Single-component alkali-activated engineering residue soil geopolymer as well as preparation method and application thereof

Abstract

The invention provides a single-component alkali-activated engineering residue soil geopolymer as well as a preparation method and application thereof, and relates to the technical field of geopolymers. The single-component alkali-activated engineering residue soil geopolymer provided by the invention is prepared from the following raw materials in parts by mass: 100 parts of solid wastes; 0-6 parts of an alkali metal salt fluxing agent; based on sodium oxide, 3-6 parts of a solid alkali activator; 30 to 35 parts of water; the solid wastes comprise the following components in percentage by mass: 50-70% of engineering residue soil and 30-50% of slag; the engineering muck is calcined before being used, and when the calcination temperature is smaller than or equal to 800 DEG C, the dosage of the alkali metal salt fluxing agent is not 0, and the alkali metal salt fluxing agent is calcined after being mixed with the engineering muck. According to the invention, the engineering residue soil and the alkali metal salt fluxing agent are subjected to calcination treatment, slag is doped, the mixture reacts with the solid alkali activator to generate the gel material, the alkali activator technology is utilized, the ratio of the raw materials is controlled, and the compressive strength of the single-component alkali-activated engineering residue soil geopolymer is excellent.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization of building materials, and particularly relates to a single-component alkali-activated engineering slag geopolymers and its preparation method and application. Background Art

[0002] The amount of waste engineering soil and stone is huge, mainly from construction demolition, engineering construction, mine exploitation, industrial production and other links. At present, the comprehensive utilization rate of waste engineering soil and stone is less than 10%, and most of the engineering soil and stone are directly landfilled or stacked, which not only occupies a large amount of land resources, but also causes serious harm to the environment.

[0003] Geopolymer is a new type of inorganic polymer material formed by the alkali-activation reaction of aluminosilicate materials. Its main raw materials are usually industrial by-products rich in silicon and aluminum, such as fly ash, slag, metakaolin, etc. By reacting with alkaline activators (such as sodium hydroxide or sodium silicate), a cementitious material with a three-dimensional network structure is formed. The production process of geopolymers has low energy consumption and less carbon emissions. Its compressive strength, tensile strength and durability are usually better than those of ordinary concrete, especially outstanding in high-temperature environments, making it have broad application potential in the fields of construction, environmental protection and high-temperature materials.

[0004] At present, the technology for using engineering soil and stone is mainly to calcine the engineering soil and stone and then mix it with a liquid alkali activator and other additives to obtain an engineering soil and stone-based geopolymer. For example, the prior art discloses a preparation method of a geopolymer road base material, including the following steps: mixing calcined engineering soil and stone, uncalcined engineering soil and stone and an alkali activator according to a mass ratio of calcined engineering soil and stone, uncalcined engineering soil and stone and an alkali activator of 1:(0-4):(0.45-3.05), and carrying out a polymerization reaction to obtain a geopolymer road base material; the alkali activator includes water, sodium hydroxide and sodium silicate, and the 28-day compressive strength does not exceed 48.58 MPa. However, the compressive strength of the engineering soil and stone-based geopolymer prepared by the above method is not high enough. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a single-component alkali-activated engineering slag geopolymers and its preparation method and application. The single-component alkali-activated engineering slag geopolymers provided by the present invention has high compressive strength.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a single-component alkali-activated engineering slag geopolymers. Calculated by mass fraction, the preparation raw materials include: 100 parts of solid waste; 0-6 parts of alkali metal salt flux; calculated by sodium oxide, 3-6 parts of solid alkali activator; 30-35 parts of water;

[0008] In terms of mass percentage, the solid waste includes 50-70% of construction waste soil and 30-50% of slag.

[0009] The construction waste soil is calcined before use. When the calcination temperature ≤ 800 °C, the dosage of the alkali metal salt flux is not zero and it is mixed with the construction waste soil and then calcined.

[0010] Preferably, the alkali metal salt flux includes one or more of alkali metal sulfates, alkaline earth metal sulfates, alkali metal carbonates, and alkaline earth metal carbonates.

[0011] Preferably, the solid alkali activator includes Na2SiO3 and / or the calcined product, and the calcined product is the calcined product of Na2CO3 and SiO2.

[0012] Preferably, the particle size of the construction waste soil is ≥ 80 mesh.

[0013] Preferably, the particle size of the slag is 50-1000 nm.

[0014] The present invention also provides a preparation method of the single-component alkali-activated construction waste soil geopolymer described in the above technical solution, including the following steps:

[0015] Calcine the raw material to be calcined to obtain a calcined material; when the calcination temperature ≤ 800 °C, the raw material to be calcined is a mixture of construction waste soil and an alkali metal salt flux, and when the calcination temperature > 800 °C, the raw material to be calcined is construction waste soil, or a mixture of construction waste soil and an alkali metal salt flux;

[0016] Mix the calcined material, slag, solid alkali activator and water to obtain a geopolymer paste;

[0017] Form and cure the geopolymer paste to obtain a single-component alkali-activated construction waste soil geopolymer.

[0018] Preferably, the calcination temperature is 550-950 °C, and the heat preservation time is 100-150 min.

[0019] Preferably, the mixing includes: first mixing the calcined material, slag and solid alkali activator to obtain a dry material; second mixing the dry material and water; the rotation speed of the first mixing is 30-60 r / min, and the time is 1-2 min; the rotation speed of the second mixing is 100-150 r / min, and the time is 1-3 min.

[0020] Preferably, the forming temperature is 23-27 °C, the relative humidity is 92-98%, and the time is 23-25 h; the forming includes static forming;

[0021] The curing temperature is 23 to 27 °C, the relative humidity is 92 to 98%, and the time is 1 to 28 days.

[0022] The present invention also provides the application of the single-component alkali-activated engineering slag geopolymer described in the above technical solution or the single-component alkali-activated engineering slag geopolymer prepared by the preparation method described in the above technical solution as a building material.

[0023] The present invention calcines the engineering muck, which can improve its physical and chemical properties, convert the kaolin in the engineering muck into metakaolin with higher activity, change the structure of the engineering muck, improve its strength, hardness and durability, enable it to be better recycled, and thus improve the strength of the single-component alkali-activated engineering slag geopolymer. Moreover, calcination can also remove organic impurities and harmful substances (such as heavy metals) in the engineering muck, reducing environmental hazards.

[0024] The present invention calcines the engineering muck and an alkali metal salt flux together, incorporates slag and reacts with a solid alkali activator to generate a gel material. The present invention utilizes the alkali activator technology and controls the ratio of each raw material to obtain a single-component alkali-activated engineering slag geopolymer with excellent compressive strength, which has good market application prospects as a building material.

[0025] The alkali activator used in the present invention is solid. In the case of a relatively low dosage, the single-component alkali-activated engineering slag geopolymer has excellent compressive strength. Moreover, compared with the traditional water glass as an alkali activator, the present invention uses a solid alkali activator, which is easy to store, transport, has a simple operation process, and can more efficiently solve the problem of the utilization of waste engineering muck.

[0026] Engineering muck has certain activity under the action of solid alkali activator, and can act as a filler and alkali-activated gel material after adding solid alkali activator and slag. Compared with other mineral admixtures, slag, as a by-product in the steel production process, has a chemical composition more similar to that of ordinary cement. The glassy particles in slag are finer and have a higher content, enhancing the reactivity of the mixture, thus accelerating the polymerization process and effectively improving the mechanical properties of the single-component alkali-activated engineering muck geopolymers and reducing the setting time of geopolymers. The present invention utilizes a solid alkali activator to synergistically activate slag and engineering muck, realizing the efficient preparation of geopolymers. Specifically, under alkali activation conditions, slag rapidly releases silicon-aluminum monomers and calcium ions, promoting the formation of calcium silicate aluminate hydrate gel and providing strength support for the formation of the three-dimensional network structure of geopolymers. At the same time, engineering muck releases some active silicon-aluminum monomers under alkali activation, and the calcium ions dissolved from slag further activate the kaolin component in engineering muck, promoting the formation of sodium silicate aluminate hydrate gel. Although the single-component alkali-activated engineering muck geopolymers with too high slag content have poor volume stability and are prone to microcracks, the engineering muck particles react slowly in the early stage, can effectively fill pores, and alleviate the volume mismatch problem caused by the rapid reaction of slag, thereby enhancing the compressive strength of geopolymers.

[0027] Moreover, the present invention uses engineering muck and slag as the main raw materials, not only consuming a large amount of different types of solid wastes, but also saving a large amount of natural resources, achieving low-carbon emission reduction.

[0028] As shown by the test results of the examples, the 28-day compressive strength of the single-component alkali-activated engineering muck geopolymers provided by the present invention reaches up to 80.7 MPa, with high compressive strength.

[0029] The present invention also provides a preparation method of the single-component alkali-activated engineering muck geopolymers described in the above technical solution. The present invention calcines engineering muck and an alkali metal salt flux together, mixes in slag and then reacts with a solid alkali activator to generate a gel material. By using the alkali activator technology and controlling the ratio of each raw material, a single-component alkali-activated engineering muck geopolymer with excellent compressive strength is prepared. Moreover, the preparation method provided by the present invention has a simple process, is easy to operate, energy-saving and environmentally friendly, and is suitable for industrial production.

[0030] Engineering muck and the alkali metal flux are calcined together to produce Na2SiO3 and NaAlO2. Among them, Na2SiO3 can provide active silicon and directly act as an activator to promote gel formation; NaAlO2 can provide active aluminum to enhance the structural strength; Na2O or Na generated by partial decomposition of the metal flux + can increase the pH value of the system, promote the dissolution of silicon-aluminum minerals in engineering muck, and accelerate the geopolymerization reaction. Description of the Drawings

[0031] Figure 1 Photographs of the engineering muck after drying (left) and the sieved ground engineering muck (right);

[0032] Figure 2 Photograph of the calcined engineering muck in Example 1;

[0033] Figure 3 X-ray diffraction (XRD) pattern of the engineering muck in Example 1;

[0034] Figure 4 Scanning electron microscope (SEM) images of the engineering muck in Example 1. The left image has a magnification of 3000 times, and the right image has a magnification of 30000 times;

[0035] Figure 5 Flow chart for the preparation of the single-component alkali-activated engineering muck geopolymers of the present invention;

[0036] Figure 6 Photograph of the calcined material obtained by calcining the mixture of the engineering muck and the alkali metal flux in Example 3;

[0037] Figure 7 SEM images of the slag in Example 1. The left image has a magnification of 500 times, and the right image has a magnification of 1000 times;

[0038] Figure 8 Photograph of the single-component alkali-activated engineering muck geopolymer prepared in Comparative Example 8 during the compressive strength test;

[0039] Figure 9 X-ray photoelectron spectroscopy (XPS) spectra of C 1s, O 1s, Si 2p, and Al 2p of the single-component alkali-activated engineering muck geopolymers (3-day age) prepared in Examples 2 to 4;

[0040] Figure 10 Si NMR and 29 Si NMR and 27 Al NMR spectra of the single-component alkali-activated engineering muck geopolymers (28-day age) in Examples 1, 3, and 14;

[0041] Figure 11 Thermogravimetric infrared mass spectrometry (TIMA) graph of the single-component alkali-activated engineering muck geopolymer (28-day age) prepared in Example 1;

[0042] Figure 12 Thermogravimetric infrared mass spectrometry (TIMA) graph of the single-component alkali-activated engineering muck geopolymer (28-day age) with a curing age of 28 days prepared in Example 3;

[0043] Figure 13TIMA diagram of the single-component alkali-activated engineering slag geopolymer (28-day age) prepared in Example 28. Detailed implementation mode

[0044] The present invention provides a single-component alkali-activated engineering slag geopolymer. Calculated by mass parts, the preparation raw materials include: 100 parts of solid waste; 0-6 parts of alkali metal salt flux; calculated by sodium oxide, 3-6 parts of solid alkali activator; 30-35 parts of water.

[0045] Calculated by mass percentage, the solid waste includes 50-70% of engineering soil and 30-50% of slag.

[0046] The engineering soil is calcined before use. When the calcination temperature ≤ 800 °C, the dosage of the alkali metal salt flux is not 0 and it is mixed with the engineering soil and then calcined.

[0047] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0048] Calculated by mass parts, the preparation raw materials of the single-component alkali-activated engineering slag geopolymer provided by the present invention include 100 parts of solid waste. In the present invention, the solid waste includes engineering soil and slag.

[0049] In the present invention, by mass percentage, the solid waste includes 50-70% of construction waste soil, which can be 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68% or 70% in specific embodiments. In the present invention, the construction waste soil is preferably obtained by successively drying, pulverizing and sieving the construction waste soil mud cake. In the present invention, the drying temperature is preferably 60-90°C, which can be 60°C, 70°C, 80°C or 90°C in specific embodiments; the present invention has no special limitation on the drying time, and it can be dried to constant weight. In the present invention, the sieving is preferably through an 80-mesh standard sample sieve, and the undersize part is taken for use. In the present invention, the particle size of the construction waste soil is preferably ≥80 mesh. The present invention has no special limitation on the composition of the construction waste soil, and the construction waste soil well-known to those skilled in the art can be used. In the present invention, the construction waste soil is calcined before use. When the calcination temperature ≤800°C, the dosage of the alkali metal salt flux is not zero and it is mixed with the construction waste soil before calcination; when the calcination temperature >800°C, the dosage of the alkali metal salt flux can be zero or not zero. The construction waste soil has certain activity under the action of the solid alkali activator, and can play the role of filler and alkali-activated gel material after adding the solid alkali activator and slag, which can further improve the activity of the construction waste soil. The main purpose of calcining the construction waste soil is to improve its physical and chemical properties through high-temperature treatment, convert a large amount of kaolin in it into metakaolin with higher activity, so that it can be better reused. Calcination can remove organic impurities and harmful substances (such as heavy metals) in the construction waste soil, reducing environmental hazards; at the same time, high-temperature treatment can change the structure of the construction waste soil, improving its strength, hardness and durability.

[0050] In the present invention, some of the reaction equations that occur when the construction waste soil and the alkali metal flux are calcined together are as follows:

[0051] Na2SO4 only decomposes in a small part at high temperature (≤1100°C) to generate Na2O and SO3: Na2SO4→Na2O+SO3↑; the generated Na2O mainly reacts with SiO2 and AlO3 with relatively high contents in the construction waste soil to generate sodium silicate or sodium aluminate: Na2O+SiO2→Na2SiO3, Na2O+Al2O3→2NaAlO2; the main reaction can be comprehensively expressed as: construction waste soil (SiO2 / Al2O3)+Na2SO4→Na2SiO3+NaAlO2+SO3↑. Na2SO4 will also react with a small amount of components in the waste soil (such as Fe2O3, K2O) (secondary reaction): Na2SO4+Fe2O3→2NaFeO2+SO3↑, K2O+SO3→K2SO4, K2O+SiO2→K2SiO3.

[0052] Only a small part of Na2CO3 decomposes at high temperatures (≤1000 °C) to form Na2O and CO2: Na2CO3 → Na2O + CO2↑; Na2CO3 or Na2O mainly reacts with the relatively abundant SiO2 and AlO3 in engineering soil to form sodium silicate or sodium aluminate: Na2CO3 + SiO2 → Na2SiO3 + CO2↑, Na2O + SiO2 → Na2SiO3, Na2CO3 + Al2O3 → 2NaAlO2 + CO2↑, Na2O + Al2O3 → 2NaAlO2; The main reactions can be summarized as: Engineering soil (SiO2 / Al2O3) + Na2CO3 → Na2SiO3 + NaAlO2 + CO2↑. Na2CO3 also reacts with minor components in the soil (such as Fe2O3, K2O) (secondary reactions): Na2SO4 + Fe2O3 → 2NaFeO2 + CO2↑, K2O + CO2 → K2CO3, K2O + SiO2 → K2SiO3.

[0053] The Na2SiO3 produced by calcination can provide reactive silicon and directly act as an activator to promote gel formation; NaAlO2 can provide reactive aluminum to enhance the structural strength; Na2O or Na produced by partial decomposition of the metal flux + can increase the pH value of the system, promote the dissolution of silicon-aluminum minerals in engineering soil, and accelerate the geopolymerization reaction.

[0054] In the present invention, by mass percentage, the solid waste includes 30 - 50% slag, which can be 30%, 35%, 40%, 45% or 50% in specific embodiments. In the present invention, the particle size of the slag is preferably 50 - 1000 nm, which can be 50 nm, 100 nm, 200 nm, 500 nm, 800 nm or 1000 nm in specific embodiments. In the present invention, the slag preferably includes blast furnace slag, and the main chemical components of the slag preferably include: 38.40 - 40.84 wt% CaO, 29.69 - 31.61 wt% SiO2 and 15.91 - 17.86 wt% Al2O3; The strength grade of the slag is preferably S95; The density of the slag is preferably 2.2 - 2.8 g / cm 3 , which can be 2.2 g / cm 3 , 2.3 g / cm 3 , 2.4 g / cm 3 , 2.5 g / cm 3 , 2.6 g / cm 3 , 2.7 g / cm 3 or 2.8 g / cm 3。Slag, as a by-product in the steel production process, has chemical compositions more similar to those of ordinary cement. The glassy particles in slag are finer and have a higher content, enhancing the reactivity of the mixture, thus accelerating the polymerization process and effectively improving the mechanical properties of the single-component alkali-activated engineering slag geopolymers and reducing the setting time of geopolymers. Moreover, slag can partially replace cement, reducing carbon emissions and resource consumption and improving durability. Blast furnace slag can be used to refine pores and improve the long-term strength, sulfate resistance, and alkaline silica reactivity of concrete, as well as reduce the water demand, permeability, and heat generation during the hydration process.

[0055] Based on the mass parts of the solid waste, the preparation raw materials of the single-component alkali-activated engineering slag geopolymers provided by the present invention include 0-6 parts of alkali metal salt flux. In specific embodiments, it can be 0 part, 0.5 part, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, or 6 parts. In the present invention, the alkali metal salt flux preferably includes one or more of alkali metal sulfates, alkaline earth metal sulfates, alkali metal carbonates, and alkaline earth metal carbonates; alkali metal sulfates and / or alkali metal carbonates; the alkali metal sulfates preferably include sodium sulfate and / or potassium sulfate; the alkaline earth metal sulfates preferably include magnesium sulfate and calcium sulfate; the alkali metal carbonates preferably include sodium carbonate and / or potassium carbonate; the alkaline earth metal carbonates preferably include magnesium carbonate and calcium carbonate.

[0056] Based on the mass parts of the solid waste, the preparation raw materials of the single-component alkali-activated engineering slag geopolymers provided by the present invention include 3-6 parts of solid alkali activator (calculated by the amount of sodium oxide). In specific embodiments, it can be 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 6.5 parts, or 6 parts. In the present invention, the solid alkali activator preferably includes Na2SiO3 and / or calcined product, and the calcined product is the calcined product of Na2CO3 and SiO2. In an alkaline environment, the abundant CaO in slag dissolves to provide calcium ions, which is the key to the formation of C-S-H gel. Moreover, slag simultaneously provides highly reactive SiO2 and Al2O3; after the layered structure of the slag soil layer is destroyed, reactive SiO2 and Al2O3 are released, supplementing SiO2 and Al2O3 to increase the total amount of the gel system, and at the same time generating C-A-S-H gel to enhance the compactness; the fine particles (such as clay and silt) in the slag soil fill the voids between slag particles, improving the compactness. The C-S-H gel generated by alkali activation wraps the slag and slag soil particles, forming a three-dimensional network structure and enhancing the overall strength of the material.

[0057] In the present invention, the preparation method of the calcined product preferably comprises the following steps: mixing Na2CO3 and SiO2 and then performing calcination to obtain the calcined product. In the present invention, the molar ratio of Na2CO3 to SiO2 is preferably 1:1 to 2.5, and in specific embodiments, it can be 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.2 or 1:2.5. In the present invention, the calcination temperature is preferably 750 to 980 °C, and in specific embodiments, it can be 750 °C, 800 °C, 850 °C, 900 °C, 950 °C or 980 °C; the heat preservation time of the calcination is preferably 100 to 150 min, and in specific embodiments, it can be 100 min, 110 min, 120 min, 130 min, 140 min or 150 min; the heating rate of raising the temperature from room temperature to the calcination temperature is preferably 5 to 10 °C / min, and in specific embodiments, it can be 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min, 9 °C / min or 10 °C / min. After mixing Na2CO3 and SiO2 and then performing calcination, the present invention preferably further comprises: cooling the calcined system to room temperature to obtain the calcined product. The present invention has no special limitation on the cooling method, and any cooling method well known to those skilled in the art can be used.

[0058] In the present invention, the calcined product is preferably sodium silicate, or a mixture of sodium silicate and silicon dioxide. During the calcination of Na2CO3 and SiO2, Na2CO3 first decomposes to generate sodium oxide (Na2O) and carbon dioxide (CO2), and then sodium oxide reacts with silicon dioxide in a solid-phase reaction to generate sodium silicate (Na2SiO3). The chemical reaction equation for this process is: SiO2 + Na2CO 3→ Na2SiO3 + CO2↑.

[0059] Liquid water glass is prone to gelation or precipitation during storage, especially at low temperatures or during long-term storage, which will affect its use performance and increase the difficulty of storage and transportation. Moreover, water glass is prone to react with carbon dioxide in the air during use to generate sodium carbonate, resulting in the appearance of white crystals on the surface, that is, the "efflorescence" phenomenon, which not only affects the appearance but may also reduce the performance of geopolymers. The present invention uses a solid alkali activator, which is easy to store, transport, and has a simple operation process, and can more efficiently solve the problem of the utilization of waste engineering soil.

[0060] In the present invention, the changes in the contents of SiO2 and Na2O in the solid base activator have a significant impact on the alkali activation effect of the single-component alkali-activated engineering slag geopolymer. The silicate radical and the aluminosilicate radical generated by activating the engineering slag and soil undergo an adsorption effect on the surface of the slag particles, fill the ends of the crystals, and undergo a polycondensation reaction in an alkaline environment to form a massive dense structure, thereby improving the strength and durability of the single-component alkali-activated engineering slag geopolymer. The solid base activator can promote the dissolution of silicon and aluminum elements in the aluminosilicate raw materials and gradually polymerize to form the main products of the single-component alkali-activated engineering slag geopolymer, such as calcium aluminosilicate hydrate and sodium aluminosilicate hydrate. The present invention uses a solid base activator with a low dosage. When used in combination with other raw materials, the single-component alkali-activated engineering slag geopolymer has excellent compressive strength.

[0061] Based on the mass parts of the solid waste, the preparation raw materials of the single-component alkali-activated engineering slag geopolymer provided by the present invention include 30 - 35 parts of water (i.e., the water-solid ratio is 0.3 - 0.35). In specific embodiments, it can be 30 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, or 35 parts. Water mainly serves as a reaction medium during the preparation of the geopolymer and participates in the dissolution and gel formation processes of the geopolymer raw materials. However, all the water is discharged after the reaction ends, and the geopolymer finally forms an anhydrous or less-water three-dimensional network structure. The water-solid ratio of the preparation raw materials of the single-component alkali-activated engineering slag geopolymer provided by the present invention can be as low as 0.3. Due to the reduction in the added amount of external water, the pores formed after the material dries out are relatively small, which is beneficial to improving the compressive strength of the single-component alkali-activated engineering slag geopolymer.

[0062] In the present invention, the 3-day (age of 3d) compressive strength of the single-component alkali-activated engineering slag geopolymer is preferably > 21 MPa, more preferably 21.5 - 65.0 MPa. In specific embodiments, it can be 21.5 MPa, 37.6 MPa, 38.3 MPa, 38.6 MPa, 41.3 MPa, 42.3 MPa, 43.9 MPa, 44.5 MPa, 45.7 MPa, 46.6 MPa, 48.6 MPa, 49.0 MPa, or 65.0 MPa.

[0063] In the present invention, the 7-day (age of 7d) compressive strength of the single-component alkali-activated engineering slag geopolymer is preferably > 41 MPa, more preferably 41.2 - 71.8 MPa. In specific embodiments, it can be 41.2 MPa, 44.7 MPa, 45.4 MPa, 50.4 MPa, 52.2 MPa, 53.0 MPa, 55.0 MPa, 55.5 MPa, 56.6 MPa, 58.8 MPa, 59.3 MPa, 69.5 MPa, 71.8 MPa.

[0064] In the present invention, the 28-day (age of 28 days) compressive strength of the single-component alkali-activated engineering slag geopolymer is preferably > 51.5 MPa, more preferably 51.8 - 80.7 MPa, and in specific embodiments, it can be 51.8 MPa, 56.3 MPa, 58.2 MPa, 59.5 MPa, 60.5 MPa, 61.6 MPa, 63.2 MPa, 64.9 MPa, 65.3 MPa, 66.2 MPa, 71.5 MPa, 76.1 MPa, 76.9 MPa or 80.7 MPa.

[0065] The present invention also provides a preparation method of the single-component alkali-activated engineering slag geopolymer described in the above technical solution, including the following steps:

[0066] Calcine the raw material to be calcined to obtain a calcined material; when the calcination temperature ≤ 800 °C, the raw material to be calcined is a mixture of engineering soil and alkali metal salt flux, and when the calcination temperature > 800 °C, the raw material to be calcined is engineering soil, or a mixture of engineering soil and alkali metal salt flux;

[0067] Mix the calcined material, slag, solid alkali activator and water to obtain geopolymer paste;

[0068] Form and cure the geopolymer paste to obtain the single-component alkali-activated engineering slag geopolymer.

[0069] In the present invention, the raw material to be calcined is calcined to obtain a calcined material; when the calcination temperature ≤ 800 °C, the raw material to be calcined is a mixture of engineering soil and alkali metal salt flux, and when the calcination temperature > 800 °C, the raw material to be calcined is engineering soil, or a mixture of engineering soil and alkali metal salt flux.

[0070] In the present invention, the calcination temperature is preferably 550 - 950 °C, and in specific embodiments, it can be 550 °C, 600 °C, 650 °C, 700 °C, 750 °C, 800 °C, 850 °C, 900 °C or 950 °C; the heating rate of the temperature rising from room temperature to the calcination temperature is preferably 4 - 7 °C / min, and in specific embodiments, it can be 4 °C / min, 5 °C / min, 6 °C / min or 7 °C / min; the calcination holding time is preferably 2 h; the calcination is preferably carried out in a muffle furnace.

[0071] When engineering muck is calcined together with alkali metal carbonate, silicate minerals (such as kaolin, quartz, etc.) in the engineering muck will undergo high-temperature solid-phase reactions with alkali metal carbonate to generate compounds such as sodium silicate (Na2SiO2) and sodium aluminate (NaAlO2), and release carbon dioxide (CO2). Sodium oxide further reacts with silicon dioxide (SiO2) and aluminum oxide (Al2O2) in the engineering muck to form sodium silicate and sodium aluminate. This process can not only activate the inert components in the engineering muck and convert them into substances with higher activity, but also improve the physical and chemical properties of the engineering muck, making it more suitable as building materials or industrial raw materials. In addition, organic impurities and harmful substances will be decomposed or volatilized during the calcination process, thereby reducing the environmental harmfulness of the engineering muck. Sulfur trioxide (SO2) generated by the decomposition of alkali metal sulfate may react with alkaline components (such as calcium oxide CaO) in the engineering muck to form calcium sulfate (CaSO4). This process can not only activate the inert components in the engineering muck and improve its physical and chemical properties, but also may introduce sulfate minerals, affecting the subsequent utilization performance of the engineering muck. During the calcination process, organic impurities and harmful substances in the engineering muck will also be decomposed or volatilized, thereby reducing the environmental harmfulness.

[0072] After completing the calcination, the present invention preferably further includes cooling the calcined system to room temperature to obtain a calcined material. In the present invention, the cooling preferably includes natural cooling.

[0073] After obtaining the calcined material, the present invention mixes the calcined material, slag, solid alkali activator and water to obtain geopolymer paste.

[0074] In the present invention, mixing the calcined material, slag, solid alkali activator and water preferably includes: first mixing the calcined material, slag and solid alkali activator to obtain a dry material; and second mixing the dry material and water. In the present invention, the rotation speed of the first mixing is preferably 30-60 r / min, and in specific embodiments, it can be 30 r / min, 35 r / min, 40 r / min, 45 r / min, 50 r / min, 55 r / min or 60 r / min; the time of the first mixing is preferably 1-2 min, and in specific embodiments, it can be 1 min, 1.5 min or 2 min. In the present invention, the rotation speed of the second mixing is 100-150 r / min, and in specific embodiments, it can be 100 r / min, 110 r / min, 120 r / min, 130 r / min, 140 r / min or 150 r / min; the time of the second mixing is preferably 1-3 min, and in specific embodiments, it can be 1 min, 1.5 min, 2 min, 2.5 min or 3 min. By adopting the above mixing method, the present invention can improve the dispersibility and hydration reaction of the dry material, and further enhance the uniformity, chemical stability (corrosion resistance, carbonation resistance, etc.), physical stability (volume stability, impermeability, etc.), thermal stability and durability of the material.

[0075] After obtaining the geopolymer paste, the present invention forms and cures the geopolymer paste to obtain a single-component alkali-activated engineering slag geopolymer.

[0076] In the present invention, the forming is preferably carried out in a mold. Specifically, the geopolymer paste is injected into the mold layer by layer, vibrated and compacted, sealed, demolded after forming, and a single-component alkali-activated engineering slag geopolymer gel is obtained.

[0077] The present invention has no special limitation on the material and size of the mold, and it can be determined according to actual needs. In the present invention, the mold is preferably cleaned, taped on the contact surface, and a release agent is applied on the mold wall before use to facilitate the demolding of the single-component alkali-activated engineering slag geopolymer. The present invention has no special limitation on the release agent, and a release agent well-known to those skilled in the art can be used.

[0078] The present invention preferably places the mold on a vibrating table first, then injects the geopolymer slurry into the mold, vibrates it, and then vibrates and compacts it until the surface of the geopolymer paste in the mold is smooth.

[0079] In the present invention, the sealing is preferably sealing with plastic wrap. By sealing, the present invention can prevent the alkaline surface of the geopolymer paste and the single-component alkali-activated engineering slag geopolymer from reacting with CO2 in the air to form carbonates and carbonation; at the same time, it can also prevent cracks caused by surface drying shrinkage due to water evaporation.

[0080] In the present invention, the temperature for shaping is preferably 23 to 27 °C, and in specific embodiments, it can be 23 °C, 24 °C, 25 °C, 26 °C or 27 °C; the relative humidity for shaping is preferably 92 to 98%, and in specific embodiments, it can be 92%, 93%, 94%, 95%, 96%, 97% or 98%; the time for shaping is preferably 23 to 25 h, and in specific embodiments, it can be 23 h, 23.5 h, 24 h, 24.5 h or 25 h; the shaping is preferably static shaping; the shaping is preferably carried out in a constant temperature and humidity curing box.

[0081] In the present invention, the temperature for curing is preferably 23 to 27 °C, and in specific embodiments, it can be 23 °C, 24 °C, 25 °C, 26 °C or 27 °C; the relative humidity for curing is preferably 92 to 98%, and in specific embodiments, it can be 92%, 93%, 94%, 95%, 96%, 97% or 98%; the time for curing is preferably 1 to 28 days, and in specific embodiments, it can be 1 day, 2 days, 4 days, 6 days, 10 days, 12 days, 15 days, 20 days, 22 days, 25 days, 27 days or 28 days; the curing is preferably carried out in a constant temperature and humidity curing box.

[0082] The present invention also provides the application of the single-component alkali-activated engineering slag geopolymer described in the above technical solution or the single-component alkali-activated engineering slag geopolymer prepared by the preparation method described in the above technical solution as a building material.

[0083] The present invention uses engineering soil and slag as the main raw materials, utilizes alkali activation technology and controls the ratio of each raw material. Under the condition of less dosage of alkali activator, a high-strength single-component alkali-activated engineering slag geopolymer is obtained. The present invention can obtain a high-strength single-component alkali-activated engineering slag geopolymer without adding external reinforcing agents (such as fibers). The single-component alkali-activated engineering slag geopolymer provided by the present invention has good application prospects as a building material. Moreover, the present invention uses engineering soil and slag as the main raw materials, on the one hand, consumes a large amount of different types of solid wastes, and on the other hand, saves a large amount of natural resources and realizes low-carbon emission reduction.

[0084] In order to further illustrate the present invention, the following examples are used to describe in detail the single-component alkali-activated engineering slag geopolymer provided by the present invention, its preparation method and application, but they should not be construed as limiting the protection scope of the present invention.

[0085] In the following examples and comparative examples, the engineering soil mud cake comes from the working site of underground engineering excavation, according to Figure 5As shown in the flow chart, the construction waste soil cake is dried at 60°C, ground with a grinder, passed through a standard sample sieve of 80 mesh, and the construction waste soil under the sieve is directly put into a muffle furnace for calcination to obtain calcined construction waste soil. Figure 1 The following are the actual pictures of the construction waste soil after drying (left) and the construction waste soil after grinding and sieving (right). Figure 2 This is a real picture of calcined engineering slag. Figures 1 - 2 It can be seen that after calcination, the color of the engineering slag changes from earth yellow to light brown, and the particles are more dispersed. Figure 3 ,Depend on Figure 3 It can be seen that the construction waste soil mainly contains quartz, kaolinite and illite. Figure 4 , where the left picture is magnified 3000 times, and the right picture is magnified 30000 times. Figure 4 It can be seen that the surface morphology of construction waste particles is relatively rough, mainly stacked with flake structures, and there are irregular microscopic gaps and protrusions between the particles. At the same time, it can be observed that the sample has a large number of agglomerates, and there are particles surrounding it. A large number of agglomerates are arranged in a non-directional manner. The agglomerates are mainly generated in the form of edge-face and face-face, with relatively loose contact, and the outer particles also have no obvious directional distribution pattern.

[0086] according to Figure 5 The flow chart shown in the figure is as follows: the engineering slag under the sieve is mixed with an alkali metal salt flux and then placed in a muffle furnace for calcination to obtain a calcined material. The calcined material obtained in Example 3 is as follows: Figure 6 As shown by Figure 6 It can be seen that the engineering slag and alkali metal flux are calcined together to form a dense block. Figure 7 , where the left picture is magnified 500 times, and the right picture is magnified 1000 times. Figure 7 It can be seen that the surface morphology of the slag raw material is flat, it is block-shaped particles, and it is an amorphous glass body.

[0087] The particle size of the engineering slag after screening is less than 10 μm. The main chemical components obtained by XRF analysis are shown in Table 1.

[0088] Table 1 Main chemical components of engineering slag (wt%)

[0089] Component <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> <![CDATA[K2O]]> MgO CaO <![CDATA[TiO2]]> <![CDATA[Na2O]]> <![CDATA[SO3]]> Cl <![CDATA[P2O5]]> MnO Content 56.65 33.15 3.35 2.71 1.52 0.94 0.50 0.46 0.24 0.18 0.09 0.03

[0090] The slag is selected from Guangdong Shaoguan Iron and Steel Company, with a strength grade of S95 and a density of 2.5g / cm 3 The quality meets the requirements of GB / T18046-2008, and the particle size is 50-1000nm; the main chemical components of the slag obtained by XRF analysis are shown in Table 2.

[0091] Table 2 Main chemical composition of slag (wt%)

[0092] Component <![CDATA[SiO2]]> CaO <![CDATA[Al2O3]]> MgO <![CDATA[K2O]]> <![CDATA[Na2O]]> <![CDATA[Fe2O3]]> <![CDATA[SO3]]> <![CDATA[TiO2]]> MnO Content 30.61 39.84 16.91 9.06 0.28 0.29 0.22 1.59 0.69 0.26

[0093] Sodium silicate: modulus is 2.0, density is 1.44 g / cm 3 , the alkali content of sodium silicate = mass of Na2O in sodium silicate / (mass of engineering soil residue + mass of mineral powder) × 100%.

[0094] Preparation of calcined product (denoted as product A): Mix Na2CO3 and SiO2 evenly according to a molar ratio of 1:1.5, heat up to 800 °C at a rate of 5 °C / min, keep it for calcination for 2 h, and then cool it to room temperature.

[0095] Engineering soil residue incorporation ratio = mass of engineering soil residue / (mass of engineering soil residue + mass of slag) × 100%.

[0096] Water-solid ratio = mass of added water / (mass of engineering soil residue + mass of slag).

[0097] Alkali dosage of alkali metal salt flux = mass of Na2O in alkali metal salt flux / (mass of engineering soil residue + mass of slag) × 100%.

[0098] Alkali dosage of alkali activator = mass of Na2O in alkali activator / (mass of engineering soil residue + mass of slag) × 100%.

[0099] Compressive strength test method: According to the GB / T17671-1999 standard, the dimensions of the engineering soil residue-based geopolymer specimens for compressive test are all 40 mm × 40 mm × 40 mm, the loading speed is 2.4 kN / s, and the testing machine used is the Wuxi Zhongke Building Materials Strength Testing Machine; in order to ensure the accuracy of the results, the average value of three parallel tests is taken as the final data result.

[0100] Examples 1 - 15 and Comparative Examples 1 - 13

[0101] The raw material dosages of Examples 1 - 15 and Comparative Examples 1 - 13 are shown in Table 3. According to the Figure 5 flow chart shown, the preparation method of single-component alkali-activated engineering soil residue-based geopolymer is as follows: Crush the engineering soil residue with a crusher, pass it through a standard sample sieve with 80 meshes, dry the undersize part in an oven at 80 °C, put the dried engineering soil residue and alkali metal salt flux into a muffle furnace, heat up to the calcination temperature (shown in Table 3) at a rate of 5 °C / min, keep it for 2 h, and then cool it naturally to room temperature to obtain the calcined material. Among them, in Examples 1 - 2, Examples 7 - 11, Comparative Examples 6 - 8, and Comparative Example 11, no alkali metal salt flux is added.

[0102] Stir the calcined material, slag and alkali activator at a low speed of 60 r / min for 2 min, then add water and stir at a high speed of 120 r / min for 3 min to obtain geopolymer paste.

[0103] Layer the geopolymer paste into a 40 mm×40 mm×40 mm cube triple mold and a 40 mm×40 mm×160 mm cuboid triple mold placed on a vibrating table. While injecting the slurry, vibrate and compact it until the surface of the sample in the mold is flat and smooth. Seal it with plastic wrap and place it in a constant temperature and humidity curing box at 25±2°C and a relative humidity of 95% for static molding for 24 h and then demold to obtain the engineered soil residue-based geopolymer gel (specimen). Cure the engineered soil residue-based geopolymer gel in the above constant temperature and humidity box for 2 d, 6 d and 27 d respectively to obtain single-component alkali-activated engineered soil residue geopolymers with different ages (3 d, 7 d and 28 d). Among them, before using the cube triple mold and the cuboid triple mold, stick tape on the contact surface and apply a mold release agent on the mold wall for easy demolding.

[0104] Table 3 Preparation raw materials and compressive strength test results of single-component alkali-activated engineered soil residue geopolymers in examples and comparative examples

[0105]

[0106]

[0107] Note: "-" indicates that the strength cannot be measured due to too low strength.

[0108] Figure 8 Figure 19 is a physical diagram of the single-component alkali-activated engineered soil residue geopolymer prepared in Comparative Example 8 during the test of compressive strength. It can be seen that when sodium silicate is used as the activator, the strength of the test block is too low and it is directly crushed, and the strength cannot be measured.

[0109] As can be seen from Table 3, when the calcination temperature is 950°C, with other parameters being the same and only the alkali activator being different, the compressive strength of the single-component alkali-activated engineered soil residue geopolymer using a solid alkali activator is higher than that of the single-component alkali-activated engineered soil residue geopolymer using liquid sodium silicate. And when the incorporation ratio of engineered soil residue is 80%, the obtained compressive strength is relatively small. When the incorporation ratio of engineered soil residue is 70%, the 28-day compressive strength reaches 53.2 MPa. This content can not only maintain a very high compressive strength but also achieve the purpose of consuming a large amount of engineered soil residue.

[0110] When the calcination temperature is 800°C, adding a flux during the calcination of engineered soil residue can obtain test blocks with a 28-day strength as high as 64.9 MPa; even if no flux is added during the calcination of engineered soil residue, the compressive strength of the specimen using a solid alkali activator is still higher than that of the specimen using liquid sodium silicate, and the total alkali dosage is only 6%.

[0111] When the calcination temperature is 750 °C, although the calcination temperature is lower than 800 °C, due to the addition of a flux during the calcination of construction waste soil, specimens with a 28-day strength as high as 56.3 MPa can still be obtained when using a solid alkali activator; even when no flux is added during the calcination of construction waste soil, the compressive strength of the specimens using a solid alkali activator is still higher than 10 MPa, and the total alkali dosage is only 6%.

[0112] When the calcination temperature is 550 °C, this calcination temperature is much lower than 800 °C, but due to the addition of a flux during the calcination of construction waste soil, specimens with a 28-day strength as high as 49.8 MPa can still be obtained when using a solid alkali activator, and the total alkali dosage is only 6%.

[0113] From the above examples and comparative examples, it can be seen that the present invention uses construction waste soil and slag as geopolymer materials, and by controlling the content of construction waste soil, alkali content, water-solid ratio, etc., a geopolymer with considerable compressive strength has been successfully developed. While fully consuming construction waste soil, it can also reduce CO2 emissions, lower costs, and save resources.

[0114] The present invention uses a solid alkali activator to synergistically activate slag and construction waste soil, realizing the efficient preparation of geopolymer. Under alkali activation conditions, slag rapidly releases silicon-aluminum monomers and calcium ions, promoting the formation of calcium silicate aluminate hydrate gel, providing strength support for the formation of the three-dimensional network structure of the geopolymer. At the same time, construction waste soil releases some active silicon-aluminum monomers under the action of alkali activation, and the calcium ions dissolved from slag further activate the kaolin component in construction waste soil, promoting the formation of sodium silicate aluminate hydrate gel. Although the volume stability of the single-component alkali-activated construction waste soil geopolymer with too high slag content is poor and microcracks are prone to occur, the reaction rate of construction waste soil particles is slow in the early stage, which can effectively fill pores and relieve the volume mismatch problem caused by the rapid reaction of slag, thereby enhancing the compressive strength of the geopolymer. In an alkaline environment, even when only 20% of slag and 80% of construction waste soil are added, the compressive strength of the single-component alkali-activated construction waste soil geopolymer can reach 16.60 MPa at 28 days, demonstrating excellent mechanical properties and resource utilization value.

[0115] Figure 9 Electron energy spectra of C 1s, O 1s, Si 2p, and Al 2p for the single-component alkali-activated construction waste soil geopolymer (3-day age) prepared in Examples 2-4. The analysis of the C 1s spectrum shows that all samples exhibit a C-C characteristic peak at 284.80 eV; while the binding energy of the C-O-C bond varies significantly due to different ratios: 0C3N (286.19 eV) shows a typical ether bond, the binding energy of 3A3N (287.58 eV) increases, and the binding energy of 3A3M (285.36 eV) decreases; in addition, all samples exhibit CO3 at approximately 289.3 eV 2-Or carboxyl peaks indicate the presence of oxidation products on the surface. The analysis of the O 1s spectrum shows that the sample prepared in Example 2 is mainly composed of carbonate and C-O bonds, while the binding energy of the C-O bond in the samples prepared in Examples 3-4 decreases, and alumina is formed in the sample prepared in Example 3. The analysis of the Si 2p spectrum shows that the sample prepared in Example 2 is mainly composed of SiO2 and SO4 2- indicating that there is more residual SiO2 in the sample and the reaction is not complete. Due to the relatively complete reaction in the samples prepared in Examples 3-4, an aluminosilicate (Al-O-Si) structure is formed, resulting in a decrease in the Si 2p binding energy. SO4 2- peaks stably exist in all three samples. These results, together with the C1s and O1s data, indicate that aluminum doping significantly changes the silicon-oxygen network structure of the material. The analysis of the Al 2p spectrum shows that aluminum in the sample prepared in Example 2 exists as a mixed phase of aluminosilicate and alumina, indicating that aluminum is not completely incorporated into the silicon-oxygen network. The aluminosilicate peak dominates in the samples prepared in Examples 3-4, and the alumina peak weakens, indicating that nitrogen or metal doping optimizes the integration of aluminum to form a more stable Al-O-Si structure. Combining the Si 2p and O1s data, it can be inferred that the formation of aluminosilicate increases and the free alumina decreases. These results are consistent with the Si 2p and O1s data analyzed previously, jointly revealing the synergistic regulation effect of doping on the material structure.

[0116] Figure 10 For the single-component alkali-activated slag geopolymers (28-day age) of Examples 1, 3, and 14 29 Si NMR and 27 Al NMR spectra.

[0117] For the single-component alkali-activated slag geopolymer prepared in Example 1 29 the Si spectral peaks are concentrated in the range of -90 to -110 ppm, where the main peak near -100 ppm corresponds to the highly polymerized Q 4 (SiO4) structure, indicating that silicon is mainly tetrahedrally coordinated bridging oxygen to form a dense silicon-oxygen network; while the shoulder peak near -90 ppm may originate from Q 3 (SiO3(OH)) structure, indicating the presence of a small amount of silanol groups or terminal defects. The spectral characteristics are similar to those of undoped pure silica or silicate glass, indicating a relatively high integrity of the silicon-oxygen network.

[0118] For Example 3 29 the Si spectral peaks as a whole shift towards the high-field direction (such as -80 to -100 ppm), the intensity of the Q 4 peak weakens, and at the same time, a new signal appears near -80 ppm, which can be attributed to Q 2 (SiO2(OH)2) or Al-O-Si structure. This change indicates a decrease in the degree of polymerization of the silicon-oxygen network, which may be due to aluminum doping (Al3+ Substituted Si 4+ ) causes the breakage of silicon-oxygen bonds, forming more non-bridging oxygen or aluminosilicate units. In addition, the shift of the chemical shift also indicates an increase in the electron density around silicon, which may be related to nitrogen doping (such as Si-N bonds) or local charge compensation effects.

[0119] For the single-component alkali-activated engineered slag geopolymers prepared in Example 14 29 The Si spectrum is relatively complex, and the peak position is further broadened to -70 to -120 ppm. In addition to the silicon-oxygen peaks of Q 4 / Q 3 / Q 2 In addition to the silicon-oxygen peaks of Q

[0120] Generally speaking, from Example 1 → 3 → 14, the coordination state of silicon gradually changes from the highly polymerized Q 4 structure to a lower degree of polymerization (Q 3 / Q 2 ) or heteroatom bonding (Si-N, Si-O-M). This evolution may be closely related to the co-doping of aluminum / nitrogen, the introduction of metals, or the difference in synthesis temperature, resulting in the evolution of the silicon-oxygen network from a rigid to a more open chemical structure.

[0121] For the single-component alkali-activated engineered slag geopolymers prepared in Example 1 27 The Al spectrum shows a sharp and symmetric peak at 60 ppm, indicating that aluminum is regularly incorporated into the silicon-oxygen network in the form of a single four-coordinated [AlO4], forming a relatively well-crystallized aluminosilicate structure.

[0122] For the single-component alkali-activated engineered slag geopolymers prepared in Example 3 27 The Al spectrum shows obvious spectral changes: the [AlO4] peak at 60 ppm is significantly broadened, and at the same time, five-coordinated [AlO5] and six-coordinated [AlO6] characteristic peaks appear in the regions of 30 ppm and 0 - 10 ppm respectively. This coexistence state of multiple coordinations may be due to the coordination field distortion caused by nitrogen doping or the increase in the coordination number caused by special heat treatment conditions.

[0123] For the single-component alkali-activated engineered slag geopolymers prepared in Example 14 27The spectrum of the Al spectrum becomes more complicated. Not only does the [AlO4] peak continue to broaden, the [AlO5] and [AlO6] peak intensities are significantly enhanced, and weak signals appear at -10 to -20 ppm, suggesting the possible existence of aluminum species with special coordination environments. This transition from a single four-coordinate state to a multi-coordinate mixed state ([AlO4]→[AlO4]+[AlO5]+[AlO6]) reflects the profound influence of preparation conditions on the local structure of aluminum: the introduction of doping elements (such as nitrogen) will destroy the original coordination symmetry, while high-temperature treatment may promote the formation of high-coordination aluminum. This diversity of coordination states will directly affect the acid site distribution, structural stability, and catalytic performance of the material, which is consistent with previous 29 Si NMR shows the depolymerization of silicon-oxygen network (Q 4 →Q 3 / Q 2 ) confirm each other and jointly reveal the structure-activity relationship of doping-structure-performance.

[0124] TIMA (Tescan Integrated Mineral Analyzer) comprehensive mineral analysis system is a fully automated quantitative mineral analysis system based on a scanning electron microscope. It identifies mineral phases by combining BSE and EDS signals, and then uses TIMA analysis software to segment mineral phases to obtain basic rock and mineral information such as mineral type and content, distribution, particle size, dissociation degree, and element content and occurrence. TIMA tests were performed on the single-component alkali-activated engineering slag land polymers prepared in Examples 1, 3 and 28 with a curing age of 28 days. The results are shown in Table 1. Figure 11 , Figure 12 , Figure 13 And Table 4, Figures 11 - 13 The legend for the middle figure in the first row is at the bottom.

[0125] Table 4 TIMA results of single-component alkali-activated engineering slag geopolymers prepared in Examples 1, 3 and 28 with a curing age of 28 days

[0126]

[0127] Depend on Figures 11 - 13 As shown in Table 4, in Examples 3 and 14, since Na2SO4 is added during calcination, it will react with a small amount of CaO in the slag to form calcium aluminosilicate, while in Example 1, no Na2SO4 is added during calcination, and less calcium aluminosilicate is produced; in Example 3, since the calcination temperature is higher (950°C), more Na2SO4 is decomposed, and more Na2O or Na +, thus more sodium potassium aluminosilicate and albite are produced; in Example 3, due to the relatively high calcination temperature and the addition of Na2SO4 during calcination, more and more sufficient reactions occur with the construction waste soil, so the mass of the matrix in the reaction product is the least, and since the construction waste soil contains a certain amount of quartz, the content of the remaining unreacted quartz in Example 3 is the least.

[0128] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A single-component alkali-activated engineered slag geopolymer, characterized in that, On a mass parts basis, the preparation raw materials include: 100 parts of solid waste; 0 - 6 parts of alkali metal salt flux; 3 - 6 parts of solid base activator calculated as sodium oxide; 30 - 35 parts of water; On a mass percentage basis, the solid waste includes 50 - 70% of engineering muck and 30 - 50% of slag; The engineering muck is calcined before use. When the calcination temperature ≤ 800°C, the dosage of the alkali metal salt flux is not 0 and it is mixed with the engineering muck and then calcined.

2. The single-component alkali-activated engineered slag geopolymer according to claim 1, wherein The alkali metal salt flux includes one or more of alkali metal sulfates, alkaline earth metal sulfates, alkali metal carbonates, and alkaline earth metal carbonates.

3. The single-component alkali-activated engineered slag geopolymer according to claim 1, wherein The solid base activator includes Na2SiO3 and / or the calcined product, and the calcined product is the calcined product of Na2CO3 and SiO2.

4. The single-component alkali-activated engineered slag geopolymer according to claim 1, wherein The particle size of the engineering muck is ≥ 80 mesh.

5. The single-component alkali-activated engineered slag geopolymer according to claim 1, wherein The particle size of the slag is 50 - 1000 nm.

6. The preparation method of the single-component alkali-activated engineering slag geopolymer according to any one of claims 1 to 5, characterized in that, It includes the following steps: Calcine the raw materials to be calcined to obtain the calcined material; when the calcination temperature ≤ 800°C, the raw materials to be calcined are the mixture of engineering muck and alkali metal salt flux, and when the calcination temperature > 800°C, the raw materials to be calcined are the engineering muck, or the mixture of engineering muck and alkali metal salt flux; Mix the calcined material, slag, solid base activator, and water to obtain geopolymer paste; Form and cure the geopolymer paste to obtain a single - component alkali - activated engineering muck - based geopolymer.

7. The preparation method according to claim 6, characterized in that, The calcination temperature is 550 - 950°C, and the heat - preservation time is 100 - 150 min.

8. The preparation method according to claim 6, characterized in that, The mixing includes: first mixing the calcined material, slag, and solid base activator to obtain a dry material; second - mixing the dry material and water; the rotation speed of the first mixing is 30 - 60 r / min, and the time is 1 - 2 min; the rotation speed of the second mixing is 100 - 150 r / min, and the time is 1 - 3 min.

9. The preparation method according to claim 6, characterized in that, The forming temperature is 23 - 27°C, the relative humidity is 92 - 98%, and the time is 23 - 25 h; the forming is static forming; The curing temperature is 23 - 27°C, the relative humidity is 92 - 98%, and the time is 1 - 28 days.

10. The application of the single - component alkali - activated engineering muck - based geopolymer according to any one of claims 1 - 5 or the single - component alkali - activated engineering muck - based geopolymer prepared by the preparation method according to any one of claims 6 - 9 as a building material.

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