Calcium silicate hydrate modified hollow glass bead concrete and preparation method thereof

Abstract

The invention provides calcium silicate hydrate modified hollow glass bead concrete and a preparation method thereof.The preparation method comprises the steps that calcium silicate sol reacts with hollow glass beads, the surfaces of the hollow glass beads are wrapped with gel, and the calcium silicate hydrate modified hollow glass beads are obtained after calcination; and mixing the calcium silicate hydrate modified hollow glass beads, cement and wood fibers to obtain the calcium silicate hydrate modified hollow glass bead concrete. According to the preparation method, the problem that an interface weak area exists between the hollow glass beads and cement concrete is solved, and the problem that low-density beads float upwards and are layered in a concrete-based building material is solved.

Description

Technical Field

[0001] This invention relates to the field of hollow glass microspheres, and more specifically, to a hydrated calcium silicate modified hollow glass microsphere concrete and its preparation method. Background Technology

[0002] Hollow glass microspheres, as micron-sized, hollow glass spheres, are mainly composed of borosilicates. They possess advantages such as low density, high compressive strength, low thermal conductivity, and good flowability, and are widely used in engineering plastics, rubber, coatings, and buoyancy materials. In products containing hollow glass microspheres, the microsphere-matrix interface is a microscopically weak area that directly affects the macroscopic mechanical properties of the product. Existing technologies have conducted extensive research on surface modification of microspheres, mainly including coupling agent treatment, acid and alkali etching, plasma surface treatment, surface coating treatment, and surface graft polymerization modification. However, when microspheres modified by the above methods are used in concrete-based building materials, the introduction of new interfaces increases the water demand of the material system, exceeding the water required for concrete hydration. During the later stages of concrete hydration, excess water accumulates at the microsphere-matrix interface, resulting in a high water-cement ratio at the interface. The hydrated calcium hydroxide products accumulate and oriented at the interface, becoming a weak area that ultimately affects the macroscopic mechanical properties of the hardened material.

[0003] Patent application CN119613030A discloses a method for preparing high-strength lightweight concrete containing hollow glass microspheres. The method includes: Step 1: Activating the hollow glass microspheres, dispersing them in an ethanol solution, adding γ-aminopropyltriethoxysilane, heating, stirring, mixing, filtering, washing, and drying to obtain aminated hollow glass microspheres. Step 2: Mixing carbon fibers and N,N-dimethylformamide evenly, adding 1,8-diisocyanate and dibutyltin dilaurate, heating, stirring, mixing, filtering, washing, and drying to obtain modified carbon fibers. Step 3: Mixing N,N-dimethylformamide, aminated hollow glass microspheres, and modified carbon fibers evenly, heating, filtering, washing, and drying to obtain carbon fiber-grafted hollow glass microspheres. Step 4: Activate the rubber particles to obtain activated rubber particles. Disperse the activated rubber particles in an ethanol solution, add γ-glycidyl etheroxypropyltrimethoxysilane, stir and mix, filter, wash, and dry to obtain epoxy-modified rubber particles. Step 5: Mix acetone, epoxy-modified rubber particles, and itaconic acid evenly, filter, wash, and dry to obtain alkenyl-modified rubber particles. Step 6: Ultrasonically disperse the alkenyl-modified rubber particles in an ethanol solution, add polypropylene fiber, acrylic acid, and an initiator, filter, wash, and dry to obtain polypropylene fiber-grafted rubber particles. Step 7: Mix concrete, fly ash, carbon fiber-grafted hollow glass microspheres, lightweight sand, and deionized water, then add polypropylene fiber-grafted rubber particles and a water-reducing agent, stir, discharge, load into molds, vibrate to form, cover, and demold to obtain high-strength lightweight concrete containing hollow glass microspheres. This preparation method can solve the problem of poor strength of lightweight concrete. However, the main purpose of this preparation method is to modify hollow glass microspheres to avoid the aggregation of hollow glass microspheres. It cannot solve the problem of the weak interface zone between hollow glass microspheres and cement concrete. Summary of the Invention

[0004] To address the problem of weak interfacial zones between hollow glass microspheres and cement concrete, the technical solution adopted in this invention is: a method for preparing hydrated calcium silicate modified hollow glass microsphere concrete, comprising the following steps: Calcium silicate sol was reacted with hollow glass microspheres to coat the surface of the hollow glass microspheres with gel, and then calcined to obtain hydrated calcium silicate modified hollow glass microspheres. The hydrated calcium silicate modified hollow glass microspheres, cement, and wood fiber are mixed to obtain hydrated calcium silicate modified hollow glass microsphere concrete.

[0005] Based on the above, the mass ratio of the hydrated calcium silicate modified hollow glass microspheres, the cement, and the wood fiber is (15-25): (75-85): (0.3-0.8).

[0006] Based on the above, the ratio of hollow glass microspheres to calcium silicate sol is 5 g to 10 g of hollow glass microspheres per 100 mL of calcium silicate sol.

[0007] Based on the above, the calcium silicate sol is prepared from a calcium source compound and a silicon source compound, wherein the molar ratio of the calcium source compound to the silicon source compound is (0.5~1.5):1.

[0008] Based on the above, the calcium silicate sol is prepared by the following steps: The calcium source compound and the silicon source compound are mixed and dissolved, and then hydrochloric acid solution is added dropwise to adjust the pH of the solution to 5-6. The reaction is carried out under water bath conditions with stirring to obtain the calcium silicate sol.

[0009] Specifically, the calcium source compound is calcium nitrate; the silicon source compound is tetraethyl orthosilicate; ethanol is used as the solvent for dissolution, and hydrochloric acid is used to adjust the pH of the solution.

[0010] Based on the above, the hydrated calcium silicate modified hollow glass microspheres are prepared by the following steps: The hollow glass microspheres were added to the calcium silicate sol, stirred and dispersed, and then allowed to stand at room temperature for aging treatment to allow the colloidal particles in the sol to fully polymerize and form a gel, which coated the surface of the hollow glass microspheres. After filtration, washing, and drying, the temperature was increased from room temperature to 200℃~500℃ at a heating rate of 5℃ / min, and calcined at this temperature for 2h~4h. Then, the temperature was reduced to room temperature at a cooling rate of 5℃ / min to obtain the hydrated calcium silicate modified hollow glass microspheres.

[0011] Based on the above, before reacting the calcium silicate sol with the hollow glass microspheres, the hollow glass microspheres are further subjected to ultrasonic cleaning and drying.

[0012] The present invention also provides a hydrated calcium silicate modified hollow glass microsphere concrete, which is prepared by the above preparation method.

[0013] This invention has significant substantive features and remarkable progress compared to existing technologies. Specifically, the method for preparing hydrated calcium silicate modified hollow glass microsphere concrete provided by this invention has the following beneficial effects: (1) The interface compatibility problem has been solved.

[0014] Introducing hollow glass microspheres into wet-mix cement concrete increases the water demand of the material system due to the large number of new interfaces formed by the microspheres. This water demand exceeds the water required for concrete hydration. During the later stages of concrete hydration, excess water accumulates at the microsphere-matrix interface, resulting in a high water-cement ratio. The hydrated calcium hydroxide products also accumulate and oriented at the interface, creating a weak zone that ultimately affects the macroscopic mechanical properties of the hardened material. However, by modifying the hollow glass microspheres by depositing a nano-hydrated calcium silicate layer, the compatibility between the hydrated calcium silicate layer and the concrete hydration product gel is improved, thus optimizing the weak interfacial zone. Furthermore, the nano-hydrated calcium silicate layer can act as a seed for hydration products, inducing more hydration product gel to grow at the interface, thus densifying the interfacial transition zone and ultimately improving the macroscopic mechanical properties of the finished product.

[0015] (2) The problem of floating and stratification of low-density microspheres in concrete matrix building materials has been solved. The controllable deposition of nano-hydrated calcium silicate layer on the surface of microspheres can increase the density of microspheres and reduce the density difference between microspheres and concrete matrix, thus solving the problem of microsphere floating and stratification in the concrete product preparation process.

[0016] Meanwhile, this preparation method has advantages such as mild reaction conditions, the ability to achieve uniform doping at the molecular level, and the ability to precisely control the composition and structure of materials. Detailed Implementation

[0017] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0018] Example 1 This embodiment provides a method for preparing hydrated calcium silicate modified hollow glass microsphere concrete, including the following steps: Preparation of calcium silicate sol: Weigh 0.05 mol calcium nitrate and 0.1 mol tetraethyl orthosilicate, add them to 100 mL ethanol, and stir until completely dissolved to form a mixed solution. Add hydrochloric acid solution dropwise to the mixed solution to adjust the pH to 5. Place the solution in a water bath at 60 °C and stir for 2 h to obtain calcium silicate sol.

[0019] Hollow glass microspheres pretreatment: 5g of hollow glass microspheres were placed in deionized water and then placed in an ultrasonic cleaner. The microspheres were ultrasonically cleaned at a frequency of 40kHz for 30 minutes to remove surface impurities and oil. The cleaned hollow glass microspheres were then dried in an oven at 80℃ for 2 hours.

[0020] The hollow glass microspheres were modified by adding pretreated hollow glass microspheres to the calcium silicate sol and stirring at 250 rpm for 40 minutes to ensure uniform dispersion. The mixture was then allowed to stand at room temperature for 24 hours to allow the colloidal particles in the sol to fully polymerize and form a gel, which then coated the surface of the hollow glass microspheres. The modified hollow glass microspheres were separated by filtration and washed three times with deionized water, each wash lasting 5 minutes. The washed modified hollow glass microspheres were then dried in an oven at 80°C for 2 hours.

[0021] After calcination, the dried modified hollow glass microspheres are evenly spread in a ceramic crucible to prevent excessive accumulation that could affect the calcination effect. The ceramic crucible is then placed in a muffle furnace, and the temperature is increased from room temperature to 200°C at a rate of 5°C / min, and maintained at this temperature for 4 hours. After calcination, the muffle furnace temperature is reduced to room temperature at a rate of 5°C / min to obtain the finished product of hydrated calcium silicate modified hollow glass microspheres. The finished product of hydrated calcium silicate modified hollow glass microspheres, cement, and wood fibers are mixed to obtain hydrated calcium silicate modified hollow glass microsphere concrete.

[0022] In practical applications, concrete is prepared by using 20 parts of hydrated calcium silicate modified hollow glass microspheres, 80 parts of cement, and 0.4 parts of wood fiber.

[0023] Specifically, in this embodiment, the hollow glass microspheres used are HL20 hollow glass microspheres produced by Zhengzhou Shenglait Hollow Microsphere New Material Co., Ltd. The true density of these HL20 hollow glass microspheres is 0.18 g / cm³ to 0.22 g / cm³, the bulk density is 0.10 g / cm³ to 0.12 g / cm³, the compressive strength is 500 Psi, and the particle size distribution has a D50 of 65 μm and a D90 of 110 μm.

[0024] Specifically, the hydrated calcium silicate modified hollow glass microspheres prepared in Example 1 are hydrated calcium silicate modified hollow glass microspheres with low calcium-to-silicon molar ratio, low hydrolysis temperature, and high acid concentration.

[0025] This embodiment also provides a hydrated calcium silicate modified hollow glass microsphere concrete prepared by the above preparation method.

[0026] The bulk density of the modified hollow glass microspheres prepared in Example 1 was tested to be 0.126 g / cm³. 3 The compressive strength of the concrete after solidification is 7.81 MPa and the flexural strength is 0.62 MPa.

[0027] Example 2 This embodiment provides a method for preparing hydrated calcium silicate modified hollow glass microsphere concrete, including the following steps: Preparation of calcium silicate sol: Weigh 0.05 mol calcium nitrate and 0.1 mol tetraethyl orthosilicate, add them to 100 mL ethanol, and stir until completely dissolved to form a mixed solution. Add hydrochloric acid solution dropwise to the mixed solution to adjust the pH to 5.5. Place the solution in a water bath at 70 °C and stir for 2 h to obtain calcium silicate sol.

[0028] Hollow glass microsphere pretreatment: 5g of hollow glass microspheres were placed in deionized water and ultrasonically cleaned at a frequency of 40kHz for 30 minutes to remove surface impurities and oil. The cleaned hollow glass microspheres were then dried in an oven at 80℃ for 2 hours.

[0029] Hollow glass microsphere modification: Pretreated hollow glass microspheres were added to a calcium silicate sol and stirred at 250 rpm for 40 min to ensure uniform dispersion. The mixture was then allowed to stand at room temperature for 24 h to allow the colloidal particles in the sol to fully polymerize and form a gel, which then coated the surface of the hollow glass microspheres. The modified hollow glass microspheres were separated by filtration and washed three times with deionized water, each time for 5 min. The washed modified hollow glass microspheres were then dried in an oven at 80 °C for 2 h.

[0030] After calcination, the dried modified hollow glass microspheres were evenly spread in a ceramic crucible to prevent excessive accumulation of microspheres, which would affect the calcination effect. The ceramic crucible was then placed in a muffle furnace, and the temperature was increased from room temperature to 300°C at a rate of 5°C / min, and maintained at this temperature for 2 hours. After calcination, the temperature of the muffle furnace was reduced to room temperature at a rate of 5°C / min, finally yielding hydrated calcium silicate modified hollow glass microspheres with a low calcium-to-silicon molar ratio, medium hydrolysis temperature, and medium acid concentration.

[0031] The hydrated calcium silicate modified hollow glass microspheres, cement, and wood fiber are mixed to obtain hydrated calcium silicate modified hollow glass microsphere concrete. In specific applications, concrete is prepared with a ratio of 20 parts hydrated calcium silicate modified hollow glass microspheres, 80 parts cement, and 0.4 parts wood fiber.

[0032] Specifically, in this embodiment, the hollow glass microspheres used are HL20 hollow glass microspheres produced by Zhengzhou Shenglait Hollow Microsphere New Material Co., Ltd. The true density of these HL20 hollow glass microspheres is 0.18 g / cm³ to 0.22 g / cm³, the bulk density is 0.10 g / cm³ to 0.12 g / cm³, the compressive strength is 500 Psi, and the particle size distribution has a D50 of 65 μm and a D90 of 110 μm.

[0033] Specifically, the hydrated calcium silicate modified hollow glass microspheres prepared in Example 2 are hydrated calcium silicate modified hollow glass microspheres with low calcium-to-silicon molar ratio, medium hydrolysis temperature, and medium acid concentration.

[0034] This embodiment also provides a hydrated calcium silicate modified hollow glass microsphere concrete prepared by the above preparation method.

[0035] The bulk density of the modified hollow glass microspheres prepared in Example 2 was tested to be 0.138 g / cm³. 3 The compressive strength of the concrete after solidification is 9.33 MPa and the flexural strength is 0.83 MPa.

[0036] Example 3 This embodiment provides a method for preparing hydrated calcium silicate modified hollow glass microsphere concrete, including the following steps: Preparation of calcium silicate sol: Weigh 0.05 mol of calcium nitrate and 0.1 mol of tetraethyl orthosilicate, add them to 100 mL of ethanol, and stir until completely dissolved to form a mixed solution. Add hydrochloric acid solution dropwise to the mixed solution to adjust the pH to 6. Place the solution in a water bath at 80 °C and stir for 2 h to obtain calcium silicate sol. The hydrolysis reaction of tetraethyl orthosilicate and calcium nitrate is accelerated at high hydrolysis temperatures, but due to the low calcium-to-silicon molar ratio, the resulting sol network structure is relatively loose, and the particle size is relatively large.

[0037] Hollow glass microspheres pretreatment: 5g of hollow glass microspheres were placed in deionized water and ultrasonically cleaned at a frequency of 40kHz for 30 minutes to remove surface impurities and oil. The cleaned hollow glass microspheres were then placed in an 80℃ oven and dried for 2 hours until their quality no longer changed.

[0038] Hollow glass microsphere modification: Pretreated hollow glass microspheres were added to a calcium silicate sol and stirred at 250 rpm for 40 min to ensure uniform dispersion. The mixture was then allowed to stand at room temperature for 24 h to allow the colloidal particles in the sol to fully polymerize and form a gel, which then coated the surface of the hollow glass microspheres. The modified hollow glass microspheres were separated by filtration and washed three times with deionized water, each time for 5 min. The washed modified hollow glass microspheres were then dried in an oven at 80 °C for 2 h.

[0039] After calcination, the dried modified hollow glass microspheres were evenly spread in a clean ceramic crucible, avoiding excessive accumulation of microspheres which would affect the calcination effect. The ceramic crucible was then placed in a muffle furnace, and the temperature was increased from room temperature to 300°C at a rate of 5°C / min, and maintained at this temperature for 3 hours. After calcination, the muffle furnace temperature was reduced to room temperature at a rate of 5°C / min, finally yielding the finished product of hydrated calcium silicate modified hollow glass microspheres.

[0040] The hydrated calcium silicate modified hollow glass microspheres, cement, and wood fiber are mixed to obtain hydrated calcium silicate modified hollow glass microsphere concrete. In specific applications, concrete is prepared with a ratio of 20 parts hydrated calcium silicate modified hollow glass microspheres, 80 parts cement, and 0.4 parts wood fiber.

[0041] Specifically, in this embodiment, the hollow glass microspheres used are HL20 hollow glass microspheres produced by Zhengzhou Shenglait Hollow Microsphere New Material Co., Ltd. The true density of these HL20 hollow glass microspheres is 0.18 g / cm³ to 0.22 g / cm³, the bulk density is 0.10 g / cm³ to 0.12 g / cm³, the compressive strength is 500 Psi, and the particle size distribution has a D50 of 65 μm and a D90 of 110 μm.

[0042] Specifically, the hydrated calcium silicate modified hollow glass microspheres prepared in Example 3 are modified hollow glass microspheres with low calcium-to-silicon molar ratio, high hydrolysis temperature, and low acid concentration.

[0043] This embodiment also provides a hydrated calcium silicate modified hollow glass microsphere concrete prepared by the above preparation method. The bulk density of the modified hollow glass microspheres prepared in this embodiment 3 was tested to be 0.144 g / cm³. 3 The compressive strength of the concrete after solidification is 10.13 MPa and the flexural strength is 0.93 MPa.

[0044] Example 4 This embodiment provides a method for preparing hydrated calcium silicate modified hollow glass microsphere concrete, including the following steps: Preparation of calcium silicate sol: Weigh 0.1 mol calcium nitrate and 0.1 mol tetraethyl orthosilicate, add them to 100 mL ethanol, and stir until completely dissolved to form a mixed solution. Add hydrochloric acid solution dropwise to the mixed solution to adjust the pH to 5. Place the solution in a water bath at 60 °C and stir for 2 h. High acid concentration accelerates the reaction rate, but low hydrolysis temperature slows down the reaction rate, resulting in a relatively loose sol network.

[0045] Hollow glass microspheres pretreatment: 5g of hollow glass microspheres were placed in deionized water and ultrasonically cleaned at a frequency of 40kHz for 30 minutes to remove surface impurities and oil. The cleaned hollow glass microspheres were then placed in an 80℃ oven and dried for 2 hours until their quality no longer changed.

[0046] Hollow glass microsphere modification involved adding pretreated hollow glass microspheres to a calcium silicate sol and stirring at 250 rpm for 40 minutes to ensure uniform dispersion. The mixture was then allowed to stand at room temperature for 24 hours to allow the colloidal particles in the sol to fully polymerize and form a gel, coating the surface of the hollow glass microspheres. The modified hollow glass microspheres were separated by filtration and washed three times with deionized water, each wash lasting 5 minutes. The washed modified hollow glass microspheres were then dried in an oven at 80°C for 2 hours, resulting in a relatively uniform gel coating.

[0047] After calcination, the dried modified hollow glass microspheres were evenly spread in a clean ceramic crucible, avoiding excessive accumulation of microspheres which would affect the calcination effect. The ceramic crucible containing the microspheres was placed in a muffle furnace, and the temperature was increased from room temperature to 300℃ at a heating rate of 5℃ / min, and maintained at this temperature for calcination for 4 hours. After calcination, the temperature of the muffle furnace was reduced to room temperature at a cooling rate of 5℃ / min, finally obtaining the finished product of hydrated calcium silicate modified hollow glass microspheres.

[0048] The hydrated calcium silicate modified hollow glass microspheres, cement, and wood fiber are mixed to obtain hydrated calcium silicate modified hollow glass microsphere concrete. In specific applications, concrete is prepared with a ratio of 20 parts hydrated calcium silicate modified hollow glass microspheres, 80 parts cement, and 0.4 parts wood fiber.

[0049] Specifically, in this embodiment, the hollow glass microspheres used are HL20 hollow glass microspheres produced by Zhengzhou Shenglait Hollow Microsphere New Material Co., Ltd. The true density of these HL20 hollow glass microspheres is 0.18 g / cm³ to 0.22 g / cm³, the bulk density is 0.10 g / cm³ to 0.12 g / cm³, the compressive strength is 500 Psi, and the particle size distribution has a D50 of 65 μm and a D90 of 110 μm.

[0050] Specifically, the hydrated calcium silicate modified hollow glass microspheres prepared in Example 4 are hollow glass microspheres modified with a medium calcium-to-silicon molar ratio, low hydrolysis temperature, and high acid concentration.

[0051] This embodiment also provides a hydrated calcium silicate modified hollow glass microsphere concrete prepared by the above preparation method. The bulk density of the modified hollow glass microspheres prepared in Example 4 was tested to be 0.155 g / cm³. 3The compressive strength of the concrete after solidification is 11.0 MPa and the flexural strength is 1.16 MPa.

[0052] Example 5 This embodiment provides a method for preparing hydrated calcium silicate modified hollow glass microsphere concrete, including the following steps: Preparation of calcium silicate sol: Weigh 0.1 mol calcium nitrate and 0.1 mol tetraethyl orthosilicate, add them to 100 mL ethanol, and stir until completely dissolved to form a mixed solution. Add hydrochloric acid solution dropwise to the mixed solution to adjust the pH to 5.5. Place the solution in a water bath at 70 °C and stir for 2 h.

[0053] Hollow glass microsphere pretreatment: 5g of hollow glass microspheres were placed in deionized water and ultrasonically cleaned at a frequency of 40kHz for 30 minutes to remove surface impurities and oil. The cleaned hollow glass microspheres were then placed in an oven at 80℃ and dried for 2 hours until their mass no longer changed, yielding calcium silicate sol.

[0054] Hollow glass microsphere modification: Pretreated hollow glass microspheres were added to a calcium silicate sol and stirred at 250 rpm for 40 min to ensure uniform dispersion. The mixture was then allowed to stand at room temperature for 24 h to allow the colloidal particles in the sol to fully polymerize and form a gel, which then coated the surface of the hollow glass microspheres. The modified hollow glass microspheres were separated by filtration and washed three times with deionized water, each time for 5 min. The washed modified hollow glass microspheres were then dried in an oven at 80 °C for 2 h.

[0055] After calcination, the dried modified hollow glass microspheres were evenly spread in a clean ceramic crucible, avoiding excessive accumulation of microspheres which would affect the calcination effect. The ceramic crucible containing the microspheres was placed in a muffle furnace, and the temperature was increased from room temperature to 400℃ at a heating rate of 5℃ / min, and maintained at this temperature for 2 hours. After calcination, the temperature of the muffle furnace was reduced to room temperature at a cooling rate of 5℃ / min, finally obtaining the finished product of hydrated calcium silicate modified hollow glass microspheres.

[0056] The hydrated calcium silicate modified hollow glass microspheres, cement, and wood fiber are mixed to obtain hydrated calcium silicate modified hollow glass microsphere concrete. In specific applications, concrete is prepared with a ratio of 20 parts hydrated calcium silicate modified hollow glass microspheres, 80 parts cement, and 0.4 parts wood fiber.

[0057] Specifically, in this embodiment, the hollow glass microspheres used are HL20 hollow glass microspheres produced by Zhengzhou Shenglait Hollow Microsphere New Material Co., Ltd. The true density of these HL20 hollow glass microspheres is 0.18 g / cm³ to 0.22 g / cm³, the bulk density is 0.10 g / cm³ to 0.12 g / cm³, the compressive strength is 500 Psi, and the particle size distribution has a D50 of 65 μm and a D90 of 110 μm.

[0058] Specifically, the hydrated calcium silicate modified hollow glass microspheres prepared in Example 5 are hydrated calcium silicate modified hollow glass microspheres with medium calcium-silicon molar ratio, medium hydrolysis temperature, and medium acid concentration.

[0059] This embodiment also provides a hydrated calcium silicate modified hollow glass microsphere concrete prepared by the above preparation method. The bulk density of the modified hollow glass microspheres prepared in this embodiment 5 was tested to be 0.179 g / cm³. 3 The compressive strength of the concrete after solidification is 12.83 MPa and the flexural strength is 1.46 MPa.

[0060] Example 6 This embodiment provides a method for preparing hydrated calcium silicate modified hollow glass microsphere concrete, including the following steps: Preparation of calcium silicate sol: Weigh 0.1 mol of calcium nitrate and 0.1 mol of tetraethyl orthosilicate, add them to 100 mL of ethanol, and stir until completely dissolved to form a mixed solution. Add hydrochloric acid solution dropwise to the mixed solution to adjust the pH to 6. Place the solution in a water bath at 80 °C and stir for 2 h to obtain calcium silicate sol.

[0061] Hollow glass microspheres pretreatment: 5g of hollow glass microspheres were placed in deionized water and ultrasonically cleaned at a frequency of 40kHz for 30 minutes to remove surface impurities and oil. The cleaned hollow glass microspheres were then placed in an 80℃ oven and dried for 2 hours until their quality no longer changed.

[0062] Hollow glass microsphere modification: Pretreated hollow glass microspheres were added to a calcium silicate sol and stirred at 250 rpm for 40 min to ensure uniform dispersion. The mixture was then allowed to stand at room temperature for 24 h to allow the colloidal particles in the sol to fully polymerize and form a gel, which then coated the surface of the hollow glass microspheres. The modified hollow glass microspheres were separated by filtration and washed three times with deionized water, each time for 5 min. The washed modified hollow glass microspheres were then dried in an oven at 80 °C for 2 h.

[0063] After calcination, the dried modified hollow glass microspheres were evenly spread in a clean ceramic crucible, avoiding excessive accumulation of microspheres which would affect the calcination effect. The ceramic crucible containing the microspheres was placed in a muffle furnace, and the temperature was increased from room temperature to 400℃ at a heating rate of 5℃ / min, and maintained at this temperature for calcination for 4 hours. After calcination, the temperature of the muffle furnace was reduced to room temperature at a cooling rate of 5℃ / min, finally obtaining the finished product of hydrated calcium silicate modified hollow glass microspheres.

[0064] The hydrated calcium silicate modified hollow glass microspheres, cement, and wood fiber are mixed to obtain hydrated calcium silicate modified hollow glass microsphere concrete. In specific applications, concrete is prepared with a ratio of 20 parts hydrated calcium silicate modified hollow glass microspheres, 80 parts cement, and 0.4 parts wood fiber.

[0065] Specifically, in this embodiment, the hollow glass microspheres used are HL20 hollow glass microspheres produced by Zhengzhou Shenglait Hollow Microsphere New Material Co., Ltd. The true density of these HL20 hollow glass microspheres is 0.18 g / cm³ to 0.22 g / cm³, the bulk density is 0.10 g / cm³ to 0.12 g / cm³, the compressive strength is 500 Psi, and the particle size distribution has a D50 of 65 μm and a D90 of 110 μm.

[0066] Specifically, the hydrated calcium silicate modified hollow glass microspheres prepared in Example 6 are hydrated calcium silicate modified hollow glass microspheres with medium calcium-silicon molar ratio, high hydrolysis temperature, and low acid concentration.

[0067] This embodiment also provides a hydrated calcium silicate modified hollow glass microsphere concrete prepared by the above preparation method. The bulk density of the modified hollow glass microspheres prepared in Example 6 was tested to be 0.163 g / cm³. 3 The compressive strength of the concrete after solidification is 11.72 MPa and the flexural strength is 1.22 MPa.

[0068] Example 7 This embodiment provides a method for preparing hydrated calcium silicate modified hollow glass microsphere concrete, including the following steps: Preparation of calcium silicate sol: Weigh 0.15 mol calcium nitrate and 0.1 mol tetraethyl orthosilicate, add them to 100 mL ethanol, and stir until completely dissolved to form a mixed solution. Add hydrochloric acid solution dropwise to the mixed solution to adjust the pH to 5. Place the solution in a water bath at 60 °C and stir for 2 h to obtain calcium silicate sol.

[0069] Hollow glass microspheres pretreatment: 5g of hollow glass microspheres were placed in deionized water and ultrasonically cleaned at a frequency of 40kHz for 30 minutes to remove surface impurities and oil. The cleaned hollow glass microspheres were then placed in an 80℃ oven and dried for 2 hours until their quality no longer changed.

[0070] Hollow glass microspheres were modified by adding pretreated hollow glass microspheres to a calcium silicate sol and stirring at 250 rpm for 40 min to ensure uniform dispersion. The mixture was then allowed to stand at room temperature for 24 h to allow the colloidal particles in the sol to fully polymerize and form a gel, which then coated the surface of the hollow glass microspheres, resulting in a relatively uniform gel coating. The modified hollow glass microspheres were separated by filtration and washed three times with deionized water, each wash lasting 5 min. The washed modified hollow glass microspheres were then dried in an oven at 80 °C for 2 h.

[0071] After calcination, the dried modified hollow glass microspheres were evenly spread in a clean ceramic crucible, avoiding excessive accumulation of microspheres which would affect the calcination effect. The ceramic crucible containing the microspheres was placed in a muffle furnace, and the temperature was increased from room temperature to 400℃ at a heating rate of 5℃ / min, and maintained at this temperature for calcination for 3 hours. After calcination, the temperature of the muffle furnace was reduced to room temperature at a cooling rate of 5℃ / min, finally obtaining the finished product of hydrated calcium silicate modified hollow glass microspheres.

[0072] The hydrated calcium silicate modified hollow glass microspheres, cement, and wood fiber are mixed to obtain hydrated calcium silicate modified hollow glass microsphere concrete. In specific applications, concrete is prepared with a ratio of 20 parts hydrated calcium silicate modified hollow glass microspheres, 80 parts cement, and 0.4 parts wood fiber.

[0073] Specifically, in this embodiment, the hollow glass microspheres used are HL20 hollow glass microspheres produced by Zhengzhou Shenglait Hollow Microsphere New Material Co., Ltd. The true density of these HL20 hollow glass microspheres is 0.18 g / cm³ to 0.22 g / cm³, the bulk density is 0.10 g / cm³ to 0.12 g / cm³, the compressive strength is 500 Psi, and the particle size distribution has a D50 of 65 μm and a D90 of 110 μm.

[0074] Specifically, the hydrated calcium silicate modified hollow glass microspheres prepared in Example 7 are hydrated calcium silicate modified hollow glass microspheres with high calcium-to-silicon molar ratio, low hydrolysis temperature, and high acid concentration.

[0075] This embodiment also provides a hydrated calcium silicate modified hollow glass microsphere concrete prepared by the above preparation method. The bulk density of the modified hollow glass microspheres prepared in Example 7 was tested to be 0.152 g / cm³. 3The compressive strength of the concrete after solidification is 10.61 MPa and the flexural strength is 1.05 MPa.

[0076] Example 8 This embodiment provides a method for preparing hydrated calcium silicate modified hollow glass microsphere concrete, including the following steps: Preparation of calcium silicate sol: Weigh 0.15 mol calcium nitrate and 0.1 mol tetraethyl orthosilicate, add them to 100 mL ethanol, and stir until completely dissolved to form a mixed solution. Slowly add hydrochloric acid solution to the mixed solution to adjust the pH to 5.5. Place the solution in a water bath at 70 °C and stir for 2 h to obtain calcium silicate sol.

[0077] Hollow glass microspheres pretreatment: 5g of hollow glass microspheres were placed in deionized water and ultrasonically cleaned at a frequency of 40kHz for 30 minutes to remove surface impurities and oil. The cleaned hollow glass microspheres were then placed in an 80℃ oven and dried for 2 hours until their quality no longer changed.

[0078] Hollow glass microsphere modification: Pretreated hollow glass microspheres were added to a calcium silicate sol and stirred at 250 rpm for 40 min to ensure uniform dispersion. The mixture was then allowed to stand at room temperature for 24 h to allow the colloidal particles in the sol to fully polymerize and form a gel, which then coated the surface of the hollow glass microspheres. The modified hollow glass microspheres were separated by filtration and washed three times with deionized water, each time for 5 min. The washed modified hollow glass microspheres were then dried in an oven at 80 °C for 2 h.

[0079] After calcination, the dried modified hollow glass microspheres were evenly spread in a clean ceramic crucible, avoiding excessive accumulation of microspheres which would affect the calcination effect. The ceramic crucible containing the microspheres was placed in a muffle furnace, and the temperature was increased from room temperature to 500℃ at a heating rate of 5℃ / min, and maintained at this temperature for 2 hours. After calcination, the temperature of the muffle furnace was reduced to room temperature at a cooling rate of 5℃ / min, finally obtaining the finished product of hydrated calcium silicate modified hollow glass microspheres.

[0080] The hydrated calcium silicate modified hollow glass microspheres, cement, and wood fiber are mixed to obtain hydrated calcium silicate modified hollow glass microsphere concrete. In specific applications, concrete is prepared with a ratio of 20 parts hydrated calcium silicate modified hollow glass microspheres, 80 parts cement, and 0.4 parts wood fiber.

[0081] Specifically, in this embodiment, the hollow glass microspheres used are HL20 hollow glass microspheres produced by Zhengzhou Shenglait Hollow Microsphere New Material Co., Ltd. The true density of these HL20 hollow glass microspheres is 0.18 g / cm³ to 0.22 g / cm³, the bulk density is 0.10 g / cm³ to 0.12 g / cm³, the compressive strength is 500 Psi, and the particle size distribution has a D50 of 65 μm and a D90 of 110 μm.

[0082] Specifically, the hydrated calcium silicate modified hollow glass microspheres prepared in Example 8 are hydrated calcium silicate modified hollow glass microspheres with high calcium-to-silicon molar ratio, medium hydrolysis temperature, and medium acid concentration.

[0083] This embodiment also provides a hydrated calcium silicate modified hollow glass microsphere concrete prepared by the above preparation method. The bulk density of the modified hollow glass microspheres prepared in this embodiment 8 was tested to be 0.169 g / cm³. 3 The compressive strength of the concrete after solidification is 12.1 MPa and the flexural strength is 1.38 MPa.

[0084] Example 9 This embodiment provides a method for preparing hydrated calcium silicate modified hollow glass microsphere concrete, including the following steps: Preparation of calcium silicate sol: Weigh 0.15 mol of calcium nitrate and 0.1 mol of tetraethyl orthosilicate, add them to 100 mL of ethanol, and stir until completely dissolved to form a mixed solution. Add hydrochloric acid solution dropwise to the mixed solution to adjust the pH to 6. Place the solution in a water bath at 80 °C and stir for 2 h to obtain calcium silicate sol.

[0085] Hollow glass microspheres pretreatment: 5g of hollow glass microspheres were placed in deionized water and ultrasonically cleaned at a frequency of 40kHz for 30 minutes to remove surface impurities and oil. The cleaned hollow glass microspheres were then placed in an 80℃ oven and dried for 2 hours until their quality no longer changed.

[0086] Hollow glass microspheres were modified by adding pretreated hollow glass microspheres to a calcium silicate sol and stirring at 250 rpm for 40 min to ensure uniform dispersion. The mixture was then allowed to stand at room temperature for 24 h to allow the colloidal particles in the sol to fully polymerize and form a gel, which then coats the surface of the hollow glass microspheres. Due to the dense sol network, the gel coating may be relatively thick and have low porosity. The modified hollow glass microspheres were separated by filtration and washed three times with deionized water for 5 min each time. The washed modified hollow glass microspheres were then dried in an oven at 80 °C for 2 h.

[0087] After calcination, the dried modified hollow glass microspheres were evenly spread in a clean ceramic crucible, avoiding excessive accumulation of microspheres which would affect the calcination effect. The ceramic crucible containing the microspheres was placed in a muffle furnace, and the temperature was increased from room temperature to 500℃ at a heating rate of 5℃ / min, and maintained at this temperature for calcination for 3 hours. After calcination, the temperature of the muffle furnace was reduced to room temperature at a cooling rate of 5℃ / min, finally obtaining the finished product of hydrated calcium silicate modified hollow glass microspheres.

[0088] The hydrated calcium silicate modified hollow glass microspheres, cement, and wood fiber are mixed to obtain hydrated calcium silicate modified hollow glass microsphere concrete. In specific applications, concrete is prepared with a ratio of 20 parts hydrated calcium silicate modified hollow glass microspheres, 80 parts cement, and 0.4 parts wood fiber.

[0089] Specifically, in this embodiment, the hollow glass microspheres used are HL20 hollow glass microspheres produced by Zhengzhou Shenglait Hollow Microsphere New Material Co., Ltd. The true density of these HL20 hollow glass microspheres is 0.18 g / cm³ to 0.22 g / cm³, the bulk density is 0.10 g / cm³ to 0.12 g / cm³, the compressive strength is 500 Psi, and the particle size distribution has a D50 of 65 μm and a D90 of 110 μm.

[0090] Specifically, the hydrated calcium silicate modified hollow glass microspheres prepared in Example 9 are hydrated calcium silicate modified hollow glass microspheres with high calcium-to-silicon molar ratio, high hydrolysis temperature, and low acid concentration.

[0091] This embodiment also provides a hydrated calcium silicate modified hollow glass microsphere concrete prepared by the above preparation method. The bulk density of the modified hollow glass microspheres prepared in this embodiment 9 was tested to be 0.131 g / cm³. 3 The compressive strength of the concrete after solidification is 8.2 MPa and the flexural strength is 0.7 MPa.

[0092] Comparative Example 1 In this comparative example, 5g of hollow glass microspheres were placed in deionized water and then ultrasonically cleaned at a frequency of 40kHz for 30 minutes to remove surface impurities and oil. The cleaned hollow glass microspheres were then placed in an oven at 80℃ and dried for 2 hours until their mass no longer changed.

[0093] In practical applications, concrete is prepared by using 20 parts of cleaned and dried hollow glass microspheres, 80 parts of cement, and 0.4 parts of wood fiber.

[0094] The bulk density of the hollow glass microspheres in Comparative Example 1 after cleaning and drying was tested to be 0.107 g / cm³. 3The compressive strength of the concrete after solidification is 5.27 MPa and the flexural strength is 0.49 MPa.

[0095] The test results clearly show that the medium calcium-silicon ratio in Examples 1, 4, and 7 resulted in the best surface modification effect on the microspheres, with the bulk density of the modified hollow glass microspheres increasing to 0.155 g / cm³. 3 The compressive strength of the concrete can reach 11 MPa, and the flexural strength can reach 1.16 MPa.

[0096] Analysis suggests that this is because the calcium-silicon ratio directly affects the equilibrium of hydrolysis and condensation reactions. A low calcium-silicon ratio results in a slow reaction rate and a loose gel structure, while a high calcium-silicon ratio tends to form a silica-rich gel. The gel structure becomes loose again due to the reduced cross-linking degree caused by excessively long silicon chains. When the calcium-silicon ratio is moderate, the reaction rate is fast, and the gel structure becomes dense due to its simple and orderly formation. Ultimately, the gel layer is thick, dense, and has good uniformity.

[0097] Furthermore, it can be seen that in Examples 2, 5, and 8, the moderate hydrolysis temperature is optimal, at which point the bulk density of the modified hollow glass microspheres increases to 0.179 g / cm³. 3 The concrete has a compressive strength of 12.83 MPa and a flexural strength of 1.46 MPa.

[0098] Analysis suggests that this is because higher hydrolysis temperatures accelerate the hydrolysis of precursors such as ethyl silicate. Therefore, at low temperatures, the hydrolysis rate is slow, resulting in a thinner gel layer on the surface of the microspheres with a loose and poorly compact structure. At high temperatures, excessively rapid hydrolysis can easily lead to local aggregation and the formation of byproducts, resulting in uneven gel layer thickness, a loose structure, and overall inhomogeneity. When the temperature is moderate, hydrolysis and condensation are in equilibrium, and the reaction rate is moderate, resulting in a thicker, more uniform gel layer with a denser structure and good homogeneity.

[0099] Furthermore, it can be seen that in Examples 3, 6, and 9, moderate acidity is optimal, at which point the microsphere packing density of the modified hollow glass microspheres increases to 0.163 g / cm³. 3 The concrete has a compressive strength of 11.72 MPa and a flexural strength of 1.22 MPa.

[0100] Analysis suggests that this is because acid concentration directly affects the balance between hydrolysis and condensation. At low acidity, hydrolysis is faster, and the condensation reaction is delayed, resulting in the formation of large polymer molecules. At high acidity, hydrolysis is slower, and the condensation reaction occurs earlier, forming low-crosslinked polymers. High acidity also leads to the formation of byproducts, ultimately resulting in a thinner gel layer, a dense structure, but localized heterogeneity. Medium acidity can balance hydrolysis and condensation, resulting in a stable reaction rate, a moderately thick gel layer, a dense structure, and excellent uniformity.

[0101] Meanwhile, the test results show that after surface modification of hollow microspheres using the calcium silicate sol-gel method, the bulk density of the microspheres increased significantly, and the compressive and flexural strengths of the original hollow microsphere concrete were greatly improved. Example 5 is the best example. Compared with Comparative Example 1, the bulk density of the microspheres increased by 67.3%, the compressive strength of the concrete increased by 143%, and the flexural strength increased by 198%.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method for preparing hydrated calcium silicate modified hollow glass microsphere concrete, comprising the following steps: Calcium silicate sol was reacted with hollow glass microspheres to coat the surface of the hollow glass microspheres with gel, and then calcined to obtain hydrated calcium silicate modified hollow glass microspheres. The hydrated calcium silicate modified hollow glass microspheres, cement, and wood fiber are mixed to obtain hydrated calcium silicate modified hollow glass microsphere concrete.

2. The method for preparing a hydrated calcium silicate modified hollow glass microsphere concrete according to claim 1, characterized in that: The mass ratio of the hydrated calcium silicate modified hollow glass microspheres, the cement, and the wood fiber is (15-25):(75-85):(0.3-0.8).

3. The method for preparing hydrated calcium silicate modified hollow glass microsphere concrete according to claim 1, characterized in that: The ratio of hollow glass microspheres to calcium silicate sol is 5g to 10g of hollow glass microspheres per 100 mL of calcium silicate sol.

4. The method for preparing hydrated calcium silicate modified hollow glass microsphere concrete according to claim 1, 2, or 3, characterized in that: The calcium silicate sol is prepared from a calcium source compound and a silicon source compound, wherein the molar ratio of the calcium source compound to the silicon source compound is (0.5-1.5):

1.

5. The method for preparing hydrated calcium silicate modified hollow glass microsphere concrete according to claim 4, characterized in that: The calcium silicate sol is prepared by the following steps: The calcium source compound and the silicon source compound are mixed and dissolved, and then hydrochloric acid solution is added dropwise to adjust the pH of the solution to 5-6. The reaction is carried out under water bath conditions with stirring to obtain the calcium silicate sol.

6. The method for preparing hydrated calcium silicate modified hollow glass microsphere concrete according to claim 1, characterized in that: The hydrated calcium silicate modified hollow glass microspheres are prepared by the following steps: The hollow glass microspheres were added to the calcium silicate sol, stirred and dispersed, and then allowed to stand at room temperature for aging treatment to allow the colloidal particles in the sol to fully polymerize and form a gel, which coated the surface of the hollow glass microspheres. After filtration, washing, and drying, the temperature was increased from room temperature to 200℃~500℃ at a heating rate of 5℃ / min, and calcined at this temperature for 2h~4h. Then, the temperature was reduced to room temperature at a cooling rate of 5℃ / min to obtain the hydrated calcium silicate modified hollow glass microspheres.

7. The method for preparing hydrated calcium silicate modified hollow glass microsphere concrete according to claim 1, characterized in that: Before reacting the calcium silicate sol with the hollow glass microspheres, the process further includes ultrasonic cleaning and drying of the hollow glass microspheres.

8. A hydrated calcium silicate modified hollow glass microsphere concrete, characterized in that: The hydrated calcium silicate modified hollow glass microsphere concrete is prepared by the preparation method described in any one of claims 1 to 7.