CN113117862A - Method for quickly removing mortar attached to coarse aggregate of recycled concrete - Google Patents
Method for quickly removing mortar attached to coarse aggregate of recycled concrete Download PDFInfo
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- CN113117862A CN113117862A CN202110417004.XA CN202110417004A CN113117862A CN 113117862 A CN113117862 A CN 113117862A CN 202110417004 A CN202110417004 A CN 202110417004A CN 113117862 A CN113117862 A CN 113117862A
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- aggregate
- coarse aggregate
- concrete
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C21/00—Disintegrating plant with or without drying of the material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C19/00—Other disintegrating devices or methods
- B02C19/18—Use of auxiliary physical effects, e.g. ultrasonics, irradiation, for disintegrating
- B02C19/186—Use of cold or heat for disintegrating
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
- B02C23/08—Separating or sorting of material, associated with crushing or disintegrating
- B02C23/14—Separating or sorting of material, associated with crushing or disintegrating with more than one separator
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B7/00—Combinations of wet processes or apparatus with other processes or apparatus, e.g. for dressing ores or garbage
Abstract
The invention discloses a method for quickly removing mortar attached to coarse aggregate of recycled concrete, which comprises the following steps: primary impurity removal, crushing, high-temperature deterioration, soaking in saturated water, freeze thawing and peeling, vibration screening, mechanical vibration, high-pressure washing and secondary impurity removal. The method for removing the adhesive mortar has low energy consumption, hardly causes pollution to the environment, does not damage internal natural aggregate, and is beneficial to realizing large-scale industrial production; in addition, the preparation method can remove the mortar more thoroughly, and the properties of the prepared recycled coarse aggregate are closer to those of natural aggregate, so that the recycled coarse aggregate can be used for producing high-strength concrete.
Description
Technical Field
The invention relates to the technical field of concrete structure waste material recycling, in particular to a method for removing recycled concrete coarse aggregate adhering mortar based on high-temperature degradation and freeze-thaw cleavage coupling effect.
Background
At present, China is in the peak period of economic development and infrastructure construction, urban and rural construction and old city transformation are promoted in a large range, and a large number of buildings are dismantled and rebuilt even if the design service life is not reached. The demolition of the existing buildings inevitably generates a large amount of construction waste; meanwhile, the reconstruction also consumes a large amount of natural aggregate which is an irreproducible resource, and the exploitation of a large amount of natural aggregate can cause serious damage to the environment. The waste concrete is usually disposed of in a landfill mode, and the disposal mode has a plurality of disadvantages, such as occupying a large amount of landfill land.
With the improvement of environmental awareness and the increasing shortage of resources, the recycling of waste concrete becomes a focus of attention of people, and the recycled coarse aggregate and the recycled concrete gradually become research hotspots in academic circles and engineering circles. Waste concrete has been tried to be added as coarse aggregate to fresh concrete, but the old mortar attached thereto has a strong negative effect on the concrete to be cast.
The existing techniques for modifying recycled aggregate can be roughly divided into three categories according to different methods: 1) adjusting the mixing ratio; 2) removing old mortar attached to the recycled coarse aggregate through aggregate treatment; 3) and (4) strengthening the old mortar.
CN 108675662A discloses a recycled aggregate freeze-thaw cycle pretreatment method, which specifically comprises the steps of primary crushing, impurity removal, soaking, freeze-thaw cycle, secondary crushing, cleaning and polishing, and screening. After the freeze-thaw cycle pretreatment, the expansion pressure generated on the inner wall of the concrete pore when water is frozen is utilized to enable the concrete to generate cracks from the weak part inside; after the ice is formed into water, the water can go deep into the interior of the structure through the crack
CN 10855825A discloses a method for separating regenerated coarse aggregate old mortar, which comprises the following steps: crushing the waste concrete to obtain a regenerated coarse aggregate; performing multiple circulating freeze-thaw experiments after the recycled coarse aggregate is saturated by absorbing water; after the freeze-thaw experiment is finished, stirring at a high speed to remove old mortar; and detecting the content of the old mortar in the obtained coarse aggregate, and repeating the experiment if the old mortar is unqualified until the content of the old mortar is less than or equal to 5 percent to obtain the qualified recycled coarse aggregate.
The common techniques for removing old mortar mainly include acid washing and mechanical removal, however, these methods cause great pollution to the environment and remove the adhering mortar insufficiently, and have more limitations.
Disclosure of Invention
The invention aims to provide a preparation method for efficiently removing old mortar attached to recycled concrete aggregate to obtain recycled aggregate with various performances closer to those of natural aggregate. By utilizing the preparation method, the problems of low strength and other properties of the recycled concrete, limited cycle times and the like caused by old mortar attached to the recycled aggregate in the waste concrete can be solved. The invention utilizes the coupling effect of high-temperature deterioration and freeze-thaw damage, can rapidly and completely strip the adhesive mortar from the recycled concrete aggregate, and produces the recycled coarse aggregate with the performance similar to the original natural coarse aggregate, and simultaneously reduces the energy consumption as much as possible and increases the recycling times of the recycled aggregate.
The technical scheme provided by the invention for solving the technical problems is as follows:
a method for quickly removing old mortar attached to recycled concrete coarse aggregate comprises the following steps: primary impurity removal, crushing, high-temperature deterioration, soaking in saturated water, freeze thawing and peeling, vibration screening, mechanical vibration, high-pressure washing and secondary impurity removal.
The method for removing the mortar attached to the recycled concrete aggregate is based on high-temperature deterioration and freeze-thaw cleavage coupling effect, the weakest link of each component of the concrete under freezing effect is a transition area of an aggregate mortar interface, the mortar is inferior in body, the damage of the aggregate can be ignored, and the damage is gradually accumulated through the expansion effect of water during freezing, so that the wrapped mortar block is crushed and stripped from the aggregate; meanwhile, high-temperature deterioration is introduced, the regenerated aggregate cement matrix is dehydrated and becomes brittle, the bonding capability is reduced, and the stripping efficiency of old mortar is accelerated; finally removing the adhering mortar to prepare the recycled coarse aggregate with the performance close to that of the natural aggregate.
The method comprises the following specific steps:
s1, primary impurity removal: removing non-construction waste and large brickwork in the concrete blocks;
s2, crushing: crushing the concrete blocks into concrete fragments;
s3, high temperature degradation: carrying out high-temperature deterioration treatment on the concrete fragments;
s4, soaking in water: soaking the concrete blocks subjected to high-temperature degradation treatment into water for water saturation;
s5, freeze-thaw peeling: carrying out freeze-thaw cycle treatment on the concrete fragments subjected to water saturation treatment;
s6, vibrating and screening: carrying out vibration screening on the recycled coarse aggregate subjected to freeze thawing for certain times of freeze thawing cycle treatment, and screening out the peeled adhesive mortar;
s7, mechanically vibrating: placing the screened recycled concrete coarse aggregate into a roller stone washer for mechanical vibration operation, so that the melted recycled concrete coarse aggregate rolls and collides in the roller, the adhered mortar is fully peeled off, and the damage of an internal weak surface is aggravated;
s8, high-pressure flushing: washing the recycled concrete coarse aggregate subjected to mechanical vibration at high pressure by using a high-pressure water gun;
s9, repeating the steps S5-S8 for 1-3 times;
s10, repeating the steps S3-S8 for 1 time;
s11, repeating the steps S5-S8 for 1-3 times;
and S12, secondary impurity removal, namely removing non-aggregate substances to obtain the recycled coarse aggregate after the adhesive mortar is completely removed.
The particle size of the concrete fragments is less than or equal to 37.5 mm.
The concrete fragments are obtained by crushing through a jaw crusher and a cone crusher.
The high temperature deterioration temperature is above 80 ℃, and the high temperature deterioration time depends on the specific deterioration temperature and the saturation degree of the aggregate; preferably 80 to 200 ℃ and the deterioration time is 24 to 72 hours.
The water saturation time is 2-4 days.
The cycle times of each round of freeze-thaw cycle operation are 4-6 times, the freeze-thaw cycle is in the form of water freezing and water thawing, the minimum freeze-thaw retention temperature is-25 ℃ to-15 ℃, and the maximum freeze-thaw retention temperature is 15-20 ℃.
The water freezing and water melting is to immerse the waste concrete blocks in water, directly freeze and melt the water, the highest temperature is preferably higher than 15 ℃, the lowest temperature is preferably lower than minus 15 ℃, and under the action of total pore pressure formed by water pressure, crystallization pressure and low-temperature suction, microcracks in the attached mortar are increased, so that the attached mortar is peeled off.
The rotating speed of the roller stone washer is 40-80 revolutions per minute, and the running time of the roller stone washer is 20-60 seconds.
After each mechanical vibration, the aggregate is placed on a conveying belt which can enable the aggregate to roll in the conveying process, high-pressure water guns are arranged at certain intervals, and the aggregate is washed at high pressure in the conveying process. In the high-pressure squirt washes the operation, the high-pressure squirt should evenly arrange along certain length of conveyer belt, can wash the mortar that peels off on aggregate surface and further aggravate the damage to the old mortar that does not peel off.
The non-aggregate material is masonry fragments and ceramic tiles. And performing secondary impurity removal on the obtained recycled coarse aggregate, wherein non-aggregate impurities such as masonry fragments and ceramic tiles which are easier to distinguish are mainly removed, so that purer recycled coarse aggregate is obtained.
Compared with the prior art, the invention has the following beneficial effects:
1. the traditional methods for removing old mortar include acid washing, mechanical grinding and the like, and the methods have high energy consumption, great environmental pollution, great damage to aggregate and great influence of the wrapping mode of old mortar. Compared with the traditional method for removing the mortar, the process has low energy consumption, hardly causes pollution to the environment, does not damage aggregate and is beneficial to realizing large-scale industrial production.
2. The process can realize the reutilization of water.
3. The mortar is removed more thoroughly.
4. The obtained recycled aggregate has low powder content.
5. The recycled aggregate prepared by the process has various properties more similar to those of the original natural aggregate.
6. The prepared recycled aggregate can be used for producing high-strength concrete.
Drawings
FIG. 1 is a process flow diagram.
FIG. 2 shows recycled aggregate prepared in example 1.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Referring to the process flow chart shown in fig. 1, quickly removing the mortar attached to the recycled concrete coarse aggregate to prepare the recycled coarse aggregate:
1. carrying out primary impurity removal on the waste building rubbish to remove non-concrete building rubbish easy to separate;
2. then crushing the waste concrete blocks by using a jaw crusher and a cone crusher, and crushing the waste concrete blocks into waste concrete fragments with the particle size of less than 37.5 mm;
3. placing the crushed waste concrete blocks at a constant temperature of 200 ℃ for high-temperature degradation for 12 hours;
4. soaking the prepared waste concrete blocks into water for saturation;
5. after three days of soaking, performing freeze-thaw cycle on the waste concrete fragments for 5 times, wherein the freeze-thaw cycle is water-thaw, the minimum freeze-thaw keeping temperature is minus 20 ℃, and the maximum temperature is 15 ℃;
6. after each 5 times of freeze-thaw cycle, carrying out vibration screening on the waste aggregate, and screening out the peeled adhesive mortar;
7. then carrying out rolling collision on the aggregates for 30s at the speed of 50 revolutions per minute by using a roller stone washer;
8. carrying out high-pressure washing on the aggregate treated in the previous step by using a high-pressure water gun;
9. then repeating the operation of 5-8 on the aggregate;
10. after 10 times of freeze-thaw cycles, putting the aggregate in the constant temperature of 200 ℃ again for secondary high-temperature degradation;
11. then, saturating the aggregate with water and repeating the operation of 5-8 times;
12. and (3) removing impurities for the second time to remove non-aggregate substances in the prepared recycled coarse aggregate, such as building wastes like crushed brickwork and ceramic tiles, and finally preparing the recycled coarse aggregate with the performance close to that of natural aggregate shown in the figure 2.
Control group
The recycled coarse aggregate of the control group was prepared in the same manner as in example 1, except that the control group was not subjected to the high-temperature deterioration treatment.
And (3) testing results:
1. the crushing index and the mass water absorption of the untreated recycled concrete aggregate, the control group and the material of example 1 were determined according to the specifications GB/T14685-2011 construction pebbles, macadam, respectively. The results are shown in Table 1.
TABLE 1
| Serial number | Crush index | Mass water absorption |
| Untreated recycled concrete aggregate | 18.6％ | 7.31％ |
| Control group | 15.78％ | 6.43％ |
| Example 1 | 6.52％ | 1.35％ |
Claims (10)
1. A method for quickly removing mortar attached to recycled concrete coarse aggregate is characterized by comprising the following steps: primary impurity removal, crushing, high-temperature deterioration, soaking in saturated water, freeze thawing and peeling, vibration screening, mechanical vibration, high-pressure washing and secondary impurity removal.
2. The method of claim 1, comprising the steps of:
s1, primary impurity removal: removing non-construction waste and large brickwork in the concrete blocks;
s2, crushing: crushing the concrete blocks into concrete fragments;
s3, high temperature degradation: carrying out high-temperature deterioration treatment on the concrete fragments;
s4, soaking in water: soaking the concrete blocks subjected to high-temperature degradation treatment into water for water saturation;
s5, freeze-thaw peeling: carrying out freeze-thaw cycle treatment on the concrete fragments saturated with water to obtain treated recycled coarse aggregate;
s6, vibrating and screening: carrying out vibration screening on the recycled coarse aggregate subjected to freeze-thaw cycle treatment, and screening out the peeled adhesive mortar;
s7, mechanically vibrating; placing the screened recycled coarse aggregate into a roller stone washer for mechanical vibration operation, so that the recycled coarse aggregate rolls and collides in the roller, the attached mortar is fully peeled off, and the damage of an internal weak surface is aggravated;
s8, high-pressure flushing: washing the mechanically vibrated recycled coarse aggregate at high pressure by using a high-pressure water gun;
s9, repeating the steps S5-S8 for 1-3 times;
s10, repeating the steps S3-S8 for 1 time;
s11, repeating the steps S5-S8 for 1-3 times;
s12, secondary impurity removal: and removing non-aggregate substances to obtain the recycled coarse aggregate after the adhering mortar is completely removed.
3. A method according to claim 2, wherein the particle size of the concrete pieces is 37.5mm or less.
4. The method according to claim 2, characterized in that the concrete fragments are obtained by crushing with a jaw crusher and a cone crusher.
5. The method according to claim 1 or 2, wherein the high temperature degradation temperature is 80 ℃ to 200 ℃ and the degradation time is 24h to 72 h.
6. The method according to claim 1 or 2, wherein the water saturation time is 2-4 days.
7. The method according to claim 1 or 2, wherein the number of cycles of the freeze-thaw cycle is 4-6, the freeze-thaw cycle is in the form of water thawing, the minimum freeze-thaw retention temperature is-25 ℃ to-15 ℃, and the maximum freeze-thaw retention temperature is 15-20 ℃.
8. The method according to claim 1 or 2, wherein the rotation speed of the roller stone washer is 40-60 revolutions per minute, and the running time of the roller stone washer is 20-40 seconds.
9. A method according to claim 1 or 2, characterized in that after each mechanical vibration treatment, the aggregates are placed on a conveyor belt which allows the aggregates to roll during the conveying process, and that high-pressure water guns are arranged at regular intervals for high-pressure flushing of the aggregates during the conveying process.
10. A method according to claim 2, wherein the non-aggregate material is masonry fragments, tiles or the like.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114178303A (en) * | 2021-11-25 | 2022-03-15 | 中冶南方都市环保工程技术股份有限公司 | Crushing and washing integrated repair system suitable for polluted construction slag and repair method thereof |
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| JPH0354137A (en) * | 1989-07-21 | 1991-03-08 | Toda Constr Co Ltd | Reuse of concrete taken to piece |
| CN101624274A (en) * | 2009-08-07 | 2010-01-13 | 武汉理工大学 | Method for preparing asphalt pavement material by adopting waste concrete |
| CN104761169A (en) * | 2015-04-27 | 2015-07-08 | 河南城建学院 | Freezing reclamation method for waste concrete |
| CN108558255A (en) * | 2018-05-23 | 2018-09-21 | 河南理工大学 | The separation method of old mortar in a kind of regenerated coarse aggregate |
| CN108675662A (en) * | 2018-06-04 | 2018-10-19 | 安徽理工大学 | A kind of recycled aggregate Frozen-thawed cycled preprocess method |
| CN110922078A (en) * | 2019-11-13 | 2020-03-27 | 西安理工大学 | Method for improving quality of recycled coarse aggregate by adopting sulfate erosion-freeze thawing cycle |
-
2021
- 2021-04-12 CN CN202110417004.XA patent/CN113117862B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0354137A (en) * | 1989-07-21 | 1991-03-08 | Toda Constr Co Ltd | Reuse of concrete taken to piece |
| CN101624274A (en) * | 2009-08-07 | 2010-01-13 | 武汉理工大学 | Method for preparing asphalt pavement material by adopting waste concrete |
| CN104761169A (en) * | 2015-04-27 | 2015-07-08 | 河南城建学院 | Freezing reclamation method for waste concrete |
| CN108558255A (en) * | 2018-05-23 | 2018-09-21 | 河南理工大学 | The separation method of old mortar in a kind of regenerated coarse aggregate |
| CN108675662A (en) * | 2018-06-04 | 2018-10-19 | 安徽理工大学 | A kind of recycled aggregate Frozen-thawed cycled preprocess method |
| CN110922078A (en) * | 2019-11-13 | 2020-03-27 | 西安理工大学 | Method for improving quality of recycled coarse aggregate by adopting sulfate erosion-freeze thawing cycle |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114178303A (en) * | 2021-11-25 | 2022-03-15 | 中冶南方都市环保工程技术股份有限公司 | Crushing and washing integrated repair system suitable for polluted construction slag and repair method thereof |
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| CN113117862B (en) | 2022-06-10 |
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