CN116693225B - Method for removing weak layers of recycled aggregate old mortar - Google Patents
Method for removing weak layers of recycled aggregate old mortar Download PDFInfo
- Publication number
- CN116693225B CN116693225B CN202310660699.3A CN202310660699A CN116693225B CN 116693225 B CN116693225 B CN 116693225B CN 202310660699 A CN202310660699 A CN 202310660699A CN 116693225 B CN116693225 B CN 116693225B
- Authority
- CN
- China
- Prior art keywords
- recycled aggregate
- aggregate
- old mortar
- mortar
- recycled
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000004570 mortar (masonry) Substances 0.000 title claims abstract description 102
- 238000000034 method Methods 0.000 title claims abstract description 40
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims abstract description 48
- 239000004567 concrete Substances 0.000 claims abstract description 42
- 238000002791 soaking Methods 0.000 claims abstract description 38
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000000126 substance Substances 0.000 claims abstract description 10
- 230000008569 process Effects 0.000 claims abstract description 7
- 230000004927 fusion Effects 0.000 claims abstract description 5
- 238000009738 saturating Methods 0.000 claims abstract description 5
- 238000007873 sieving Methods 0.000 claims abstract description 5
- 125000004122 cyclic group Chemical group 0.000 claims abstract description 3
- 239000004568 cement Substances 0.000 claims description 18
- 239000000243 solution Substances 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 230000009471 action Effects 0.000 claims description 10
- 239000003795 chemical substances by application Substances 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 8
- 229910001653 ettringite Inorganic materials 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 6
- 239000000654 additive Substances 0.000 claims description 5
- 230000000996 additive effect Effects 0.000 claims description 5
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 5
- 239000011707 mineral Substances 0.000 claims description 5
- 238000002360 preparation method Methods 0.000 claims description 5
- 239000013078 crystal Substances 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 230000000737 periodic effect Effects 0.000 claims description 3
- 239000011148 porous material Substances 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 2
- 239000004566 building material Substances 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 9
- 239000004575 stone Substances 0.000 description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 239000004576 sand Substances 0.000 description 5
- 239000003153 chemical reaction reagent Substances 0.000 description 4
- 238000010276 construction Methods 0.000 description 4
- 230000007246 mechanism Effects 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 230000007704 transition Effects 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 3
- 239000000428 dust Substances 0.000 description 2
- 230000036571 hydration Effects 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 235000019738 Limestone Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000029087 digestion Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 235000019441 ethanol Nutrition 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 239000010438 granite Substances 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 229910021487 silica fume Inorganic materials 0.000 description 1
- 239000003469 silicate cement Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/02—Treatment
- C04B20/026—Comminuting, e.g. by grinding or breaking; Defibrillating fibres other than asbestos
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/04—Waste materials; Refuse
- C04B18/16—Waste materials; Refuse from building or ceramic industry
- C04B18/167—Recycled materials, i.e. waste materials reused in the production of the same materials
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/02—Treatment
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/02—Treatment
- C04B20/023—Chemical treatment
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Civil Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention belongs to the field of building materials, and provides a method for removing a weak layer of recycled aggregate old mortar, which comprises the steps of crushing concrete to obtain recycled aggregate; putting the recycled aggregate into isopropanol solution for soaking saturation, and taking out to obtain initial recycled aggregate; the initial recycled aggregate is put into absolute ethyl alcohol solution for soaking saturation and then taken out, and intermediate recycled aggregate is obtained; placing the intermediate recycled aggregate into a mixed fusion solution of isopropanol and absolute ethyl alcohol, soaking and saturating, and taking out to obtain the treated recycled aggregate; taking the three soaking processes as a period, and periodically and repeatedly soaking until deformation cracks appear at the interface of the old mortar and the recycled aggregate to obtain the recycled aggregate with cracks; and sieving the recycled aggregate with the cracks to obtain the aggregate with weak mortar removed, and realizing the effective removal of the recycled aggregate old mortar. The method utilizes a chemical method for cyclic treatment for a certain period to lead the aggregate and the old mortar to generate deformation incompatibility, and the old mortar naturally falls off from the surface of the aggregate.
Description
Technical Field
The invention belongs to the technical field of building materials, and particularly relates to a method for removing a weak layer of recycled aggregate old mortar.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The concrete infrastructure is large in body quantity, along with the service life of the infrastructure approaching the service design life, a large number of concrete structures are dismantled, the disposal of construction waste is a problem to be solved urgently, the burying of the construction waste causes pollution to the ecological environment, the dismantled concrete is recycled after being crushed, the digestion of the construction waste can be realized, and the low-carbon development of the building industry is assisted.
The recycled aggregate is prepared after demolished concrete is crushed, the recycled aggregate generally contains coarse aggregate and old mortar, the porosity of the old mortar is high relative to that of the recycled aggregate, the strength of the old mortar is low, the interface between the aggregate and the old mortar in the recycled aggregate belongs to weak phases, the construction performance and mechanical performance of the concrete are affected when the concrete is prepared, the weak constraint performance of the interface transition area of the recycled aggregate is improved, the old interface transition area cannot be removed at all by the interface transition area strengthening method, the old mortar layer on the surface of the recycled aggregate is treated to be thinner along with the improvement of the crushing process, but the mortar layer of the recycled aggregate is difficult to remove fundamentally, and the crushing of the recycled aggregate is difficult to effectively remove the old mortar on the aggregate from essence. The mortar on the surface of the recycled aggregate increases the interface transition area of the aggregate and the old mortar, and in addition, the mortar of the recycled aggregate is porous relative to the aggregate, and can suck a certain amount of water from the surrounding cement paste, thereby influencing the interface of the recycled aggregate and the concrete. Therefore, the old mortar on the surface of the recycled aggregate severely restricts the improvement of the recycled aggregate concrete performance. In order to fully exert the performance of the recycled aggregate, the old mortar weak layer on the surface of the recycled aggregate needs to be removed.
The existing old mortar weak layer removing method is mainly characterized in that broken aggregates are processed through mechanical equipment, and old mortar on the surface of the recycled aggregates is removed through friction between the aggregates and the self or the side wall of the mechanical equipment. The mechanical equipment is operated to remove the old mortar weak layer to generate dust, noise and other pollution, and the old mortar weak layer is not removed thoroughly.
Disclosure of Invention
In order to solve the problems, the invention provides a method for removing the old mortar weak layer of recycled aggregate, and aims to solve the problem of thoroughly removing the old mortar weak layer on the surface of the recycled aggregate.
According to some embodiments, the scheme of the invention provides a method for removing a weak layer of recycled aggregate old mortar, which adopts the following technical scheme:
a method for removing a weak layer of recycled aggregate old mortar comprises the following steps:
crushing the concrete to obtain recycled aggregate;
putting the recycled aggregate into isopropanol solution for soaking saturation, and taking out to obtain initial recycled aggregate;
the initial recycled aggregate is put into absolute ethyl alcohol solution for soaking saturation and then taken out, and intermediate recycled aggregate is obtained;
placing the intermediate recycled aggregate into a mixed fusion solution of isopropanol and absolute ethyl alcohol, soaking and saturating, and taking out to obtain the treated recycled aggregate;
taking the three soaking processes as a period, and periodically and repeatedly soaking until deformation cracks appear at the interface of the old mortar and the recycled aggregate to obtain the recycled aggregate with cracks;
and sieving the recycled aggregate with the cracks to obtain the aggregate with weak mortar removed, and realizing the effective removal of the recycled aggregate old mortar.
Further, the preparation flow of the concrete is as follows:
mixing and stirring cement, water, fine aggregate, coarse aggregate and minerals for 3-5 min, adding the chemical additive into the mixture three times in equal amount, and stirring for 6-10 min in the whole course to obtain the concrete for preparing the recycled aggregate.
Further, the chemical additive is an expanding agent, wherein the mass fraction of CaO and CSA components is 20-35% and 35-45%.
Further, for periodic repeated soaking, the longer the age of the concrete, the longer the cycle period.
Further, putting the recycled aggregate into isopropanol solution for soaking saturation, and then taking out to obtain the initial recycled aggregate, wherein the method specifically comprises the following steps:
immersing the recycled aggregate into isopropanol solution completely, immersing for 6-10 days, taking out and naturally airing to obtain the initial recycled aggregate.
Further, the initial recycled aggregate is put into absolute ethanol solution for soaking saturation and then is taken out, and the intermediate recycled aggregate is obtained, specifically:
immersing the initial recycled aggregate in absolute ethanol solution for 5-8 days, taking out and naturally airing to obtain the intermediate recycled aggregate.
Further, placing the intermediate recycled aggregate into a mixed fusion solution of isopropanol and absolute ethyl alcohol, soaking and saturating, and taking out to obtain the treated recycled aggregate, wherein the method specifically comprises the following steps:
and (3) putting the intermediate recycled aggregate into a mixed solution of isopropanol and absolute ethyl alcohol in a mass ratio of 1:1, soaking for 4-7 days, taking out, and naturally airing to obtain the treated recycled aggregate.
Further, for concrete in different ages, as the cycle period increases, old mortar ettringite in recycled aggregate is dehydrated to deform the aggregate and the old mortar, the recycled aggregate and the old mortar interface generate stress, and cracks appear on the surface of the recycled aggregate under the action of the stress and become larger and larger, so that the old mortar naturally falls off from the surface of the aggregate.
Further, the recycled aggregate comprises coarse aggregate and old mortar.
Further, crushing the concrete by using a jaw crusher to obtain recycled aggregate.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, the cyclic treatment of a certain period by a chemical method is utilized to ensure that the pore space of the aggregate is compact and cannot generate volume deformation, the ettringite in the cement stone phase of the old mortar loses crystal water, the volume is reduced, the deformation of the aggregate and the old mortar is uncoordinated, the regenerated aggregate-old mortar interface generates stress, microcracks are generated and expanded at the aggregate-old mortar interface under the action of the stress until the microcracks are penetrated, and the old mortar naturally falls off from the surface of the aggregate.
The invention can thoroughly remove the old mortar weak layer on the surface of the recycled aggregate; the method for removing the weak layer of the old mortar can not produce negative effects of noise, dust and the like polluting the environment; the recycled aggregate performance obtained by separation through chemical action is superior to that obtained by physical action, and the waste mortar is separated from the aggregate by utilizing ettringite to lose water and shrink volume to cause the deformation of the aggregate and the old mortar to be inconsistent, so that the stress concentration of the aggregate-old mortar interface is cracked, and the old mortar is separated from the aggregate.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
FIG. 1 is a flow chart of a method for removing a weak layer of recycled aggregate old mortar in an embodiment of the invention;
FIG. 2 is a schematic diagram of a separation mechanism of a weak layer of old mortar on the surface of recycled aggregate in the embodiment of the invention;
FIG. 3 is a view showing a state of the surface of recycled aggregate before surface removal in the embodiment of the invention;
FIG. 4 is a surface state diagram of a recycled aggregate surface immersed for 2 cycles in an embodiment of the present invention;
FIG. 5 is a surface state diagram of a recycled aggregate surface immersed for 4 cycles in an embodiment of the present invention;
FIG. 6 is a diagram of the swelling agent hydration product in an embodiment of the present invention;
FIG. 7 is a schematic diagram showing the development of cement stone cracks after the recycled aggregate is soaked for different periods in the embodiment of the invention;
FIG. 8 is a schematic diagram showing the development of cracks at the interface of the aggregate and the cement stone after the recycled aggregate is soaked for different periods in the embodiment of the invention;
FIG. 9 is a diagram of a recycled aggregate old mortar before removal in an embodiment of the invention;
fig. 10 is a diagram of a recycled aggregate used mortar removed according to an embodiment of the present invention.
Detailed Description
The invention will be further described with reference to the drawings and examples.
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
Embodiments of the invention and features of the embodiments may be combined with each other without conflict.
Example 1
As shown in fig. 1, this embodiment provides a method for removing a weak layer of recycled aggregate old mortar. In this embodiment, the method includes the steps of:
crushing the concrete to obtain recycled aggregate;
putting the recycled aggregate into isopropanol solution for soaking saturation, and taking out to obtain initial recycled aggregate;
the initial recycled aggregate is put into absolute ethyl alcohol solution for soaking saturation and then taken out, and intermediate recycled aggregate is obtained;
placing the intermediate recycled aggregate into a mixed fusion solution of isopropanol and absolute ethyl alcohol, soaking and saturating, and taking out to obtain the treated recycled aggregate;
taking the three soaking processes as a period, and periodically and repeatedly soaking until deformation cracks appear at the interface of the old mortar and the recycled aggregate to obtain the recycled aggregate with cracks;
and sieving the recycled aggregate with the cracks to obtain the aggregate with weak mortar removed, and realizing the effective removal of the recycled aggregate old mortar.
For concrete in different ages, as the cycle period increases, old mortar ettringite in recycled aggregate loses water to deform the aggregate and the old mortar, the recycled aggregate and the old mortar interface generate stress, and cracks appear on the surface of the recycled aggregate under the action of the stress and become larger and larger, so that the old mortar naturally falls off from the surface of the aggregate.
The concrete refers to the concrete which is not crushed after being prepared and molded; after the concrete is crushed, the concrete is formed into particles, the recycled aggregate is called as aggregate containing aggregate and mortar, and the concrete prepared from the recycled aggregate is called as recycled aggregate concrete.
The method of the embodiment specifically includes:
separation of old mortar weak layer on surface of recycled aggregate
(1) Crushing the concrete by a jaw crusher to form recycled aggregate, wherein the particle size of the recycled aggregate is 10-30 mm;
(2) Immersing the recycled aggregate in isopropanol completely for 6-10 days, taking out and naturally airing;
soaking in absolute ethyl alcohol for 5-8 days, taking out and naturally airing;
then immersing the mixture in a mixed reagent of isopropanol and absolute ethyl alcohol in a mass ratio of 1:1 for 4-7 days, taking out and naturally airing; the method is carried out periodically and repeatedly by taking the method as one period, wherein the method is used for circulating for 2-5 periods for 7-day-age concrete, 4-10 periods for 28-day-age concrete and 6-18 periods for age concrete exceeding one year.
The longer the concrete age, the longer the corresponding soaking period.
(3) And sieving the recycled aggregate with a sieve aperture of 5-10 mm to obtain the aggregate with weak mortar removed, and realizing effective removal of the recycled aggregate and old mortar.
Wherein, the concrete for preparing the recycled aggregate
The concrete for preparing the recycled aggregate comprises, by mass, 320-400 parts of water, 180-240 parts of cement, 650-820 parts of fine aggregate, 900-1300 parts of coarse aggregate, 30-100 parts of mineral admixture and 15-30 parts of chemical admixture.
The water is tap water or deionized water;
the cement is ordinary silicate cement;
the fine aggregate is river sand or machine-made sand;
the coarse aggregate is granite, limestone and quartz stone crushed stone;
the mineral admixture is one or more of fly ash, silica fume, slag and the like;
the chemical additive is an expanding agent, wherein the mass fraction of CaO and CSA components is 20-35% and 35-45%.
The preparation process comprises the following steps:
mixing and stirring the cement, the water, the fine aggregate, the coarse aggregate and the mineral admixture for 3-5 min, adding the chemical admixture into the mixture in three equal amounts, and stirring for 6-10 min in the whole process.
The prepared concrete is crushed after being dismantled to obtain recycled aggregate, wherein the recycled aggregate comprises coarse aggregate and old mortar, and the particle size of the recycled aggregate is 10-30 mm.
The separation mechanism diagram of the weak layer of the used mortar on the surface of the recycled aggregate is shown in fig. 2, the pore of the aggregate is compact, the volume deformation does not occur, the ettringite in the cement stone phase of the used mortar loses crystal water, the volume is reduced, the deformation of the aggregate and the used mortar is uncoordinated, the recycled aggregate-used mortar interface generates stress, microcracks are generated and expanded at the aggregate-used mortar interface under the action of the stress until the microcracks are penetrated, and the used mortar naturally falls off from the surface of the aggregate. The stress concentration of the recycled aggregate-old mortar interface is increased through the uncoordinated deformation of the recycled aggregate and the old mortar phase, cracks are generated, and the two-phase separation is realized.
Example 1
The preparation proportion of the recycled aggregate is designed, the consumption of water, cement, sand, coarse aggregate and expanding agent is 210 parts, 304-parts, 709 parts, 1157 parts and 20 parts respectively, and the prepared concrete is subjected to mechanical action of a jaw crusher for 7 days to obtain the recycled aggregate. Before the recycled aggregate is immersed in isopropanol and absolute ethyl alcohol, as shown in fig. 3, no crack is formed on the surface, the recycled aggregate is completely immersed in isopropanol for 6 days, and the recycled aggregate is taken out and naturally dried; soaking in absolute ethanol for 5 days, taking out, and naturally airing; immersing the recycled aggregate into a mixed reagent with the mass ratio of isopropanol to absolute ethyl alcohol of 1:1 for 5 days, taking out the recycled aggregate and naturally airing the recycled aggregate, taking the recycled aggregate as one period, and periodically repeating the steps, wherein for the concrete with the age of 7 days, after 2 periods of circulation, the recycled aggregate surface state is shown in fig. 4, the old mortar is cracked and dispersed cracks appear, after the soaking period is increased to 4 periods, the recycled aggregate surface state is shown in fig. 5, the old mortar is provided with a plurality of main cracks, and after five periods of soaking, the recycled aggregate surface mortar naturally falls off to obtain the recycled aggregate after the weak mortar is removed.
Example 2
In order to investigate the release mechanism of the recycled aggregate and the weak mortar, the concrete is prepared by adopting the water, cement, sand, coarse aggregate and expanding agent with the dosages of 190 parts, 356 parts, 689 parts, 1125 parts and 40 parts respectively, and the recycled aggregate is obtained after curing for 28 days through the mechanical action of a jaw crusher. Immersing the recycled aggregate in isopropanol completely for 10 days, taking out and naturally airing; soaking in absolute ethanol for 8 days, taking out, and naturally airing; then immersing the mixture in a mixed reagent with the mass ratio of isopropanol to absolute ethanol being 1:1 for 7 days, taking out and naturally airing, taking the mixture as a period, and carrying out periodical repetition. The observation of the microscopic morphology of the concrete is shown in fig. 6, after the hydration product of the expanding agent and the alcohol are observed, the volume of the water release shape change is retracted, the crack appears in the cement stone firstly, as shown in fig. 7, after 3 periods of soaking, the cement stone appears in a crack, the number of cracks of the cement stone is increased along with the increase of the soaking times to 6 periods, the cracks are overlapped, and the cracks are widened along with the increase of the circulating times. As shown in FIG. 8, when the back scattering image observation is carried out on concrete polishing, cement cracks develop to the interface of the aggregate and the old mortar when the soaking period is 6 times, the number of cracks between the aggregate and the old mortar is increased and gradually overlapped to form a net along with the increase of the soaking times, the soaking period is increased to 14 times through the development, the cracks of the aggregate and the old mortar are through the development, the recycled aggregate and the old mortar are separated, and the action mechanism of the method is revealed from the microscopic level, so that the feasibility of the method is proved.
Example 3
The preparation proportion of the recycled aggregate is designed, the dosages of water, cement, sand, coarse aggregate and expanding agent are 190 parts, 302 parts, 715 parts, 1167 parts and 26 parts respectively, the prepared concrete has an age of more than 1 year, and the recycled aggregate is obtained through the mechanical action of a jaw crusher. Before the recycled aggregate is immersed in isopropanol and absolute ethyl alcohol, as shown in fig. 9, the surface of the recycled aggregate is provided with old mortar, the recycled aggregate is completely immersed in the isopropanol, immersed for 10 days, taken out and naturally dried; soaking in absolute ethanol for 8 days, taking out, and naturally airing; then immersing the mixture into a mixed reagent with the mass ratio of isopropanol to absolute ethyl alcohol of 1:1, immersing for 6 days, taking out and naturally airing, taking the mixture as one period, periodically repeating the process, circulating for 18 periods, observing the surface of the recycled aggregate again, and finding that the old mortar naturally falls off to obtain the recycled aggregate after the weak mortar is removed, as shown in fig. 10.
While the foregoing description of the embodiments of the present invention has been presented in conjunction with the drawings, it should be understood that it is not intended to limit the scope of the invention, but rather, it is intended to cover all modifications or variations within the scope of the invention as defined by the claims of the present invention.
Claims (7)
1. The method for removing the weak layer of the recycled aggregate old mortar is characterized by comprising the following steps of:
crushing the concrete to obtain recycled aggregate;
putting the recycled aggregate into isopropanol solution for soaking and saturation, and then taking out to obtain the initial recycled aggregate, wherein the method specifically comprises the following steps: completely immersing the recycled aggregate in isopropanol solution, immersing for 6-10 days, taking out and naturally airing to obtain initial recycled aggregate;
the initial recycled aggregate is put into absolute ethanol solution for soaking saturation and then is taken out, and the intermediate recycled aggregate is obtained, which is specifically as follows: immersing the initial recycled aggregate in an absolute ethyl alcohol solution for 5-8 days, taking out and naturally airing to obtain intermediate recycled aggregate;
placing the intermediate recycled aggregate into a mixed fusion solution of isopropanol and absolute ethyl alcohol, soaking and saturating, and then taking out to obtain the treated recycled aggregate, wherein the method specifically comprises the following steps: immersing the intermediate recycled aggregate in a mixed solution of isopropanol and absolute ethyl alcohol in a mass ratio of 1:1 for 4-7 days, taking out and naturally airing to obtain the treated recycled aggregate;
the three soaking processes are taken as one period, the periodic repeated soaking is carried out, the cyclic treatment is carried out in a certain period, so that the dense aggregate pores can not generate volume deformation, ettringite in the cement phase of the old mortar loses crystal water, the volume is reduced, and the deformation of the aggregate and the old mortar is not coordinated; the interface between the old mortar and the recycled aggregate is deformed and cracked to obtain the recycled aggregate with cracks;
and sieving the recycled aggregate with the cracks to obtain the aggregate with weak mortar removed, and realizing the effective removal of the recycled aggregate old mortar.
2. The method for removing the old mortar weak layer of recycled aggregate according to claim 1, wherein the concrete preparation process comprises the following steps:
mixing and stirring cement, water, fine aggregate, coarse aggregate and minerals for 3-5 min, adding the chemical additive into the mixture three times in equal amount, and stirring for 6-10 min in the whole course to obtain the concrete for preparing the recycled aggregate.
3. The method for removing the old mortar weak layer of recycled aggregate according to claim 2, wherein the chemical additive is an expanding agent, and the mass fraction of CaO and CSA components is 20-35% and 35-45%.
4. The method for removing the old mortar weak layer of recycled aggregate according to claim 1, wherein for the periodic repeated soaking, the longer the age of the concrete is, the longer the cycle period is.
5. The method for removing the old mortar weak layer of recycled aggregate according to claim 1, wherein as the cycle period increases, old mortar ettringite in the recycled aggregate is dehydrated to deform the aggregate and the old mortar, the recycled aggregate and the old mortar interface generate stress, and cracks appear on the surface of the recycled aggregate under the action of the stress and become larger and larger, so that the old mortar naturally falls off from the surface of the aggregate.
6. The method for removing the old mortar weak layer from recycled aggregate according to claim 1, wherein the recycled aggregate comprises coarse aggregate and old mortar.
7. The method for removing the old mortar weak layer of recycled aggregate according to claim 1, wherein the recycled aggregate is obtained by crushing concrete by a jaw crusher.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310660699.3A CN116693225B (en) | 2023-06-02 | 2023-06-02 | Method for removing weak layers of recycled aggregate old mortar |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310660699.3A CN116693225B (en) | 2023-06-02 | 2023-06-02 | Method for removing weak layers of recycled aggregate old mortar |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN116693225A CN116693225A (en) | 2023-09-05 |
| CN116693225B true CN116693225B (en) | 2024-04-02 |
Family
ID=87840433
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310660699.3A Active CN116693225B (en) | 2023-06-02 | 2023-06-02 | Method for removing weak layers of recycled aggregate old mortar |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116693225B (en) |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005008460A (en) * | 2003-06-17 | 2005-01-13 | Taiheiyo Material Kk | Mortar concrete |
| CN108675662A (en) * | 2018-06-04 | 2018-10-19 | 安徽理工大学 | A kind of recycled aggregate Frozen-thawed cycled preprocess method |
| CN110482935A (en) * | 2019-09-18 | 2019-11-22 | 哈尔滨工业大学 | The preparation of a kind of cement base repair materials of recoverable and to the undamaged method for dismounting of former xoncrete structure |
| CN110482962A (en) * | 2019-09-18 | 2019-11-22 | 哈尔滨工业大学 | A kind of cement-based material, preparation and its method for dismounting that readily removable can be removed and reuse |
| CN112341055A (en) * | 2020-11-12 | 2021-02-09 | 哈尔滨工业大学 | Method for recycling steel fibers in steel fiber reinforced concrete |
| CN113354369A (en) * | 2021-07-23 | 2021-09-07 | 成都志达商品混凝土厂 | High-strength recycled concrete and preparation method thereof |
| EP4124609A1 (en) * | 2021-07-29 | 2023-02-01 | HeidelbergCement AG | Separation of hardened concrete paste from aggregate |
-
2023
- 2023-06-02 CN CN202310660699.3A patent/CN116693225B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005008460A (en) * | 2003-06-17 | 2005-01-13 | Taiheiyo Material Kk | Mortar concrete |
| CN108675662A (en) * | 2018-06-04 | 2018-10-19 | 安徽理工大学 | A kind of recycled aggregate Frozen-thawed cycled preprocess method |
| CN110482935A (en) * | 2019-09-18 | 2019-11-22 | 哈尔滨工业大学 | The preparation of a kind of cement base repair materials of recoverable and to the undamaged method for dismounting of former xoncrete structure |
| CN110482962A (en) * | 2019-09-18 | 2019-11-22 | 哈尔滨工业大学 | A kind of cement-based material, preparation and its method for dismounting that readily removable can be removed and reuse |
| CN112341055A (en) * | 2020-11-12 | 2021-02-09 | 哈尔滨工业大学 | Method for recycling steel fibers in steel fiber reinforced concrete |
| CN113354369A (en) * | 2021-07-23 | 2021-09-07 | 成都志达商品混凝土厂 | High-strength recycled concrete and preparation method thereof |
| EP4124609A1 (en) * | 2021-07-29 | 2023-02-01 | HeidelbergCement AG | Separation of hardened concrete paste from aggregate |
Also Published As
| Publication number | Publication date |
|---|---|
| CN116693225A (en) | 2023-09-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108793876B (en) | Pervious concrete with waste concrete as aggregate, preparation method and application thereof | |
| Abd Elhakam et al. | Influence of self-healing, mixing method and adding silica fume on mechanical properties of recycled aggregates concrete | |
| Ismail et al. | Engineering properties of treated recycled concrete aggregate (RCA) for structural applications | |
| CN110357472B (en) | Process for preparing recycled coarse aggregate from construction waste | |
| CN110845184A (en) | Recycled aggregate concrete and preparation method thereof | |
| CN109516707B (en) | Preparation method of recycled aggregate for inhibiting alkali-aggregate reaction | |
| CN106830777A (en) | Regeneration fill concrete and its application prepared by consumer waste incineration residue | |
| CN112062533A (en) | Alkali-activated regenerated micro-powder foam concrete and preparation method thereof | |
| CN111393057B (en) | Regeneration method of waste concrete and modified regenerated concrete | |
| CN107777981A (en) | A kind of regeneration concrete and preparation method thereof | |
| CN109265038A (en) | A kind of modification regeneration coarse aggregate and its method for preparing regeneration concrete | |
| CN108191281B (en) | Recycled aggregate concrete interface transition zone strengthening method | |
| Belouadah et al. | Experimental characterization of ordinary concretes obtained by adding construction waste (glass, marble) | |
| Singh et al. | Sustainable use of different size fractions of municipal solid waste incinerator bottom ash and recycled fine aggregates in cement mortar | |
| CN112939551A (en) | Method for preparing recycled concrete by using construction waste | |
| CN107759156B (en) | Concrete formula, preparation method and concrete regeneration process thereof | |
| Tanash et al. | Potential of recycled powder from clay Brick, sanitary Ware, and concrete waste as a cement substitute for Concrete: An overview | |
| CN112479649A (en) | Granite waste residue powder and silica fume synergistic modified recycled aggregate concrete and preparation method thereof | |
| CN116693225B (en) | Method for removing weak layers of recycled aggregate old mortar | |
| CN114230281A (en) | Recycled concrete capable of reducing porosity and preparation method thereof | |
| CN111943545A (en) | Artificial sand and preparation method thereof | |
| CN112062514B (en) | Method for preparing 3D printing ink from waste 3D printing concrete | |
| AU2020102828A4 (en) | A Novel Method to Determine Enhanced Strength of Recycled Concrete based on Micro Filler Technique | |
| CN114573301A (en) | Preparation method of novel composite cement-based grouting material | |
| Ismail et al. | Effect surface treatment of recycled concrete aggregate on properties of fresh and hardened concrete |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |