Cement reinforcing additive and preparation method thereof

Abstract

The invention relates to the field of building materials, and particularly discloses a cement reinforcing additive and a preparation method thereof.The cement reinforcing additive is prepared from raw materials including modified inorganic component suspension modified through a silane coupling agent and containing double bonds, organic components and an initiator, the weight part ratio of the organic component to the modified inorganic component which is modified by the silane coupling agent and contains double bonds is 1: (0.3-1.2); after a suspension of modified inorganic components and organic components which are modified by a silane coupling agent and contain double bonds is added into the cement-based material, a gelling network and a polymer network are interspersed and distributed in a net shape. According to the invention, the fracture resistance of the cement-based material can be better improved, so that the cement-based material has good compressive strength and fracture resistance.

Description

Technical Field

[0001] The present invention relates to the field of building materials, and more specifically, to a cement reinforcing additive and a preparation method thereof. Background Art

[0002] Cement-based composites have become the main building materials in the world due to their abundant raw materials, low cost, high strength, and simple production process. They are widely used in large-scale projects such as civil buildings, roads, bridges, airports, ports, and water conservancy. However, cement-based composites are non-uniform porous brittle materials. When subjected to external loads, stress is first concentrated at the defects, and nanocracks are generated at the loosely accumulated hydration products and gradually expand into micron cracks. Under continuous load, micron cracks continue to expand and merge to form macro cracks, which in turn lead to brittle fracture of the material. The presence of pores and cracks not only reduces the strength of cement-based composites, but also induces problems such as penetration. The intrusion of harmful ions reduces the durability of cement-based composites, increases maintenance costs, and shortens the service life of cement-based composites. Therefore, strengthening cement-based composites has become one of the current research hotspots.

[0003] Studies have shown that by introducing some high-toughness materials, among which fibers and polymer emulsions are two materials that have been studied more and are widely used. However, fibers are unevenly dispersed during concrete mixing and are easy to agglomerate, resulting in poor workability and difficulty in pumping; in addition, since the toughening of fibers in concrete mainly relies on the plug-in effect to limit the development of cracks, the performance of fiber-modified concrete is closely related to the dispersion and orientation of fibers. Therefore, the stability of fiber-modified concrete is difficult to control, and more aspects need to be paid attention to during actual use. The improvement of the flexural strength of polymer emulsion-modified concrete often requires sacrificing the compressive strength of cement-based materials. For example, in the work reported by Farshad Farshchi Tabrizi in 2019, SBA-modified concrete was used to increase the flexural strength by 22.6%, but the compressive strength decreased significantly. This decline is mainly due to the fact that traditional additives such as fibers and polymer emulsions are not active, neither participate in the hydration reaction nor promote the hydration process. They are mainly physical, and their role in concrete is only related to their own physical properties, and they have no modification effect on the microstructure of concrete.

[0004] The Chinese patent with publication number CN111517703A discloses a high-flexural-resistance cement-based material and a preparation method thereof, and relates to the field of concrete technology. The high-flexural-resistance cement-based material includes cement hydrate and a polymer chemically bonded to the cement hydrate, and the polymer is obtained by in-situ polymerization of polymerization monomers in cement under the action of an initiator and an accelerator. The preparation method of the high-flexural-resistance cement-based material is as follows: the polymerization monomers, an initiator and an accelerator are mixed and dissolved, and then in-situ polymerization is carried out in cement. The formed polymer and cement hydrate are connected by chemical bonding, which effectively improves the flexural strength of the cement-based material. However, in this method, the organic components and the inorganic components are mainly connected through -COOH and Ca in cement. 2+ Weak hydrogen bond interactions occur, and their actual binding effect is limited.

[0005] The Chinese patent with publication number CN115368106A provides a high-strength cement concrete and a preparation method thereof, belonging to the field of building materials technology. Through modification, a layer of hyperbranched structure can be formed on the surface of ultra-short steel fibers, which can significantly increase the roughness of the surface of ultra-short steel fibers, greatly improve the interface friction, physical adsorption and chemical bonding strength between interfaces, solve the technical problem of poor toughness of cement concrete, and achieve balance and unity of high strength and high toughness in cement concrete materials. However, the fundamental problem that the introduction of fibers leads to poor working performance of concrete has not been solved.

[0006] The Chinese patent with announcement number CN105713125B discloses an organic-inorganic hybrid particle and its preparation method and application in cement-based material modification, which belongs to the field of admixtures for cement-based material modification. By preparing organic-inorganic hybrid particles as reinforcing agents, the organic components and the inorganic components are mutually connected by covalent bonds, which are not core-shell structures, but are interspersed with each other and connected by covalent chemical bonds, wherein siloxane D is the main source of the inorganic components of the organic-inorganic hybrid particles; the aqueous dispersion of the organic-inorganic hybrid particles is used as a reinforcing agent for cement-based materials, which can simultaneously improve the compression, flexural and tensile (or splitting) strength of cement-based materials.

[0007] Although there are covalent bonds between the organic phase and the inorganic phase in the above organic-inorganic hybrid particles, which is conducive to their stable dispersion and can improve the compressive strength of cement-based materials, the improvement of the performance of cement materials by the above organic-inorganic hybrid particles mainly depends on the promotion of hydration by the inorganic component, in which the organic component only provides spatial repulsion between the inorganic nanoparticles to ensure better dispersion of the inorganic component, and does not fully exert the enhancement effect of the organic component on toughness. Summary of the invention

[0008] In order to better improve the flexural properties of cement-based materials so that the cement-based materials have both good flexural and compressive properties, the present application provides a cement reinforcing additive and a preparation method thereof.

[0009] In the first aspect, the present application provides a cement reinforcing additive, which adopts the following technical solution:

[0010] A cement reinforcing additive is prepared from raw materials including a modified inorganic component suspension modified by a silane coupling agent and containing double bonds, an organic component, and an initiator, wherein the weight ratio of the organic component to the modified inorganic component modified by a silane coupling agent and containing double bonds is 1:(0.3-1.2); after the modified inorganic component modified by a silane coupling agent and containing double bonds and the organic component suspension are added to a cement-based material, the modified inorganic component modified by a silane coupling agent and containing double bonds is connected with hydrated particles in the cement-based material to form a gelling network, the modified inorganic component modified by a silane coupling agent and containing double bonds forms a polymer network with the organic component through the action of double bonds and the action of the initiator, and the gelling network and the polymer network are interlaced and distributed in a network shape.

[0011] By adopting the above technical scheme, firstly, the modified inorganic component suspension and the organic component are added to the cement-based material separately with the initiator, and the modified inorganic component suspension modified by the silane coupling agent and containing double bonds can be uniformly dispersed in the cement-based material; and in the cement-based material, the modified inorganic component and the hydrated particles in the cement-based material are connected to form a gelling network, and the double bonds on the organic component and the modified inorganic component can be in-situ polymerized under the action of the initiator to form a polymer network, thereby forming an interpenetrating network structure and a mesh distribution. Furthermore, in addition to connecting the network structure and cement-based materials by connecting with hydrated particles, the interlaced network structure formed in the present application is also distributed in the cement-based material in a mesh-like manner, and the various parts of the network structure are in a continuous state, which can present a "bundled" state to the various parts of the cement-based material; compared with the network structure formed by the prior art, which is relatively independent and dispersedly distributed in the cement-based material, the network structure of the present application can be distributed more evenly in the cement-based material, and the compatibility and bonding force between the gel network and the polymer network, and between the network structure and the cement-based material are more excellent, so that the flexural properties of the cement-based material can be better improved; at the same time, the process of forming the network structure of the present application and the process of hydration of the cement-based material occur simultaneously, which has almost no effect on the hydration, will not delay the hydration of cement, will not have a negative impact on the compressive properties of the cement-based material, and can further improve the compressive properties of the cement-based material. Therefore, the present application can better improve the flexural properties of the cement-based material, so that the cement-based material has both good compressive strength and flexural strength.

[0012] Furthermore, the modified inorganic component modified by a silane coupling agent and containing double bonds is a modified nano calcium silicate suspension, and the preparation method of the modified nano calcium silicate suspension comprises the following steps:

[0013] (1) mixing a calcium source, a silicon source, a silane coupling agent, a water reducing agent and water, adjusting the pH value to 4-7, and stirring to obtain a precursor solution;

[0014] (2) The pH value of the precursor solution is adjusted to 10-14, and the reaction is stirred to obtain a modified nano-calcium silicate suspension.

[0015] By adopting the above technical scheme, the present application first prepares a stable modified nano calcium silicate suspension, which can not only be evenly dispersed in cement-based materials; but also in cement-based materials, the modified nano calcium silicate can be more stably connected with the hydrated particles in the cement-based materials to form a gel network, and at the same time, more stably in situ polymerize with organic components under the action of an initiator to form a polymer network, forming a mutually interlaced network structure and a mesh distribution. The flexural properties of cement-based materials can be better improved, so that the cement-based materials have both good compressive strength and flexural strength.

[0016] Further, in the preparation step (1) of the modified nano calcium silicate suspension, the stirring temperature is 15-70°C and the stirring time is 0.2-2 hours. In the preparation step (2) of the modified nano calcium silicate suspension, the stirring temperature is 15-90°C and the stirring time is 5-15 hours. Further, the calcium source is at least one of calcium chloride, calcium nitrate tetrahydrate, calcium hydrogen phosphate, calcium formate, and calcium acetate. The silicon source is at least one of tetraethoxysilane, tetramethoxysilane, trimethoxysilane, and triethoxysilane. The ratio of the amount of the calcium source to the silicon source is (0.9-3.3):1; the mass ratio of the silane coupling agent to the silicon source is (0.3-1):1. The water reducer is a polycarboxylic acid water reducer, and the mass ratio of the water reducer to the calcium source is (0.2-3):1.

[0017] By adopting the above technical scheme, the preparation conditions and raw material ratio of the modified nano calcium silicate suspension are optimized, which is conducive to forming a more stable modified nano calcium silicate suspension, thereby being more conducive to forming a stable network structure and better improving the performance of cement-based materials.

[0018] Furthermore, the silane coupling agent is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, methacryloxymethyltriethoxysilane, acryloxymethyltrimethoxysilane and acryloxypropyltrimethoxysilane.

[0019] Furthermore, the organic component includes at least one of the following components, and the general formula of the organic component is as follows:

[0020]

[0021] Where R 1 Indicates H, CH 3 or CH 3 COOH, R 2 Represents H or active metal ions; R 3 Indicates H or CH 3 , R 4 , R 5 H and CH are represented independently 3 , CH 2 CH 3 , CH 2 OH, CH 2 CH 2 OH, CH 2 CHCH 3 OH; R 6 , R 7 and R 8 Each independently represents H or CH 3 , R 9 represents an alkyl group having 4 to 30 carbon atoms; X 1 , X 2 and X 3 Each independently represents O or NH; a and b each independently represent ethoxy -CH 2 CH 2 The average number of repeating units of the O-link, a and b range from 4 to 50.

[0022] Furthermore, the amount of the initiator is 0.1-5% of the mass of the organic component. The initiator is a free radical initiator, and is a medium-temperature thermal initiator or a redox initiation system.

[0023] By adopting the above technical scheme, the preparation conditions and raw material ratio of the modified nano calcium silicate suspension are optimized, which is conducive to forming a more stable modified nano calcium silicate suspension, thereby being more conducive to forming a stable network structure and better improving the performance of cement-based materials.

[0024] In a second aspect, the present application provides a method for preparing a cement reinforcing additive, using the following technical solution:

[0025] A method for preparing a cement reinforcing additive comprises the following steps: adding organic components and water as agent A and initiator solution as agent B to a modified nano calcium silicate suspension, and agent AB is the cement reinforcing additive.

[0026] In summary, this application has the following beneficial effects:

[0027] 1. In the reinforcing additive system of the present application, the modified inorganic components, organic components and water-based materials can form a network structure that intersperses with each other and is distributed in a mesh. The various parts of this network structure are in a continuous state. Therefore, compared with the conventional independent and dispersed network structures formed in the cement system, the network structure of the present application can present a "bundled" state for the various parts of the cement-based material; the network structure of the present application can be distributed more evenly in the cement-based material, and the compatibility and bonding between the gel network and the polymer network, and between the network structure and the cement-based material are better, so that the flexural resistance of the cement-based material can be better improved.

[0028] 2. The construction process of the network structure of the present application and the hydration process of the cement-based material occur simultaneously, which has almost no effect on the hydration, will not delay the hydration of the cement, will not have a negative impact on the compressive properties of the cement-based material, and can further improve the compressive properties of the cement-based material.

[0029] 3. Compared with the traditional method of directly adding polymer emulsion or fiber, this method has less organic component addition and has no negative impact on the working performance of cement-based materials, and even improves the working performance under some conditions. Compared with the traditional method of adding inorganic nanoparticles or hybrid nanoparticles, this method can more effectively play the role of nanoparticles in cement-based materials, that is, as part of the bridge, connecting the hydration products and organic components, effectively improving the flexural strength. DETAILED DESCRIPTION

[0030] The present application is further described in detail below with reference to the embodiments.

[0031] Example

[0032] This embodiment provides a cement reinforcing additive, which is prepared from raw materials including a modified inorganic component suspension modified by a silane coupling agent and containing double bonds, an organic component, and an initiator. The preparation method of the cement reinforcing additive is: adding an organic component and water as an agent A to the modified inorganic component suspension containing double bonds, and an initiator solution as an agent B, and the AB agent is the cement reinforcing additive.

[0033] The weight ratio of the organic component to the modified inorganic component modified by the silane coupling agent and containing double bonds is 1:(0.3-1.2); the amount of the initiator is 0.1-5% of the organic component. The initiator is a free radical initiator, and is a medium-temperature thermal initiator or a redox initiation system.

[0034] In a specific embodiment, the medium temperature thermal initiator includes one of azobisisobutylamidine hydrochloride, azobisisobutyronitrile, azobisisoheptylonitrile, and dimethyl azobisisobutyrate. In the redox system initiator, the oxidant is at least one of ammonium persulfate and sodium persulfate, and the reducing agent is at least one of oxalic acid, sodium sulfite, and triethanolamine.

[0035] The specific material structure of the organic component is shown in Table 1.

[0036] Table 1 Material structure of organic components

[0037]

[0038]

[0039] The modified inorganic component suspension in this embodiment is a modified nano calcium silicate suspension or a modified nano silicon dioxide suspension. In the cement reinforcing additive of the present application, after the modified inorganic component suspension and the organic component are added to the cement-based material, the modified inorganic component and the hydrated particles in the cement-based material are connected to form a gel network, and the modified inorganic component forms a polymer network with the organic component through double bond action and initiator action, and the gel network and the polymer network are interspersed and distributed in a network.

[0040] The embodiment of the present application provides a method for preparing a modified nano calcium silicate suspension, comprising the following steps:

[0041] (1) mixing a calcium source, a silicon source, a silane coupling agent, a water reducing agent and water, adjusting the pH value to 4-7, and stirring to obtain a precursor solution;

[0042] (2) The pH value of the precursor solution is adjusted to 10-14, and the reaction is stirred to obtain a modified nano-calcium silicate suspension.

[0043] Furthermore, in the preparation step (1) of the modified nano-calcium silicate suspension, the stirring temperature is 15-70° C. and the stirring time is 0.2-2 hours.

[0044] Furthermore, in the preparation step (2) of the modified nano-calcium silicate suspension, the stirring temperature is 15-90° C. and the stirring time is 5-15 hours.

[0045] The calcium source is at least one of calcium chloride, calcium nitrate tetrahydrate, calcium hydrogen phosphate, calcium formate, and calcium acetate.

[0046] The silicon source is at least one of tetraethoxysilane, tetramethoxysilane, trimethoxysilane and triethoxysilane.

[0047] The ratio of the amount of calcium source to the amount of silicon source is (0.9-3.3):1.

[0048] The silane coupling agent is at least one of vinyltrimethoxysilane (VMES), vinyltriethoxysilane (VTES), methacryloxypropyltrimethoxysilane (MAPTMS), methacryloxypropyltriethoxysilane (MAPTES), methacryloxymethyltriethoxysilane (AAPTES), acryloxymethyltrimethoxysilane (AAMTMS), and acryloxypropyltrimethoxysilane (AAPTMS).

[0049] The mass ratio of the silane coupling agent to the silicon source is (0.3-1):1.

[0050] The water reducer is a polycarboxylate water reducer, specifically a polycarboxylate water reducer PCE-1 commercially available from Jiangsu Subote New Materials Co., Ltd. The mass ratio of the water reducer to the calcium source is (0.2-3):1.

[0051] In this embodiment, the mass ratio of the modified nano-calcium silicate and the organic component is calculated as follows: {(mass of calcium source+mass of silicon source)*0.86} / mass of organic component, where 0.86 is the reaction conversion rate.

[0052] The following is an explanation through specific examples.

[0053] Example 1

[0054] Example 1 provides a method for preparing a modified nano calcium silicate suspension, wherein the raw materials include the following components:

[0055] Calcium source: 1g calcium acetate; 0.4g water reducer; silicon source: 0.7g trimethoxysilane; silane coupling agent: 0.3g MAPTEMS; 100g water. The molar ratio of calcium source to silicon source is 1.1:1. The mass ratio of water reducer to calcium source is 0.4:1. The mass ratio of silane coupling agent to silicon source is 0.4:1.

[0056] The preparation steps of a modified nano calcium silicate suspension are as follows:

[0057] (1) Add a calcium source, a silicon source, a silane coupling agent, a water reducing agent and water into a reactor, add 0.1 M hydrochloric acid, adjust the pH value to 4, and stir for 1 hour in a water bath at 20° C. to obtain a precursor solution.

[0058] (2) Add 4M sodium hydroxide aqueous solution to the precursor solution, adjust the pH value of the precursor solution to 14, raise the temperature to 45° C., and stir the reaction under nitrogen protection for 6 hours to obtain a modified nano-calcium silicate suspension.

[0059] Example 1 also provides a method for preparing a cement reinforcing additive, wherein the raw materials include the following components: organic component: 2.25g P1; 101.46g modified nano calcium silicate solution; initiator: 0.1g azobisisoheptanenitrile. The mass ratio of modified nano calcium silicate to organic component is 0.65:1. The mass ratio of initiator to organic component is 0.04:1.

[0060] The preparation steps of a cement reinforcing additive are as follows: an organic component is mixed with 50g of water to prepare an aqueous solution of the organic component, and then a modified nano calcium silicate suspension is added to the aqueous solution of the organic component as agent A, and an initiator is mixed with 30g of water as agent B. Agents AB are cement reinforcing additives.

[0061] Example 2

[0062] Example 2 provides a method for preparing a modified nano calcium silicate suspension, wherein the raw materials include the following components:

[0063] Calcium source: 2g calcium acetate; 0.8g water reducer; silicon source: 1.4g trimethoxysilane; silane coupling agent: 0.6g MAPTEMS; 100g water. The molar ratio of calcium source to silicon source is 1.1:1. The mass ratio of water reducer to calcium source is 0.4:1. The mass ratio of silane coupling agent to silicon source is 0.4:1.

[0064] The preparation steps of a modified nano calcium silicate suspension are as follows:

[0065] (1) Add a calcium source, a silicon source, a silane coupling agent, a water reducing agent and water into a reactor, add 0.1 M hydrochloric acid, adjust the pH value to 4, and stir for 3 hours in a water bath at 20° C. to obtain a precursor solution.

[0066] (2) 4 M sodium hydroxide was added to the precursor solution, the pH value of the precursor solution was adjusted to 14, the temperature was raised to 30° C., and the reaction was stirred for 12 hours under nitrogen protection to obtain a modified nano-calcium silicate suspension.

[0067] Example 2 also provides a method for preparing a cement reinforcing additive, wherein the raw materials include the following components: organic component: 4.5 g P1; 102.92 g modified nano calcium silicate suspension; initiator: 0.2 g azobisisoheptanenitrile. The mass ratio of modified nano calcium silicate to organic component is 0.65:1. The mass ratio of initiator to organic component is 0.04:1.

[0068] The preparation steps of a cement reinforcing additive are as follows: an organic component is mixed with 50g of water to prepare an aqueous solution of the organic component, the aqueous solution of the organic component and a modified nano-calcium silicate suspension are mixed as agent A, and an initiator is mixed with 30g of water as agent B. Agents AB are cement reinforcing additives.

[0069] Example 3

[0070] Example 3 provides a method for preparing a modified nano calcium silicate suspension, wherein the raw materials include the following components:

[0071] Calcium source: 4g calcium acetate; 1.6g water reducer; silicon source: 2.8g trimethoxysilane; silane coupling agent: 1.2g MAPTEMSS; 100g water. The molar ratio of calcium source to silicon source is 1.1:1. The mass ratio of water reducer to calcium source is 0.4:1. The mass ratio of silane coupling agent to silicon source is 0.4:1.

[0072] The preparation steps of a modified nano calcium silicate suspension are as follows:

[0073] (1) Add a calcium source, a silicon source, a silane coupling agent, a water reducing agent and water into a reactor, add 0.1 M hydrochloric acid, adjust the pH value to 5, and stir for 3 hours in a water bath at 20° C. to obtain a precursor solution.

[0074] (2) 4 M sodium hydroxide was added to the precursor solution, the pH value of the precursor solution was adjusted to 12, the temperature was raised to 30° C., and the reaction was stirred for 12 hours under nitrogen protection to obtain a modified nano-calcium silicate suspension.

[0075] Example 3 also provides a method for preparing a cement reinforcing additive, wherein the raw materials include the following components: organic component: 9g P1; 105.85g modified nano calcium silicate suspension; initiator: 0.2g azobisisoheptanenitrile. The mass ratio of modified nano calcium silicate to organic component is 0.65:1. The mass ratio of initiator to organic component is 0.04:1.

[0076] The preparation steps of a cement reinforcing additive are as follows: an organic component is mixed with 50g of water to prepare an aqueous solution of the organic component, and then a modified nano calcium silicate suspension is added to the aqueous solution of the organic component as agent A, and an initiator is mixed with 30g of water as agent B. Agents AB are cement reinforcing additives.

[0077] Example 4

[0078] Example 4 provides a method for preparing a modified nano calcium silicate suspension, wherein the raw materials include the following components:

[0079] Calcium source: 8g calcium acetate; 3.2g water reducer; silicon source: 5.6g trimethoxysilane; silane coupling agent: 2.4g MAPTEMS; 100g water. The molar ratio of calcium source to silicon source is 1.1:1. The mass ratio of water reducer to calcium source is 0.4:1. The mass ratio of silane coupling agent to silicon source is 0.4:1.

[0080] The preparation steps of a modified nano calcium silicate suspension are as follows:

[0081] (1) Add a calcium source, a silicon source, a silane coupling agent, a water reducing agent and water into a reactor, add 0.1 M hydrochloric acid, adjust the pH value to 4, and stir for 1 hour in a water bath at 20° C. to obtain a precursor solution.

[0082] (2) adding a 4M aqueous solution of sodium hydroxide to the precursor solution, adjusting the pH value of the precursor solution to 14, raising the temperature to 45° C., stirring and reacting for 6 hours under nitrogen protection, and obtaining a modified nano-calcium silicate suspension.

[0083] Example 4 also provides a method for preparing a cement reinforcing additive, wherein the raw materials include the following components: organic component: 18g P1; 111.7g modified nano calcium silicate suspension; initiator: 0.8g azobisisoheptanenitrile. The mass ratio of modified nano calcium silicate to organic component is 0.65:1. The mass ratio of initiator to organic component is 0.04:1.

[0084] The preparation steps of a cement reinforcing additive are as follows: an organic component is mixed with 50g of water to prepare an aqueous solution of the organic component, and then a modified nano calcium silicate suspension is added to the aqueous solution of the organic component as agent A, and an initiator is mixed with 30g of water as agent B. Agents AB are cement reinforcing additives.

[0085] Example 5

[0086] Example 5 provides a method for preparing a modified nano calcium silicate suspension, wherein the raw materials include the following components:

[0087] Calcium source: 3.28g calcium nitrate tetrahydrate; 4g water reducer; silicon source: 2.3g tetramethoxysilane; silane coupling agent: 1g VTES; 100g water. The molar ratio of calcium source to silicon source is 0.9:1. The mass ratio of water reducer to calcium source is 1.2:1. The mass ratio of silane coupling agent to silicon source is 0.4:1.

[0088] The preparation steps of a modified nano calcium silicate suspension are as follows:

[0089] (1) Add a calcium source, a silicon source, a silane coupling agent, a water reducing agent and water into a reactor, add 0.1 M hydrochloric acid, adjust the pH value to 7, stir for 1 hour in a water bath at 40° C. under nitrogen protection, and obtain a precursor solution.

[0090] (2) Add 4M sodium hydroxide aqueous solution to the precursor solution, adjust the pH value of the precursor solution to 10, raise the temperature to 65° C., and stir the reaction for 6 hours to obtain a modified nano-calcium silicate suspension.

[0091] Example 5 also provides a method for preparing a cement reinforcing additive, wherein the raw materials include the following components: organic component: 9g P2; 104.8g modified nano calcium silicate suspension; initiator: 0.3g azobisisobutyl cyanide. The mass ratio of modified nano calcium silicate to organic component is 0.53:1. The mass ratio of initiator to organic component is 0.03:1.

[0092] The preparation steps of a cement reinforcing additive are as follows: an organic component is mixed with 105g of water to prepare an aqueous solution of the organic component, and then a modified nano calcium silicate suspension is added to the aqueous solution of the organic component as agent A, and an initiator is mixed with 30g of water as agent B. Agents AB are cement reinforcing additives.

[0093] Example 6

[0094] Example 6 provides a method for preparing a modified nano calcium silicate suspension, wherein the raw materials include the following components:

[0095] Calcium source: 8g calcium chloride; 4g water reducer; silicon source: 4.6g tetraethoxysilane; silane coupling agent: 1.6g AAPTES; 100g water. The molar ratio of calcium source to silicon source is 3.3:1. The mass ratio of water reducer to calcium source is 0.5:1. The mass ratio of silane coupling agent to silicon source is 0.3:1.

[0096] The preparation steps of a modified nano calcium silicate suspension are as follows:

[0097] (1) Add a calcium source, a silicon source, a silane coupling agent, a water reducing agent and water into a reactor, add 0.1 M hydrochloric acid, adjust the pH value to 4, and stir for 0.2 hours in a water bath at 70° C. to obtain a precursor solution.

[0098] (2) 4 M sodium hydroxide was added to the precursor solution, the pH value of the precursor solution was adjusted to 14, the temperature was raised to 90° C., and the mixture was stirred for 5 hours under nitrogen protection to obtain a modified nano-calcium silicate suspension.

[0099] Example 6 also provides a method for preparing a cement reinforcing additive, wherein the raw materials include the following components: organic component: 9g P4; 110.84g modified nano calcium silicate suspension; initiator: 0.09g dimethyl azobisisobutyrate. The mass ratio of modified nano calcium silicate to organic component is 1.20:1. The mass ratio of initiator to organic component is 0.01:1.

[0100] The preparation steps of a cement reinforcing additive are as follows: an organic component is mixed with 105g of water to prepare an aqueous solution of the organic component, and then modified nano calcium silicate is added to the aqueous solution of the organic component as agent A, and an initiator is mixed with 30g of water as agent B. Agents AB are cement reinforcing additives.

[0101] Example 7

[0102] Example 7 provides a method for preparing a modified nano calcium silicate suspension, wherein the raw materials include the following components:

[0103] Calcium source: 4g calcium chloride; 4g water reducer; silicon source: 4.6g tetraethoxysilane; silane coupling agent: 1.6g AAMTMS; 100g water. The molar ratio of calcium source to silicon source is 1.6:1. The mass ratio of water reducer to calcium source is 1:1. The mass ratio of silane coupling agent to silicon source is 0.3:1.

[0104] The preparation steps of a modified nano calcium silicate suspension are as follows:

[0105] (1) Add a calcium source, a silicon source, a silane coupling agent, a water reducing agent and water into a reactor, add 0.1 M hydrochloric acid, adjust the pH value to 4, stir for 0.2 hours in a water bath at 40° C., and obtain a precursor solution.

[0106] (2) 4 M sodium hydroxide was added to the precursor solution, the pH value of the precursor solution was adjusted to 11, the temperature was raised to 90° C., and the mixture was stirred for reaction for 5 hours under nitrogen protection to obtain a modified nano-calcium silicate suspension.

[0107] Example 7 also provides a method for preparing a cement reinforcing additive, wherein the raw materials include the following components: organic component: 9g P1; 107.4g modified nano calcium silicate suspension; initiator: 0.09g ammonium persulfate. The mass ratio of modified nano calcium silicate to organic component is 0.82:1. The mass ratio of initiator to organic component is 0.01:1.

[0108] The preparation steps of a cement reinforcing additive are as follows: an organic component is mixed with 105g of water to prepare an aqueous solution of the organic component, and then a modified nano calcium silicate suspension is added to the aqueous solution of the organic component as agent A, and an initiator is mixed with 30g of water as agent B. Agents AB are cement reinforcing additives.

[0109] Example 8

[0110] Example 8 provides a method for preparing a modified nano calcium silicate suspension, wherein the raw materials include the following components:

[0111] Calcium source: 4g calcium chloride; 4g water reducer; silicon source: 3g trimethoxysilane; silane coupling agent: 3g AAPTES; 100g water. The molar ratio of calcium source to silicon source is 1.5:1. The mass ratio of water reducer to calcium source is 1:1. The mass ratio of silane coupling agent to silicon source is 1:1.

[0112] The preparation steps of a modified nano calcium silicate suspension are as follows:

[0113] (1) Add a calcium source, a silicon source, a silane coupling agent, a water reducing agent and water into a reactor, add 0.1 M hydrochloric acid, adjust the pH value to 4, and stir for 3 hours in a water bath at 20° C. to obtain a precursor solution.

[0114] (2) 4 M sodium hydroxide was added to the precursor solution, the pH value of the precursor solution was adjusted to 13, the temperature was raised to 30° C., and the reaction was stirred for 12 hours under nitrogen protection to obtain a modified nano-calcium silicate suspension.

[0115] Example 8 also provides a method for preparing a cement reinforcing additive, wherein the raw materials include the following components: organic component: 9g P8; 106.02g modified nano calcium silicate; initiator: 0.2g sodium persulfate and 0.2g triethanolamine. The mass ratio of modified nano calcium silicate to organic component is 0.67:1. The mass ratio of initiator to organic component is 0.04:1.

[0116] The preparation steps of a cement reinforcing additive are as follows: an organic component is mixed with 105g of water to prepare an aqueous solution of the organic component, and then a modified nano calcium silicate suspension is added to the aqueous solution of the organic component as agent A, and an initiator is mixed with 30g of water as agent B. Agents AB are cement reinforcing additives.

[0117] Example 9

[0118] Example 9 provides a method for preparing a modified nano-silicon dioxide suspension, wherein the raw materials include the following components:

[0119] 0.5g water reducer; 10g tetraethoxysilane; 2.5g AAPTMS; 30g water. The mass ratio of silane coupling agent to silicon source is 0.25:1.

[0120] A modified nano-silicon dioxide suspension preparation step is:

[0121] (1) Add a silicon source, a silane coupling agent, a water reducing agent and water into a reactor, add ammonia water, and stir for 3 hours in a water bath at 80° C. to obtain a modified silica sol.

[0122] (2) Using deionized water to wash the sample while filtering under reduced pressure, the washed sample is dispersed in deionized water by ultrasonication to obtain a modified nano-silica suspension.

[0123] Example 9 also provides a method for preparing a cement reinforcing additive, wherein the raw materials include the following components: organic component: 9g P8; 45g modified nano-silicon dioxide suspension; initiator: 0.2g sodium persulfate and 0.2g triethanolamine. The mass ratio of modified nano-silicon dioxide to organic component is 0.3:1.

[0124] The preparation steps of a cement reinforcing additive are as follows: an organic component is mixed with 105g of water to prepare an aqueous solution of the organic component, and then a modified nano-silicon dioxide suspension is added to the aqueous solution of the organic component as agent A, and an initiator is mixed with 30g of water as agent B. Agents AB are cement reinforcing additives.

[0125] Example 10

[0126] The difference between Example 10 and Example 3 is that in the preparation process of the modified nano-calcium silicate suspension, the amount of silane coupling agent used is 0.4 g.

[0127] Embodiment 11

[0128] The difference between Example 11 and Example 3 is that the organic component is P3.

[0129] Comparative Example

[0130] Comparative Example 1

[0131] The difference between Comparative Example 1 and Example 1 is that the cement reinforcing additive is only the modified nano-calcium silicate suspension, and the amount of water used in the preparation of the modified nano-calcium silicate suspension is 300 g.

[0132] Comparative Example 2

[0133] The difference between Comparative Example 2 and Example 1 is that the cement reinforcing additive does not include the modified nano calcium silicate suspension.

[0134] Comparative Example 3

[0135] The difference between Comparative Example 3 and Example 1 is that during the preparation of the modified nano-calcium silicate suspension, no silane coupling agent is added, and the amount of water used is 150 g.

[0136] Comparative Example 4

[0137] The difference between Comparative Example 4 and Example 3 is that the preparation steps of a cement reinforcing additive are as follows: 9g of P1, 105.85g of modified nano calcium silicate suspension and 50g of water are mixed, and then 0.2g of azobisisoheptanenitrile and 30g of water are added, and stirred for 5 hours. The solution obtained by mixing is the cement reinforcing additive. The components are the same as those in Example 3.

[0138] Comparative Example 5

[0139] Comparative Example 5 provides a method for preparing a modified nano calcium silicate suspension, wherein the raw materials include the following components:

[0140] Calcium source: 9.2g calcium acetate; 3.68g water reducer; silicon source: 6.5g trimethoxysilane; silane coupling agent: 2.7g MAPTEMSS; 100g water. The molar ratio of calcium source to silicon source is 1.1:1. The mass ratio of water reducer to calcium source is 0.4:1. The mass ratio of silane coupling agent to silicon source is 0.4:1.

[0141] The preparation steps of a modified nano calcium silicate suspension are as follows:

[0142] (1) Add a calcium source, a silicon source, a silane coupling agent, a water reducing agent and water into a reactor, add 0.1 M hydrochloric acid, adjust the pH value to 5, and stir for 3 hours in a water bath at 20° C. to obtain a precursor solution.

[0143] (2) 4 M sodium hydroxide was added to the precursor solution, the pH value of the precursor solution was adjusted to 12, the temperature was raised to 30° C., and the reaction was stirred for 12 hours under nitrogen protection to obtain a modified nano-calcium silicate suspension.

[0144] Comparative Example 5 also provides a method for preparing a cement reinforcing additive, wherein the raw materials include the following components: organic component: 9g P1; 113.5g modified nano calcium silicate suspension; initiator: 0.2g azobisisoheptanenitrile. The mass ratio of modified nano calcium silicate to organic component is 1.5:1. The mass ratio of initiator to organic component is 0.04:1.

[0145] The preparation steps of a cement reinforcing additive are as follows: an organic component is mixed with 50g of water to prepare an aqueous solution of the organic component, and then a modified nano calcium silicate suspension is added to the aqueous solution of the organic component as agent A, and an initiator is mixed with 30g of water as agent B. Agents AB are cement reinforcing additives.

[0146] Performance Testing

[0147] (1) Mechanical properties test of concrete using the reinforcing agents in the examples and comparative examples:

[0148] The mortar was prepared with Onoda P·II·52.5 cement (Jiangnan Onoda Cement Co., Ltd.) and ISO standard sand, with a sand-cement ratio of 3:1 and a water-cement ratio of 0.4. The amount of the reinforcing agent was based on the organic component in the reinforcing agent, and the solid content was calculated based on the cementitious material (unit: mass percentage, bwoc%). The defoamer used was the ordinary PXP-I concrete defoamer sold by Jiangsu Subote New Materials Co., Ltd. The air content of each group of mortar was basically the same by controlling the amount of defoamer. The water reducer used was the ordinary polycarboxylate water reducer PCA-1 sold by Subote. The test process and molding process were carried out in accordance with GB / T17671-1999 GB / T17671-1999 cement mortar strength test method (ISO method). After mixing the sample and the mortar, the slurry was injected into a mold with a specification of 4*4*16cm after stirring for 4 minutes, and the mold was removed after 24 hours. The demoulding specimens were placed under the conditions of 25°C and humidity above 95% for curing. The test results are shown in Table 2 below.

[0149] (2) Test of the fluidity of cement-based materials containing the reinforcing additives of the embodiments or comparative examples: The fluidity test of the cement-based materials was conducted using Onoda P.II52.5 cement with a water-cement ratio of 0.29. The water reducer used was a conventional polycarboxylate water reducer PCA-I commercially available from Subote. The amount of the water reducer added to all samples was 0.04%. The test results are shown in Table 3.

[0150] Table 2 Mechanical properties test table of the embodiments and comparative examples

[0151]

[0152]

[0153] Table 3 Test table of the fluidity of the pure slurry of the embodiment and the comparative example

[0154]

[0155]

[0156] According to the test results of Examples 1-8, the present application can well improve the flexural properties of cement-based materials, so that cement-based materials have both good compressive strength and flexural strength; further analysis of Examples 1-4 shows that the present application can greatly improve the compressive and flexural properties of cement at a relatively low dosage, wherein Example 3 has a 2% dosage, and the 28-day flexural performance is improved by up to 63.74%. In addition, when the dosage is 4%, the 28-day flexural performance is improved by up to 55.75%, and the compressive performance is improved by up to 55.39%. This shows that the present application can better improve the flexural properties of cement-based materials, so that cement-based materials have both good compressive strength and flexural strength.

[0157] Further comparison with Comparative Example 1 and Comparative Example 2 revealed that, whether only the modified nano calcium silicate suspension was used in Comparative Example 1, or only the organic component was used in Comparative Example 2, not only did the performance of the cement not improve well, but even the compressive performance decreased. This shows that in the reinforcing additive of the present application, the inorganic component and the organic component complement each other, and the interlaced network structure formed is distributed in a mesh shape and each part is continuous, which can present a "bundled" state to each part of the cement-based material; and thus the network structure can be distributed more evenly in the cement-based material, and the compatibility and bonding between the gel network and the polymer network, and between the network structure and the cement-based material are more excellent, so that the flexural and compressive properties of the cement-based material can be better improved.

[0158] At the same time, the performance of comparative example 4 was analyzed and it was found that if the reinforcing additive was not used in the manner specified in the present application, even if the same components were used, the performance of cement could not be improved well in the end. It can be proved that the reinforcing additive of the present application can indeed form an interpenetrating network structure in the cement-based material with a mesh distribution and each part in a continuous state, which can present a "bundling" state to each part of the cement-based material and improve the performance of the cement-based material. Further analysis of the performance of comparative example 5 shows that the amount of organic components and modified inorganic components will have a certain influence on the properties of the reinforcing agent.

[0159] Analysis of the performance of Example 10 and Comparative Example 3 revealed that the silane coupling agent is very important for the modification of the modified nano-calcium silicate. On the one hand, the silane coupling agent can cause the modified nano-calcium silicate suspension to be evenly dispersed in the cement-based material, thereby laying the foundation for the subsequent formation of a network structure; on the other hand, the modified nano-calcium silicate obtained after modification with the silane coupling agent can be smoothly combined with the organic component to form a polymer network, and the polymer network can form a network structure with the gel network that is interspersed with each other, distributed in a network, and each part is in a continuous state.

[0160] In addition, the performance of Example 9 was analyzed to find that the modified nano-silicon dioxide suspension and the organic component can also improve the compression and flexural properties of the cement material at a lower dosage. However, in comparison, the modified nano-calcium silicate suspension has a better effect.

[0161] The performance of Example 11 was found to be different from that of Example 3, because the organic component of Example 11 was P3, and the final performance decreased to a certain extent. This may be because the use of acrylic acid affected the hydration of cement.

[0162] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A cement reinforcing additive, Features: The invention is prepared from raw materials including a suspension of a modified inorganic component modified by a silane coupling agent and containing double bonds, an organic component and an initiator, wherein the weight ratio of the organic component to the modified inorganic component modified by a silane coupling agent and containing double bonds is 1:(0.3-1.2); after the modified inorganic component modified by a silane coupling agent and containing double bonds and the suspension of the organic component are added to a cement-based material, the modified inorganic component modified by a silane coupling agent and containing double bonds and hydrated particles in the cement-based material are connected to form a gelling network, the modified inorganic component modified by a silane coupling agent and containing double bonds forms a polymer network with the organic component through the action of double bonds and the action of the initiator, and the gelling network and the polymer network are interspersed with each other and distributed in a network shape.

2. A cement reinforcing additive according to claim 1, Features: The modified inorganic component modified by a silane coupling agent and containing double bonds is a modified nano calcium silicate suspension. The preparation method of the modified nano calcium silicate suspension comprises the following steps: (1) mixing a calcium source, a silicon source, a silane coupling agent, a water reducing agent and water, adjusting the pH value to 4-7, and stirring to obtain a precursor solution; (2) The pH value of the precursor solution is adjusted to 10-14, and the reaction is stirred to obtain a modified nano-calcium silicate suspension.

3. A cement reinforcing additive according to claim 2, Features: In the preparation step (1) of the modified nano-calcium silicate suspension, the stirring temperature is 15-70° C. and the stirring time is 0.2-2 hours.

4. A cement reinforcing additive according to claim 2, Features: In the preparation step (2) of the modified nano-calcium silicate suspension, the stirring temperature is 15-90° C. and the stirring time is 5-15 hours.

5. A cement reinforcing additive according to claim 2, Features: The calcium source is at least one of calcium chloride, calcium nitrate tetrahydrate, calcium hydrogen phosphate, calcium formate and calcium acetate.

6. A cement reinforcing additive according to claim 2, Features: The silicon source is at least one of tetraethoxysilane, tetramethoxysilane, trimethoxysilane and triethoxysilane.

7. A cement reinforcing additive according to claim 2, Features: The ratio of the amount of the calcium source to the amount of the silicon source is (0.9-3.3):

1.

8. A cement reinforcing additive according to claim 1, Features: The mass ratio of the silane coupling agent to the silicon source is (0.3-1):

1.

9. A cement reinforcing additive according to claim 1, Features: The silane coupling agent is at least one of vinyl trimethoxy silane, vinyl triethoxy silane, methacryloxypropyl trimethoxy silane, methacryloxypropyl triethoxy silane, methacryloxymethyl triethoxy silane, acryloxymethyl trimethoxy silane and acryloxypropyl trimethoxy silane.

10. A cement reinforcing additive according to claim 1, Features: The organic component includes at least one of the following components, and the general formula of the organic component is as follows: Where R 1 Indicates H, CH 3 or CH 3 COOH, R 2 Represents H or active metal ions; R 3 Indicates H or CH 3 , R 4 , R 5 H and CH are represented independently 3 , CH 2 CH 3 , CH 2 OH, CH 2 CH 2 OH, CH 2 CHCH 3 OH; R 6 , R 7 and R 8 Each independently represents H or CH 3 , R 9 represents an alkyl group having 4 to 30 carbon atoms; X 1 , X 2 and X 3 Each independently represents O or NH; a and b each independently represent ethoxy -CH 2 CH 2 The average number of repeating units of the O-link, a and b range from 4 to 50.

11. A method for preparing the cement reinforcing additive according to any one of claims 1 to 10, It is characterized in that The following steps are involved: Organic components and water are added to the modified nano calcium silicate suspension as agent A, and an initiator solution is added as agent B. Agents AB are cement reinforcing additives.

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