A composite gel-physical foaming synergistic carbon dioxide foam concrete and a preparation process thereof

Abstract

The application discloses a kind of composite gel-physical foaming synergistic carbon dioxide foam concrete preparation process, carbon dioxide foam concrete, by mass parts, consisting of following components: sulphate cement 15-45 parts, hemihydrate gypsum 10-50 parts, Portland cement 5-15 parts, mineral powder 0-30 parts, gypsum retarder 0-0.3 parts, retarder 0.2-0.4 parts, water reducing agent 0.2-0.4 parts, calcium stearate 0.2-0.6 parts, hydroxypropyl methylcellulose ether (HPMC) 0.1-0.3 parts, water-cement ratio 0.2-0.45, prefabricated foam 5-15 parts.Sulphate cement, Portland cement and hemihydrate gypsum are mixed to prepare carbon dioxide foam concrete when specific mass ratio, can play the hydration synergistic effect between three, and then can greatly improve the mechanical properties of carbon dioxide foam concrete.

Description

Technical Field

[0001] This invention belongs to the field of green, low-carbon, and zero-carbon building materials technology, specifically relating to a composite gel-physical foaming synergistic carbon dioxide foam concrete and its preparation process. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Currently, the cementitious materials used in the preparation of carbon dioxide foamed concrete are mainly silicate cement and sulfoaluminate cement, with the addition of mineral admixtures such as fly ash, mineral powder, and carbide slag. Carbon dioxide is introduced through physical or chemical methods, and the material is prepared at a relatively high water-cement ratio. The main parameters to consider in carbon dioxide foamed concrete are density, compressive strength, thermal conductivity, porosity, and water absorption. However, under conventional preparation processes, carbon dioxide foamed concrete suffers from problems such as high density, low compressive strength, and strength provided by a single type of cement. The density of foamed concrete is positively correlated with its compressive strength; a decrease in density inevitably leads to a decrease in compressive strength. Therefore, achieving high compressive strength must still consider the requirement for low density and lightweight. Both lightweight, low density, and high compressive strength are beneficial for foamed concrete. While high water-cement ratios and high carbon dioxide concentrations increase porosity and carbonation rate, it is difficult to simultaneously achieve both lightweight and high strength requirements in carbon dioxide foamed concrete.

[0004] Therefore, the mechanism of action of the existing cementitious system is not comprehensive and the interaction between various minerals needs to be explored in depth. Furthermore, it does not consider the reaction between CO2 and the cementitious system and further enhance its positive effect on the performance of foamed concrete. It also cannot meet the demand for lighter foamed concrete materials and achieve the goal of rapid curing and foam stabilization. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a process for preparing carbon dioxide foam concrete that combines composite gel and physical foaming.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] In a first aspect, the present invention provides a composite gel-physical foaming synergistic carbon dioxide foam concrete, which, by mass parts, is composed of the following components:

[0008] 15-45 parts sulfoaluminate cement, 10-50 parts hemihydrate gypsum, 5-15 parts silicate cement, 1-30 parts mineral powder, 0-0.3 parts gypsum retarder, 0.2-0.4 parts retarder, 0.2-0.4 parts water-reducing agent, 0.2-0.6 parts calcium stearate, 0.1-0.3 parts hydroxypropyl methylcellulose ether (HPMC), water-cement ratio 0.2-0.45, and 5-15 parts precast foam.

[0009] The strength of existing carbon dioxide foamed concrete materials mainly comes from cement. Adding other mineral admixtures primarily aims to enhance the material's strength, thus somewhat weakening the requirement for lightweight properties. The effect of the reaction between CO2 and the cementitious system on the performance enhancement of foamed concrete is not considered. A high water-cement ratio is beneficial for mineralization reactions, but at a high water-cement ratio, some strength properties are sacrificed, making it difficult for carbon dioxide foamed concrete materials to meet industrial requirements. Existing research attempts to increase the carbon sequestration of concrete at the material level by increasing the carbon dioxide concentration; however, high-concentration carbon dioxide foam is extremely unstable, and rapid solidification and shaping of carbon dioxide foam is difficult to achieve at high concentrations.

[0010] Hemihydrate gypsum has the composition CaSO4·0.5H2O, a monoclinic crystal system, and its crystals are microscopic needle-like. Hemihydrate gypsum sets quickly, and its rapid setting characteristic allows for the early and rapid solidification and shaping of foams. Furthermore, the hydration of hemihydrate gypsum itself provides strength and a dense structural system.

[0011] Through experiments, the inventors discovered that when sulfoaluminate cement, silicate cement, and hemihydrate gypsum are mixed in a specific mass ratio to prepare carbon dioxide foamed concrete, a synergistic hydration effect among the three components can be achieved, thereby significantly improving the mechanical properties of the carbon dioxide foamed concrete. The composite cementitious material in this invention features early strength and rapid hardening, enabling rapid curing and shaping of foam, especially for high-concentration carbon dioxide foam.

[0012] An appropriate amount of CO2 reacts with the hydration products of the cementitious system (mineralization reaction) to generate stable carbonates and silica gel, making the pore walls of foamed concrete denser, which is beneficial to improving the strength of foamed concrete and optimizing its performance.

[0013] The role of mineral powder is twofold: on the one hand, it can provide reactants; on the other hand, it is beneficial to improve the strength of foamed concrete.

[0014] Calcium stearate acts as a foam stabilizer.

[0015] Hydroxypropyl methylcellulose ether is used as a foam stabilizer.

[0016] In some embodiments, the ore powder is blast furnace slag powder, mainly including S95 grade and S105 grade.

[0017] Preferably, the composite gel-physical foaming synergistic carbon dioxide foam concrete is composed of the following components by mass:

[0018] 15-45 parts sulfoaluminate cement, 10-50 parts hemihydrate gypsum, 5-15 parts silicate cement, 2-20 parts mineral powder, 0.1-0.3 parts gypsum retarder, 0.2-0.4 parts retarder, 0.2-0.4 parts water-reducing agent, 0.2-0.6 parts calcium stearate, 0.1-0.3 parts hydroxypropyl methylcellulose ether, water-cement ratio 0.2-0.45, and 5-15 parts precast foam.

[0019] More preferably, the composite gel-physical foaming synergistic carbon dioxide foam concrete is composed of the following components by weight:

[0020] 15-30 parts sulfoaluminate cement, 10-40 parts hemihydrate gypsum, 5-10 parts silicate cement, 2-10 parts mineral powder, 0.1-0.3 parts gypsum retarder, 0.2-0.4 parts retarder, 0.2-0.4 parts water-reducing agent, 0.2-0.5 parts calcium stearate, 0.1-0.3 parts hydroxypropyl methylcellulose ether, water-cement ratio 0.2-0.4, and 5-15 parts precast foam.

[0021] In some embodiments, the pre-formed foam is prepared by mixing a foaming agent and water at a mass ratio of 1:20-40.

[0022] Preferably, the foaming agent is a rosin resin-based foaming agent, an ionic foaming agent, a protein-based foaming agent, or a composite foaming agent.

[0023] In some embodiments, the retarder is boric acid or tartaric acid.

[0024] The present invention uses a large amount of gypsum, which sets quickly in the early stage, so a targeted gypsum retarder is more effective; the addition of the retarder has a slowing effect on the setting of other components.

[0025] In some embodiments, the water-reducing agent is a polycarboxylate water-reducing agent or a naphthalene-based water-reducing agent.

[0026] Secondly, the present invention provides a preparation process for the composite gel-physical foaming synergistic carbon dioxide foam concrete, comprising the following steps:

[0027] Sulfoaluminate cement, hemihydrate gypsum, silicate cement, mineral powder, gypsum retarder, retarder, water-reducing agent, calcium stearate and hydroxypropyl methylcellulose ether are mixed evenly in proportion to obtain a compound material;

[0028] Pour water into the compound material according to the set water-cement ratio and stir to form a slurry;

[0029] After mixing the slurry and pre-made foam in a certain proportion, pour it into a mold, shape it, demold it, and cure it to obtain the final product.

[0030] In some embodiments, water is poured into the compound material and the mixture is stirred rapidly for 120-180 seconds.

[0031] In some embodiments, the molding time is 4-6 hours.

[0032] In some embodiments, the pre-formed foam is produced by mixing a foaming agent with water at a mass ratio of 1:20-40.

[0033] Preferably, the foaming gas of the pre-formed foam is a mixture of carbon dioxide and air, and the volume percentage of carbon dioxide in the foaming gas is 20%-70%; more preferably 30%-50%.

[0034] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0035] The solid waste-based CO2 foamed concrete of the present invention fully meets the requirements of lightweight, high strength and thermal insulation of foamed concrete.

[0036] The synergistic hydration effect of sulfoaluminate cement, silicate cement and hemihydrate gypsum significantly improves the mechanical properties and other parameters of carbon dioxide foamed concrete, which provides a foundation for lightweight and high-strength design.

[0037] Carbon dioxide has a positive effect on the system formed by sulfoaluminate cement, silicate cement and hemihydrate gypsum, and significantly reduces the apparent density while ensuring that the foamed concrete meets the strength requirements.

[0038] After curing, it can meet the construction requirements of prefabricated buildings. While reducing density, the strength can still meet the standard limits. The curing cycle is short and it can achieve rapid demolding. Attached Figure Description

[0039] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0040] Figure 1 This is a process flow diagram of an embodiment of the present invention. Detailed Implementation

[0041] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0042] The present invention will be further described below with reference to the embodiments.

[0043] Example 1

[0044] A composite gel-physical foaming synergistic carbon dioxide foam concrete, by weight, comprises the following components: 42 parts sulfoaluminate cement, 14 parts hemihydrate gypsum, 14 parts silicate cement, 30 parts mineral powder, 0.1 parts gypsum retarder, 0.2 parts retarder, 0.2 parts water-reducing agent, 0.6 parts calcium stearate, 0.2 parts hydroxypropyl methylcellulose ether, 45 parts water, 10 parts precast foam, and a carbon dioxide concentration of 50%.

[0045] The water-reducing agent is a polycarboxylate water-reducing agent, the foam stabilizer is calcium stearate, and the water used meets the requirements for concrete mixing water.

[0046] The preparation process of carbon dioxide foam concrete with synergistic effects of composite gel and physical foaming includes the following steps:

[0047] (1) Thoroughly premix and stir 42 parts of solid waste-based sulfoaluminate cement, 14 parts of hemihydrate gypsum, 14 parts of silicate cement and 30 parts of mineral powder for later use.

[0048] (2) Add 0.3 parts of retarder, 0.2 parts of water-reducing agent, 0.6 parts of calcium stearate, and 0.2 parts of hydroxypropyl methylcellulose ether to the raw materials prepared in step (1), stir and mix for 2 minutes to prepare a compound material for later use;

[0049] (3) Take 45 parts of tap water and pour it into the compound material prepared in step (2) all at once, and stir quickly for 180 seconds to form a slurry;

[0050] (4) At the same time, according to the ratio of protein foaming agent: water = 1:30, fresh pre-made foam is prepared by using carbon dioxide physical foaming agent. The foaming gas is a mixture of carbon dioxide and air. The volume percentage of carbon dioxide in the foaming gas is 50%.

[0051] (5) After mixing the pre-made foam prepared in step (4) with the slurry prepared in step (3), stir it to make it fully mixed, then pour the slurry into the mold, let it naturally form for 6 hours, demold it, and cure it under standard curing conditions to obtain lightweight high-strength carbon dioxide foam concrete material.

[0052] Comparative Example 1

[0053] Material composition: 36 parts desulfurized gypsum, 16 parts red mud, 22 parts aluminum ash, and 26 parts calcium carbide slag;

[0054] Preparation method: Air physical foaming, mixed with slurry to prepare foamed concrete.

[0055] Comparative Example 2

[0056] The difference from Example 1 is that hemihydrate gypsum is replaced with gypsum, while everything else is the same as in Example 1.

[0057] Comparative Example 3

[0058] The difference from Example 1 is that silicate cement is replaced with sulfoaluminate cement, while everything else is the same as in Example 1.

[0059] Comparative Example 4

[0060] The difference from Example 1 is that sulfoaluminate cement is replaced with silicate cement, while everything else is the same as in Example 1.

[0061] Comparative Example 5

[0062] The difference from Example 1 is that the carbon dioxide foaming is replaced with compressed air, while everything else is the same as Example 1.

[0063] Table 1. Performance of carbon dioxide foamed concrete prepared in Example 1 and Comparative Examples 1-5

[0064] <![CDATA[Dry density (kg / m 3 )]]> Compressive strength (MPa) Example 1 769.87 7.54 Comparative Example 1 752.38 4.56 Comparative Example 2 770.56 6.62 Comparative Example 3 762.83 6.55 Comparative Example 4 745.33 5.67 Comparative Example 5 750.29 4.96

[0065] Example 2

[0066] A composite gel-physical foaming synergistic carbon dioxide foam concrete, by weight, comprises the following components: 23 parts sulfoaluminate cement, 40 parts hemihydrate gypsum, 7 parts silicate cement, 30 parts mineral powder, 0.1 parts gypsum retarder, 0.2 parts retarder, 0.2 parts water-reducing agent, 0.6 parts calcium stearate, 0.2 parts hydroxypropyl methylcellulose ether, 30 parts water, 15 parts pre-formed foam, and a carbon dioxide concentration of 50%.

[0067] The water-reducing agent is a polycarboxylate water-reducing agent, the foam stabilizer is calcium stearate, and the water used meets the requirements for concrete mixing water.

[0068] The preparation process of the composite gel-physical foaming synergistic carbon dioxide foam concrete includes the following steps:

[0069] (1) Use 23 parts of solid waste-based sulfoaluminate cement, 40 parts of hemihydrate gypsum, 7 parts of silicate cement, and 30 parts of mineral powder to fully premix and stir for later use.

[0070] (2) Add 0.3 parts of retarder, 0.2 parts of water-reducing agent, 0.6 parts of calcium stearate and 0.2 parts of hydroxypropyl methylcellulose ether to the mixed raw materials prepared in step (1), stir and mix for 2 minutes to prepare a compound material for later use;

[0071] (3) Take 30 parts of tap water and pour it into the compound material prepared in step (2) all at once, and stir quickly for 120-180s to form a slurry;

[0072] (4) According to the ratio of protein foaming agent to water = 1:30, carbon dioxide is used for physical foaming to produce fresh pre-made foam. The foaming gas is a mixture of carbon dioxide and air, and the volume percentage of carbon dioxide in the foaming gas is 50%.

[0073] (5) After mixing the pre-made foam prepared in step (4) with the slurry prepared in step (3), stir it to make it fully mixed, then pour it into the mold, let it naturally form for 5 hours, demold it, and cure it under standard curing conditions to obtain lightweight high-strength carbon dioxide foam concrete material.

[0074] Comparative Example 6

[0075] The difference from Example 2 is that hemihydrate gypsum is replaced with gypsum, while everything else is the same as in Example 2.

[0076] Comparative Example 7

[0077] The difference from Example 2 is that silicate cement is replaced with sulfoaluminate cement, while everything else is the same as in Example 2.

[0078] Comparative Example 8

[0079] The difference from Example 2 is that sulfoaluminate cement is replaced with silicate cement, while everything else is the same as in Example 2.

[0080] Comparative Example 9

[0081] The difference from Example 2 is that the carbon dioxide foaming is replaced with compressed air, while everything else is the same as Example 2.

[0082] Table 2. Performance of carbon dioxide foamed concrete prepared in Example 2 and Comparative Examples 6-9

[0083] <![CDATA[Dry density (kg / m 3 )]]> Compressive strength (MPa) Example 2 711.58 7.96 Comparative Example 6 751.32 6.88 Comparative Example 7 737.15 7.01 Comparative Example 8 746.79 6.83 Comparative Example 9 706.43 4.62

[0084] Example 3

[0085] A composite gel-physical foaming synergistic carbon dioxide foam concrete, by weight, comprises the following components: 18 parts sulfoaluminate cement, 46 parts hemihydrate gypsum, 6 parts silicate cement, 30 parts mineral powder, 0.1 parts gypsum retarder, 0.2 parts retarder, 0.2 parts water-reducing agent, 0.6 parts calcium stearate, 0.2 parts hydroxypropyl methylcellulose ether, 20 parts water, 7 parts precast foam, and 50% carbon dioxide concentration.

[0086] The water-reducing agent is a polycarboxylate water-reducing agent, the foam stabilizer is calcium stearate, and the water used meets the requirements for concrete mixing water.

[0087] The process for preparing carbon dioxide foam concrete using a composite gel-physical foaming synergy includes the following steps:

[0088] (1) Thoroughly premix and stir 18 parts of solid waste-based sulfoaluminate cement, 46 parts of hemihydrate gypsum, 6 parts of silicate cement and 30 parts of mineral powder for later use.

[0089] (2) Add 0.3 parts of retarder, 0.2 parts of water-reducing agent, 0.6 parts of calcium stearate and 0.2 parts of hydroxypropyl methylcellulose ether to the mixed raw materials prepared in step (1), stir and mix for 2 minutes to prepare a compound material for later use;

[0090] (3) Take 20 parts of tap water and pour it into the compound material prepared in step (2) all at once, and stir quickly for 120 seconds to form a slurry;

[0091] (4) At the same time, according to the ratio of protein foaming agent to water = 1:30, carbon dioxide is used for physical foaming to produce fresh pre-made foam. The foaming gas is a mixture of carbon dioxide and air, and the volume percentage of carbon dioxide in the foaming gas is 50%.

[0092] (5) After mixing the pre-made foam prepared in step (4) with the slurry prepared in step (3), stir it to make it fully mixed, then pour it into the mold, let it naturally form for 4 hours, demold it, and cure it under standard curing conditions to obtain lightweight high-strength carbon dioxide foam concrete material.

[0093] Table 3. Performance of the carbon dioxide foamed concrete prepared in Example 3

[0094]

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite gel-physical foaming synergistic carbon dioxide foam concrete, characterized in that: By weight, it consists of the following components: Sulfoaluminate cement 15-45 parts, hemihydrate gypsum 10-50 parts, silicate cement 5-15 parts, mineral powder 1-30 parts, gypsum retarder 0-0.3 parts, retarder 0.2-0.4 parts, water-reducing agent 0.2-0.4 parts, calcium stearate 0.2-0.6 parts, hydroxypropyl methylcellulose ether 0.1-0.3 parts, water-cement ratio 0.2-0.45, precast foam 5-15 parts; The foaming gas of the pre-made foam is a mixture of carbon dioxide and air.

2. The composite gel-physical foaming synergistic carbon dioxide foam concrete according to claim 1, characterized in that: The mineral powder is blast furnace slag powder.

3. The composite gel-physical foaming synergistic carbon dioxide foam concrete according to claim 1, characterized in that: By weight, it consists of the following components: 15-45 parts sulfoaluminate cement, 10-50 parts hemihydrate gypsum, 5-15 parts silicate cement, 2-20 parts mineral powder, 0.1-0.3 parts gypsum retarder, 0.2-0.4 parts retarder, 0.2-0.4 parts water-reducing agent, 0.2-0.6 parts calcium stearate, 0.1-0.3 parts hydroxypropyl methylcellulose ether, water-cement ratio 0.2-0.45, and 5-15 parts precast foam.

4. The composite gel-physical foaming synergistic carbon dioxide foam concrete according to claim 3, characterized in that: By weight, it consists of the following components: 15-30 parts sulfoaluminate cement, 10-40 parts hemihydrate gypsum, 5-10 parts silicate cement, 2-10 parts mineral powder, 0.1-0.3 parts gypsum retarder, 0.2-0.4 parts retarder, 0.2-0.4 parts water-reducing agent, 0.2-0.5 parts calcium stearate, 0.1-0.3 parts hydroxypropyl methylcellulose ether, water-cement ratio 0.2-0.4, and 5-15 parts precast foam.

5. The carbon dioxide foamed concrete with composite gel-physical foaming synergy according to any one of claims 1-4, characterized in that: The pre-made foam is prepared by mixing foaming agent and water at a mass ratio of 1:20-40.

6. The composite gel-physical foaming synergistic carbon dioxide foam concrete according to claim 5, characterized in that: The foaming agent is a rosin resin-based foaming agent, an ionic foaming agent, a protein-based foaming agent, or a composite foaming agent.

7. The composite gel-physical foaming synergistic carbon dioxide foam concrete according to claim 1, characterized in that: The retarder is boric acid or tartaric acid.

8. The composite gel-physical foaming synergistic carbon dioxide foam concrete according to claim 1, characterized in that: The water-reducing agent is a polycarboxylate water-reducing agent or a naphthalene-based water-reducing agent.

9. The preparation process of the composite gel-physical foaming synergistic carbon dioxide foam concrete according to any one of claims 1-8, characterized in that: Includes the following steps: Sulfoaluminate cement, hemihydrate gypsum, silicate cement, mineral powder, gypsum retarder, retarder, water-reducing agent, calcium stearate and hydroxypropyl methylcellulose ether are mixed evenly in proportion to obtain a compound material; Pour water into the compound material according to the set water-cement ratio and stir to form a slurry; After mixing the slurry and pre-made foam in a certain proportion, pour it into a mold, shape it, demold it, and cure it to obtain the final product.

10. The preparation process of the composite gel-physical foaming synergistic carbon dioxide foam concrete according to claim 9, characterized in that: Pour water into the compound material and stir quickly for 120-180 seconds.

11. The preparation process of the composite gel-physical foaming synergistic carbon dioxide foam concrete according to claim 9, characterized in that: The molding time is 4-6 hours.

12. The preparation process of the composite gel-physical foaming synergistic carbon dioxide foam concrete according to claim 9, characterized in that: The pre-made foam is produced by mixing a foaming agent and water at a mass ratio of 1:20-40.

13. The preparation process of the composite gel-physical foaming synergistic carbon dioxide foam concrete according to claim 9, characterized in that: The foaming gas for pre-formed foam is a mixture of carbon dioxide and air, with the volume percentage of carbon dioxide in the foaming gas being 20%-70%.

14. The preparation process of the composite gel-physical foaming synergistic carbon dioxide foam concrete according to claim 13, characterized in that: The volume percentage of carbon dioxide in the foaming gas is 30%-50%.

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