CN116081971A - Method for preparing fine recycled aggregate from waste concrete - Google Patents

Abstract

The invention discloses a method for preparing fine recycled aggregate from waste concrete, which belongs to the technical field of recycled aggregate and comprises the following steps: crushing the waste concrete into particles with the diameter smaller than 20mm by using a jaw crusher, and then removing waste iron contained in the original waste concrete by using a magnetic separator through the crushed waste particles; calcining the waste concrete particles at 700-800 ℃, cooling the calcined and cooled waste concrete particles, transferring the waste concrete particles into a reaction kettle, and introducing water vapor under the stirring condition to heat and humidify; grinding the particles treated in the step S2 by a ball mill, and sieving by a vibrating screen to remove particles with the particle size of more than 75 mu m; placing the screened particles into a reaction kettle, adding diatomite, introducing carbon dioxide gas, and stirring and mixing at a high speed; and adding the mixture into the aggregate strengthening liquid, soaking for 25-40h, and then drying and grinding to obtain the fine recycled aggregate. The porosity of the recycled aggregate is reduced, the water absorption of the aggregate is effectively reduced, and the performance of the recycled aggregate is effectively improved.

Description

Method for preparing high-quality recycled aggregate from waste concrete

technical field

The invention relates to the technical field of recycled aggregates, in particular to a method for preparing high-quality recycled aggregates from waste concrete.

Background technique

With the steady advancement of urbanization in our country, many urban and rural buildings have been demolished, resulting in a large amount of construction waste, which has caused a bad impact on China's environmental protection. At the same time, a large amount of natural sand and gravel have been consumed in the process of urbanization. Sand and gravel aggregate resources are increasingly scarce, and waste concrete blocks have been buried or directly discarded as a kind of solid waste. The technical problem of making building aggregates from waste concrete has always been one of the difficult problems. The waste concrete is crushed and screened to produce Recycled aggregates that can partially or completely replace natural sandstone aggregates. Compared with natural sandstone aggregates, recycled aggregates have higher porosity and water absorption than natural sandstone aggregates, which affects the practical application of recycled aggregates. Therefore, we propose a method of preparing high-quality recycled aggregates from waste concrete to solve the above problems.

Contents of the invention

The purpose of the present invention is to provide a method for preparing high-quality recycled aggregate from waste concrete, so as to solve the problems raised in the above-mentioned background technology.

In order to achieve the above object, the present invention provides the following technical scheme: the method for preparing high-quality recycled aggregate from waste concrete comprises the following steps:

S1. Use a jaw crusher to crush the waste concrete into particles with a diameter of less than 20 mm, and then pass the crushed waste particles through a magnetic separator to remove the scrap iron contained in the original waste concrete;

S2. Under the condition of 700-800°C, calcining the waste concrete particles, after calcining and cooling, move them into the reaction kettle, and under the condition of stirring, pass in water vapor to heat and humidify;

S3. Grinding the particles treated in step S2 with a ball mill, and then sieving through a vibrating sieve to remove particles with a particle size greater than 75 μm;

S4. Put the screened particles into the reaction kettle, add diatomaceous earth, feed carbon dioxide gas, and stir and mix at a high speed;

S5. Add the mixed material into the aggregate strengthening liquid and soak for 25-40 hours, then dry and grind to obtain the high-quality recycled aggregate.

In a preferred embodiment, in step S2, the calcination time is 1-2h, steam is introduced until the temperature reaches 180-200°C, the pressure in the reactor is maintained at 1.3-1.5MPa, and the stirring speed is 800-1000r/min.

A preferred implementation example, in step S4, the quality of the diatomite is 3%-8% of the concrete particles, the internal pressure of the reactor is 1.2-1.3MPa, and the carbon dioxide feeding time and stirring time are 0.5-1h.

In a preferred embodiment, the aggregate strengthening liquid is calculated in parts by weight, and its raw material composition includes: 30-40 parts of silica fume, 25-35 parts of alumina powder, 60-80 parts of lye, 15-30 parts of sodium carbonate 20-40 parts of inorganic filler, 10-20 parts of silicone resin, 5-10 parts of penetrating agent, 2-8 parts of dispersant, 3-8 parts of water reducing agent and 80-100 parts of water.

In a preferred embodiment, the aggregate strengthening liquid is calculated in parts by weight, and its raw material composition includes: 32 parts of silica fume, 26 parts of alumina powder, 64 parts of lye, 17 parts of sodium carbonate, 24 parts of inorganic filler, silicon 12 parts of resin, 6 parts of penetrating agent, 3 parts of dispersant, 4 parts of water reducing agent and 85 parts of water.

In a preferred embodiment, the aggregate strengthening liquid is calculated in parts by weight, and its raw material composition includes: 35 parts of silica fume, 28 parts of alumina powder, 70 parts of lye, 20 parts of sodium carbonate, 28 parts of inorganic filler, silicon 14 parts of resin, 7 parts of penetrating agent, 5 parts of dispersant, 5 parts of water reducing agent and 90 parts of water.

In a preferred embodiment, the aggregate strengthening liquid is calculated in parts by weight, and its raw material composition includes: 37 parts of silica fume, 30 parts of alumina powder, 74 parts of lye, 24 parts of sodium carbonate, 34 parts of inorganic filler, silicon 16 parts of resin, 8 parts of penetrating agent, 6 parts of dispersant, 6 parts of water reducing agent and 95 parts of water.

In a preferred embodiment, the aggregate strengthening liquid is calculated in parts by weight, and its raw material composition includes: 39 parts of silica fume, 32 parts of alumina powder, 78 parts of lye, 28 parts of sodium carbonate, 38 parts of inorganic filler, silicon 18 parts of resin, 9 parts of penetrating agent, 7 parts of dispersant, 7 parts of water reducing agent and 100 parts of water.

A preferred implementation case, the lye is a mixed solution of potassium hydroxide and water glass, and the modulus of the water glass is adjusted to 1.0-1.2 by potassium hydroxide; the inorganic filler is calcium sulfoaluminate, aluminum oxide Material, calcium chloride, magnesium sulfate and potassium dihydrogen phosphate by mass ratio (1-4): (3-5): (2-6): (3-7): (2-3) mixture, the described The penetrating agent is one or more of isobutyl triethoxysilane, sodium alkylbenzene sulfonate, sodium alkyl sulfate, fatty alcohol polyoxyethylene ether and alkylphenol polyoxyethylene ether; the dispersant It is one or more of magnesium stearate, zinc stearate and HPMA; the water reducer is a polycarboxylate high-efficiency water reducer.

In a preferred embodiment, in step S5, the soaking temperature is 25-30°C, the drying temperature is 50-60°C, and the drying time is 10-12h.

The beneficial effect of the present invention is that waste concrete is fully crushed by crushing, calcining and ball milling after steam heating, and then by adding diatomaceous earth and soaking treatment with strengthening liquid, through the lye in the strengthening liquid and the waste concrete particles The alkali-silicic acid reaction occurs, so that the alkali silica gel is filled into the pores of the attached mortar, reducing the porosity of the recycled aggregate, and making the recycled aggregate increase from the apparent density of ordinary recycled aggregate of 1.98g/cm ³ to 2.3-2.4g/cm ³ , and through lye, silicone resin and various additives, the water absorption rate of the aggregate is effectively reduced, so that the water absorption rate of the ordinary recycled aggregate drops from 6.9%-7.5% to 4.5%- 5.2%, effectively improving the performance of recycled aggregate, making it close to the nature of natural aggregate, meeting the requirements of use, increasing the performance of recycled aggregate prepared from waste concrete, and saving resources and economic costs.

Description of drawings

Fig. 1 is a schematic diagram of a method for preparing high-quality recycled aggregate from waste concrete provided by an embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Embodiment 1: As shown in Figure 1, the present invention provides the method for waste concrete preparation high-quality recycled aggregate, comprising the following steps:

S1. Use a jaw crusher to crush the waste concrete into particles with a diameter of less than 20 mm, and then pass the crushed waste particles through a magnetic separator to remove the scrap iron contained in the original waste concrete;

S2. Under the condition of 700-800°C, calcining the waste concrete particles, after calcining and cooling, move them into the reaction kettle, and under the condition of stirring, pass in water vapor to heat and humidify;

S3. Grinding the particles treated in step S2 with a ball mill, and then sieving through a vibrating sieve to remove particles with a particle size greater than 75 μm;

S4. Put the screened particles into the reaction kettle, add diatomaceous earth, feed carbon dioxide gas, and stir and mix at a high speed;

S5. Add the mixed material into the aggregate strengthening liquid and soak for 25-40 hours, then dry and grind to obtain the high-quality recycled aggregate.

Further, in step S2, the calcination time is 1-2h, steam is introduced until the temperature reaches 180-200°C, the pressure in the reactor is maintained at 1.3-1.5MPa, and the stirring speed is 800-1000r/min.

Further, in step S4, the mass of the diatomite is 3%-8% of the concrete particles, the pressure inside the reactor is 1.2-1.3MPa, and the carbon dioxide feeding time and stirring time are 0.5-1h.

Further, the aggregate strengthening liquid is calculated in parts by weight, and its raw material composition includes: 32 parts of silica fume, 26 parts of alumina powder, 64 parts of lye, 17 parts of sodium carbonate, 24 parts of inorganic filler, 12 parts of silicone resin, 6 parts of penetrating agent, 3 parts of dispersant, 4 parts of water reducing agent and 85 parts of water.

Further, the lye is a mixed solution of potassium hydroxide and water glass, and the modulus of the water glass is adjusted to 1.0-1.2 by potassium hydroxide; the inorganic filler is calcium sulfoaluminate, alumina clinker, chlorinated A mixture of calcium, magnesium sulfate and potassium dihydrogen phosphate in a mass ratio of 1:3:3:3:2, the penetrating agent is isobutyltriethoxysilane; the dispersing agent is magnesium stearate and stearic acid A mixture of zinc in a mass ratio of 1:1; the water reducer is a polycarboxylate high-efficiency water reducer.

Further, in step S5, the soaking temperature is 25-30° C., the drying temperature is 50-60° C., and the drying time is 10-12 hours.

Embodiment 2: As shown in Figure 1, the present invention provides the method for preparing high-quality recycled aggregate from waste concrete, comprising the following steps:

S1. Use a jaw crusher to crush the waste concrete into particles with a diameter of less than 20 mm, and then pass the crushed waste particles through a magnetic separator to remove the scrap iron contained in the original waste concrete;

S2. Under the condition of 700-800°C, calcining the waste concrete particles, after calcining and cooling, move them into the reaction kettle, and under the condition of stirring, pass in water vapor to heat and humidify;

S3. Grinding the particles treated in step S2 with a ball mill, and then sieving through a vibrating sieve to remove particles with a particle size greater than 75 μm;

S4. Put the screened particles into the reaction kettle, add diatomaceous earth, feed carbon dioxide gas, and stir and mix at a high speed;

S5. Add the mixed material into the aggregate strengthening liquid and soak for 25-40 hours, then dry and grind to obtain the high-quality recycled aggregate.

Further, in step S2, the calcination time is 1-2h, steam is introduced until the temperature reaches 180-200°C, the pressure in the reactor is maintained at 1.3-1.5MPa, and the stirring speed is 800-1000r/min.

Further, in step S4, the mass of the diatomite is 3%-8% of the concrete particles, the pressure inside the reactor is 1.2-1.3MPa, and the carbon dioxide feeding time and stirring time are 0.5-1h.

Further, the aggregate strengthening liquid is calculated in parts by weight, and its raw material composition includes: 35 parts of silica fume, 28 parts of alumina powder, 70 parts of lye, 20 parts of sodium carbonate, 28 parts of inorganic filler, 14 parts of silicone resin, 7 parts of penetrating agent, 5 parts of dispersant, 5 parts of water reducing agent and 90 parts of water.

Further, the lye is a mixed solution of potassium hydroxide and water glass, and the modulus of the water glass is adjusted to 1.0-1.2 by potassium hydroxide; the inorganic filler is calcium sulfoaluminate, alumina clinker, chlorinated A mixture of calcium, magnesium sulfate and potassium dihydrogen phosphate in a mass ratio of 2:3:4:3:3, the penetrating agent is isobutyltriethoxysilane; the dispersing agent is magnesium stearate and stearic acid A mixture of zinc in a mass ratio of 1:2; the water reducer is a polycarboxylate high-efficiency water reducer.

Further, in step S5, the soaking temperature is 25-30° C., the drying temperature is 50-60° C., and the drying time is 10-12 hours.

Embodiment 3: As shown in Figure 1, the present invention provides the method for waste concrete preparation high-quality recycled aggregate, comprising the following steps:

S1. Use a jaw crusher to crush the waste concrete into particles with a diameter of less than 20 mm, and then pass the crushed waste particles through a magnetic separator to remove the scrap iron contained in the original waste concrete;

S2. Under the condition of 700-800°C, calcining the waste concrete particles, after calcining and cooling, move them into the reaction kettle, and under the condition of stirring, pass in water vapor to heat and humidify;

S3. Grinding the particles treated in step S2 with a ball mill, and then sieving through a vibrating sieve to remove particles with a particle size greater than 75 μm;

S4. Put the screened particles into the reaction kettle, add diatomaceous earth, feed carbon dioxide gas, and stir and mix at a high speed;

S5. Add the mixed material into the aggregate strengthening liquid and soak for 25-40 hours, then dry and grind to obtain the high-quality recycled aggregate.

Further, in step S2, the calcination time is 1-2h, steam is introduced until the temperature reaches 180-200°C, the pressure in the reactor is maintained at 1.3-1.5MPa, and the stirring speed is 800-1000r/min.

Further, in step S4, the mass of the diatomite is 3%-8% of the concrete particles, the pressure inside the reactor is 1.2-1.3MPa, and the carbon dioxide feeding time and stirring time are 0.5-1h.

Further, the aggregate strengthening liquid is calculated in parts by weight, and its raw material composition includes: 37 parts of silica fume, 30 parts of alumina powder, 74 parts of lye, 24 parts of sodium carbonate, 34 parts of inorganic filler, 16 parts of silicone resin, 8 parts of penetrating agent, 6 parts of dispersant, 6 parts of water reducing agent and 95 parts of water.

Further, the lye is a mixed solution of potassium hydroxide and water glass, and the modulus of the water glass is adjusted to 1.0-1.2 by potassium hydroxide; the inorganic filler is calcium sulfoaluminate, alumina clinker, chlorinated A mixture of calcium, magnesium sulfate and potassium dihydrogen phosphate in a mass ratio of 3:4:2:5:2, and the penetrant is a mixture of isobutyltriethoxysilane and sodium alkylbenzenesulfonate in a mass ratio of 2:3 mixture; the dispersant is HPMA; the water reducer is polycarboxylate high-efficiency water reducer.

Further, in step S5, the soaking temperature is 25-30° C., the drying temperature is 50-60° C., and the drying time is 10-12 hours.

Embodiment 4: As shown in Figure 1, the present invention provides the method for preparing high-quality recycled aggregate from waste concrete, comprising the following steps:

S1. Use a jaw crusher to crush the waste concrete into particles with a diameter of less than 20 mm, and then pass the crushed waste particles through a magnetic separator to remove the scrap iron contained in the original waste concrete;

S2. Under the condition of 700-800°C, calcining the waste concrete particles, after calcining and cooling, move them into the reaction kettle, and under the condition of stirring, pass in water vapor to heat and humidify;

S3. Grinding the particles treated in step S2 with a ball mill, and then sieving through a vibrating sieve to remove particles with a particle size greater than 75 μm;

S4. Put the screened particles into the reaction kettle, add diatomaceous earth, feed carbon dioxide gas, and stir and mix at a high speed;

S5. Add the mixed material into the aggregate strengthening liquid and soak for 25-40 hours, then dry and grind to obtain the high-quality recycled aggregate.

Further, in step S2, the calcination time is 1-2h, steam is introduced until the temperature reaches 180-200°C, the pressure in the reactor is maintained at 1.3-1.5MPa, and the stirring speed is 800-1000r/min.

Further, in step S4, the mass of the diatomite is 3%-8% of the concrete particles, the pressure inside the reactor is 1.2-1.3MPa, and the carbon dioxide feeding time and stirring time are 0.5-1h.

Further, the aggregate strengthening liquid is calculated in parts by weight, and its raw material composition includes: 39 parts of silica fume, 32 parts of alumina powder, 78 parts of lye, 28 parts of sodium carbonate, 38 parts of inorganic filler, 18 parts of silicone resin, 9 parts of penetrating agent, 7 parts of dispersant, 7 parts of water reducing agent and 100 parts of water.

Further, the lye is a mixed solution of potassium hydroxide and water glass, and the modulus of the water glass is adjusted to 1.0-1.2 by potassium hydroxide; the inorganic filler is calcium sulfoaluminate, alumina clinker, chlorinated A mixture of calcium, magnesium sulfate and potassium dihydrogen phosphate in a mass ratio of 4:5:3:5:3, the penetrating agent is sodium alkyl sulfate; the dispersant is HPMA; the water reducing agent is polycarboxylate Acid superplasticizer.

Further, in step S5, the soaking temperature is 25-30° C., the drying temperature is 50-60° C., and the drying time is 10-12 hours.

The waste concrete is crushed, calcined, steam-heated and ball-milled to make it fully broken, and then treated by adding diatomaceous earth and soaking in the strengthening solution, and the alkaline solution in the strengthening solution reacts with the waste concrete particles through alkali-silicic acid reaction. The alkali silicic acid gel is filled into the pores of the attached mortar, the porosity of the recycled aggregate is reduced, and the apparent density of the recycled aggregate is increased from 1.98g/ ^cm3 to 2.3-2.4g/cm3 ³ , and through lye, silicone resin and various additives, the water absorption rate of the aggregate can be effectively reduced, so that the water absorption rate of ordinary recycled aggregate can be reduced from 6.9%-7.5% to 4.5%-5.2%, which can effectively improve the regeneration rate of bone The performance of the material makes it close to the nature of natural aggregates, meets the requirements of use, increases the performance of recycled aggregates prepared from waste concrete, and saves resources and economic costs.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (10)

1. the method for waste concrete preparation high-quality recycled aggregate, is characterized in that, comprises the steps: S1. Use a jaw crusher to crush the waste concrete into particles with a diameter of less than 20 mm, and then pass the crushed waste particles through a magnetic separator to remove the scrap iron contained in the original waste concrete; S2. Under the condition of 700-800°C, calcining the waste concrete particles, after calcining and cooling, move them into the reaction kettle, and under the condition of stirring, pass in water vapor to heat and humidify; S3. Grinding the particles treated in step S2 with a ball mill, and then sieving through a vibrating sieve to remove particles with a particle size greater than 75 μm; S4. Put the screened particles into the reaction kettle, add diatomaceous earth, feed carbon dioxide gas, and stir and mix at a high speed; S5. Add the mixed material into the aggregate strengthening liquid and soak for 25-40 hours, then dry and grind to obtain the high-quality recycled aggregate. 2. The method for preparing high-quality recycled aggregate from waste concrete as claimed in claim 1, characterized in that: in step S2, the calcination time is 1-2h, and water vapor is introduced until the temperature reaches 180-200°C, and the pressure in the reactor remains 1.3-1.5MPa, the stirring speed is 800-1000r/min. 3. The method for preparing high-quality recycled aggregate from waste concrete as claimed in claim 1, characterized in that: in step S4, the quality of the diatomaceous earth is 3%-8% of the concrete particles, and the pressure in the reactor is is 1.2-1.3MPa, and the carbon dioxide feeding time and stirring time are 0.5-1h. 4. The method for preparing high-quality recycled aggregate from waste concrete as claimed in claim 1, characterized in that: the aggregate strengthening liquid is in parts by weight, and its raw material composition comprises: 30-40 parts of silica fume, 25 parts of alumina powder -35 parts, 60-80 parts of lye, 15-30 parts of sodium carbonate, 20-40 parts of inorganic filler, 10-20 parts of silicone resin, 5-10 parts of penetrating agent, 2-8 parts of dispersant, 3 parts of water reducer -8 parts and 80-100 parts of water. 5. The method for preparing high-quality regenerated aggregates from waste concrete as claimed in claim 4, characterized in that: the aggregate strengthening liquid is in parts by weight, and its raw material composition comprises: 32 parts of silica fume, 26 parts of alumina powder, 64 parts of lye, 17 parts of sodium carbonate, 24 parts of inorganic filler, 12 parts of silicone resin, 6 parts of penetrating agent, 3 parts of dispersing agent, 4 parts of water reducing agent and 85 parts of water. 6. The method for preparing high-quality regenerated aggregates from waste concrete as claimed in claim 4, characterized in that: the aggregate strengthening liquid is in parts by weight, and its raw material composition comprises: 35 parts of silica fume, 28 parts of alumina powder, 70 parts of lye, 20 parts of sodium carbonate, 28 parts of inorganic filler, 14 parts of silicone resin, 7 parts of penetrating agent, 5 parts of dispersing agent, 5 parts of water reducing agent and 90 parts of water. 7. The method for preparing high-quality regenerated aggregates from waste concrete as claimed in claim 4, characterized in that: the aggregate strengthening liquid is in parts by weight, and its raw material composition comprises: 37 parts of silica fume, 30 parts of alumina powder, 74 parts of lye, 24 parts of sodium carbonate, 34 parts of inorganic filler, 16 parts of silicone resin, 8 parts of penetrating agent, 6 parts of dispersant, 6 parts of water reducing agent and 95 parts of water. 8. The method for preparing high-quality regenerated aggregates from waste concrete as claimed in claim 4, characterized in that: the aggregate strengthening liquid is in parts by weight, and its raw material composition comprises: 39 parts of silica fume, 32 parts of alumina powder, 78 parts of lye, 28 parts of sodium carbonate, 38 parts of inorganic filler, 18 parts of silicone resin, 9 parts of penetrating agent, 7 parts of dispersant, 7 parts of water reducing agent and 100 parts of water. 9. The method for preparing high-quality recycled aggregate from waste concrete as claimed in claim 4, characterized in that: the lye is a mixed solution of potassium hydroxide and water glass, and the modulus of the water glass is adjusted to 1.0 by potassium hydroxide -1.2; the inorganic filler is calcium sulfoaluminate, alumina clinker, calcium chloride, magnesium sulfate and potassium dihydrogen phosphate in mass ratio (1-4): (3-5): (2-6): (3-7): The mixture of (2-3), the penetrant is isobutyltriethoxysilane, sodium alkylbenzenesulfonate, sodium alkylsulfate, fatty alcohol polyoxyethylene ether and alkylphenol One or more of polyoxyethylene ethers; the dispersant is one or more of magnesium stearate, zinc stearate and HPMA; and the water reducer is a polycarboxylate high-efficiency water reducer. 10. The method for preparing high-quality recycled aggregate from waste concrete as claimed in claim 1, characterized in that: in step S5, the soaking temperature is 25-30°C, the drying temperature is 50-60°C, and the drying time is 10-30°C. 12h.

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