CN108218274A - Improve inorganic dispersant of geo-polymer slurry rheology energy and its preparation method and application - Google Patents

Abstract

The present invention provides a kind of inorganic dispersants for improving geo-polymer slurry rheology energy and its preparation method and application, are related to the production preparation field of construction material.The preparation method of the inorganic dispersant includes：Fly ash grain and lye are mixed and are incorporated at 50~80 DEG C after 1~6h of stirring, then fly ash grain with the solution containing low-surface energy substance is mixed and 0.5~1.5h is impregnated at 55~65 DEG C.The inorganic dispersant prepared by this method has hydrophobic surface, and ' ball ' effect can be played in high alkalinity and highly viscous geo-polymer slurry, reduces plastic viscosity, improves the rheological property of geo-polymer slurry.

Description

Inorganic dispersant for improving rheological properties of geopolymer slurry and its preparation method and use

technical field

The invention relates to the field of production and preparation of building materials, in particular to an inorganic dispersant for improving the rheological properties of geopolymer slurry, its preparation method and application.

Background technique

Geopolymer is a kind of green inorganic gelling material prepared by reacting active aluminum-siliceous raw materials (metakaolin, fly ash and slag, etc.) with alkaline activators. Geopolymers have excellent properties such as early strength, compactness and corrosion resistance, and can make high-value use of industrial waste, so they have broad application prospects in special engineering fields such as rapid repair and solid waste treatment.

However, since the preparation process of the geopolymer requires the use of a strongly alkaline and high-viscosity solution made of sodium hydroxide and water glass as the activator, this leads to poor rheological properties of the geopolymer slurry and difficult workability. control. Polymer dispersants such as naphthalene, lignosulfonate, and polycarboxylic acid, which are conventionally used in Portland cement-based materials, have little effect in geopolymer slurry, and there is no preparation at home and abroad that can effectively improve the quality of geopolymers. Matching admixture for slurry rheological properties. This brings great difficulties to the molding and pumping operations of the slurry, which seriously affects the application and popularization of geopolymer materials.

Contents of the invention

The object of the present invention is to provide an inorganic dispersant for improving the rheological properties of geopolymer slurry and its preparation method and application. The "ball" effect is exerted in the slurry, the plastic viscosity is reduced, and the rheological properties of the geopolymer slurry are improved.

In order to realize the above-mentioned purpose of the present invention, special adopt following technical scheme:

A preparation method of an inorganic dispersant for improving the rheological properties of geopolymer slurry, comprising:

Mix fly ash particles with lye and stir at 50-80°C for 1-6 hours, then mix fly ash particles with a solution containing low surface energy substances and impregnate at 55-65°C for 0.5-1.5 hours .

An inorganic dispersant prepared by the above preparation method.

An application of the above-mentioned inorganic dispersant in improving the rheological properties of geopolymer slurry.

Compared with the prior art, the beneficial effects of the present invention include, for example:

1. Existing polymer dispersants have little effect in highly alkaline and high-viscosity geopolymer slurries, but the present invention discloses an inorganic dispersant that can improve the rheological properties of geopolymer slurries for the first time, The inorganic dispersant treated with superhydrophobic surface can significantly improve the rheological properties of geopolymer slurry, which is helpful for the popularization and application of geopolymer materials.

2. This inorganic dispersant can take advantage of the non-wetting properties of the super-hydrophobic surface of fly ash particles, give full play to the "ball" effect and steric hindrance effect of fly ash particles, and reduce the impact on high-alkaline and high-viscosity geological conditions. The surface viscosity between particles in the polymer slurry environment can avoid particle agglomeration, reduce the plastic viscosity of the slurry, and then play the role of water reduction and dispersion, and improve the rheological properties of the geopolymer slurry.

3. The fly ash used in the present invention is a common building material with low price. A series of methods such as chemical etching and surface low-energy modification for preparing inorganic dispersants are easy to operate, and the preparation process is easy to popularize.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art.

Fig. 1 is the fly ash particle after surface roughening treatment;

Figure 2 shows the fly ash particles after sieving and ultrasonic cleaning.

Detailed ways

Embodiments of the present invention will be described in detail below in conjunction with examples, but those skilled in the art will understand that the following examples are only for illustrating the present invention, and should not be considered as limiting the scope of the present invention. Those who do not indicate the specific conditions in the examples are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used were not indicated by the manufacturer, and they were all conventional products that could be purchased from the market.

The applicant's research found that mixing fly ash particles with a spherical shape into cement-based materials can exert a "rolling ball" effect, reduce the friction loss between cement particles, and improve the rheological properties of the slurry. However, the incorporation of fly ash particles into geopolymer slurries has no significant dispersion effect. After careful analysis and unremitting exploration, the applicant found that this is because after the fly ash particles contacted with the high-viscosity alkali activator, the frictional resistance of mutual movement between the particles was too high, resulting in the inability to exert the "ball" effect.

Therefore, in order to exert the "ball" effect of fly ash particles in the geopolymer slurry, this embodiment provides an inorganic dispersant, which uses fly ash particles as raw materials, through chemical etching and surface hydrophobic The treatment makes the fly ash particles have a hydrophobic surface, thereby reducing the plastic viscosity of the geopolymer slurry and improving the rheological properties of the geopolymer slurry.

The present embodiment also provides the preparation method of the inorganic dispersant for improving the rheological properties of the geopolymer slurry, which includes:

Step S1. Chemical etching: the fly ash particles are mixed with lye and stirred at 50-80° C. for 1-6 hours.

Mix fly ash particles with lye, and carry out chemical etching under constant stirring at 50-80°C (or 60-70°C; or 63-68°C) to construct rough particle surfaces. The etched fly ash microspheres are shown in Figure 1. Nanoscale particles and pit structures have formed on the surface of the microspheres, which can reduce the wettability of the fly ash microspheres in the liquid phase.

Further, the alkali solution has a concentration of 5-10 mol/L, or 6-9 mol/L, or 7-8 mol/L. The solid-to-liquid ratio of the fly ash particles to the lye is 1:25-35, or 1:26-34; or 1:28-32; or 1:29-31. Preferably, the lye is NaOH solution or KOH solution.

Further, the particle size of the fly ash particles is less than 80 μm, more preferably, the particle size is 60-80 μm, or 65-75 μm. Fly ash particles of this particle size are obtained by passing the primary fly ash through a square hole sieve of about 180 mesh. Class I fly ash is a common building material with low price. Fly ash particles within the particle size range of 70-90 μm can better exert the "ball" effect and steric hindrance effect, and help to further improve the rheological properties of the geopolymer slurry.

Further, before the fly ash particles are mixed with the lye, a step of washing with an alcohol solution is also included. More preferably, a method of ultrasonically cleaning the fly ash particles is mixed with an ethanol solution. The cleaned and dried fly ash microspheres are shown in Figure 2. Ultrasonic treatment can clean the attachments on the surface of the microspheres, improve the surface smoothness, and facilitate the hydrophobic modification on the surface of the fly ash particles.

Step S2. Surface hydrophobic treatment: the fly ash particles are mixed with a solution containing low surface energy substances, and soaked at 55-65° C. for 0.5-1.5 hours.

Mix the roughened fly ash microspheres with the prepared solution containing low surface energy substances, and immerse them at 55-65°C for 0.5-1.5 hours (or at 57-63°C for 0.8-1.2h), and perform low-energy Surface modification makes the fly ash microspheres with rough surface have a hydrophobic surface, thus possessing super-hydrophobic properties.

Further, low surface energy substances include heptadecafluorodecyltrimethoxysilane, heptadecafluorodecyltriethoxysilane, tridecafluorooctyltriethoxysilane and 1H,1H,2H,2H-perfluoro One or more of octyltrichlorosilane.

Further, the concentration of the low surface energy substance in the solution containing the low surface energy substance is 0.7-1.3 wt%, or 0.8-1.2 wt%, or 0.9-1.1 wt%.

Further, the solvent in the solution containing the low surface energy substance is at least one of ethanol, methanol and propanol, more preferably, ethanol is used as the solvent.

Further, it also includes drying the impregnated fly ash particles in an oxygen-free environment at 100-110° C. for 1.5-2.5 hours. Wherein, the oxygen-free environment is an environment protected by nitrogen or an inert gas. More preferably, the drying step is: drying the impregnated fly ash particles in a nitrogen environment at 103-107° C. for 1.8-2.2 hours.

This embodiment also provides an application of an inorganic dispersant in improving the rheological properties of a geopolymer slurry, which includes: mixing the above-mentioned inorganic dispersant with the geopolymer slurry at a doping amount of 2 to 8 wt%. .

Further, the geopolymer slurry is mixed and stirred for 80-120s by mixing the powder raw material with pozzolanic activity and the liquid activator (a mixture of NaOH and water glass, with a modulus of 1.5-1.7) according to the mass ratio of 1:0.8-1.2 be made of. Wherein, the powder raw material with pozzolanic activity is one or more of fly ash, granulated blast furnace slag and metakaolin.

Incorporating such inorganic dispersants can take advantage of the non-wetting properties of the super-hydrophobic surface of fly ash particles, give full play to the "balling" effect and steric hindrance effect of fly ash particles, and reduce the impact on high-viscosity geopolymer slurry. The surface viscosity between particles in the environment can avoid particle agglomeration, reduce the plastic viscosity of geopolymer slurry, and then play the role of water reduction and dispersion, and improve the rheological properties of the slurry.

Below in conjunction with embodiment, feature and performance of the present invention are described in further detail:

Example 1

This embodiment provides an inorganic dispersant for improving the rheological properties of geopolymer slurry, and its preparation method comprises:

Pass the primary fly ash through a 180-mesh square hole sieve, and take the sieved residue to obtain spherical fly ash particles with a particle size of less than 80 μm. Mix fly ash particles with ethanol solution for ultrasonic cleaning, after cleaning, mix with NaOH solution (8mol/L) at a solid-to-liquid ratio of 1:30, stir for 3 hours under hydrothermal conditions at 50°C for chemical etching, and rough particle surfaces .

Using ethanol as a solvent, heptadecafluorodecyltrimethoxysilane was added to prepare a 1 wt% heptadecafluorodecyltrimethoxysilane/ethanol solution. The roughened fly ash particles were mixed with the prepared solution, and immersed at 60°C for 1 hour to perform low-energy surface modification. The impregnated microspheres were dried for 2 h at 105 °C under _N2 environment to obtain an inorganic dispersant.

Fly ash and liquid activator (a mixture of NaOH and water glass, modulus 1.6) were mixed at a mass ratio of 1:1, and stirred for 100 s to prepare a fly ash-based geopolymer slurry. The prepared inorganic dispersant was mixed with the geopolymer slurry in an amount of 2%, and stirred for 60s to mix well. A rotary viscometer was used to compare and calculate the change of the plastic viscosity of the slurry before and after adding such a dispersant. The geopolymer slurry was formed into a test piece, and the standard curing was 28 days after demoulding, and the influence of the dispersant on the mechanical properties of the hardened body was analyzed.

Example 2

This embodiment provides an inorganic dispersant for improving the rheological properties of geopolymer slurry, and its preparation method comprises:

Pass the primary fly ash through a 180-mesh square hole sieve, and take the sieved residue to obtain spherical particles with a particle size of less than 80 μm. Mix fly ash particles with ethanol solution for ultrasonic cleaning, after cleaning, mix with prepared 10mol/L NaOH solution at a solid-to-liquid ratio of 1:30, stir for 2 hours under hydrothermal conditions at 70°C for chemical etching, the structure is rough particle surface.

Using ethanol as a solvent, add heptadecafluorodecyltriethoxysilane to configure a 1wt% heptadecafluorodecyltriethoxysilane/ethanol solution, and mix the roughened fly ash particles with the prepared solution , dipped at 60°C for 1h to perform low-energy surface modification. The impregnated fly ash particles were dried for 2 h at 105 °C under _N2 environment to obtain an inorganic dispersant.

Metakaolin and liquid activator (a mixture of NaOH and water glass, modulus 1.6) were mixed at a mass ratio of 1:1, and stirred for 100 s to prepare a metakaolin-based geopolymer slurry. The inorganic dispersant is mixed with the geopolymer slurry in an amount of 8%, and stirred for 60s to mix well. A rotary viscometer was used to compare and calculate the change of the plastic viscosity of the slurry before and after adding such a dispersant. The geopolymer slurry was formed into a test piece, and the standard curing was 28 days after demoulding, and the influence of the dispersant on the mechanical properties of the hardened body was analyzed.

Example 3

This embodiment provides an inorganic dispersant for improving the rheological properties of geopolymer slurry, and its preparation method comprises:

Pass the primary fly ash through a 180-mesh square hole sieve, and take the sieved residue to obtain spherical particles with a particle size of less than 80 μm. Mix fly ash particles with ethanol solution for ultrasonic cleaning, after cleaning, mix with prepared 5mol/L NaOH solution at a solid-to-liquid ratio of 1:30, stir for 6 hours under hydrothermal conditions at 60°C for chemical etching, and the structure is rough particle surface.

Using ethanol as a solvent, add tridecafluorooctyltriethoxysilane to configure a 1wt% tridecafluorooctyltriethoxysilane/ethanol solution, and mix the roughened fly ash particles with the prepared solution , dipped at 60°C for 1h to perform low-energy surface modification. The impregnated microspheres were dried for 2 h at 105 °C under _N2 environment to obtain an inorganic dispersant.

Granulated blast furnace slag was mixed with liquid activator (a mixture of NaOH and water glass, modulus 1.6) at a mass ratio of 1:1, and stirred for 100 s to obtain a slag-based geopolymer slurry. The inorganic dispersant is mixed with the geopolymer slurry in an amount of 8%, and stirred for 60s to mix well. A rotary viscometer was used to compare and calculate the change of the plastic viscosity of the slurry before and after adding such a dispersant. The geopolymer slurry was formed into a test piece, and the standard curing was 28 days after demoulding, and the influence of the dispersant on the mechanical properties of the hardened body was analyzed.

The rheological performance analysis of experimental example 1 geopolymer

At 20°C, a rotational viscometer (Chandler-Model 3530) was used to compare and calculate the change of plastic viscosity of geopolymer slurry before and after adding inorganic dispersant.

Read the shear stress of the slurry at the rotor speed of 3/6/10/20/30/60/100/200/300/600rpm, use the Bingham model (formula 1) to fit the data, and calculate the slurry The plastic viscosity of the body.

τ=τ ₀ +ηγ (1)

where τ is the shear stress, γ is the shear rate, _τ0 is the yield strength, and η is the plastic viscosity.

Table 1 shows the plastic viscosities of the geopolymer slurries provided in Examples 1-3, and the corresponding plastic viscosities of the comparative samples not mixed with inorganic dispersants.

Table 1 Comparative analysis of plastic viscosity of geopolymer slurry

The experimental results show that for the geopolymers of fly ash, metakaolin and slag, the plastic viscosity of the slurry is reduced by 73.5%, 70.7% and 73.3% respectively after adding powder inorganic dispersant. This shows that this type of dispersant has a good water-reducing dispersion effect in highly alkaline and high-viscosity geopolymer slurry, and effectively improves the rheological properties of the slurry.

Experimental Example 2 Compressive Strength Test of Geopolymer Hardened Body

The WHY-200 universal testing machine was used to compare and measure the change of compressive strength of geopolymer hardened body before and after adding inorganic dispersant.

The cube geopolymer specimens with dimensions of 30mm×30mm×30mm were tested for compressive strength after being aged for 28 days, and the loading rate was 0.5mm/min. Take the average value after testing 6 test blocks for each group of samples.

Table 2 shows the compressive strength of the geopolymer hardened body provided by Examples 1-3, and the corresponding compressive strength of the comparative sample not mixed with inorganic dispersant.

Table 2 Comparative analysis of compressive strength of geopolymer hardened body

The experimental results show that for geopolymers with three matrices such as fly ash, metakaolin and slag, the compressive strength of the hardened body does not decrease significantly after the inorganic dispersant is added. Strength development was not adversely affected.

While particular embodiments of the invention have been illustrated and described, it should be appreciated that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims (10)

1. a kind of preparation method for the inorganic dispersant for improving geo-polymer slurry rheology energy, which is characterized in that it includes：

Fly ash grain and lye are mixed and are incorporated at 50~80 DEG C after 1~6h of stirring, then by the fly ash grain with containing The solution mixing of low-surface energy substance simultaneously impregnates 0.5~1.5h at 55~65 DEG C.

2. the preparation method of the inorganic dispersant according to claim 1 for improving geo-polymer slurry rheology energy, It is characterized in that, the low-surface energy substance includes 17 fluorine decyl trimethoxy silanes, 17 fluorine decyl triethoxysilanes, ten Trifluoro octyltri-ethoxysilane and 1H, 1H, 2H are one or more in 2H-perfluoro capryl trichlorosilane.

3. the preparation method of the inorganic dispersant according to claim 1 for improving geo-polymer slurry rheology energy, Be characterized in that, low-surface energy substance described in the solution containing the low-surface energy substance a concentration of 0.7~ 1.3wt%.

4. the preparation method of the inorganic dispersant according to claim 1 for improving geo-polymer slurry rheology energy, It is characterized in that, the solvent in the solution containing the low-surface energy substance is at least one of ethyl alcohol, methanol and propyl alcohol.

5. the preparation method of the inorganic dispersant according to claim 1 for improving geo-polymer slurry rheology energy, It is characterized in that, the lye is a concentration of 5-10mol/L, and the solid-to-liquid ratio of the fly ash grain and the lye is 1：25~ 35。

6. the preparation method of the inorganic dispersant according to claim 1 for improving geo-polymer slurry rheology energy, It is characterized in that, the fly ash grain further includes the step of being cleaned with alcoholic solution before being mixed with the lye.

7. the preparation method of the inorganic dispersant according to claim 1 for improving geo-polymer slurry rheology energy, Be characterized in that, further include will dry 1.5 under oxygen-free environment of the fly ash grain at 100~110 DEG C after dipping~ 2.5h。

8. a kind of inorganic dispersant as made from claim 1~7 any one of them preparation method.

9. a kind of application of inorganic dispersant according to claim 8 in geo-polymer slurry rheology energy is improved.

10. application according to claim 9, which is characterized in that the inorganic dispersant by 2~8wt% the amount of mixing with The geo-polymer slurry mixing.