Fly ash-based geopolymer concrete and preparation method thereof

Abstract

The invention discloses fly ash-based geopolymer concrete and a preparation method thereof, and the fly ash-based geopolymer concrete is prepared from the following raw materials in parts by mass: a solid waste cementing material including 60-70 parts of fly ash and 15-30 parts of slag; 2-8 parts of a solid alkali activator; 3-6 parts of carbide slag; the aggregate is prepared from 100 to 120 parts of river sand and 240 to 260 parts of gravel; and 30-45 parts of water. According to the fly ash-based geopolymer concrete disclosed by the embodiment of the invention, carbon dioxide generated in the process of preparing a cementing material can be reduced or avoided, the production cost and the environmental load of the concrete are reduced, the potential activity of the coal-based solid waste can be fully exerted, and meanwhile, the efficient utilization of the fly ash is realized; by introducing the carbide slag and the solid alkali activator, the activity of the fly ash and the slag can be activated, an alkaline environment can be provided, active SiO2 and Al2O3 in the fly ash are subjected to a hydration reaction, hydration products such as C-S-H gel are continuously generated, and the long-term performance of the concrete is more stable.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a fly ash-based polymer concrete and its preparation method. Background Technology

[0002] In the field of architecture and civil engineering, cementitious materials, as core components, play a decisive role in material performance and project quality. Traditional cementitious materials are represented by cement, whose production process is highly dependent on natural mineral resources such as limestone and clay. Moreover, the production of 1 ton of cement clinker is accompanied by the emission of approximately 0.9 tons of carbon dioxide, which not only causes the excessive consumption of non-renewable resources but also becomes a major source of carbon emissions in the construction industry.

[0003] Fly ash and other coal-based solid wastes contain potentially active cementitious components and have been widely studied for use in the preparation of cementitious materials. However, the large-scale application of coal-based solid waste-based cementitious materials still faces multiple bottlenecks in the current technological system: on the one hand, the comprehensive utilization rate of solid waste resources is less than 30%, and a large number of industrial by-products cannot be efficiently utilized due to problems such as low activation efficiency and large fluctuations in composition, leading to secondary problems such as land occupation and environmental pollution from stockpiling; on the other hand, existing solid waste-based cementitious materials generally have defects such as low early strength, poor long-term performance stability, and insufficient durability properties such as impermeability and frost resistance, making it difficult to meet the application requirements of high-performance concrete and special projects.

[0004] Therefore, developing low-cost and environmentally friendly preparation processes has become a key research direction for achieving green and low-carbon transformation in the current building materials field. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of this invention is to propose a fly ash-based polymer concrete, which uses solid waste cementitious materials including fly ash as the cementitious material for the fly ash-based polymer concrete. This can reduce or avoid the carbon dioxide generated during the preparation of the cementitious material, lower the concrete production cost and environmental impact, and fully utilize the potential activity of coal-based solid waste, reducing pollution from industrial waste stockpiling, while simultaneously achieving efficient utilization of fly ash. By introducing carbide slag and solid alkali activators, the activity of fly ash and slag can be activated, and an alkaline environment can be provided, causing the active SiO2 and Al2O3 in the fly ash to undergo hydration reactions, continuously generating hydration products such as CSH gel, resulting in more stable long-term concrete performance.

[0006] The present invention also proposes a method for preparing the above-mentioned fly ash-based polymer concrete.

[0007] According to a first aspect of the present invention, the fly ash-based polymer concrete is made of the following components in parts by weight: solid waste cementitious materials, including 60-70 parts of fly ash and 15-30 parts of slag; 2-8 parts of solid alkali activator; 3-6 parts of calcium carbide slag; aggregates, including 100-120 parts of river sand and 240-260 parts of crushed stone; and 30-45 parts of water.

[0008] According to embodiments of the present invention, the fly ash-based polymer concrete uses solid waste cementitious materials including fly ash as the cementitious material, which can reduce or avoid the carbon dioxide generated during the preparation of the cementitious material, reduce the concrete production cost and environmental impact, and fully utilize the potential activity of coal-based solid waste, reduce industrial waste storage pollution, and achieve efficient utilization of fly ash. By introducing carbide slag and solid alkali activators, the activity of fly ash and slag can be activated, and an alkaline environment can be provided to allow the active SiO2 and Al2O3 in fly ash to undergo hydration reactions, continuously generating hydration products such as CSH gel, making the long-term performance of concrete more stable.

[0009] According to some embodiments of the present invention, the fly ash is Grade II or higher fly ash, and the loss on ignition of the fly ash is ≤5%; and / or, the slag is granulated blast furnace slag, and the slag grade is S95 or higher.

[0010] According to some embodiments of the present invention, the solid alkali activator includes at least one of sodium metasilicate and sodium anhydrous silicate.

[0011] According to some embodiments of the present invention, the carbide slag includes calcium oxide, and the mass percentage of calcium oxide in the carbide slag is ≥60%.

[0012] According to some embodiments of the present invention, the fineness modulus of the river sand is in the range of 2.3-3.0.

[0013] According to some embodiments of the present invention, the crushed stone is continuously graded crushed stone with a particle size range of 5mm-25mm.

[0014] According to a second aspect of the present invention, a method for preparing fly ash-based polymer concrete, wherein the fly ash-based polymer concrete is the fly ash-based polymer concrete according to a first aspect of the present invention, the method for preparing the fly ash-based polymer concrete includes the following steps:

[0015] Step (1): Mix the solid waste cementitious material, the carbide slag, and the solid alkali activator and stir to form a first mixture;

[0016] Step (2): Add the aggregate to the first mixture formed in step (1) and stir to form a second mixture;

[0017] Step (3): Add water to the second mixture formed in step (2) and stir to form a concrete mixture;

[0018] Step (4): Pour the well-mixed concrete mixture into a mold, vibrate it to compact it, and cure it to form the fly ash-based polymer concrete.

[0019] The method for preparing fly ash-based polymer concrete according to an embodiment of the present invention, by mixing and stirring solid waste cementitious materials, carbide slag, and solid alkali activator, can reduce or avoid the carbon dioxide generated during the preparation of cementitious materials, reduce pollution from industrial waste stockpiling, fully utilize the potential activity of coal-based solid waste, achieve efficient utilization of fly ash, reduce concrete production costs and environmental impact, and make the long-term performance of concrete more stable.

[0020] According to some embodiments of the present invention, in step (1), the stirring speed is 25-35 r / min and the stirring time is 1-2 min; and / or, in step (2), the stirring speed is 30-50 r / min and the stirring time is 1-2 min.

[0021] According to some embodiments of the present invention, in step (3), the stirring speed is 55-75 r / min and the stirring time is 3-5 min.

[0022] According to some embodiments of the present invention, in step (4), the curing conditions are a temperature of 20±2℃, a relative humidity of ≥95%, and a curing period of not less than 28 days.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 This is a method for preparing fly ash-based polymer concrete according to some embodiments of the present invention. Detailed Implementation

[0026] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0027] The following is for reference. Figure 1 A fly ash-based polymer concrete is described according to an embodiment of the present invention.

[0028] According to a first aspect embodiment of the fly ash-based polymer concrete, the raw materials for producing the fly ash-based polymer concrete include the following components in parts by weight:

[0029] Solid waste cementitious materials, including 60-70 parts fly ash and 15-30 parts slag;

[0030] 2-8 parts of solid alkali activator;

[0031] 3-6 parts of calcium carbide slag;

[0032] Aggregates, including 100-120 parts river sand and 240-260 parts crushed stone;

[0033] 30-45 parts water.

[0034] Each of these portions contains materials of the same weight.

[0035] By including 60-70 parts fly ash in the solid waste cementitious material, the potential activity of coal-based solid waste can be fully utilized, fly ash can be fully utilized, secondary problems such as land occupation and environmental pollution caused by fly ash storage can be alleviated, and the comprehensive utilization rate of solid waste resources can be improved. In addition, carbon dioxide generated during the preparation of cementitious materials can be reduced or avoided, thus reducing carbon emissions, concrete production costs and environmental impact.

[0036] For example, fly ash accounts for more than 60% of the mass content in solid waste cementitious materials.

[0037] By including alkali activators in the raw materials for fly ash-based polymer concrete, the alkali activators can activate the activity of fly ash and slag, promote the formation of a network structure between fly ash and slag, enhance the cementing effect of fly ash and slag, and provide an alkaline environment to cause the active SiO2 and Al2O3 in fly ash to undergo hydration reactions, continuously generating hydration products such as CSH gel. Because the reaction rate is relatively slow, CSH gel can be continuously generated long after the concrete has been cured, making the long-term performance of the concrete more stable.

[0038] By including carbide slag in the raw materials for fly ash-based polymer concrete, the carbide slag can work synergistically with solid alkali activators to activate the activity of fly ash and slag. Under the condition that the activation capacity of fly ash and slag is the same, carbide slag can replace part of the solid alkali activator, reducing the amount of solid alkali activator used, which can further reduce the cost of concrete.

[0039] According to embodiments of the present invention, the fly ash-based polymer concrete uses solid waste cementitious materials including fly ash as the cementitious material, which can reduce or avoid the carbon dioxide generated during the preparation of the cementitious material, reduce the concrete production cost and environmental impact, and fully utilize the potential activity of coal-based solid waste, reduce industrial waste storage pollution, and achieve efficient utilization of fly ash. By introducing carbide slag and solid alkali activators, the activity of fly ash and slag can be activated, and an alkaline environment can be provided to allow the active SiO2 and Al2O3 in fly ash to undergo hydration reactions, continuously generating hydration products such as CSH gel, making the long-term performance of concrete more stable.

[0040] According to some embodiments of the present invention, the fly ash is Grade II or higher fly ash, and the loss on ignition of the fly ash is ≤5%. By making the fly ash Grade II or higher fly ash, the quality of solid waste cementitious materials can be improved; by making the loss on ignition of the fly ash ≤5%, the stability of solid waste cementitious materials can be improved.

[0041] According to some embodiments of the present invention, the slag is granulated blast furnace slag, and the slag grade is S95 or higher. By making the slag grade S95 or higher, the quality of solid waste cementitious materials can be improved.

[0042] According to some embodiments of the present invention, the solid alkali activator includes at least one of sodium metasilicate and sodium anhydrous silicate. By including at least one of sodium metasilicate and sodium anhydrous silicate in the solid alkali activator, an alkaline environment can be provided, causing the active SiO2 and Al2O3 in fly ash to undergo hydration reactions, continuously generating hydration products such as CSH gel, thus making the long-term performance of concrete more stable. Furthermore, by using the solid form of the alkali activator, spillage during use can be avoided, preventing injury to people or other facilities, making the use process safer.

[0043] According to some embodiments of the present invention, the carbide slag includes calcium oxide, and the mass percentage of calcium oxide in the carbide slag is ≥60%. Calcium oxide can provide calcium ions for the reaction and can also provide an alkaline environment to promote the hydration reaction of SiO2 and Al2O3 in fly ash to form a gel.

[0044] According to some embodiments of the present invention, the fineness modulus of the river sand is in the range of 2.3-3.0. By making the fineness modulus of the river sand in the range of 2.3-3.0, the performance of the concrete can be improved.

[0045] According to some embodiments of the present invention, the crushed stone is continuously graded crushed stone with a particle size range of 5mm-25mm. By using continuously graded crushed stone with a particle size range of 5mm-25mm, the performance of the concrete can be improved.

[0046] Reference Figure 1According to a second aspect of the present invention, a method for preparing fly ash-based polymer concrete is provided, wherein the fly ash-based polymer concrete is the fly ash-based polymer concrete according to a first aspect of the present invention, and the method for preparing fly ash-based polymer concrete includes the following steps:

[0047] Step (1): Mix solid waste cementitious material, carbide slag, and solid alkali activator to form a first mixture;

[0048] Step (2): Add aggregate to the first mixture formed in step (1) and stir to form a second mixture;

[0049] Step (3): Add water to the second mixture formed in step (2) and stir to form a concrete mixture;

[0050] Step (4): Pour the mixed concrete mixture into the mold, vibrate it to make it dense, and cure it to form fly ash-based polymer concrete.

[0051] By mixing and stirring solid waste cementitious materials, carbide slag, and solid alkali activator to form a first mixture, the solid alkali activator can provide an alkaline environment for the solid waste cementitious materials, causing the active SiO2 and Al2O3 in fly ash to undergo hydration reactions and continuously generate hydration products such as CSH gel, making the long-term performance of concrete more stable. Carbide slag can work together with the solid alkali activator to activate the activity of fly ash and slag, and improve the cementing ability of solid waste cementitious materials.

[0052] For example, tools can be used to mix and stir solid alkaline activators with solid waste cementitious materials and carbide slag. Compared with the direct dumping of liquid alkaline chemicals in related technologies, this can reduce the risk of alkaline chemicals harming people or other facilities during the dumping process and improve safety.

[0053] The method for preparing fly ash-based polymer concrete according to embodiments of the present invention, by mixing and stirring solid waste cementitious materials, carbide slag, and solid alkali activator, can reduce or avoid the carbon dioxide generated during the preparation of cementitious materials, reduce pollution from industrial waste stockpiling, fully utilize the potential activity of coal-based solid waste, achieve efficient utilization of fly ash, reduce concrete production costs and environmental impact, and make the long-term performance of concrete more stable.

[0054] Reference Figure 1 According to some embodiments of the present invention, in step (1), the stirring speed is 25-35 r / min and the stirring time is 1-2 min. By making the stirring speed in step (1) 25-35 r / min and the stirring time 1-2 min, the mixing between the solid waste cementitious material and the carbide slag and solid alkali activator can be more thorough and uniform.

[0055] Reference Figure 1 According to some embodiments of the present invention, in step (2), the stirring speed is 30-50 r / min and the stirring time is 1-2 min. By setting the stirring speed in step (2) to 30-50 r / min and the stirring time to 1-2 min, the mixing between the first mixture and the aggregate can be more thorough.

[0056] Reference Figure 1 According to some embodiments of the present invention, in step (3), the stirring speed is 55-75 r / min and the stirring time is 3-5 min. By setting the stirring speed in step (3) to 55-75 r / min and the stirring time to 3-5 min, the second mixture can be mixed more thoroughly with water to form concrete.

[0057] Reference Figure 1 According to some embodiments of the present invention, in step (4), the curing conditions are a temperature of 20±2℃, a relative humidity of ≥95%, and a curing period of not less than 28 days. By setting the curing conditions to a temperature of 20±2℃, a relative humidity of ≥95%, and a curing period of not less than 28 days, the normal hardening of the concrete can be guaranteed.

[0058] The following examples further illustrate the fly ash-based polymer concrete and its preparation method according to embodiments of the present invention.

[0059] Example 1

[0060] Step (1): Weigh the raw materials according to the following mass ratios: fly ash 65, slag 25, alkali activator 6, and carbide slag 4. Pour them into the mixing equipment and mix for 1 minute at a mixing speed of 30 r / min.

[0061] Step (2): Add 110 parts river sand and 250 parts gravel, and continue stirring for 1 minute at a stirring speed of 40 r / min;

[0062] Step (3): Slowly add 32 parts of water to the above mixture and stir for 4 minutes at a stirring speed of 60 r / min.

[0063] Step (4): Pour the concrete mixture into a 150mm×150mm×150mm cube mold, vibrate it to compact it, and then cure it for 28 days in a curing room with a temperature of 20℃ and a relative humidity of over 95%.

[0064] After the curing period, the concrete test blocks were subjected to performance tests. The results showed that the 28-day compressive strength of the concrete was 34.9 MPa, the 60-day compressive strength was 36.8 MPa, and the 90-day compressive strength was 37.2 MPa.

[0065] Example 2

[0066] Step (1): Weigh the raw materials according to the following mass ratios: fly ash 65, slag 25, alkali activator 6, and carbide slag 4. Pour them into the mixing equipment and mix for 1 minute at a mixing speed of 30 r / min.

[0067] Step (2): Add 110 parts river sand and 250 parts gravel, and continue stirring for 1 minute at a stirring speed of 40 r / min;

[0068] Step (3): Slowly add 40 parts of water to the above mixture and stir for 4 minutes at a stirring speed of 60 r / min.

[0069] Step (4): Pour the concrete mixture into a 150mm×150mm×150mm cube mold, vibrate it to compact it, and then cure it for 28 days in a curing room with a temperature of 20℃ and a relative humidity of over 95%.

[0070] After the curing period, the concrete test blocks were subjected to performance tests. The results showed that the 28-day compressive strength of the concrete was 33.7 MPa.

[0071] Example 3

[0072] Step (1): Weigh the raw materials according to the following mass ratios: fly ash 70, slag 21, alkali activator 6, and carbide slag 3. Pour them into the mixing equipment and mix for 1 minute at a mixing speed of 30 r / min.

[0073] Step (2): Add 110 parts river sand and 250 parts gravel, and continue stirring for 1 minute at a stirring speed of 40 r / min;

[0074] Step (3): Slowly add 32 parts of water to the above mixture and stir for 4 minutes at a stirring speed of 60 r / min.

[0075] Step (4): Pour the concrete mixture into a 150mm×150mm×150mm cube mold, vibrate it to compact it, and then cure it for 28 days in a curing room with a temperature of 20℃ and a relative humidity of over 95%.

[0076] After the curing period, the concrete test blocks were subjected to performance tests. The results showed that the 28-day compressive strength of the concrete was 21.9 MPa.

[0077] Example 4

[0078] Step (1): Weigh the raw materials according to the following mass ratios: fly ash 70, slag 18, alkali activator 6, carbide slag 6. Pour them into the mixing equipment and mix for 1 minute at a mixing speed of 30 r / min.

[0079] Step (2): Then add 110 parts river sand and 250 parts gravel, and continue stirring for 1 minute at a stirring speed of 40 r / min.

[0080] Step (3): Slowly add 32 parts of water to the above mixture and stir for 4 minutes at a stirring speed of 60 r / min.

[0081] Step (4): Pour the concrete mixture into a 150mm×150mm×150mm cube mold, vibrate it to compact it, and then cure it for 28 days in a curing room with a temperature of 20℃ and a relative humidity of over 95%.

[0082] After the curing period, the concrete test blocks were subjected to performance tests. The results showed that the 28-day compressive strength of the concrete was 35.6 MPa.

[0083] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0084] In the description of this invention, "first feature" and "second feature" may include one or more of the features.

[0085] In the description of this invention, "a plurality of" means two or more.

[0086] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0087] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0088] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0089] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A fly ash-based polymer concrete, characterized in that, The raw materials for the fly ash-based polymer concrete include the following components in parts by weight: Solid waste cementitious materials, including 60-70 parts fly ash and 15-30 parts slag; 2-8 parts of solid alkali activator; 3-6 parts of calcium carbide slag; Aggregates, including 100-120 parts river sand and 240-260 parts crushed stone; 30-45 parts water.

2. The fly ash-based polymer concrete according to claim 1, characterized in that, The fly ash is Grade II or above, and the loss on ignition of the fly ash is ≤5%; and / or, the slag is granulated blast furnace slag, and the slag grade is S95 or above.

3. The fly ash-based polymer concrete according to claim 1, characterized in that, The solid alkali activator includes at least one of sodium metasilicate and sodium anhydrous silicate.

4. The fly ash-based polymer concrete according to claim 1, characterized in that, The carbide slag includes calcium oxide, and the mass percentage of calcium oxide in the carbide slag is ≥60%.

5. The fly ash-based polymer concrete according to claim 1, characterized in that, The fineness modulus of the river sand is in the range of 2.3-3.

0.

6. The fly ash-based polymer concrete according to claim 1, characterized in that, The crushed stone is continuously graded crushed stone with a particle size range of 5mm-25mm.

7. A method for preparing fly ash-based polymer concrete, characterized in that, The fly ash-based polymer concrete is the fly ash-based polymer concrete according to any one of claims 1-6, and the preparation method of the fly ash-based polymer concrete includes the following steps: Step (1): Mix the solid waste cementitious material, the carbide slag, and the solid alkali activator and stir to form a first mixture; Step (2): Add the aggregate to the first mixture formed in step (1) and stir to form a second mixture; Step (3): Add water to the second mixture formed in step (2) and stir to form a concrete mixture; Step (4): Pour the well-mixed concrete mixture into a mold, vibrate it to compact it, and cure it to form the fly ash-based polymer concrete.

8. The method for preparing fly ash-based polymer concrete according to claim 7, characterized in that, In step (1), the stirring speed is 25-35 r / min and the stirring time is 1-2 min; and / or, in step (2), the stirring speed is 30-50 r / min and the stirring time is 1-2 min.

9. The method for preparing fly ash-based polymer concrete according to claim 7, characterized in that, In step (3), the stirring speed is 55-75 r / min and the stirring time is 3-5 min.

10. The method for preparing fly ash-based polymer concrete according to claim 7, characterized in that, In step (4), the curing conditions are a temperature of 20±2℃, a relative humidity of ≥95%, and a curing period of no less than 28 days.

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