A waste mud-based geopolymer concrete and a preparation method thereof

Abstract

The application provides a kind of based on waste mud geopolymer concrete and its preparation method, belong to geopolymer concrete technical field.The raw material of the based on waste mud geopolymer concrete of the application includes cementitious material, alkali activator, mud filter cake, aggregate, water, wherein the cementitious material is fly ash and slag powder, the dosage of fly ash in cementitious material is 30-60%, the dosage of slag powder in based on waste mud geopolymer concrete is 99-200kg / cm 3 , the mass ratio of cementitious material, alkali activator, mud filter cake and aggregate is 1:0.38-0.60:1.0-1.1:4.5-4.7, the initial water-binder ratio of based on waste mud geopolymer concrete is 0.40-0.44.The application realizes the reuse of waste mud, and the compressive strength, tensile strength and flexural strength of the prepared based on waste mud geopolymer concrete are all high, which meets the use requirements of concrete.

Description

Technical Field

[0001] This invention relates to the field of geopolymer concrete technology, and in particular to a geopolymer concrete based on waste mud and its preparation method. Background Technology

[0002] Drilled cast-in-place piles are a widely applicable type of pile foundation, suitable for various geological conditions. They can be used to construct pile foundations of any diameter and length, meeting the bearing capacity requirements of high-rise, large-span, and long-distance structures. During the construction of drilled cast-in-place piles, a large amount of engineering mud, composed of water, bentonite, and admixtures, is required to effectively suppress groundwater seepage, ensure timely removal of waste material from the borehole, and prevent borehole wall collapse. Engineering mud maintains good physical and chemical properties initially; however, as it is mixed with soil and rock debris from underground sedimentary layers, its properties gradually deteriorate until it no longer meets usage requirements, at which point it becomes waste mud. The amount of engineering mud used depends on the borehole diameter, depth, and treatment method, generally being 3 to 5 times the borehole volume. Statistics show that constructing a 200km high-speed railway would generate 7.2 to 12 million cubic meters of waste mud. Improper disposal of waste mud can not only affect the construction progress but also have adverse effects on the environment, posing a serious challenge to waste mud treatment.

[0003] Currently, research on waste mud treatment methods mainly focuses on mechanical treatment, flocculation treatment, and solidification treatment. Mechanical treatment requires large-scale machinery, has high site requirements, and incurs significant costs, significantly increasing construction costs. While flocculation treatment is lower in cost and has a simpler construction process, the flocculated and dewatered mud still cannot be properly treated, and some inorganic flocculants contain metal ions, which may cause secondary pollution. Solidification treatment is a relatively suitable method; the solidified waste mud can be used as roadbed filler, garden soil, and wall materials, achieving the goal of waste reuse. Traditional solidifying agents are usually made from materials such as cement, lime, and gypsum; however, the production of these materials not only consumes a large amount of natural resources but also generates polluting gases (NOx). x SO x Waste mud and CO2 exacerbate environmental pollution and the greenhouse effect. Therefore, developing a geopolymer concrete based on waste mud to achieve the comprehensive utilization of waste mud is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a polymer concrete based on waste mud and its preparation method, so as to solve the technical problems of waste mud treatment process consuming natural resources and generating polluting gases in the prior art.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a polymer concrete based on waste mud, the raw materials of which include cementitious materials, alkali activator, mud filter cake, aggregate, and water;

[0007] The cementing material is fly ash and slag powder, and the amount of slag powder in the cementing material is 30-60%.

[0008] The slag powder is added at a dosage of 99–200 kg / cm³ in waste mud-based geopolymer concrete. 3 ;

[0009] The mass ratio of the cementitious material, alkali activator, mud filter cake, and aggregate is 1:0.38-0.60:1.0-1.1:4.5-4.7;

[0010] The initial water-cement ratio of the polymer concrete based on waste mud is 0.40 to 0.44.

[0011] Preferably, the alkaline activator is water glass and sodium hydroxide, wherein the mass ratio of water glass to sodium hydroxide is 105-163:15-33.

[0012] Preferably, the modulus of the alkali activator is 1.1 to 1.4.

[0013] Preferably, the mud filter cake is prepared as follows: the flocculant solution and waste mud are mixed until the waste mud particles no longer settle, and then filtered to obtain the mud filter cake.

[0014] Preferably, the concentration of the flocculant solution is 0.1-0.3%; the flocculant comprises one or more of APAM, CPAM and NPAM.

[0015] Preferably, the volume ratio of the flocculant solution to the waste mud is 3 to 8:20.

[0016] Preferably, the moisture content of the mud filter cake is 45-55%.

[0017] Preferably, the aggregate is manufactured sand and crushed stone, wherein the sand ratio is 0.3 to 0.5.

[0018] Preferably, the fineness modulus of the manufactured sand is 2.7; and the particle size of the crushed stone is 5-20 mm.

[0019] This invention provides a method for preparing polymer concrete based on waste mud slurry, comprising the following steps:

[0020] (1) Mix sodium hydroxide and water glass, and after the sodium hydroxide is completely dissolved, seal and store to obtain an alkaline activator;

[0021] (2) Mix the mud filter cake and aggregate, stir evenly, then add the cementitious material and alkali activator in sequence, and finally pour into the mold.

[0022] The beneficial effects of this invention are:

[0023] (1) This invention uses fly ash and slag powder as precursors, water glass and NaOH as alkali activators, and manufactured sand and graded crushed stone as aggregates. It utilizes the filter cake of flocculated and dewatered mud to replace part of the precursors to prepare polymer concrete based on waste mud, thereby realizing the reuse of waste mud. Moreover, the prepared polymer concrete based on waste mud has a compressive strength of up to 42.01 MPa, a tensile strength of up to 2.51 MPa, and a flexural strength of up to 3.02 MPa.

[0024] (2) In the process of preparing polymer concrete based on waste mud using waste mud, the present invention does not generate polluting gases, thus realizing the comprehensive utilization of waste mud. Attached Figure Description

[0025] Figure 1 The images show the failure morphology of the compressive strength test of polymer concrete based on waste mud obtained in Examples 4, 11 and 14, where a is Example 4, b is Example 11 and c is Example 14.

[0026] Figure 2 The following are trend graphs showing the influence of slag powder content, alkali activator content, and alkali activator modulus on the cubic compressive strength: a) shows the influence of slag powder content, b) shows the influence of alkali activator content, and c) shows the influence of alkali activator modulus.

[0027] Figure 3 The images show the failure morphology of the tensile strength test of polymer concrete based on waste mud obtained in Examples 4, 11 and 14, where a is Example 4, b is Example 11 and c is Example 14.

[0028] Figure 4 The following are trend graphs showing the effects of slag powder content, alkali activator content, and alkali activator modulus on splitting tensile strength: a) shows the effect of slag powder content, b) shows the effect of alkali activator content, and c) shows the effect of alkali activator modulus.

[0029] Figure 5 The images show the failure morphology of the flexural strength test of the polymer concrete based on waste mud obtained in Examples 4, 11 and 14, where a is Example 4, b is Example 11 and c is Example 14.

[0030] Figure 6 The following are trend graphs showing the effects of slag powder content, alkali activator content, and alkali activator modulus on splitting flexural strength: a) shows the effect of slag powder content, b) shows the effect of alkali activator content, and c) shows the effect of alkali activator modulus.

[0031] Figure 7 The images show the appearance morphology of the waste mud-based geopolymer concrete prepared in Example 4 after undergoing different freeze-thaw cycles, where a represents 25 freeze-thaw cycles and b represents 50 freeze-thaw cycles.

[0032] Figure 8 The images show the appearance morphology of the waste mud-based geopolymer concrete obtained in Example 11 after undergoing different freeze-thaw cycles, where a represents 25 freeze-thaw cycles, b represents 50 freeze-thaw cycles, c represents 75 freeze-thaw cycles, and d represents 100 freeze-thaw cycles.

[0033] Figure 9 The images shown are of the appearance morphology of the waste mud-based geopolymer concrete prepared in Example 14 after undergoing different freeze-thaw cycles, where a represents 25 freeze-thaw cycles, b represents 50 freeze-thaw cycles, c represents 100 freeze-thaw cycles, and d represents 125 freeze-thaw cycles.

[0034] Figure 10 The following are trend graphs showing the effects of slag powder content, alkali activator content, and alkali activator modulus on the mass loss rate after 50 freeze-thaw cycles: a represents the effect of slag powder content, b represents the effect of alkali activator content, and c represents the effect of alkali activator modulus.

[0035] Figure 11 The following are trend graphs showing the effects of slag powder content, alkali activator content, and alkali activator modulus on the relative dynamic elastic modulus after 50 freeze-thaw cycles: a represents the effect of slag powder content, b represents the effect of alkali activator content, and c represents the effect of alkali activator modulus.

[0036] Figure 12 The graphs show the influence trends of slag powder content, alkali activator content, and alkali activator modulus on the seepage height, where a represents the influence trend of slag powder content, b represents the influence trend of alkali activator content, and c represents the influence trend of alkali activator modulus.

[0037] Figure 13 Microscopic morphology images of waste mud-based geopolymer concrete prepared in Examples 4, 11 and 14, where a is Example 4, b is Example 11 and c is Example 14. Detailed Implementation

[0038] In this invention, the initial water-cement ratio is the ratio of the mass of added water, water contained in the alkali activator, and water contained in the mud filter cake to the mass of fly ash, slag powder, and solids contained in the mud filter cake; the slag powder dosage is the ratio of the mass of slag powder to the mass of fly ash and slag powder; the alkali activator dosage is the ratio of the mass of the alkali activator to the mass of solids contained in fly ash, slag powder, and mud filter cake; the alkali activator modulus is the molar ratio of SiO2 to Na2O; and the sand ratio is the ratio of the mass of manufactured sand to the mass of aggregate.

[0039] In this invention, the waste mud used comes from a bored pile construction site in Nanyang City, Henan Province, with a water content of 78.08%, a pH value of 8.46, and a relative density of 1.23 g / cm³. 3 The liquid limit is 19.7 and the plastic limit is 29.2.

[0040] The fly ash is Grade I fly ash produced by a power plant in Luoyang City, with a density of 78.08 g / cm³. 3 The bulk density is 0.78 g / cm³. 3 The average particle size is 23.18 μm, the water requirement is 93%, and the standard consistency is 29.2%.

[0041] The slag powder is S105 grade slag powder produced by a steel plant in Nanjing, with a density of 78.08 g / cm³. 3 The specific surface area is 8.46 m². 2 / kg, median particle size is 2.151μm, 28d activity index is 106%, and mobility ratio is 95%.

[0042] The water glass is produced by Zhengzhou Longxiang Ceramics Co., Ltd. in Henan Province. It has a modulus of 3.2, a solid content of 34.2%, and a specific gravity of 1.38 g / cm³. 3 .

[0043] The fine aggregate is manufactured sand from Dengfeng City, Henan Province, with a fineness modulus of 2.7, classifying it as medium sand. The coarse aggregate is crushed stone produced by a quarry in Nanyang, Henan Province, with a particle size range of 5–20 mm.

[0044] This invention provides a polymer concrete based on waste mud, the raw materials of which include cementitious materials, alkali activator, mud filter cake, aggregate, and water;

[0045] The cementing material is fly ash and slag powder, and the amount of slag powder in the cementing material is 30-60%.

[0046] The slag powder is added at a dosage of 99–200 kg / cm³ in waste mud-based geopolymer concrete. 3 ;

[0047] The mass ratio of the cementitious material, alkali activator, mud filter cake, and aggregate is 1:0.38-0.60:1.0-1.1:4.5-4.7;

[0048] The initial water-cement ratio of the polymer concrete based on waste mud is 0.40 to 0.44.

[0049] In this invention, the amount of slag powder in the cementitious material is preferably 30%, 40%, 50% or 60%, and more preferably 40%, 50% or 60%.

[0050] In this invention, the preferred dosage of slag powder in waste mud-based geopolymer concrete is 132–199 kg / cm³. 3 Further preferred values ​​are 165.83–198.99 kg / cm³. 3 .

[0051] In this invention, the preferred mass ratio of the cementitious material, alkali activator, mud filter cake, and aggregate is 1:0.40-0.57:1.01-1.09:4.55-4.65; the preferred initial water-cement ratio of the polymer concrete based on waste mud is 0.41-0.43, and more preferably 0.42.

[0052] In this invention, the alkaline activator is water glass and sodium hydroxide, wherein the mass ratio of water glass to sodium hydroxide is 105-163:15-33, preferably 110-143:17-26, and more preferably 122-140:20-23.

[0053] In this invention, the amount of alkali activator is preferably 25-37%, preferably 25%, 29%, 33% or 37%, and more preferably 29% or 33%.

[0054] In this invention, the modulus of the alkali activator is 1.1 to 1.4, preferably 1.1, 1.2, 1.3 or 1.4, and more preferably 1.2, 1.3 or 1.4.

[0055] In this invention, the mud filter cake is prepared as follows: the flocculant solution and waste mud are mixed until the waste mud particles no longer settle, and then filtered to obtain the mud filter cake.

[0056] In this invention, the concentration of the flocculant solution is 0.1-0.3%, preferably 0.1%; the flocculant comprises one or more of APAM, CPAM and NPAM, preferably APAM and / or CPAM, and more preferably APAM.

[0057] In this invention, the volume ratio of the flocculant solution to the waste mud is 3-8:20, preferably 4-7:20, and more preferably 5-6:20.

[0058] In this invention, the moisture content of the mud filter cake is 45-55%, preferably 46-54%, and more preferably 48-52%.

[0059] In this invention, the aggregate is manufactured sand and crushed stone, wherein the sand ratio is 0.3 to 0.5, preferably 0.4.

[0060] In this invention, the fineness modulus of the manufactured sand is 2.7; the particle size of the crushed stone is 5-20 mm, preferably 8-18 mm, and more preferably 10-15 mm.

[0061] This invention provides a method for preparing polymer concrete based on waste mud slurry, comprising the following steps: mixing mud filter cake and aggregate, stirring evenly, then sequentially adding cementitious materials and alkali activator, and finally casting into molds.

[0062] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0063] Example 1

[0064] A 0.1% APAM flocculant solution was mixed with waste sludge, with a volume ratio of APAM flocculant solution to waste sludge of 1:4. The mixture was kept until the waste sludge particles no longer settled. After filtration, a sludge filter cake was obtained with a moisture content of 50.3%.

[0065] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 232.16 kg / cm³ 3 Slag powder 99.49 kg / cm³ 3 The water glass concentration is 105.70 kg / cm³. 3 Sodium hydroxide concentration: 21.86 kg / cm³ 3 The crushed stone has a particle size of 6-15mm. Sodium hydroxide and water glass are mixed and sealed after the sodium hydroxide is completely dissolved to obtain an alkali activator. Finally, mud filter cake, manufactured sand and crushed stone are mixed and stirred evenly. Then fly ash and slag powder are added and stirred for 2 minutes. After that, the alkali activator is added and finally the mixture is poured into molds.

[0066] Example 2

[0067] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0068] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 232.16 kg / cm³ 3 Slag powder 99.49 kg / cm³ 3 The water glass concentration is 125.32 kg / cm³. 3 Sodium hydroxide concentration: 22.64 kg / cm³ 3 The crushed stone has a particle size of 9–18 mm and is prepared using the same method as in Example 1.

[0069] Example 3

[0070] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0071] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 232.16 kg / cm³ 3 Slag powder 99.49 kg / cm³ 3 The water glass concentration is 145.33 kg / cm³. 3 Sodium hydroxide concentration is 23.04 kg / cm³. 3 The crushed stone has a particle size of 5-13 mm and is prepared using the same method as in Example 1.

[0072] Example 4

[0073] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0074] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 232.16 kg / cm³ 3 Slag powder 99.49 kg / cm³ 3 The water glass concentration is 165.66 kg / cm³. 3 Sodium hydroxide concentration: 23.12 kg / cm³ 3 The crushed stone has a particle size of 8-20 mm and is prepared using the same method as in Example 1.

[0075] Example 5

[0076] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0077] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 198.99 kg / cm³ 3 Slag powder 132.66 kg / cm³ 3 The water glass concentration is 108.04 kg / cm³. 3 Sodium hydroxide concentration is 19.52 kg / cm³. 3 The crushed stone has a particle size of 6-15 mm and is prepared using the same method as in Example 1.

[0078] Example 6

[0079] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0080] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 198.99 kg / cm³ 3 Slag powder 132.66 kg / cm³ 3 The water glass concentration is 122.61 kg / cm³. 3 Sodium hydroxide concentration: 25.36 kg / cm³ 3 The crushed stone has a particle size of 9–18 mm and is prepared using the same method as in Example 1.

[0081] Example 7

[0082] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0083] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 198.99 kg / cm³ 3 Slag powder 132.66 kg / cm³ 3 The water glass concentration is 147.75 kg / cm³. 3 Sodium hydroxide concentration: 20.62 kg / cm³ 3The crushed stone has a particle size of 5-13 mm and is prepared using the same method as in Example 1.

[0084] Example 8

[0085] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0086] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 198.99 kg / cm³ 3 Slag powder 132.66 kg / cm³ 3 The water glass concentration is 162.95 kg / cm³. 3 Sodium hydroxide concentration: 25.83 kg / cm³ 3 The crushed stone has a particle size of 8-20 mm and is prepared using the same method as in Example 1.

[0087] Example 9

[0088] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0089] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 165.83 kg / cm³ 3 Slag powder 165.83 kg / cm³ 3 The water glass concentration is 110.10 kg / cm³. 3 Sodium hydroxide concentration is 17.46 kg / cm³. 3 The crushed stone has a particle size of 4-13 mm and is prepared using the same method as in Example 1.

[0090] Example 10

[0091] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0092] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 165.83 kg / cm³ 3 Slag powder 165.83 kg / cm³ 3 The water glass concentration is 129.84 kg / cm³.3 Sodium hydroxide concentration is 18.12 kg / cm³. 3 The crushed stone has a particle size of 8-20 mm and is prepared using the same method as in Example 1.

[0093] Example 11

[0094] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0095] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 165.83 kg / cm³ 3 Slag powder 165.83 kg / cm³ 3 The water glass concentration is 139.52 kg / cm³. 3 Sodium hydroxide concentration is 28.86 kg / cm³. 3 The crushed stone has a particle size of 9–18 mm and is prepared using the same method as in Example 1.

[0096] Example 12

[0097] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0098] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 165.83 kg / cm³ 3 Slag powder 165.83 kg / cm³ 3 The water glass concentration is 159.89 kg / cm³. 3 Sodium hydroxide concentration: 28.89 kg / cm³ 3 The crushed stone has a particle size of 5-13 mm and is prepared using the same method as in Example 1.

[0099] Example 13

[0100] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0101] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 132.66 kg / cm³ 3Slag powder 198.99 kg / cm³ 3 The water glass concentration is 111.93 kg / cm³. 3 Sodium hydroxide concentration is 15.62 kg / cm³. 3 The crushed stone has a particle size of 6-18 mm and is prepared using the same method as in Example 1.

[0102] Example 14

[0103] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0104] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 132.66 kg / cm³ 3 Slag powder 198.99 kg / cm³ 3 The water glass concentration is 127.72 kg / cm³. 3 Sodium hydroxide is 20.25 kg / cm³. 3 The crushed stone has a particle size of 10-16 mm and is prepared using the same method as in Example 1.

[0105] Example 15

[0106] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0107] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3 918.41 kg / cm³ of crushed stone 3 fly ash 132.66 kg / cm³ 3 Slag powder 198.99 kg / cm³ 3 The water glass concentration is 142.61 kg / cm³. 3 Sodium hydroxide concentration: 25.77 kg / cm³ 3 The crushed stone has a particle size of 7-14 mm and is prepared using the same method as in Example 1.

[0108] Example 16

[0109] The mud filter cake was prepared using the same method as in Example 1, and the moisture content of the mud filter cake was 50.3%.

[0110] First, weigh each raw material according to the specified dosage; the mud filter cake is 359.31 kg / cm³. 3 612.27 kg / cm³ of manufactured sand 3918.41 kg / cm³ of crushed stone 3 fly ash 132.66 kg / cm³ 3 Slag powder 198.99 kg / cm³ 3 The water glass concentration is 156.43 kg / cm³. 3 Sodium hydroxide concentration: 32.36 kg / cm³ 3 The crushed stone has a particle size of 10-20 mm and is prepared using the same method as in Example 1.

[0111] Table 1. Raw material admixtures in waste mud-based geopolymer concrete prepared in Examples 1-16

[0112]

[0113] In Table 1, S represents the slag powder content, A represents the alkali activator content, and M represents the alkali activator modulus. For example, S30A25M1.1 means that the slag powder content is 30%, the alkali activator content is 25%, and the alkali activator modulus is 1.1.

[0114] Performance testing:

[0115] (1) Test method for compressive strength: The test method for cube compressive strength was conducted in accordance with the national standard "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081-2019). A cube specimen with a side length of 100 mm was used for the cube compressive strength test. The instrument used was a WHY-2000 microcomputer-controlled pressure testing machine manufactured by Shanghai Hualong Company, and the loading rate was set to 0.5 MPa / s. After the specimen had been cured for 28 days, it was removed and wiped clean. The test was conducted using the side surface at the time of molding as the bearing surface. The cube compressive strength was calculated according to formula (1).

[0116]

[0117] In the formula: f cu —Cube compressive strength (MPa);

[0118] F—the failure load of the specimen (N);

[0119] A—Bearing area of ​​the specimen (mm²) 2 ).

[0120] Because this experiment used non-standard specimens of 100mm×100mm×100mm, the calculation results should be multiplied by a conversion factor of 0.95. Three cubic specimens were cast for each mix proportion, and the final test result was the arithmetic mean of the compressive strength of the three cubic specimens.

[0121] (2) Tensile strength test method: The splitting tensile strength test method shall be carried out in accordance with the national standard "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081-2019). The splitting tensile strength test shall use a cube specimen with a side length of 100 mm. The instrument used shall be the same as that used in the cube compressive strength test. The loading rate shall be set to 0.05 MPa / s. At the beginning of the test, the specimen with a curing age of 28 days shall be taken out and placed in the center of the lower pressure plate of the testing machine. Then, the steel pad and wooden pad shall be placed on the center line of the specimen. The position of the upper pressure plate shall be adjusted until contact equilibrium is reached. The pressure machine shall be started for the test. The data shall be recorded after the specimen is destroyed. The splitting tensile strength shall be calculated according to formula (2).

[0122]

[0123] In the formula: f tx — Splitting tensile strength (MPa);

[0124] F—Specimen failure load (N);

[0125] A—Speed ​​specimen fracture surface area (mm²) 2 ).

[0126] Because this experiment used non-standard specimens of 100mm×100mm×100mm, the calculation results should be multiplied by a conversion factor of 0.85. Three cubic specimens were cast for each mix proportion, and the final test result was the arithmetic mean of the splitting tensile strength of the three specimens.

[0127] (3) Flexural strength test method: The flexural strength test method was conducted according to the national standard "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081-2019). A 100mm×100mm×400mm prism specimen was used for the flexural strength test. The instrument used was a WHY-300 microcomputer-controlled pressure testing machine manufactured by Shanghai Hualong Company, with a loading rate set to 0.05MPa / s. First, the specimen, cured for 28 days, was removed, its surface was dried, and it was placed on a support. The pressure machine was started for the test, and the data was recorded after the specimen failed. The flexural strength was calculated according to formula (3).

[0128]

[0129] In the formula: f f —Flexural strength (MPa);

[0130] F—Specimen failure load (N);

[0131] l—span between supports (mm);

[0132] b—Specimen cross-sectional width (mm);

[0133] h — Specimen cross-sectional height (mm).

[0134] Because this experiment used non-standard specimens of 100mm×100mm×400mm, the calculation results should be multiplied by a conversion factor of 0.85. Three prism specimens were cast for each mix proportion, and the final test result was the arithmetic mean of the flexural strength of the three specimens.

[0135] (4) Freeze-thaw resistance test method: The rapid freezing method for freeze-thaw resistance test shall be carried out in accordance with the "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082-2009). A 100mm×100mm×400mm prism specimen was used for the freeze-thaw resistance test. The instrument used was the HC-HDK type rapid freeze-thaw tester for concrete manufactured by Jianyan Huace Instrument Equipment Co., Ltd. When the curing age reached 24 days, the specimen was removed and soaked in clean water for 4 days. Then, the specimen was removed and the surface moisture was wiped off. The initial mass and transverse fundamental frequency of the specimen were recorded. The specimen was then placed in a specimen box, clean water was added, and the specimen box was placed in a freeze-thaw test chamber to begin the freeze-thaw resistance test. After every 25 freeze-thaw cycles, the specimen was removed, wiped clean, and the mass and transverse fundamental frequency of the specimen were measured. The specimen was then placed back in the specimen box, clean water was added, and the freeze-thaw resistance test continued. The freeze-thaw resistance test shall be stopped when any of the following three conditions occur:

[0136] (1) The freeze-thaw cycle reaches 300 times;

[0137] (2) The relative dynamic elastic modulus is less than 60%;

[0138] (3) The quality loss rate exceeds 5%.

[0139] The mass loss rate and relative dynamic elastic modulus of a single specimen are calculated according to equations (4) and (5), respectively.

[0140]

[0141] In the formula: ΔW n —The mass loss rate (%) of the specimen after n freeze-thaw cycles;

[0142] W n —The mass (g) of the specimen after n freeze-thaw cycles;

[0143] W0—Mass of the specimen (g) before the freeze-thaw cycle test.

[0144]

[0145] In the formula: P n —Relative dynamic elastic modulus (%) of the specimen after n freeze-thaw cycles;

[0146] f n—The transverse fundamental frequency (Hz) of the specimen after n freeze-thaw cycles;

[0147] f0—The transverse fundamental frequency (Hz) of the specimen before the freeze-thaw cycle test.

[0148] Three prism specimens were cast for each mix proportion, and the final test result was the arithmetic mean of the mass loss rate and relative dynamic elastic modulus of the three specimens.

[0149] (5) Test method for water permeability resistance: The water height method of the water permeability test in the national standard "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" (GB / T 50082-2009) was used. The test used frustum-shaped specimens with an upper diameter of 175mm, a lower diameter of 185mm, and a height of 150mm. The instrument used was the HP-4.0 automatic pressure-regulating concrete permeability tester manufactured by Shanghai Dongxing Building Materials Testing Equipment Co., Ltd. One day before the 28-day test age, the specimens were removed from the curing room and their surfaces were wiped clean. After the specimens dried, they were sealed with cement and grease, pressed into a steel mold using a press, and finally placed in the permeability tester for the test.

[0150] During the impermeability test, the water pressure should be maintained at 1.2 (±0.05) MPa. After 24 hours, the test block is removed, split open with a press, and watermarks are drawn with a waterproof pen. The seepage height at 10 measuring points is measured at equal intervals using a trapezoidal plate. The seepage height of a single test piece is calculated according to formula (6).

[0151]

[0152] In the formula: —Water seepage height of the specimen (mm);

[0153] h j —The water seepage height (mm) at the j-th measuring point of the specimen.

[0154] Six frustum specimens were cast for each mix proportion, and the final test result was the arithmetic mean of the seepage height of the six specimens.

[0155] Table 2. Test results of compressive strength, tensile strength, and flexural strength

[0156]

[0157]

[0158] from Figure 1(a) It can be seen that the S30A37M1.4 (Example 4) group specimens exhibited brittle fracture characteristics. When the specimens were subjected to compressive failure, multiple cracks appeared on the surface, the edges and corners were directly crushed, some small pieces fell off the surface of the specimens, a large number of powdery particles appeared around the specimens, and obvious overall deformation occurred. The final failure mode of the S50A33M1.1 (Example 11) group specimens is as follows: Figure 1 As shown in (b), when the press load is increased to the peak value, a large number of fragments fall off the surface of the specimen and are scattered around the specimen, forming a hoop effect, and the whole does not show a large degree of deformation. Figure 1 As shown in (c), the S60A29M1.3 (Example 14) group specimens exhibited a clear hoop effect morphology. When the specimens were damaged, small fragments crushed on the surface were scattered everywhere, and large pieces that were cracked fell off the surface of the specimens, accompanied by a "crunching" sound, which showed typical brittle fracture characteristics.

[0159] from Figure 2 (a) It can be seen that the average cubic compressive strength of the polymer concrete based on waste slurry gradually increases with the increase of slag powder content. When the slag powder content is 60%, the average cubic compressive strength of the polymer concrete based on waste slurry is 35.03 MPa, which is 70.4% higher than that of 30% slag powder content. This is because the degree of polymerization of silicon-oxygen tetrahedra and aluminum-oxygen tetrahedra in slag powder is lower than that in fly ash, making them easier to be activated by alkali activators, generating more gel, and thus filling the voids between aggregates. From the perspective of chemical composition, slag powder has a high CaO content, which easily reacts with Si and Al in the system to form hydrated calcium silicate (CSH) gel or hydrated calcium aluminosilicate (CASH) gel. C-(A)-SH gel, as a coagulation nucleus, can promote the formation of hydrated sodium aluminosilicate (NASH) gel, thus increasing the compressive strength of the entire system. From a microscopic perspective, slag powder has an irregular flaky structure, while fly ash has a smooth spherical structure. The contact area between slag powder and alkali activator is larger than that of fly ash. Therefore, the reaction degree and reaction rate of slag powder are higher, which makes the compressive strength increase with the increase of slag powder content.

[0160] from Figure 2(b) It can be seen that with the increase of alkali activator dosage, the average cubic compressive strength of the waste mud-based geopolymer concrete shows a trend of first increasing and then decreasing. When the alkali activator dosage is 29%, the average cubic compressive strength reaches its maximum value. As the alkali activator dosage increases to 33% and 37%, the average cubic compressive strength decreases by 8.5% and 9.6%, respectively, with a relatively small decrease. The alkali activator can activate the activity of fly ash and slag powder, participate in the geopolymerization reaction, and thus generate geopolymer gel, giving the matrix a certain strength. When the alkali activator dosage is small, the activation effect is poor, resulting in insufficient disintegration of the glassy matrix of fly ash and slag powder, thus leading to lower compressive strength. When the alkali activator dosage is too large, the excessively fast reaction rate causes aluminosilicate products to deposit on the surface of fly ash and slag powder, hindering Si and Al from further participating in the geopolymerization reaction and affecting the formation of new gel. Furthermore, unreacted alkali activators remaining inside the concrete can easily cause efflorescence, leading to an increase in the number of pores in the matrix and a decrease in density, thus adversely affecting the strength of the geopolymer concrete.

[0161] from Figure 2 (c) It can be seen that the average cubic compressive strength of the waste mud-based geopolymer concrete first increases and then decreases with the increase of the alkali activator modulus. When the alkali activator modulus is 1.3, the average cubic compressive strength reaches its maximum value. As the alkali activator modulus increases to 1.4, the average cubic compressive strength decreases by 16.9%. The low-polymerization degree of silicate tetrahedron monomers in the alkali activator can promote the condensation polymerization of silicate and aluminosilicate oligomers, improve the efficiency of the geopolymerization reaction, and make the concrete denser. When the alkali activator modulus increases from 1.1 to 1.3, the content of low-polymerization degree silicate tetrahedron monomers in the alkali activator gradually increases, thus increasing the compressive strength of the waste mud-based geopolymer concrete. However, when the alkali activator modulus increases to a certain extent, the content of low-polymerization degree silicate tetrahedron monomers does not increase accordingly, but decreases instead, thus adversely affecting the concrete strength. When the modulus of the alkali activator increases from 1.3 to 1.4, the pH value of the alkali activator decreases excessively, and the high-polymerization tetrahedron monomers increase while the low-polymerization tetrahedron monomers decrease, thereby affecting the solubility of fly ash and slag powder themselves, resulting in a decrease in the compressive strength of polymer concrete based on waste mud.

[0162] Combined Table 2 and Figure 2 It can be concluded that the slag powder content has the greatest impact on the cubic compressive strength, followed by the alkali activator modulus, while the alkali activator content has the least impact on the cubic compressive strength. For polymer concrete based on waste mud, the higher the cubic compressive strength, the better. That is, the optimal combination is S60A29M1.3, which means the slag powder content is 60%, the alkali activator content is 29%, and the alkali activator modulus is 1.3.

[0163] Figure 3The tensile failure modes of waste mud polymer concrete specimens in groups S30A37M1.4, S50A33M1.1, and S60A29M1.3 were demonstrated. The specimen in group S30A37M1.4 (Example 4) exhibited brittle failure characteristics. Before failure, three microcracks appeared near the bearing axis on the side of the specimen and rapidly expanded. Two of these cracks developed into through cracks, leading to specimen failure and the detachment of a large piece, forming a significant gap. The failure modes of the specimens in groups S50A33M1.1 (Example 11) and S60A29M1.3 (Example 14) were similar. Before the load reached its peak, one or two cracks appeared near the bearing axis on the side of the specimen. One of these cracks rapidly developed into a through crack, directly splitting the specimen in two, accompanied by the ejection of small fragments, exhibiting obvious brittle failure characteristics. Compared with group S30A37M1.4, the specimens in groups S50A33M1.1 and S60A29M1.3 were more complete.

[0164] Depend on Figure 4 (a) It can be seen that the average splitting tensile strength of the waste slurry-based geopolymer concrete gradually increases with the increase of slag powder content. When the slag powder content is 60%, the average splitting tensile strength of the waste slurry-based geopolymer concrete is 2.31 MPa, which is 56.1% higher than that of 30% slag powder content. This is because slag powder has higher activity than fly ash, and its Si and Al components are more easily dissolved, which greatly promotes the geopolymerization reaction and gel formation. In addition, compared with fly ash, slag powder has a smaller particle size and a larger specific surface area. When replacing fly ash in equal amounts, it can increase the reaction rate, increase reaction products, fill cracks in the matrix, improve the density of concrete, reduce the adverse effect of cracks on splitting tensile strength, and thus improve the tensile properties of waste slurry-based geopolymer concrete. + In comparison, Ca 2+ It possesses stronger charge balancing and electrostatic attraction, which can accelerate the formation of geopolymer gels. The higher the CaO content in the cementitious material, the faster the geopolymer reaction and the more gel is formed. Since the main component of slag powder is CaO, increasing the slag powder content is beneficial to improving the splitting tensile strength of waste mud-based geopolymer concrete.

[0165] Depend on Figure 4(b) It can be seen that with the increase of alkali activator dosage, the average splitting tensile strength of the waste mud-based geopolymer concrete shows a trend of first increasing and then decreasing. When the alkali activator dosage is 33%, the average splitting tensile strength reaches its maximum value, which is comparable to the average splitting tensile strength when the alkali activator dosage is 29%. As the alkali activator dosage increases to 37%, the average splitting tensile strength decreases by 4.5%. This is because, within a certain range, with the increase of alkali activator dosage, the silica-alumina materials dissolve more fully, forming more geopolymer gel, which fully fills the voids between aggregates, making the matrix more compact, thus increasing the average splitting tensile strength. However, when the alkali activator dosage is too high, the excess alkali solution will adhere to the aggregate surface, leading to a decrease in the bond strength between the aggregate and the paste, causing micro-cracks to appear in the concrete during hardening, thereby reducing the average splitting tensile strength of the waste mud-based geopolymer concrete. Excess alkali activator reacts with CO2 in the air to form carbonates, which form a hardened body with lower strength inside the concrete matrix, thus reducing the splitting tensile strength of the concrete.

[0166] Depend on Figure 4 (c) It can be seen that with the increase of the alkali activator modulus, the average splitting tensile strength of the waste slurry-based geopolymer concrete shows a trend of first increasing and then decreasing. When the alkali activator modulus is 1.3, the average splitting tensile strength reaches its maximum value. As the alkali activator modulus increases to 1.4, the average splitting tensile strength decreases by 11.0%. Within a certain range, with the increase of the alkali activator modulus, the absolute content of SiO2 in the alkali activator increases, resulting in an increase in low-polymerization degree silica tetrahedrons. This promotes the disintegration of the glass phase in the aluminosilicate material and the formation of the geopolymer gel, further strengthening the slurry structure and enhancing the bond between the slurry and aggregate, thereby improving the tensile properties of the waste slurry-based geopolymer concrete. However, when the alkali activator modulus is too high, the solution pH value is low, and the content of low-polymerization degree silica tetrahedrons is low, which has an adverse effect on the dissolution of the aluminosilicate material, thus hindering the formation of the geopolymer gel structure and the development of matrix strength.

[0167] Combined Table 2 and Figure 4 It can be seen that the slag powder content and the modulus of the alkali activator have extremely significant effects on the splitting tensile strength, while the alkali activator content has a relatively small effect.

[0168] Figure 5The flexural failure morphology of polymer-based specimens from waste mud slurry groups S30A37M1.4, S50A33M1.1, and S60A29M1.3 was demonstrated. The surface cracks of the S30A37M1.4 (Example 4) specimens exhibited a larger angle of inclination and a distinct serrated appearance, while the surface cracks of the S50A33M1.1 (Example 11) and S60A29M1.3 (Example 14) specimens showed a smaller angle of inclination. Furthermore, the cracks in the S30A37M1.4 and S50A33M1.1 specimens extended from the bottom to the top, but did not completely fracture the specimen. In contrast, the cracks in the S60A29M1.3 specimen penetrated directly from the bottom, breaking the specimen in two.

[0169] Depend on Figure 6 (a) It can be seen that the average flexural strength of the polymer concrete based on waste slurry gradually increases with the increase of slag powder content. When the slag powder content is 60%, the average flexural strength of the polymer concrete based on waste slurry is 2.78 MPa, which is 50.3% higher than that of the 30% slag powder content.

[0170] Depend on Figure 6 (b) It can be seen that with the increase of alkali activator dosage, the average flexural strength of polymer concrete based on waste mud shows a trend of first increasing and then decreasing. When the alkali activator dosage is 33%, the average flexural strength reaches its maximum value. As the alkali activator dosage increases to 37%, the average flexural strength decreases by 4.9%.

[0171] Depend on Figure 6 (c) It can be seen that as the modulus of the alkali activator increases, the average flexural strength of the polymer concrete based on waste mud first increases and then decreases. When the modulus of the alkali activator is 1.3, the average flexural strength reaches its maximum value. As the modulus of the alkali activator increases to 1.4, the average splitting tensile strength decreases by 9.9%.

[0172] Combined Table 2 and Figure 6 It can be seen that the slag powder content and the alkali activator modulus have a very significant impact on flexural strength, while the alkali activator content has a smaller impact. The order of influence on flexural strength is: slag powder content > alkali activator modulus > alkali activator content.

[0173] Table 3. Mass loss rate (%) of polymer concrete based on waste mud.

[0174]

[0175]

[0176] Table 4. Relative dynamic elastic modulus (%) of polymer concrete based on waste mud slurry

[0177]

[0178] Figure 7 , Figure 8 , Figure 9 The images show the surface morphology of waste mud geopolymer concrete specimens from groups S30A37M1.4 (Example 4), S50A33M1.1 (Example 11), and S60A29M1.3 (Example 14) after different freeze-thaw cycles. As can be seen from the figures, at the beginning of the freeze-thaw cycle, a large amount of mortar detached from the surface of the S30A37M1.4 specimens, clearly exposing the coarse aggregate. In contrast, only a small amount of mortar detached from the surfaces of the S50A33M1.1 and S60A29M1.3 specimens, with the S60A29M1.3 specimen showing the best integrity. After 50 freeze-thaw cycles, the mortar on the surface of the S30A37M1.4 specimens almost completely detached, resulting in a very rough surface, with some coarse aggregate even falling off. The surfaces of the S50A33M1.1 and S60A29M1.3 specimens remained relatively intact. With increasing freeze-thaw cycles, the mortar detachment from the surface of the S50A33M1.1 and S60A29M1.3 specimens became more severe, gradually exposing the coarse aggregate. When the number of freeze-thaw cycles reached 75, only a small amount of mortar remained on the surface of the S50A33M1.1 specimens. After 100 cycles, the surface mortar almost completely detached, while a small amount of mortar remained on the surface of the S60A29M1.3 specimens, and the surface roughness of the S60A29M1.3 specimens was less than that of the S50A33M1.1 specimens. When the number of freeze-thaw cycles reached 125, the mortar on the surface of the S60A29M1.3 specimens almost completely detached, resulting in poor specimen integrity.

[0179] Depend on Figure 10 As shown in (a) and 11(a), with the increase of slag powder content, the average mass loss rate of the geopolymer concrete based on waste mud gradually decreases and the average relative dynamic modulus of elasticity gradually increases after 50 freeze-thaw cycles. This is because slag powder has higher activity than fly ash, and its smaller particle size and larger specific surface area lead to a more complete geopolymerization reaction. Furthermore, the Ca dissolved from the slag powder... 2+ In the early stages of the geopolymerization reaction, multiphase condensation nuclei are formed, promoting the formation of amorphous aluminosilicate gels. These gels can refine the pores, making the internal structure of concrete more compact, thereby reducing the expansion pressure and osmotic pressure during the freeze-thaw process and improving the freeze-thaw resistance of concrete.

[0180] Depend on Figure 10As shown in (b) and 11(b), with the increase of alkali activator dosage, the average mass loss rate of the waste slurry-based geopolymer concrete after 50 freeze-thaw cycles shows a trend of first decreasing and then increasing, while the average relative dynamic modulus of elasticity shows a trend of first increasing and then decreasing. When the alkali activator dosage is low, the release rate of Si and Al in fly ash and slag powder is slow, and the geopolymerization reaction is insufficient, resulting in a relatively loose matrix structure, which in turn leads to poor freeze-thaw resistance of the waste slurry-based geopolymer concrete. With the increase of alkali activator dosage, the silica-alumina materials dissolve more fully, producing more gel, thereby filling the internal pores and improving the density of the concrete. When the alkali activator dosage is too high, the geopolymerization reaction rate accelerates, rapidly releasing a large amount of heat. The resulting thermal stress causes a large number of microcracks in the matrix, thereby reducing the freeze-thaw resistance of the waste slurry-based geopolymer concrete.

[0181] Depend on Figure 10 As shown in (c) and 11(c), with the increase of the alkali activator modulus, the average mass loss rate of the waste slurry-based geopolymer concrete after 50 freeze-thaw cycles shows a trend of first decreasing and then increasing, while the average relative dynamic elastic modulus shows a trend of first increasing and then decreasing. The freeze-thaw resistance of the waste slurry-based geopolymer concrete is closely related to the density of its structure, which is related to the silica-oxygen tetrahedrons and alumina-oxygen tetrahedrons in the reaction system. The products of the geopolymer reaction are mainly three-dimensional mesh-like aluminosilicate compounds, which are the main source of the good performance of concrete. When the alkali activator modulus increases, the content of low-polymerization silica-oxygen tetrahedrons in the alkali activator shows a trend of first increasing and then decreasing. Therefore, when the alkali activator modulus is low or high, a dense three-dimensional mesh-like structure cannot be formed, resulting in a decrease in the density of the waste slurry-based geopolymer concrete, thus affecting its freeze-thaw resistance. Therefore, when the alkali activator modulus is 1.3, the freeze-thaw resistance of the waste slurry-based geopolymer concrete is optimal.

[0182] Depend on Figure 12 (a) It can be seen that the average water penetration height of the waste mud-based geopolymer concrete gradually decreases with the increase of slag powder content. When the slag powder content is 60%, the average water penetration height of the waste mud-based geopolymer concrete is 54.5 mm, which is 34.9% lower than that with a slag powder content of 30%. This is because with the increase of slag powder content, the geopolymer reaction is more complete, and the amount of gel generated gradually increases. A large amount of gel fills the pores in the matrix and the interface transition zone, thereby blocking the water transport channels and improving the impermeability of the concrete.

[0183] Depend on Figure 12(b) It can be seen that with the increase of alkali activator dosage, the average seepage height of the geopolymer concrete based on waste mud first decreases and then increases. When the alkali activator dosage is 29%, the average seepage height reaches the minimum value. As the alkali activator dosage increases to 33% and 37%, the average seepage height increases by 3.8% and 5.3% respectively, with relatively small increases. When the alkali activator dosage is too small, it cannot fully activate the activity of fly ash and slag powder, resulting in a decrease in the density of the internal structure of the concrete, thereby reducing its impermeability. Excessive alkali activator will accelerate the geopolymer reaction rate, releasing a large amount of heat in a short time. The resulting thermal stress will cause more cracks in the matrix, providing channels for water transport and opportunities for connection of closed pores inside the concrete, thus reducing the impermeability of the concrete. In addition, the unreacted alkali activator remains inside the concrete. As the curing age of the specimen increases, the water in the alkali activator gradually evaporates, eventually forming pores inside the concrete, leading to an increase in the total porosity of the concrete, thus adversely affecting its impermeability.

[0184] Depend on Figure 12 (c) It can be seen that as the modulus of the alkali activator increases, the average water penetration height of the geopolymer concrete based on waste mud first decreases and then increases. When the modulus of the alkali activator is 1.3, the average water penetration height reaches its minimum value. As the modulus of the alkali activator increases to 1.4, the average water penetration height increases by 16.9%. The modulus of the alkali activator affects the pH value of the alkali activator and the number of oligomeric silica tetrahedrons, which are closely related to the amount of gel produced by the geopolymerization reaction. When the modulus of the alkali activator is too low or too high, a dense concrete structure cannot be formed, resulting in increased concrete permeability. A suitable modulus of the alkali activator can make the geopolymerization reaction more complete, reduce the water passage channels inside the concrete, and improve the impermeability of the concrete.

[0185] Depend on Figure 13(a) It can be seen that the S30A37M1.4 (Example 4) group specimen contains a large number of unreacted fly ash particles, with less gel produced by the geopolymerization reaction, and the overall structure is relatively loose, corresponding to the lowest 28-day cubic compressive strength (18.25 MPa). The small amount of gel cannot effectively bind the unreacted fly ash together, resulting in numerous accumulation pores at the boundaries of the fly ash particles, thus leading to lower concrete strength. From the SEM image of the S50A33M1.1 (Example 11) group specimen, many unreacted fly ash particles can still be observed; however, they are encapsulated by a large amount of gel, forming a relatively dense matrix structure. Compared with the S30A37M1.4 group, the S50A33M1.1 group specimen begins to show a plate-like gel structure, indicating that its matrix structure is beginning to develop in a flat, continuous, and dense direction, corresponding to a higher 28-day cubic compressive strength (30.66 MPa). Furthermore, the microstructure of the S30A37M1.4 and S50A33M1.1 specimens also showed pores formed due to fly ash reaction or fly ash particles detaching from the matrix. For example... Figure 13 As shown in (c), the matrix of the S60A29M1.3 (Example 14) group specimens exhibits a large-area plate-like gel structure. Compared to the S30A37M1.4 and S50A33M1.1 group specimens, the microstructure of the S60A29M1.3 group specimens is significantly smoother and denser, corresponding to the highest 28-day cubic compressive strength (42.01 MPa). By comparing the microstructures of the S30A37M1.4, S50A33M1.1, and S60A29M1.3 group specimens, it was found that the matrix structure of the three groups of concrete specimens gradually becomes smoother, more continuous, and denser. This is because the amount of gel generated by the geopolymer reaction gradually increases, and the large amount of gel can encapsulate the unreacted fly ash and slag powder, forming a dense plate-like structure. The smooth and dense matrix structure not only brings good mechanical properties but also improves the durability of concrete.

[0186] As can be seen from the above embodiments, the present invention provides a polymer concrete based on waste mud and its preparation method. The present invention realizes the reuse of waste mud, and the prepared polymer concrete based on waste mud has high compressive strength, tensile strength and flexural strength, which meets the requirements for concrete use.

[0187] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A type of polymer concrete based on waste mud slurry, characterized in that, Raw materials include cementitious materials, alkali activators, mud filter cake, aggregates, and water; The cementing material is fly ash and slag powder, and the amount of slag powder in the cementing material is 30-60%. The slag powder is added at a dosage of 99–200 kg / cm³ in waste mud-based geopolymer concrete. 3 ; The mass ratio of the cementitious material, alkali activator, mud filter cake, and aggregate is 1:0.38-0.60:1.0-1.1:4.5-4.7; The initial water-cement ratio of the polymer concrete based on waste mud is 0.40 to 0.44; The modulus of the alkaline activator is 1.1 to 1.4; The alkaline activator is water glass and sodium hydroxide, wherein the mass ratio of water glass to sodium hydroxide is 105-163:15-33; The method for preparing the mud filter cake is as follows: mix the flocculant solution and waste mud until the waste mud particles no longer settle, and then filter to obtain the mud filter cake; The moisture content of the mud filter cake is 45-55%.

2. The waste mud-based geopolymer concrete according to claim 1, characterized in that, The concentration of the flocculant solution is 0.1-0.3%; the flocculant contains one or more of APAM, CPAM and NPAM.

3. The waste mud-based geopolymer concrete according to claim 2, characterized in that, The volume ratio of the flocculant solution to the waste mud is 3 to 8:

20.

4. The waste mud-based geopolymer concrete according to claim 2 or 3, characterized in that, The aggregate is manufactured sand and crushed stone, wherein the sand ratio is 0.3 to 0.

5.

5. The waste mud-based geopolymer concrete according to claim 4, characterized in that, The fineness modulus of the sand is 2.7; the particle size of the crushed stone is 5-20 mm.

6. The method for preparing polymer concrete based on waste mud slurry according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Mix sodium hydroxide and water glass, and after the sodium hydroxide is completely dissolved, seal and store to obtain an alkaline activator; (2) Mix the mud filter cake and aggregate, stir evenly, then add the cementitious material and alkali activator in sequence, and finally pour into the mold.

Images