CN115925342A - Method for optimizing mix proportion of in-situ broken recycled water stabilization layer of old cement concrete on road surface - Google Patents
Method for optimizing mix proportion of in-situ broken recycled water stabilization layer of old cement concrete on road surface Download PDFInfo
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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
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Abstract
The invention provides a method for optimizing the mix proportion of an in-situ crushed recycled water-stabilized layer of old cement concrete of a pavement. The method comprises the following sequential steps: s1, determining the optimal gradation of the regenerated aggregate and the optimal clearance rate of a crusher; s2, mixing regenerated mixtures according to different water consumption preset for the water absorption of the regenerated aggregates; s3, distributing materials by adopting a distributor, and determining the actual using amount of a compaction sample with the height of 12.0 cm; s4, distributing the regenerated aggregate by using a distributor, and adding cement and water for mixing; carrying out heavy compaction tests with different water contents on the sample by adopting a compaction cylinder with the height of 17.6cm, leveling by using a sand paving method, and calculating and analyzing a curve to obtain the optimal water content and the maximum dry density; and S5, manufacturing a cylindrical test piece according to the optimal water content and the maximum dry density, performing 7d unconfined compressive strength test, and determining the mixing ratio of the reclaimed water stable layer. This technical scheme presses close to job site actual conditions more, can promote stability and the accuracy of the steady layer mix proportion design of regeneration water on the spot, ensures the steady layer construction quality of regeneration water.
Description
Technical Field
The invention relates to the technical field of road engineering, in particular to a method for optimizing the mix proportion of an in-situ crushed recycled cement concrete stable layer of a pavement.
Background
With the continuous improvement of the living standard of people, the driving comfort level of an early cement concrete pavement can not meet the high-quality requirement of travel, most urban roads are transformed into asphalt concrete pavements, and the trend of changing white roads into black roads of ordinary roads such as national main roads, county roads and rural roads is also a trend. For cement pavements with more damages, how to recycle old cement concrete pavement materials more scientifically and more environmentally, and improve the engineering quality and construction efficiency of changing white into black is a hot point of research in the industry in recent years.
The reflection crack is one of the main factors influencing the quality of the white-to-black engineering asphalt overlay, and the cause is that the asphalt surface layer cracks because the stress formed by the base layer is concentrated and transmitted to the overlay under the comprehensive action of temperature and load stress. Therefore, controlling reflective cracking becomes the key to the "white to black" project. The in-situ crushing (crushing) reclaimed water stabilizing layer technology can be used for in-situ crushing the old cement concrete pavement, adding cement and water on site, stirring and rolling to form a new uniform structural layer, converting the original plate stress into point stress and greatly avoiding the formation of reflection cracks. The technology can completely recycle the old cement concrete pavement material and can also reduce the problem of base strength attenuation caused by other cracking and rubblizing technologies; meanwhile, the technology does not need to establish a mixing station and long-distance transportation of materials, reduces energy consumption, and completely conforms to the concepts of ' green roads ' and ' energy conservation and low carbon ' in the compendium of construction of the traffic force nation '.
The accuracy and reliability of the mix proportion design of the regenerated mixture directly relate to the quality of the regenerated water stable layer, and the determination of the optimal water content and the maximum dry density is the key of the mix proportion design of the regenerated water stable layer. Because the in-situ crushing of the regenerated aggregate is to directly obtain the first-grade continuous graded mixed aggregate, and simultaneously has the characteristics of high water absorption rate, high water absorption speed and the like, if the proportion design of the regenerated aggregate is completely carried out by referring to a heavy compaction test method and an unconfined compressive strength test method in Highway engineering inorganic binder stable material test procedure (JTGE 51), the situation that regular and complete convex curves cannot be connected usually occurs, and the obtained optimal water content and the maximum dry density are not accurate enough and not stable enough.
Disclosure of Invention
In view of the above, the invention aims to provide a mix proportion optimization method for an in-situ crushed recycled water stabilization layer of old cement concrete of a pavement, which overcomes some defects existing when a heavy compaction test method and an unconfined compressive strength test method are adopted to design the mix proportion of the in-situ crushed recycled mixture, so that the mix proportion design of the in-situ crushed recycled mixture is closer to the actual situation of a construction site, the stability and the accuracy of the mix proportion design are improved, and the construction quality of the recycled water stabilization layer is ensured.
In order to achieve the purpose, the invention adopts the following technical scheme: the method for optimizing the mix proportion of the in-situ crushed recycled water-stabilized layer of the old cement concrete of the pavement comprises the following steps:
s1: determining the optimal grading of the regenerated aggregate and the optimal clearance rate of the crusher according to the screening test result of the regenerated mixed aggregate obtained by crushing with different clearance rates;
s2: setting cement dosage according to design requirements, and if the cement dosage is not required, setting different cement dosages; mixing the regenerated mixture according to different water consumption preset by the water absorption of the regenerated aggregate;
s3: distributing materials by using a distributor, and trial-striking the regenerated mixture according to a conventional heavy-duty striking method to determine the actual use amount of a struck material with the height of 12.0 cm;
s4: distributing the regenerated aggregate by using a distributor according to the actual consumption of the compaction test material, and adding cement and water for mixing; carrying out heavy compaction tests with different water contents on the sample by adopting a compaction cylinder with the height of 17.6cm, leveling by using a sand paving method, and calculating and analyzing a curve to obtain the optimal water content and the maximum dry density;
s5: and manufacturing a cylindrical test piece according to the optimal water content and the maximum dry density, performing a 7d unconfined compressive strength test, and determining the mixing proportion of the reclaimed water stable layer.
In a preferred embodiment; in S1, the clearance rate is the ratio of the clearance between a counterattack frame and a rotor frame of the crusher to the maximum grain diameter, continuous graded recycled aggregates meeting the standard JTG/TF20-2015 grading and performance requirements can be directly obtained by adjusting the clearance rate of the crusher, and the optimal grading can be selected and determined only by comparing the results of screening tests and performance tests of the recycled mixed aggregates with different clearance rates.
In a preferred embodiment; in S2, different water consumption is preset according to the water absorption, and the water consumption is generally +2% -5% of the synthetic water absorption of the regenerated aggregate.
In a preferred embodiment; the material is divided by the distributor in S3, and the method is that the sieved sample is gradually divided by a quartering method until about 8 times of the actual amount of the sample is taken; dividing the sample into 8 parts by a distributor, wherein each part has the same mass as the actual dosage, drying and cooling the sample, and sealing with a sealing bag for later use.
In a preferred embodiment; in S3, the actual dose of the proof test sample = (m) 1 -m 2 ) /(1 + 0.01w)/(1 + 0.01c), wherein: m is a unit of 1 The total mass of the test tube and the wet test material; m is 2 The quality of the test cylinder; w is the water content of the sample; c is the mixing amount of the stabilizer in the mixture.
In a preferred embodiment; and S4, the mixing method comprises the steps of flatly paving 1 part of the sample on a clean plane, adding cement with a preset dose into the sample, uniformly mixing the sample with a small shovel, uniformly spraying water with the mass which is calculated to obtain the sample to be added on the sample with the cement, and fully mixing the sample to be in a uniform state with the small shovel.
In a preferred embodiment; the compaction cylinder in S4 has the size of 15.2cm of inner diameter and 17.6cm of height,volume 2286cm 3 And each addition in the compaction process is about 1/3 of the actual dosage.
In a preferred embodiment; in the heavy compaction test in the S4, after 3 layers of test materials are compacted, the test materials adhered to the inner wall of the lantern ring are scraped by a scraper, and the lantern ring is twisted and taken down; wiping the joint of the cylinder top and the lantern ring and the outer wall of the test cylinder, removing the bottom plate, taking away the cushion block, and weighing the mass m 1 (ii) a Slowly adding dry sand of 0.3-0.6 mm from the top of the compaction cylinder until the dry sand completely covers the top; the sand is scrAN _ SNed by the top of the cylinder carefully, the joint between the cylinder top and the lantern ring and the outer wall of the test cylinder are wiped clean, and the mass m of the test cylinder is weighed 3 (ii) a Pouring out dry sand at the top of the cylinder, pushing out a sample in the cylinder by using a stripper, removing the part attached with the sand at the top of the compacted sample by using a scraper and a soft brush, crushing the rest part by using a hammer, then loading the crushed rest part into a tray, and putting the tray into an oven which is adjusted to 105-110 ℃ in advance to measure the water content of the sample, wherein the water content is calculated to be 0.1%; wiping the test tube to obtain the mass m 2 。
In a preferred embodiment; the calculation formula in S4 is the calculation of the wet density of the stabilizing material:
ρ w ＝(m 1- m 2 )/[V-(m 3 -m 1 )/ρ s ]
in the formula: rho w Wet density of the stabilizing material (g/cm) 3 )；
m 1 -total mass of cartridge and wet sample (g);
m 2 -mass of cartridge (g);
v- -compacting cylinder volume (cm) 3 )
m 3 -mass (g) of test cylinder, wet test sample and sand;
ρ s -the apparent density of the sand (g/cm) 3 )。
In a preferred embodiment; the material dividing method for manufacturing the cylindrical test piece in the S5 is to divide 16 times of the standard mass of a single test piece into 16 parts of uniform test pieces by a material divider, immediately seal the uniform test pieces by a plastic bag, and randomly select 13 parts of the uniform test pieces to perform an unconfined compressive strength test.
Compared with the prior art, the invention has the following beneficial effects: the method for optimizing the mix proportion design of the in-situ crushed recycled water stabilization layer of the old cement concrete of the pavement can be closer to the actual situation of a construction site, reduce the test amount for obtaining the optimal gradation and shorten the test time; meanwhile, the method greatly reduces human errors in the test, improves the stability and accuracy of the compaction test and the unconfined compressive strength test, better guides construction, improves engineering quality, and plays an active role in popularization of the in-situ crushing reclaimed water stabilization layer technology.
Drawings
FIG. 1 is a process flow of the full-depth rubblization in-situ regeneration water stabilization technique according to the preferred embodiment of the present invention;
FIG. 2 is a graph showing the screening results of 3 regenerated mixed aggregates with a maximum particle size of 80% as the gap ratio according to the preferred embodiment of the present invention;
FIG. 3 is a graph showing the sieving results of 3 regenerated mixed aggregates with a maximum particle size of 90% as the gap ratio according to the preferred embodiment of the present invention;
FIG. 4 is a conventional heavy duty compaction curve for 5.5kg reclaimed mixed aggregate according to a preferred embodiment of the present invention;
FIG. 5 is a compaction curve of 4.2kg of regenerated mixed aggregate according to a preferred embodiment of the present invention;
FIG. 6 is a graph showing the variation of the optimum moisture content of the reclaimed mix for different infiltration times in accordance with a preferred embodiment of the present invention;
FIG. 7 is a graph of the compaction results of the optimized heavy compaction test method according to the preferred embodiment of the present invention.
Detailed Description
The invention is further explained below with reference to the drawings and the embodiments.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. 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 application 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 application; as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The method for optimizing the mix proportion of the in-situ crushed recycled water-stabilized layer of the old cement concrete of the pavement comprises the following steps:
s1: determining the optimal grading of the regenerated aggregate and the optimal clearance rate of the crusher according to the screening test result of the regenerated mixed aggregate obtained by crushing with different clearance rates;
s2: setting cement dosage according to design requirements, and if the cement dosage is not required, setting different cement dosages; mixing a regenerated mixture according to different water consumption preset by the water absorption of the regenerated aggregate;
s3: distributing materials by using a distributor, and trial-striking the regenerated mixture according to a conventional heavy-duty striking method to determine the actual use amount of a struck material with the height of 12.0 cm;
s4: distributing the regenerated aggregate by using a distributor according to the actual using amount of the compaction sample, and adding cement and water for mixing; carrying out heavy compaction tests with different water contents on the sample by adopting a compaction cylinder with the height of 17.6cm, leveling by using a sand paving method, and calculating and analyzing a curve to obtain the optimal water content and the maximum dry density;
s5: and manufacturing a cylindrical test piece according to the optimal water content and the maximum dry density, performing a 7d unconfined compressive strength test, and determining the mixing proportion of the reclaimed water stable layer.
In S1, the clearance rate is the ratio of the clearance between a counterattack frame and a rotor frame of the crusher to the maximum grain diameter, continuous graded recycled aggregates meeting the standard JTG/T F20-2015 grading and performance requirements can be directly obtained by adjusting the clearance rate of the crusher, and the optimal grading can be selected and determined only by comparing the screening test results and the performance test results of the recycled mixed aggregates with different clearance rates. In S1, the screening test of the regenerated mixed aggregate is a washing method, the regenerated aggregate contains more cement mortar, and the screening result of the washing method is more accurate. In S1, the engineering empirical value of the clearance rate is 70-90% of the maximum grain diameter; the preferable clearance rate range reduces the test workload and shortens the test time.
The water consumption in S2 is different according to the preset water absorption rate and is generally +2% -5% of the synthetic water absorption rate of the regenerated aggregate. In S2, the preset different water consumption is generally +2% -5% of the synthetic water absorption of the regenerated aggregate; the optimal water consumption range can obtain a compaction curve more regularly, and the test result is more accurate.
The material is divided by the material divider in S3, the method is that the sieved sample is gradually divided by a quartering method until about 8 times of the actual dosage of the sample is finally taken; dividing the sample into 8 parts by a distributor, wherein each part has the same mass as the actual dosage, drying and cooling the sample, and sealing with a sealing bag for later use.
In S3, the actual dose of the tapped sample = (m) 1 -m 2 ) /(1 + 0.01w)/(1 + 0.01c), wherein: m is 1 The total mass of the test cylinder and the wet test material; m is a unit of 2 The quality of the test cylinder; w is the water content of the sample; c is the mixing amount of the stabilizer in the mixture. The conventional heavy duty compaction test parameters are referenced to T0804 in JTG E51. In S3, the size of the compacting cylinder used for the compacted sample of 12.0cm height was 15.2cm in inner diameter, 17.0cm in height and 2177cm in volume 3 And the height of the cushion block is 5.0cm. In S3, the actual dosage of the compaction sample is determined according to the average value of the results of conventional heavy compaction tests, and the calculation result is accurate to 10 in whole.
And S4, the mixing method comprises the steps of flatly paving 1 part of the sample on a clean plane, adding cement with a preset dose into the sample, uniformly mixing the sample with a small shovel, uniformly spraying water with the mass which is calculated to obtain the sample to be added on the sample with the cement, and fully mixing the sample to be in a uniform state with the small shovel.
S4, the compaction cylinder has the size of 15.2cm of inner diameter, 17.6cm of height and 2286cm of volume 3 And each charging in the compaction process is about 1/3 of the actual dosage.
In the heavy compaction test in the S4, after 3 layers of test materials are compacted, scraping the test materials adhered to the inner wall of the lantern ring by using a scraper, twisting and taking down the lantern ring; joining the top of the can to the collarCleaning the outer wall of the test tube, removing the bottom plate, taking away the cushion block, and weighing the mass m 1 (ii) a Slowly adding dry sand with the thickness of 0.3-0.6 mm from the top of the compaction cylinder until the dry sand completely covers the top; scraping the sand with the top of the cylinder carefully, wiping off the joint between the cylinder top and the lantern ring and the outer wall of the test cylinder, and weighing the mass m 3 (ii) a Pouring out dry sand at the top of the cylinder, pushing out a sample in the cylinder by using a stripper, scraping off the part attached with the sand at the top of the compaction test piece by using a scraper, crushing the rest part by using a hammer, then loading into a tray, and putting into an oven which is adjusted to 105-110 ℃ in advance to measure the water content of the test piece, wherein the water content is calculated to be 0.1%; wiping the test tube to obtain the mass m 2 。
The calculation formula in S4 is the calculation of the wet density of the stabilizing material:
ρ w ＝(m 1- m 2 )/[V-(m 3 -m 1 )/ρ s ]
in the formula: rho w Wet density of the stabilizing material (g/cm) 3 )；
m 1 -total mass of cartridge and wet sample (g);
m 2 -mass of cartridge (g);
v- -compacting cylinder volume (cm) 3 )
m 3 -mass (g) of test cylinder, wet test sample and sand;
ρ s -the cubic density (g/cm) of the sand 3 )。
The material distributor is adopted to distribute 8 parts of the test materials, the preferable material distribution method is more scientific and convenient, the human error is reduced, each part of the test materials is more uniform, and the stability and the accuracy of the test result are ensured.
In S4, the compacting cylinder with the height of 17.6cm is adopted to compact the recycled mixture with the actual consumption (height of 12.0 cm) of the compacted sample, and the optimized compacting method ensures that the compacted sample meets the compacting height requirement and does not exceed the cylinder top, thereby avoiding the test error caused by the fact that the large aggregate is just positioned at the cylinder top and ensuring the accuracy of the test result.
In S4, after the 3 layers of compaction are finished, the heavy compaction test method adopts dry sand to cover and strickle the residual space at the top of the cylinder, and the preferred operation method reduces human errors and ensures the stability and accuracy of test results.
In S4, ρ S is calculated by referring to step 3.1.4 of T0921 in specification JTG 3450-2019.
The material dividing method for manufacturing the cylindrical test piece in the S5 is characterized in that 16 times of standard mass of a single test piece is divided into 16 parts of uniform test pieces by a material divider, the uniform test pieces are immediately sealed by a plastic bag, and 13 parts of the uniform test pieces are randomly selected for carrying out an unconfined compressive strength test. The material distributing method for manufacturing the cylindrical test piece divides the test material into 16 parts by adopting the material distributor, and the material distributing method is optimized, so that the material distributing method is more scientific and convenient, the human error is reduced, each test material is more uniform, and the stability and the accuracy of the test result are ensured.
In the specific implementation mode of the invention, the adopted old cement concrete on-site crushing and regenerating water stabilization technology comprises the following steps: the method comprises the steps of adopting a hydraulic crusher to crush an old cement concrete pavement panel into large concrete blocks of about 50cm, then using mobile crushing equipment to crush the large concrete blocks into continuous recycled aggregate with moderate size and gradation, then using a cement spreading vehicle to add a certain amount of cement, using a recycling machine to add water (if necessary, a certain proportion of new aggregate) to carry out covering and stirring to form a recycled mixture meeting the index requirements of a water stabilization layer, and finally carrying out rolling and curing to form a new water stabilization layer. The main process flow is shown in figure 1.
The used old cement concrete crushing equipment is an MR130 type full-depth movable crusher;
the calculation methods of the water content, the water adding amount and the cement amount are as follows: an external doping method;
the cement used was: P.O 42.5 cement, the dosage is 4.5%;
the test protocol used was: test code for inorganic binder stabilizing materials for road engineering JTG E51;
the technical standards adopted are as follows: detail rule of construction technology of highway base course JTG/T F20;
s1, selection of optimal gradation
Examples 1 to 3
3 kinds of old cement concrete plates are crushed into regenerated mixed aggregates according to the clearance rates of 80% and 90% of the maximum particle size by a full-depth movable crusher, and screening tests are carried out, wherein the test results are shown in the attached figures 2-3.
As can be seen from the test results of the examples 1 to 3, when the clearance ratio is 80% of the maximum particle size, the grading of the examples 1 to 3 is closer to the standard median value; when the clearance ratio is 90% of the maximum grain size, the grading of the embodiment 1-3 of the application is closer to the lower limit of the specification, and part of gears exceed the requirement of the lower limit of the specification. Therefore, 80% of the maximum particle size was selected as the optimum gap ratio, and the regenerated mixed aggregate of the gap ratio was subjected to the relevant performance test, and the main test results are shown in the following table.
| Detecting items | Technical index | Example 1 | Example 2 | Example 3 |
| Crush value/%) | ≤30 | 16.3 | 16.6 | 19.8 |
| Content of synthetic needles/%) | ≤20 | 11.5 | 11.1 | 12.2 |
| Content of soft stone/%) | -- | 1.6 | 1.5 | 1.9 |
| Particle content of < 0.075mm | ≤20 | 11.7 | 11.1 | 13.7 |
| Index of plasticity | ≤17 | 5.2 | 5.4 | 5.9 |
| Synthetic apparent relative density | -- | 2.641 | 2.648 | 2.611 |
| Synthetic water absorption/% | -- | 3.9 | 3.6 | 6.3 |
It can be seen from the above table that when the gap ratio is 80% of the maximum particle size, the related performance of the embodiments 1 to 3 can meet the requirements of the related technical standards, and can meet the technical requirements of the water stabilization layer.
S2, influence of water absorption of regenerated mixed aggregate on compaction result and solution
Examples 4 to 5
The reclaimed aggregate was placed indoors and its air-dried moisture content was found to be constantly changing. Therefore, the regenerated mixed aggregates of examples 1 and 3 were uniformly spread in a dish, dried and cooled, and then placed in a room, and the change in mass thereof was observed, and the observation results are shown in fig. 4.
And (4) conclusion: as can be seen from the test results of example 4, the observation results of the first 24 hours show that the water absorption of the dried regenerated mixed aggregate is continuously increased along with the time extension, and the total trend of first-speed and second-speed is presented; comparing the observation results of 24h, 48h and 72h, after the sample is fully air-dried, the air-dried moisture content of the sample still changes along with the change of the temperature and the humidity every day. It can be seen that if the duration of the compaction test is long, the air-dried moisture content of each sample may be different, thereby affecting the stability of the compaction result. Therefore, in order to ensure that the air-dried moisture content of the reclaimed aggregate is kept consistent during compaction, each sample is sealed with a plastic bag immediately after sample separation for future use.
S3, influence of compaction quality of mixed materials on compaction results and solution
Comparative example 1
In order to better embody the characteristic of high water absorption of the regenerated aggregate, the regenerated mixed aggregate in example 3 is selected to be subjected to a conventional heavy compaction test, the soaking time is 3h, and the test result is shown in the following table and fig. 4.
(1) Mass of remaining sample = mass of dry aggregate-actual amount of sample taken out
As can be seen from the above table and FIG. 4, when the conventional heavy compaction test method is used for compaction test of the recycled mixture with high water content, the water content and the dry density of 5 samples are not obviously regular, and a complete convex curve cannot be formed. The reason is that the optimum water content of the reclaimed aggregate is large, the actual dosage of the sample participating in the compaction test is only about 4.0kg, the difference with the conventional heavy compaction test method is large when the mass of each sample is 5.5kg, and the gradation of the residual sample of about 1.5kg is difficult to keep consistent, so that the accuracy of the compaction result is influenced.
Comparative example 2
After reducing the mass of the reclaimed mix to 4200g based on the actual amount of the tapped sample obtained in comparative example 1, a conventional heavy tapping test was performed, and the test results are shown in the following table and fig. 5.
And (4) conclusion: from the test results of comparative example 1 and comparative example 2, it can be seen that the compaction curve obtained by the heavy compaction test using the actual amount of the recycled sample is more regular and can form a complete convex curve.
S4, influence of infiltration time of regenerated aggregate on compaction result and solution
Example 4
The present application performed 5 groups of the reclaimed mixed aggregates of example 3 in heavy compaction tests at different infiltration times, the test results are shown in table 6 below.
| Soaking time/ |
0 | 30 | 60 | 120 | 180 |
| Optimum Water content/%) | 9.8 | 10.0 | 10.3 | 10.6 | 10.8 |
| Maximum dry density/(g/cm) 3 ) | 1.950 | 1.952 | 1.950 | 1.948 | 1.948 |
And (4) conclusion: test results show that the optimal water content of the mixture is gradually increased along with the increase of the infiltration time, and the overall rule of first-speed and second-speed is presented, because the regenerated mixture has the characteristics of high water absorption rate and high water absorption rate, and the water absorption capacity of the aggregate is gradually saturated along with the increase of the time, and the water absorption rate is gradually slowed down; as the water absorbed into the aggregates is gradually increased, the moisture between the aggregates is gradually reduced, and more water needs to be added to maintain the optimal moisture content; during the water content test, water between aggregates and water sucked into the aggregates are dried, so that the measured water content is gradually increased; however, since the mass of the dry sample was not increased, the maximum dry density did not change much. When compaction tests are carried out on the regenerated mixture with a high water absorption rate, the regenerated mixture does not need to be soaked, and cement and water can be directly added for mixing.
S5, influence of distribution positions of large aggregates in the recycled aggregates on compaction results and solution
The situation that large aggregates are just positioned at the top of a cylinder and cannot be scraped off commonly exists in a conventional heavy compaction test, and the large aggregates are removed, so that the local structure of the surface of a compacted test piece becomes loose, the quality of a wet test material is reduced, and the maximum dry density is reduced; in actual operation, some technicians can intentionally leave a large amount of fine aggregates in the last layer to avoid the situation, but the feeding mode can cause a large amount of large aggregates in the middle of a test piece and is not consistent with the distribution state of recycled mixture granules on a construction site; meanwhile, aggregate gradation added in the 3 layers is uneven, so that the height of a compaction test piece and the representativeness of water content test sampling are influenced, and the accuracy of a compaction test is influenced.
Example 5
According to the actual dosage of the compaction sample of the comparative example 2, the recycled mixture of the example 3 is compacted by the optimized heavy compaction test method of the application, and the compaction results are shown in the following table and fig. 7.
And (4) conclusion: the test results of the embodiment 5 and the comparative example 2 show that the compaction test of the regenerated mixture by the optimized heavy compaction test method is more stable, and a more regular complete convex curve can be formed, which indicates that the method can improve the stability of the compaction test; meanwhile, the maximum dry density obtained by the method is improved compared with that obtained by a JTG E51-2009 T0804C method, which shows that the method can eliminate the influence of structural looseness caused by large aggregates at the top of the cylinder on compaction results and improve the accuracy of compaction tests.
S6, influence of material distribution mode on unconfined compressive strength test result and solution
Example 6
To further verify the feasibility of the method, 7d unconfined compressive strength tests were performed according to the results of the compaction test of comparative example 2 and example 5, respectively, and the results are shown in the following table.
Note: the sample dividing method comprises the steps of dividing a sample with the standard mass of 16 times of that of a single test piece into 16 uniform sample parts by using a sample divider, and immediately sealing the sample parts by using a plastic bag.
And (4) conclusion: as can be seen from the test results in the table above, the 7d unconfined compressive strength representative values obtained from the two compaction results both meet the technical requirements of JTG/T F20-2015; the average value of the compressive strength obtained by the compaction result of the method is slightly larger than that of the C method, but the representative value is 0.6MPa larger than that of the C method because the coefficient of variation of the method is smaller. This further illustrates that the compaction test of the recycled mixture by the method can indeed obtain more reliable compaction results; meanwhile, the sample obtained by the sample dividing method is proved to be more uniform, and the compaction result and the unconfined compressive strength test result are better.
The above description is only a part of examples and comparative examples of the present invention and should not be construed as limiting the present invention, and any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The method for optimizing the mix proportion of the in-situ broken recycled water-stabilized layer of the old cement concrete of the pavement is characterized by comprising the following steps of: the method comprises the following steps:
s1: determining the optimal gradation of the regenerated aggregate and the optimal clearance rate of the crusher according to the screening test result of the regenerated mixed aggregate obtained by crushing with different clearance rates;
s2: setting cement dosage according to design requirements, and if the cement dosage is not required, setting different cement dosages; mixing a regenerated mixture according to different water consumption preset by the water absorption of the regenerated aggregate;
s3: distributing materials by using a distributor, and performing trial impact on the regenerated mixture according to a conventional heavy impact method to determine the actual consumption of a compacted sample required by a compacted test piece with the height of 12.0 cm;
s4: distributing the regenerated aggregate by using a distributor according to the actual using amount of the compaction sample, and adding cement and water for mixing; carrying out heavy compaction tests with different water contents on the sample by adopting a compaction cylinder with the height of 17.6cm, leveling by using a sand paving method, and calculating and analyzing a curve to obtain the optimal water content and the maximum dry density;
s5: and manufacturing a cylindrical test piece according to the optimal water content and the maximum dry density, performing a 7d unconfined compressive strength test, and determining the mixing ratio of the reclaimed water stable layer.
2. The mix proportion optimization method for the old pavement cement concrete on-site crushing and regenerating water-stabilizing layer according to claim 1 is characterized by comprising the following steps of: in S1, the clearance rate is the ratio of the clearance between a counterattack frame and a rotor frame of the crusher to the maximum grain diameter, continuous graded recycled aggregates meeting the standard JTG/TF20-2015 grading and performance requirements can be directly obtained by adjusting the clearance rate of the crusher, and the optimal grading can be selected and determined only by comparing the results of screening tests and performance tests of the recycled mixed aggregates with different clearance rates.
3. The mix proportion optimization method for the old pavement cement concrete on-site crushing and regenerating water-stabilizing layer according to claim 1 is characterized by comprising the following steps of: the water consumption in S2 is different according to the preset water absorption rate and is generally +2% -5% of the synthetic water absorption rate of the regenerated aggregate.
4. The mix proportion optimization method for the old pavement cement concrete on-site crushing and regenerating water-stabilizing layer according to claim 1 is characterized by comprising the following steps of: the material is divided by the material divider in S3, the method is that the sieved sample is gradually divided by a quartering method until about 8 times of the actual dosage of the sample is finally taken; dividing the sample into 8 parts by a distributor, wherein each part has the same mass as the actual dosage, drying and cooling the sample, and sealing with a sealing bag for later use.
5. The old pavement cement concrete in-situ breaking method according to claim 4The mix proportion optimization method of the crushed reclaimed water stable layer is characterized by comprising the following steps: in S3, the actual dose of the proof test sample = (m) 1 -m 2 ) /(1 + 0.01w)/(1 + 0.01c), wherein: m is 1 The total mass of the test cylinder and the wet test material; m is 2 The quality of the test cylinder; w is the water content of the sample; c is the mixing amount of the stabilizer in the mixture.
6. The mix proportion optimization method for the old pavement cement concrete on-site crushing and regenerating water-stabilizing layer according to claim 1 is characterized by comprising the following steps of: and S4, the mixing method comprises the steps of flatly paving 1 part of the sample on a clean plane, adding cement with a preset dose into the sample, uniformly mixing the sample with a small shovel, uniformly spraying water with the mass which is calculated to obtain the sample to be added on the sample with the cement, and fully mixing the sample to be in a uniform state with the small shovel.
7. The mix proportion optimization method for the old pavement cement concrete on-site crushing and regenerating water-stabilizing layer according to claim 6, is characterized in that: s4, the compaction cylinder has the size of 15.2cm of inner diameter, 17.6cm of height and 2286cm of volume 3 (after deducting a cushion block with the height of 5 cm), each charging in the compaction process is about 1/3 of the actual dosage.
8. The mix proportion optimization method for the old pavement cement concrete on-site crushing and regenerating water-stabilizing layer according to claim 7 is characterized by comprising the following steps of: in the heavy compaction test in the S4, after 3 layers of test materials are compacted, scraping the test materials adhered to the inner wall of the lantern ring by using a scraper, twisting and taking down the lantern ring; wiping the joint of the cylinder top and the lantern ring and the outer wall of the test cylinder, removing the bottom plate, taking away the cushion block, and weighing the mass m 1 (ii) a Slowly adding dry sand of 0.3-0.6 mm from the top of the compaction cylinder until the dry sand completely covers the top; scraping the sand with the top of the cylinder carefully, wiping off the joint between the cylinder top and the lantern ring and the outer wall of the test cylinder, and weighing the mass m 3 (ii) a Pouring out the dry sand on the top of the cylinder, pushing out the sample in the cylinder by a stripper, removing the sand attached to the top of the compacted sample by a scraper and a soft brush, crushing the rest part by a hammer, loading into a tray, and putting into an oven which is adjusted to 105-110 ℃ in advance to measure the water content of the water-contained sampleAmount, calculated to 0.1%; wiping the test tube to obtain a mass m 2 。
9. The mix proportion optimization method for the old pavement cement concrete on-site crushing and regenerating water-stabilizing layer according to claim 8 is characterized in that: the calculation formula in S4 is the calculation of the wet density of the stabilizing material:
ρ w ＝(m 1- m 2 )/[V-(m 3 -m 1 )/ρ s ]
in the formula: rho w Wet density (g/cm) of the stabilising material 3 )；
m 1 -total mass of cartridge and wet sample (g);
m 2 -mass of cartridge (g);
v- -compacting cylinder volume (cm) 3 )
m 3 -mass (g) of test cylinder, wet test sample and sand;
ρ s -the apparent density of the sand (g/cm) 3 )。
10. The method for optimizing the mix proportion of the old pavement cement concrete crushed in situ to regenerate the water-stabilizing layer is characterized by comprising the following steps of (1); the material dividing method for manufacturing the cylindrical test piece in the S5 is characterized in that 16 times of standard mass of a single test piece is divided into 16 parts of uniform test pieces by a material divider, the uniform test pieces are immediately sealed by a plastic bag, and 13 parts of the uniform test pieces are randomly selected for carrying out an unconfined compressive strength test.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116663378A (en) * | 2023-05-23 | 2023-08-29 | 合肥工业大学 | Grading optimization method considering morphology of reclaimed sand particles |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106738205A (en) * | 2016-12-23 | 2017-05-31 | 长安大学 | A kind of cement stabilizing crushing gravel mixing proportion design method based on vibration test |
| CN106977148A (en) * | 2017-04-24 | 2017-07-25 | 广州大学 | A kind of cement stabilized recycled concrete aggregate rubble proportion design method |
| CN112326943A (en) * | 2020-10-30 | 2021-02-05 | 山东洁诺环境科技有限公司 | Mix proportion design method of cement stable regeneration aggregate subbase |
-
2022
- 2022-12-28 CN CN202211696093.7A patent/CN115925342A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106738205A (en) * | 2016-12-23 | 2017-05-31 | 长安大学 | A kind of cement stabilizing crushing gravel mixing proportion design method based on vibration test |
| CN106977148A (en) * | 2017-04-24 | 2017-07-25 | 广州大学 | A kind of cement stabilized recycled concrete aggregate rubble proportion design method |
| CN112326943A (en) * | 2020-10-30 | 2021-02-05 | 山东洁诺环境科技有限公司 | Mix proportion design method of cement stable regeneration aggregate subbase |
Non-Patent Citations (2)
| Title |
|---|
| 沙庆林: "《水泥稳定土基层和底基层》", 31 May 1981, 人民交通出版社, pages: 176 - 187 * |
| 赵再琴，李建华，赵红: "《建筑材料》", 31 October 2020, 北京理工大学出版社, pages: 228 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116663378A (en) * | 2023-05-23 | 2023-08-29 | 合肥工业大学 | Grading optimization method considering morphology of reclaimed sand particles |
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