CN113445390A

CN113445390A - Pavement construction and quality control method for rapid open traffic in heavy traffic low-temperature environment

Info

Publication number: CN113445390A
Application number: CN202110716544.8A
Authority: CN
Inventors: 周晓华; 张伟; 李秀君; 鲁蓓蕾; 周志远; 陈磊; 张洁; 索郧; 曹芬; 胡磊; 朱诚承; 徐龙; 李开明
Original assignee: Wuhan Jiangxia Road And Bridge Engineering Corp
Current assignee: Wuhan Jiangxia Road And Bridge Engineering Corp
Priority date: 2021-06-28
Filing date: 2021-06-28
Publication date: 2021-09-28

Abstract

A pavement construction and quality control method for rapidly opening traffic in a heavy traffic and low temperature environment, comprising: firstly determining a raw material ratio of a cold recycled mixture for pavement, the raw materials include a first group of materials and a second group of materials, and the first group of materials. One group of materials includes: new aggregates, cement and asphalt mixture recycling materials; the second group of materials includes: foamed asphalt, mixing water; road cleaning, spreading new aggregates, spreading cement, recycling operations, paving, pressing Solid, seam, wellness and open to traffic. There is a construction and quality control method for specific foamed asphalt in-situ cold recycled materials, which can effectively avoid the segregation of the mixture, and can quickly open the traffic, and finally obtain the heavy weight of the underlying layer of high-quality asphalt pavement. The advantages of fast opening of traffic in low temperature environment of traffic.

Description

Pavement construction and quality control method for rapid open traffic in heavy traffic low-temperature environment

Technical Field

The application relates to the technical field of asphalt mixtures, in particular to a pavement construction and quality control method for rapidly opening traffic (2 hours) in heavy traffic low-temperature environment (the lowest temperature can be realized at 10 ℃).

Background

According to the condition of building roads in China at present and the design life of asphalt pavements, a certain proportion of asphalt pavements in China enter a middle and large maintenance period, the problems that the old materials are not reasonably utilized, the pavement materials and energy consumption are large and the like exist in the traditional maintenance method, a pavement regeneration technology which can maintain the normal operation of roads, can reasonably dispose the waste pavement materials and is more economical and applicable is urgently needed, and a foamed asphalt cold regeneration technology is produced at the same time.

Although the trial application of the foamed asphalt cold recycling in situ is started as early as 2005 in China and then the popularization and application are carried out in various parts of China, the foamed asphalt cold recycling mixture is mainly applied to light traffic and low-grade pavements and mainly used as a base layer in high-grade roads and the application of the foamed asphalt cold recycling mixture to heavy traffic asphalt pavement pavements is still blank due to the limitations of equipment and processes and the immature design method of the cold recycling mixture, so that the application and development of the technology are severely limited.

In addition, the existing foamed asphalt is mainly used for low-grade road surfaces of light traffic in a cold in-place manner, and is mainly used as a base layer in high-grade roads. The limitations are mainly reflected in: (1) the research on the foamed asphalt cold-recycling mixture is not deep enough, for example, the grading range of the mixture is too wide, and the quality of a finished product material cannot be effectively controlled; the performance evaluation index of the mixture cannot adapt to specific application occasions and the like; (2) the tire-based cold in-place recycling machine is directly paved on a road after milling and mixing, and segregation of grading of recycled mixture is inevitable; meanwhile, the process needs a grader for leveling, the surface of the regeneration layer is easy to separate, and the surface flatness and the like are difficult to control; (3) the regeneration width of one time can only reach 2.4m, and the regeneration construction of one lane of 3.75m can not be completed, so that more longitudinal and transverse joints are caused, the construction efficiency is low, and the construction requirement of a road with large traffic volume is difficult to meet.

Disclosure of Invention

The construction and quality control method can effectively avoid segregation of the mixture, can open traffic quickly, and finally obtains the pavement construction and quality control method for quickly opening traffic under the heavy traffic low-temperature environment of the lower surface layer of the high-quality asphalt pavement.

In order to solve the technical problem, the technical scheme adopted by the application is as follows: a pavement construction and quality control method for fast open traffic in a heavy traffic low-temperature environment comprises the following steps:

(1) firstly, determining the raw material ratio of a cold-recycling mixture for a road surface, wherein the raw materials comprise a first group of materials and a second group of materials, and the first group of materials comprise: a new aggregate, cement and asphalt mixture reclaimed material; the second group of materials comprises: foamed asphalt and water for mixing;

(2) cleaning the road surface: cleaning the road surface before in-situ cold regeneration construction, and keeping the road surface clean and flat; construction lofting: utilizing lime to scratch regeneration edge lines or arranging stake marks on two sides of a road as base lines;

(3) spreading new aggregate: spreading with spreading vehicle, wherein the spreading amount should be calibrated on site or controlled locally according to the total amount per 100m²-300m²The total amount of the area is controlled, and the spreading thickness is uniform;

(4) spreading cement: spreading cement by using a spreading vehicle;

(5) regeneration operation: milling, crushing and mixing the pavement spread with the new aggregate and the cement according to the set regeneration depth; the regeneration construction speed is 4-6 m/min; the regeneration action process is that the road petroleum asphalt, the foaming asphalt and the water are mixed together in a regenerator according to the formula proportion in the step (1), and then the regeneration construction is carried out, wherein the mixing temperature is as follows: the temperature is 6-8 ℃ higher than the natural temperature;

(6) paving: paving the mixed material obtained in the step (5) by using a paver, wherein the paving speed is controlled to be 2-4 m/min, and the loose paving coefficient of the cold recycling machine mixture is 1.2-1.4; paving temperature: the temperature is 5-7 ℃ higher than the natural temperature;

(7) compacting: the surface of the cold recycling layer should be kept wet all the time in the rolling process; adopting a compacting process flow of initial pressing, secondary pressing and final pressing;

(8) seaming: longitudinal seaming and transverse seaming operations;

(9) health preserving and traffic opening: when the health is maintained under the condition of traffic opening, the regeneration layer quickly opens the traffic after finishing rolling, and the driving speed is controlled within 40 km/h; and uniformly spraying slow-breaking emulsified asphalt on the regenerated layer, wherein the spraying amount is 0.15-0.25Kg/m after being compared with that of the asphalt²And the traffic can be opened after demulsification.

Preferably, the raw material mixture ratio of the cold recycling mixture for the pavement in the step (1) specifically comprises: the raw materials of the mixture comprise a first group of materials and a second group of materials, wherein the first group of materials comprise: 15-20 parts of new aggregate, 1.5-2.0 parts of cement and 78-85 parts of recycled asphalt mixture; the second group of materials comprises: the water-based recycled asphalt mixture comprises foamed asphalt and mixing water, wherein the foamed asphalt accounts for 1.5-3.0 parts by weight, and the mixing water is added in an amount which enables the water content of the final recycled mixture to be 3.6-7.3%; the composite gradation determined by the reclaimed asphalt gradation, the new aggregate gradation and the cement gradation of the asphalt mixture meets the passing rate of not less than 3.0 percent when the passing rate is 0.075 mm; the grade of the reclaimed asphalt mixture after extraction and the synthetic grade of the new aggregate meet the requirement that the passing rate of 4.75mm is not higher than 45 percent.

Preferably, step (3) spreads the new aggregate: the spreading amount is per 100m²-300m²The total amount of the area is controlled, and the spreading thickness is uniform; converting the spreading channels of the spreading vehicle into the cement consumption with corresponding width, wherein the cement spreading is required to be uniformly distributed on the longitudinal section, and the cross section does not need to be completely covered; the depth of the original asphalt pavement milled in the step (5) is 0-35 cm, and the milling thickness is as follows: 10-15 cm.

Preferably, paving in step (6): paving the mixed material obtained in the step (5), wherein the transverse slope and thickness are controlled, and the paving flatness and thickness are controlled in a balance beam guiding mode; the spiral feeder in the paving process storage box is always buried at the height of the cold recycling mixture which is not less than 3/4, so that the segregation of the cold recycling mixture in the paving process is reduced.

Preferably, step (7) comprises: the surface of the cold recycling layer should be kept wet all the time in the rolling process; the method adopts a compacting process flow of initial pressing, secondary pressing and final pressing, and comprises the following steps: adopting a 13t double-steel-wheel road roller for 1-3 times, wherein the rolling speed is 1.5-3 km/h; the first time adopts a forward static pressure mode, and the other times adopt vibration rolling, and the rolling is carried out from the outer side of the road to the center of the road; repressing: vibrating and compacting for 3-5 times by a single steel wheel of 26t at the rolling speed of 2-4 km/h; kneading for 4-6 times at 30t rubber-tyred roller static pressure, and rolling at 2-4 km/h; final pressure: the static pressure of the 13T double-steel-wheel road roller is 1-2 times, and the rolling speed is 2-4 km/h; compacting temperature: the natural temperature is 3-6 ℃ higher.

Preferably, the longitudinal seam of step (8): the width of the first regenerating operation is consistent with the milling width, and the longitudinal lap width of all subsequent effective regenerating breadth is 5-10 cm; then carrying out longitudinal seam rolling, wherein 1/2 wheel width is required to carry out cross seam rolling to eliminate stitches; when the longitudinal joint is formed by dividing into two half-width, firstly, the vehicle is driven on the pavement, then the new pavement is rolled by 10cm-15cm, and then the compaction wheel is stretched by 10cm-15cm of the compacted surface for compaction.

Preferably, the transverse seam of step (8): when a working day is finished, the two connected working sections are connected, the tank car is replaced in the process of regeneration or the machine is stopped due to other conditions, and a transverse seam is formed; before the operation is restarted, the whole regeneration unit is required to retreat to the regenerated section for at least 1.5 meters to ensure that the mixture on the seam width is treated; for the road section exceeding the initial set of cement, spreading cement again at the joint, but not spreading broken stones and spraying foamed asphalt; when rolling the transverse seams, transversely driving a vehicle on the formed road width, rolling a new layer by 10-15 cm, moving the new layer to the new paved mixture by 15-20cm after each rolling until the new paved layer is completely rolled, and then longitudinally rolling, and fully compacting the seams tightly.

Preferably, the slow-breaking emulsified asphalt is a slow-breaking emulsified asphalt liquid diluted to 25-35% of the solid content of the asphalt, and the spraying amount is 0.20Kg/m after the spraying amount is reduced to the asphalt²。

The application has the advantages and beneficial effects that:

1. the application is to construction and quality control that specific cold recycled mix goes on, the cold recycled mix of this application adopts two kinds of grades to establish "closely knit" type structure model of skeleton, one of them grade is to adopt foamed asphalt to be as main binder and cement and be supplementary binder (regenerant), another kind of grade is to adopt bituminous mixture reclaimed materials (RAP to mill the planer material), new aggregate, then above-mentioned material mixes with water at the construction road surface, then through milling and planing, mixing, pave, roll, form the bituminous stabilization material BSM of closely knit type half gentle half rigid structure of skeleton, this mixture porosity 8.0 ~ 13.0%, the best water content is 5.7%, maximum dry density 2.072g/cm³(ii) a This particular cold-recycling mix has the purpose of opening the traffic after a short time, i.e. two hours, and even in a low temperature environment (even if the minimum temperature reaches 10℃.)But can meet the requirement of opening traffic in the time; in particular, in order to realize the opening of traffic as soon as possible, slow-breaking emulsified asphalt (diluted to about 30% of asphalt solid content) is uniformly sprayed on a regeneration layer, the spraying amount is preferably 0.2Kg/m2 after being compared with the asphalt, and the traffic can be opened after demulsification (about 2 hours).

2. According to the method, a specific construction process method is adopted through a specific regeneration mixture, an obtained target road layer can meet the use requirement of a lower surface layer of the heavy-duty asphalt pavement, a WEITHEN 3800CR/W380CR in-situ cold regenerator is used for milling and mixing one lane at a time, then a paver is used for synchronous paving, a road roller is used for compacting, the obtained regeneration layer can open traffic quickly, and the lower surface layer of the high-quality asphalt pavement is finally obtained.

3. According to the compacting step, a three-section compacting process is adopted, so that the strength and compactness of a forming surface can be effectively enhanced, and guarantee can be provided for rapid opening of traffic in the later stage.

4. The construction and quality control method combines specific mixture ratio, and the obtained regeneration layer is flat and compact in surface, free of depression and fine segregation; the surface has no floating soil, spring and other phenomena; the construction joint is smooth and stable.

5. The construction and quality control method can fully utilize the old mixture of the original pavement, only a small amount of asphalt, cement and new aggregates are needed to be added (only coarse aggregates with the grain size of 9.5-26.5mm are needed, and the construction and quality control method is different from the traditional coarse and fine aggregates in use by controlling different aggregate combinations), thereby greatly reducing the construction cost; can realize 100 percent recovery and utilization of old materials, reduce the damage to surface vegetation caused by stone mining and avoid the land occupation pollution of solid waste sites.

Drawings

FIG. 1 shows the principle of cold regeneration technology of high-performance in-situ foamed asphalt.

FIG. 2 shows the principle of cold regeneration of high-performance in-situ foamed asphalt.

Figure 3 is a process flow diagram.

Detailed Description

The following examples are not provided to limit the scope of the present invention, nor are the steps described to limit the order of execution. Modifications of the invention which are obvious to those skilled in the art in view of the prior art are also within the scope of the invention as claimed.

When the foamed asphalt is 1.5-3.0 parts by weight based on 100 parts of the first group of materials, the foamed asphalt takes 100 parts of the first group of materials as the corresponding addition amount of the whole; the above-mentioned parts by weight can also be regarded as the content of weight percent, the sum of the weight percent of each component in the first group of materials is 100 percent, wherein the foamed asphalt can be regarded as 1.5 to 3.0 percent of the total weight of the first group of materials; when parts by weight, the sum of the parts by weight of the individual components of the first group of materials in this application is 100 parts.

Examples

The formulation of the reclaimed blend used in this example is as follows:

the application discloses high performance foam asphalt is cold in place and is recycled mixture, the raw materials of this mixture include first group material and second group material, first group material include: 18 parts of new aggregate (gravel) (the new aggregate is made of gravel with the grain diameter of 9.5-26.5 mm), 1.8 parts of cement and 80.2 parts of recycled asphalt mixture; the second group of materials comprises: 2.4 parts by weight of foamed asphalt (the parts by weight of the foamed asphalt correspond to the parts by weight of the first group of materials when the foamed asphalt and the first group of materials are taken as a whole), wherein the addition amount of the mixing water is such that the water content of the final recycled mixture is 5.7%; the composite gradation determined by the reclaimed asphalt gradation, the new aggregate gradation and the cement gradation of the asphalt mixture meets the passing rate of not less than 7.6 percent when the passing rate is 0.075 mm; the grade of the reclaimed asphalt mixture after extraction and the synthetic grade of the new aggregate composition meet the passing rate of 44 percent of 4.75 mm.

Specifically, the formula components meet the following requirements: tests prove that the water content of the milling material of the pavement to be constructed in the embodiment is 1.6 percent (reclaimed asphalt mixture), the optimal water content of the foamed asphalt cold-recycling mixture is 5.7 percent, and the maximum dry density is 2.072g/cm³In situ cooling of recycled mixturesThe thickness of the regenerated layer formed by paving is 10cm, and according to the dosage per square:

milling materials: 2.072 0.1 80.2% ═ 166kg/m²；

25 crushed stone (new aggregate or called new aggregate): 2.072 0.1 ═ 18%²；

Cement: 2.072 0.1 1.8% ═ 3.370kg/m²；

Asphalt: 2.072 0.1 2.4% ═ 4.973kg/m²；

Water consumption (i.e. mixing water) added: 2.072 × 0.1 × 5.7% -166 × 1.6% -4.973 × 2.5% ═ 9.02kg/m 2; wherein the additional water consumption is adjusted according to the change of the water content of the milling material; wherein the proportion of the externally added water is the optimum water content minus the water content in the milling material and the new aggregate, and the dosages of the foamed asphalt and the water are the externally added proportion.

The construction method comprises the following specific construction steps:

(1) spreading new aggregate

The new aggregate should be kept dry, and should be spread by using a spreading vehicle, and the spreading amount of the aggregate should be calibrated on site or controlled by local total amount. Optionally, manual spreading may be adopted, but the manual spreading should be performed on the road surface in advance by using lime powder, preferably per 100m²-300m²The total amount of the area is controlled, and the spreading thickness is uniform.

(2) Spreading cement

The spreading vehicle is adopted for spreading, and the cement spreading amount is calibrated on site or controlled by local total amount. When the cement spreading vehicle is generally 2.5m wide and the regeneration width is 3.8m or 4.5m, the spreading lane of the spreading vehicle is converted into the cement dosage with corresponding width, the cement spreading is required to be uniformly distributed on the longitudinal section, but the cross section can not be completely covered because the mixture is gathered to the position of the middle conveyor belt when the regenerating machine is milled and mixed. Once the cement spread is complete, vehicles other than the reclaimer must not enter the construction area on a uniform basis.

(3) Regeneration operation

1, determining the number of regeneration widths and the construction sequence according to the road surface and the mechanical construction width, sequentially connecting the regeneration units end to end at the construction starting point according to the designed cross slope, and connecting the regeneration units with corresponding pipelines.

2, starting construction preparation, milling and mixing the road surface according to the set regeneration depth. The regenerating unit must slowly, uniformly and continuously carry out the regenerating operation, the speed can not be changed randomly or stopped midway, the regenerating construction speed is selected from the regenerating machine, the type of the regenerating material and the regenerating depth, preferably 4-6 m/min, and is controlled to be about 5 m/min.

3 the operating speed of the player should be detected and recorded at least every 200m to ensure that the player maintains a certain production efficiency and good reproduction.

4 in straight line and not setting up the flat curve section of superelevation, the regenerating machine should begin along the outside of roadwidth at first, then construct to the inside of roadwidth gradually, set up the flat curve section of superelevation, the regenerating machine should begin along the inside of roadwidth at first, then construct to the outside of roadwidth gradually.

And 5, marking with talcum powder on a regeneration road or fixing a guide line on the edge of a working face to be used as a direction guide of the regenerator so as to ensure that the regenerator moves forward along the correct direction. When the cutting depth of the regenerator needs to be adjusted under special conditions, the cutting depth needs to be slowly adjusted (the cutting depth is adjusted within 3mm at one time) to avoid the phenomenon of obvious slab staggering and avoid the height difference when a subsequent paver paves.

6, arranging a specially-assigned person (technician) to continuously observe the uniformity of the regenerated mixture after following the regenerating machine, checking the regeneration thickness at any time, once the strip or agglomeration phenomenon of the asphalt is found, adjusting the water consumption for foaming, observing whether the wire drawing phenomenon is reduced or not, and immediately stopping construction if the wire drawing phenomenon is not changed.

After 7, a specially-assigned person (construction worker) is arranged to process the excess materials outside the boundary line and at the initial position of the regenerating machine, and the excess materials are discarded.

The original asphalt pavement is deep (0-35 cm), and milling is carried out: paving new aggregates, spreading cement and the original asphalt pavement depth (0-15 cm), and synchronously milling and crushing; milling to a thickness of 10 cm;

optimizing the grading of the regenerated material by adopting an undercut mode and then realizing synchronous operation with the paver by adopting a discharge mode; mixing: the spraying rod sprays water and foamed asphalt into the mixing bin, and at the same time, the milled new aggregate, cement and RAP material are uniformly mixed at normal temperature.

Or the mixing temperature is as follows: the environmental temperature (natural temperature) is 6-8 ℃ higher.

(4) Paving machine

And 1, during paving construction, paying attention to control transverse slope and thickness, and controlling paving flatness and thickness by adopting a balance beam guide mode.

2 during the paving process, the amplitude of the screed plate and the vibration frequency of the rammer are reasonably selected. Generally, the cold recycling mixture is preferably paved in a mode that the vibration frequency of a rammer is greater than the amplitude of an ironing plate so as to improve the initial compaction degree of the cold recycling mixture. The gap at the widened hinged position of the ironing plate is carefully adjusted to be tight, so that the trace on the surface of the paved road is prevented.

3 the paver must control the height of the material level sensor in the paving process, so that the spiral feeder in the material storage box is always embedded into the cold recycling mixture to be not less than 3/4, thereby reducing the segregation of the cold recycling mixture in the paving process.

4 the ironing plate of the paver must be spliced tightly without gaps, so that the phenomenon that the oil surface is pulled out of streaks by blocked materials is prevented.

5 during installation and operation of the paver, the anti-segregation measures of the mixture such as reducing the height above the ground of the front baffle of the distributing device and the like are adopted, a special person is arranged behind the paver to eliminate the segregation phenomenon, the concentrated part of the local coarse aggregate is shoveled, and the mixture is filled with a newly-mixed mixture.

6, the spreading is uniform and continuous, and the speed is controlled to be 2-4 m/min. Significant segregation, waviness, cracks, drag marks, etc. should be avoided.

The loose paving coefficient of the 7 cold recycling machine mixture is determined according to a test section, and is generally between 1.2 and 1.4.

8, flatness control: after paving, the quality inspector can detect the flatness by using a three-meter ruler in time, particularly the flatness of the starting and stopping positions of the paver, and can manually level the flatness in time when the flatness does not meet the requirements.

And 9, the paving thickness, the road arch and the cross slope are checked at any time in the paving process, and the problems are found and adjusted in time.

And (10) collecting materials at the longitudinal joint by using a manual push rake, so that the materials cannot be higher than the ground road surface when the road roller rolls.

After the paving is adopted, a rear discharging and receiving belt collects the foamed asphalt recycled mixture and conveys the foamed asphalt recycled mixture to a hopper of an asphalt paver, and the paver accurately and synchronously paves the foamed asphalt mixture according to the specified contour and elevation; a detachable steel baffle is additionally arranged in front of a hopper of the paver and matched with the discharging speed of the regenerator; paving temperature: the environmental temperature (natural temperature) is 5-7 ℃ higher.

(5) Compacting

1 the cold regeneration mixture is preferably rolled under the condition of the optimal water content, and the phenomena of spring, looseness, peeling and the like are avoided. The surface of the cold regeneration layer should be kept wet all the time during the rolling process, and if the water is evaporated too fast, the water should be sprinkled for supplement in time. However, the water amount should not be too large.

2 compacting process flow

1) Initial pressing: adopting a 13t double-steel-wheel road roller for 1-3 times, wherein the rolling speed is 1.5-3 km/h; the first pass adopts a forward static pressure mode, and the other passes adopt vibration rolling to roll from the outer side of the road to the center of the road.

2) Repressing: vibrating and compacting for 3-5 times by a single steel wheel of 26t at the rolling speed of 2-4 km/h; and (3) kneading for 4-6 times at a static pressure of the 30t rubber-tyred roller, wherein the rolling speed is 2-4 km/h.

3) Final pressure: and (3) carrying out static pressure on the 13T double-steel-wheel road roller for 1-2 times, and carrying out rolling at the rolling speed of 2-4 km/h.

3 for avoiding when rolling the mixture push and produce the hug, should roll the drive wheel towards the paver during rolling, from the outside to the center, then roll by low to high in the superelevation section, should roll the drive wheel from low to eminence on the ramp.

And 4, when no support is arranged at the edge of the road, reserving the width of 30-40cm at the edge, and after the road is pressed for the first time, placing most of the road roller on the ground mixed material road surface and then grinding the edge.

After the rolling of the cold-recycling mixture paved by 5 is finished, any vehicle is not allowed to pass for at least 2 hours, so that sufficient health preservation is ensured, and the surface of the recycling layer is prevented from being loose due to the running of the vehicle.

6, for local parts which cannot be compacted by large machines, a small vibratory roller is selected for rolling.

And 7, the compaction can be performed by adopting an oscillating roller which is a compaction method combining vibration and kneading. The kneading action can prevent surface cracking, make the compacted surface smoother and more compact, and improve the water penetration resistance of the surface layer. The vibration compaction process is smooth without impact, so that the aggregate is not easy to crush and the surface layer can be prevented from vibrating and loosening.

(6) Joint seam

1 longitudinal seam

1) Two adjacent regenerated webs should have a certain overlap width. The width of the first regenerating operation should be the same as the milling width, and the longitudinal lap width of all the subsequent effective regenerating webs is 5-10 cm. Generally, the thicker the regeneration layer, the greater the lap width; the larger the maximum particle size of the material, the larger the overlap width.

2) The recycling machine should be advanced accurately along the preset milling guiding line. If the deviation exceeds 10cm, the construction should be backed up immediately to the place where the deviation begins to appear and then be re-constructed along the correct milling guiding line (without adding water and cement). When the overlap width exceeds the effective spray width of the regenerator nozzles, the subsequent construction should close several spray nozzles to ensure that the overlap area is free of excess asphalt and water.

3) The position of the longitudinal joint should avoid the driving wheel track of the vehicle on the fast and slow lanes.

4) Longitudinal seam rolling, should be 1/2 rounds wide across the seam to eliminate stitches. When the longitudinal joint is formed by dividing into two half-width, firstly, the vehicle is driven on the pavement, then the new pavement is rolled by 10cm-15cm, and then the compaction wheel is stretched by 10cm-15cm of the compacted surface for compaction.

5) The thickness of longitudinal lap joint part is strictly controlled during regeneration of multiple frames to avoid height difference, which causes that rolling can not eliminate seam, multiple construction approaches paved road surface, and the paver is controlled by adopting a sliding shoe mode.

2 transverse seam

1) When a working day is finished, the transverse seam is formed when the two connected working sections are connected, the tank car is replaced in the process of regeneration or the shutdown is caused by other conditions. Before the operation is restarted, the whole regeneration unit is retreated to the distance of at least 1.5 meters of the regenerated road section so as to ensure that the mixture on the width of the joint is treated. For road sections beyond the initial set of cement, the joint should be re-paved with cement, but without spreading gravel and spraying foamed asphalt.

2) When rolling the transverse seams, transversely driving a vehicle on the formed road width, rolling a new layer by 10-15 cm, moving the new layer to the new paved mixture by 15-20cm after each rolling until the new paved layer is completely rolled, and then longitudinally rolling, and fully compacting the seams tightly.

3) Vertical joints are adopted for construction joints every day, flatness is detected by using a 3m ruler, and parts with insufficient end thickness and quality defects are chiseled manually so as to be connected into right-angled joints next time.

(7) Health preserving and open traffic

1 when the health preserving is carried out under the condition of closed traffic, natural health preserving can be carried out, and measures are not required to be taken generally.

2, when the health is maintained under the condition of open traffic, the regeneration layer can open the traffic after finishing rolling for at least 1d, but the passing of heavy vehicles is strictly limited, the driving speed is controlled within 40km/h, and the vehicles are strictly prohibited from adjusting hands and braking suddenly on the regeneration layer.

3 in order to avoid the damage of the open transport vehicle wheels to the surface layer of the regeneration layer, the regeneration layer is uniformly sprayed with slow-breaking emulsified asphalt (diluted to about 30 percent of the solid content of the asphalt), and the spraying amount is preferably 0.2Kg/m after being compared with the amount of the asphalt²After demulsification (about 2 hours), the traffic can be opened. And after 5d of operation, coring detection is carried out, the core sample is complete and compact, the dry splitting strength reaches 0.6MPa, and the standard requirement is met.

4 when the regeneration layer uses a core drilling machine with a drill bit with the diameter of 150mm, the complete core sample can be taken out or the water content of the regeneration layer is lower than 2 percent, and the curing can be finished.

TABLE 1 frequency and requirements of quality inspection items for mix for cold in place recycling

TABLE 2 foam asphalt in-place cold regeneration layer quality control Standard

Engineering quality inspection and assessment

The material gradation of the cold-recycling mixture is in accordance with the design requirements and the specification of the specification, and the dosage of the asphalt and the dosage of the cement are accurately controlled.

The foaming temperature, expansion rate and half-life period of the asphalt and various performance indexes of the mixture are strictly controlled to meet the design and specification requirements. During the production of the cold-recycling mixture, a Marshall stability test and a cleavage strength test are carried out every day.

The mixed cold-recycling mixture is uniform and consistent, and the phenomena of coarse and fine material separation and asphalt agglomeration or filamentation are avoided.

The surface of the cold regeneration layer is required to be compacted by rolling, dried and clean, has no floating soil, flatness and road arch, and meets the design requirements.

The testing and evaluation of the foamed asphalt cold recycling pavement engineering should meet the relevant regulations of the JTGF80/1 pavement engineering quality testing and evaluation.

Actual measurement item

The measured items of the foamed asphalt in-situ cold recycling are shown in the table 3.

TABLE 3 actual measurement of foamed asphalt recycled layer

Table 4 Performance test results of foamed asphalt Cold recycled mixture

The appearance quality of the obtained regenerated mixture pavement is checked, and the appearance quality of the in-situ cold regeneration layer of the foamed asphalt meets the following performances;

1) the surface is smooth and compact, has no depression and no detail segregation;

2) the surface has no floating soil, spring and other phenomena;

3) the construction joint is smooth and stable.

Examples of the applications

Lower layer application case of section XXX

By depending on engineering application of a XXX section road upgrading and upgrading project K1356+600-K1361+600 sections with the length of 5Km and a high-performance foamed asphalt cold-in-place regeneration technology for 11 days, compared with the traditional process, 61 ten thousand yuan is saved per kilometer, and the construction period is shortened. All indexes meet the requirements of relevant specifications through detection, the WEITEN 3800CR complete cold regeneration equipment is used successfully, traffic is good, and the problems of construction and traffic under heavy load and large traffic volume are successfully solved.

Meanwhile, the high-performance in-situ foamed cold-recycling mixture is used for raw material test analysis, mix proportion design, mechanical equipment and personnel allocation of the lower surface layer of the asphalt pavement, and a construction process, a health preserving method and a quality control method in the application process, and provides reference for applying the high-performance foamed asphalt in-situ cold recycling technology to major and medium maintenance engineering of large-traffic heavy-duty roads.

Engineering application of XXX section water damage repair and pavement major and middle repair

The XXX section is positioned in XXX environment and is a key road section on a gold channel connecting Anqing with Jiujiang and the like. Since the traffic of G105 Jingzhu line is rapidly increased along with the rapid development of economic society, the traffic of G105 Jingzhu line is rapidly increased, the traffic of vehicles exceeding the limits of XXX is greatly damaged, the road condition of XXX section is seriously damaged, the current situation is more road pavement diseases which are mainly expressed as pit grooves, quack, cracking settlement, longitudinal and transverse cracks and the like on the road surface, the comfort of driving is influenced by the road pavement diseases, certain potential safety hazards exist, and the traffic safety device cannot meet the requirements of 'rapidness, smoothness, comfort and safety' of modern traffic. In order to improve the driving safety, smoothness and comfort of the XXX section, the road surface overhaul and maintenance are carried out on the XXX section by the road administration in Susong county, and the total length of the route is 9.9 kilometers. The project is established by XXX investment construction, and is determined by engineering construction bidding to be marked as a general contract construction unit by XXX company, and the project responsible person is XX, wherein the high-performance foamed asphalt is cold-in-place regenerated, the special contract unit is XXX company, and the project amount is 92640 square meters.

Application of XXX section in pavement repair and maintenance engineering

The G328 Qilao line is an important national road in east-west transverse directions in China, the starting point is in Jiangsu and the ending point is at the old estuary in Hubei. S310 is an important east-west traffic channel provided in a road network of the southwest city, and is also an important connecting line between Huainan city and the longevity county, the traffic flow is large, and diseases appear on the road surfaces of part of the road sections, so that the maintenance is needed urgently. The road of the section for maintenance at this time is a XXX section, the total length is about 6.0km, the current situation level is a second-level road, the designed vehicle speed is 60km/h, and the road width is 9 m. The project is constructed by xxx investment, a project responsible person is xxx, and the project is determined to be a general engineering contract construction unit by engineering construction bidding and bid, wherein the project is marked as a project general contract construction unit. The special contract construction unit is xxx group limited company, and the project amount is about 53000m²。

Claims

1. a pavement construction and quality control method for rapidly opening traffic under a heavy traffic low temperature environment, is characterized in that: the method steps comprise:

(1) First determine the raw material ratio of the cold recycled mixture for pavement, the raw materials include a first group of materials and a second group of materials, and the first group of materials includes: new aggregates, cement and asphalt mixture recycled materials; The second group of materials includes: foamed asphalt, mixing water;

(2) Cleaning the road surface: The road surface must be cleaned before the on-site cold recycling construction to keep the road surface clean and smooth; Construction stakeout: Use lime to draw the regeneration edge line or set up stakes on both sides of the road as the baseline;

(3) Spreading new aggregates: spread by spreading truck, the spreading amount should be calibrated on site or controlled by local total amount, and the total amount should be controlled according to every 100m ² -300m ² area, and the spreading thickness should be uniform;

(4) Spreading cement: use a spreading truck to spread cement;

(5) Regeneration operation: Milling, crushing and mixing the pavement spread with new aggregates and cement according to the set regeneration depth; the regeneration construction speed is 4-6m/min; the regeneration process is to mix the road petroleum asphalt and foaming Asphalt and water are mixed together in the recycler according to the formula ratio of step (1), and then the regeneration construction is carried out. The mixing temperature is 6 to 8°C higher than the natural temperature;

(6) Paving: The material mixed in step (5) is used for paving construction with a paver, the speed of paving is controlled at 2-4 m/min, and the loose paving coefficient of the cold-recycling mixture is between 1.2 and 1.4. time; paving temperature: 5 to 7°C higher than the natural temperature;

(7) Compaction: The surface of the cold regeneration layer should always be kept wet during the rolling process; the compaction process of initial pressure, recompression and final pressure is adopted;

(8) Seam: longitudinal seam and transverse seam operation;

(9) Conservation and open traffic: When conserving under the condition of open traffic, the reclaimed layer should be quickly opened to traffic after rolling, and the driving speed should be controlled within 40km/h; and the slow-cracked emulsified asphalt should be uniformly sprayed on the reclaimed layer. , the spraying dosage should be 0.15-0.25Kg/m ² converted to asphalt, and traffic can be opened after demulsification.

2. the pavement construction and quality control method of rapidly opening traffic under the heavy traffic low temperature environment according to claim 1, is characterized in that: the raw material proportioning of the cold regenerated mixture for pavement described in the step (1) specifically comprises : The raw materials of the mixture include the first group of materials and the second group of materials, and the first group of materials includes: 15-20 parts by weight of new aggregates, 1.5-2.0 parts by weight of cement, and 78-85 parts by weight of recycled asphalt mixture The second group of materials includes: foamed asphalt, mixing water, the foamed asphalt is 1.5-3.0 parts by weight, and the mixing water is added in an amount such that the moisture content of the final recycled mixture is 3.6%～ 7.3%; the synthetic gradation determined by the asphalt mixture recycling material gradation, new aggregate grading and cement grading should meet the pass rate of 0.075mm and not less than 3.0%; the asphalt mixture recycling material after extraction The synthetic gradation composed of gradation and new aggregates should satisfy the pass rate of 4.75mm and not higher than 45%.

3. the pavement construction and quality control method of rapidly opening traffic under heavy traffic low temperature environment according to claim 1, is characterized in that: step (3) spreading new aggregate: spreading amount is carried out according to every 100m ^{2-300m 2} ^area total. Quantity control, the spreading thickness should be uniform; Step (4) The spreading road of the spreading truck should be converted into the cement dosage of the corresponding width, and the cement spreading should be evenly distributed on the longitudinal section, and the cross section does not need to be completely covered; The depth of the asphalt pavement is 0-35cm, and the thickness of the milling is: 10-15cm.

4. the pavement construction and quality control method of rapidly opening traffic under heavy traffic low temperature environment according to claim 1, is characterized in that: step (6) paving: the material mixed in step (5) is carried out paving construction, Care should be taken to control the cross slope and thickness, and the smoothness and thickness of the paving should be controlled by the balance beam guidance; Segregation of cold recycled mix during paving.

5. The pavement construction and quality control method for rapidly opening traffic under heavy traffic low temperature environment according to claim 1, is characterized in that: step (7) compaction: in the rolling process, the surface of the cold regeneration layer should always be kept moist; The compaction process of initial pressure, recompression and final pressure, initial pressure: 1-3 times of 13t double-drum road roller, rolling speed of 1.5-3km/h; the first pass adopts forward static pressure, and the other adopts vibration rolling Pressing, rolling from the outside of the road to the center of the road; re-pressing: 26t single steel wheel vibrating and compacting 3-5 times, the rolling speed is 2-4km/h; 2-4km/h; Final pressure: 13T double-drum road roller is statically pressed for 1-2 times, and the rolling speed is 2-4km/h; compaction temperature: natural temperature is 3-6℃ higher.

6. The pavement construction and quality control method for rapidly opening traffic under heavy traffic low temperature environment according to claim 1, is characterized in that: the longitudinal seam described in step (8): the width of the first regeneration operation should be the same as that of milling The planing width is the same, and the longitudinal overlap width of all subsequent effective recycled webs is 5-10cm; then longitudinal seam rolling should be carried out, and 1/2 round width should be rolled across the seam to eliminate seams; when divided into two halves to form longitudinal seams When sewing, first drive on the already compacted surface, then roll the new layer 10cm-15cm, and then extend the compaction wheel over 10cm-15cm of the compacted surface for compaction.

7. The road construction and quality control method for rapidly opening traffic under heavy traffic low temperature environment according to claim 1, it is characterized in that: the lateral seam described in step (8): when one working day ends, two connected operations Transverse joints will be formed if the section is connected, the tanker is replaced during the regeneration, or the shutdown caused by other situations; the entire regeneration unit should retreat to a distance of at least 1.5 meters from the regenerated section before restarting the operation to ensure that the mixture on the joint width is processed; In the road section beyond the initial setting of cement, re-spray cement at the joints, but do not spread gravel or spray foamed asphalt; when rolling the horizontal joints, drive horizontally on the formed road width, roll the new layer 10cm-15cm, and then Move 15-20cm to the newly-laid mixture every time the rolling is rolled, until all the rolling is on the new layer, and then change to vertical rolling to fully compact the seam.

8. The pavement construction and quality control method for rapidly opening traffic in a low temperature environment of heavy traffic according to claim 1, characterized in that: the slow-cracked emulsified asphalt is a slow-cracked emulsification diluted to a solid content of asphalt of 25-35% Asphalt liquid, the spraying amount is 0.20Kg/m ² after converting to asphalt.