 h, and then placed in an environmental test chamber for curing for 28 days.

[0047] Further, in the preferred embodiment of the present application, the stirring time is 180-300 s, and the stirring speed is 275-295 r / min.

[0048] The features and properties of the present application are further described in detail below in combination with examples.

[0049] Example 1

[0050] The hydrophobic super-high toughness cement-based material provided in the present embodiment is prepared according to the following method:

[0051] (1) 308 g of P.O. 42.5 ordinary portland cement, 462 g of Class I fly ash, and 154 g of quartz sand are slowly stirred in a cement mixer for 120 s to obtain a mixed powder. The average particle size of the ordinary portland cement is 30-100 μm, the average particle size of the Class I fly ash is 10-45 μm, and the average particle size of the quartz sand is 10-45 μm. The ordinary portland cement and the Class I fly ash can be purchased from Xiamen Meiyi Building Materials Co., Ltd.

[0052] (2) 231 g of water is mixed with 0.7 g of polycarboxylate superplasticizer to obtain a solution, and 10 g of nano calcium carbonate and 10 g of marble stone powder are added to the solution. The solution is treated with an ultrasonic cleaner with a power of 270 W for 2 min to obtain a mixed solution. The mixed solution has the characteristic of not being layered for 3 min. The average particle size of the marble stone powder is 0.2-10 μm, and the average particle size of the nano calcium carbonate is 20-200 nm. The polycarboxylate superplasticizer can be XT-800 type superplasticizer from Xiamen Lubao Xiangtong Building Materials Co., Ltd.

[0053] (3) The mixed solution is added to the mixed powder, and after slow stirring for 180 s, 4.7 g of silanol-terminated polydimethylsiloxane is added to obtain a cement mixture.

[0054] (4) Turn the speed of the cement mixer to high speed, and sprinkle 15.4 g of polyvinyl alcohol fiber into the cement mixture. After mixing for 240 s until the polyvinyl alcohol fiber is uniformly dispersed, the cement mixture is placed in a mold, demolded after 24 h, and placed in an environmental test chamber for curing. After 28 days of curing, a hydrophobic super-high-toughness cement-based material is obtained.

[0055] Example 2

[0056] The hydrophobic super-high-toughness cement-based material provided in this example is prepared according to the following method:

[0057] (1) 308 g of P.O. 42.5 ordinary portland cement, 1230 g of Class 1 fly ash, and 308 g of quartz sand are slowly stirred in a cement mixer for 120 s to obtain a mixed powder. The average particle size of the ordinary portland cement is 30-100 μm, the average particle size of the Class 1 fly ash is 10-45 μm, and the average particle size of the quartz sand is 10-45 μm. The ordinary portland cement and the Class 1 fly ash can be purchased from Xiamen Meiyi Building Materials Co., Ltd.

[0058] (2) 462 g of water is mixed with 1.54 g of polycarboxylate superplasticizer to obtain a solution, and 10 g of nano calcium carbonate and 10 g of marble stone powder are added to the solution. The solution is treated with an ultrasonic cleaner with a power of 270 W for 2 min to obtain a mixed solution. The mixed solution has the characteristic of not separating into layers for 3 min. The average particle size of the marble stone powder is 0.2-10 μm, and the average particle size of the nano calcium carbonate is 20-200 nm. The polycarboxylate superplasticizer can be XT-800 type superplasticizer from Xiamen Lujiaoxiangtong Building Materials Co., Ltd.

[0059] (3) The mixed solution is added to the mixed powder, and after slowly stirring for 180 s, 4.7 g of silanol-terminated polydimethylsiloxane is added to obtain a cement mixture.

[0060] (4) Turn the speed of the cement mixer to high speed, and sprinkle 15.4 g of polyvinyl alcohol fiber into the cement mixture. After mixing for 240 s until the polyvinyl alcohol fiber is uniformly dispersed, the cement mixture is placed in a mold, demolded after 24 h, and placed in an environmental test chamber for curing. After 28 days of curing, a hydrophobic super-high-toughness cement-based material is obtained.

[0061] Comparative Example 1

[0062] The cement-based material provided in this comparative example is prepared according to the following method:

[0063] (1) 308 g PO42.5 ordinary Portland cement, 462 g first-grade fly ash, and 154 g quartz sand were slowly stirred in a cement mixer for 120 s to obtain a mixed powder. The average particle size of the ordinary Portland cement was 30-100 μm, the average particle size of the first-grade fly ash was 10-45 μm, and the average particle size of the quartz sand was 10-45 μm. Both PO42.5 ordinary Portland cement and first-grade fly ash were purchased from Xiamen Meiyi Building Materials Co., Ltd.

[0064] (2) 231 g of water and 0.7 g of a polycarboxylic acid-based high-efficiency water reducer were mixed to obtain a solution, and 10 g of nano-calcium carbonate and 10 g of marble powder were added thereto. The solution was treated with an ultrasonic cleaner having a power of 270 W for 2 minutes to obtain a mixed solution. The mixed solution had the characteristic of not stratifying after standing for 3 minutes. The average particle size of the marble powder was 0.2 to 10 μm, and the average particle size of the nano-calcium silicate was 20 to 200 nm. The polycarboxylic acid-based high-efficiency water reducer can be the XT-800 water reducer produced by Xiamen Luqiao Xiangtong Building Materials Co., Ltd.

[0065] (3) The mixed solution was added to the mixed powder, and after slow stirring for 180 seconds, 4.7 g of isobutyltriethoxysilane was added to obtain a cement mixture.

[0066] (4) The cement mixer was rotated to high speed, and 15.4 g of polyvinyl alcohol fiber was sprinkled into the cement mixture. The mixture was mixed for 240 s until the polyvinyl alcohol fiber was evenly dispersed. The cement mixture was molded and demolded after 24 h. The mixture was placed in an environmental test chamber for curing. After curing for 28 days, a cement-based material was obtained.

[0067] Test Example 1

[0068] This test example uses the sessile drop method and axial tensile test to test the static hydrophobic angle and axial tensile performance of the hydrophobic ultra-high toughness cement-based materials of Examples 1-2 and the cement-based material of Comparative Example 1. The static contact angle measurement results are shown in Table 1.

[0069] Table 1 Static contact angle measurement data

[0070]

[0071] like Figure 1 Shown is a diagram showing the surface hydrophobic effect of the hydrophobic ultra-high toughness cement-based material of Example 1. Figure 2 Shown is a diagram showing the surface hydrophobic effect of the hydrophobic ultra-high toughness cement-based material of Example 2. Figure 3 Shown is a diagram showing the surface hydrophobic effect of the cement-based material of Comparative Example 1. Figure 4 Shown is a sessile drop contact angle test diagram of the hydrophobic ultra-high toughness cement-based material of Example 1. Figure 5The figure shows the sessile drop method contact angle test of the hydrophobic ultra-high toughness cementitious material of Example 2. Figure 6 The figure shows the sessile drop method contact angle test of the cementitious material of Comparative Example 1. Figure 7 The figure shows the tensile test stress-strain diagram of the hydrophobic ultra-high toughness cementitious material of Examples 1-2 and the cementitious material of Comparative Example 1.

[0072] The hydrophobic ultra-high toughness cementitious materials of Examples 1 and 2 are mainly different in the dosage of fly ash material, but have the same water-binder ratio. From the tensile test stress-strain diagrams of the hydrophobic ultra-high toughness cementitious materials of Examples 1 and 2, it can be seen that the hydrophobic ultra-high toughness cementitious material of Example 1 has a relatively large ultimate tensile strain, and the hydrophobic angle is greater than 130°. Figures 1 to 7 As can be seen from the above and Table 1, the hydrophobic ultra-high toughness cementitious materials of Examples 1 and 2 both have the characteristics of ultimate tensile strain greater than 2% and hydrophobic angle greater than 130°. Among them, the cementitious material of Example 2 with high fly ash dosage has a relatively large ultimate tensile strain. Comparative Example 1 uses a different siloxane material from the present application, and compared with the cementitious material of Example 1, the cementitious material of Comparative Example 1 also has hydrophobic properties, but the obtained hydrophobic angle is relatively small, and the ultimate tensile strain also decreases.

[0073] The above-described examples are part of the embodiments of the present application, but not all the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

Claims

1. A hydrophobic ultra-high toughness cementitious material, characterized in that, According to weight parts, including: ordinary Portland cement 20~40 parts, first fly ash 60~80 parts, quartz sand 18~22 parts, polycarboxylic acid water reducing agent 0.1~0.15 parts, nano calcium carbonate 0.6~1.2 parts, marble stone powder 0.6~2.0 parts, hydroxyl silicone oil 0.4~0.8 parts, polyvinyl alcohol fiber 1~2 parts, water 30~40 parts;The hydroxyl silicone oil is a silanol-terminated polydimethylsiloxane;The length of the polyvinyl alcohol fiber is 10~15mm, the diameter is 10~15μm, the tensile strength is not less than 1500MPa, and the elastic modulus is not less than 39GPa;Wherein, in the preparation process, nano calcium carbonate and marble stone powder with main component of calcium carbonate are used, and the fine particle agglomeration phenomenon is avoided by ultrasonic dispersion treatment, the early hydration of cement is promoted, and the close packing of different particle size powder materials is formed, and the material porosity is reduced.

2. The hydrophobic ultra-high toughness cementitious material of claim 1, wherein, The average particle size of the ordinary Portland cement is 30~100μm, the average particle size of the first fly ash is 10~45μm, and the average particle size of the quartz sand is 400~600μm.

3. The hydrophobic ultra-high toughness cementitious material of claim 1, wherein, The average particle size of the marble stone powder is 0.2~10μm, and the average particle size of the nano calcium carbonate is 20~200nm.

4. The hydrophobic ultra-high toughness cementitious material of claim 1, wherein, The water-binder ratio of the hydrophobic super high toughness cement-based material is 0.3~0.

4.

5. A method for preparing a hydrophobic ultra-high toughness cementitious material, characterized in that, Including the following steps: S1, the weight parts of the hydrophobic super high toughness cement-based material according to any one of claims 1~4 are taken for each component; S2, the ordinary Portland cement, the first fly ash and the quartz sand are mixed and stirred to obtain a mixed powder; S3, the water, the polycarboxylic acid water reducing agent and the nano calcium carbonate are mixed and then ultrasonically treated to obtain a mixed solution; S4, the mixed powder and the mixed solution are mixed and stirred, and then the hydroxyl silicone oil is added to obtain a cement mixture; S5, the polyvinyl alcohol fiber is added to the cement mixture, and stirred and cured to obtain the hydrophobic super high toughness cement-based material.

6. The production method according to claim 5, wherein In step S2, the stirring time is 60~120s.

7. The preparation method according to claim 5, characterized in that In step S4, the stirring time is 120~180s, and the stirring speed is 135~145r / min.

8. The preparation method according to claim 5, characterized in that In step S5, the stirring time is 180~300s, and the stirring speed is 275~295r / min.

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