阅读说明：本技术 一种基于绿色地聚合物和疏浚砂的新型细粒混凝土及其制备方法 (Novel fine concrete based on green geopolymer and dredged sand and preparation method thereof ) 是由 谢凤一 邵玉琪 王兴超 李晶晶 于涛 吕德永 董朝明 王小华 殷四和 吉加强 陈 于 2020-07-14 设计创作，主要内容包括：本发明公开一种基于绿色地聚合物和疏浚砂的新型细粒混凝土：包括以下主要原料：粉煤灰、偏高岭土、水玻璃、氢氧化钠、疏浚砂、废弃陶瓷粉、聚丙烯纤维、高效减水剂和水。本发明还公开一种以疏浚砂为主要原料的细粒混凝土的制备方法,包括以下步骤：S01,向搅拌机中加入偏高岭土、粉煤灰搅拌1分钟；加入碱激发剂溶液；S02,加入疏浚砂、废弃陶瓷粉,聚丙烯纤维；然后加入聚羧酸高效减水剂和水；S03,将拌合均匀的物料分层分次加入试模；S04,成型后在试模表面覆盖薄膜,脱模后试件在标准条件下养护至规定龄期。本发明提供的一种基于绿色地聚合物和疏浚砂的新型细粒混凝土及其制备方法,能够利用废弃疏浚砂和粉煤灰等工业废渣,制备性能优良的新型细粒混凝土。(The invention discloses a novel fine concrete based on green geopolymer and dredged sand: the method comprises the following main raw materials: fly ash, metakaolin, water glass, sodium hydroxide, dredged sand, waste ceramic powder, polypropylene fiber, a high-efficiency water reducing agent and water. The invention also discloses a preparation method of the fine concrete taking the dredged sand as the main raw material, which comprises the following steps: s01, adding metakaolin and fly ash into the stirrer and stirring for 1 minute; adding an alkali activator solution; s02, adding dredged sand, waste ceramic powder and polypropylene fiber; then adding a polycarboxylic acid high-efficiency water reducing agent and water; s03, adding the uniformly mixed materials into a test mold in a layering and grading manner; and S04, covering a film on the surface of the test mold after molding, and curing the test piece to a specified age under standard conditions after demolding. The novel fine concrete based on the green geopolymer and the dredged sand and the preparation method thereof can prepare the novel fine concrete with excellent performance by utilizing industrial waste residues such as waste dredged sand, fly ash and the like.)

1. Novel fine-grained concrete based on green geopolymers and dredged sand, characterized in that: the raw materials of the novel fine concrete comprise a geopolymer cementing material, dredged sand, waste ceramic powder, polypropylene fiber, a high-efficiency water reducing agent and water.

2. Novel fine-grained concrete based on geopolymer green and dredged sand according to claim 1, characterized in that: the raw materials are as follows by mass percent; 18% -23% of geopolymer cementing material; dredging sand 64-70%; 6-8% of waste ceramic powder; 6-10% of water; 0.08-0.1% of polypropylene fiber; 0.5-1.0% of high-efficiency water reducing agent.

3. Novel fine-grained concrete based on geopolymer green and dredged sand according to claim 1, characterized in that: the geopolymer cementing material is prepared by taking fly ash and metakaolin as main raw materials under the excitation of alkali activator water glass and sodium hydroxide.

4. A new fine grained concrete based on geopolymer green and dredged sand according to claim 3, characterized in that: the fly ash is II-grade ash, and the chemical component of the fly ash is mainly SiO₂、Al₂O₃、Fe₂O₃、CaO、MgO、SO₃(ii) a The metakaolin mainly comprises SiO₂、Al₂O₃、Fe₂O₃CaO and MgO; the modulus of the water glass is 2.5-3.0, and the concentration of the sodium hydroxide solution is 3-4M.

5. The novel fine-grained concrete based on green geopolymers and dredged sand as claimed in claim 4, wherein the geopolymer cement comprises the following components in percentage by mass: 20 parts of fly ash and metakaolin, wherein the mass ratio of fly ash and kaolin is 80: and (3) the composite activator is 80:20, wherein the composite activator comprises 80 mass percent of sodium silicate and 20 mass percent of sodium hydroxide.

6. A novel fine concrete based on geopolymer green and dredged sand according to claim 1, the dredged sand having a main chemical composition comprising: SiO 2₂、Al₂O₃、Fe₂O₃、CaO、MgO、K₂O、Na₂O、TiO₂And SO₃(ii) a The fineness modulus of the dredged sand is 0.2-0.7, and the density is 1.2-1.8 g/cm³(ii) a The particle size of the particles is less than 0.3mm, and the mud content is less than 10%.

7. Novel fine-grained concrete based on geopolymer green and dredged sand according to claim 1, characterized in that: the ceramic powder is prepared by cleaning various waste ceramics, mechanically crushing the waste ceramics and grinding the waste ceramics into powder, and the apparent density of the ceramic powder is 2200 to 2500kg/m³The specific surface area is 400-500 m²Per kg, particle size less than 80 μm, and SiO as main chemical component₂、Al₂O₃、Fe₂O₃CaO, MgO and SO₃。

8. Novel fine-grained concrete based on geopolymer green and dredged sand according to claim 1, characterized in that: the fiber is chopped polypropylene fiber, the length of the polypropylene fiber is 10-24 mm, and the density of the polypropylene fiber is 2.6-2.8 g/cm³The addition of fiber improves the crack susceptibility of fine concrete and simultaneously improves the toughness and volume stability of the concrete matrix.

9. A novel fine concrete preparation method based on green geopolymers and dredged sand is characterized in that: the method comprises the following steps:

s01, adding metakaolin and fly ash into the stirrer and stirring for 1 minute; adding alkali activator solution which is prepared in proportion and comprises water glass and sodium hydroxide, stirring for 2 minutes until the mixture is uniformly mixed, and preparing geopolymer slurry;

s01, adding the dredged sand and the waste ceramic powder according to the mixing proportion, and stirring the polypropylene fibers for 1-2 minutes until the materials are uniformly mixed; and adding a polycarboxylic acid high-efficiency water reducing agent and water by a same mixing method, and wet-mixing for 2-3 min until the aggregate is uniformly dispersed.

And S03, adding the uniformly mixed materials into a test mold layer by layer, vibrating the materials added into the test mold 1/2 for 30S on a vibrating table, adding the materials while vibrating, and controlling the vibration molding time to be about 2 minutes.

And S04, covering a film on the surface of the test mold after molding, demolding after 12-24 hours, and curing the test piece to a specified age under standard conditions after demolding to obtain the fine concrete based on the geopolymer and the dredged sand.

Technical Field

The invention relates to novel fine concrete based on green geopolymer and dredged sand and a preparation method thereof, belonging to the technical field of new energy related to waste utilization.

Background

With the advancement of social sustainable development, environmental protection consciousness is gradually deepening, but energy consumption is also continuously increased, the yield of the fly ash serving as a byproduct in the energy industry is increased day by day, and the improvement of the reutilization rate of the solid waste fly ash resource is more and more emphasized. In addition, the common portland cement gel material not only consumes a great amount of non-renewable resources in production, but also discharges CO₂High in quantity and causes other dust pollution, and low in strength. The geopolymer gel material is a novel green gel material with a three-dimensional net structure formed by an alkali activator silicon-aluminum material, has various excellent performances such as quick setting early strength, high temperature resistance, good durability and the like, can be used as raw materials of solid wastes such as fly ash and slag of high-silicon high-aluminum, can improve the reutilization rate of the solid wastes such as the fly ash resource, can replace common silicate cement, and is a low-cost, high-performance and environment-friendly material.

On the other hand, in order to maintain normal navigation of a Yangtze river deepwater channel and the like, a large amount of dredging sand is generated by channel dredging every year, at present, the dredging sand is mostly treated in an external throwing mode, the cost required by external throwing is high, a large amount of carbon emission is generated, and the environmental pollution is serious. Furthermore, laws and regulations for forbidding river sand excavation are issued in the country, and along with the emphasis of the country on environmental protection, modes of mountain mining, stone mining and the like are limited, so that stones and sand for concrete face serious shortage and exhaustion. Therefore, the dredged sand is reasonably utilized to prepare novel fine concrete with early setting, early strength and good durability, and the novel fine concrete can replace common concrete to prepare ballast blocks, facing bricks and the like to be applied to projects such as navigation channel renovation projects and the like nearby. The method can reduce environmental pollution, fully utilize dredging, effectively relieve the problems of shortage and exhaustion of natural sandstone materials, find an effective way for resource utilization of waste dredged sand, greatly utilize industrial waste residues such as fly ash and the like, reduce the using amount of cement, reduce the construction cost, accord with the national concept of 'exploring a new way of ecological priority and green development in the Yangtze river economic zone', and have important significance for promoting ecological water conservancy construction.

Disclosure of Invention

The invention aims to provide a green-based materialThe novel fine concrete of chromoplast polymer and dredged sand and its preparation method solve the problems of traditional concrete using ordinary portland cement and river sand, not only consuming a lot of non-renewable resources, discharging CO₂The amount is large and other dust pollution is caused, and the novel fine concrete with excellent performance is prepared by fully utilizing industrial waste residues such as waste dredged sand, fly ash and the like to replace common concrete.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a novel fine concrete based on green geopolymer and dredged sand comprises the following components in percentage by mass; 18% -23% of geopolymer; dredging sand 64-70%; 6-8% of waste ceramic powder; 6-10% of water; 0.08-0.1% of polypropylene fiber; 0.5-1.0% of high-efficiency water reducing agent (the percentage of the total amount of the cementing material), wherein the geopolymer is prepared by taking fly ash and metakaolin as raw materials and water glass and sodium hydroxide as alkali activators.

The geopolymer is a self-made non-calcined alkali-activated green geopolymer cementing material, and is a green environment-friendly three-dimensional network cementing body which is generated by taking industrial solid waste fly ash as a main raw material under the excitation of alkali activator water glass, sodium hydroxide and the like. The fly ash is II-grade ash, and the chemical component of the fly ash is mainly SiO₂、Al₂O₃、Fe₂O₃、CaO、MgO、SO₃(ii) a The metakaolin mainly comprises SiO₂、Al₂O₃、Fe₂O₃CaO and MgO; the modulus of the water glass is 2.5-3.0, and the concentration of the sodium hydroxide solution is about 3-4M.

The dredged sand comprises the following main chemical components: SiO 2₂、Al₂O₃、Fe₂O₃、CaO、 MgO、K₂O、Na₂O、TiO₂And SO₃(ii) a The fineness modulus of the dredged sand is 0.3-0.7, and the density is 1.2-1.8 g/cm³(ii) a The particle size of the particles is less than 0.3mm, and the mud content is less than 10%.

The ceramic powder is prepared by cleaning various waste ceramics, mechanically crushing, and grinding into powder with dense appearanceThe degree of the reaction is 2200 to 2500kg/m^3，The specific surface area is 400-500 m²/kg, the particle size is less than 80 μm. The main chemical component of the material is SiO₂、Al₂O₃、Fe₂O₃CaO, MgO and SO₃. Aims to lead the prepared concrete to form compact and stacked particles through good and reasonable particle grading by the filling effect of waste ceramic fine particles and improve the working performance, the mechanical property and the like of the dredged sand fine particle concrete.

The high-efficiency water reducing agent is a polycarboxylic acid high-efficiency water reducing agent, the water-gel ratio is reduced by adding the water reducing agent, and the fluidity is improved.

The fiber is chopped polypropylene fiber, the length of the polypropylene fiber is 10-24 mm, and the density of the polypropylene fiber is 2.6-2.8 g/cm³The addition of the fiber improves the easy cracking property of the fine concrete and simultaneously improves the toughness and the volume stability of the concrete matrix;

a novel fine concrete preparation method based on green geopolymers and dredged sand comprises the following steps:

(1) adding metakaolin and fly ash into the stirrer, and stirring for 1 minute; adding alkali activator solution which is prepared in proportion and comprises water glass and sodium hydroxide, stirring for 2 minutes until the mixture is uniformly mixed, and preparing geopolymer slurry;

(2) then adding the dredged sand, the waste ceramic powder and the polypropylene fiber according to the mixture ratio, and stirring for 1-2 minutes until the materials are uniformly mixed; and adding a polycarboxylic acid high-efficiency water reducing agent and water by a same mixing method, and wet-mixing for 2-3 min until the aggregate is uniformly dispersed.

(3) And adding the uniformly mixed materials into the test mold layer by layer, vibrating the materials added into the test mold 1/2 on a vibrating table for 30s, adding the materials while vibrating, and controlling the vibration forming time to be about 2 minutes.

(4) And covering a film on the surface of the test mold after molding, demolding after 12-24 hours, and maintaining the test piece to a specified age under standard conditions after demolding to obtain the novel fine concrete based on the geopolymer and the dredged sand.

Compared with the prior art, the invention has the following beneficial effects:

1. the fine concrete has the same main composition and components as common concrete, consists of cement, coarse aggregate, fine aggregate, water and additives, and can be used for replacing common concrete, wherein dredged sand replaces the coarse aggregate in the common concrete, waste ceramic powder is used as a filler for replacing the fine aggregate in the common concrete, green polymer replaces the common portland cement to be a cementing material, and meanwhile, a high-efficiency water reducing agent must be added to reduce the water consumption. The concrete with the composition is prepared into novel concrete taking dredging sand as a main raw material by the filling effect of waste ceramic powder filler fine particles based on the obtained reasonable and good particle gradation and the physical and chemical dual effects of hydration of geopolymer gelled materials. The fine concrete has superior performance due to the dual effects of physical close gradation and cement hydration chemistry. In addition, fine concrete does not use stones as compared with ordinary concrete, and has a lower cement amount and higher strength as compared with ordinary mortar.

2. The alkali-activated geopolymer is used as a gel material to replace common portland cement, and the geopolymer material is a green environment-friendly three-dimensional network gel body with excellent performance and prepared by taking industrial solid waste coal ash rich in aluminosilicate minerals and the like as main raw materials under the condition of a chemical activator. The cementing material is formed by alkali excitation, does not need high-temperature calcination, can greatly utilize industrial waste residues such as fly ash and the like, conforms to the ecological concept, and has the characteristics of quick setting and hardening, high early strength, excellent acid-base corrosion resistance and durability, high temperature resistance and the like.

3. The fine concrete of the invention does not use stones, can use a large amount of dredging sand, not only solves the problem of environmental pollution caused by dredging wastes, but also solves the problems of serious shortage and exhaustion of the existing natural sandstone materials, reduces the construction cost and achieves multiple purposes.

4. The invention optimizes the mixing ratio of various raw materials, prepares fine concrete with excellent performances in various aspects such as quick setting early strength, environmental protection, good durability and the like, and overcomes the technical problems of high energy consumption, serious environmental pollution and low strength of the existing concrete.

Detailed Description

The present invention will be further described below.

Examples are according to preparation 1m³The concrete material is prepared by the following steps of obtaining the concrete according to the mass ratio of the raw materials, wherein the mass value ranges of the concrete are as follows: 378-483 kg of geopolymer, 1344-1470 kg of dredging sand, 126-168 kg of waste ceramic powder, 126-210 kg of water, 1.68-2.1 kg of polypropylene fiber and 1.05-2.73 kg of high-efficiency water reducing agent.