CN110015853B

CN110015853B - Ultrahigh-toughness geopolymer and preparation method thereof

Info

Publication number: CN110015853B
Application number: CN201910062137.2A
Authority: CN
Inventors: 郭晓潞; 杨君奕
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2019-01-23
Filing date: 2019-01-23
Publication date: 2021-07-02
Anticipated expiration: 2039-01-23
Also published as: CN110015853A

Abstract

The invention provides a geopolymer with ultrahigh toughness and a preparation method thereof, wherein the geopolymer with ultrahigh toughness comprises steel slag, fly ash, a composite exciting agent and a toughening agent; wherein, the addition amount of the composite exciting agent is 5-8% of the total mass of the steel slag and the fly ash, and the addition amount of the toughening agent is 1 +/-0.5% of the total volume of the steel slag and the fly ash; the method utilizes the steel slag and the fly ash to prepare the ultrahigh-toughness geopolymer, thereby not only expanding the resource utilization means of the steel slag, but also realizing the reduction, the resource utilization and the high-value resource utilization of the steel slag and creating a new way for protecting the ecological environment; on the other hand, compared with the pure fly ash based ultra-high toughness geopolymer, the compression strength and the tensile strength of the geopolymer are greatly improved, so that the performance is improved; although the geopolymer has less greenhouse gas emission and is an environment-friendly cementing material with low carbon emission, the toughness of the geopolymer is poor, and the geopolymer with ultrahigh toughness is obtained after the toughening agent is added, so that the toughness of the geopolymer is effectively improved.

Description

Ultrahigh-toughness geopolymer and preparation method thereof

Technical Field

The invention belongs to the technical field of resource utilization of building materials and solid wastes, and particularly relates to an ultrahigh-toughness geopolymer and a preparation method thereof.

Background

In less than 200 years, the Portland cement is widely applied and becomes an indispensable material foundation in modern human civilization construction. However, portland cement is a cementitious material with high energy and resource consumption. In addition, a large amount of harmful gas such as NO is emitted during the cement production process_X、SO₂And dust and the like. Therefore, the development of a new type of cement material with low energy consumption and high benefit, which can replace or exceed portland cement, is an inherent need of social development.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims at widening the way of recycling steel slag, takes fly ash and steel slag as main raw materials to be mixed, and prepares a novel environment-friendly inorganic cementing material, namely a polymer with ultrahigh toughness under the combined action of a composite exciting agent and a toughening agent.

The second object of the present invention is to provide a process for producing the above ultra-high toughness polymer.

In order to achieve the above purpose, the solution of the invention is as follows:

an ultra-high toughness polymer comprising the following components:

10-30 wt% of steel slag;

70-90 wt% of fly ash.

Further, the specific surface area of the steel slag is 350-450m²/kg。

Further, the specific surface area of the fly ash is 300-400m²/kg。

Further, the ultra-high toughness polymer further comprises: compounding an excitant and a toughening agent; wherein the addition amount of the composite exciting agent is 5-8% of the total mass of the steel slag and the fly ash, and Na in the composite exciting agent₂The content of O is subject to the standard; the addition amount of the toughening agent is 1 +/-0.5 percent of the total volume of the steel slag and the fly ash.

Further, the compound excitant is prepared by sodium silicate and sodium hydroxide, and the adding amount of the sodium hydroxide is calculated according to the following formula:

wherein G is₁Is the mass of sodium silicate, and N is Na in the sodium silicate₂Content of O, M₁Initial modulus, M, for sodium water glass₂P is the purity of sodium hydroxide, which is the preparation modulus of the compound excitant required by the experiment.

Further, the modulus of the compound activator is 1.5 +/-0.1.

Further, the toughening agent is polyvinyl alcohol fiber.

Furthermore, the elastic modulus of the toughening agent is 40-45Gpa, and the ultimate elongation is 6-10%.

Further, the water-solid ratio of the ultra-high toughness geopolymer is 0.30-0.35, wherein the water in the water-solid ratio comprises the water content and the external water content of the sodium water glass solution in the composite exciting agent, and the solid in the water-solid ratio comprises the sum of the mass of the steel slag and the mass of the fly ash.

A preparation method of the ultrahigh-toughness geopolymer comprises the following steps:

(1) mixing the steel slag and the fly ash to obtain a mixture;

(2) adding composite exciting agent and toughening agent into the mixture to react, and coagulating and hardening to obtain the polymer with ultrahigh toughness.

Preferably, the ultra-high toughness polymer has a water-to-solid ratio of 0.30 to 0.35.

Due to the adoption of the scheme, the invention has the beneficial effects that:

firstly, the ultrahigh-toughness geopolymer is prepared by using the steel slag and the fly ash, so that on one hand, a resource utilization means of the steel slag is expanded, the reduction, the resource utilization and the high-value resource utilization of the steel slag are realized, the problem of pollution caused by site occupation due to waste stacking is solved, and a new way is created for protecting the ecological environment; on the other hand, compared with the pure fly ash based ultra-high toughness geopolymer, the compression strength and the tensile strength of the ultra-high toughness geopolymer are greatly improved, so that the performance is improved.

Secondly, although the geopolymer has less greenhouse gas emission and is an environment-friendly cementing material with low carbon emission, the toughness of the geopolymer is poor, and the ultra-high-toughness geopolymer is obtained after the polyvinyl alcohol fiber is added, so that the toughness of the geopolymer is effectively improved.

Drawings

FIG. 1 is a graph showing the performance results of examples of the present invention and comparative examples. (Tensile strain on abscissa and Tensile strength on ordinate.)

Detailed Description

The invention provides a polymer with ultrahigh toughness and a preparation method thereof.

< ultra high tenacity Polymer >

An ultra-high toughness polymer comprises the following components:

10-30 wt% of steel slag;

70-90 wt% of fly ash.

The contents of the steel slag and the fly ash can be combined at will as long as the sum of the mass of the steel slag and the fly ash is 100 percent.

Specifically, the main components of the steel slag and fly ash are shown in table 1.

TABLE 1 composition of steel slag and fly ash

Wherein the steel slag is the waste slag generated in the steel-making process, and the specific surface area of the steel slag can be 350-450m²Kg, preferably 400m²/kg。

The steel slag is waste slag discharged by extracting impurities such as silicon oxide, aluminum oxide and the like in pig iron by using limestone as a fusing agent in a steel making process, is classified according to steel furnace types discharged by the steel slag, and is mainly classified into converter slag, flat furnace slag and electric furnace slag, wherein the discharge amount of the converter slag is the largest. The steel slag is a byproduct in the steel making process, about 10-20% of the steel slag is generally generated when 1 ton of crude steel is produced, and if the steel slag cannot be effectively recycled, a large amount of steel slag is accumulated for a long time, so that land resources are occupied, and a serious environment pollution problem is caused. Therefore, the steel slag and the fly ash are utilized to prepare the ultrahigh-toughness geopolymer and perform strengthening and toughening, so that the mechanical property of the ultrahigh-toughness geopolymer is improved, and the reduction, resource utilization and high-value resource utilization of the steel slag are realized.

The fly ash is the second-level fly ash in a power plant, the fineness is measured by a standard sieve with the particle size of 45 mu m, the sieve residue is not more than 20 percent, and the specific surface area of the fly ash can be 400m plus 300-²/kg, preferably 350m²/kg。

The fly ash is solid waste generated in thermal power plants, metallurgy, chemical industry and other industries, and abundant coal resources in China still dominate thermal power generation in the power generation industry. The electric coal accounts for more than 50% of the coal consumption in China, and the utilization form of the coal resource can be maintained for a long time. A large amount of fly ash is generated in the coal burning process, accounting for 15-40% of the mass of raw coal, and the fly ash becomes one of the most industrial wastes in accumulated storage capacity and cultivated land occupation in China.

In recent years, China always pays attention to the resource utilization of the fly ash, and has mature application in the aspects of building materials, construction, road building, town returning, agriculture and the like, but the resource utilization of the steel slag is relatively lacked, so that the invention utilizes the industrial waste fly ash and the waste steel slag as main raw materials to prepare the ultrahigh-toughness polymer, thereby not only widening the resource utilization way of the steel slag, but also lightening the environmental burden, reducing the cost and reducing the resource consumption, thereby meeting the requirements of energy conservation and emission reduction and meeting the national conditions of China.

In fact, the ultra-high tenacity polymer also comprises: compounding an excitant and a toughening agent; wherein the addition amount of the composite exciting agent is 5-8% of the total mass of the steel slag and the fly ash, and Na in the composite exciting agent₂The content of O is subject to the standard; the addition amount of the toughening agent is 1 +/-0.5 percent of the total volume of the steel slag and the fly ash.

The compound excitant is prepared by sodium silicate and sodium hydroxide, and the addition amount of the sodium hydroxide is calculated according to the following formula:

The modulus M of the composite activator is 1.5 +/-0.1, wherein M represents SiO₂Mole number of (3) and Na₂Ratio of moles of O (M ═ n (SiO)₂)/n(Na₂O))。

Specifically, the initial modulus of the sodium water glass was 2.25, the solid content was 43.74%, and the sodium water glass was adjusted using sodium hydroxide (NaOH) to obtain a certain modulus (M ═ n (SiO) (chemical oxygen demand (SiO)) of₂)/n(Na₂O)) a composite activator. The indices of 100g of sodium water glass before and after conditioning are shown in Table 2.

TABLE 2 sodium silicate modulus before and after adjustment of the content of the main component

Wherein, the flexibilizer is polyvinyl alcohol fiber, the elastic modulus is 40-45Gpa, and the ultimate elongation is 6-10%.

The polyvinyl alcohol fibers used in the present invention are Kuraray-II RECS-15 type polyvinyl alcohol fibers manufactured by Kuraray of Japan.

Polyvinyl alcohol fibers (PVA fibers) are obtained by preparing a polyvinyl alcohol raw material into tows by adopting advanced technical means such as wet spinning, dry spinning and the like, and cutting the tows into fibers with different lengths.

Further, the water-solid ratio of the ultrahigh-toughness geopolymer is 0.30-0.35, wherein the water in the water-solid ratio comprises the water content and the external water content of the sodium water glass solution in the composite exciting agent, namely when the water-solid ratio of the system is controlled to be 0.30-0.35, the insufficient water content is complemented by the external water content except the water content of the sodium water glass solution; the solid in the water-solid ratio comprises the sum of the mass of the steel slag and the mass of the fly ash.

< method for producing ultrahigh-toughness Polymer >

The preparation method of the ultrahigh-toughness geopolymer comprises the following steps:

(1) mixing the steel slag and the fly ash to obtain a mixture;

Wherein, the water-solid ratio of the ultra-high toughness polymer can be 0.30-0.35, preferably 0.35; the strain is more than 3%.

The present invention will be further described with reference to the following examples.

Example 1:

the preparation method of the ultra-high toughness geopolymer (FASS14) of this example includes the following steps:

(1) mixing the steel slag and the fly ash to obtain a mixture;

(2) the compound exciting agent and the polyvinyl alcohol fiber are added into the mixture to be mixed, molded and demoulded to obtain the polymer with ultrahigh toughness, and the performance of the polymer is detected from the wet culture to the measuring age, wherein the performance data is shown in Table 8.

In fact, the ultra-high toughness polymer has a water-to-solid ratio of 0.35.

Wherein the content of the steel slag is 14 wt%, and the specific surface area is 400m²Per kg; the mixing amount of the fly ash is 86wt percent, and the specific surface area is 350m²And/kg (the sum of the mass of the steel slag and the mass of the fly ash is 100 percent).

The mixing amount (external mixing) of the composite excitant is 6 wt%, and the modulus is 1.5; the volume doping amount (external doping) of the polyvinyl alcohol fiber is 1 percent.

Specifically, the composite activator is prepared by mixing sodium silicate and sodium hydroxide, and the modulus M is controlled to be 1.5, wherein the solid content of the sodium silicate is 43.74%, and actually, Na₂O content of 21.04%, SiO₂In an amount of 27.46%, H₂The O content was 51.50%, the purity of sodium hydroxide was 96%, and the amount of sodium hydroxide added was 25.6 g.

Actually, the compounding ratio of the ultra-high toughness polymer of this example is shown in Table 3.

TABLE 3 blending ratio of the ultra-high toughness geopolymer (FASS14) of this example

Fly ash/g	Steel slag/g	Sodium water glass/g	Water/g	PVA fiber/%)
					600	100	277.41	70.56	1

Example 2:

the preparation method of the ultra-high toughness geopolymer (FASS21) of this example includes the following steps:

(1) mixing the steel slag and the fly ash to obtain a mixture;

In fact, the ultra-high toughness polymer has a water-to-solid ratio of 0.35.

Wherein the steel slag content is 21 wt%, and the specific surface area is 400m²Per kg; the mixing amount of the fly ash is 79wt percent, and the specific surface area is 350m²And/kg (the sum of the mass of the steel slag and the mass of the fly ash is 100 percent).

Actually, the compounding ratio of the ultra-high toughness polymer of this example is shown in Table 4.

TABLE 4 blending ratio of the ultra-high toughness geopolymer (FASS21) of this example

Fly ash/g	Steel slag/g	Sodium water glass/g	Water/g	PVA fiber/%)
					550	150	277.41	70.56	1

Example 3:

the preparation method of the ultra-high toughness geopolymer (FASS28) of this example includes the following steps:

(1) mixing the steel slag and the fly ash to obtain a mixture;

In fact, the ultra-high toughness polymer has a water-to-solid ratio of 0.35.

Wherein the steel slag content is 28 wt%, and the specific surface area is 400m²Per kg; the mixing amount of the fly ash is 72wt percent, and the specific surface area is 350m²And/kg (the sum of the mass of the steel slag and the mass of the fly ash is 100 percent).

Actually, the compounding ratio of the ultra-high toughness polymer of this example is shown in Table 5.

TABLE 5 blending ratio of the ultra-high toughness geopolymer (FASS28) of this example

Fly ash/g	Steel slag/g	Sodium water glass/g	Water/g	PVA fiber/%)
					500	200	277.41	70.56	1

Comparative example 1:

the preparation method of the pure-fly-ash-based ultra-high-toughness geopolymer (FA) of the comparative example comprises the following steps:

the composite exciting agent and the polyvinyl alcohol fiber are added into the fly ash to be mixed, molded and demoulded to obtain the pure fly ash-based ultrahigh-toughness polymer, and the performance of the polymer is detected from wet-culture to the measurement age, wherein the performance data is shown in Table 8.

Wherein the mixing amount of the fly ash is 100 wt%.

In fact, the compounding ratio of the pure fly ash based ultra high toughness polymer of this comparative example is shown in Table 6.

TABLE 6 blending ratio of pure fly ash based ultra high tenacity geopolymer (FA) of this comparative example

Fly ash/g	Steel slag/g	Sodium water glass/g	Water/g	PVA fiber/%)
					700	0	277.41	70.56	1

Comparative example 2:

the preparation method of the fly ash/steel slag-based polymer (FASS21-N) of the comparative example comprises the following steps:

(1) mixing the steel slag and the fly ash to obtain a mixture;

(2) and adding a composite exciting agent into the mixture, mixing, molding and demolding to obtain the fly ash/steel slag-based polymer, carrying out wet-curing to the determination age, and detecting the performance, wherein the performance data is shown in Table 8.

The mixing amount (external mixing) of the composite exciting agent is 6 wt%, and the modulus is 1.5.

In fact, the blending ratio of the fly ash/steel slag-based polymer of this comparative example is shown in Table 7.

TABLE 7 blending ratio of fly ash/steel slag-based polymer (FASS21-N) of this comparative example

Fly ash/g	Steel slag/g	Sodium water glass/g	Water/g	PVA fiber/%)
					550	150	277.41	70.56	0

TABLE 8 Performance data for examples and comparative examples

As can be seen from Table 8 and FIG. 1, the compressive strength and ultimate tensile strength (ultimate tensile strength is the strength at break of the test block) of the ultra-high toughness polymer of each example are significantly improved compared with the pure fly ash based ultra-high toughness polymer of comparative example 1, which indicates that the addition of steel slag in the invention can significantly improve the performance of the ultra-high toughness polymer, and thus a new method and a new way are provided for the resource utilization of the steel slag; the example 2 has a significant improvement in ultimate tensile strength and a multi-crack phenomenon, compared with the comparative example 2, and shows that the addition of PVA makes it possible to realize an ultra-high-toughness polymer having a strain higher than 3%.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. It will be readily apparent to those skilled in the art that various modifications to these embodiments and the generic principles defined herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments. Those skilled in the art should appreciate that many modifications and variations are possible in light of the above teaching without departing from the scope of the invention.

Claims

1. The preparation method of the polymer with ultrahigh toughness is characterized by comprising the following steps:

(1) mixing the steel slag and the fly ash to obtain a mixture;

(2) adding a composite exciting agent and polyvinyl alcohol fibers into the mixture, mixing, molding and demolding to obtain the ultra-high-toughness polymer, and carrying out wet-culture to a determination age to detect the performance of the polymer, wherein the performance data is as follows:

the 7d compressive strength is 12.38MPa, and the 7d ultimate tensile strength is 1.32 MPa;

the mixing ratio of the ultra-high toughness polymer is as follows: 550g of fly ash, 150g of steel slag, 277.41g of composite exciting agent, 70.56g of water and 1% of PVA fiber doping volume;

wherein the specific surface area of the steel slag is 400m²Per kg, specific surface area of fly ash 350m²The modulus of elasticity of the polyvinyl alcohol fiber is 40-45GPa, the ultimate elongation is 6-10%, the composite exciting agent is prepared by mixing sodium silicate and sodium hydroxide, the solid content of the sodium silicate is 43.74%, the purity of the sodium hydroxide is 96%, the doping amount of the sodium hydroxide is 25.6g, the modulus M of the prepared composite exciting agent is 1.5, and the Na content of the composite exciting agent is 1.5₂O content of 21.04%, SiO₂In an amount of 27.46%, H₂The O content was 51.50%.