CN108046669B

CN108046669B - Geopolymer and preparation method and application thereof

Info

Publication number: CN108046669B
Application number: CN201711382031.8A
Authority: CN
Inventors: 阳栋; 谭立新; 李水生; 支华龙; 习智琴
Original assignee: China Construction Fifth Engineering Bureau Co Ltd
Current assignee: China Construction Fifth Engineering Bureau Co Ltd
Priority date: 2017-12-19
Filing date: 2017-12-19
Publication date: 2020-10-27
Anticipated expiration: 2037-12-19
Also published as: CN108046669A

Abstract

The invention discloses a geopolymer and a preparation method and application thereof, wherein the geopolymer is prepared by taking fly ash, shield muck and an alkaline activator as raw materials, the main component of the shield muck is clay, and the mass ratio of the fly ash to the dried shield muck is 1-2: 3; the mass ratio of the mixture of the fly ash and the dried shield muck to the alkaline activator is 1: 0.14-0.18. The geopolymer carries out resource utilization on the shield muck with high mud content, the preparation raw materials do not comprise any type of traditional cementing materials such as cement, lime and the like, the large carbon emission is avoided, and the cost is low; the geopolymer has high strength and good water resistance. According to the preparation method of the geopolymer, the alkaline activator is added into the mixture of the fly ash and the shield muck in a spraying manner, so that large aggregates are avoided; and the mixed wet material is compacted in a die so that the geopolymer test piece has higher strength and water resistance.

Description

Geopolymer and preparation method and application thereof

Technical Field

The invention relates to the technical field of recycling of muck, in particular to a geopolymer. In addition, the invention also relates to a preparation method and application of the geopolymer.

Background

The geopolymer is a novel green building material and can be prepared by reacting solid waste, minerals rich in silicon-aluminum components and alkali solution or alkali metal silicate solution, in particular to waste or minerals such as metakaolin, fly ash or slag. At present, 75% of electricity in China is supplied by thermal power stations, coal of the thermal power stations generates a large amount of fly ash, and the fly ash discharged by the power stations is increased sharply along with the increase of electricity consumption. The fly ash has wide source and low cost, and certain performance is superior to metakaolin, so the application of the fly ash to prepare the geopolymer has wide development prospect.

Along with the development of urban development and construction, particularly the high-speed development of subway construction in recent years, a large amount of building muck is generated, and the discharge and disposal of the muck become a great problem which puzzles urban environmental management. The shield machine tunneling is a construction method commonly adopted in the domestic subway excavation, and the generated shield muck has high water content and great harmfulness. Generally, the shield muck is a soil-rock mixture composed of crushed stone, sand, clay and water, and the content of each component of the shield muck is mainly influenced by the characteristics of the original stratum. For example, when the shield tunneling machine tunnels in various slightly weathered rock formations, the main components of the slag soil are broken stones and stone powder, the screening and the dehydration are easy, and the resources can be recycled through simple treatment; when the silty sand layer and the weathered sandstone are tunneled, the sand content of the slag soil is high, and the slag soil can be used as a grouting material after treatment; when various highly weathered clay rocks or soil layers are tunneled, the content of the generated muck is high, and the resource utilization difficulty is high due to the large viscosity of the mud blocks. Enterprises try to fire standard bricks by using the shield muck with the high mud content, on one hand, the sintering method has high energy consumption and pollutes the environment, on the other hand, brick firing plants are generally in suburbs, large excavation projects are in urban areas, and the muck transportation cost is high. Therefore, the resource utilization of the shield muck with high mud content is developed, and the method has important economic and environmental benefits.

Disclosure of Invention

The invention provides a geopolymer and a preparation method and application thereof, and aims to solve the technical problem that shield muck with high mud content is difficult to recycle.

The technical scheme adopted by the invention is as follows:

the geopolymer is prepared from at least fly ash, shield muck and an alkaline activator as raw materials, wherein the main component of the shield muck is clay, and the mass ratio of the fly ash to the dried shield muck is 1-2: 3; the mass ratio of the mixture of the fly ash and the dried shield muck to the alkaline activator is 1: 0.14-0.18.

Further, the shield muck needs to be dried and crushed before use.

Further, the shield residual soil is crushed and then screened, so that the particle size of the shield residual soil is smaller than 2 mm.

Furthermore, the water content of the fly ash and the water content of the dried shield muck are both less than 3%.

Further, the alkali activator is a mixed solution of water glass and a NaOH solution.

According to another aspect of the present invention, there is also provided a method of preparing the geopolymer described above, comprising the steps of:

(1) drying and crushing the shield muck to obtain treated shield muck; mixing the treated shield muck and fly ash in proportion to obtain a mixture;

(2) adding an alkaline activator into the mixture obtained in the step (1) in a spraying manner, and stirring to obtain a mixed wet material;

(3) and (3) putting the mixed wet material obtained in the step (2) into a mould, compacting, standing and demoulding to obtain the geopolymer.

Further, in the step (1), the shield muck is crushed and then screened, and the shield muck with the particle size of less than 2mm is mixed with the fly ash.

Further, the particle size of the fly ash is less than 2 mm.

Further, in the step (2), a closed spray stirring device is adopted to add the alkaline activator into the mixture.

Further, the stirring time in the step (2) is 5-10 min.

Further, the step (3) is specifically: filling the mixed wet material into a mold, and compacting while filling until the mold is filled; and then, compacting the mixed wet material on a hydraulic testing machine, gradually increasing the pressure of the hydraulic testing machine to 10-12 MPa, unloading, standing and demolding.

Further, the standing time in the step (3) is 20-28 h.

And (3) further, demolding and curing for 30-40 days.

Further, in the step (2), the alkali activator is a mixed solution of water glass and a NaOH solution, the concentration of the NaOH solution is 8-12 mol/L, and the modulus of the water glass is 2.4-3.2.

Further, before the mixed wet material in the step (3) is filled into a mould, the inner wall of the mould is coated with mineral oil.

Further, the demoulding mode in the step (3) is to use a soft hammer to hammer or carry out static pressure to push out the formed mixed wet material.

According to another aspect of the invention, the application of the geopolymer or the geopolymer prepared by the preparation method in building material products is further provided.

Furthermore, the building material product is one or more of standard bricks, pavement bricks, landscape retaining stones, kerbs, grass planting bricks, slope protection bricks, prefabricated drainage ditches and retaining wall building blocks.

The invention has the following beneficial effects:

1. the geopolymer is prepared by adopting the fly ash, the shield muck with high mud content and the alkaline activator as raw materials, wherein the main component of the shield muck with high mud content is clay which is dried to be used as fine aggregate, the fly ash is a volcanic ash material, the preparation raw materials do not comprise any type of traditional cementing materials such as cement, lime and the like, the large carbon emission is avoided, the cost is low, and the shield muck with high mud content is recycled; the geopolymer has extremely low porosity and extremely low permeability coefficient, high strength and good water resistance; the geopolymer is an oxide network structure system, cannot be oxidized and decomposed, has good durability, and can be used for building material products, underwater buildings, acid-resistant, alkali-resistant and high-temperature-resistant buildings and the like.

2. The preparation method of the geopolymer provided by the invention realizes resource utilization of the shield muck with high mud content, digests the shield muck, reduces the discharge of solid wastes, and generates economic benefits. Adding an alkaline activator into a mixture of the fly ash and the treated shield muck in a spraying manner, so that the particles of the mixture are uniformly wetted, and larger aggregates are avoided; and the mixed wet material is compressed in the die, so that the porosity of the mixed wet material is reduced, and the compactness of the mixed wet material is improved, so that the obtained geopolymer test piece has high strength and good water resistance.

3. The preparation method of the geopolymer has the advantages of simple process, mild reaction conditions and good repeatability, and is suitable for large-scale production.

4. The application of the geopolymer in building material products can digest the shield muck with high mud content, reduce the discharge of solid wastes, solve the problem of urban environment management and simultaneously generate long-term economic benefits.

In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic flow diagram of a process for the preparation of geopolymers according to the invention;

FIG. 2 is a schematic diagram of the uniaxial compressive stress-strain curve of a geopolymer of preferred embodiment 1 of the present invention;

FIG. 3 is a schematic representation of the failure mode of the geopolymer of the preferred embodiment 1 of the present invention.

FIG. 4 is a schematic representation of the uniaxial compressive stress-strain curve of a geopolymer of preferred embodiment 2 of the present invention;

FIG. 5 is a schematic representation of the failure mode of the geopolymer of the preferred embodiment 2 of the present invention.

FIG. 6 is a schematic representation of the uniaxial compressive stress-strain curve of a geopolymer of preferred embodiment 3 of the present invention;

FIG. 7 is a schematic representation of the failure mode of the geopolymer of the preferred embodiment 3 of the present invention.

FIG. 8 is a schematic representation of the uniaxial compressive stress-strain curve of a geopolymer of preferred embodiment 4 of the present invention;

FIG. 9 is a schematic representation of the failure mode of the geopolymer of the preferred embodiment 4 of the present invention.

FIG. 10 is a schematic representation of the uniaxial compressive stress-strain curve of a geopolymer of preferred embodiment 5 of the present invention;

FIG. 11 is a schematic representation of the failure mode of the geopolymer of the preferred embodiment 5 of the present invention.

FIG. 12 is a schematic representation of the uniaxial compressive stress-strain curve of a geopolymer of preferred embodiment 6 of the present invention;

FIG. 13 is a schematic representation of the failure mode of the geopolymer of the preferred embodiment 6 of the present invention.

FIG. 14 is a schematic representation of the uniaxial compressive stress strain curve of the geopolymer of preferred embodiment 7 of the present invention;

FIG. 15 is a schematic representation of the failure mode of the geopolymer of the preferred embodiment 7 of the present invention.

FIG. 16 is a schematic representation of the uniaxial compressive stress strain curve of a geopolymer of the preferred embodiment 8 of the present invention;

FIG. 17 is a schematic representation of the failure mode of the geopolymer of the preferred embodiment 8 of the present invention.

FIG. 18 is a schematic representation of the uniaxial compressive stress strain curve of a geopolymer of preferred embodiment 9 of the present invention;

FIG. 19 is a schematic representation of the failure mode of the geopolymer of the preferred embodiment 9 of the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

The invention provides a geopolymer which is prepared by taking fly ash, shield muck and an alkaline activator as raw materials, wherein the main component of the shield muck is clay, and the mass ratio of the fly ash to the dried shield muck is 1-2: 3; the mass ratio of the mixture of the fly ash and the dried shield residue soil to the alkaline activator is 1: 0.14-0.18.

The shield muck is muck with high mud content generated by the shield tunneling machine during tunneling of various highly weathered clay rocks or soil layers, and the mud blocks have high viscosity and high resource utilization difficulty. The shield muck is applied to the preparation of the geopolymer, so that the shield muck is digested, the discharge of solid wastes is reduced, and economic benefits are generated.

The geopolymer is prepared by adopting the fly ash, the shield muck with high mud content and the alkaline activator as raw materials, wherein the main component of the shield muck with high mud content is clay which is dried and then used as fine aggregate, the fly ash is a volcanic ash material, the prepared raw materials do not comprise any type of traditional cementing materials such as cement, lime and the like, the large carbon emission is avoided, the cost is low, and the resource utilization of the shield muck with high mud content is realized; the geopolymer has extremely low porosity and extremely low permeability coefficient, high strength and good water resistance; the geopolymer is an oxide network structure system, can not be oxidized and decomposed, has good durability, can be used for building material products, and the building material products comprise one or more of standard bricks, pavement bricks, landscape retaining stones, kerbs, grass planting bricks, slope protection bricks, prefabricated drainage ditches and retaining wall building blocks, and can also be used for underwater buildings, acid-resistant, alkali-resistant and high-temperature-resistant buildings and the like.

Preferably, the shield muck needs to be dried and crushed before use. The shield muck is high in mud content and high in water content, and needs to be dried before being used for preparing the geopolymer; when the water content of the used shield muck is more than 40%, dehydration is needed before drying. The crushing is beneficial to the full mixing of the shield muck and the fly ash, and the strength of the obtained geopolymer can be improved.

Preferably, the shield residual soil is crushed and then screened to ensure that the particle size is less than 2 mm. The particle size of the shield muck adopted is smaller than 2mm, so that on one hand, the shield muck is favorably and fully mixed with the fly ash, the uniform characteristic of a mixture is ensured, and the strength of the prepared test block is improved; on the other hand, local strength reduction caused by large mud masses is avoided.

Preferably, the water content of the fly ash and the water content of the dried shield muck are both less than 3%. The fly ash and the shield muck with the water content of less than 3 percent are adopted, so that the raw materials are conveniently ground into fine powder, and the powder with the particle size of less than 2mm is selected; on the other hand, the lower water content enables the fly ash and the shield muck to be fully and uniformly mixed, the compactness is higher after the alkali activator is added for mixing and compacting, and the strength of the obtained geopolymer is further improved.

Preferably, the alkali activator is a mixed solution of water glass and a NaOH solution. Wherein the concentration of the NaOH solution is 8-12 mol/L, and the modulus of the water glass is 2.4-3.2.

As a general inventive concept, the present invention also provides a method for preparing the geopolymer, comprising the steps of:

And (2) after the shield residual soil obtained by drying and crushing is mixed with the fly ash in proportion in the step (1), the mixture is dry-mixed for 5 minutes and uniformly mixed to obtain a mixture.

The preparation method of the geopolymer carries out resource utilization on the shield muck with high mud content, digests the shield muck, reduces the discharge of solid wastes and generates economic benefits. Adding an alkaline activator into a mixture of the fly ash and the treated shield muck in a spraying manner, so that the particles of the mixture are uniformly wetted, and larger aggregates are avoided; and the mixed wet material is compressed in the die, so that the porosity of the mixed wet material is reduced, and the compactness of the mixed wet material is improved, so that the prepared geopolymer test piece has higher strength and good water resistance. The preparation method of the geopolymer has the advantages of simple process, mild reaction conditions and good repeatability, and is suitable for large-scale production.

Preferably, in the step (1), the shield muck is crushed and then screened, and the shield muck with the particle size of less than 2mm is mixed with the fly ash. Preferably, the fly ash has a particle size of less than 2 mm. And (2) drying and crushing the shield muck in the step (1) to obtain fine particles, and sieving the fine particles with a sieve of 2mm to obtain the shield muck with the particle size of less than 2 mm. And grinding the fly ash sample into fine powder and sieving the fine powder by a 2mm sieve to obtain the fly ash with the particle size of less than 2 mm. The particle sizes of the shield muck and the fly ash are smaller than 2mm, so that on one hand, the shield muck and the fly ash are fully mixed, the uniform characteristic of a mixture is ensured, and the strength of the prepared geopolymer test block is improved; on the other hand, local strength reduction caused by large mud masses is avoided.

Preferably, the alkaline activator is added to the mixture in step (2) by using a closed spray stirring device. And (3) adopting a closed spraying and stirring device, stirring the fly ash and the treated dry materials of the shield residual soil, and spraying the excitant in a mist form, so as to avoid the agglomeration caused by uneven wetting.

Preferably, the stirring time in the step (2) is 5-10 min. After the alkaline activator is added in the step (2), the stirring time cannot be too short or too long, and the fly ash, the treated shield muck and the alkaline activator cannot be fully contacted, so that the wetting degree is uneven; the stirring time is too long and the above-mentioned substances have already reacted, at which point further stirring destroys the geopolymer produced.

Preferably, the step (3) is specifically: filling the mixed wet material into a mold, and compacting while filling until the mold is filled; and then, compacting the mixed wet material on a hydraulic testing machine, gradually increasing the pressure of the hydraulic testing machine to 10-12 MPa, unloading, standing and demolding. When the mixed wet material is compacted while being loaded and formed on a hydraulic control press, slow loading is adopted, the pressure is gradually increased to 10-12 MPa, the pressure lasts for 5s after the maximum pressure is reached, and then the pressure is unloaded. The compactness of the mixed wet material is improved through static pressure, so that the strength of the geopolymer is improved. In the operation process, the applied pressure is too small, so that the compactness of the mixed wet material is insufficient, and the strength is low; when the applied pressure is too large, the mixed wet material is extruded out from the gap between the pressure head and the die. The mixed wet material is kept stand before demoulding, so that the mixed wet material in the mould can fully react at normal temperature, and the strength of the geopolymer is obviously improved.

Preferably, the standing time in the step (3) is 20-28 hours. Preferably, in the step (3), the mold is demolded and then cured for 30 to 40 days. By adopting the standing and maintaining time, the mixed wet material can completely react at normal temperature, so that the geopolymer has better forming effect and higher strength.

Preferably, in the step (2), the alkali activator is a mixed solution of water glass and a NaOH solution, the concentration of the NaOH solution is 8-12 mol/L, and the modulus of the water glass is 2.4-3.2. The mixed solution of water glass and NaOH solution is used as an alkaline activator, so that the alkali activator reacts with the fly ash more completely, and the obtained geopolymer has higher strength.

Preferably, before the mixed wet material in the step (3) is filled into the mould, the inner wall of the mould is coated with mineral oil. The above operation is favorable for demoulding the mixed wet material after forming.

Preferably, the step (3) of removing the mold is performed by hammering the molded wet mixture with a soft hammer or by static pressure. The clearance between the mixed wet material and the die is full in the forming process of the mixed wet material, and the friction force is large, so that the demoulding is difficult; in addition, the strength of the geopolymer in the early stage is not high, the geopolymer cannot bear large load, and the mixed wet material is pushed out in a soft hammer hammering or static pressure mode, so that initial damage generated in the geopolymer is avoided, and the final strength is lower.

As a general inventive concept, the application of the geopolymer or the geopolymer prepared by the preparation method in building material products is also provided. The new building material product manufactured by the geopolymer not only digests the residue soil, reduces the discharge of solid waste, solves the problem of urban environmental management, but also generates long-term economic benefit.

Preferably, the building material product is one or more of standard bricks, pavement bricks, landscape retaining stones, kerbs, grass planting bricks, slope protection bricks, prefabricated drainage ditches and retaining wall building blocks. The geopolymer or the geopolymer prepared by the preparation method is mainly applied to one or more building material products, not only consumes shield muck with high mud content and protects the environment, but also has obvious economic benefit.

In the following examples, various reagents are commercially available.

Example 1

The geopolymer is prepared from the following raw materials: the shield muck which is dried, crushed and screened and has the particle size of less than 2mm and the water content of less than 3 percent is mixed with the fly ash according to the mass ratio of 3: 1 to form a mixture, the mass ratio of an alkaline activator to the mixture is 0.14: 1, wherein the alkaline activator is a mixed solution of water glass and a NaOH solution, the mass ratio of the water glass solution to the NaOH solution is 1.8: 1, the NaOH concentration is 8mol/L, and the water glass modulus is 3.0. The shield muck is high in mud content and mainly comprises clay.

The preparation method of the geopolymer comprises the following steps:

(1) drying the shield muck with high mud content, crushing, and sieving by a 2mm sieve to obtain shield muck with the particle size of less than 2mm, namely fine grained soil; grinding the dried fly ash into fine powder, and sieving the fine powder by a sieve with the particle size of 2mm to obtain the fly ash with the particle size of less than 2mm, namely fine ash; and mixing the fine soil and fine ash, and dry-stirring for 5min until uniform to obtain a mixture. (2) Adding the alkaline activator into the mixture in a closed spraying and stirring device in a spraying manner, and stirring for 10 minutes until the wetting degree of all materials is close to obtain a mixed wet material. (3) And (3) putting the mixed wet material into an iron mould with the diameter of 50mm and the height of 100mm, manually compacting while filling, compacting the material by using a load of 10MPa, standing for 24 hours, demoulding to obtain the geopolymer, and then curing for 35 days under the normal temperature and humidity condition. Referring to fig. 1, a flow diagram for preparing a geopolymer is shown.

The end faces of the test pieces of the geopolymer are polished to be flat and smooth, an Instron rigidity testing machine is adopted to carry out a uniaxial compression experiment, the stress-strain full curve is measured, and referring to FIG. 2, the peak compressive strengths of the three test pieces manufactured according to the proportion are respectively 13.05MPa, 11.785MPa and 13.001 MPa. Referring to fig. 3, the broken fragments of the geopolymer test piece are short, the penetration is not strong, and the broken cone formed at the top is obvious.

Example 2

The geopolymer is prepared from the following raw materials: the shield muck which is dried, crushed and screened and has the particle size of less than 2mm and the water content of less than 3 percent is mixed with the fly ash according to the mass ratio of 3: 1 to form a mixture, the mass ratio of an alkaline activator to the mixture is 0.16: 1, wherein the alkaline activator is a mixed solution of water glass and a NaOH solution, the mass ratio of the water glass solution to the NaOH solution is 2: 1, the concentration of NaOH is 10mol/L, and the modulus of the water glass is 3.0. The shield muck is high in mud content and mainly comprises clay.

This example prepared geopolymers in the same manner as example 1.

The end faces of the test pieces of the geopolymer are polished to be flat and smooth, an Instron rigidity testing machine is adopted to carry out a uniaxial compression experiment, the stress-strain full curve is measured, and referring to FIG. 4, the peak compressive strengths of the three test pieces manufactured according to the proportion are 18.463MPa, 22.235MPa and 20.098MPa respectively. Referring to fig. 5, after the specimen of geopolymer breaks down, the bottom forms a distinct cone.

Example 3

The geopolymer is prepared from the following raw materials: the shield muck which is dried, crushed and screened and has the particle size of less than 2mm and the water content of less than 3 percent is mixed with the fly ash according to the mass ratio of 3: 1 to form a mixture, the mass ratio of an alkaline activator to the mixture is 0.18: 1, wherein the alkaline activator is a mixed solution of water glass and a NaOH solution, the mass ratio of the water glass solution to the NaOH solution is 2.2: 1, the NaOH concentration is 12mol/L, and the water glass modulus is 3.0. The shield muck is high in mud content and mainly comprises clay.

This example prepared geopolymers in the same manner as example 1.

The end faces of the test pieces of the geopolymer are polished to be flat and smooth, an Instron rigidity testing machine is adopted to carry out a uniaxial compression experiment, the stress-strain full curve is measured, and referring to FIG. 6, the peak compressive strengths of the three test pieces manufactured according to the proportion are 18.321MPa, 18.192MPa and 16.1MPa respectively. Referring to fig. 7, after the specimen of geopolymer is broken, a significant cone is formed at the top.

Example 4

The geopolymer is prepared from the following raw materials: the shield muck which is dried, crushed and screened and has the particle size of less than 2mm and the water content of less than 3 percent is mixed with the fly ash according to the mass ratio of 2: 1 to form a mixture, the mass ratio of an alkaline activator to the mixture is 0.16: 1, wherein the alkaline activator is a mixed solution of water glass and a NaOH solution, the mass ratio of the water glass solution to the NaOH solution is 1.8: 1, the NaOH concentration is 12mol/L, and the water glass modulus is 3.0. The shield muck is high in mud content and mainly comprises clay.

This example prepared geopolymers in the same manner as example 1.

The end faces of the test pieces of the geopolymer are polished to be flat and smooth, an Instron rigidity testing machine is adopted to carry out a uniaxial compression experiment, the stress-strain full curve is measured, and referring to FIG. 8, the peak compressive strengths of the three test pieces manufactured according to the proportion are 24.991MPa, 26.922MPa and 26.624MPa respectively. Referring to fig. 9, after the sample of geopolymer is broken, the fragment penetration is good, and the bottom forms an obvious cone, indicating that the strength is fully exerted.

Example 5

The geopolymer is prepared from the following raw materials: the shield muck which is dried, crushed and screened and has the particle size of less than 2mm and the water content of less than 3 percent is mixed with the fly ash according to the mass ratio of 2: 1 to form a mixture, the mass ratio of the alkaline activator to the mixture is 0.18: 1, wherein the alkaline activator is a mixed solution of water glass and NaOH solution, the mass ratio of the water glass solution to the NaOH solution is 2: 1, the concentration of NaOH is 8mol/L, and the modulus of the water glass is 3.0. The shield muck is high in mud content and mainly comprises clay.

This example prepared geopolymers in the same manner as example 1.

The end faces of the test pieces of the geopolymer are polished to be flat and smooth, an Instron rigidity testing machine is adopted to carry out a uniaxial compression experiment, the stress-strain full curve is measured, and referring to FIG. 10, the peak compressive strengths of the three test pieces manufactured according to the proportion are 21.563MPa, 21.168MPa and 21.129MPa respectively. Referring to fig. 11, after the specimen of geopolymer breaks, near conical breaking, the outer fragment penetration is better.

Example 6

The geopolymer is prepared from the following raw materials: the shield muck which is dried, crushed and screened and has the particle size of less than 2mm and the water content of less than 3 percent is mixed with the fly ash according to the mass ratio of 2: 1 to form a mixture, the mass ratio of an alkaline activator to the mixture is 0.14: 1, wherein the alkaline activator is a mixed solution of water glass and a NaOH solution, the mass ratio of the water glass solution to the NaOH solution is 2.2: 1, the NaOH concentration is 10mol/L, and the water glass modulus is 3.0. The shield muck is high in mud content and mainly comprises clay.

This example prepared geopolymers in the same manner as example 1.

The end faces of the test pieces of the geopolymer are polished to be flat and smooth, an Instron rigidity testing machine is adopted to carry out a uniaxial compression experiment, the stress-strain full curve is measured, and referring to FIG. 12, the peak compressive strengths of the three test pieces manufactured according to the proportion are 14.510MPa, 13.591MPa and 13.501MPa respectively. Referring to fig. 13, after the sample of geopolymer is destroyed, the size of the fragments is greatly different and the thickness is not uniform, which is close to the overall shear destruction.

Example 7

The geopolymer is prepared from the following raw materials: the shield muck which is dried, crushed and screened and has the particle size of less than 2mm and the water content of less than 3 percent is mixed with the fly ash according to the mass ratio of 3: 2 to form a mixture, the mass ratio of an alkaline activator to the mixture is 0.18: 1, wherein the alkaline activator is a mixed solution of water glass and a NaOH solution, the mass ratio of the water glass solution to the NaOH solution is 1.8: 1, the NaOH concentration is 10mol/L, and the water glass modulus is 3.0. The shield muck is high in mud content and mainly comprises clay.

This example prepared geopolymers in the same manner as example 1.

The end faces of the test pieces of the geopolymer are polished to be flat and smooth, an Instron rigidity testing machine is adopted to carry out a uniaxial compression experiment, the stress-strain full curve is measured, and referring to FIG. 14, the peak compressive strengths of the three test pieces manufactured according to the proportion are 25.988MPa, 25.785MPa and 27.455MPa respectively. Referring to fig. 15, after the geopolymer test piece is damaged, the periphery of the test piece is stripped in an integral strip shape, and the fragment penetration is good.

Example 8

The geopolymer is prepared from the following raw materials: the shield muck which is dried, crushed and screened and has the particle size of less than 2mm and the water content of less than 3 percent is mixed with the fly ash according to the mass ratio of 3: 2 to form a mixture, the mass ratio of an alkaline activator to the mixture is 0.14: 1, wherein the alkaline activator is a mixed solution of water glass and a NaOH solution, the mass ratio of the water glass solution to the NaOH solution is 2: 1, the concentration of NaOH is 12mol/L, and the modulus of the water glass is 3.0. The shield muck is high in mud content and mainly comprises clay.

This example prepared geopolymers in the same manner as example 1.

The end faces of the test pieces of the geopolymer are polished to be flat and smooth, an Instron rigidity testing machine is adopted to carry out a uniaxial compression experiment, the stress-strain full curve is measured, and referring to fig. 16, the peak compressive strengths of the three test pieces manufactured according to the proportion are 15.848MPa, 18.067MPa and 16.86MPa respectively. Referring to fig. 17, after the specimen of geopolymer is broken, the specimen approaches the shear failure shape and the fragments are not uniform in size.

Example 9

The geopolymer is prepared from the following raw materials: the shield muck which is dried, crushed and screened and has the particle size of less than 2mm and the water content of less than 3 percent is mixed with the fly ash according to the mass ratio of 3: 2 to form a mixture, the mass ratio of an alkaline activator to the mixture is 0.16: 1, wherein the alkaline activator is a mixed solution of water glass and a NaOH solution, the mass ratio of the water glass solution to the NaOH solution is 2.2: 1, the NaOH concentration is 8mol/L, and the water glass modulus is 3.0. The shield muck is high in mud content and mainly comprises clay.

This example prepared geopolymers in the same manner as example 1.

The end faces of the test pieces of the geopolymer are polished to be flat and smooth, an Instron rigidity testing machine is adopted to carry out a uniaxial compression experiment, the stress-strain full curve is measured, and referring to fig. 18, the peak compressive strengths of the three test pieces manufactured according to the proportion are 15.216MPa, 17.068MPa and 15.641MPa respectively. Referring to fig. 19, after the specimen of geopolymer is broken, the shape of the broken specimen is close to the shear failure shape, and the fragments are not uniform in size.

The parameters in the preparation methods of the geopolymers of examples 1-9 are obtained by designing orthogonal test schemes, and the results of the orthogonal tests are analyzed to obtain table 1. From the results in table 1, it can be seen that various factors affect the geopolymer strength: the mass ratio of the mixture of the alkaline activator, the fly ash and the dried shield muck is greater than the mass ratio of the water glass to the NaOH solution is greater than the mass ratio of the fly ash to the dried shield muck, the mass ratio of the alkaline activator to the mixture is 0.18, the mass ratio of the water glass to the NaOH solution is 1.8, the mass ratio of the NaOH solution is 12mol/L, the mass ratio of the fly ash to the dried shield muck is 1/2, and the influence is small when the molar concentration of the NaOH solution is greater than 10 mol/L.

TABLE 1 orthogonal experimental design and results

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A geopolymer characterized in that,

the geopolymer is prepared from at least fly ash, shield muck and an alkaline activator as raw materials, wherein the main component of the shield muck is clay, and the mass ratio of the fly ash to the dried shield muck is 1-2: 3; the mass ratio of the mixture of the fly ash and the dried shield muck to the alkaline activator is 1: 0.14-0.18;

the alkaline excitant is a mixed solution of water glass and NaOH solution.

2. The geopolymer of claim 1, wherein,

the shield muck needs to be dried and crushed before use.

3. The geopolymer of claim 2, wherein,

and crushing and screening the shield muck to ensure that the particle size of the shield muck is less than 2 mm.

4. The geopolymer of claim 1, wherein,

the water content of the fly ash and the water content of the dried shield muck are both less than 3%.

5. A method of preparing a geopolymer according to any one of claims 1 to 4, characterised in that it comprises the following steps:

(1) drying and crushing the shield muck to obtain the treated shield muck; mixing the treated shield muck with the fly ash according to a proportion to obtain a mixture;

6. The method of producing a geopolymer according to claim 5,

in the step (1), the shield muck is crushed and then screened, and the shield muck with the particle size of less than 2mm is mixed with the fly ash; and/or

The particle size of the fly ash is less than 2 mm.

7. The method of producing a geopolymer according to claim 5,

adding the alkaline activator into the mixture by adopting a closed spraying and stirring device in the step (2); and/or

And (3) stirring time in the step (2) is 5-10 min.

8. The method of producing a geopolymer according to claim 5,

the step (3) is specifically as follows: filling the mixed wet material into a mold, and compacting while filling until the mold is filled; and then, compacting the mixed wet material on a hydraulic testing machine, gradually increasing the pressure of the hydraulic testing machine to 10-12 MPa, unloading, standing and demolding.

9. The method of producing a geopolymer according to claim 5,

the standing time in the step (3) is 20-28 h; and/or

And (4) curing for 30-40 days after demolding in the step (3).

10. The method of producing a geopolymer according to claim 5,

in the step (2), the alkali activator is a mixed solution of water glass and a NaOH solution, the concentration of the NaOH solution is 8-12 mol/L, and the modulus of the water glass is 2.4-3.2.

11. The method of producing a geopolymer according to claim 5,

before the mixed wet material in the step (3) is loaded into a mould, coating mineral oil on the inner wall of the mould; and/or

And (4) in the step (3), the demoulding mode is to push out the formed mixed wet material by adopting a soft hammer to hammer or static pressure.

12. Use of a geopolymer according to any one of claims 1 to 4 or produced by the method of any one of claims 5 to 9 in a building material product.

13. The method of producing a geopolymer according to claim 12,

the building material product is one or more of standard brick, pavior brick, landscape soil retaining stone, curb stone, grass planting brick, slope protection brick, prefabricated escape canal, barricade building block.