Calcium silicate hydrate based on co-modification of linear silane and amino acid and preparation method thereof

Abstract

This invention discloses a modified calcium silicate hydrate based on linear silanes and amino acids, and its preparation method. The modified calcium silicate hydrate is composed of the following raw materials: 99.81%-99.95% calcium silicate hydrate raw material, 0.05%-0.19% linear silane, and 0.02%-0.11% polar positively charged amino acids, accounting for 0.02%-0.11% of the total amount of calcium silicate hydrate raw material and linear silane. In the preparation process, the polar positively charged amino acids are first dissolved in deionized water, the pH value is adjusted, and linear silane and ethanol are added. The mixture reacts to obtain a mixed solution A. Then, an anhydrous calcium chloride solution is prepared and mixed solution A is added to obtain mixed solution B. Finally, a sodium silicate nonahydrate solution containing sodium hydroxide is prepared, and mixed solution B is added dropwise to the sodium silicate nonahydrate solution containing sodium hydroxide. After reaction, washing, and drying, the modified calcium silicate hydrate is obtained. The modified calcium silicate of the present invention uses amino acids and linear silanes to jointly modify calcium silicate hydrate. Based on the synergistic effect of the two, it can promote the formation of an ordered stacked thin film of calcium silicate hydrate and tend to develop into an ordered parallel stacked layered structure, thereby further improving the comprehensive performance of cement-based materials when they are prepared.

Description

Technical Field

[0001] This invention belongs to the field of hydrated calcium silicate, and particularly relates to a hydrated calcium silicate based on the co-modification of linear silane and amino acids and its preparation method. Background Technology

[0002] Calcium silicate hydrate (CSH), as the most essential component of cement hydration products (accounting for about 60%-70%), is not only the main source of strength of cement-based materials, but also the key to determining the material's durability, pore structure and service life.

[0003] Currently, hydrated calcium silicate can be precisely synthesized in the laboratory using sol-gel, hydrothermal synthesis, and co-precipitation methods. This allows for precise control of the Ca / Si molar ratio, combined with high-speed shear stirring or specific dispersants, to prepare fine-particle, well-dispersed nanoscale CSH seeds. Based on these pre-prepared and artificially synthesized CSH nanoseeds, heterogeneous nucleation sites are provided for cement hydration. This not only shortens setting time but also alters the spatial distribution of hydration products, allowing them to fill the pores from the cement particle surface, thus optimizing the microstructure.

[0004] However, CSH produced solely through the natural hydration of cement often has structural defects. Through artificial modification, the material properties can be "customized." For example, existing technologies use linear silanes to modify hydrated calcium silicate, but it has been found that when applied to cement-based materials, the improvement in mechanical properties is limited.

[0005] Based on this, we are now studying a novel method for modifying calcium silicate hydrate to further improve the mechanical properties of cement-based materials prepared based on this modified calcium silicate hydrate. Summary of the Invention

[0006] Purpose of the invention: The technical problem to be solved by the present invention is to provide a novel modified calcium silicate hydrate to further improve the comprehensive performance of calcium silicate hydrate, thereby improving the comprehensive performance of cement materials prepared by its application.

[0007] Technical solution: The calcium silicate hydrate modified by linear silane and amino acid of the present invention is composed of the following raw materials by mass fraction: 99.81%-99.95% calcium silicate hydrate raw material and 0.05-0.19% linear silane, and 0.02-0.11% polar positively charged amino acid accounting for the total amount of calcium silicate hydrate raw material and linear silane.

[0008] Furthermore, the hydrated calcium silicate raw materials used in this modified hydrated calcium silicate include sodium silicate nonahydrate and anhydrous calcium chloride with a Ca / Si molar ratio of 0.8-1.5.

[0009] Furthermore, the linear silane used in this modified calcium silicate hydrate is selected from epoxy silanes, amino silanes, or alkyl silanes. Preferably, the linear silane is selected from γ-glycidyl etheroxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

[0010] Furthermore, the polar, positively charged amino acids used in this modified calcium silicate hydrate are selected from arginine, histidine, or lysine.

[0011] The method for preparing the above-mentioned calcium silicate hydrate based on the co-modification of linear silane and amino acids according to the present invention includes the following steps:

[0012] (1) Dissolve the positively charged amino acid in deionized water, adjust the pH to 4.5-5.5 with glacial acetic acid, add linear silane and ethanol, and stir at 35-40℃ for 30-60 min to obtain mixed solution A;

[0013] (2) Prepare anhydrous calcium chloride solution by adding mixed solution A to obtain mixed solution B;

[0014] (3) Prepare a sodium silicate nonahydrate solution containing sodium hydroxide, add mixed solution B dropwise to the sodium silicate nonahydrate solution containing sodium hydroxide, react at 50-60℃ for 12-24h, and obtain modified calcium silicate hydrate after washing and drying.

[0015] Furthermore, in this preparation method, the volume ratio of linear silane, ethanol and deionized water is 1:(3-5):(5-10).

[0016] Furthermore, in this preparation method, the concentration of the anhydrous calcium chloride solution is 0.1 mol / L-0.5 mol / L, and the concentration of the sodium silicate nonahydrate solution is 0.1 mol / L-0.5 mol / L.

[0017] Furthermore, in this preparation method, sodium hydroxide is added to adjust the pH of the reaction system in step (3) to 11.5-12.5.

[0018] Furthermore, in this preparation method, the concentration of sodium hydroxide is 1.0 mol / L-2.0 mol / L.

[0019] Beneficial effects: Compared with the prior art, the significant advantage of this invention is that the modified calcium silicate hydrate uses amino acids and linear silanes to co-modify the calcium silicate hydrate. Based on the synergistic effect of the two, it can promote the formation of an ordered stacked thin film of calcium silicate hydrate and tend to develop into an ordered parallel stacked layered structure. Therefore, when preparing cement-based materials based on it, it is possible to:

[0020] (1) It blocks the main channels for the transmission of corrosive media such as water, chloride ions, and sulfate ions, forming a physical barrier, which greatly reduces the permeability coefficient of cement-based materials and improves their service life;

[0021] (2) The dense film / lamellae structure formed has a large specific surface area and stronger interfacial bonding force. It is easy to grow epitaxially on the surface of aggregates to form a dense transition layer, which replaces the original loose and porous structure, thereby significantly improving the interfacial bonding strength of cement-based materials.

[0022] (3) It can improve the flexural strength and toughness of cement-based materials, so as to provide better deformation compatibility when subjected to external stress;

[0023] (4) After the formation of a dense film structure, the negative pressure effect generated by capillary tension will be weakened because the pore size is effectively refined to the nanoscale (even below the critical size of capillary action), thereby mechanistically alleviating the self-shrinkage and drying shrinkage cracks of hardened cement, i.e., the material. Attached Figure Description

[0024] Figure 1 SEM images of the modified hydrated calcium silicate prepared in the embodiments of the present invention; wherein, a corresponds to Examples 1-2, b corresponds to Examples 1-5, c corresponds to Examples 2-1, d corresponds to Examples 2-4, e corresponds to Examples 3-1, and f corresponds to Examples 3-4;

[0025] Figure 2 AFM diagrams of modified hydrated calcium silicate prepared according to the embodiments of the present invention are shown; where a corresponds to Examples 1-5, b corresponds to Examples 2-1, and c corresponds to Examples 3-4.

[0026] Figure 3 The Young's modulus distribution of the modified calcium silicate hydrate prepared in Examples 1-5 of this invention is shown in the diagram.

[0027] Figure 4 The probability distribution diagram of the elastic modulus of the modified calcium silicate hydrate prepared in Examples 1-5 of this invention;

[0028] Figure 5 The NMR spectra of the modified calcium silicate hydrate prepared in the embodiments of the present invention are shown below; where a corresponds to Examples 1-2, b corresponds to Examples 2-1, c corresponds to Examples 3-1, d corresponds to Examples 1-5, e corresponds to Examples 2-4, and f corresponds to Examples 3-4.

[0029] Figure 6 The XRD patterns are of the modified calcium silicate hydrate prepared in Examples 1-1 to 1-3 of this invention.

[0030] Figure 7The XRD patterns are of the modified calcium silicate hydrate prepared in Examples 1-4 to 1-6 of this invention.

[0031] Figure 8 The peak height and full width at half maximum (FWHM) of the modified calcium silicate prepared in Examples 1-1 to 1-3 of this invention are shown in the diagram.

[0032] Figure 9 The peak height and full width at half maximum (FWHM) of the modified calcium silicate prepared in Examples 1-4 to 1-6 of this invention are shown in the diagram.

[0033] Figure 10 The XRD patterns are of the modified hydrated calcium silicate prepared in Examples 2-1 to 2-3 of this invention.

[0034] Figure 11 The XRD patterns are of the modified calcium silicate hydrate prepared in Examples 2-4 to 2-6 of this invention.

[0035] Figure 12 The peak height and full width at half maximum (FWHM) of the modified calcium silicate prepared in Examples 2-1 to 2-3 of this invention are shown in the diagram.

[0036] Figure 13 The peak height and full width at half maximum (FWHM) of the modified calcium silicate prepared in Examples 2-4 to 2-6 of this invention are shown in the diagram.

[0037] Figure 14 The XRD patterns are of the modified hydrated calcium silicate prepared in Examples 3-1 to 3-3 of this invention.

[0038] Figure 15 The XRD patterns are of the modified calcium silicate hydrate prepared in Examples 3-4 to 3-6 of this invention.

[0039] Figure 16 The peak height and full width at half maximum (FWHM) of the modified calcium silicate prepared in Examples 3-1 to 3-3 of this invention are shown in the diagram.

[0040] Figure 17 The peak height and full width at half maximum (FWHM) of the modified calcium silicate prepared in Examples 3-4 to 3-6 of this invention are shown in the diagram.

[0041] Figure 18 The TG chromatograms are of the modified calcium silicate hydrate prepared in Examples 1-2, 1-5, 2-1, 2-4, 3-1, and 3-4 of this invention.

[0042] Figure 19 The DTG diagrams are of the modified calcium silicate hydrate prepared in Examples 1-2, 1-5, 2-1, 2-4, 3-1, and 3-4 of this invention.

[0043] Figure 20 Fourier transform infrared spectra of the modified hydrated calcium silicate prepared in the embodiments of the present invention; wherein, a corresponds to Examples 1-1 to 1-6; b corresponds to Examples 2-1 to 2-6; c corresponds to Examples 3-1 to 3-6;

[0044] Figure 21 900-1300 cm⁻¹ of CSH was modified with arginine and 3-APTES. -1 The results of the mathematical solution for the broad peak within the range are shown in the figure; where a is unmodified pure hydrated calcium silicate, b corresponds to modification using only APTES linear silanes from Examples 1-1 to 1-3, c corresponds to modification using only APTES linear silanes from Examples 1-4 to 1-6, d corresponds to Example 1-1, e corresponds to Example 1-2, f corresponds to Example 1-3, g corresponds to Example 1-4, h corresponds to Example 1-5, and i corresponds to Example 1-6;

[0045] Figure 22 900-1300 cm⁻¹ of CSH was modified with lysine and 3-APTES. -1 The results of the mathematical solution for the broad peak within the range are shown in the figure; where a is unmodified pure hydrated calcium silicate, b corresponds to modification using only APTES linear silanes from Examples 2-1 to 2-3, c corresponds to modification using only APTES linear silanes from Examples 2-4 to 2-6, d corresponds to Example 2-1, e corresponds to Example 2-2, f corresponds to Example 2-3, g corresponds to Example 2-4, h corresponds to Example 2-5, and i corresponds to Example 2-6;

[0046] Figure 23 CSH with histidine and 3-APTES co-modification at 900-1300 cm⁻¹ -1 The results of the mathematical solution for the broad peak within the range are shown in the figure; where a is unmodified pure hydrated calcium silicate, b corresponds to modification using only APTES linear silanes from Examples 3-1 to 3-3, c corresponds to modification using only APTES linear silanes from Examples 3-4 to 3-6, d corresponds to Example 3-1, e corresponds to Example 3-2, f corresponds to Example 3-3, g corresponds to Example 3-4, h corresponds to Example 3-5, and i corresponds to Example 3-6;

[0047] Figure 24 BET diagrams of the modified hydrated calcium silicate prepared in the embodiments of the present invention; wherein, a corresponds to Examples 1-5, b corresponds to Examples 2-1, and c corresponds to Examples 3-4;

[0048] Figure 25 The modified hydrated calcium silicate prepared for the embodiments of the present invention is in Figure 24 The proportion of various types of pores in the BET test. Detailed Implementation

[0049] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0050] In the following embodiments of the present invention, the calcium-silicon ratio of anhydrous calcium chloride to sodium silicate nonahydrate is 0.83.

[0051] Example 1-1 (CSH-55 0.1% Arg 0.05%)

[0052] The raw material composition of the modified hydrated calcium silicate in Example 1-1 is shown in Table 1 below.

[0053] Table 1 Raw material composition of Example 1-1

[0054]

[0055] The modified hydrated calcium silicate of Example 1-1 was prepared by the following steps:

[0056] (1) Dissolve arginine in deionized water, adjust the pH value to about pH 5 with glacial acetic acid, add 3-aminopropyltriethoxysilane (APTES linear silane) and ethanol, stir at 40℃ for 50 min to obtain mixed solution A; wherein the volume ratio of linear silane, ethanol and deionized water is 1:4:8.

[0057] (2) Prepare an anhydrous calcium chloride solution with a concentration of 0.3 mol / L, add mixed solution A to obtain mixed solution B;

[0058] (3) Prepare a sodium silicate nonahydrate solution containing sodium hydroxide. Add mixed solution B dropwise to the sodium silicate nonahydrate solution containing sodium hydroxide and react at 50°C for 24 hours. After washing and drying, modified calcium silicate hydrate is obtained. The concentration of sodium silicate nonahydrate solution is 0.3 mol / L. Sodium hydroxide is added to adjust the pH value of the reaction system in step (3) to about 12. The concentration of sodium hydroxide is 1.0 mol / L.

[0059] Examples 1-2 (CSH-55 0.1% Arg 0.1%)

[0060] The raw material composition of the modified hydrated calcium silicate in Examples 1-2 is shown in Table 2 below.

[0061] Table 2 Raw material components of Examples 1-2

[0062]

[0063] The preparation steps of the modified hydrated calcium silicate in Examples 1-2 are the same as those in Example 1-1.

[0064] Examples 1-3 (CSH-55 0.1% Arg 0.3%)

[0065] The raw material composition of the modified hydrated calcium silicate in Examples 1-3 is shown in Table 3 below.

[0066] Table 3 Raw material components of Examples 1-3

[0067]

[0068] The steps for modifying calcium silicate hydrate in Examples 1-3 are the same as those in Example 1.

[0069] Examples 1-4 (CSH-55 0.3% Arg 0.05%)

[0070] The raw material composition of the modified hydrated calcium silicate in Examples 1-4 is shown in Table 4 below.

[0071] Table 4 Raw material composition of Examples 1-4

[0072]

[0073] The steps for modifying calcium silicate hydrate in Examples 1-4 are the same as those in Example 1.

[0074] Examples 1-5 (CSH-55 0.3% Arg 0.1%)

[0075] The raw material composition of the modified hydrated calcium silicate in Examples 1-5 is shown in Table 5 below.

[0076] Table 5 Raw material components of Examples 1-5

[0077]

[0078] The steps for modifying calcium silicate hydrate in Examples 1-5 are the same as those in Example 1.

[0079] Examples 1-6 (CSH-55 0.3% Arg 0.3%)

[0080] The raw material composition of the modified hydrated calcium silicate in Examples 1-6 is shown in Table 6 below.

[0081] Table 6 Raw material components of Examples 1-6

[0082]

[0083] The steps for modifying calcium silicate hydrate in Examples 1-5 are the same as those in Example 1.

[0084] Example 2-1 (CSH-55 0.1% Lys 0.05%)

[0085] The raw material composition of the modified hydrated calcium silicate in Example 2-1 is shown in Table 7 below.

[0086] Table 7 Raw material composition of Example 2-1

[0087]

[0088] The steps for modifying calcium silicate hydrate in Example 2-1 are basically the same as those in Example 1.

[0089] Example 2-2 (CSH-55 0.1% Lys 0.1%)

[0090] The raw material composition of the modified hydrated calcium silicate in Example 2-2 is shown in Table 8 below.

[0091] Table 8 Raw material composition of Example 2-2

[0092]

[0093] The steps for modifying calcium silicate hydrate in Example 2-2 are the same as those in Example 1.

[0094] Examples 2-3 (CSH-55 0.1% Lys 0.3%)

[0095] The raw material composition of the modified hydrated calcium silicate in Examples 2-3 is shown in Table 9 below.

[0096] Table 9 Raw material components of Examples 2-3

[0097]

[0098] The steps for modifying calcium silicate hydrate in Examples 2-3 are basically the same as those in Example 1.

[0099] Examples 2-4 (CSH-55 0.3% Lys 0.05%)

[0100] The raw material composition of the modified hydrated calcium silicate in Examples 2-4 is shown in Table 10 below.

[0101] Table 10 Raw material composition of Examples 2-4

[0102]

[0103] The steps for modifying calcium silicate hydrate in Examples 2-4 are the same as those in Example 1.

[0104] Examples 2-5 (CSH-55 0.3% Lys 0.1%)

[0105] The raw material composition of the modified hydrated calcium silicate in Examples 2-5 is shown in Table 11 below.

[0106] Table 11 Raw material components of Examples 2-5

[0107]

[0108] The steps for modifying calcium silicate hydrate in Examples 2-5 are the same as those in Example 1.

[0109] Examples 2-6 (CSH-55 0.3% Lys 0.3%)

[0110] The raw material composition of the modified hydrated calcium silicate in Examples 2-6 is shown in Table 12 below.

[0111] Table 12 Raw material components of Examples 2-6

[0112]

[0113] The steps for modifying calcium silicate hydrate in Examples 2-6 are the same as those in Example 1.

[0114] Example 3-1 (CSH-55 0.1% His 0.05%)

[0115] The raw material composition of the modified hydrated calcium silicate in Example 3-1 is shown in Table 13 below.

[0116] Table 13 Raw material composition of Example 3-1

[0117]

[0118] The steps for modifying calcium silicate hydrate in Example 3-1 are basically the same as those in Example 1.

[0119] Example 3-2 (CSH-55 0.1% His 0.1%)

[0120] The raw material composition of the modified hydrated calcium silicate in Example 3-2 is shown in Table 14 below.

[0121] Table 14 Raw material composition of Example 3-2

[0122]

[0123] The steps for modifying calcium silicate hydrate in Example 3-2 are basically the same as those in Example 1.

[0124] Example 3-3 (CSH-55 0.1% His 0.3%)

[0125] The raw material composition of the modified hydrated calcium silicate in Example 3-3 is shown in Table 15 below.

[0126] Table 15 Raw material composition of Examples 3-3

[0127]

[0128] The steps for modifying calcium silicate hydrate in Examples 3-3 are the same as those in Example 1.

[0129] Examples 3-4 (CSH-55 0.3% His 0.05%)

[0130] The raw material composition of the modified hydrated calcium silicate in Examples 3-4 is shown in Table 16 below.

[0131] Table 16 Raw material components of Examples 3-4

[0132]

[0133] The steps for modifying calcium silicate hydrate in Examples 3-4 are the same as those in Example 1.

[0134] Examples 3-5 (CSH-55 0.3% His 0.1%)

[0135] The raw material composition of the modified hydrated calcium silicate in Examples 3-5 is shown in Table 17 below.

[0136] Table 17 Raw material components of Examples 3-5

[0137]

[0138] The steps for modifying calcium silicate hydrate in Examples 3-5 are basically the same as those in Example 1.

[0139] Examples 3-6 (CSH-55 0.3% His 0.3%)

[0140] The raw material composition of the modified hydrated calcium silicate in Examples 3-6 is shown in Table 18 below.

[0141] Table 18 Raw material components of Examples 3-6

[0142]

[0143] The steps for modifying calcium silicate hydrate in Examples 3-6 are basically the same as those in Example 1.

[0144] Structural and performance characterization

[0145] 1. SEM image

[0146] The hydrated calcium silicate samples prepared in Examples 1-2, 1-5, 2-1, 2-4, 3-1, and 3-4 were characterized by scanning electron microscopy, and the results are as follows: Figure 1 As shown. (Through) Figure 1 It can be seen that, Figure 1 (a) and Figure 1 (b) shows the arginine-modified CSH group sample, where the arginine group exhibits a film-like morphology with particle accumulation. In contrast, the lysine group shows primarily particle accumulation, as shown in [image / description]. Figure 1 (c) and (d) show a tendency towards a layered structure. Within the histidine sequence, the microstructure is predominantly thin-film-like, as shown in... Figure 1 (e) and Figure 1 (f). The reason for this is that linear silanes and positively charged amino acids of different polarities chemically combine with the CSH surface, improving the aggregation environment between particles and promoting the formation of a thin film-like microstructure through self-assembly.

[0147] 2. AFM diagram

[0148] Based on electron microscopy images, further nanoscale micromorphology analysis was performed on Examples 1-5, Examples 2-1, and Examples 3-4, and the results are as follows. Figure 2 As shown. On the surface of the formed thin film of hydrated calcium silicate, CSH-55 0.3% Arg 0.1% sample Figure 2 (a) Composed of spherical particles with a diameter between 300 and 800 nm; in contrast, Figure 2 (b) The CSH-550.1% Lys 0.05% sample is shown to consist of nanoparticles with diameters ranging from 200 to 600 nm. Figure 2 (c) The CSH-550.3% His 0.05% sample also exhibits spherical particle characteristics, with a particle size distribution between 200 and 500 nm. Further testing of the Young's modulus was conducted on a relatively smooth surface, and the results are as follows... Figure 3 and Figure 4 As shown.

[0149] 3. Elastic modulus analysis

[0150] Figure 3 The elastic modulus distribution of the CSH-55 0.3% Arg 0.1% modified CSH samples is shown, with an average value of 20.8 GPa. Further semi-quantitative mathematical solutions were performed on the mechanical curves of its Young's modulus, and the results are as follows: Figure 4As shown in Table 19, the CSH sample modified with CSH-55 0.3% Arg 0.1% had relative contents of VLD, LD, HD and UHD phases of 29.6%, 38.9%, 15.8% and 15.8%, respectively. In this experiment, the penetration depth of the AFM probe in the z-axis direction was only a few hundred picometers. Therefore, the measured elastic modulus reflects the mechanical properties of the basic building blocks of CSH.

[0151] Table 19 Probability density distribution of Young's modulus

[0152]

[0153] 4. Nuclear magnetic resonance analysis

[0154] Figure 5 This table presents solid-state NMR data of CSH samples co-modified with polar positively charged amino acids and linear silanes. Semi-quantitative mathematical solutions were used to calculate the proportions of Q0, Q1, and Q2 structures using software, and the results are summarized in Table 19. As shown in Table 20, the arginine group showed the most significant Q2-promoting effect in the CSH-55 0.1% Arg 0.1% sample, reaching a proportion of 50.1%. The Q2 structure content was also positively correlated with the degree of polymerization and average chain length, thus increasing the average chain length and degree of polymerization by 32% and 12% respectively compared to the blank sample. In the lysine group, lysine incorporation promoted the formation of Q2 structures while maintaining a relatively constant proportion of Q1 structures. In the histidine group, the CSH-55 0.1% His 0.05% sample showed that this incorporation promoted the formation of Q1 structures, reaching a proportion of 72%, resulting in a decrease in the degree of polymerization and average chain length. Most amino acid incorporations further increased the degree of aggregation. In this process, water molecules react with interlayer calcium ions to form ionic bonds, thereby promoting the construction of cross-linked silicate networks. Further mechanistic analysis reveals that the Si-O-Si chains, facilitated by 3-APTES molecules, ensure a certain degree of polymerization and chain length. Secondly, the insertion of positively charged polar amino acid molecules into the interlayer shields against the polarization effect of calcium ions, ensuring the orderliness of the CSH structure. Finally, the enrichment of the hydrogen bond network also provides a synergistic effect for improving the degree of polymerization and chain length.

[0155] Table 20 Qⁿ ratio of modified CSH samples

[0156]

[0157] 5. XRD pattern

[0158] XRD pattern correlation analysis of the modified hydrated calcium silicate prepared in the embodiments of the present invention is as follows: Figures 6 to 11 As shown.

[0159] Depend on Figure 6 and Figure 7 It was found that the incorporation of arginine did not significantly change the XRD peaks of CSH. Further analysis of the (002) interlayer spacing revealed that the incorporation of arginine increased the interlayer spacing, especially in the 3-APTES 0.3% Arg 0.1% sample, where the interlayer spacing reached the largest within the group, at 1.373. Quantitative analysis of the half-maximum width and peak height of the peaks around 30° was performed, and the results were statistically analyzed. Figure 8 and Figure 9 In the group with 0.1% 3-APTES doping, the peak height of the sample after incorporating arginine was higher than that of the pure 3-APTES system. However, in the group with 0.3% 3-APTES doping, the peak height after incorporating arginine was lower than that of the pure 3-APTES system. From the change in half-peak width (HWHM), the incorporation of arginine resulted in a certain increase in HWHM.

[0160] Depend on Figure 10 and Figure 11 It can be seen that the incorporation of Lys did not significantly change the XRD peaks of CSH. Figure 12 The interlayer spacing of (002) was analyzed. In the sample group with 0.1% 3-APTES doping, it is noteworthy that a Lys doping content of 0.05% had a significant impact on the interlayer spacing. However, in the sample group with 0.3% 3-APTES doping, the interlayer spacing was directly proportional to the Lys doping content. Quantitative analysis of the half-width at half-maximum (WHM) and peak height of the peak around 30° was performed, and the results were statistically analyzed. Figure 12 and Figure 13 .Depend on Figure 12 It can be seen that the peak height is increased by the incorporation of Lys compared to the pure 3-APTES system. From Figure 13 It can be seen that the peak height is reduced by incorporating Lys compared to the pure 3-APTES system. However, the change in the full width at half maximum (FWHM) shows that the incorporation of Lys leads to a certain increase in the FWHM.

[0161] Depend on Figure 14 and Figure 15 It can be seen that the incorporation of histidine did not significantly change the XRD peak of CSH. Figure 16 The interlayer spacing of (002) was analyzed. In the sample group with 0.1% 3-APTES doping, the incorporation of histidine increased the interlayer spacing, while in the sample group with 0.3% 3-APTES doping, the interlayer spacing was inversely proportional to the histidine doping. Quantitative analysis of the half-peak width and peak height of the peak around 30° was performed, and the results were statistically analyzed. Figure 16 and Figure 17 In the 0.1% 3-APTES group, the incorporation of histidine was directly proportional to the peak height, while in the 0.3% 3-APTES group, the incorporation of histidine decreased the peak height. Looking at the changes in the full width at half maximum (FWHM), the incorporation of histidine resulted in a certain increase in the FWHM.

[0162] 6. FTIR analysis

[0163] The Fourier transform infrared light of the modified hydrated calcium silicate prepared in the embodiments of the present invention is as follows: Figure 20 As shown in the figure, vibrational absorption peaks are present at 665 cm⁻¹, 967 cm⁻¹, 1641 cm⁻¹, 3448 cm⁻¹, 872 cm⁻¹, 1420 cm⁻¹, and 1491 cm⁻¹, with no significant chemical shift compared to the vibrational absorption peaks of pure CSH. Notably, when the 3-APTES doping content is 0.1% and the arginine doping content is 0.1%, and when the 3-APTES doping content is 0.3% and the arginine doping content is 0.3%, the intensity of the broad peak in the 900–1300 cm⁻¹ range is significantly enhanced. Since the peak intensity continuously increases with increasing silane doping, it indicates that the introduction of arginine may promote the formation of more Si–O bonds. The CSH structure is a complex composed of tobermorite-like structural units and geniet-like structural units. Specifically, in the 900–1300 cm⁻¹ range… -1 Within the broad peak range, 904-908 cm -1 and 1064-1076cm -1 The spectral pattern at this location belongs to a Jeanne-like structure, while the 962-970 cm⁻¹ structure... -1 and at approximately 1000 cm -1 The absorption band at that location corresponds to a Tobermullite-like structure.

[0164] Based on the above spectral assignments, for the 900-1300 cm⁻¹ -1 Mathematical calculations are performed on the broad peaks within the range, such as... Figures 21 to 23 As shown in the figure, and as shown in Tables 21 to 23, the results are as follows: the incorporation of arginine resulted in a 962-970 cm⁻¹ -1 The increased proportion of broad peaks in the tobermorite-like structures on the left and right sides affected the T / J ratio, resulting in a greater presence of tobermorite-like structures in the CSH structure. The incorporation of lysine improved the 962-970 cm⁻¹... -1 The proportion of broad peaks in the tobermorite-like structures on the left and right sides increased, reaching a maximum of 44.2%, resulting in a greater presence of tobermorite-like structures in the CSH structure. Similarly, the incorporation of histidine improved the 962-970 cm⁻¹... -1 The proportion of broad peaks in the Tobermullite-like structure on the left and right sides increased, reaching a maximum of 40.4%.

[0165] Table 21 Results of Fourier transform infrared spectrum broad peaks of the modified samples

[0166]

[0167] Table 22 Results of Fourier transform infrared spectrum broad peaks of the modified samples

[0168]

[0169] Table 23 Results of Fourier transform infrared spectrum broad peaks of the modified samples

[0170]

[0171] 7. Thermal Analysis

[0172] Thermal analysis was performed on the modified hydrated calcium silicate prepared in the embodiments of the present invention, and the results are as follows: Figure 18 and Figure 19 As shown, in the three sample groups (CSH-55 0.3% Arg 0.1%, CSH-55 0.3% His 0.05%, and CSH-55 0.1% His 0.05%), amino acids competed with calcium ions for sites, and some calcium ions were forced to coordinate with hydroxide ions to form calcium hydroxide, resulting in a significant weight change at around 400 °C. The amount of calcium hydroxide formed was low, and FTIR testing showed no new types of chemical bonds formed. Therefore, hydrogen bonding is the main driving force for changing the stacking structure when 3-APTES-modified CSH nanosheets are stacked. Figure 19 This is the DTG curve of the modified sample. The decomposition of the CSH-550.3% Arg 0.1% sample shows a more significant shift towards higher temperatures compared to other samples, indicating that the thermal stability of the modified sample is improved compared to the CSH blank group.

[0173] 8. BET Analysis

[0174] Figure 24 The BET results of silane-modified CSH experiments are presented. Nitrogen adsorption analysis determined that the most probable pore sizes of the CSH samples co-modified with linear silane and positively charged polar amino acids were 2.32 nm for arginine, 1.88 nm for lysine, and 3.88 nm for histidine. Figure 24 (a) Figure 24 (b) and Figure 24 (c) It can be seen that the cumulative pore size of the modified CSH samples in Examples 1-5 is much larger than that of the modified CSH samples in Examples 2-1 and 3-4. The analysis suggests that the insertion of positively charged polar amino acid molecules and 3-APTES molecules expands the interlayer spacing, leading to an increase in capillary size and number. The proportion of pore size at each scale is further summarized and plotted. Figure 25 .

[0175] Figure 25The specific proportions of various pore sizes in the CSH samples co-modified with polar positively charged amino acids and linear silanes were summarized in the BET test results. It was found that the proportions of pores with diameters of 0.3-2 nm, 2-5 nm, and 5-50 nm were the lowest in the Lys group, at 7%, 4%, and 23%, respectively. The proportion of pores larger than 50 nm was the highest in the Lys group. In contrast, the proportion of pores larger than 50 nm in Examples 1-5 was the lowest. This indicates that the modified CSH samples in Examples 1-5 predominantly formed small pores smaller than 50 nm. In the histidine group, pore sizes were predominantly larger than 50 nm, indicating that the steric hindrance effect of lysine and histidine was more pronounced, preventing the close packing of CSH particles and thus increasing the proportion of pores larger than 50 nm.

[0176] In summary, the above analysis shows that the co-modification of CSH samples with positively charged polar amino acids and 3-APTES has a significant impact on chemical bonds, porosity, and mechanical properties. Positively charged polar amino acid molecules and 3-APTES molecules intercalate between silicon chains, disrupting the order of the silicon chains and thus increasing the full width at half maximum (FWHM). However, this disruption of silicon chain order also provides sufficient space for the growth of tobermorite-like structures. The positively charged polar amino acids compete with calcium ions for sites, forming low calcium-to-silicon ratio regions locally, which promotes the formation of tobermorite-like structures. However, the following are exceptions: CSH-55 0.3% Arg 0.3%, CSH-55 0.1% Lys 0.05%, CSH-55 0.3% Lys 0.05%, and CSH-55 0.1% His 0.05%, where the T / J ratio decreases compared to the blank sample. The intercalation structure of organic compounds increases both the interlayer spacing and pore size, resulting in a larger cumulative pore volume compared to the blank sample. Similarly, the adsorption of free water also increases. Furthermore, in the CSH-55 0.3% Arg 0.05% and histidine samples, the positively charged polar amino acids compete with calcium ions for sites, forcing calcium ions to react with hydroxide ions to form calcium hydroxide. Simultaneously, the positively charged polar amino acids and 3-APTES promote the average chain length and degree of polymerization, having diverse effects on the microstructure. The CSH-55 0.3% Arg 0.1% and CSH-55 0.1% His 0.05% compositions show the best effects. This is likely due to the incorporation of positively charged polar amino acid molecules, resulting in directional and ordered adsorption, and the covalent interaction of the Si-O-Si bonds in the 3-APTES molecules, leading to the orderly stacking of CSH grains and the formation of a dense thin film. From the perspective of mechanical properties, the Young's modulus of the modified samples with arginine and 3-APTES was improved compared with that of the blank group, thus giving the CSH particles better mechanical properties.

Claims

1. A hydrated calcium silicate based on the co-modification of linear silanes and amino acids, characterized in that, By mass fraction, the modified calcium silicate hydrate is composed of the following raw materials: 99.81%-99.95% calcium silicate hydrate raw material and 0.05%-0.19% linear silane, and 0.02%-0.11% of polar positively charged amino acids, which together account for 0.02%-0.11% of the total amount of calcium silicate hydrate raw material and linear silane.

2. The calcium silicate hydrate modified by linear silane and amino acids according to claim 1, characterized in that, The hydrated calcium silicate raw material includes anhydrous calcium chloride and sodium silicate nonahydrate with a Ca / Si molar ratio of 0.8-1.

5.

3. The calcium silicate hydrate modified by linear silane and amino acids according to claim 1, characterized in that, The linear silane is selected from epoxy silanes, amino silanes, or alkyl silanes.

4. The calcium silicate hydrate modified by linear silane and amino acids according to claim 3, characterized in that, The linear silane is selected from γ-glycidyl etheroxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane.

5. The calcium silicate hydrate modified by linear silane and amino acids according to claim 1, characterized in that, The positively charged polar amino acid is selected from arginine, histidine, or lysine.

6. A method for preparing calcium silicate hydrate modified by linear silane and amino acids as described in claim 1, characterized in that, Includes the following steps: (1) Dissolve the positively charged amino acid in deionized water, adjust the pH to 4.5-5.5 with glacial acetic acid, add linear silane and ethanol, and stir at 35-40℃ for 30-60 min to obtain mixed solution A; (2) Prepare anhydrous calcium chloride solution by adding mixed solution A to obtain mixed solution B; (3) Prepare a sodium silicate nonahydrate solution containing sodium hydroxide, add mixed solution B dropwise to the sodium silicate nonahydrate solution containing sodium hydroxide, react at 50-60℃ for 12-24h, and obtain modified calcium silicate hydrate after washing and drying.

7. The method for preparing calcium silicate hydrate based on the co-modification of linear silanes and amino acids according to claim 6, characterized in that: The volume ratio of the linear silane, ethanol and deionized water is 1:(3-5):(5-10).

8. The method for preparing calcium silicate hydrate based on linear silane and amino acid co-modification according to claim 6, characterized in that: The concentration of the anhydrous calcium chloride solution is 0.1 mol / L-0.5 mol / L, and the concentration of the sodium silicate nonahydrate solution is 0.1 mol / L-0.5 mol / L.

9. The method for preparing calcium silicate hydrate based on the co-modification of linear silanes and amino acids according to claim 6, characterized in that: The sodium hydroxide is added to adjust the pH of the reaction system in step (3) to 11.5-12.

5.

10. The method for preparing calcium silicate hydrate based on linear silane and amino acid co-modification according to claim 9, characterized in that: The concentration of sodium hydroxide is 1.0 mol / L to 2.0 mol / L.

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