Low-shrinkage lightweight high-strength alkali-activated foam concrete and preparation method and application thereof

Abstract

The application discloses low-shrinkage light-weight high-strength alkali-activated foam concrete and a preparation method and application thereof. The raw material composition of the foam concrete comprises 30-80 parts by weight of slag powder, 40-120 parts by weight of mineral admixture, 2-15 parts by weight of porous filler, 5-20 parts by weight of sodium-potassium water glass, 0.5-10 parts by weight of foaming agent and 0.5-5 parts by weight of anti-shrinkage agent. The anti-shrinkage agent is prepared by the following method: placing water-absorbing resin in a saturated shrinkage reducing agent solution, keeping under heating conditions, making the water-absorbing resin reach a saturated water state, and then separating the water-absorbing resin and draining the liquid to obtain the anti-shrinkage agent. The application not only reduces the self-shrinkage degree of the alkali-activated foam concrete, overcomes the shrinkage and cracking problem of the foam concrete during service, but also increases the compressive strength of the alkali-activated foam concrete.

Description

Technical Field

[0001] This invention relates to the field of foamed concrete technology, specifically to a low-shrinkage, lightweight, high-strength alkali-activated foamed concrete, its preparation method, and its application. Background Technology

[0002] Alkali-activated foamed concrete, a novel type of cementitious material, possesses advantages such as rapid hardening, good thermal insulation, high strength, and environmental friendliness. These advantages stem from the high specific surface area and reactivity of its amorphous cementitious material, enabling rapid setting and strength development. However, this rapid curing reaction also leads to the rapid consumption of free water, resulting in a series of challenges. With the depletion of free water, the relative humidity inside the concrete decreases, and various stresses (such as capillary pressure, interlayer water migration pressure, and separation pressure) dominated by changes in internal humidity accumulate, leading to poor volume stability, easy cracking, and decreased strength in alkali-activated foamed concrete. The porous nature of foamed concrete also limits its performance in practical applications. Current solutions mainly involve adding internal curing materials and fillers to alkali-activated foamed concrete. However, the curing amount of internal curing materials is limited, and their shrinkage reduction effect on alkali-activated materials is not significant. While fillers can act as a skeleton to inhibit shrinkage, their low cementitious activity and high roughness degrade the interface between the foam and the alkali-activated cementitious material, affecting the density and compressive strength of alkali-activated foamed concrete. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a low-shrinkage, lightweight, high-strength alkali-activated foamed concrete, its preparation method, and its applications. This not only reduces the degree of auto-shrinkage in alkali-activated foamed concrete, overcoming the problem of shrinkage cracking during service, but also increases the compressive strength of the alkali-activated foamed concrete. Specifically, this invention discloses the following technical solution.

[0004] First, this invention discloses a low-shrinkage, lightweight, high-strength alkali-activated foamed concrete, the raw material composition of which includes: 30-80 parts by weight of slag powder, 40-120 parts by weight of mineral admixtures, 2-15 parts by weight of porous filler, 5-20 parts by weight of sodium-potassium water glass, 0.5-10 parts by weight of foaming agent, and 0.5-5 parts by weight of anti-shrinkage agent. The anti-shrinkage agent is prepared by the following method: water-absorbing resin is placed in a saturated anti-shrinkage agent solution and kept at a heated temperature until the water-absorbing resin reaches a saturated state. Then, the water-absorbing resin is separated and the liquid is drained to obtain the anti-shrinkage agent.

[0005] Further, the superabsorbent resin includes at least one polymer or copolymer of acrylic acid, acrylamide, carboxymethyl cellulose, etc. Preferably, it is an acrylamide resin, whose hydrophilic groups (-NH2) are unaffected by calcium ions, thus better preventing complexation with calcium ions in the foamed concrete. This is because calcium ions can form coordination bonds with the carboxyl and hydroxyl groups in the superabsorbent resin, altering the internal three-dimensional network structure of the resin, causing the three-dimensional network structure to shrink and collapse prematurely, leading to the premature release of the saturated shrinkage-reducing agent solution. Optionally, the heating temperature is 50~85℃, and the holding time is 0.5~1h.

[0006] Further, the saturated shrinkage-reducing agent solution is a saturated liquid formed by dissolving any one of polyether, polyol, etc., in water. Optionally, the polyether includes a polymer or copolymer of at least one of ethylene ether, alkyl ether oxide, vinyl methyl ether, etc. The polyol includes a polymer or copolymer of at least one of ethylene glycol, alkylene glycol, olefin glycol, etc.

[0007] Furthermore, the mineral admixture includes, but is not limited to, at least one of: fly ash, kaolin, metakaolin, etc. Optionally, the fineness range of the mineral admixture is 40-200 mesh.

[0008] Furthermore, the porous filler includes, but is not limited to, at least one of: ceramsite, expanded perlite, expanded vermiculite, etc. Optionally, the particle size of the porous filler is 30~200 μm.

[0009] Further, the sodium-potassium silicate water glass is prepared by mixing liquid sodium silicate or liquid potassium silicate, potassium hydroxide or sodium hydroxide, and water. Optionally, the ratio of the liquid sodium silicate or liquid potassium silicate, potassium hydroxide or sodium hydroxide, and water is 20-80 parts by weight: 10-35 parts by weight: 10-25 parts by weight. Optionally, the mass fraction of the liquid sodium silicate or liquid potassium silicate is 30-40%. It should be understood that the combination of liquid sodium silicate and potassium hydroxide, and the combination of liquid potassium silicate and sodium hydroxide, provides sodium and potassium elements for the preparation of the sodium-potassium silicate water glass.

[0010] Further, the foaming agent is a compound of component A, component B, silicone polyether emulsion, and water. Component A includes at least one of sodium fatty alcohol polyoxyethylene ether sulfate, sodium dodecyl sulfate, and sodium α-alkenyl sulfonate; component B includes at least one of starch ether and cellulose ether. Optionally, the ratio of component A, component B, silicone polyether emulsion, and water is 1-5 parts by weight: 0.02-0.05 parts by weight: 0.2-1 parts by weight: 50-85 parts by weight. Using this compounded foaming agent helps solve the stability problem of foam in an alkali-activated system. Its working principle is that component A has stronger compatibility with the alkali-activated system, thus significantly improving the foaming agent's adaptability to alkaline environments. The silicone polyether emulsion promotes denser foam; component B effectively increases foam toughness, making the foam structure more stable. The synergistic effect between the above components allows the resulting foam structure to exist more stably in alkali-activated foamed concrete.

[0011] Secondly, the present invention discloses a method for preparing low-shrinkage, lightweight, high-strength alkali-activated foamed concrete, comprising the following steps:

[0012] (1) Mix the slag powder, mineral admixture and porous filler evenly to form a dry powder for later use.

[0013] (2) Add the dry powder to sodium potassium water glass and stir evenly, then add the anti-shrinkage agent, stir evenly to obtain a slurry, and set aside.

[0014] (3) After foaming the foaming agent, mix it evenly with the slurry to obtain alkali-activated foamed concrete.

[0015] Further, in step (2), the dry powder is added to sodium potassium water glass and stirred for 1-5 minutes. After adding the anti-shrinkage agent, stirring is continued for 1-3 minutes to obtain the slurry.

[0016] Further, in step (3), the foaming method is to stir the foaming agent at a speed of 300~1000 rpm for 1~2 minutes.

[0017] Further, in step (3), the foaming agent after foaming is mixed with the slurry and stirred for 1 to 3 minutes.

[0018] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0019] (1) The alkali-activated foamed concrete of the present invention uses a novel anti-shrinkage agent, which is based on a water-absorbing resin and utilizes its fully expanded network segments to load the shrinkage-reducing agent. After this anti-shrinkage agent enters the alkali-activated foamed concrete, the water-absorbing resin matrix utilizes its slow-release effect to reduce the contact between the shrinkage-reducing agent and the concrete in the early stage of hydration, thereby reducing the adverse effects of the shrinkage-reducing agent on the hydration of the cementitious materials in the concrete during this stage. This is because if the shrinkage-reducing agent enters the cementitious materials too early, it will coat its surface, affecting the contact between the cementitious materials and water, and reducing the dissolution of hydration-related ions, thereby causing insufficient hydration of the cementitious materials, which in turn leads to the deterioration of the mechanical strength of the foamed concrete. Meanwhile, as water is continuously consumed during the hydration process, the internal and external pressure difference of the anti-shrinkage agent increases, providing impetus for the release of the shrinkage-reducing agent in the water-absorbing resin matrix. This effectively controls the release of the shrinkage-reducing agent in the later stage of cementitious material hydration. At the same time, after the shrinkage-reducing agent enters the pore solution environment in the later stage of hydration, it can reduce the surface tension of the solution in the capillary pores, thereby reducing the capillary pressure. This not only effectively prevents the self-shrinkage cracking of concrete caused by the reduction of water, but also effectively reduces the adverse effects on the hydration of cementitious materials. The present invention utilizes the synergistic effect of the anti-shrinkage agent to obtain alkali-activated foamed concrete that has both high strength and effective resistance to shrinkage.

[0020] (2) In the foamed concrete of the present invention, by introducing the porous filler, the skeletal effect not only reduces the shrinkage of the foamed concrete material, but also significantly improves its strength. This is because: these porous fillers can provide additional internal support points, which can effectively disperse stress and limit the volume reduction of the foamed concrete material during the curing process. At the same time, the porous structure helps to reduce stress concentration inside the cement-based material and reduce the formation of cracks caused by drying shrinkage. Attached Figure Description

[0021] 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.

[0022] Figure 1 The following diagram shows the compressive strength test results of the alkali-activated foamed concrete specimen from Example 1.

[0023] Figure 2 The following are shrinkage test diagrams of alkali-activated foamed concrete specimens from Examples 1-3. Detailed Implementation

[0024] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0025] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. All reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions.

[0026] Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the method of this invention. The technical solution of this invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0027] Example 1

[0028] A method for preparing low-shrinkage, lightweight, high-strength alkali-activated foamed concrete includes the following steps:

[0029] (1) Preparation of anti-shrinkage agent: Fatty acid methyl ester ethoxylate (FMEE) is added to water to form a saturated solution, which is the saturated anti-shrinkage agent solution. Then, water-absorbing resin (polyacrylamide resin) is placed in the saturated anti-shrinkage agent solution, heated to 70°C and kept at that temperature for 45 minutes. After separating the water-absorbing resin, the liquid is drained to obtain the anti-shrinkage agent for later use.

[0030] (2) Preparation of sodium-potassium water glass: Mix liquid sodium silicate (mass fraction 34%), potassium hydroxide and water in a ratio of 50 parts by weight: 27 parts by weight: 20 parts by weight and stir evenly to obtain sodium-potassium water glass for later use.

[0031] (3) Preparation of foaming agent: Sodium fatty alcohol polyoxyethylene ether sulfate, hydroxypropyl starch ether, silicone resin polyether emulsion (Fumais FM-550) and water are mixed in a ratio of 3.5 parts by weight: 0.03 parts by weight: 0.6 parts by weight: 70 parts by weight and stirred evenly to obtain the foaming agent for later use.

[0032] (4) Take the following raw materials: 50 parts by weight of slag powder, 85 parts by weight of mineral admixture, 10 parts by weight of porous filler, 14 parts by weight of the sodium-potassium water glass prepared in this embodiment, 7 parts by weight of the foaming agent prepared in this embodiment, and 3 parts by weight of the anti-shrinkage agent prepared in this embodiment. Wherein: the fineness of the slag powder is 200 mesh, the fineness of the mineral admixture is fly ash with a fineness of 200 mesh, and the porous filler is expanded perlite powder with a particle size distribution between 30 and 200 μm.

[0033] (5) Mix the slag powder, mineral admixture and porous filler and stir evenly to obtain dry powder for later use.

[0034] (6) Add the dry powder to sodium potassium water glass and stir for 3 minutes, then add the anti-shrinkage agent and continue stirring for 2 minutes to obtain a slurry for later use.

[0035] (7) Add the foaming agent to the foaming machine and stir rapidly at 800 rpm for 2 minutes to form foam. Then add the slurry and continue stirring at 100 rpm for 2 minutes to obtain alkali-activated foamed concrete.

[0036] The autogenous shrinkage properties of the alkali-activated foamed concrete prepared in this embodiment were tested according to ASTM C1698-09 (2014), and the compressive strength of the alkali-activated foamed concrete was tested according to JG / T 266-2011. The results are shown in the table below:

[0037] .

[0038] Example 2

[0039] A method for preparing low-shrinkage, lightweight, high-strength alkali-activated foamed concrete includes the following steps:

[0040] (1) Preparation of anti-shrinkage agent: Polyoxyethylene ether is added to water to form a saturated solution, which is the saturated anti-shrinkage agent solution. Then, water-absorbing resin (polyacrylamide resin) is placed in the saturated anti-shrinkage agent solution, and then heated to 85°C and kept at that temperature for 30 minutes. After separating the water-absorbing resin, the liquid is drained to obtain the anti-shrinkage agent for later use.

[0041] (2) Preparation of sodium-potassium water glass: Mix liquid sodium silicate (30% by mass), potassium hydroxide and water in a ratio of 80 parts by weight: 35 parts by weight: 25 parts by weight and stir until homogeneous to obtain sodium-potassium water glass for later use.

[0042] (3) Preparation of foaming agent: Sodium dodecyl sulfate, hydroxypropyl starch ether, silicone polyether emulsion (Fumais FM-550) and water are mixed in a ratio of 1 part by weight: 0.02 parts by weight: 0.2 parts by weight: 50 parts by weight and stirred evenly to obtain the foaming agent for later use.

[0043] (4) Take the following raw materials: 30 parts by weight of slag powder, 40 parts by weight of mineral admixture, 2 parts by weight of porous filler, 5 parts by weight of the sodium-potassium water glass prepared in this embodiment, 0.5 parts by weight of the foaming agent prepared in this embodiment, and 0.5 parts by weight of the anti-shrinkage agent prepared in this embodiment. Wherein: the fineness of the slag powder is 200 mesh, the fineness of the mineral admixture is kaolin with a fineness of 100 mesh, and the porous filler is ceramsite powder with a particle size distribution between 30 and 200 μm.

[0044] (5) Mix the slag powder, mineral admixture and porous filler and stir evenly to obtain dry powder for later use.

[0045] (6) Add the dry powder to sodium potassium water glass and stir for 5 minutes, then add the anti-shrinkage agent and continue stirring for 3 minutes to obtain a slurry for later use.

[0046] (7) Add the foaming agent to the foaming machine and stir rapidly at 300 rpm for 2 minutes to form foam. Then add the slurry and continue stirring at 50 rpm for 3 minutes to obtain alkali-activated foamed concrete.

[0047] The autogenous shrinkage properties of the alkali-activated foamed concrete prepared in this embodiment were tested according to ASTM C1698-09 (2014), and the compressive strength of the alkali-activated foamed concrete was tested according to JG / T 266-2011. The results are shown in the table below:

[0048] .

[0049] Example 3

[0050] A method for preparing low-shrinkage, lightweight, high-strength alkali-activated foamed concrete includes the following steps:

[0051] (1) Preparation of anti-shrinkage agent: Polyethylene glycol (PEG600) is added to water to form a saturated solution, which is the saturated anti-shrinkage agent solution. Then, water-absorbing resin (acrylamide resin) is placed in the saturated anti-shrinkage agent solution, heated to 50°C and kept at that temperature for 60 minutes. After separating the water-absorbing resin, the liquid is drained to obtain the anti-shrinkage agent for later use.

[0052] (2) Preparation of sodium potassium water glass: Mix liquid potassium silicate (40% by mass), sodium hydroxide and water in a ratio of 20 parts by weight: 10 parts by weight: 10 parts by weight and stir evenly to obtain sodium potassium water glass for later use.

[0053] (3) Preparation of foaming agent: Sodium α-alkenylsulfonate, hydroxypropyl methylcellulose ether, silicone polyether emulsion (Fumais FM-550) and water are mixed in a ratio of 5 parts by weight: 0.05 parts by weight: 1 part by weight: 85 parts by weight and stirred evenly to obtain the foaming agent for later use.

[0054] (4) Take the following raw materials: 80 parts by weight of slag powder, 120 parts by weight of mineral admixture, 15 parts by weight of porous filler, 20 parts by weight of the sodium potassium water glass prepared in this embodiment, 10 parts by weight of the foaming agent prepared in this embodiment, and 5 parts by weight of the anti-shrinkage agent prepared in this embodiment. Wherein: the fineness of the slag powder is 300 mesh, the mineral admixture is composed of 60 parts by weight of fly ash with a fineness of 40 mesh and 60 parts by weight of metakaolin, and the porous filler is expanded vermiculite powder with a particle size distribution between 30 and 200 μm.

[0055] (5) Mix the slag powder, mineral admixture and porous filler and stir evenly to obtain dry powder for later use.

[0056] (6) Add the dry powder to sodium potassium water glass and stir for 1 minute, then add the anti-shrinkage agent and continue stirring for 1 minute to obtain a slurry for later use.

[0057] (7) Add the foaming agent to the foaming machine and stir rapidly at 1000 rpm for 1 min to form foam. Then add the slurry and continue stirring at 120 rpm for 1 min to obtain alkali-activated foamed concrete.

[0058] The autogenous shrinkage properties of the alkali-activated foamed concrete prepared in this embodiment were tested according to ASTM C1698-09 (2014), and the compressive strength of the alkali-activated foamed concrete was tested according to JG / T 266-2011. The results are shown in the table below:

[0059] .

[0060] Example 4

[0061] A method for preparing alkali-activated foamed concrete includes the following steps:

[0062] (1) Preparation of sodium-potassium water glass: Mix liquid sodium silicate (mass fraction 34%), potassium hydroxide and water in a ratio of 50 parts by weight: 27 parts by weight: 20 parts by weight and stir until homogeneous to obtain sodium-potassium water glass for later use.

[0063] (2) Preparation of foaming agent: Sodium fatty alcohol polyoxyethylene ether sulfate, hydroxypropyl starch ether, silicone resin polyether emulsion (Fumais FM-550) and water are mixed in a ratio of 3.5 parts by weight: 0.03 parts by weight: 0.6 parts by weight: 70 parts by weight and stirred evenly to obtain the foaming agent for later use.

[0064] (3) Take the following raw materials: 50 parts by weight of slag powder, 85 parts by weight of mineral admixture, 10 parts by weight of porous filler, 14 parts by weight of the sodium-potassium water glass prepared in this embodiment, 7 parts by weight of the foaming agent prepared in this embodiment, and 3 parts by weight of acrylamide resin. Wherein: the fineness of the slag powder is 200 mesh, the fineness of the mineral admixture is fly ash with a fineness of 200 mesh, and the porous filler is expanded perlite powder with a particle size distribution between 30 and 200 μm.

[0065] (4) Mix the slag powder, mineral admixture and porous filler and stir evenly to obtain dry powder for later use.

[0066] (5) Add the dry powder to sodium potassium water glass and stir for 3 minutes, then add the anti-shrinkage agent and continue stirring for 2 minutes to obtain a slurry for later use.

[0067] (6) Add the foaming agent to the foaming machine and stir rapidly at 800 rpm for 2 minutes to form foam. Then add the slurry and continue stirring at 100 rpm for 2 minutes to obtain alkali-activated foamed concrete.

[0068] The autogenous shrinkage properties of the alkali-activated foamed concrete prepared in this embodiment were tested according to ASTM C1698-09 (2014), and the compressive strength of the alkali-activated foamed concrete was tested according to JG / T 266-2011. The results are shown in the table below:

[0069] .

[0070] Example 5

[0071] A method for preparing alkali-activated foamed concrete includes the following steps:

[0072] (1) Preparation of sodium-potassium water glass: Mix liquid sodium silicate (30% by mass), potassium hydroxide and water in a ratio of 80 parts by weight: 35 parts by weight: 25 parts by weight and stir until homogeneous to obtain sodium-potassium water glass for later use.

[0073] (2) Preparation of foaming agent: Sodium dodecyl sulfate, hydroxypropyl starch ether, silicone polyether emulsion (Fumais FM-550) and water are mixed in a ratio of 1 part by weight: 0.02 parts by weight: 0.2 parts by weight: 50 parts by weight and stirred evenly to obtain the foaming agent for later use.

[0074] (3) Take the following raw materials: 30 parts by weight of slag powder, 40 parts by weight of mineral admixture, 2 parts by weight of porous filler, 5 parts by weight of the sodium potassium water glass prepared in this embodiment, 0.5 parts by weight of the foaming agent prepared in this embodiment, 0.3 parts by weight of polyoxyethylene ether, and 0.5 parts by weight of acrylamide resin. Wherein: the fineness of the slag powder is 300 mesh, the mineral admixture is composed of 60 parts by weight of fly ash with a fineness of 40 mesh and 60 parts by weight of metakaolin, and the porous filler is ceramsite powder with a particle size distribution between 30 and 200 μm.

[0075] (4) Mix the slag powder, mineral admixture and porous filler and stir evenly to obtain dry powder for later use.

[0076] (5) Add the dry powder to sodium potassium water glass and stir for 5 minutes. Then add the polyoxyethylene ether and acrylamide resin and continue stirring for 3 minutes to obtain a slurry for later use.

[0077] (6) Add the foaming agent to the foaming machine and stir rapidly at 300 rpm for 2 minutes to form foam. Then add the slurry and continue stirring at 50 rpm for 3 minutes to obtain alkali-activated foamed concrete.

[0078] The autogenous shrinkage properties of the alkali-activated foamed concrete prepared in this embodiment were tested according to ASTM C1698-09 (2014), and the compressive strength of the alkali-activated foamed concrete was tested according to JG / T 266-2011. The results are shown in the table below:

[0079] .

[0080] Example 6

[0081] A method for preparing alkali-activated foamed concrete includes the following steps:

[0082] (1) Preparation of anti-shrinkage agent: Fatty acid methyl ester ethoxylate (FMEE) is added to water to form a saturated solution, which is used as an anti-shrinkage agent.

[0083] (2) Preparation of sodium-potassium water glass: Mix liquid sodium silicate (mass fraction 34%), potassium hydroxide and water in a ratio of 50 parts by weight: 27 parts by weight: 20 parts by weight and stir evenly to obtain sodium-potassium water glass for later use.

[0084] (3) Preparation of foaming agent: Sodium fatty alcohol polyoxyethylene ether sulfate, hydroxypropyl starch ether, silicone resin polyether emulsion (Fumais FM-550) and water are mixed in a ratio of 3.5 parts by weight: 0.03 parts by weight: 0.6 parts by weight: 70 parts by weight and stirred evenly to obtain the foaming agent for later use.

[0085] (4) Take the following raw materials: 50 parts by weight of slag powder, 85 parts by weight of mineral admixture, 10 parts by weight of porous filler, 14 parts by weight of the sodium-potassium water glass prepared in this embodiment, 7 parts by weight of the foaming agent prepared in this embodiment, and 3 parts by weight of the anti-shrinkage agent prepared in this embodiment. Wherein: the fineness of the slag powder is 200 mesh, the fineness of the mineral admixture is fly ash with a fineness of 200 mesh, and the porous filler is expanded perlite powder with a particle size distribution between 30 and 200 μm.

[0086] (5) Mix the slag powder, mineral admixture and porous filler and stir evenly to obtain dry powder for later use.

[0087] (6) Add the dry powder to sodium potassium water glass and stir for 3 minutes, then add the anti-shrinkage agent and continue stirring for 2 minutes to obtain a slurry for later use.

[0088] (7) Add the foaming agent to the foaming machine and stir rapidly at 800 rpm for 2 minutes to form foam. Then add the slurry and continue stirring at 100 rpm for 2 minutes to obtain alkali-activated foamed concrete.

[0089] The autogenous shrinkage properties of the alkali-activated foamed concrete prepared in this embodiment were tested according to ASTM C1698-09 (2014), and the compressive strength of the alkali-activated foamed concrete was tested according to JG / T 266-2011. The results are shown in the table below:

[0090] .

[0091] Example 7

[0092] A method for preparing alkali-activated foamed concrete includes the following steps:

[0093] (1) Preparation of anti-shrinkage agent: Polyethylene glycol (PEG600) is added to water to form a saturated solution, which is the saturated anti-shrinkage agent solution. Then, water-absorbing resin (acrylamide resin) is placed in the saturated anti-shrinkage agent solution, heated to 50°C and kept at that temperature for 60 minutes. After separating the water-absorbing resin, the liquid is drained to obtain the anti-shrinkage agent for later use.

[0094] (2) Preparation of sodium potassium water glass: Mix liquid potassium silicate (40% by mass), sodium hydroxide and water in a ratio of 20 parts by weight: 10 parts by weight: 10 parts by weight and stir evenly to obtain sodium potassium water glass for later use.

[0095] (3) Preparation of foaming agent: Sodium α-alkenylsulfonate, hydroxypropyl methylcellulose ether, silicone polyether emulsion (Fumais FM-550) and water are mixed in a ratio of 5 parts by weight: 0.05 parts by weight: 1 part by weight: 85 parts by weight and stirred evenly to obtain the foaming agent for later use.

[0096] (4) Take the following raw materials: 80 parts by weight of slag powder, 120 parts by weight of mineral admixture, 15 parts by weight of porous filler, 20 parts by weight of the sodium potassium water glass prepared in this embodiment, 10 parts by weight of the foaming agent prepared in this embodiment, and 5 parts by weight of the anti-shrinkage agent prepared in this embodiment. Wherein: the fineness of the slag powder is 300 mesh, the mineral admixture is composed of 60 parts by weight of fly ash with a fineness of 40 mesh and 60 parts by weight of metakaolin, and the porous filler is expanded vermiculite powder with a particle size distribution between 30 and 200 μm.

[0097] (5) Mix the slag powder, mineral admixture and porous filler and stir evenly to obtain dry powder for later use.

[0098] (6) Add the dry powder to sodium potassium water glass and stir for 1 minute, then add the anti-shrinkage agent and continue stirring for 1 minute to obtain a slurry for later use.

[0099] (7) Add the foaming agent to the foaming machine and stir rapidly at 1000 rpm for 1 min to form foam. Then add the slurry and continue stirring at 120 rpm for 1 min to obtain alkali-activated foamed concrete.

[0100] The autogenous shrinkage properties of the alkali-activated foamed concrete prepared in this embodiment were tested according to ASTM C1698-09 (2014), and the compressive strength of the alkali-activated foamed concrete was tested according to JG / T 266-2011. The results are shown in the table below:

[0101] .

[0102] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-shrinkage, lightweight, high-strength alkali-activated foamed concrete, characterized in that, The raw material composition of the foamed concrete includes: 30-80 parts by weight of slag powder, 40-120 parts by weight of mineral admixtures, 2-15 parts by weight of porous filler, 5-20 parts by weight of sodium potassium water glass, 0.5-10 parts by weight of foaming agent, and 0.5-5 parts by weight of anti-shrinkage agent; wherein, the anti-shrinkage agent is prepared by the following method: The water-absorbing resin is placed in a saturated shrinkage-reducing agent solution and kept at a temperature under heating conditions until the water-absorbing resin reaches a saturated state. Then, the water-absorbing resin is separated and the liquid is drained to obtain the anti-shrinkage agent. The water-absorbing resin includes a polymer or copolymer of at least one of acrylic acid, acrylamide, and carboxymethyl cellulose. The saturated shrinkage-reducing agent solution is a saturated liquid formed by dissolving any one of polyether and polyol in water. The foaming agent is compounded from component A, component B, silicone polyether emulsion, and water. Component A includes at least one of sodium fatty alcohol polyoxyethylene ether sulfate, sodium dodecyl sulfate, and sodium α-alkenyl sulfonate, and component B includes at least one of starch ether and cellulose ether.

2. The low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 1, characterized in that, The water-absorbing resin is acrylamide resin.

3. The low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 1, characterized in that, The heating temperature is 50~85℃, and the holding time is 0.5~1h.

4. The low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 1, characterized in that, The polyether includes a polymer or copolymer of at least one of oxyethylene ether, alkyl ether oxide, and vinyl methyl ether.

5. The low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 1, characterized in that, The polyol includes polymers or copolymers of at least one of ethylene glycol, alkylene glycol, and olefinic glycol.

6. The low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 1, characterized in that, The mineral admixture includes at least one of fly ash, kaolin, and metakaolin.

7. The low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 1, characterized in that, The fineness range of the mineral admixture is 40~200 mesh.

8. The low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 1, characterized in that, The porous filler includes at least one of the following: ceramsite, expanded perlite, and expanded vermiculite.

9. The low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 1, characterized in that, The porous filler has a particle size of 30~200μm.

10. The low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 1, characterized in that, The sodium-potassium water glass is made by mixing liquid sodium silicate or liquid potassium silicate, potassium hydroxide or sodium hydroxide, and water.

11. The low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 10, characterized in that, The ratio of liquid sodium silicate or liquid potassium silicate, potassium hydroxide or sodium hydroxide, and water is 20-80 parts by weight: 10-35 parts by weight: 10-25 parts by weight.

12. The low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 10, characterized in that, The mass fraction of the liquid sodium silicate or liquid potassium silicate is 30-40%.

13. The low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to any one of claims 1-12, characterized in that, The ratio of component A, component B, silicone polyether emulsion, and water is 1~5 parts by weight: 0.02~0.05 parts by weight: 0.2~1 parts by weight: 50~85 parts by weight.

14. The method for preparing low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to any one of claims 1-13, characterized in that, Includes the following steps: (1) Mix the slag powder, mineral admixture, and porous filler evenly to form a dry powder for later use; (2) Add the dry powder to sodium potassium water glass and stir evenly, then add the anti-shrinkage agent, stir evenly to obtain a slurry, and set aside; (3) After foaming the foaming agent, mix it evenly with the slurry to obtain alkali-activated foamed concrete.

15. The method for preparing low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 14, characterized in that, In step (2), the dry powder is added to sodium potassium water glass and stirred for 1 to 5 minutes; after adding the anti-shrinkage agent, stirring is continued for 1 to 3 minutes to obtain the slurry.

16. The method for preparing low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 14 or 15, characterized in that, In step (3), the foaming method is to stir the foaming agent at a speed of 300~1000 rpm for 1~2 minutes.

17. The method for preparing low-shrinkage, lightweight, high-strength alkali-activated foamed concrete according to claim 14 or 15, characterized in that, In step (3), the foaming agent after foaming is mixed with the slurry and stirred for 1 to 3 minutes.

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