CN113896456A - Process for preparing recycled asphalt mixture by using construction waste recycled aggregate - Google Patents
Process for preparing recycled asphalt mixture by using construction waste recycled aggregate Download PDFInfo
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- CN113896456A CN113896456A CN202111264765.2A CN202111264765A CN113896456A CN 113896456 A CN113896456 A CN 113896456A CN 202111264765 A CN202111264765 A CN 202111264765A CN 113896456 A CN113896456 A CN 113896456A
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- 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
- C04B26/00—Compositions of mortars, concrete or artificial stone, containing only organic binders, e.g. polymer or resin concrete
- C04B26/02—Macromolecular compounds
- C04B26/26—Bituminous materials, e.g. tar, pitch
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- 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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00017—Aspects relating to the protection of the environment
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- 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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/0075—Uses not provided for elsewhere in C04B2111/00 for road construction
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- 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
Abstract
The invention discloses a process for preparing a recycled asphalt mixture by using construction waste recycled aggregate, which comprises the following steps: screening the crushed construction waste recycled aggregate into recycled coarse aggregate and recycled fine aggregate; mechanically strengthening the recycled coarse aggregate to obtain the strengthened recycled coarse aggregate, wherein the mechanical strengthening comprises removing cement mortar coated on the surface of the recycled coarse aggregate and polishing off edges and corners on the surface of the recycled coarse aggregate; introducing CO into the recycled fine aggregate2Chemically strengthening the gas to obtain strengthened recycled fine aggregate; and respectively doping a certain amount of reinforced recycled coarse aggregate and reinforced recycled fine aggregate into corresponding natural coarse aggregate and natural fine aggregate, and designing the mixing proportion of the recycled asphalt mixture to prepare the recycled asphalt mixture. The invention can fully utilize a large amount of construction waste resources generated in life, produce good recycled aggregate and mix the good recycled aggregate into the asphalt mixture to prepare the recycled asphalt mixture, and realize the aims of circular development and green development of highway construction.
Description
Technical Field
The invention belongs to the field of road engineering, and particularly relates to a process for preparing a recycled asphalt mixture by using construction waste recycled aggregate.
Background
The construction waste refers to residue, waste soil, waste material, sludge and other wastes generated in the process of constructing, laying or dismantling and repairing various buildings, structures, pipe networks and the like by construction and construction units or individuals. At present, the urbanization construction is fast, so that a very large amount of construction wastes are generated, and how to treat the construction wastes becomes an urgent affair. By 2020, the area of the newly added building is about 300 hundred million m2The production amount of the construction waste reaches 50 hundred million t. However, the total resource utilization rate of the construction waste is less than 10%, and the method has a large gap compared with the utilization rate of 90% in some countries in Europe and America and the utilization rate of 95% in Japan and Korean, and the treatment method is still simple in landfill and stacking.
On the other hand, the number of road infrastructure projects is continuously increased, a large amount of natural aggregate is needed, high-grade roads are mainly asphalt pavements, and the content of coarse aggregate and fine aggregate in the asphalt mixture is more than 90%. If the construction waste is reformed into usable aggregate in roads, the use of natural aggregate can be greatly reduced, and the cost is saved; meanwhile, the waste construction waste is recycled, and the utilization rate of resources is greatly improved.
The construction waste is used as a renewable resource to realize the utilization of the waste construction waste, so that the method is an effective method, the problem of the ubiquitous storage of the construction waste is solved, the construction waste can be reused in roads, and the green development and cyclic development modes are realized. At present, research mainly focuses on doping construction waste recycled aggregate into prepared cement concrete, is limited to the construction waste recycled coarse aggregate in the research of doping few recycled aggregates into asphalt mixture for building pavements, does not fully utilize the construction waste recycled fine aggregate, and often cannot be fully combined with the performance of the recycled aggregate to strengthen the performance of the recycled asphalt mixture in the research process. The problems that the construction waste resources can not be fully utilized, the performance of the recycled asphalt mixture can not reach the optimum and the like are caused.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a process for preparing a recycled asphalt mixture by using construction waste recycled aggregate, which can fully utilize a large amount of construction waste resources generated in life, produce good recycled aggregate and mix the good recycled aggregate into the asphalt mixture to prepare the recycled asphalt mixture, and realize the aims of circular development and green development of highway construction.
In order to solve the technical problems, the invention is realized by the following technical scheme:
a process for preparing a recycled asphalt mixture by using construction waste recycled aggregates comprises the following steps:
screening the crushed construction waste recycled aggregate into recycled coarse aggregate and recycled fine aggregate;
mechanically strengthening the recycled coarse aggregate to obtain a strengthened recycled coarse aggregate, wherein the mechanical strengthening comprises removing cement mortar coated on the surface of the recycled coarse aggregate and polishing off edges and corners on the surface of the recycled coarse aggregate;
introducing CO into the recycled fine aggregate2Chemically strengthening the gas to obtain strengthened recycled fine aggregate;
and respectively doping the reinforced recycled coarse aggregate and the reinforced recycled fine aggregate into the corresponding natural coarse aggregate and natural fine aggregate, and then designing the mixing ratio of the recycled asphalt mixture to prepare the recycled asphalt mixture.
Further, introducing CO into the recycled fine aggregate2The gas is chemically strengthened to obtain the strengthened recycled fine aggregate, which specifically comprises the following steps:
putting the recycled fine aggregate into a closed container, and adding CO2Gas concentration of 80-100% and CO2Keeping the gas pressure at 0.3-0.5MPa for a certain time.
Further, when the reinforced recycled coarse aggregate is doped into the corresponding natural coarse aggregate, the doping amount is not more than 30%; when the reinforced recycled fine aggregate is doped into the corresponding natural fine aggregate, the doping amount is not more than 30%.
Further, after the reinforced recycled coarse aggregate is obtained and before the design of the mix proportion, whether the crushing value, the los angeles abrasion value, the water absorption and the needle flake content index of the reinforced recycled coarse aggregate meet preset requirements or not is tested, and if the crushing value, the los angeles abrasion value, the water absorption and the needle flake content index do not meet the preset requirements, mechanical reinforcement is continuously carried out until the requirements are met.
Further, after obtaining the reinforced recycled fine aggregate and before designing the mixing proportion, testing whether the mud content and firmness indexes of the reinforced recycled fine aggregate meet preset requirements, and if not, continuing chemical reinforcement until the requirements are met.
Further, before the recycled fine aggregate is obtained and chemically strengthened, the method also comprises the step of removing ash from the recycled fine aggregate by a water washing method to remove soluble impurities.
Further, the recycled fine aggregate is subjected to ash removal by a water washing method, and after soluble impurities are removed, the content of silt impurities in the recycled fine aggregate is less than 1%.
Further, the design of the mixing proportion of the recycled asphalt mixture is carried out, and after the recycled asphalt mixture is prepared, a performance test is carried out on the prepared recycled asphalt mixture.
Further, the performance tests include a wheel rut test, a water immersion marshall test, and a trabecular bending test.
Compared with the prior art, the invention has at least the following beneficial effects: the invention provides a process for preparing a recycled asphalt mixture by using construction waste recycled aggregate, which not only realizes the purpose of fully utilizing waste construction waste resources, but also solves the problem of the shortage of natural aggregate of the road at present to a certain extent, and embodies the concepts of green development and cyclic development. In the previous research, the recycled coarse aggregate obtained after the construction waste is crushed is often directly mixed into the recycled mixture, the surface of the recycled coarse aggregate is often higher in crushing value index and low in strength due to the fact that a large amount of cement mortar substances with loose texture are attached to the surface of the recycled coarse aggregate, and meanwhile, recycled coarse aggregate particles obtained after crushing often have more sharp edges and corners, and the embedded and extruded framework formed inside the recycled coarse aggregate particles after being mixed into the recycled mixture has adverse effects. In order to eliminate the adverse effect of the recycled coarse aggregate, the process of the invention adopts a mechanical strengthening technical method, removes cement mortar with lower particle surface strength by utilizing the high-speed rotation collision of the recycled coarse aggregate among particles in a closed machine, and simultaneously leads the edges and corners of the particles to become rounded under the collision action, thereby obtaining the recycled coarse aggregate with obviously improved performance compared with the prior art. Meanwhile, in the prior art research, recycled coarse aggregate is often used in the recycled aggregate of the building rubbish, and the recycled fine aggregate generated at the same time is generally ignored due to the disadvantage of performance, so that the waste of the part of resources is caused. The recycled fine aggregate has small apparent density, high water absorption and low strength, and the main reasons for the reasons are that the recycled fine aggregate is rich in a plurality of cement mortar particles generated in the crushing process due to small particle volume2The performance of the recycled fine aggregate is enhanced by the carbonization reaction principle of the gas and the recycled fine aggregate. CO 22Technical source for reinforcing recycled fine aggregateThe reason is as follows:
Ca(OH)2﹢CO2→CaCO3﹢H2O
C-S-H﹢CO2→CaCO3﹢SiO2·H2O
the components of the cement mortar in the recycled fine aggregate of the construction waste are mainly calcium hydroxide, water-based calcium silicate and CO2After the gas contacts, carbonization reaction can occur, and the products are calcium carbonate and silica gel. The volume of the solid phase body is increased before and after the reaction, the compactness of the cement mortar is increased, and the integral porosity is reduced, so that the water absorption of the recycled fine aggregate is reduced, and the density and the strength of the aggregate are increased. The method is simple and economical and can be used by only putting the recycled fine aggregate into a closed container and then introducing CO2The reaction is carried out quickly, and the strengthening can be completed only by fully reacting the gas and the liquid for 1-2 hours. In addition, soluble impurities such as silt and the like contained in the recycled fine aggregate are cleaned by a water washing method in the process, so that the adverse effect of the impurities on the recycled asphalt mixture is avoided. After the recycled coarse and fine aggregates with good performance are obtained, the type of the recycled asphalt mixture can be determined according to actual needs, then the mix proportion design under different recycled aggregate mixing amounts is carried out, and then the performance of the recycled asphalt mixture under each recycled aggregate mixing amount is tested.
In summary, the following steps: the invention can fully utilize the waste building waste resources, realizes the purposes of recycling resources and saving resources, and simultaneously strengthens the performance of the recycled coarse and fine aggregates in different modes before being mixed into the recycled asphalt mixture, thereby ensuring that each performance index of the coarse and fine recycled aggregates basically meets the use requirement, further ensuring that the recycled asphalt mixture has good performance after being put into engineering use, and meeting the requirement of actual engineering. The invention saves resources and financial resources, does not sacrifice the quality of the regenerated asphalt mixture, has important positive significance for realizing the aim of 'double carbon' in China, and is worth further exploring in future research and practice.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a process flow chart of preparing a recycled asphalt mixture by using construction waste recycled aggregate according to the invention.
Detailed Description
To make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some, but not all embodiments of the present 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.
The invention relates to a process for preparing a recycled asphalt mixture by using construction waste recycled aggregate, which mainly comprises a construction waste sorting process, a construction waste crushing process, a performance strengthening process of the construction waste recycled aggregate, a mixing proportion design process of the recycled asphalt mixture and a performance inspection process of the recycled asphalt mixture.
The construction waste sorting process refers to the step of preliminarily sorting the construction waste stones recovered from the construction site according to the conditions of the composition, the impurity content and the like, and sorting the available construction waste stones for the next step of crushing.
The construction waste crushing process is to crush the selected construction waste into asphalt mixture with the required particle size.
The performance strengthening process of the construction waste recycled aggregate is to strengthen the engineering properties of the recycled coarse and fine aggregates obtained by crushing in the last step by methods such as physical chemistry and the like, so as to obtain the recycled coarse and fine aggregates which are more suitable for being used in corresponding asphalt mixtures.
The design process of the mixing proportion of the construction waste recycled asphalt mixture refers to the determination of the mixing proportion of construction waste recycled aggregates with different mixing amounts under the type of a target asphalt mixture, and mainly comprises two parts of mineral mixture composition design and determination of the optimal asphalt using amount.
The performance inspection process of the recycled asphalt mixture refers to the inspection of the high-temperature performance, the water stability and the low-temperature performance of the recycled mixture which is subjected to the mix proportion design, and the recycled asphalt mixture can be put into use after the recycled asphalt mixture is qualified.
Specifically, the invention relates to a process for preparing a recycled asphalt mixture by using construction waste recycled aggregate, which specifically comprises the following steps:
the method comprises the following steps: and (5) manually primarily selecting the construction waste.
Specifically, the recycled construction waste is collected in a stock dump, 1-1.5 tons of construction waste is distributed to 1 unit by an excavator, 2-3 workers are allocated to each unit for primary selection of the construction waste, a waste dustbin is provided, materials such as bricks, steel bars, textiles and plastics which have adverse effects on the performance of the recycled asphalt mixture are selected, and the adverse materials are placed in the waste dustbin, so that the content of the materials such as the bricks, the steel bars, the textiles and the plastics is less than 5% of the total amount of the construction waste.
Step two: and (4) putting the construction waste into a bar vibration feeder for primary screening.
The step three is used for coarsely crushing large building garbage, ensuring the uniform feeding in the step three, and simultaneously removing fine materials such as soil and the like, and after the process is finished, the building garbage directly enters a jaw crusher in the step three to be crushed;
in the step, 1-1.5 tons of construction waste are taken as a unit and put into a machine in sequence.
Step three: and the building garbage after primary screening enters a jaw crusher by a bar vibrating feeder to be crushed.
Specifically, the crushing process is two crushing processes, the first crushing process is used for crushing the construction waste with the diameter of 0-30mm, and each unit of construction waste is crushed for 5-10 minutes; and the secondary crushing process is to crush the recycled aggregate with the diameter larger than 30mm in the primary crushing process again, and each unit of construction waste is crushed for 5-10 minutes.
Step four: and screening the crushed construction waste recycled aggregate into recycled coarse aggregate and recycled fine aggregate.
Specifically, a material separator is adopted to divide the crushed construction waste recycled aggregate into coarse recycled aggregate and fine recycled aggregate with the particle diameter of 2.36 mm.
Step five: the obtained recycled coarse aggregate is mechanically reinforced.
Specifically, the mechanical strengthening can utilize the regenerated coarse aggregate to rotate and collide at a high speed under the drive of power in a machine so as to enable cement mortar wrapped on the surfaces of particles to fall off, and meanwhile, the collision among the regenerated coarse aggregates can grind off sharp edges and corners on the surfaces, so that the shape of the regenerated coarse aggregate is improved. In the operation process, firstly, the construction waste recycled coarse aggregate needs to be placed into the feeding hole at a constant speed, the reinforcing aggregate discharging hole below the machine needs to be continuously cleaned in the reinforcing process so as to avoid blockage, and the construction waste placed into the machine each time is about 1 ton approximately. In order to ensure the thoroughness of mechanical reinforcement and avoid the problem that the mechanical reinforcement effect of individual recycled coarse aggregates is not obvious, the mechanical reinforcement process is repeated for 2 to 3 times, and each time lasts for 5 to 10 minutes.
Step six: and (3) removing ash from the obtained recycled fine aggregate by a water washing method, and removing soluble impurities.
Specifically, the recycled fine aggregate is fully soaked and washed for 10-20 minutes, and the content of silt impurities in the washed recycled fine aggregate is less than 1%.
Step seven: chemically strengthening (CO) the washed recycled fine aggregate2Gas reinforcement).
Specifically, the washed recycled fine aggregate is passed through CO2The gas strengthening technical method strengthens the performance of part of cement mortar contained in the recycled fine aggregate. In this step, the recycled fine aggregate should be placed in a closed container in CO2Gas concentration of 80% -100%, CO2Keeping the pressure of the gas at 0.3-0.5MPa for about 1 hour.
Step eight: and (4) further screening the reinforced recycled coarse aggregate and the recycled fine aggregate in detail.
Specifically, the recycled coarse aggregate and the recycled fine aggregate which are subjected to performance enhancement are screened step by step so as to meet the requirement of subsequently mixing the recycled coarse aggregate and the recycled fine aggregate into the recycled asphalt mixture step by step.
Step nine: and carrying out a basic performance test on the reinforced recycled coarse aggregate and the recycled fine aggregate.
Specifically, for the reinforced recycled coarse aggregate, the crushing value, the los angeles abrasion value, the water absorption and the pin sheet content index of the reinforced recycled coarse aggregate are tested; the recycled fine aggregate after the reinforcement was tested for the mud content and the firmness index. If the indexes do not meet the use standard requirements of the corresponding level of the recycled asphalt mixture, the corresponding strengthening steps are repeated until the basic performance of the recycled coarse and fine aggregate can meet the corresponding standard requirements. The aggregate specifications are shown in table 1 below:
TABLE 1 technical Specification requirements for aggregates for asphalt mixtures
Step ten: and respectively doping a certain amount of reinforced recycled coarse aggregate and reinforced recycled fine aggregate into corresponding natural coarse aggregate and natural fine aggregate, and designing the mixing proportion of the recycled asphalt mixture to prepare the recycled asphalt mixture.
Specifically, according to related researches, when the mixing amount of the construction waste recycled aggregate is in the range of 0-30%, the performance of the recycled asphalt mixture is kept good, and the use specification requirements can be basically met. Therefore, in the process, the mixing amount of the recycled aggregate in each grade of aggregate is regulated to be controlled within the range of 0-30 percent. In the engineering embodiment, after a specific recycled aggregate mixing amount is determined, the type of the hot-mix asphalt mixture is determined, and a proper grading curve is selected to complete the mineral aggregate synthesis grading determination. And then determining the aggregate dosage of each particle size in an asphalt Marshall test according to the designed mixing amount of the construction waste recycled aggregate, then performing the asphalt Marshall test, and determining the optimal asphalt dosage under the mixing amount of the construction waste recycled aggregate according to the maximum gross volume density, the maximum stability, the target void ratio (or the median value of the void ratio range), the asphalt dosage corresponding to the median value of the asphalt saturation and the maximum and minimum asphalt dosages of each index of the mixture meeting the standard requirements, so as to complete the mix proportion design of the recycled asphalt mixture.
Step eleven: and (5) carrying out performance inspection on the recycled asphalt mixture.
Specifically, performance tests are carried out on the recycled asphalt mixture under different mixing amounts of the construction waste recycled aggregate, the recycled asphalt mixture needs to be controlled under the optimal asphalt dosage determined in the step ten, the performance tests mainly comprise a wheel tracking test (high-temperature stability), a soaking Marshall test (water stability) and a trabecular bending test (low-temperature performance), if the obtained dynamic stability, soaking residual stability and low-temperature failure strain indexes can respectively meet the requirements of the following tables 2, 3 and 4, the recycled asphalt mixture under the mixing amount of the construction waste recycled aggregate can meet the requirements of actual engineering, and otherwise, the use requirements cannot be met.
TABLE 2 technical requirements for dynamic stability of rut test of asphalt mixture
TABLE 3 Water stability test technical requirements for asphalt mixtures
TABLE 4 technical requirement for low-temperature failure strain (mu epsilon) of asphalt mixture
The construction waste recovered from construction sites has mixed components and contains a plurality of impurities which are not suitable for being used in the regeneration process, and the substances are preliminarily removed by a manual platform separation method, so that the adverse effect on the subsequent process is avoided. The construction waste is only roughly selected by a manual method, only the adverse components with larger volume can be removed, and the fine particles such as silt can be removed by the bar-type vibrating feeder before the construction waste is crushed. Through the steps, impurities contained on the surface of the construction waste before crushing and having adverse effects on the performance of the asphalt mixture can be reduced to the minimum, and efficient separation of the construction waste is realized.
Example 1
The process for preparing the recycled asphalt mixture by using the construction waste recycled aggregate can be used in engineering practice and realizes efficient recycling of resources. In the embodiment 1 of the invention, the construction waste recycled aggregate is mixed into the recycled asphalt mixture AC-16 with the mixing amount of 10% per grade, and the mixture is used for the surface layer of the asphalt pavement. The method specifically comprises the following steps:
the method comprises the following steps: and (5) manually primarily selecting the construction waste.
Collecting the recycled construction waste in a stock ground, adopting an excavator to take 1-1.5 tons as 1 unit, distributing 2-3 workers to each unit for primary selection of the construction waste, preparing a waste dustbin, selecting bricks, reinforcing steel bars, textiles, plastics and other substances which have adverse effects on the performance of the recycled asphalt mixture, and placing the adverse substances in the waste dustbin to ensure that the content of the bricks, the reinforcing steel bars, the textiles, the plastics and other substances is less than 5 percent of the total amount of the construction waste.
Step two: and (4) putting the construction waste into a bar vibration feeder for primary screening.
In the step, 1-1.5 tons of construction waste are taken as a unit and put into a machine in sequence.
Step three: and the construction waste enters a jaw crusher to be crushed.
The construction waste is primarily screened by the bar-shaped vibrating feeder in the second step and then directly enters a jaw crusher, the crushing process is a twice crushing process, the first crushing process is used for crushing recycled aggregates with the diameter of 0-30mm, and each unit of construction waste is crushed for 5 minutes; and in the second crushing process, the recycled aggregate with the diameter larger than 30mm in the first crushing process is crushed again, and each group of construction waste is crushed for 5 minutes.
Step four: and screening the crushed construction waste recycled aggregate into recycled coarse aggregate and recycled fine aggregate.
And dividing the crushed construction waste recycled aggregate into coarse recycled aggregate and fine recycled aggregate by a material separator according to the particle diameter of 2.36 mm.
Step five: the obtained recycled coarse aggregate is mechanically reinforced.
The construction waste put into the machine is about 1 ton each time, and the mechanical strengthening process should be repeated for 2 times, and 5 minutes each time.
Step six: and (3) removing ash from the obtained recycled fine aggregate by a water washing method, and removing soluble impurities.
The recycled fine aggregate is added into sufficient water to ensure that the recycled fine aggregate can be fully soaked and washed, the soaking and washing time is about 10 minutes, and the content of silt impurities in the washed fine aggregate is less than 1%.
Step seven: chemically strengthening (CO) the washed recycled fine aggregate2Gas reinforcement).
The washed recycled fine aggregate is passed through CO2The gas strengthening technical method strengthens the performance of part of cement mortar contained in the recycled fine aggregate. In this step, the recycled fine aggregate should be placed in a closed container in CO2Gas concentration of 80% -100%, CO2Keeping the gas pressure at 0.3-0.5MPa for 1 hour.
Step eight: the reinforced coarse and fine recycled aggregates are further screened in detail.
And step-by-step screening the coarse and fine recycled aggregates after the performance enhancement in the step six and the step seven.
Step nine: the reinforced recycled aggregate was subjected to a basic performance test.
For the reinforced recycled coarse aggregate, the crushing value, the los Angeles abrasion value, the water absorption and the pin sheet content index are tested; the recycled fine aggregate after the reinforcement was tested for the mud content and the firmness index. The indexes are in accordance with the technical requirements of the aggregate for the road of the road asphalt mixture of the target grade, the specific standard requirement values are shown in table 1 in the specification, and if the indexes are not in accordance with the standard, the corresponding strengthening steps are repeated until the basic performance of the recycled aggregate can meet the requirements of the corresponding standard.
Step ten: and respectively doping a certain amount of reinforced recycled coarse aggregate and reinforced recycled fine aggregate into the corresponding natural coarse aggregate and natural fine aggregate, and then designing the mixing ratio of the recycled asphalt mixture.
In the embodiment, the mixing amount of the construction waste recycled aggregate is 10%, the use amount proportion of the recycled aggregate and the natural aggregate in each grade is determined according to a synthetic grading curve of the AC-16 type asphalt mixture, then an asphalt Marshall test is carried out, and the optimal asphalt use amount under the mixing amount of the construction waste recycled aggregate is determined according to the maximum gross volume density, the maximum stability, the target void ratio (or the median value in the void ratio range), the corresponding asphalt use amount at the median value of the asphalt saturation and the maximum and minimum asphalt use amounts of each index of the mixture meeting the standard requirements, so that the mix proportion design of the recycled asphalt mixture is completed.
Step eleven: and (5) inspecting the performance of the recycled asphalt mixture.
The performance tests of the recycled asphalt mixture under different mixing amounts of the recycled aggregate of the construction waste are carried out, the recycled asphalt mixture needs to be controlled under the optimal asphalt dosage determined in the step ten, the performance tests mainly comprise a wheel tracking test (high-temperature stability), a soaking Marshall test (water stability) and a trabecular bending test (low-temperature performance), and if the obtained dynamic stability, soaking residual stability and low-temperature failure strain indexes can respectively meet the requirements of tables 2, 3 and 4 in the specification, the recycled asphalt mixture under the mixing amount of the recycled aggregate of the construction waste can meet the requirements of actual engineering; otherwise, the use requirement cannot be met, and the mixing amount of the building waste recycled aggregate is correspondingly reduced during use.
Example 2
In the embodiment 2 of the invention, the construction waste recycled aggregate is mixed into the recycled asphalt mixture AC-16 with the mixing amount of 20% per grade and is used for the surface layer of the asphalt pavement. The method specifically comprises the following steps:
the method comprises the following steps: and (5) manually primarily selecting the construction waste.
Collecting the recycled construction waste in a stock ground, adopting an excavator to take 1-1.5 tons as 1 unit, distributing 2-3 workers to each unit for primary selection of the construction waste, preparing a waste dustbin, selecting bricks, reinforcing steel bars, textiles, plastics and other substances which have adverse effects on the performance of the recycled asphalt mixture, and placing the adverse substances in the waste dustbin to ensure that the content of the bricks, the reinforcing steel bars, the textiles, the plastics and other substances is less than 5 percent of the total amount of the construction waste.
Step two: and (4) putting the construction waste into a bar vibration feeder for primary screening.
In the step, 1-1.5 tons of construction waste are taken as a unit and put into a machine in sequence.
Step three: and the construction waste enters a jaw crusher to be crushed.
The construction waste is primarily screened by the bar-shaped vibrating feeder in the second step and then directly enters a jaw crusher, the crushing process is a twice crushing process, the first crushing process is used for crushing recycled aggregates with the diameter of 0-30mm, and each unit of construction waste is crushed for 5 minutes; and in the second crushing process, the recycled aggregate with the diameter larger than 30mm in the first crushing process is crushed again, and each group of construction waste is crushed for 5 minutes.
Step four: and screening the crushed construction waste recycled aggregate into recycled coarse aggregate and recycled fine aggregate.
And dividing the crushed construction waste recycled aggregate into coarse recycled aggregate and fine recycled aggregate by a material separator according to the particle diameter of 2.36 mm.
Step five: the obtained recycled coarse aggregate is mechanically reinforced.
The construction waste put into the machine is about 1 ton each time, and the mechanical strengthening process should be repeated for 2 times, and 7 minutes each time.
Step six: and (3) removing ash from the obtained recycled fine aggregate by a water washing method, and removing soluble impurities.
The recycled fine aggregate is added into sufficient water to ensure that the recycled fine aggregate can be fully washed, the washing time is about 12 minutes, and the content of silt impurities in the washed recycled fine aggregate is less than 1%.
Step seven: chemically strengthening (CO) the washed recycled fine aggregate2Gas reinforcement).
The washed recycled fine aggregate is passed through CO2The gas strengthening technical method strengthens the performance of part of cement mortar contained in the recycled fine aggregate. In this step, the recycled fine aggregate should be placed in a closed container in CO2Gas concentration of 80% -100%, CO2Keeping the pressure of the gas at 0.3-0.5MPa for about 1 hour.
Step eight: the reinforced coarse and fine recycled aggregates are further screened in detail.
And step-by-step screening the coarse and fine recycled aggregates after the performance enhancement in the step six and the step seven.
Step nine: the reinforced recycled aggregate was subjected to a basic performance test.
For the reinforced recycled coarse aggregate, the crushing value, the los Angeles abrasion value, the water absorption and the pin sheet content index are tested; the recycled fine aggregate after the reinforcement was tested for the mud content and the firmness index. The indexes are in accordance with the technical requirements of the aggregate for the asphalt mixture road on the surface layer, the specific numerical values are shown in table 1 in the specification, and if the indexes are not in accordance with the specification, the corresponding strengthening steps are repeated until the basic performance of the recycled aggregate can meet the requirements of the corresponding specification.
Step ten: and respectively doping a certain amount of reinforced recycled coarse aggregate and reinforced recycled fine aggregate into the corresponding natural coarse aggregate and natural fine aggregate, and then designing the mixing ratio of the recycled asphalt mixture.
In the embodiment, the mixing amount of the construction waste recycled aggregate is 20%, the use amount proportion of the recycled aggregate and the natural aggregate in each grade is determined according to a synthetic grading curve of the AC-16 type asphalt mixture, then an asphalt Marshall test is carried out, and the optimal asphalt use amount under the mixing amount of the construction waste recycled aggregate is determined according to the maximum gross volume density, the maximum stability, the target void ratio (or the median value in the void ratio range), the corresponding asphalt use amount at the median value of the asphalt saturation and the maximum and minimum asphalt use amounts of each index of the mixture meeting the standard requirements, so that the mix proportion design of the recycled asphalt mixture is completed.
Step eleven: and (5) inspecting the performance of the recycled asphalt mixture.
The performance tests of the recycled asphalt mixture under different mixing amounts of the recycled aggregate of the construction waste are carried out, the recycled asphalt mixture needs to be controlled under the optimal asphalt dosage determined in the step ten, the performance tests mainly comprise a wheel tracking test (high-temperature stability), a soaking Marshall test (water stability) and a trabecular bending test (low-temperature performance), and if the obtained dynamic stability, soaking residual stability and low-temperature failure strain indexes can respectively meet the requirements of tables 2, 3 and 4 in the specification, the recycled asphalt mixture under the mixing amount of the recycled aggregate of the construction waste can meet the requirements of actual engineering; otherwise, the use requirement cannot be met, and the mixing amount of the building waste recycled aggregate is correspondingly reduced during use.
Example 3
In the embodiment 3 of the invention, the construction waste recycled aggregate is mixed into the recycled asphalt mixture AC-16 with the mixing amount of 30% per grade and is used for the surface layer of the asphalt pavement. The method specifically comprises the following steps:
the method comprises the following steps: and (5) manually primarily selecting the construction waste.
Collecting the recycled construction waste in a stock ground, adopting an excavator to take 1-1.5 tons as 1 unit, distributing 2-3 workers to each unit for primary selection of the construction waste, preparing a waste dustbin, selecting bricks, reinforcing steel bars, textiles, plastics and other substances which have adverse effects on the performance of the recycled asphalt mixture, and placing the adverse substances in the waste dustbin to ensure that the content of the bricks, the reinforcing steel bars, the textiles, the plastics and other substances is less than 5 percent of the total amount of the construction waste.
Step two: and (4) putting the construction waste into a bar vibration feeder for primary screening.
In the step, 1-1.5 tons of construction waste are taken as a unit and put into a machine in sequence.
Step three: and the construction waste enters a jaw crusher to be crushed.
The construction waste is primarily screened by the bar-shaped vibrating feeder in the second step and then directly enters a jaw crusher, the crushing process is a twice crushing process, the first crushing process is used for crushing recycled aggregates with the diameter of 0-30mm, and each unit of construction waste is crushed for 5 minutes; and in the second crushing process, the recycled aggregate with the diameter larger than 30mm in the first crushing process is crushed again, and each group of construction waste is crushed for 5 minutes.
Step four: and screening the crushed construction waste recycled aggregate into recycled coarse aggregate and recycled fine aggregate.
And dividing the crushed construction waste recycled aggregate into coarse recycled aggregate and fine recycled aggregate by a material separator according to the particle diameter of 2.36 mm.
Step five: the obtained recycled coarse aggregate is mechanically reinforced.
The construction waste put into the machine is about 1 ton each time, and the mechanical strengthening process should be repeated for 2 times, 8 minutes each time.
Step six: and (3) removing ash from the obtained recycled fine aggregate by a water washing method, and removing soluble impurities.
The recycled fine aggregate is added into sufficient water to ensure that the recycled fine aggregate can be fully washed, the washing time is about 15 minutes, and the content of silt impurities in the washed recycled fine aggregate is less than 1%.
Step seven: chemically strengthening (CO) the washed recycled fine aggregate2Gas reinforcement).
The washed recycled fine aggregate is passed through CO2The gas strengthening technical method strengthens the performance of part of cement mortar contained in the recycled fine aggregate. In this step, the recycled fine aggregate should be placed in a closed container in CO2Gas concentration of 80% -100%, CO2Keeping the pressure of the gas at 0.3-0.5MPa for about 1 hour.
Step eight: the reinforced coarse and fine recycled aggregates are further screened in detail.
And step-by-step screening the coarse and fine recycled aggregates after the performance enhancement in the step six and the step seven.
Step nine: the reinforced recycled aggregate was subjected to a basic performance test.
For the reinforced recycled coarse aggregate, the crushing value, the los Angeles abrasion value, the water absorption and the pin sheet content index are tested; the recycled fine aggregate after the reinforcement was tested for the mud content and the firmness index. The indexes are in accordance with the technical requirements of the aggregate for the asphalt mixture road in the table 1 in the specification, if the indexes are out of compliance with the specification, the corresponding strengthening steps are repeated until the basic performance of the recycled aggregate can meet the requirements of the corresponding specification.
Step ten: and respectively doping a certain amount of reinforced recycled coarse aggregate and reinforced recycled fine aggregate into the corresponding natural coarse aggregate and natural fine aggregate, and then designing the mixing ratio of the recycled asphalt mixture.
In the embodiment, the mixing amount of the construction waste recycled aggregate is 30%, the use amount proportion of the recycled aggregate and the natural aggregate in each grade is determined according to a synthetic grading curve of the AC-16 type asphalt mixture, then an asphalt Marshall test is carried out, and the optimal asphalt use amount under the mixing amount of the construction waste recycled aggregate is determined according to the maximum gross volume density, the maximum stability, the target void ratio (or the median value in the void ratio range), the corresponding asphalt use amount at the median value of the asphalt saturation and the maximum and minimum asphalt use amounts of each index of the mixture meeting the standard requirements, so that the mix proportion design of the recycled asphalt mixture is completed.
Step eleven: and (5) inspecting the performance of the recycled asphalt mixture.
The performance tests of the recycled asphalt mixture under different mixing amounts of the recycled aggregate of the construction waste are carried out, the recycled asphalt mixture needs to be controlled under the optimal asphalt dosage determined in the step ten, the performance tests mainly comprise a wheel tracking test (high-temperature stability), a soaking Marshall test (water stability) and a trabecular bending test (low-temperature performance), and if the obtained dynamic stability, soaking residual stability and low-temperature failure strain indexes can respectively meet the requirements of tables 2, 3 and 4 in the specification, the recycled asphalt mixture under the mixing amount of the recycled aggregate of the construction waste can meet the requirements of actual engineering; otherwise, the use requirement cannot be met, and the mixing amount of the building waste recycled aggregate is correspondingly reduced during use.
Finally, it should be noted that: the above-mentioned embodiments are only specific embodiments of the present invention, which are used for illustrating the technical solutions of the present invention and not for limiting the same, and the protection scope of the present invention is not limited thereto, although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the embodiments of the present invention, and they should be construed as being included therein. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (9)
1. A process for preparing a recycled asphalt mixture by using construction waste recycled aggregates is characterized by comprising the following steps:
screening the crushed construction waste recycled aggregate into recycled coarse aggregate and recycled fine aggregate;
mechanically strengthening the recycled coarse aggregate to obtain a strengthened recycled coarse aggregate, wherein the mechanical strengthening comprises removing cement mortar coated on the surface of the recycled coarse aggregate and polishing off edges and corners on the surface of the recycled coarse aggregate;
introducing CO into the recycled fine aggregate2Chemically strengthening the gas to obtain strengthened recycled fine aggregate;
and respectively doping the reinforced recycled coarse aggregate and the reinforced recycled fine aggregate into the corresponding natural coarse aggregate and natural fine aggregate, and then designing the mixing ratio of the recycled asphalt mixture to prepare the recycled asphalt mixture.
2. The process for preparing the recycled asphalt mixture from the recycled aggregate of the construction wastes as claimed in claim 1, wherein the introduction of CO into the recycled fine aggregate2The gas is chemically strengthened to obtain the strengthened recycled fine aggregate, which specifically comprises the following steps:
putting the recycled fine aggregate into a closed container, and adding CO2Gas concentration of 80-100% and CO2Keeping the gas pressure at 0.3-0.5MPa for a certain time.
3. The process for preparing the recycled asphalt mixture by using the construction waste recycled aggregate as claimed in claim 1, wherein the blending amount is not more than 30% when the reinforced recycled coarse aggregate is blended into the corresponding natural coarse aggregate; when the reinforced recycled fine aggregate is doped into the corresponding natural fine aggregate, the doping amount is not more than 30%.
4. The process for preparing a recycled asphalt mixture from construction waste recycled aggregates according to claim 1, wherein after the reinforced recycled coarse aggregates are obtained and before the mix proportion design is performed, whether the crushing value, the los angeles abrasion value, the water absorption and the needle flake content index of the reinforced recycled coarse aggregates meet the preset requirements is tested, and if not, the mechanical reinforcement is continuously performed until the requirements are met.
5. The process for preparing recycled asphalt mixture from recycled aggregate of construction waste according to claim 1, wherein after the reinforced recycled fine aggregate is obtained and before the design of the mixing ratio, the process further comprises testing whether the indexes of mud content and firmness of the reinforced recycled fine aggregate meet the preset requirements, and if not, continuing the chemical reinforcement until the requirements are met.
6. The process for preparing the recycled asphalt mixture from the recycled aggregate of the construction wastes as claimed in claim 1, further comprising washing the recycled fine aggregate with water to remove ash and soluble impurities before the chemical strengthening.
7. The process for preparing the recycled asphalt mixture from the recycled aggregate of the construction wastes as claimed in claim 6, wherein the recycled fine aggregate is subjected to deashing by a water washing method, and after soluble impurities are removed, the content of silt impurities in the recycled fine aggregate is less than 1%.
8. The process for preparing the recycled asphalt mixture by using the construction waste recycled aggregate according to claim 1, wherein the design of the mixing ratio of the recycled asphalt mixture is performed, and after the recycled asphalt mixture is prepared, the performance test of the prepared recycled asphalt mixture is further performed.
9. The process for preparing the recycled asphalt mixture by using the construction waste recycled aggregate as claimed in claim 8, wherein the performance tests comprise a wheel tracking test, a water immersion marshall test and a trabecular bending test.
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