A cement enhancing additive and a method of making the same

Abstract

The application relates to the field of building materials, and particularly discloses a cement reinforcing additive and a preparation method thereof, wherein the 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; the weight ratio of the organic component to the modified inorganic component modified by the silane coupling agent and containing the double bonds is 1:(0.3-1.2); after the modified inorganic component suspension modified by the silane coupling agent and containing the double bonds and the organic component are added into a cement-based material, the cementing network and the polymer network are interpenetrated and distributed in a net shape. The application can better improve the bending resistance of the cement-based material, so that the cement-based material has good compressive strength and bending strength.

Description

Technical Field

[0001] This application relates to the field of building materials, and more specifically, to a cement reinforcing additive and a method for preparing the same. Background Technology

[0002] Cement-based composite materials have become a major building material worldwide due to their abundant raw materials, low cost, high strength, and simple production process, and are widely used in large-scale projects such as civil buildings, roads, bridges, airports, ports, and water conservancy. However, cement-based composite materials are inhomogeneous, porous, and brittle materials. When subjected to external loads, stress initially concentrates at defects. Nanocracks are generated at the loosely accumulated hydration products and gradually propagate into micron-sized cracks. Under continuous load, these micron-sized cracks continue to expand and merge, forming macroscopic cracks, ultimately leading to brittle fracture of the material. The presence of pores and cracks not only reduces the strength of cement-based composite materials but also induces problems such as infiltration. The intrusion of harmful ions reduces the durability of cement-based composite materials, increases maintenance costs, and shortens their service life. Therefore, strengthening cement-based composite materials has become one of the current research hotspots.

[0003] Studies have shown that by introducing high-toughness materials, fibers and polymer emulsions are two of the most researched and widely used materials. However, fibers are unevenly dispersed during concrete mixing, easily agglomerating, resulting in poor workability and pumping difficulties. Furthermore, since fiber toughening in concrete mainly relies on the pull-in effect to limit crack propagation, the performance of fiber-modified concrete is closely related to fiber dispersion and orientation. Therefore, the stability of fiber-modified concrete is difficult to control, requiring careful attention to various aspects in practical applications. Improving the flexural strength of polymer emulsion-modified concrete often comes at the expense of the compressive strength of cement-based materials. For example, in the 2019 work reported by Farshad Farshchi Tabrizi, SBA-modified concrete improved flexural strength by 22.6%, but compressive strength decreased significantly. This decrease is mainly due to the lack of activity of traditional additives like fibers and polymer emulsions; they neither participate in the hydration reaction nor promote the hydration process. Their role is primarily physical, and their effect in concrete depends only on their own physical properties, without modifying the concrete's microstructure.

[0004] Chinese Patent Publication No. CN111517703A discloses a high flexural strength cement-based material and its preparation method, relating to the field of concrete technology. The high flexural strength cement-based material includes cement hydrate and a polymer chemically bonded to the cement hydrate. The polymer is obtained by in-situ polymerization of monomers in cement under the action of an initiator and an accelerator. The preparation method of the high flexural strength cement-based material involves mixing and dissolving the monomers, initiator, and accelerator, and then performing in-situ polymerization in cement. The resulting polymer and cement hydrate are linked by chemical bonds, effectively improving the flexural strength of the cement-based material. However, in this method, the organic and inorganic components are mainly separated by -COOH and Ca in the cement. 2+ The weak hydrogen bond interaction results in limited actual binding effect.

[0005] Chinese patent CN115368106A discloses a high-strength cement concrete and its preparation method, belonging to the field of building materials technology. Through modification treatment, a hyperbranched structure can be formed on the surface of ultra-short steel fibers, significantly increasing the surface roughness of the fibers and greatly improving interfacial friction, physical adsorption, and chemical bond strength. This solves the technical problem of poor toughness in cement concrete, achieving a balance and unity between high strength and high toughness. However, it still does not address the fundamental issue of poor concrete workability caused by the introduction of fibers.

[0006] Chinese Patent CN105713125B discloses an organic-inorganic hybrid particle, its preparation method, and its application in the modification of cement-based materials, belonging to the field of admixtures for modifying cement-based materials. By preparing organic-inorganic hybrid particles as a reinforcing agent, the organic and inorganic components are interconnected by covalent bonds, not in a core-shell structure, but rather interpenetrating and linked by covalent chemical bonds. Siloxane D is the main source of the inorganic component in the organic-inorganic hybrid particles. The aqueous dispersion of these organic-inorganic hybrid particles, as a reinforcing agent for cement-based materials, can simultaneously improve the compressive, flexural, and tensile (or splitting) strength of cement-based materials.

[0007] Although the organic and inorganic phases in the aforementioned organic-inorganic hybrid particles are covalently bonded, which is beneficial for their stable dispersion and can effectively improve the compressive strength of cement-based materials, the improvement of cement material performance by these hybrid particles mainly relies on the promoting effect of the inorganic component on hydration. The organic component merely provides spatial repulsion between the inorganic nanoparticles to ensure better dispersion of the inorganic component, and does not fully leverage the enhancing effect of the organic component on toughness. Summary of the Invention

[0008] In order to improve the flexural strength of cement-based materials and enable them to have both good flexural and compressive strength, this application provides a cement reinforcing additive and its preparation method.

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

[0010] A cement reinforcing additive is prepared from raw materials including a suspension of modified inorganic components containing double bonds modified by a silane coupling agent, an organic component, and an initiator. The weight ratio of the organic component to the modified inorganic component containing double bonds modified by the silane coupling agent is 1:(0.3-1.2). After the suspension of the modified inorganic component containing double bonds modified by the silane coupling agent and the organic component is added to a cement-based material, the modified inorganic component containing double bonds modified by the silane coupling agent and the hydrated particles in the cement-based material are connected to form a cementitious network. The modified inorganic component containing double bonds modified by the silane coupling agent and the organic component form a polymer network through double bond interaction and initiator interaction. The cementitious network and the polymer network interweave and are distributed in a mesh-like manner.

[0011] By adopting the above technical solution, firstly, the modified inorganic component suspension and the organic component are added to the cement-based material separately along with the initiator. The modified inorganic component suspension, which is modified by the silane coupling agent and contains double bonds, can be uniformly dispersed in the cement-based material. Moreover, in the cement-based material, the modified inorganic component and the hydrated particles in the cement-based material are connected to form a gel network. The double bonds on the organic component and the modified inorganic component can undergo in-situ polymerization under the action of the initiator to form a polymer network, thereby constituting an interpenetrating network structure and a mesh-like distribution. Furthermore, in addition to connecting the network structure with the cementitious material through linkage with hydrated particles, this application also forms an interwoven network structure that is distributed in a mesh-like pattern within the cementitious material. The various parts of the network structure are continuous, effectively "binding" the different parts of the cementitious material. Compared to the relatively independent and dispersed network structures formed in existing technologies, the network structure of this application is more uniformly distributed within the cementitious material. Moreover, the compatibility and bonding between the gel network and the polymer network, and between the network structure and the cementitious material, are superior, thus better improving the flexural strength of the cementitious material. Simultaneously, the formation process of the network structure in this application occurs simultaneously with the hydration process of the cementitious material, having almost no impact on hydration, not delaying cement hydration, and not negatively affecting the compressive strength of the cementitious material; in fact, it can further improve the compressive strength of the cementitious material. Therefore, this application can better improve the flexural strength of cementitious materials, enabling them to possess both good compressive and flexural strength.

[0012] Furthermore, the modified inorganic component modified with 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 includes the following steps:

[0013] (1) Mix calcium source, silicon source, silane coupling agent, water reducing agent and water, adjust the pH value to 4-7, and stir to obtain precursor solution;

[0014] (2) Adjust the pH of the precursor solution to 10-14 and stir the reaction to obtain a modified nano-calcium silicate suspension.

[0015] By adopting the above technical solution, this application first prepares a stable modified nano-calcium silicate suspension, which can not only be uniformly dispersed in cement-based materials, but also more stably connects with the hydrated particles in the cement-based materials to form a cementitious network. Simultaneously, it more stably polymerizes with organic components in situ under the action of an initiator to form a polymer network, constituting an interwoven network structure with a mesh-like distribution. This can better improve the flexural strength of cement-based materials, enabling them to possess both good compressive and flexural strength.

[0016] Further, in step (1) of preparing the modified nano-calcium silicate suspension, the stirring temperature is 15-70℃ and the stirring time is 0.2-2 hours. In step (2) of preparing the modified nano-calcium silicate suspension, the stirring temperature is 15-90℃ and the stirring time is 5-15 hours. Further still, 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 molar ratio 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-reducing agent is a polycarboxylate water-reducing agent, and the mass ratio of the water-reducing agent to the calcium source is (0.2-3):1.

[0017] By adopting the above technical solutions and optimizing the preparation conditions and raw material ratio of the modified nano-calcium silicate suspension, it is beneficial to form a more stable modified nano-calcium silicate suspension, which in turn is 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, methacryloyloxypropyltrimethoxysilane, methacryloyloxypropyltriethoxysilane, methacryloyloxymethyltriethoxysilane, acryloyloxymethyltrimethoxysilane, and acryloyloxypropyltrimethoxysilane.

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

[0020]

[0021] Where R1 represents H, CH3, or CH3COOH, R2 represents H or an active metal ion; R3 represents H or CH3; R4 and R5 independently represent H, CH3, CH2CH3, CH2OH, CH2CH2OH, and CH2CHCH3OH, respectively; R6, R7, and R8 independently represent H or CH3, respectively; R9 represents an alkyl group with 4-30 carbon atoms; X1, X2, and X3 independently represent O or NH, respectively; a and b independently refer to the average repeating unit number of the ethoxy-CH2CH2O- chain segment, with values ​​ranging 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 solutions and optimizing the preparation conditions and raw material ratio of the modified nano-calcium silicate suspension, it is beneficial to form a more stable modified nano-calcium silicate suspension, which in turn is more conducive to forming a stable network structure and better improving the performance of cement-based materials.

[0024] Secondly, this application provides a method for preparing a cement reinforcing additive, which adopts the following technical solution:

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

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

[0027] 1. In the reinforcing additive system of this application, the modified inorganic components, organic components, and water-based materials can form an interwoven network structure and be distributed in a mesh-like manner. The various parts of this network structure are continuous, therefore, compared to the conventional independent and dispersed network structures formed in cement systems, the network structure of this application can "bundle" the various parts of the cement-based material. The network structure of this application can be more uniformly distributed 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 superior, thereby better improving the flexural strength of the cement-based material.

[0028] 2. The construction process of the network structure in this application and the hydration process of the cement-based material occur simultaneously. It has almost no impact on the hydration, does not delay the hydration of cement, does not have a negative impact on the compressive strength of the cement-based material, and can further improve the compressive strength of the cement-based material.

[0029] 3. Compared to traditional methods of directly adding polymer emulsions or fibers, this method requires less organic component and has no negative impact on the workability of cement-based materials; in fact, it may even improve workability under certain conditions. Compared to traditional methods of adding inorganic or hybrid nanoparticles, this method can more effectively utilize the role of nanoparticles in cement-based materials, acting as a bridging agent to connect hydration products and organic components, thereby effectively improving flexural strength. Detailed Implementation

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

[0031] Example

[0032] This embodiment provides a cement reinforcing additive, prepared from raw materials including a suspension of modified inorganic components containing double bonds modified with a silane coupling agent, an organic component, and an initiator. The preparation method of the cement reinforcing additive is as follows: an organic component and water are added to the suspension of modified inorganic components containing double bonds as agent A, and an initiator solution is added as agent B. Agents A and B together constitute the cement reinforcing additive.

[0033] The weight ratio of the organic component to the modified inorganic component containing double bonds modified by the silane coupling agent is 1:(0.3-1.2); the amount of 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 specific embodiments, the intermediate-temperature thermal initiator includes one of azobisisobutyronitrile, azobisisobutyronitrile, azobisisoheptanenitrile, 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 structures of the organic components are shown in Table 1.

[0036] Table 1. Material Structure of Organic Components

[0037]

[0038]

[0039] In this embodiment, the modified inorganic component suspension is a modified nano-calcium silicate suspension or a modified nano-silica suspension. In the cement reinforcing additive of this 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 cementitious network. The modified inorganic component forms a polymer network with the organic component through double bond interactions and initiator interactions. The cementitious network and the polymer network interpenetrate each other and are distributed in a mesh-like manner.

[0040] The embodiments of this application provide a method for preparing a modified nano-calcium silicate suspension, comprising the following steps:

[0041] (1) Mix calcium source, silicon source, silane coupling agent, water reducing agent and water, adjust the pH value to 4-7, and stir to obtain precursor solution;

[0042] (2) Adjust the pH of the precursor solution to 10-14 and stir the reaction to obtain a modified nano-calcium silicate suspension.

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

[0044] Furthermore, in step (2) of preparing the modified nano-calcium silicate suspension, the stirring temperature is 15-90℃ 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 molar ratio of calcium source to silicon source is (0.9-3.3):1.

[0048] The silane coupling agent is at least one of vinyltrimethoxysilane (VMES), vinyltriethoxysilane (VTES), methacryloyloxypropyltrimethoxysilane (MAPTMS), methacryloyloxypropyltriethoxysilane (MAPTES), methacryloyloxymethyltriethoxysilane (AAPTES), acryloyloxymethyltrimethoxysilane (AAMTMS), and acryloyloxypropyltrimethoxysilane (AAPTMS).

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

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

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

[0052] The following is an illustration 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-reducing agent; 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-reducing agent 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 calcium source, silicon source, silane coupling agent, water reducing agent and water to the reactor, add 0.1M hydrochloric acid, adjust the pH value to 4, stir for 1 hour under water bath conditions of 20℃ to obtain precursor solution.

[0058] (2) Add 4M sodium hydroxide aqueous solution to the precursor solution to adjust the pH value of the precursor solution to 14, raise the temperature to 45℃, and stir the reaction for 6 hours under nitrogen protection to obtain 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 azobisisobutyronitrile. 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: mix organic components with 50g of water to prepare an aqueous solution of organic components, then add modified nano-calcium silicate suspension to the aqueous solution of organic components as agent A, and mix initiator with 30g of water as agent B. Agents A and B are the cement reinforcing additive.

[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-reducing agent; 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-reducing agent 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 calcium source, silicon source, silane coupling agent, water reducing agent and water to the reactor, add 0.1M hydrochloric acid, adjust the pH value to 4, stir for 3 hours under water bath conditions at 20℃ to obtain precursor solution.

[0066] (2) Add 4M sodium hydroxide to the precursor solution to adjust the pH value of the precursor solution to 14, raise the temperature to 30°C, and stir the reaction for 12 hours under nitrogen protection to obtain 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: 4.5g P1; 102.92g modified nano-calcium silicate suspension; initiator: 0.2g azobisisobutyronitrile. 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: mix organic components with 50g of water to prepare an aqueous solution of organic components, mix the aqueous solution of organic components with modified nano-calcium silicate suspension as agent A, and mix initiator with 30g of water as agent B. Agents A and B are the cement reinforcing additive.

[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-reducing agent; 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-reducing agent 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 calcium source, silicon source, silane coupling agent, water reducing agent and water to the reactor, add 0.1M hydrochloric acid, adjust the pH value to 5, stir for 3 hours under water bath conditions at 20℃ to obtain precursor solution.

[0074] (2) Add 4M sodium hydroxide to the precursor solution to adjust the pH value of the precursor solution to 12, raise the temperature to 30°C, and stir the reaction for 12 hours under nitrogen protection to obtain 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 azobisisobutyronitrile. 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: mix organic components with 50g of water to prepare an aqueous solution of organic components, then add modified nano-calcium silicate suspension to the aqueous solution of organic components as agent A, and mix initiator with 30g of water as agent B. Agents A and B are the cement reinforcing additive.

[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-reducing agent; 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-reducing agent 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 calcium source, silicon source, silane coupling agent, water reducing agent and water to the reactor, add 0.1M hydrochloric acid, adjust the pH value to 4, stir for 1 hour under water bath conditions of 20℃ to obtain precursor solution.

[0082] (2) Add 4M sodium hydroxide aqueous solution to the precursor solution to adjust the pH value of the precursor solution to 14, raise the temperature to 45℃, and stir the reaction for 6 hours under nitrogen protection to obtain 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 azobisisobutyronitrile. 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: mix organic components with 50g of water to prepare an aqueous solution of organic components, then add modified nano-calcium silicate suspension to the aqueous solution of organic components as agent A, and mix initiator with 30g of water as agent B. Agents A and B are the cement reinforcing additive.

[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-reducing agent; 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-reducing agent 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 calcium source, silicon source, silane coupling agent, water reducing agent and water to the reactor, add 0.1M hydrochloric acid, adjust the pH value to 7, stir for 1 hour under nitrogen protection in a water bath at 40℃ to obtain the precursor solution.

[0090] (2) Add 4M sodium hydroxide aqueous solution to the precursor solution, adjust the pH value of the precursor solution to 10, heat to 65℃, stir for 6 hours to obtain 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 azobisisobutyronitrile. 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: mix the organic component with 105g of water to prepare an aqueous solution of the organic component, then add the modified nano-calcium silicate suspension to the aqueous solution of the organic component as agent A, and mix the initiator with 30g of water as agent B. Agents A and B are the cement reinforcing additive.

[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-reducing agent; 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-reducing agent 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 calcium source, silicon source, silane coupling agent, water reducing agent and water to the reactor, add 0.1M hydrochloric acid, adjust the pH value to 4, stir for 0.2 hours under water bath conditions of 70℃ to obtain precursor solution.

[0098] (2) Add 4M sodium hydroxide to the precursor solution to adjust the pH value of the precursor solution to 14, heat to 90℃, and stir for 5 hours under nitrogen protection to obtain 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: mix the organic component with 105g of water to prepare an aqueous solution of the organic component, then add the modified nano-calcium silicate to the aqueous solution of the organic component as agent A, and mix the initiator with 30g of water as agent B. Agents A and B are the cement reinforcing additive.

[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-reducing agent; 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-reducing agent 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 calcium source, silicon source, silane coupling agent, water reducing agent and water to the reactor, add 0.1M hydrochloric acid, adjust the pH value to 4, stir for 0.2 hours under water bath conditions of 40℃ to obtain precursor solution.

[0106] (2) Add 4M sodium hydroxide to the precursor solution to adjust the pH value of the precursor solution to 11, raise the temperature to 90℃, and stir the 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: mix the organic component with 105g of water to prepare an aqueous solution of the organic component, then add the modified nano-calcium silicate suspension to the aqueous solution of the organic component as agent A, and mix the initiator with 30g of water as agent B. Agents A and B are the cement reinforcing additive.

[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-reducing agent; 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-reducing agent 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 calcium source, silicon source, silane coupling agent, water reducing agent and water to the reactor, add 0.1M hydrochloric acid, adjust the pH value to 4, stir for 3 hours under water bath conditions at 20℃ to obtain precursor solution.

[0114] (2) Add 4M sodium hydroxide to the precursor solution to adjust the pH value of the precursor solution to 13, raise the temperature to 30°C, and stir the reaction for 12 hours under nitrogen protection to obtain 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: mix the organic component with 105g of water to prepare an aqueous solution of the organic component, then add the modified nano-calcium silicate suspension to the aqueous solution of the organic component as agent A, and mix the initiator with 30g of water as agent B. Agents A and B are the cement reinforcing additive.

[0117] Example 9

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

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

[0120] The preparation steps of a modified nano-silica suspension are as follows:

[0121] (1) Add silicon source, silane coupling agent, water reducing agent and water to the reactor, add ammonia water, stir for 3 hours under water bath conditions of 80℃ to obtain modified silica sol.

[0122] (2) The sample was washed with deionized water while being filtered under reduced pressure. The washed sample was then dispersed in deionized water by ultrasound 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-silica suspension; initiator: 0.2g sodium persulfate and 0.2g triethanolamine. The mass ratio of modified nano-silica to organic component is 0.3:1.

[0124] The preparation steps of a cement reinforcing additive are as follows: mix the organic component with 105g of water to prepare an aqueous solution of the organic component, then add the modified nano silica suspension to the aqueous solution of the organic component as agent A, and mix the initiator with 30g of water as agent B. Agents A and B are the cement reinforcing additive.

[0125] Example 10

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

[0127] Example 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 a modified nano-calcium silicate suspension, and the amount of water used in the preparation of the modified nano-calcium silicate suspension is 300g.

[0132] Comparative Example 2

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

[0134] Comparative Example 3

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

[0136] Comparative Example 4

[0137] The difference between Comparative Example 4 and Example 3 lies in the following steps: The preparation of a cement reinforcing additive involves mixing 9g of P1, 105.85g of modified nano-calcium silicate suspension, and 50g of water, then adding 0.2g of azobisisobutyronitrile and 30g of water, and stirring for 5 hours. The resulting solution is the cement reinforcing additive. All components are the same as 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-reducing agent; 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-reducing agent 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 calcium source, silicon source, silane coupling agent, water reducing agent and water to the reactor, add 0.1M hydrochloric acid, adjust the pH value to 5, stir for 3 hours under water bath conditions at 20℃ to obtain precursor solution.

[0143] (2) Add 4M sodium hydroxide to the precursor solution to adjust the pH value of the precursor solution to 12, raise the temperature to 30°C, and stir the reaction for 12 hours under nitrogen protection to obtain 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 azobisisobutyronitrile. 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: mix organic components with 50g of water to prepare an aqueous solution of organic components, then add modified nano-calcium silicate suspension to the aqueous solution of organic components as agent A, and mix initiator with 30g of water as agent B. Agents A and B are the cement reinforcing additive.

[0146] Performance testing

[0147] (1) Mechanical property testing of concrete with reinforcing agents in the application examples and comparative examples:

[0148] The mortar was prepared using Onoda P·II·52.5 cement (Jiangnan Onoda Cement Co., Ltd.) and ISO standard sand, with a sand-to-cement ratio of 3:1 and a water-to-cement ratio of 0.4. The amount of reinforcing agent was based on the organic component in the reinforcing agent, calculated based on the refractory weight of the cementitious material (unit: mass percentage, bwoc%). The defoamer used was the commercially available PXP-I concrete defoamer from Jiangsu Subote New Material Co., Ltd. The air content of each group of mortars was kept basically consistent by controlling the amount of defoamer used. The water-reducing agent used was the commercially available polycarboxylate superplasticizer PCA-1 from Subote. The testing and molding process was carried out in accordance with GB / T17671-1999 GB / T17671-1999 Cement Mortar Strength Test Method (ISO Method). After mixing the sample and adhesive, the slurry was poured into a mold with a size of 4*4*16cm after stirring for 4 minutes. The mold was removed after 24 hours. The demolded specimens were cured at 25℃ and above 95% humidity. The test results are shown in Table 2 below.

[0149] (2) Flowability test of cementitious paste containing reinforcing additives from the examples or comparative examples: The flowability test of the cement paste used Onoda P·II 52.5 cement with a water-cement ratio of 0.29. The water-reducing agent used was the commercially available polycarboxylate superplasticizer PCA-I from Subote Company. The amount of water-reducing agent added in all samples was 0.04%. The test results are shown in Table 3.

[0150] Table 2 Mechanical property test results for the embodiments and comparative examples

[0151]

[0152]

[0153] Table 3. Flour Detection Table for Neat Paste in Examples and Comparative Examples

[0154]

[0155]

[0156] According to the test results of Examples 1-8, this application can effectively improve the flexural properties of cement-based materials, enabling them to possess both good compressive and flexural strength. Further analysis of Examples 1-4 shows that this application can significantly improve the compressive and flexural properties of cement even at low dosages. In Example 3, with a dosage of 2%, the 28-day flexural properties improved by as much as 63.74%. Furthermore, when the dosage is 4%, the 28-day flexural properties improved by as much as 55.75%, while the compressive properties improved by as much as 55.39%. This demonstrates that this application can better improve the flexural properties of cement-based materials, enabling them to possess both good compressive and flexural strength.

[0157] Further comparison with Comparative Examples 1 and 2 revealed that neither Comparative Example 1, which used only modified nano-calcium silicate suspension, nor Comparative Example 2, which used only organic components, ultimately improved the performance of cement effectively; in fact, the compressive strength decreased. This indicates that in the reinforcing additive of this application, the inorganic and organic components complement each other, forming an interwoven network structure with a continuous distribution, which can "bind" the various parts of the cement-based material. Consequently, the network structure can be more uniformly distributed in the cement-based material, and the compatibility and bonding between the gel network and the polymer network, as well as between the network structure and the cement-based material, are superior, thus better improving the flexural and compressive strength of the cement-based material.

[0158] Simultaneous analysis of the performance of Comparative Example 4 revealed that if the reinforcing additive was not used in accordance with the method specified in this application, even with the same components, the performance of the cement could not be significantly improved. This demonstrates that the reinforcing additive of this application can indeed form an interwoven network structure in cement-based materials, with each part in a continuous state, effectively "binding" the various parts of the cement-based material and improving its performance. Further analysis of the performance of Comparative Example 5 revealed that the amount of organic and modified inorganic components has a certain impact on the properties of the reinforcing agent.

[0159] Analysis of the performance of Example 10 and Comparative Example 3 revealed that silane coupling agents are crucial for the modification of nano-calcium silicate. On the one hand, silane coupling agents can promote the uniform dispersion of modified nano-calcium silicate suspension in cement-based materials, thus laying the foundation for the subsequent formation of network structures. On the other hand, the modified nano-calcium silicate obtained after modification with silane coupling agents can successfully combine with organic components to form a polymer network. At the same time, the polymer network can form an interpenetrating, mesh-like network structure with continuous parts with the gel network.

[0160] Furthermore, analysis of the performance of Example 9 revealed that the modified nano-silica suspension, when combined with organic components, can also effectively improve the compressive and flexural properties of cement materials at a relatively low dosage. However, the modified nano-calcium silicate suspension showed a more superior effect.

[0161] Regarding the performance of Example 11, compared with Example 3, the organic component used in Example 11 is P3, and the final performance has decreased to a certain extent. This may be because the use of acrylic acid affects the hydration of cement.

[0162] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A cement reinforcing additive, characterized in that: The material is prepared from raw materials including a suspension of modified inorganic components containing double bonds modified with silane coupling agent, an organic component, and an initiator. The weight ratio of the organic component to the modified inorganic component containing double bonds modified with silane coupling agent is 1:(0.3-1.2). After the suspension of the modified inorganic component containing double bonds modified with silane coupling agent and the organic component is added to the cement-based material, the modified inorganic component containing double bonds modified with silane coupling agent and the hydrated particles in the cement-based material are connected to form a gel network. The modified inorganic component containing double bonds modified with silane coupling agent and the organic component form a polymer network through double bond interaction and initiator interaction. The gel network and the polymer network interweave with each other and are distributed in a mesh-like pattern. The modified inorganic component, modified with 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 includes the following steps: (1) Mix calcium source, silicon source, silane coupling agent, water reducing agent and water, adjust the pH value to 4-7, and stir to obtain precursor solution; (2) Adjust the pH of the precursor solution to 10-14 and stir the reaction to obtain a modified nano-calcium silicate suspension; The organic component includes at least one of the following components, and the general formula of the organic component is as follows: Where R1 represents H, CH3, or CH3COOH, R2 represents H or an active metal ion; R3 represents H or CH3; R4 and R5 independently represent H, CH3, CH2CH3, CH2OH, CH2CH2OH, and CH2CHCH3OH, respectively; R6, R7, and R8 independently represent H or CH3, respectively; R9 represents an alkyl group with 4-30 carbon atoms; X1, X2, and X3 independently represent O or NH, respectively; a and b independently refer to the average repeating unit number of the ethoxy-CH2CH2O- chain segment, with values ​​ranging from 4 to 50; In this process, 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 A and B are cement reinforcing additives.

2. The cement reinforcing additive according to claim 1, characterized in that: In step (1) of the preparation of the modified nano-calcium silicate suspension, the stirring temperature is 15-70℃ and the stirring time is 0.2-2 hours.

3. The cement reinforcing additive according to claim 1, characterized in that: In step (2) of the preparation of the modified nano-calcium silicate suspension, the stirring temperature is 15-90℃ and the stirring time is 5-15 hours.

4. The cement reinforcing additive according to claim 1, characterized in that: The calcium source is at least one of calcium chloride, calcium nitrate tetrahydrate, calcium hydrogen phosphate, calcium formate, and calcium acetate.

5. A cement reinforcing additive according to claim 1, characterized in that: The silicon source is at least one of tetraethoxysilane, tetramethoxysilane, trimethoxysilane, and triethoxysilane.

6. The cement reinforcing additive according to claim 1, characterized in that: The molar ratio of the calcium source to the silicon source is (0.9-3.3):

1.

7. The cement reinforcing additive according to claim 1, characterized in that: The mass ratio of the silane coupling agent to the silicon source is (0.3-1):

1.

8. The cement reinforcing additive according to claim 1, characterized in that: The silane coupling agent is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, methacryloyloxypropyltrimethoxysilane, methacryloyloxypropyltriethoxysilane, methacryloyloxymethyltriethoxysilane, acryloyloxymethyltrimethoxysilane, and acryloyloxypropyltrimethoxysilane.

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