阅读说明：本技术 一种煤矸石基掺合料及其制备方法 (Coal gangue-based admixture and preparation method thereof ) 是由 祝小靓 高育欣 郭照恒 王军 赖航 宋文静 程宝军 于 2021-01-07 设计创作，主要内容包括：本发明公开了一种煤矸石基掺合料及其制备方法,所述制备方法包括以下步骤：以80-90份煤矸石为原料,将其预磨成粉,然后将煤矸石粉与5-15份氧化钙和5-15份石膏进行湿混、蒸养、煅烧,随后将煅烧后的产物冷却后与3-6份硅烷偶联剂进行共同粉磨,最后将共同粉磨后的产物与15-20份粉煤灰和5-10份石灰石粉进行混合得到所述煤矸石基掺合料。本发明制备得到的煤矸石基掺合料,煤矸石占比≥70％,制备的砂浆流动度比≥97％,活性≥85％,掺加此掺合料的混凝土其坍落度、扩展度等和易性与普通混凝土无异。能够满足不同施工要求的混凝土使用,适合大规模推广应用,具有显著的经济效益和社会效益。(The invention discloses a coal gangue-based admixture and a preparation method thereof, wherein the preparation method comprises the following steps: the gangue-based admixture is prepared by using 80-90 parts of gangue as a raw material, pre-grinding the gangue into powder, wet mixing, steaming and calcining gangue powder, 5-15 parts of calcium oxide and 5-15 parts of gypsum, cooling a calcined product, then co-grinding the cooled calcined product and 3-6 parts of silane coupling agent, and finally mixing the co-ground product with 15-20 parts of fly ash and 5-10 parts of limestone powder to obtain the gangue-based admixture. The coal gangue content of the coal gangue-based admixture prepared by the invention is more than or equal to 70 percent, the fluidity ratio of the prepared mortar is more than or equal to 97 percent, the activity is more than or equal to 85 percent, and the workability of the concrete doped with the admixture is the same as that of the common concrete in slump, expansion and the like. The concrete can meet the use requirements of concrete with different construction requirements, is suitable for large-scale popularization and application, and has remarkable economic and social benefits.)

1. The coal gangue-based admixture is characterized by comprising the following components in percentage by mass: 80-90 parts of coal gangue, 5-15 parts of calcium oxide, 5-15 parts of gypsum, 3-6 parts of silane coupling agent, 15-20 parts of fly ash and 5-10 parts of limestone powder.

2. The gangue-based admixture as defined in claim 1, wherein the gypsum is one or more of anhydrite, hemihydrate gypsum, dihydrate gypsum, phosphogypsum and desulfurized gypsum.

3. The gangue-based admixture as defined in claim 1, wherein the silane coupling agent is one or more of isobutyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, aminopropyltriethoxysilane, propyltrimethoxysilane.

4. The preparation method of the coal gangue-based admixture is characterized by comprising the following steps: the gangue-based admixture is prepared by pre-grinding gangue serving as a raw material into powder, then dry-mixing, wet-mixing, steaming and calcining 80-90 parts of gangue powder, 5-15 parts of calcium oxide and 5-15 parts of gypsum, then cooling a calcined product, then jointly grinding the cooled calcined product and 3-6 parts of silane coupling agent, and finally mixing the jointly ground product with 15-20 parts of fly ash and 5-10 parts of limestone powder to obtain the gangue-based admixture.

5. The method of claim 4, wherein the wet mixing of the gangue powder with the calcium oxide and gypsum is performed at a water-to-powder ratio of 0.1-0.25 for 5-20 minutes.

6. The method of claim 5, wherein the gangue powder is wet mixed with the calcium oxide and gypsum in the form of a spray.

7. The method of claim 4, wherein the gangue powder is steamed at 70-90 ℃ for 4-8 hours with calcium oxide and gypsum.

8. The method for preparing the gangue-based admixture as defined in claim 4, wherein the gangue powder, calcium oxide and gypsum are calcined at 600-900 ℃ for 1-4 hours.

9. The method of claim 4, wherein the steamed gangue powder is pelletized in a pelletizer before the gangue powder is calcined with calcium oxide and gypsum, and then the pelletized mixture is calcined.

10. The method for preparing the gangue-based admixture as defined in any one of claims 4 to 9, wherein the gangue has a pre-pulverized specific surface area of 200m or more²Per kg; the specific surface area of the product ground together with the silane coupling agent is more than or equal to 500m²Per kg; the specific surface area of the fly ash is more than or equal to 400m²/kg。

Technical Field

The invention relates to the technical field of building materials, in particular to a coal gangue-based admixture and a preparation method thereof.

Background

The coal gangue contains a large amount of silicon-aluminum minerals, namely SiO₂And Al₂O₃The contents of the waste water can reach 30-60% and 15-40% respectively, and the waste water is a resource for 'misplacing'. The coal gangue used as the concrete admixture can effectively reduce the stockpiling of the coal gangue on the one hand, and reduce the consumption of cement on the other hand, thereby realizing sustainable development. The activated coal gangue has good economic, social and environmental benefits when being applied to the engineering fields of construction, traffic and the like.

From the chemical composition, the coal gangue has high SiO₂And Al₂O₃The low calcium composition of (A) and the high calcium composition of the portland cement clinker can form complementation, thereby effectively improving the performance of the portland cement. However, the use of the unactivated coal gangue which is not treated by any method as a concrete admixture directly brings adverse effects on the performance of concrete. The coal gangue has a porous structure, so when the coal gangue is used as an admixture, a part of mixing water can be absorbed, the working performance of concrete is affected, and negative effects on workability are generated; in addition, in order to increase the blending amount of the coal gangue and reduce the influence of the coal gangue on the mechanical property of the concrete, the activity of the coal gangue is also required to be further improved.

In the existing research on coal gangue-based admixtures, the coal gangue-based admixtures are mostly compounded with CaO, gypsum and the like, and the coal gangue-containing composite materials are calcined to improve the activity, for example, CN 102167532A (a method for preparing a concrete admixture by a concrete admixture and calcining coal gangue) proposes a process for mixing and calcining coal gangue, limestone, gypsum and fluorite to prepare a high-activity coal gangue composite admixture, but the preparation method has larger water demand. CN 106316178A (mineral admixture I-grade composite fly ash for concrete and manufacturing method thereof) is mixed and ground by using burnt-through coal gangue, blast furnace slag, converter slag and crushed silica, the prepared I-grade composite fly ash has low water demand but unknown activity, and the coal gangue accounts for a small proportion, thus having small contribution to the resource utilization of the coal gangue.

Disclosure of Invention

Aiming at the problems, the invention aims to provide the coal gangue-based admixture and the preparation method thereof.

The technical scheme of the invention is as follows:

on the one hand, the coal gangue-based admixture comprises the following components in percentage by mass: 80-90 parts of coal gangue, 5-15 parts of calcium oxide, 5-15 parts of gypsum, 3-6 parts of silane coupling agent, 15-20 parts of fly ash and 5-10 parts of limestone powder.

Preferably, the gypsum is one or more of anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, phosphogypsum and desulfurization gypsum.

Preferably, the silane coupling agent is one or more of isobutyl triethoxysilane, vinyl trimethoxysilane, aminopropyltriethoxysilane and propyltrimethoxysilane.

On the other hand, the preparation method of the coal gangue-based admixture comprises the following steps: the gangue-based admixture is prepared by pre-grinding gangue serving as a raw material into powder, then dry-mixing, wet-mixing, steaming and calcining 80-90 parts of gangue powder, 5-15 parts of calcium oxide and 5-15 parts of gypsum, then cooling a calcined product, then jointly grinding the cooled calcined product and 3-6 parts of silane coupling agent, and finally mixing the jointly ground product with 15-20 parts of fly ash and 5-10 parts of limestone powder to obtain the gangue-based admixture.

Preferably, when the gangue powder, the calcium oxide and the gypsum are wet-mixed, the wet-mixing is carried out for 5 to 20 minutes at a water-powder ratio of 0.1 to 0.25.

Preferably, the gangue powder is wet-mixed with the calcium oxide and the gypsum in the form of spray.

Preferably, the coal gangue powder, calcium oxide and gypsum are steamed at 70-90 ℃ for 4-8 hours.

Preferably, the coal gangue powder, calcium oxide and gypsum are calcined at the temperature of 600-900 ℃ for 1-4 hours.

Preferably, before the coal gangue powder, the calcium oxide and the gypsum are calcined, the steamed product is pelletized in a pelletizer, and then the pelletized mixture is calcined.

Preferably, the specific surface area of the coal gangue after pre-grinding is more than or equal to 200m²Per kg; the specific surface area of the product ground together with the silane coupling agent is more than or equal to 500m²Per kg; the specific surface area of the fly ash is more than or equal to 400m²/kg。

The invention has the beneficial effects that:

the invention mixes the coal gangue powder with calcium oxide and gypsum, carries out autoclaved curing in advance, can erode quartz and feldspar through hydrothermal alteration process, and the alkalinity of the calcium oxide can cause Al-O band fracture and Silicon (SiO) enrichment₂·nH₂O) is formed. The silane coupling agent is used for modifying the surface of the coal gangue after high-temperature calcination and activation, and the coal gangue is mixed with the fly ash and the limestone, so that the adverse effects of the coal gangue-based admixture on the workability of the concrete are eliminated by utilizing the modification of the silane coupling agent on the surface of the coal gangue and the ball effect, lubricity and particle accumulation effect of the fly ash and the limestone, the activity and the mixing amount of the coal gangue are improved, and the use of the concrete with different construction requirements can be met.

Detailed Description

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

It should be noted that, in the present application, the embodiments and the technical features of the embodiments may be combined with each other without conflict.

It is noted that, unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

Example 1

A preparation method of a coal gangue-based admixture comprises the following steps:

step 1: pre-grinding coal gangue, dry-mixing 80 parts of coal gangue powder, 5 parts of calcium oxide and 15 parts of gypsum for 20 minutes, and wet-mixing the powder for 20 minutes in a water-powder ratio of 0.15 by using tap water in a spraying manner; the mixed materials are steamed and cured for 8 hours at the temperature of 80 ℃, then taken out to be pelletized in a pelletizer, the spherical mixture is calcined for 4 hours at the temperature of 800 ℃, and taken out to be naturally cooled at room temperature.

Step 2: grinding the product obtained in the step 1 and 3 parts of silane coupling agent in a grinding machine for 25 minutes until the specific surface area reaches 600m²/kg。

And step 3: the product of step 2 is mixed with 15 parts of a mixture having a specific surface area of 400m²Per kg of fly ash and 5 parts of 700m specific surface area²And (3) carrying out dry mixing on/kg limestone powder for 20 minutes to obtain the coal gangue-based admixture.

Example 2

A preparation method of a coal gangue-based admixture comprises the following steps:

step 1: pre-grinding coal gangue, dry-mixing 80 parts of coal gangue powder, 5 parts of calcium oxide and 15 parts of gypsum for 5-20 minutes, and wet-mixing the powder for 20 minutes in a water-powder ratio of 0.15 by using tap water in a spraying manner; the mixed materials are steamed and cured for 8 hours at the temperature of 80 ℃, then taken out to be pelletized in a pelletizer, the spherical mixture is calcined for 4 hours at the temperature of 800 ℃, and taken out to be naturally cooled at room temperature.

Step 2: grinding the product obtained in the step 1 and 5 parts of silane coupling agent in a grinding machine for 30 minutes until the specific surface area reaches 650m²/kg。

And step 3: the product of step 2 is mixed with 20 parts of a mixture having a specific surface area of 500m²Per kg of fly ash and 10 parts of fly ash with a specific surface area of 800m²And (3) carrying out dry mixing on/kg limestone powder for 20 minutes to obtain the coal gangue-based admixture.

Example 3

Step 1: pre-grinding coal gangue, dry-mixing 80 parts of coal gangue powder, 5 parts of calcium oxide and 15 parts of gypsum for 5-20 minutes, and wet-mixing the powder for 20 minutes in a water-powder ratio of 0.15 by using tap water in a spraying manner; the mixed materials are steamed and cured for 8 hours at the temperature of 80 ℃, then taken out to be pelletized in a pelletizer, the spherical mixture is calcined for 4 hours at the temperature of 800 ℃, and taken out to be naturally cooled at room temperature.

Step 2: grinding the product obtained in the step 1 and 6 parts of silane coupling agent in a grinding machine for 25 minutes until the specific surface area reaches 600m²/kg；

And step 3: the product of step 2 is admixed with 20 parts of a specific surface area of 460m²Per kg of fly ash and 5 parts of 800m specific surface area²And (3) carrying out dry mixing on/kg limestone powder for 20 minutes to obtain the coal gangue-based admixture.

Test example

The gangue-based admixture prepared in the examples 1 to 3 was mixed into cement mortar by 30 parts by mass of a cementitious material, and fluidity and activity tests were performed. In addition, pure cement mortar is used as a blank group, gangue powder mortar without silane coupling agent, fly ash and limestone powder is used as a control group, and the test results of the groups are shown in table 1:

TABLE 1 Water requirement, fluidity ratio and Activity test results for coal gangue admixtures of each example

As can be seen from table 1, by using the embodiment of the present invention, the activity of the coal gangue powder can be improved, and the influence of the coal gangue powder on the fluidity of the cement mortar is improved by the modification of the surface of the coal gangue by the silane coupling agent, the ball effect, the lubricity and the particle stacking effect of the fly ash and the limestone.

It should be noted that, in addition to the above examples, the inventor also performed other examples of changing the amount of the components (e.g., end point values and intermediate values), changing the steam curing temperature, steam curing time, calcining temperature, calcining time, etc. by experimental design methods such as orthogonal experiments, etc., so that the obtained coal gangue-based admixture has better activity and fluidity, is improved compared with the control group, has no negative influence on the workability of concrete during implementation, and can meet the requirements of various field constructions on concrete.

It should be noted that, the steam cured product is pelletized in a pelletizer, and then the pelletized mixture is calcined, which can make the phases react better and more fully at high temperature, but this is not a necessary condition, and the gangue-based admixture can also be prepared by directly calcining after steam curing.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.