Concrete and preparation method thereof
Technical Field
The invention relates to the field of concrete, in particular to concrete and a preparation method thereof.
Background
Compared with other building materials (such as steel, wood, plastics and the like), the concrete has the advantages of good water resistance, plasticity, wide raw material source, simple production process, low production cost, convenient application and the like, and is always favored by the engineering industry. The advantages of various raw materials cannot be effectively utilized in the processing process of the existing concrete, so that various materials cannot generate the complementary effect of the advantages, and the wide use and development of the concrete are limited.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide the concrete and the preparation method thereof, the preparation method is reliable and easy, the production cost is reduced, and the obtained concrete has good properties such as early strength, workability, pumpability, crack resistance and the like.
In order to achieve the purpose, the invention adopts the following technical scheme:
the concrete comprises the following components in parts by mass: 14-20% of portland cement, 6-10% of active fly ash, 3-5% of copper tailing powder, 0.2-0.4% of magnesium hydroxide, 0.4-0.8% of sodium chloride, 0.8-1.7% of modified basalt fiber, 25-30% of broken stone, 28.3-37.9% of waste ceramic tile sand, 0.5-1% of modified polycarboxylate ether water reducer and 8-10.5% of water.
The particle size of the broken stone is 10-15 mm, and the particle size of the waste ceramic tile sand is smaller than 4 mm.
A preparation method of concrete comprises the following steps:
(1) putting the fly ash into an excessive 2mol/L sodium hydroxide solution, soaking for 1.5h at 80 ℃, cooling and filtering to obtain active fly ash and a first filtrate;
the fly ash is mainly an industrial waste discharged from a flue after pulverized coal ground in a coal-fired power plant is subjected to high-temperature suspension combustion in a boiler. The fly ash is used as a mineral admixture for concrete, the mixing amount of the fly ash not only affects the strength of the concrete, but also changes the working properties of the concrete, such as bleeding property, workability and the like, but the concrete only uses untreated fly ash, so that the utilization rate is low, and the volcanic ash activity of the concrete cannot be fully exerted. In the step, the sodium hydroxide is adopted to activate and modify the fly ash, so that the surface activity and the adsorption performance of the fly ash are improved, impurities in fly ash holes can be removed, and the strength, the impermeability and the pumping performance of concrete can be further improved.
(2) Stirring and mixing basalt fibers and excessive 2mol/L diluted hydrochloric acid, soaking for 1h at room temperature, reserving a first filtrate of which the amount of the substance is twice of that of a magnesium hydroxide substance in the mixture ratio, adding the remaining first filtrate into a basalt fiber soaking system to neutralize the diluted hydrochloric acid, and filtering to obtain modified basalt fibers;
the basalt fiber is a novel inorganic environment-friendly green high-performance fiber material, is a glassy basalt ore formed by volcanic explosion, is formed by oxides such as silicon dioxide, aluminum oxide, calcium oxide, magnesium oxide, iron oxide, titanium dioxide and the like through high temperature, has the advantages of high temperature resistance, chemical corrosion resistance, natural silicate compatibility, high tensile strength, good crack resistance, low cost and the like, and can be used for improving the performance of concrete. Because the basalt fiber and the cement matrix have no chemical action, the interface bonding between the basalt fiber and the cement matrix is very weak, so that the mechanical property of the concrete is not improved ideally after the basalt fiber is added. In the step, the surface of the basalt fiber is etched by dilute hydrochloric acid, and oxide impurities on the surface of the basalt fiber are removed, so that the surface of the basalt fiber is rough, the contact area of the basalt fiber and a cement matrix is increased, the friction force between the fiber and the cement matrix is increased, and the interface bonding strength between the basalt fiber and concrete is improved. In the step, the addition amount of the basalt fibers is less, so that the excessive dilute hydrochloric acid is relatively less than that of the rest first filtrate, and the first filtrate (containing sodium hydroxide) is utilized to neutralize and remove the dilute hydrochloric acid, so that the dilute hydrochloric acid and the sodium hydroxide are used for generating sodium chloride, and the problem that the magnesium hydroxide cannot be generated subsequently due to the existence of the dilute hydrochloric acid can be avoided. In addition, the filtrate of the treated fly ash is used as a neutralizer of dilute hydrochloric acid, so that the consumption of sodium hydroxide can be reduced, and the production cost is reduced.
(3) Preparing magnesium chloride powder and water into a solution, adding active fly ash and modified basalt fiber, stirring and mixing, adding the first filtrate left in the step (2) for reaction to obtain a primary mixture, and reacting magnesium chloride with sodium hydroxide to generate magnesium hydroxide and sodium chloride in the reaction process;
the magnesium hydroxide is added into the concrete, and the mutual extrusion among magnesium hydroxide crystals can fill the pores of the concrete and form macroscopic expansion which basically does not react with other components in the concrete slurry, thereby achieving the purposes of reducing the porosity of the concrete, improving the pore structure and the compactness and also improving the impermeability and the corrosion resistance. The sodium chloride added into the concrete can play a role in resisting freezing, can also promote the setting and hardening of the concrete and improve the early strength. In the step, the mode of generating magnesium hydroxide by reacting the added magnesium chloride with sodium hydroxide is adopted, rather than directly adding magnesium hydroxide powder for mixing in the step (3), the reason is that the magnesium hydroxide powder is difficult to dissolve in water, the adding amount is small, the magnesium hydroxide powder is difficult to uniformly distribute in the mixture of the active fly ash and the modified basalt fiber, and OH in a sodium hydroxide solution-Is uniformly distributed, so that the generated magnesium hydroxide can be uniformly dispersed in the mixed system. In addition, a certain amount of water can be brought in after the filtrate is left and added, the water-cement ratio of the concrete is properly improved by the part of water, the fluidity of the concrete is improved, but the amount is still in the range of the design consideration of the proportion, and the influence on the strength of the concrete is small. In addition, magnesium hydroxide is easy to react with water and carbon dioxide in the air to generate magnesium carbonate in the long-term storage process, so that part of magnesium hydroxide is ineffective because ofThe magnesium hydroxide must be stored in a dry environment, while the magnesium chloride does not react with carbon dioxide, which is more convenient for storage.
(4) And adding the portland cement, copper tailing powder, broken stone, waste ceramic tile sand and the modified polycarboxylate ether water reducer into the primary mixture, and stirring and mixing to obtain the concrete.
The polycarboxylic acid water reducing agent has the characteristics of low mixing amount, high water reducing rate, good dispersibility, environmental protection, good adaptability and the like, is widely applied to various concretes, can reduce the fluidity of concrete cement-based materials, however, the polycarboxylic acid water reducing agent with high water reducing rate can reduce the cohesiveness of the concrete, is easy to bleed and separate, and thus influences the early strength and durability of the concrete; cellulose ether is applied to concrete, plays a role in increasing liquid phase viscosity (thickening), and can improve bleeding and segregation, so that the most common method at present is to compound a polycarboxylic acid water reducing agent and the cellulose ether to improve the performance of the concrete, but the phenomenon that viscosity disappears and precipitates can actually occur when the cellulose ether is dissolved in water and added into the polycarboxylic acid water reducing agent, so that the cellulose ether loses effectiveness, and the best improvement effect cannot be achieved. In the step, the modified polycarboxylate ether water reducer is a MELFLUX 2651F product produced by Pasteur Germany.
The invention has the beneficial effects that:
(1) the sodium hydroxide is used for activating the fly ash, so that the surface activity and the adsorption performance of the fly ash are improved, impurities in fly ash holes can be removed, and the strength, the impermeability and pumping performance of concrete can be further improved.
(2) The basalt fiber is etched by using a dilute hydrochloric acid solution, so that the surface of the basalt fiber is rough, the contact area between the basalt fiber and a concrete matrix is increased, the friction force between the fiber and the matrix is increased, and the interface bonding strength between the basalt fiber and the concrete is improved; the filtrate obtained after the fly ash is activated is utilized to neutralize the dilute hydrochloric acid, so that the consumption of sodium hydroxide is reduced, and the production cost is reduced;
(3) magnesium chloride and filtrate obtained after the activated fly ash react to generate magnesium hydroxide and sodium chloride, so that the produced magnesium hydroxide can be uniformly dispersed in a system, the porosity of concrete is reduced, the pore structure is improved, the compactness is improved, the strength of the concrete is improved, and the magnesium chloride is easier to store compared with the magnesium hydroxide and can reduce the storage cost; the generated sodium chloride can promote the setting and hardening of concrete, improve the early strength and play a role in cracking resistance.
Detailed Description
The invention is further described below with reference to specific embodiments:
example 1
The concrete comprises the following components in parts by mass: 18% of portland cement, 6% of active fly ash, 4% of copper tailing powder, 0.4% of magnesium hydroxide, 0.8% of sodium chloride, 1% of modified basalt fiber, 25% of broken stone with the particle size of 10-15 mm, 35.3% of waste ceramic tile sand with the particle size of less than 4mm, 1% of modified polycarboxylate ether water reducer and 10.5% of water.
A preparation method of concrete comprises the following steps:
(1) putting the fly ash into an excessive 2mol/L sodium hydroxide solution, soaking for 1.5h at 80 ℃, cooling and filtering to obtain active fly ash and a first filtrate;
(2) stirring and mixing basalt fibers and excessive 2mol/L diluted hydrochloric acid, soaking for 1h at room temperature, reserving a first filtrate of which the amount of the substance is twice of that of a magnesium hydroxide substance in the mixture ratio, adding the remaining first filtrate into a basalt fiber soaking system to neutralize the diluted hydrochloric acid, and filtering to obtain modified basalt fibers;
(3) preparing magnesium chloride powder and water into a solution, adding active fly ash and modified basalt fiber, stirring and mixing, adding the first filtrate left in the step (2) for reaction to obtain a primary mixture, and reacting magnesium chloride with sodium hydroxide to generate magnesium hydroxide in the reaction process;
(4) and adding the portland cement, copper tailing powder, broken stone, waste ceramic tile sand and the modified polycarboxylate ether water reducer into the primary mixture, and stirring and mixing to obtain the concrete.
Example 2
The paint comprises the following components in parts by mass: 14% of portland cement, 6% of active fly ash, 3% of copper tailings powder, 0.2% of magnesium hydroxide, 0.4% of sodium chloride, 0.8% of modified basalt fiber, 30% of broken stone with the particle size of 10-15 mm, 37.9% of waste ceramic tile sand with the particle size of less than 4mm, 0.7% of modified polycarboxylate ether water reducer and 7% of water.
A concrete was prepared according to the formulation of example 2 and the preparation method of example 1.
Example 3
The paint comprises the following components in parts by mass: 16.8% of portland cement, 8% of active fly ash, 5% of copper tailing powder, 0.3% of magnesium hydroxide, 0.6% of sodium chloride, 1.7% of modified basalt fiber, 25% of crushed stone with the particle size of 10-15 mm, 33.6% of waste ceramic tile sand with the particle size of less than 4mm, 0.5% of modified polycarboxylate ether water reducer and 8.5% of water.
A concrete was prepared according to the formulation of example 3 and the preparation method of example 1.
Example 4
The paint comprises the following components in parts by mass: 16% of portland cement, 9% of active fly ash, 3% of copper tailing powder, 0.4% of magnesium hydroxide, 0.8% of sodium chloride, 1% of modified basalt fiber, 226% of broken stone with the particle size of 10-15 mm, 34.8% of waste ceramic tile sand with the particle size of less than 4mm, 1% of modified polycarboxylate ether water reducer and 8% of water.
A concrete was prepared according to the formulation of example 4 and the preparation method of example 1.
Example 5
The paint comprises the following components in parts by mass: 20% of portland cement, 6% of active fly ash, 3% of copper tailing powder, 0.2% of magnesium hydroxide, 0.4% of sodium chloride, 1.5% of modified basalt fiber, 25% of crushed stone with the particle size of 10-15 mm, 33.4% of waste ceramic tile sand with the particle size of less than 4mm, 0.5% of modified polycarboxylate ether water reducer and 10% of water.
A concrete was prepared according to the formulation of example 5 and the preparation method of example 1.
Example 6
The paint comprises the following components in parts by mass: 17% of portland cement, 8.5% of active fly ash, 5% of copper tailings powder, 0.3% of magnesium hydroxide, 0.6% of sodium chloride, 0.8% of modified basalt fiber, 27% of broken stone with the particle size of 10-15 mm, 30.8% of waste ceramic tile sand with the particle size of less than 4mm, 1% of modified polycarboxylate ether water reducer and 9% of water.
A concrete was prepared according to the formulation of example 6 and the preparation method of example 1.
Example 7
The paint comprises the following components in parts by mass: 18.5% of portland cement, 10% of active fly ash, 4% of copper tailings powder, 0.4% of magnesium hydroxide, 0.8% of sodium chloride, 1% of modified basalt fiber, 26.5% of crushed stone with the particle size of 10-15 mm, 28.3% of waste ceramic tile sand with the particle size of less than 4mm, 1% of modified polycarboxylate ether water reducer and 9.5% of water.
A concrete was prepared according to the formulation of example 7 and the preparation method of example 1.
Comparative examples 1 to 7
The preparation method is carried out according to the mixture ratio and the preparation method of the embodiments 1-7, and the difference is that in the step (3), magnesium hydroxide powder, sodium chloride and water are prepared into turbid liquid, activated fly ash and modified basalt fiber are added, and the mixture is stirred and mixed to obtain a primary mixture.
Comparative examples 8 to 14
The preparation method is carried out according to the mixture ratio and the preparation method of the embodiments 1 to 7, and the difference is that the step (2) is omitted, and the commercially available unmodified basalt fiber is directly adopted.
Table 1 shows statistics of performance test data of the concrete of examples 1-7, comparative examples 1-7, and comparative examples 8-14. As can be seen from Table 1, the concrete obtained by directly adding magnesium hydroxide has higher compressive strength than the concrete obtained by directly adding magnesium hydroxide generated by the reaction of magnesium chloride and sodium hydroxide, and the addition of the modified basalt fiber can obviously improve the crack resistance of the concrete.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.