A rapid prototyping geopolymer concrete precast component and a method of making the same

Abstract

The application relates to a rapid-forming geopolymer concrete prefabricated component and a preparation method thereof. The technical scheme is as follows: 125-150 parts by mass of sodium metasilicate is mixed with 200-235 parts by mass of water to obtain a solution; the solution is stirred until it is clear, and is cooled to 5-15 DEG C to obtain an alkali activator; the alkali activator is mixed with 225-285 parts by mass of metakaolin, 60-120 parts by mass of fly ash, 400-600 parts by mass of fine aggregate and 550-850 parts by mass of coarse aggregate, is stirred, is poured, and is shaped for 10-30 min; demolding is carried out, and maintenance is carried out at normal temperature for 2-7 days to obtain the rapid-forming geopolymer concrete prefabricated component. The application has the characteristics of high solid waste resource utilization rate, short forming time, low maintenance cost and high mold flow efficiency, can be directly operated on a construction site and can be rapidly and continuously produced, and the prepared rapid-forming geopolymer concrete prefabricated component has early compressive strength.

Description

Technical Field

[0001] This invention belongs to the technical field of precast concrete components. Specifically, it relates to a rapid-molding geopolymer precast concrete component and its preparation method. Background Technology

[0002] Precast components are construction parts that, through precise planning and design, divide a building into standardized components, such as beams, columns, and walls, that can be manufactured off-site. After these components are manufactured in a factory at another location, they are transported to the construction site for crane piling and assembly. The production process of precast components mainly includes module assembly, placement of embedded parts, pouring of raw materials, curing, and storage.

[0003] The patented technology of "Geopolymer Concrete Precast Components and Their Production Method" (CN106336158A) uses raw materials such as slag powder, fly ash, silica fume, gravel and medium sand mixed in a certain proportion to produce precast components. Although this technology realizes the resource utilization of solid waste and has good flexural and compressive strength, it requires finishing and steam curing in sequence, with a curing time of about 2 to 8 hours. In addition, the molding time is long, it does not have early compressive strength, and the turnover efficiency of the mold is low.

[0004] The patented technology "Concrete powder, concrete, precast concrete components and their application in building construction" (CN11875308A) mixes cementitious materials, ceramic particles, ceramic powder, water-reducing agents and fly ash in a certain proportion to produce precast door jambs, door frames and door beams. It requires curing at 20℃ and 95% relative humidity for 24 hours before demolding. Although it has the advantages of light weight and high compressive strength, its molding time is long, it does not have early compressive strength, its application scenarios are relatively limited, and it reduces the turnover efficiency of the mold.

[0005] The patented technology, "A method for preparing low-carbon, rapid-release precast components made from solid waste-based cementitious materials containing cement, fly ash, and desulfurized gypsum," (CN115448680A), utilizes low-volume cement and high-volume fly ash combined with desulfurized gypsum to prepare precast components. This technology promotes the application of solid waste to some extent, but it requires high curing conditions, including 4 hours of standard curing, 8 to 20 hours of high-temperature curing, and subsequent standard curing. It also suffers from long molding time and lack of early compressive strength.

[0006] In summary, the current production of precast components suffers from long molding times, generally exceeding 10 hours, lack of early compressive strength, the need for steam or high-temperature curing, and low mold turnover efficiency. Summary of the Invention

[0007] The present invention aims to overcome the defects of the prior art and provides a method for preparing rapidly prototyping geopolymer concrete precast components. This method has a high solid waste resource utilization rate, short molding time, low maintenance cost and high mold turnover efficiency. It can be directly operated on the construction site and carried out rapid and continuous production. The rapidly prototyping geopolymer concrete precast components prepared have early compressive strength.

[0008] To achieve the above objectives, the specific steps of the technical solution adopted by the present invention are as follows:

[0009] Step 1: Mix 125-150 parts by weight of sodium metasilicate with 200-235 parts by weight of water to obtain a solution; stir the solution until it becomes clear, and then cool the stirred solution to 5-15°C to obtain an alkaline activator.

[0010] Step 2: Mix the alkali activator with 225-285 parts by weight of metakaolin, 60-120 parts by weight of fly ash, 400-600 parts by weight of fine aggregate and 550-850 parts by weight of coarse aggregate, and stir to obtain geopolymer concrete mixture.

[0011] Step 3: Pour the geopolymer concrete mixture into a mold, and the molding time is 10-30 minutes. Demold the mixture to obtain the initial precast component. Then, cure the initial precast component at room temperature for 2-7 days to obtain the rapidly formed geopolymer concrete precast component.

[0012] The sodium metasilicate contains 44–47 wt% SiO2.

[0013] The cooling rate is 0.5–3.0 °C / min.

[0014] The metakaolin clay has a SiO2 content of 45–60 wt% and an Al2O3 content of 30–50 wt%.

[0015] The fly ash meets the requirements of "Fly Ash for Cement and Concrete" (GB / T 1596-2017).

[0016] The fine aggregate meets the requirements of "Recycled Fine Aggregate for Concrete and Mortar" (GB / T 25176-2010).

[0017] The coarse aggregate meets the requirements of "Recycled Coarse Aggregate for Concrete and Mortar" (GB / T 25177-2010).

[0018] The stirring speed in step one is 150-600 r / min; the stirring speed in step two is 1600-2200 r / min.

[0019] By adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0020] 1. This invention uses low-temperature cooling of the alkali activator to suppress the rapid initial reaction between the alkali activator and the raw materials. After mixing with metakaolin, fly ash, fine aggregate, and coarse aggregate, the low-temperature environment and the crystallization tendency provided by metakaolin facilitate the rapid formation of hydrated crystals (such as Na2SiO3·9H2O, Na2SiO3·8H2O) that encapsulate the raw materials, enabling rapid hardening of the precast components in the initial stage. The hardening time is 15–30 minutes, significantly shortening the molding time. Furthermore, it eliminates the need for steam or high-temperature curing, resulting in low curing costs. According to GB / T 50081 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", the compressive strength of the precast components in the initial stage is 3.41–6.21 MPa.

[0021] 2. In this invention, the alkali activator and raw materials such as metakaolin, fly ash, fine aggregate, and coarse aggregate are well dispersed during the mixing process. After crystallization, sodium silicate can continue to undergo geopolymerization reaction with the raw materials at room temperature. The precast components are then cured at room temperature for 2 to 7 days to obtain rapidly formed geopolymer concrete precast components. According to GB / T 50081 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", the compressive strength after curing is 15.96 to 30.48 MPa.

[0022] 3. This invention uses fly ash, fine aggregate, and coarse aggregate mixed with alkali activator and metakaolin, which improves the resource utilization rate of solid waste and is environmentally friendly. Due to the fast molding speed and early compressive strength, the turnover efficiency of the mold is improved. In addition, this invention is cured at room temperature, without the need for high-temperature curing, which reduces curing costs and saves energy.

[0023] 4. This invention enables rapid and continuous production in factories and can also be used in construction site operations, reducing production costs caused by off-site transportation and error tolerance, and improving construction efficiency.

[0024] Therefore, this invention has the characteristics of high solid waste resource utilization rate, short molding time, low maintenance cost and high mold turnover efficiency. It can be directly operated on the construction site and carried out rapid and continuous production. The rapidly molded geopolymer concrete precast components prepared have early compressive strength. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments, but this is not intended to limit the scope of protection thereof:

[0026] A rapid-formation precast polymer concrete component and its preparation method. The preparation method described in this specific embodiment is as follows:

[0027] Step 1: Mix 125-150 parts by weight of sodium metasilicate with 200-235 parts by weight of water to obtain a solution; stir the solution until it becomes clear, and then cool the stirred solution to 5-15°C to obtain an alkaline activator.

[0028] Step 2: Mix the alkali activator with 225-285 parts by weight of metakaolin, 60-120 parts by weight of fly ash, 400-600 parts by weight of fine aggregate and 550-850 parts by weight of coarse aggregate, and stir to obtain geopolymer concrete mixture.

[0029] Step 3: Pour the geopolymer concrete mixture into a mold, and the molding time is 10-30 minutes. Demold the mixture to obtain the initial precast component. Then, cure the initial precast component at room temperature for 2-7 days to obtain the rapidly formed geopolymer concrete precast component.

[0030] The sodium metasilicate contains 44–47 wt% SiO2.

[0031] The cooling rate is 0.5–3.0 °C / min.

[0032] The metakaolin clay has a SiO2 content of 45–60 wt% and an Al2O3 content of 30–50 wt%.

[0033] The stirring speed in step one is 150-600 r / min; the stirring speed in step two is 1600-2200 r / min.

[0034] In this specific implementation:

[0035] The fly ash meets the requirements of "Fly Ash for Cement and Concrete" (GB / T 1596-2017).

[0036] The fine aggregate meets the requirements of "Recycled Fine Aggregate for Concrete and Mortar" (GB / T 25176-2010).

[0037] The coarse aggregate meets the requirements of "Recycled Coarse Aggregate for Concrete and Mortar" (GB / T 25177-2010).

[0038] The details will not be repeated in the examples.

[0039] Example 1

[0040] A rapid-formation precast polymer concrete component and its preparation method. The preparation method described in this specific embodiment is as follows:

[0041] Step 1: Mix 125 parts by mass of sodium metasilicate with 200 parts by mass of water to obtain a solution; stir the solution until it becomes clear, and then cool the stirred solution to 5°C to obtain an alkaline activator.

[0042] Step 2: Mix the alkali activator with 225 parts by weight of metakaolin, 60 parts by weight of fly ash, 400 parts by weight of fine aggregate and 550 parts by weight of coarse aggregate, and stir to obtain geopolymer concrete mixture.

[0043] Step 3: Pour the geopolymer concrete mixture into a mold, and demold it for 10 minutes to obtain the initial precast component; then cure the initial precast component at room temperature for 7 days to obtain the rapidly formed geopolymer concrete precast component.

[0044] The sodium metasilicate contains 47 wt% SiO2.

[0045] The cooling rate is 0.5℃ / min.

[0046] The metakaolin clay has a SiO2 content of 55 wt% and an Al2O3 content of 35 wt%.

[0047] The stirring speed in step one is 600 r / min; the stirring speed in step two is 2200 r / min.

[0048] According to the test results of this embodiment, the compressive strength of the initial precast component is 6.21 MPa; the compressive strength after curing is 30.48 MPa.

[0049] Example 2

[0050] A rapid-formation precast polymer concrete component and its preparation method. The preparation method described in this specific embodiment is as follows:

[0051] Step 1: Mix 135 parts by mass of sodium metasilicate with 210 parts by mass of water to obtain a solution; stir the solution until it becomes clear, and then cool the stirred solution to 9°C to obtain an alkaline activator.

[0052] Step 2: Mix the alkali activator with 245 parts by weight of metakaolin, 75 parts by weight of fly ash, 470 parts by weight of fine aggregate and 650 parts by weight of coarse aggregate, and stir to obtain geopolymer concrete mixture.

[0053] Step 3: Pour the geopolymer concrete mixture into a mold, and demold it after 16 minutes to obtain the initial precast component; then cure the initial precast component at room temperature for 5 days to obtain the rapidly formed geopolymer concrete precast component.

[0054] The sodium metasilicate contains 46 wt% SiO2.

[0055] The cooling rate is 1.0℃ / min.

[0056] The metakaolin clay has a SiO2 content of 60 wt% and an Al2O3 content of 30 wt%.

[0057] The stirring speed in step one is 450 r / min; the stirring speed in step two is 2000 r / min.

[0058] According to the test results of this embodiment, the compressive strength of the initial precast component is 5.63 MPa; the compressive strength after curing is 25.37 MPa.

[0059] Example 3

[0060] A rapid-formation precast polymer concrete component and its preparation method. The preparation method described in this specific embodiment is as follows:

[0061] Step 1: Mix 140 parts by mass of sodium metasilicate with 220 parts by mass of water to obtain a solution; stir the solution until it becomes clear, and then cool the stirred solution to 12°C to obtain an alkaline activator.

[0062] Step 2: Mix the alkali activator with 260 parts by weight of metakaolin, 95 parts by weight of fly ash, 530 parts by weight of fine aggregate and 745 parts by weight of coarse aggregate, and stir to obtain geopolymer concrete mixture.

[0063] Step 3: Pour the geopolymer concrete mixture into a mold, and demold it after 22 minutes to obtain the initial precast component; then cure the initial precast component at room temperature for 3 days to obtain the rapidly formed geopolymer concrete precast component.

[0064] The sodium metasilicate contains 45 wt% SiO2.

[0065] The cooling rate is 2.0℃ / min.

[0066] The metakaolin clay has a SiO2 content of 50 wt% and an Al2O3 content of 40 wt%.

[0067] The stirring speed in step one is 250 r / min; the stirring speed in step two is 1800 r / min.

[0068] According to the test results of this embodiment, the compressive strength of the initial precast component is 4.28 MPa; the compressive strength after curing is 21.45 MPa.

[0069] Example 4

[0070] A rapid-formation precast polymer concrete component and its preparation method. The preparation method described in this specific embodiment is as follows:

[0071] Step 1: Mix 150 parts by mass of sodium metasilicate with 235 parts by mass of water to obtain a solution; stir the solution until it becomes clear, and then cool the stirred solution to 15°C to obtain an alkaline activator.

[0072] Step 2: Mix the alkali activator with 285 parts by weight of metakaolin, 120 parts by weight of fly ash, 600 parts by weight of fine aggregate and 850 parts by weight of coarse aggregate, and stir to obtain geopolymer concrete mixture.

[0073] Step 3: Pour the geopolymer concrete mixture into a mold, and demold it for 30 minutes to obtain the initial precast component; then cure the initial precast component at room temperature for 2 days to obtain the rapidly formed geopolymer concrete precast component.

[0074] The sodium metasilicate contains 44 wt% SiO2.

[0075] The cooling rate is 3.0℃ / min.

[0076] The metakaolin clay has a SiO2 content of 45 wt% and an Al2O3 content of 50 wt%.

[0077] The stirring speed in step one is 150 r / min; the stirring speed in step two is 1600 r / min.

[0078] According to the test results of this embodiment, the compressive strength of the initial precast component is 3.41 MPa; the compressive strength after curing is 15.96 MPa.

[0079] This specific implementation method has the following advantages compared with the prior art:

[0080] 1. This specific embodiment uses low-temperature cooling of the alkali activator to suppress the rapid initial reaction between the alkali activator and the raw materials. After mixing with metakaolin, fly ash, fine aggregate, and coarse aggregate, the low-temperature environment and the crystallization tendency provided by metakaolin facilitate the rapid formation of hydrated crystals (such as Na2SiO3·9H2O, Na2SiO3·8H2O) that encapsulate the raw materials, achieving rapid hardening of the precast components in the initial stage. The hardening and molding time is 15–30 minutes, significantly shortening the molding time. Furthermore, no steam or high-temperature curing is required, resulting in low curing costs. According to GB / T 50081 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", the compressive strength of the precast components in the initial stage is 3.41–6.21 MPa.

[0081] 2. In this specific embodiment, the alkali activator and raw materials such as metakaolin, fly ash, fine aggregate, and coarse aggregate are well dispersed during the mixing process. After crystallization, sodium silicate can continue to undergo geopolymerization reaction with the raw materials at room temperature. The precast components are then cured at room temperature for 2 to 7 days to obtain rapidly formed geopolymer concrete precast components. According to GB / T50081 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", the compressive strength after curing is 15.96 to 30.48 MPa.

[0082] 3. This specific embodiment uses fly ash, fine aggregate, and coarse aggregate mixed with alkali activator and metakaolin, which improves the resource utilization rate of solid waste and is environmentally friendly; due to the fast molding speed and early compressive strength, the turnover efficiency of the mold is improved; in addition, this specific embodiment is cured at room temperature, without the need for high-temperature curing, resulting in low curing cost and energy saving.

[0083] 4. This specific implementation method can achieve rapid continuous production in the factory and can also be used for on-site construction operations, reducing the production costs caused by off-site transportation and error tolerance, and improving construction efficiency.

[0084] Therefore, this specific implementation method has the characteristics of high solid waste resource utilization rate, short molding time, low maintenance cost and high mold turnover efficiency. It can be directly operated on the construction site and carried out rapid and continuous production. The rapidly molded geopolymer concrete precast components prepared have early compressive strength.

Claims

1. A method for preparing rapidly prototyping precast polymer concrete components, characterized in that... The specific steps of the preparation method are as follows: Step 1: Mix 125-150 parts by weight of sodium metasilicate with 200-235 parts by weight of water to obtain a solution; stir the solution until it becomes clear, and then cool the stirred solution to 5-15°C to obtain an alkaline activator. Step 2: Mix the alkali activator with 225-285 parts by weight of metakaolin, 60-120 parts by weight of fly ash, 400-600 parts by weight of fine aggregate and 550-850 parts by weight of coarse aggregate, and stir to obtain geopolymer concrete mixture. Step 3: Pour the geopolymer concrete mixture into a mold, and the molding time is 10-30 minutes. Demold the mixture to obtain the initial precast component. Then, cure the initial precast component at room temperature for 2-7 days to obtain the rapidly formed geopolymer concrete precast component.

2. The method for preparing rapidly prototyping precast geopolymer concrete components according to claim 1, characterized in that... The sodium metasilicate contains 44–47 wt% SiO2.

3. The method for preparing rapidly prototyping precast geopolymer concrete components according to claim 1, characterized in that... The cooling rate is 0.5–3.0 °C / min.

4. The method for preparing rapidly prototyping precast geopolymer concrete components according to claim 1, characterized in that... The metakaolin clay has a SiO2 content of 45–60 wt% and an Al2O3 content of 30–50 wt%.

5. The method for preparing rapidly prototyping precast geopolymer concrete components according to claim 1, characterized in that... The fly ash meets the requirements of "Fly Ash for Cement and Concrete" (GB / T 1596-2017).

6. The method for preparing rapidly prototyping precast geopolymer concrete components according to claim 1, characterized in that... The fine aggregate meets the requirements of "Recycled Fine Aggregate for Concrete and Mortar" (GB / T 25176-2010).

7. The method for preparing rapidly prototyping precast geopolymer concrete components according to claim 1, characterized in that... The coarse aggregate meets the requirements of "Recycled Coarse Aggregate for Concrete and Mortar" (GB / T 25177-2010).

8. The method for preparing rapidly prototyping precast geopolymer concrete components according to claim 1, characterized in that... The stirring speed in step one is 150-600 r / min; the stirring speed in step two is 1600-2200 r / min.

9. A rapidly prototyping precast polymer concrete component, characterized in that... The rapidly prototyping precast geopolymer concrete component is a rapidly prototyping precast geopolymer concrete component prepared by the preparation method of the rapidly prototyping precast geopolymer concrete component according to any one of claims 1 to 8.