CN113929337A

CN113929337A - Ion absorption ceramsite and preparation method thereof

Info

Publication number: CN113929337A
Application number: CN202111259924.XA
Authority: CN
Inventors: 杨文�; 高育欣; 吴雄; 马建峰; 高达; 曾超; 徐晶晶
Original assignee: Building Materials Science Research Institute Co Ltd of China West Construction Group Co Ltd
Current assignee: Building Materials Science Research Institute Co Ltd of China West Construction Group Co Ltd
Priority date: 2021-10-28
Filing date: 2021-10-28
Publication date: 2022-01-14
Anticipated expiration: 2041-10-28
Also published as: CN113929337B

Abstract

The invention discloses ion-absorbing ceramsite and a preparation method thereof. The ion-absorbing ceramsite is mainly used in cement-based materials which are rich in chloride ions and sulfate ions in the surrounding environment and bring adverse effects on the structure of a cement matrix. When chloride ions and sulfate ions infiltrate into the cement-based material, the ion absorbent is released from the pores of the ceramsite and captures free ions, so that the adverse effect of the free ions on the cement-based material is reduced.

Description

Ion absorption ceramsite and preparation method thereof

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to ion absorption ceramsite and a preparation method thereof.

Background

The application of the cement-based material is also challenging, especially in the environment rich in chloride ions, sulfate ions and the like in the surrounding environments such as wharfs, cross-sea bridges, offshore wind power platforms and the like, and the ions can invade into the cement-based material to influence the durability and service life of the cement-based material.

Ceramsite is artificial lightweight aggregate, and generally undergoes chemical reaction under certain conditions to form a stable and hard solid phase. The artificial ceramsite has many excellent properties, such as low density, good freezing resistance, good softening coefficient and the like. The ceramsite has designability, and can be designed into ceramsite with different densities, different strengths and different water absorption rates, for example, the ceramsite designability is utilized to prepare a base material for concrete, and the base material can replace part of sandstone aggregates.

In the prior art, the cement-based material prepared by adopting the ceramsite is only in a conventional mixing and adding mode, but the ceramsite cement-based material prepared by the mode is forcibly stirred in the mixing process and can damage the material, so that the absorbent is released prematurely.

Disclosure of Invention

The invention aims to provide ion-absorbing ceramsite and a preparation method thereof. When corresponding ions in the cement-based material infiltrate, the free ions react with the packaging material, the membrane material is broken, the ion absorbent plays a role in absorbing the free ions, and the influence of the free ions on the cement-based material is reduced.

In order to achieve the purpose, the invention provides ion-absorbing ceramsite which comprises the following components in parts by weight: 10-30 parts of ion absorbent, 10-30 parts of film forming material and 50-100 parts of porous ceramsite; the ion absorbent is a chloride ion absorbent or a sulfate ion absorbent; the film forming material comprises polymer resin, emulsion, a diluent and a curing agent, wherein the mass ratio of the polymer resin to the emulsion is 1: 0.2-0.5, the dosage of the diluent is not less than 10% of the mass of the polymer resin, and the dosage of the curing agent is 0-25% of the mass of the polymer resin.

Further, the chloride ion absorbent is at least one of active cuprous oxide, active magnesium aluminum hydrotalcite, active aluminum oxide, calcium hydroxide, sodium metaaluminate, tricalcium aluminate, calcium aluminate powder, trisulfide calcium sulfoaluminate and monosulfide calcium sulfoaluminate.

Further, the sulfate ion absorbent is at least one of montmorillonite powder, hydrotalcite powder, ore powder, lime and polyaluminium chloride powder.

Further, the particle size of the ion absorbent particles is not more than 75 μm.

Further, the polymer resin is at least one of polyurethane, epoxy resin, acrylic resin, alkyd resin, hydroxy acrylic resin, vinyl resin and perchloroethylene resin.

Preferably, the polymer resin is an epoxy resin, a thermoplastic acrylic resin, and a hydroxyacrylic resin.

Further, the emulsion is styrene-acrylic emulsion, styrene-butadiene emulsion or acrylic emulsion.

Preferably, the emulsion is styrene-acrylic emulsion, styrene-butadiene emulsion, acrylate emulsion and acrylate polymer emulsion.

Further, the diluent is esters, ketones, alcohols or alcohol ethers; the curing agent is aliphatic diamine, aliphatic polyamine, aromatic polyamine, organic acid, acid anhydride or boron trifluoride and complex thereof.

The diluent is preferably one or more of acetone, butanone, methanol, ethanol, ethyl acetate, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether and xylene, and the curing agent is preferably polyamine.

Furthermore, the water absorption rate of the porous ceramsite is not less than 6%/h, and the cylinder pressure strength is not less than 3 MPa.

The preparation method of the ion absorption ceramsite is characterized by comprising the following steps of:

(1) crushing the porous ceramsite, sieving the crushed porous ceramsite by using a sieve, selecting the porous ceramsite with the fineness modulus of 2.1-3.7, and mixing the porous ceramsite with an ion absorbent under the negative pressure condition after ultrasonic vibration to prepare a ceramsite carrier;

(2) the preparation method comprises the steps of uniformly mixing the high polymer resin, the emulsion, the diluent and the curing agent to obtain a film-forming material, and coating the film-forming material on the surface of the ceramsite carrier.

Further, the thickness of a film layer coated by the film forming material is not more than 2 mm.

In summary, the invention has the following advantages:

1. the preparation method is simple, the cost of raw materials is low, and the porous ceramsite carrier has high strength and can completely resist the shear stress in the process of premixing the cement-based material;

2. because of the existence of the film-forming material, the ion-absorbing ceramsite can stably exist at the early stage of hydration of the cement-based material, so that the influence of an absorbent on the hydration, hydration products and performance of the cement-based material is avoided;

3. the ion-absorbing ceramsite prepared by the method can absorb free chloride ions or free sulfate ions in concrete, enhances the durability of a cement-based material, is simple in preparation method, and can realize large-scale industrial production.

Drawings

FIG. 1 is a schematic view of an ion-absorbing ceramsite prepared according to the present invention;

FIG. 2 is a schematic diagram showing changes in the concentration of chloride ions;

FIG. 3 is a schematic diagram showing changes in the concentration of sulfate ions;

FIG. 4 is a schematic diagram showing the change of concrete compressive strength under sulfate environment.

Detailed Description

The principles and features of this invention are described below in conjunction with embodiments, which are included to explain the invention and not to limit the scope of the invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1

The embodiment provides a preparation method of ion-absorbing ceramsite, which comprises the following steps:

(1) selecting ceramsite with the cylinder pressure strength of 4.5MPa and the water absorption of 10.4% for 1 hour, crushing, sieving, selecting porous ceramsite with the fineness modulus of 2.1, and ultrasonically vibrating and blowing for 3 min;

(2) weighing 60 parts of porous ceramsite and 30 parts of aluminum oxide, mixing and stirring under the negative pressure condition, wherein the aluminum oxide D₅₀The grain size is 45 mu m, the active aluminum oxide enters the pores of the ceramic grains, and the ceramic grains are taken out after the pores are filled with the aluminum oxide;

(3) and (3) taking 20 parts of epoxy resin, 7 parts of styrene-acrylic emulsion, 3 parts of diluent and 1.5 parts of curing agent, uniformly mixing, uniformly coating on the surface of the ceramsite prepared in the step (2) to form a thin film layer, and naturally drying to obtain the chloride ion absorbing ceramsite.

Wherein the diluent is prepared by uniformly mixing acetone and methanol according to the mass ratio of 1: 1; the curing agent is aliphatic diamine.

As shown in figure 1, the surface of the ceramsite absorbed by the chloride ions is smooth because the film-forming materials are resin and emulsion.

Example 2

(1) selecting ceramsite with the cylinder pressure strength of 6.4MPa and the water absorption of 7.4% for 1 hour, crushing, sieving, selecting porous ceramsite with the fineness modulus of 2.5, and ultrasonically vibrating and blowing for 3 min;

(2) weighing 60 parts of porous ceramsite and 30 parts of active sodium metaaluminate, mixing and stirring under the negative pressure condition, wherein the active sodium metaaluminate D₅₀The particle size is 34 mu m, the sodium metaaluminate enters the pores of the ceramsite, and the ceramsite is taken out after the pores are filled with the sodium metaaluminate;

(3) and (3) uniformly mixing 30 parts of dry alkyd resin, 15 parts of acrylic emulsion and 6 parts of diluent, uniformly coating the mixture on the surface of the ceramsite prepared in the step (2) to form a thin film layer, and naturally airing to obtain the chloride ion absorbing ceramsite.

Wherein, the diluent is xylene and ethanol mixed according to the mass ratio of 2:1, the curing agent is not needed in the embodiment, and the resin has the self-drying function (the same below).

Example 3

(1) selecting ceramsite with the cylinder pressure strength of 6.7MPa and the water absorption of 8.9% for 1 hour, crushing, sieving, selecting porous ceramsite with the fineness modulus of 3.0, and ultrasonically vibrating and blowing for 3 min;

(2) weighing 60 parts of porous ceramsite and 30 parts of active sodium metaaluminate, and mixing and stirring under the negative pressure condition, wherein the active sodium metaaluminate D₅₀The particle size is 25 mu m, the active sodium metaaluminate enters the pores of the ceramsite, and the ceramsite is taken out after the pores are filled with the sodium metaaluminate;

(3) and (3) uniformly mixing 30 parts of thermoplastic acrylic resin and 15 parts of diluent, uniformly coating the mixture on the surface of the ceramsite prepared in the step (2) to form a thin film layer, and naturally drying to obtain the chloride ion absorbing ceramsite.

Wherein the diluent is a mixture of ethanol, acetone and ethylene glycol monobutyl ether according to the mass ratio of 2:1: 1.

Example 4

(1) selecting ceramsite with the cylinder pressure strength of 6.7MPa and the water absorption of 9.8% for 1 hour, crushing, sieving, selecting porous ceramsite with the fineness modulus of 3.5, and ultrasonically vibrating and blowing for 3 min;

(2) weighing 70 parts of porous ceramsite and 30 parts of montmorillonite powder, mixing and stirring under a negative pressure condition to enable the active montmorillonite powder to enter pores of the ceramsite, wherein the active montmorillonite powder D50 is 30 mu m, and taking out the ceramsite after the pores are filled with the montmorillonite powder;

(3) and (3) uniformly mixing 20 parts of thermoplastic acrylic resin, 4 parts of acrylate polymer emulsion and 4 parts of diluent, uniformly coating the mixture on the surface of the ceramsite prepared in the step (2) to form a thin film layer, and naturally airing to obtain the sulfate ion absorption ceramsite.

The diluent is formed by mixing ethyl acetate and ethanol according to the mass ratio of 3: 1.

Example 5

(1) selecting ceramsite with the cylinder pressure strength of 7.7MPa and the water absorption of 8% for 1 hour, crushing, sieving, selecting porous ceramsite with the fineness modulus of 3.7, ultrasonically vibrating, and blowing for 3 min;

(2) weighing 50 parts of porous ceramsite and 20 parts of polyaluminium chloride powder, mixing and stirring under the negative pressure condition, wherein D of the polyaluminium chloride powder₅₀The grain size is 15 mu m, so that the aluminum chloride powder enters the pores of the ceramsite, and the ceramsite is taken out after the pores are filled with the aluminum chloride powder;

(3) and (3) uniformly mixing 25 parts of hydroxyl acrylic resin and 5 parts of diluent, uniformly coating the mixture on the surface of the ceramsite prepared in the step (2) to form a thin film layer, and naturally drying to obtain the sulfate ion absorption ceramsite.

The diluent is mixture of ethyl acetate, methanol and butanone according to the mass ratio of 1:1: 1.

Example 6

(1) selecting ceramsite with the cylinder pressure strength of 8.5MPa and the water absorption of 9.1% for 1 hour, crushing, sieving, selecting porous ceramsite with the fineness modulus of 2.1, and ultrasonically vibrating and blowing for 3 min;

(2) weighing 60 parts of porous ceramsite, 20 parts of tricalcium aluminate and 15 parts of mineral powder, mixing and stirring under a negative pressure condition, wherein the tricalcium aluminate D50 is 25 micrometers, the mineral powder D50 is 30 micrometers, enabling an ion absorbent to enter pores of the ceramsite, and taking out the ceramsite after the pores are filled with the ion absorbent;

(3) and (3) taking 15 parts of hydroxyl acrylic resin, 7.5 parts of butylbenzene emulsion and 1.8 parts of diluent, uniformly mixing, uniformly coating the mixture on the surface of the ceramsite prepared in the step (2) to form a thin film layer, and naturally airing to obtain the ceramsite absorbing chloride ions and sulfate ions.

Wherein the diluent is the mixture of ethyl acetate, methanol and butanone according to the mass ratio of 1:1: 1.

Example 7

(1) selecting ceramsite with the cylinder pressure strength of 7.5MPa and the water absorption of 8.7% for 1 hour, crushing, sieving, selecting porous ceramsite with the fineness modulus of 2.1, and ultrasonically vibrating and blowing for 3 min;

(2) weighing 60 parts of porous ceramsite, 15 parts of monothio-type calcium sulphoaluminate and 20 parts of hydrotalcite powder, mixing and stirring under a negative pressure condition, wherein the monothio-type calcium sulphoaluminate D50 is 35 mu m, the hydrotalcite powder D50 is 27 mu m, enabling an ion absorbent to enter pores of the ceramsite, and taking out the ceramsite after the pores are filled with the ion absorbent;

(3) and (3) taking 15 parts of vinyl resin, 6 parts of acrylate emulsion and 2.25 parts of diluent, uniformly mixing, uniformly coating the mixture on the surface of the ceramsite prepared in the step (2) to form a thin film layer, and naturally airing to obtain the ceramsite absorbed by chloride ions and sulfate ions.

The diluent is a mixture of xylene and styrene according to a mass ratio of 1:2, and the curing agent is methyl ethyl ketone peroxide.

Test example 1

The surface-treated ceramicites for concrete prepared in examples 1 to 7 were tested for the thickness of the coating layer and the alkali resistance thereof, wherein the thickness of the coating layer was measured using a metallographic microscope, and the results are shown in table 1 below.

TABLE 1 film formation thickness

As can be seen from Table 1, the film thickness of each example was less than 2mm, and the design requirements were satisfied.

The ion-absorbing ceramic granules prepared in examples 1 to 3 and 6 to 7 were tested for their absorption of chloride ions, and the method included the following steps:

(1) preparing an M solution of 0.05mol/L NaOH +0.35mol/L KOH, wherein the M solution can simulate a cement slurry pore solution, and the pH value of the solution is 12;

(2) adding 0.02mol/L NaCl solution into the M solution to obtain solution A, and adding 0.02mol/L NaSO into the M solution₄Obtaining a solution B;

(3) respectively placing the ion absorption ceramsite in the embodiments 1-3 and 6-7 in the solution A, and stirring at a low speed, wherein the stirring speed is not more than 20 r/min; after stirring for 4 hours, a sample of the solution A was taken, and the change of the chloride ion in the solution was monitored by a chloride ion concentration meter manufactured by Bell analysis instruments Ltd. The test result is shown in FIG. 2, the initial concentration of the solution test is 200 mg/L;

(4) respectively placing the ion absorption ceramsite obtained in the embodiment 4-7 in the solution B, and stirring at a low speed, wherein the stirring speed is not more than 20 r/min; after stirring for 4 hours, a sample of the solution B was taken, and the change of the chloride ion in the solution was monitored by a chloride ion concentration meter manufactured by Bell analysis instruments Ltd. The test results are shown in FIG. 3, where the initial concentration of the solution test was 200 mg/L.

As can be seen from FIG. 2, the chlorine ion concentration of each example is reduced continuously in a certain period of time, which indicates that the chlorine ion adsorbent reacts with the chlorine ions in the solution after the film-forming material is broken, so that the chlorine ion concentration is reduced.

Wherein, the concentration of the chloride ions begins to decrease in the examples 1 and 2 after about 400min, which indicates that the membrane material is broken and the chloride ion adsorbent begins to adsorb the chloride ions in the solution;

the chlorine ion concentration material begins to change at 500min in example 3, and compared with examples 1 and 2, the film-forming material in example 3 has no emulsion, which shows that the film-forming material prepared by resin alone has higher alkali resistance and the film material has later breaking time;

examples 6 and 7 are all ceramsite wrapped with chloride ion and sulfate ion absorbent, and it can be seen from the figure that the initial change time of the chloride ion concentration in example 7 is earlier than that in example 6, example 6 uses the film-forming material prepared by using the hydroxyacrylic resin and the styrene-butadiene emulsion, and example 7 uses the film-forming material prepared by using the vinyl resin and the acrylate emulsion, which shows that the film material of example 7 is earlier in rupture.

As can be seen from FIG. 3, the concentration of sulfate ions in each example gradually decreased with time, indicating that as time increased, the film-forming material broke and the sulfate ion adsorbent reacted with sulfate ions in the solution, decreasing free sulfate in the solution;

wherein, the ion concentration of the film forming materials of the embodiment 4 and the embodiment 6 starts to change at about 325min, which shows that the rupture time of the film forming materials of the embodiment 4 and the embodiment 6 is similar, mainly because the preferable resin and emulsion are used as the film forming materials;

the initial change time of the solution concentration in example 5 was about 420min, mainly because the film-forming material used only resin and no emulsion, and the film-breaking time was late, while in example 7, the concentration of sulfuric acid and ion had already decreased to about 180mg/L at 200min, mainly because the film-forming material broke earlier.

Test example 2

From the test results of test example 1, it can be seen that by changing the composition of the film-forming material, the film-forming material can be ruptured in a strong alkali solution at different times, releasing the ion absorbent, and reacting with free ions, thereby achieving the design purpose. In order to further verify the effect of the ceramsite in the real cement-based material, the ceramsite prepared in examples 1 to 7 is used as concrete sand, and the compounding ratio of the ceramsite is shown in the following table 2.

TABLE 2C 30 concrete mixing ratio/kg/m³

The concrete doped with the ion absorption ceramsite in the examples 1-3 and 6-7 is tested for compressive strength and chloride ion permeability resistance after being hydrated for 7 days, the test piece is formed, tested and calculated in strength according to GB/T GB/T50107-2010 concrete strength detection and evaluation Standard, the electric flux of the concrete is tested according to 7.2 in GB/T50082-2009 test method Standard for testing the long-term performance and durability of the common concrete, and the result is shown in Table 3, wherein the control group is a test piece without the ion absorption ceramsite.

TABLE 3C 30 concrete compressive Strength and electric flux

As can be seen from Table 3, compared with the control group, the strength of the concrete after the ion absorption ceramsite of the examples is added is changed, and the strength of the concrete of some examples is reduced and the strength of some examples is improved compared with the control group. For the electric flux of the concrete, compared with a control group, the electric flux of the sample doped with the ion absorbing ceramsite is reduced, namely the capacity of chloride ions passing through the concrete is reduced. The combination of the film material, the ion absorbent and the performance analysis shown in table 2 shows that the strength of the concrete in examples 1, 2, 6 and 7 is reduced compared with that of the control group, the strength of example 7 is obviously reduced, the strength of example 3 is obviously improved, the main reason is that the film forming material causes adverse effect on the mechanical property of the concrete, and the ion absorbing ceramsite which is singly doped with the thermoplastic acrylic resin as the film forming material can improve the strength of the concrete.

Test example 3

The sulfate corrosion resistance of the concrete doped with the ion-absorbing ceramsite in examples 4-7 after 7 days of hydration was tested, and the test method was performed according to GB/T50082-2009 test method Standard for Long-term Performance and durability of ordinary concrete, and the results are shown in FIG. 4.

As can be seen from FIG. 4, the compressive strength of the concrete samples is continuously reduced along with the increase of the number of times of circulation, and compared with the concrete samples of the reference group, the reduction rate of the compressive strength of the concrete doped with the ion-absorbing ceramsite is gentle after the concrete is circulated for a certain number of times. Example 4 begins to change the compressive strength gradually after 20 cycles, which shows that the ion absorbent absorbs free ions after the membrane material is broken, and the influence on the compressive strength of the concrete is weakened. Example 5 did not weaken until 60 cycles, primarily because the film-forming material had better alkali resistance and the time to rupture was later, and similarly, the changes in examples 6 and 7 were due to the time to begin to slow down the compressive strength of the film-forming material, which was different due to the alkali resistance of the film-forming material.

While the present invention has been described in detail with reference to the illustrated embodiments, it should not be construed as limited to the scope of the present patent. Various modifications and changes may be made by those skilled in the art without inventive step within the scope of the appended claims.

Claims

1. The ion-absorbing ceramsite is characterized by comprising the following components in parts by weight: 10-30 parts of ion absorbent, 10-30 parts of film forming material and 50-100 parts of porous ceramsite; the ion absorbent is a chloride ion absorbent and/or a sulfate ion absorbent; the film forming material comprises polymer resin, emulsion, a diluent and a curing agent, wherein the mass ratio of the polymer resin to the emulsion is 1: 0.2-0.5, the dosage of the diluent is not less than 10% of the mass of the polymer resin, and the dosage of the curing agent is 0-25% of the mass of the polymer resin.

2. The ion-absorbing ceramsite of claim 1, wherein said chloride ion absorbent is at least one of activated cuprous oxide, activated magnesium aluminum hydrotalcite, activated aluminum oxide, calcium hydroxide, sodium metaaluminate, tricalcium aluminate, calcium aluminate powder, calcium sulfoaluminate trisulfide, and calcium sulfoaluminate monosulfide.

3. The ion-absorbing ceramsite of claim 1, wherein the sulfate ion absorbent is at least one of montmorillonite powder, hydrotalcite powder, mineral powder, lime, and polyaluminium chloride powder.

4. The ion-absorbing ceramic particle of claim 1, wherein the polymeric resin is at least one of polyurethane, epoxy, acrylic, alkyd, hydroxyacrylic, vinyl, and perchloroethylene.

5. The ion-absorbing ceramsite of claim 1, wherein said emulsion is a styrene-acrylic emulsion, a styrene-butadiene emulsion, or an acrylic emulsion.

6. The ion-absorbing ceramsite of claim 1, wherein the diluent is an ester, a ketone, an alcohol, or an alcohol ether; the curing agent is aliphatic diamine, aliphatic polyamine, aromatic polyamine, organic acid, acid anhydride or boron trifluoride and a complex compound thereof.

7. The ion-absorbing ceramsite of claim 1, wherein said porous ceramsite has a water absorption of not less than 6%/h and a cylinder pressure strength of not less than 3 MPa.

8. The method for preparing ion-absorbing ceramsite of claims 1-7, which comprises the following steps:

9. The method for preparing ion-absorbing ceramsite of claim 8, wherein the thickness of the film coated with the film-forming material is not more than 2 mm.