Regenerated aggregate strengthening method and strengthening device

Abstract

The invention provides a method and a device for reinforcing recycled aggregate, and belongs to the technical field of regeneration of construction waste. The reinforcing method of the regenerated aggregate provided by the invention comprises the following steps: mixing the regenerated aggregate with thin slurry, and carrying out dipping and wrapping to obtain the reinforced regenerated aggregate, the dipping and wrapping are carried out under the conditions of vacuumizing and stirring. According to the method, vacuumizing and stirring are adopted while the thin slurry is infiltrated, part of air in pores in the regenerated aggregate can be pumped out through vacuumizing, and the degree of air pumped out of the pores in the regenerated aggregate can be increased through stirring, so that the thin slurry is infiltrated into the regenerated aggregate to the maximum extent, and the strengthening effect is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of construction waste recycling, and in particular relates to a method and a device for reinforcing recycled aggregate. Background Art

[0002] Processing waste concrete into recycled aggregate for the preparation of recycled concrete not only solves the problem of environmental pollution, but also realizes resource reuse and reduces the waste of resources and energy. However, compared with natural aggregates, recycled aggregates have a large number of fine cracks, high crushing index values, and high water absorption. The working performance, mechanical properties and durability of recycled cement products prepared from them are also difficult to meet engineering requirements. Therefore, strengthening recycled aggregates to improve the performance of recycled mortar is of great significance to the recycling and sustainable development of concrete.

[0003] To improve the performance defects of recycled aggregates, the current methods mainly include the coating slurry method, which is essentially to immerse the recycled aggregates of construction waste into a dilute slurry prepared by cement and mineral admixtures. It has good controllability, but due to the existence of osmotic pressure, the slurry immersed in the recycled aggregate is limited, so the improvement effect of the coating slurry method needs to be further improved. Therefore, how to further improve the strengthening effect of recycled aggregates has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0004] The object of the present invention is to provide a method and device for strengthening recycled aggregate. The strengthening method provided by the present invention has excellent strengthening effect.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for strengthening recycled aggregate, comprising:

[0007] The recycled aggregate is mixed with the slurry, and then impregnated and coated to obtain the reinforced recycled aggregate;

[0008] The impregnation and coating is carried out under vacuum and stirring conditions.

[0009] Preferably, the recycled aggregate includes recycled concrete aggregate and / or recycled aggregate containing red brick construction waste.

[0010] Preferably, the components of the slurry include cement, accelerator, fly ash, retarder and water.

[0011] Preferably, the mass of the coagulant is 30-40% of the total mass of the cement and the coagulant.

[0012] Preferably, the mass of the retarder is 1-5% of the total mass of the cement and the accelerator.

[0013] Preferably, the vacuum degree of the vacuum extraction is 3.4-4.0 KPa.

[0014] Preferably, the stirring speed is 5 to 15 rpm.

[0015] Preferably, the dipping and coating time is 30 to 90 minutes.

[0016] Preferably, the dipping and coating time is 60 minutes.

[0017] The present invention also provides a reinforcing device for recycled aggregate, comprising a negative pressure container and a stirring device arranged in the negative pressure container.

[0018] The present invention provides a method for strengthening recycled aggregate, comprising: mixing the recycled aggregate with a slurry, and performing impregnation and coating to obtain strengthened recycled aggregate; the impregnation and coating are performed under conditions of vacuuming and stirring. The present invention improves the coating slurry method, and adopts vacuuming and stirring while the slurry is infiltrating. The vacuuming can extract part of the air in the internal pores of the recycled aggregate, and the stirring can increase the degree of air extraction from the internal pores of the recycled aggregate, so that the slurry can penetrate into the interior of the recycled aggregate to the greatest extent, thereby improving the strengthening effect. Experimental results show that the apparent density of the recycled aggregate of concrete strengthened by the strengthening method provided by the present invention is 2653-2661 kg / m 3 The crushing value is 15.84-15.92%, the water absorption rate is 3.89-3.98%; the apparent density of the recycled aggregate of construction waste containing 25% red bricks (volume replacement method) is 2432kg / m 3 The crushing value is 24.86%, the water absorption rate is 8.53%; the apparent density of the recycled aggregate of construction waste containing 50% red bricks (volume replacement method) is 2156kg / m 3 , the crushing value is 26.86% and the water absorption rate is 11.74%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The reinforcing device for recycled aggregate provided by the present invention, in the figure, 1 is a verification interface, 2 is a pressure regulating device, 3 is a vacuum gauge, 4 is a vacuum pump, 5 is a drying or water accumulation device, 6 is a negative pressure container, 7 is a pressure gauge, and 8 is a stirring device. DETAILED DESCRIPTION

[0020] The present invention provides a method for strengthening recycled aggregate, comprising:

[0021] The recycled aggregate is mixed with the slurry, and then impregnated and coated to obtain the reinforced recycled aggregate;

[0022] The impregnation and coating is carried out under vacuum and stirring conditions.

[0023] The present invention has no particular limitation on the sources of the raw materials, and commercially available products known to those skilled in the art may be used.

[0024] The strengthening method provided by the present invention is applicable to recycled aggregates, preferably to recycled aggregates of concrete and / or recycled aggregates containing red brick construction waste.

[0025] The invention mixes the recycled aggregate with the slurry, performs impregnation and coating, and obtains the reinforced recycled aggregate.

[0026] In the present invention, the recycled aggregate preferably includes recycled concrete aggregate and / or recycled aggregate containing red brick construction waste; the particle size of the recycled aggregate is preferably 10 to 30 mm.

[0027] In the present invention, when the particle size of the recycled aggregate does not meet the requirement of 10 to 30 mm, the recycled aggregate is preferably crushed. The present invention has no special limitation on the crushing operation, and the operation well known to those skilled in the art can be used to make the particle size of the recycled aggregate meet the requirement.

[0028] As an implementation mode, the particle size of the recycled aggregate may be 10 to 20 mm, or 20 to 30 mm.

[0029] In the present invention, the components of the slurry preferably include cement, accelerator, fly ash, retarder and water.

[0030] In the present invention, the mass of the cement is preferably 70-90% of the total mass of the cement and the accelerator.

[0031] In the present invention, the coagulant is preferably a liquid coagulant; the liquid coagulant is preferably sodium aluminate; the mass of the coagulant is preferably 10-30% of the total mass of cement and the coagulant. In the present invention, the coagulant can improve the strength and shrinkage resistance of the slurry; limiting the mass of the coagulant within the above range can improve the strength and shrinkage resistance of the slurry to the greatest extent.

[0032] As an implementation mode, the mass of the cement can be 75-85% of the total mass of the cement and the coagulant, and can also be 80%; the mass of the coagulant can be 15-25% of the total mass of the cement and the coagulant, and can also be 20-25%.

[0033] In the present invention, the fly ash is preferably first-grade or above fly ash; the particle size of the fly ash preferably satisfies that the sieve residue of a 45 μm square hole sieve is not more than 12%; the mass of the fly ash is preferably 10-20% of the total mass of cement and coagulant. In the present invention, the fly ash has excellent filling capacity and pozzolanic reaction, which can greatly improve the filling property of cementitious material particles and increase the density.

[0034] As an implementation manner, the mass of the fly ash may be 15% of the total mass of the cement and the accelerator.

[0035] In the present invention, the retarder is preferably a solid retarder; the solid retarder is preferably lignin sulfonate; the mass of the retarder is preferably 1-5% of the total mass of cement and accelerator, more preferably 1%. In the present invention, the retarder can ensure that the slurry has sufficient coating and impregnation time.

[0036] In the present invention, the water-cement ratio of the thin slurry is preferably 1.0-1.2, more preferably 1.0. In the present invention, the water-cement ratio determines the thickness of the slurry layer. If the slurry is too thick, the water absorption rate of the aggregate will increase, and if the slurry is too thin, the strengthening effect of the recycled aggregate will be too small, so the water-cement ratio is limited to 1.0-1.2.

[0037] In the present invention, the water-to-solid ratio of the slurry is preferably 5-15%, more preferably 10%. The present invention limits the water-to-solid ratio of the slurry to the above range to improve the strengthening effect of the recycled aggregate.

[0038] The present invention has no particular limitation on the ratio of the recycled aggregate to the slurry, and any amount known to those skilled in the art may be used.

[0039] The present invention has no special limitation on the operation of mixing the recycled aggregate with the slurry, and the technical scheme for preparing the mixed material well known to those skilled in the art can be adopted.

[0040] In the present invention, the impregnation coating is carried out under the conditions of vacuuming and stirring. The present invention improves the coating slurry method, and adopts vacuuming and stirring while the slurry is infiltrated. The vacuuming can extract part of the air in the pores inside the recycled aggregate, and the stirring can increase the degree of air extraction from the pores inside the recycled aggregate, so that the slurry can penetrate into the recycled aggregate to the maximum extent, thereby improving the strengthening effect.

[0041] In the present invention, the vacuum degree of the vacuum pumping is preferably 3.4-4.0 KPa. As an embodiment, the vacuum degree of the vacuum pumping can be 3.5-3.7 KPa. The present invention limits the vacuum degree of the vacuum pumping to the above range to further improve the strengthening effect.

[0042] In the present invention, the stirring speed is preferably 5 to 15 rpm. As an embodiment, the stirring speed may be 10 rpm. In the present invention, limiting the stirring speed within the above range can further improve the strengthening effect.

[0043] In the present invention, the impregnation coating time is preferably 30 to 90 minutes, more preferably 60 minutes; the impregnation coating temperature is preferably not less than 20° C. In the present invention, limiting the impregnation coating time and temperature within the above range can further improve the strengthening effect.

[0044] After the impregnation and coating is completed, the present invention preferably removes the impregnation and coating product from the slurry and then dries it to obtain reinforced recycled aggregate.

[0045] The present invention has no particular limitation on the operation of fishing out the product obtained by impregnation and coating from the slurry, and the operation well known to those skilled in the art can be adopted.

[0046] In the present invention, the drying preferably includes air-drying, curing in a curing room and drying in a oven in sequence.

[0047] In the present invention, the drying is preferably carried out indoors; the drying time is preferably 20 to 30 hours, more preferably 24 hours.

[0048] In the present invention, the curing temperature in the curing room is preferably 19-21° C., more preferably 20° C.; the curing time in the curing room is preferably 5-10 days, more preferably 7 days.

[0049] In the present invention, the drying temperature is preferably 40-60° C., more preferably 50° C. The present invention has no particular limitation on the drying time, and the drying time may be until constant weight.

[0050] The present invention improves the coating slurry method, and adopts vacuuming and stirring while the slurry is infiltrating. The vacuuming can extract part of the air in the pores inside the recycled aggregate, and the stirring can increase the degree of air extraction from the pores inside the recycled aggregate, so that the slurry can penetrate into the recycled aggregate to the greatest extent, thereby improving the strengthening effect.

[0051] The present invention also provides a reinforcing device for recycled aggregate, comprising a negative pressure container and a stirring device arranged in the negative pressure container.

[0052] Figure 1 The reinforcing device for recycled aggregate provided by the present invention, in the figure, 1 is a verification interface, 2 is a pressure regulating device, 3 is a vacuum gauge, 4 is a vacuum pump, 5 is a drying or water accumulation device, 6 is a negative pressure container, 7 is a pressure gauge, and 8 is a stirring device.

[0053] like Figure 1 As shown, the reinforcing device for recycled aggregate provided by the present invention comprises a negative pressure container 6. The present invention has no special limitation on the size of the negative pressure container, which can be adjusted according to actual needs. In the present invention, the negative pressure container is used for impregnation and coating of recycled aggregate.

[0054] like Figure 1 As shown, the reinforcing device for recycled aggregate provided by the present invention further comprises a stirring device 8 disposed in the negative pressure container 6. The present invention has no particular limitation on the type of the stirring device, and any stirring device well known to those skilled in the art may be used.

[0055] like Figure 1 As shown, in one embodiment of the present invention, the reinforcing device for recycled aggregate provided by the present invention further comprises a vacuum gauge 3. The present invention has no special limitation on the position and model of the vacuum gauge, and a vacuum gauge well known to those skilled in the art can be used and the position can be determined according to common technical knowledge.

[0056] like Figure 1 As shown, in one embodiment of the present invention, the reinforcing device for recycled aggregate provided by the present invention further comprises a vacuum pump 4. The present invention has no special limitation on the model and position of the vacuum pump, and a vacuum pump well known to those skilled in the art can be used and the position can be determined according to common technical knowledge.

[0057] like Figure 1 As shown, in one embodiment of the present invention, the reinforcing device for recycled aggregate provided by the present invention further comprises a pressure regulating device 2. The present invention has no special limitation on the pressure regulating device, and the pressure regulating device can be selected according to actual needs.

[0058] like Figure 1 As shown, in one embodiment of the present invention, the reinforcing device for recycled aggregate provided by the present invention further comprises a verification interface 1. The present invention has no special limitation on the position of the verification interface, and the position can be determined by the common sense of those skilled in the art.

[0059] like Figure 1 As shown, in one embodiment of the present invention, the reinforcing device for recycled aggregate provided by the present invention further includes a drying or water accumulation device 5. The present invention has no particular limitation on the size of the drying or water accumulation device, and equipment well known to those skilled in the art can be used. In the present invention, the drying or water accumulation device is used to prevent moisture in the negative pressure container 6 from entering the vacuum pump 4.

[0060] like Figure 1 As shown, in one embodiment of the present invention, the reinforcing device for recycled aggregate provided by the present invention further comprises a pressure gauge 7. The present invention has no special limitation on the model and position of the pressure gauge, and a pressure gauge familiar to those skilled in the art can be used and the position can be determined according to common technical knowledge.

[0061] The strengthening device provided by the present invention is an existing theoretical maximum relative density meter device with a stirring device added thereto, and the existing detection device is used to strengthen the recycled aggregate, thus realizing the application transformation of the device.

[0062] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] Example 1

[0064] The strengthening method of recycled aggregate is as follows:

[0065] (1) Mixing the recycled coarse aggregate of waste concrete obtained by crushing the construction waste crushing station with the dilute slurry, and performing impregnation and coating for 60 minutes under vacuum and stirring conditions, and then fishing out to obtain coated recycled aggregate; wherein the particle size of the recycled coarse aggregate of concrete is 10 to 30 mm; and the impregnation and coating temperature is 25° C.;

[0066] The components of the slurry are 425# cement, coagulant, fly ash, retarder and water; wherein the mass of cement is 80% of the total mass of cement and coagulant; the coagulant is sodium aluminate, the mass of which is 20% of the total mass of cement and coagulant; the first-grade fly ash of fly ash has a particle size that satisfies the 45μm square hole sieve residue of no more than 12%, the mass of which is 15% of the total mass of cement and coagulant; the retarder is lignin sulfonate, the mass of which is 1% of the total mass of cement and coagulant; the water-cement ratio of the slurry is 1.0, and the water-solid ratio is 10%; the vacuum degree of vacuuming is 4.0KPa; the stirring speed is 10rpm;

[0067] (2) The coated recycled aggregate obtained in step (1) is dried indoors for 24 hours, then moved into a 20° C. curing room for 7 days, and then dried at 50° C. to obtain reinforced recycled aggregate.

[0068] Comparative Example 1

[0069] On the basis of Example 1, vacuuming and stirring were omitted, and the mixture was stirred once every 5 minutes during the dipping and coating process, while other conditions remained unchanged.

[0070] Comparative Example 2

[0071] On the basis of Comparative Example 1, the setting accelerator and the setting retarder were omitted, and other conditions remained unchanged.

[0072] The performance of the reinforced recycled aggregate prepared in Example 1 and Comparative Examples 1-2 was tested, and the results are shown in Table 1.

[0073] Table 1 Performance data of reinforced recycled aggregates prepared in Example 1 and Comparative Examples 1-2

[0074] serial number Comparative Example 2 Comparative Example 1 Example 1 Test Standards <![CDATA[Apparent density / (kg / m 3 )]]> 2573 2613 2659 T0304-2024 Crushing value / % 18.26 17.42 15.84 T0316-2024 Water absorption / % 4.95 4.63 3.91 T0307-2005

[0075] It can be seen from Table 1 that the strengthening method provided by the present invention can improve the strengthening effect of recycled aggregate.

[0076] Example 2

[0077] The vacuum degree of the evacuation is 3.4 KPa based on Example 1, and other conditions remain unchanged.

[0078] Comparative Example 3

[0079] The vacuum degree of the evacuation is 2.8 KPa based on Example 1, and other conditions remain unchanged.

[0080] The performance of the reinforced recycled aggregates prepared in Examples 1 to 2 and Comparative Example 3 was tested, and the results are shown in Table 2.

[0081] Table 2 Performance data of reinforced recycled aggregate prepared in Examples 1-2 and Comparative Example 3

[0082] serial number Comparative Example 3 Example 2 Example 1 Test Standards <![CDATA[Apparent density / (kg / m 3 )]]> 2620 2653 2659 T0304-2024 Crushing value / % 17.26 15.92 15.84 T0316-2024 Water absorption / % 4.59 3.98 3.91 T0307-2005

[0083] It can be seen from Table 2 that the vacuum degree of the present invention affects the strengthening effect. At 3.4 KPa, the crushing value and water absorption rate are slightly increased compared with Example 1; at 2.8 KPa, the crushing value increases by 9.0% and the water absorption rate increases by 17.4% compared with Example 1, indicating that as the vacuum degree of the vacuum decreases, the air discharge effect inside the recycled aggregate weakens, and the strengthening effect of the slurry impregnation and coating weakens.

[0084] Example 3

[0085] Based on Example 1, the stirring speed is 15 rpm, and other conditions remain unchanged.

[0086] Comparative Example 4

[0087] On the basis of Example 3, stirring was omitted, and the mixture was stirred once every 5 minutes during the dipping and coating process, while other conditions remained unchanged.

[0088] The performance tests were conducted on the reinforced recycled aggregates prepared in Example 1, Example 3 and Comparative Example 4. The results are shown in Table 3.

[0089] Table 3 Performance data of reinforced recycled aggregates prepared in Example 1, Example 3 and Comparative Example 4

[0090] serial number Comparative Example 4 Example 3 Example 1 Test Standards <![CDATA[Apparent density / (kg / m 3 )]]> 2600 2661 2659 T0304-2024 Crushing value / % 17.58 15.88 15.84 T0316-2024 Water absorption / % 4.61 3.89 3.91 T0307-2005

[0091] It can be seen from Table 3 that the strengthening effect of the stirring speed of 15 rpm is basically the same as that of 10 rpm in Example 1; but compared with Example 3, when stirring is omitted, the crushing value increases by 10.7% and the water absorption rate increases by 18.5%, indicating that stirring helps to discharge the air inside the recycled aggregate and enhances the strengthening effect of the slurry impregnation and coating.

[0092] Example 4

[0093] On the basis of Example 1, the waste concrete recycled coarse aggregate was changed to construction waste recycled aggregate containing 25% red bricks (volume replacement method), and other conditions remained unchanged.

[0094] Comparative Example 5

[0095] On the basis of Example 4, vacuuming and stirring were omitted, and the mixture was stirred once every 5 minutes during the dipping and coating process, while other conditions remained unchanged.

[0096] Comparative Example 6

[0097] On the basis of Comparative Example 5, the setting accelerator and the setting retarder were omitted, and other conditions remained unchanged.

[0098] The performance of the reinforced recycled aggregates prepared in Example 4 and Comparative Examples 5 to 6 was tested, and the results are shown in Table 4.

[0099] Table 4 Performance data of reinforced recycled aggregate prepared in Example 4 and Comparative Examples 5-6

[0100] serial number Comparative Example 6 Comparative Example 5 Example 4 Test Standards <![CDATA[Apparent density / (kg / m 3 )]]> 2353 2384 2432 T0304-2024 Crushing value / % 28.91 25.84 24.86 T0316-2024 Water absorption / % 10.94 9.78 8.53 T0307-2005

[0101] It can be seen from Table 4 that the strengthening method provided by the present invention can improve the strengthening effect of the construction waste recycled aggregate containing 25% red bricks.

[0102] Example 5

[0103] On the basis of Example 1, the waste concrete recycled coarse aggregate was changed to construction waste recycled aggregate containing 50% red bricks (volume replacement method), and other conditions remained unchanged.

[0104] Comparative Example 7

[0105] On the basis of Example 5, vacuuming and stirring were omitted, and the mixture was stirred once every 5 minutes during the dipping and coating process, while other conditions remained unchanged.

[0106] Comparative Example 8

[0107] On the basis of Comparative Example 7, the accelerator and the retarder were omitted, and other conditions remained unchanged.

[0108] The performance tests were conducted on the reinforced recycled aggregates prepared in Example 5 and Comparative Examples 7 to 8. The results are shown in Table 5.

[0109] Table 5 Performance data of reinforced recycled aggregate prepared in Example 5 and Comparative Examples 7-8

[0110] serial number Comparative Example 8 Comparative Example 7 Example 5 Test Standards <![CDATA[Apparent density / (kg / m 3 )]]> 2084 2105 2156 T0304-2024 Crushing value / % 30.91 28.84 26.86 T0316-2024 Water absorption / % 15.98 12.98 11.74 T0307-2005

[0111] It can be seen from Table 5 that the strengthening method provided by the present invention can improve the strengthening effect of the construction waste recycled aggregate containing 50% red bricks.

[0112] It can be seen from the above embodiments and comparative examples that the strengthening method provided by the present invention has excellent strengthening effect.

[0113] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for strengthening recycled aggregate, comprising: The recycled aggregate is mixed with the slurry, and then impregnated and coated to obtain the reinforced recycled aggregate; The impregnation and coating is carried out under vacuum and stirring conditions.

2. The strengthening method according to claim 1, characterized in that: The recycled aggregate includes recycled concrete aggregate and / or recycled aggregate containing red brick construction waste.

3. The strengthening method according to claim 1, characterized in that: The components of the slurry include cement, accelerator, fly ash, retarder and water.

4. The strengthening method according to claim 3, characterized in that: The mass of the coagulant is 30-40% of the total mass of the cement and the coagulant.

5. The strengthening method according to claim 3, characterized in that: The mass of the retarder is 1-5% of the total mass of the cement and the accelerator.

6. The strengthening method according to claim 1, characterized in that: The vacuum degree of the vacuum pumping is 3.4-4.0 KPa.

7. The strengthening method according to claim 1, characterized in that: The stirring speed is 5 to 15 rpm.

8. The strengthening method according to claim 1, characterized in that: The dipping and coating time is 30 to 90 minutes.

9. The strengthening method according to claim 1 or 8, characterized in that: The dipping and coating time is 60 minutes.

10. A device for reinforcing recycled aggregates, comprising a negative pressure container and a stirring device arranged in the negative pressure container.

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