CN111485468B - Premixed foam asphalt base layer and subbase layer in-situ cold regeneration construction method - Google Patents
Premixed foam asphalt base layer and subbase layer in-situ cold regeneration construction method Download PDFInfo
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- CN111485468B CN111485468B CN202010227776.2A CN202010227776A CN111485468B CN 111485468 B CN111485468 B CN 111485468B CN 202010227776 A CN202010227776 A CN 202010227776A CN 111485468 B CN111485468 B CN 111485468B
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C7/00—Coherent pavings made in situ
- E01C7/08—Coherent pavings made in situ made of road-metal and binders
- E01C7/18—Coherent pavings made in situ made of road-metal and binders of road-metal and bituminous binders
- E01C7/187—Repairing bituminous covers, e.g. regeneration of the covering material in situ, application of a new bituminous topping
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
- E01C19/02—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for preparing the materials
- E01C19/10—Apparatus or plants for premixing or precoating aggregate or fillers with non-hydraulic binders, e.g. with bitumen, with resins, i.e. producing mixtures or coating aggregates otherwise than by penetrating or surface dressing; Apparatus for premixing non-hydraulic mixtures prior to placing or for reconditioning salvaged non-hydraulic compositions
- E01C19/1004—Reconditioning or reprocessing bituminous mixtures, e.g. salvaged paving, fresh patching mixtures grown unserviceable; Recycling salvaged bituminous mixtures; Apparatus for the in-plant recycling thereof
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
- E01C19/02—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for preparing the materials
- E01C19/10—Apparatus or plants for premixing or precoating aggregate or fillers with non-hydraulic binders, e.g. with bitumen, with resins, i.e. producing mixtures or coating aggregates otherwise than by penetrating or surface dressing; Apparatus for premixing non-hydraulic mixtures prior to placing or for reconditioning salvaged non-hydraulic compositions
- E01C19/1059—Controlling the operations; Devices solely for supplying or proportioning the ingredients
- E01C19/1068—Supplying or proportioning the ingredients
- E01C19/1072—Supplying or proportioning the ingredients the solid ingredients
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
- E01C19/02—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for preparing the materials
- E01C19/10—Apparatus or plants for premixing or precoating aggregate or fillers with non-hydraulic binders, e.g. with bitumen, with resins, i.e. producing mixtures or coating aggregates otherwise than by penetrating or surface dressing; Apparatus for premixing non-hydraulic mixtures prior to placing or for reconditioning salvaged non-hydraulic compositions
- E01C19/1059—Controlling the operations; Devices solely for supplying or proportioning the ingredients
- E01C19/1068—Supplying or proportioning the ingredients
- E01C19/1077—Supplying or proportioning the ingredients the liquid ingredients
Abstract
The invention provides a construction method for premixing foam asphalt base layer and subbase layer in-situ cold regeneration, and relates to the technical field of road engineering. The method sequentially comprises the following steps: s1 traffic is closed; s2 preparing an original road; s3 the regeneration train set is in place; s4, paving the premixed material; s5 milling and mixing the mixture by a cold recycling machine; s6 spreading the regeneration mixture; s7 rolling; s8 seam processing; s9 preserving health. The method determines the demand of crushed stone, mineral powder, cement and foamed asphalt according to the quantity of the recycled aggregate milled on the original road, and calculates and determines the mixing water demand of the premixed material and the foamed asphalt by combining the optimal water content of the recycled mixture; and pre-mixing the water, the powdery cement, the crushed stone aggregate and the mineral powder which are calculated and determined according to the required amount of the pre-mixed additive to form the pre-mixed additive. The powdery cement is prevented from drifting, the cement, the broken stone aggregate and the mineral powder with the optimal proportion are effectively added, the optimal water content of the recycled mixture and the quality of the foamed asphalt are ensured, and the recycled mixture has high-quality performance indexes.
Description
Technical Field
The invention relates to the technical field of road engineering, in particular to a construction method for premixing type foamed asphalt base layer and subbase layer in-situ cold regeneration.
Background
With the rapid development of highway construction in China, the total mileage of asphalt roads increases year by year, and meanwhile, many asphalt roads built in the early stage enter the maintenance stage successively. By the planning construction period of 'twelve five', the construction speed and the maintenance speed of the asphalt road are basically kept equal. At present, the maintenance of asphalt pavement in China mainly adopts foam asphalt in-situ cold regeneration technology.
The cold in-place recycling of foamed asphalt refers to a technique of using asphalt recycling equipment to break old asphalt pavement materials in place, adding proper asphalt and modified materials, mixing and compacting, and building roads by using the old pavement materials as main materials. The foamed asphalt in-place cold regeneration technology is one of the development directions of pavement regeneration technologies actively adopted by all countries in the world in recent years due to the advantages of resource saving, pollution reduction, cost reduction and the like, the foamed asphalt in-place cold regeneration applies the regeneration cycle of waste pavement materials to the construction and maintenance of road infrastructure, changes waste into valuable, forms an industrial chain conforming to a circular economy mode, can avoid the occupation of waste materials on land and the pollution to the environment, can reduce the requirements on stone materials, asphalt and cement, and can effectively reduce the road building and maintenance cost.
However, various additives with the optimal proportion cannot be effectively and harmlessly added in the existing in-situ cold recycling construction process.
Disclosure of Invention
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides a premixed foamed asphalt base layer and a subbase layer in-situ cold regeneration construction method, which solves the problem that various additives with optimal proportion cannot be effectively and harmlessly added in the in-situ cold regeneration construction process.
(II) technical scheme
In order to achieve the purpose, the invention is realized by the following technical scheme:
a premixed foam asphalt base layer and subbase layer in-situ cold regeneration construction method sequentially comprises the following steps:
s1, traffic is sealed
Setting a notice board at each intersection of a regeneration road section one week before preparing an original road surface to remind drivers and pedestrians of closing the time of traffic; when the original road surface is constructed, the traffic is completely closed, and all vehicles are forbidden to pass; in the whole construction and maintenance process, the traffic of the regeneration road section is completely sealed; a warning board is arranged on the unreproduced road section to remind a driver and pedestrians;
s2, original road preparation
Removing sundries such as stones, garbage, weeds and the like on the surface of the original road, removing accumulated water, and removing similar structures such as well covers and the like on the regeneration road section;
pre-shaping an original road, adjusting a cross slope and a longitudinal slope of the original road, and flattening the original local raised or depressed part to meet the design requirement; large settling or slope variations, beyond the thickness of the regeneration layer, must be handled separately prior to regeneration;
s3, positioning the regeneration train unit
The construction machinery is formed into a train from top to bottom on a construction site according to the sequence of a material adding spreader, a waterwheel, an asphalt truck, a cold recycling machine, a recycled material spreader and a road roller, wherein the waterwheel, the asphalt truck, the cold recycling machine and the recycled material spreader form a recycling unit;
s4, spreading the premixed adding materials
Mixing powdery cement, broken stone aggregate, mineral powder and water to form a premixed additive, and paving the premixed additive on a road surface in advance by using an additive paving machine;
s5, milling and mixing by a cold recycling machine
The cold recycling machine pushes the asphalt truck and the waterwheel to advance on the original road surface, the cold recycling machine mills the original road into recycled aggregate, hot asphalt in the asphalt truck contacts with normal-temperature cold water with accurate supply of the waterwheel to generate foamed asphalt, and the recycled aggregate, the foamed asphalt and the premixed material paved on the original road surface in advance are mixed to form a recycled mixture;
s6, spreading the regeneration mixture
The regeneration mixture is conveyed to a regeneration material paver behind by an airborne conveying belt of the cold regenerator, and the regeneration mixture is continuously, uniformly and uninterruptedly paved on a road surface behind the regeneration mixture by the regeneration material paver;
s7, rolling
According to the difference of road width, wheel width and wheel track of the road roller, making a rolling scheme to ensure that the rolling times of all parts are the same as much as possible, and two to three times of rolling are carried out on two sides of the road surface;
s8 seam processing
The treatment of the longitudinal seam, namely keeping the longitudinal seam wet to facilitate the combination of materials; the position of the longitudinal joint avoids the wheel track position of the slow-moving and heavy-duty vehicle as much as possible;
the transverse joint is processed, and the shutdown phenomenon is reduced as much as possible in the construction process; the strict checking of the machine, in particular the water pipe, exhaust, the gas having to be removed before the liquid reaches the spray bar; the spraying amount of cement slurry or water is checked to avoid the occurrence of transverse excess or deficiency; at a shutdown, before the regeneration unit is constructed again, the whole regeneration unit is retreated by 1.5-2 meters;
s9, health preserving
After the regenerated pavement is rolled and passes the compaction degree inspection, the curing is started immediately, no water is needed to be sprayed during the curing, and the curing time is not less than seven days.
Preferably, the screening result and the grading range are obtained by screening the recycled aggregate milled from the original road and each dry material in the premixed feeding materials, and the blending proportion of the recycled aggregate and each dry material in the premixed feeding materials is calculated as the recycled aggregate: broken stone aggregate: mineral powder: powder cement 88.5:6.0:4.0: 1.5.
Preferably, the optimum water content rate omega of the regeneration mixtureJiaThe water content is calculated according to the field condition, the dry density of each test piece is obtained by adopting a standard compaction test, a water content-density curve is drawn, the water content under the maximum dry density is obtained and is used as the optimal water content omegaJiaGenerally, 6% is less than or equal to omegaJia≤9％。
Preferably, the optimum water content ratio ωJiaThe content was 7%.
Preferably, the consumption of the foamed asphalt is 2.3 percent, the dry splitting strength of the foamed asphalt mixture test piece is 0.79MPa, the splitting strength of the foamed asphalt mixture test piece after being soaked in water for 24 hours is 0.76MPa, and the dry-wet splitting strength ratio under the condition is 96 percent and is far higher than the requirement that the specification is not lower than 75 percent; the freeze-thaw splitting strength ratio is 77 percent, and the technical requirement of the specification of not less than 70 percent is met; the results prove that the foamed asphalt cold recycling mixture has reasonable design in aspects of mixing ratio, asphalt foaming property and the like.
Preferably, the spraying system is used for accurately controlling the water quantity injected into the cold regenerator by the water wagon and the asphalt quantity injected into the cold regenerator by the asphalt wagon, so that the mass of the injected water is 1.5% of that of the asphalt.
Preferably, the water adding amount m of the cold recycling machine corresponding to the dry material of the recycled mixture of unit mass is determined according to the mass of the asphaltMachine for workingCombined with the optimal water content omega of the regenerated mixtureJiaCalculating and determining the water content omega of the premixed and added materialsAdditive for foodFurther determining the water requirement for mixing the premixed and added materials; premixed additive proportioning water content omegaAdditive for foodCan be determined by the following formula calculation;
wherein, ω isAdditive for foodProportioning water content of the premixed additive;
mdry matterThe dry material mass of the regenerated mixture is unit mass;
ωjiaThe optimal water content of the regenerated mixture is obtained;
mmachine for workingAdding water quantity for a cold recycling machine corresponding to the dry materials of the recycled mixture with unit mass;
madditive for foodIs the mass of dry materials (powdery cement, broken stone aggregate and mineral powder) added in the premixed mode in the dry materials of the unit mass of the regeneration mixture.
(III) advantageous effects
The invention provides a construction method for premixing foam asphalt base layer and subbase layer by in-situ cold regeneration. Compared with the prior art, the method has the following beneficial effects:
the method comprises the steps of determining the demand of crushed stone, mineral powder, cement and foamed asphalt according to the quantity of recycled aggregate milled on the original road, calculating and determining the proportioning water content of premixed feeding materials by combining the effective foaming water content of the foamed asphalt and the optimal water content of a recycled mixture, and further determining the mixing water demand of the premixed feeding materials; and pre-mixing the water, the powdery cement, the crushed stone aggregate and the mineral powder which are calculated and determined according to the required amount of the pre-mixed additive to form the pre-mixed additive. The powdery cement is prevented from drifting, the cement, the broken stone aggregate and the mineral powder with the optimal proportion are effectively added, the optimal water content of the recycled mixture and the quality of the foamed asphalt are ensured, and the recycled mixture has high-quality performance indexes.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the application provides a premixed foam asphalt base layer and a subbase layer in-situ cold regeneration construction method, and solves the problem that various additives with optimal proportion cannot be effectively and harmlessly added in the in-situ cold regeneration construction process.
In order to solve the technical problems, the general idea of the embodiment of the application is as follows:
it should be noted that, the current construction methods of foamed asphalt in-situ cold recycling are mainly two. One method is that powdery cement is spread on the damaged road surface uniformly in advance, a regenerating unit generates foamed asphalt by using water and asphalt, the road surface is milled to obtain regenerated aggregate, the powdery cement, the foamed asphalt and the regenerated aggregate are mixed to form a regenerated mixture, and then the mixture is spread on site to repair the road surface. The other is that the foamed asphalt recycling unit utilizes the cement slurry to be led into a cold recycling machine to be mixed with asphalt to generate foamed asphalt, and simultaneously, the pavement is milled to mix the original pavement material with the foamed asphalt to form recycled mixture, and then the recycled mixture is paved on site to repair the pavement.
The first construction method is to spread active substances such as powdery cement on the road surface in advance, cement dust is easily caused by mechanical operation vibration and open wind, additive pollution such as cement dust and the like in the surrounding environment of the construction road can be caused firstly, and the additive proportion in the regenerated mixture is reduced after the additive is lost, so that the construction quality is directly influenced.
The second construction method is that the cement paste and the asphalt generate the foamed asphalt which has certain influence on the quality of the foamed asphalt and is not beneficial to the expansion rate of the foamed asphalt, and meanwhile, the cement paste is easy to change in concentration along with the construction, for example, the cement paste concentration in the early stage is small, the cement paste concentration in the later stage is large during the construction, and the quality of the foamed asphalt is further damaged.
Therefore, in the prior art, the effective addition amount of the additive is difficult to control, or the quality of the foamed asphalt is influenced, so that the performance index of the recycled mixture is not up to the standard.
The method comprises the steps of determining the demand of crushed stone, mineral powder, cement and foamed asphalt according to the quantity of recycled aggregate milled on the original road, calculating and determining the proportioning water content of premixed feeding materials by combining the effective foaming water content of the foamed asphalt and the optimal water content of a recycled mixture, and further determining the mixing water demand of the premixed feeding materials; and pre-mixing the water, the powdery cement, the crushed stone aggregate and the mineral powder which are calculated and determined according to the required amount of the pre-mixed additive to form the pre-mixed additive. The powdery cement is prevented from drifting, the cement, the broken stone aggregate and the mineral powder with the optimal proportion are effectively added, the optimal water content of the recycled mixture and the quality of the foamed asphalt are ensured, and the recycled mixture has high-quality performance indexes.
In addition, the invention adds corresponding broken stone aggregate to the original road pavement material for reinforcement, thereby ensuring the strength requirement of the regenerated road.
In order to better understand the above technical solutions, the above technical solutions will be described in detail through specific embodiments.
Example (b):
the invention provides a construction method for premixing foam asphalt base layer and subbase layer in-situ cold regeneration, which sequentially comprises the following steps:
s1, traffic is sealed
Setting a notice board at each intersection of a regeneration road section one week before preparing an original road surface to remind drivers and pedestrians of closing the time of traffic; when the original road surface is constructed, the traffic is completely closed, and all vehicles are forbidden to pass; in the whole construction and maintenance process, the traffic of the regeneration road section is completely sealed; and a warning board is arranged on the unreproduced road section to remind a driver and pedestrians.
S2, original road preparation
Removing sundries such as stones, garbage and weeds on the surface of an original road (including adjacent lanes and shoulders which do not need to be regenerated), removing accumulated water, and removing similar structures such as well covers and the like on a regenerated road section;
pre-shaping an original road, adjusting a cross slope and a longitudinal slope (including an ultrahigh road or a road arch) of the original road, and flattening the original local bump or depression to meet the design requirement; large settling or slope variations, beyond the thickness of the regeneration layer, must be handled separately prior to regeneration.
S3, positioning the regeneration train unit
And (3) forming the construction machinery into a train from top to bottom according to the sequence of the material adding spreader, the water wheel, the asphalt vehicle, the cold recycling machine, the recycled material spreader and the road roller on a construction site, wherein the water wheel, the asphalt vehicle, the cold recycling machine and the recycled material spreader form a recycling unit.
S4, spreading the premixed adding materials
Mixing the powdery cement, the broken stone aggregate, the mineral powder and the water to form a premixed additive, and paving the premixed additive on the road surface in advance by using an additive paving machine.
Calculating the material usage: and calculating the addition amount of new materials per square meter according to the average density in the regeneration depth of the original road. And calculating the feeding distance of each vehicle according to the mass or volume of each vehicle. The thickness of the added fresh material must be less than the regenerated thickness.
When a new material is added and loaded, the quantity of the materials of each vehicle is controlled to be basically equal. And in the section of the same stock yard for feeding, discharging the filling material from far to near to the spreading machine according to the calculated distance. The discharging distance should be strictly controlled, so that uneven discharging is avoided. And uniformly spreading the new feeding materials on the old road surface, and checking whether the quality of the new feeding materials is uniform or not according to the uniform section of each thousand square meters.
After the premixed adding materials are paved, the surface of the tile should have no blank position and no place where the premixed adding materials are excessively concentrated. The premixing and adding materials are not required to be paved at the whole construction road section at the same time, the premixing and adding materials are required to be uniformly paved within the working width range of the cold recycling machine, and the premixing and adding materials of the other working surface are paved after the working surface with one working width is finished.
S5, milling and mixing by a cold recycling machine
The cold recycling machine pushes the asphalt truck and the waterwheel to advance on the original road surface, the cold recycling machine mills the original road into recycled aggregate, hot asphalt in the asphalt truck contacts with normal-temperature cold water with accurate supply of the waterwheel to generate foamed asphalt, and the recycled aggregate, the foamed asphalt and the premixed material paved on the original road surface in advance are mixed to form a recycled mixture.
The advancing speed of the cold recycling machine is adjusted according to the road surface damage condition and the recycling depth, generally to be 4-8 m/min, so that the small grading fluctuation range of milled materials is ensured.
And the section with serious network fracture adopts a slower speed. And (4) periodically checking whether the regeneration depth is correct or not according to the horizontal control piles arranged on the two sides of the road, if the regeneration depth exceeds the design depth +/-1 cm, finding out the reason and then continuing construction. A special person is required to follow the cold regenerator, the regeneration depth and the water content are checked at any time, and the cold regenerator is matched with an operator of a regeneration unit for adjustment. In the inspection of the regeneration depth in the construction, the adjacent regenerated or original pavement is taken as a standard, steel fibers are penetrated into the soil, the penetration depth is measured, and whether the depth is qualified or not is judged. And (4) checking the two sides of the cold regenerator which are lowered each time, and checking the other road sections for 30-50 m once. Guide wires are fixed at the edges of the working surface to help operators. If multi-tool construction is carried out, attention should be paid to the overlapping width at any time, and the overlapping width is ensured.
4-5 people are arranged behind the cold recycling machine to process sidelines and clean impurities in the mixed materials and excess materials at the initial position of each cutter, so that influences on longitudinal seams, transverse seams, flatness and compactness of recycled materials are prevented. In the construction process, when the grading of the recycled mixture, the recycling depth and the spraying amount of water are in any doubt, the construction must be stopped, and the construction is continued after the problems are solved. The length of each regeneration is required to ensure that the subsequent operation can be normally carried out.
S6 spreading cold recycling mixture
The regenerated mixture is conveyed to a rear regenerated material paver by a material conveying belt carried by the cold regenerator, and a hopper of the regenerated material paver is matched with the discharging speed of the cold regenerator. The speed of the spreading machine is preferably 4-8 m/min. So as to ensure continuous, uniform and uninterrupted paving, and ensure that the height of the regenerated mixture in the distributing chute is kept above the central shaft. The loose paving coefficient of the foamed asphalt regeneration layer is 1.25-1.30.
The local segregation phenomenon is treated in time by a specially-assigned person. And a special person is arranged behind the regeneration unit to carry out quality control, the paving thickness and the water content are checked at any time, and the special person is matched with an operator of the regeneration unit to carry out adjustment.
S7, rolling
According to the difference of road width, wheel width and wheel track of the road roller, a rolling scheme is formulated, the rolling times of all parts are guaranteed to be the same as much as possible, and the two sides of the road surface are pressed for 2-3 times. And a double-steel-wheel vibration road roller is arranged behind the regeneration unit for primary pressing. And during initial compaction, firstly enabling the road roller to closely follow the regeneration unit for static pressure once, compacting by adopting the vibration of the vibration road roller after the static pressure, wherein the compaction times are enough to ensure that the compactness of the bottom 2/3 of the regeneration layer in the thickness range reaches the specified requirement. Each rolling is started from the starting point of the construction section to the edge of the regeneration unit, and the rolling width exceeds the regeneration width.
The working speed of the road roller must not exceed 3 km/h. If the wheel sticking phenomenon occurs when the large-tonnage single-steel-wheel road roller is used for primary pressing, the rubber-wheel road roller is firstly sprayed with water in advance for prepressing and then primary pressing is carried out. After the initial pressure is finished, the double-steel-wheel vibratory roller is used for vibration to carry out re-pressing. Straight lines and flat curve sections without superelevation are overlapped 1/2 wheel widths when the road is rolled from the road shoulder to the road center, and one time is needed when the full width of the road is pressed. Generally, rolling is carried out for 6-8 times. The rolling speed of the road roller is preferably 1.5-1.7 km/h for the first two times, and is preferably 2.0-2.5 km/h for the later time. And finally, performing final pressing for not less than 8 times by using a rubber-tyred roller. If necessary, water can be sprayed for rolling.
S8 seam processing
The treatment of the longitudinal seam, namely keeping the longitudinal seam wet to facilitate the combination of materials; the position of the longitudinal seam avoids the wheel track position of the slow-moving and heavy-duty vehicle as much as possible.
And (4) transverse joint treatment, namely, the halt phenomenon in construction is reduced as much as possible. The machine, and in particular the water pipe, is strictly checked for outgassing, which must be removed before the liquid reaches the spray bar. The cement slurry or water is inspected to avoid lateral excess or deficiency. And (4) at the stop, before the regeneration unit is constructed again, retreating the whole regeneration unit by 1.5-2 meters.
S9, health preserving
After the regenerated pavement is rolled and passes the compaction degree inspection, the curing is started immediately, no water is needed to be sprayed during the curing, and the curing time is not less than seven days. The foamed asphalt is stabilized on the regeneration layer during the curing period.
And after the foamed asphalt cold-recycling asphalt mixture base layer is paved, further evaporating the water in the recycling mixture. The water content in the pavement is detected in time in the curing process, and when the water content of the regeneration base layer is less than or equal to 2 percent, the complete core sample is taken out, so that the curing can be finished in advance.
When the health preserving is carried out under the condition of closed traffic, the natural health preserving is carried out, and measures are generally not needed. When the health preserving is carried out under the condition of open traffic, the regeneration layer can open the traffic after the compaction is completed for at least one day, but the heavy vehicles are strictly limited to pass, the driving speed is controlled within 40km/h, and the vehicles are strictly prohibited from turning around and braking suddenly on the regeneration layer. In order to avoid damage to the surface layer caused by the wheels, slow-breaking emulsified asphalt (diluted to about 30 percent of effective content) is uniformly sprayed on the regeneration layer, and the spraying dosage is 0.05-0.2 kg/square meter after being converted into pure asphalt.
In the method, the screening result and the grading range are obtained by screening the recycled aggregate milled on the original road and each dry material in the premixed feeding material, so that the blending proportion of the recycled aggregate and each dry material in the premixed feeding material is calculated, and in the embodiment, the recycled aggregate is as follows: broken stone aggregate: mineral powder: powder cement 88.5:6.0:4.0: 1.5.
Optimum water content omegaJiaHas obvious influence on the workability and the compaction effect of construction. The addition of water promotes the decomposition of aggregate agglomerates, facilitates the diffusion of asphalt in the mixing process, increases the construction workability, but the addition of excessive water can influence the strength and the compactness of the mixture. Therefore, the optimum water content rate omega of the regeneration mixtureJiaThe water content is calculated according to the field condition, the dry density of each test piece is obtained by adopting a standard compaction test, a water content-density curve is drawn, the water content under the maximum dry density is obtained and is used as the optimal water content omegaJiaGenerally 6% to omegaJia≤9％，ωJiaPreferably 7%.
According to the proportion and the optimal water content of each grade material in the synthetic grading, the foamed asphalt with the three dosage of 2.0 percent, 2.3 percent and 2.6 percent is respectively added to stir the foamed asphalt cold regeneration mixture. Preparing a sample according to a test piece forming and curing method in technical Specification for regenerating asphalt pavements for roads (JTG/T5521-2019), and performing performance test on the sample, wherein the cleavage strength of the foamed asphalt cold-recycling mixture meets the technical requirements that the existing regeneration technical Specification is not less than 0.40MPa (when the foamed asphalt cold-recycling mixture is used for a base layer and a subbase layer) or not less than 0.50MPa (when the foamed asphalt cold-recycling mixture is used for a subbase layer). In addition, the dry-wet splitting strength ratios of the three cold-recycled asphalt mixtures using the foamed asphalt are all more than 90 percent and far higher than the requirement that the specification is not less than 75 percent.
When the consumption of the foamed asphalt is 2.3%, the dry splitting strength of a sample of the foamed asphalt mixture is 0.79MPa, the splitting strength of the sample after soaking in water for 24 hours is 0.76MPa, and the dry-wet splitting strength ratio under the condition is 96%. The results preliminarily verify that the mix proportion of the foamed asphalt cold recycling mixture and the asphalt foaming characteristic are reasonable in design.
And determining the optimal asphalt dosage of the foamed asphalt mixture to be 2.3% by combining engineering experience and integrating the economy of projects and the durability of the cold-recycling mixture. After the subsequent test and inspection, the freeze-thaw splitting strength ratio of the mixture is 77% under the consumption of the foamed asphalt, and the technical requirement that the specification is not less than 70% is met. Thus determining the dosage of the foamed asphalt.
The spraying system is utilized to accurately control the water quantity injected into the cold recycling machine by the water truck and the asphalt quantity injected into the cold recycling machine by the asphalt truck, so that the mass of the injected water is 1.5% of the mass of the asphalt, and the foaming quality of the foamed asphalt is ensured.
Determining the water adding amount m of the cold recycling machine corresponding to the dry materials of the recycled mixture with unit massMachine for workingCombined with the optimal water content omega of the regenerated mixtureJiaCalculating and determining the water content omega of the premixed and added materialsAdditive for foodAnd further determining the water requirement for mixing the premixed charge. Premixed additive proportioning water content omegaAdditive for foodCan be determined by the following formula calculation.
Wherein, ω isAdditive for foodProportioning water content of the premixed additive;
mdry matterThe dry material mass of the regenerated mixture is unit mass;
ωjiaThe optimal water content of the regenerated mixture is obtained;
mmachine for workingAdding water quantity for a cold recycling machine corresponding to the dry materials of the recycled mixture with unit mass;
madditive for foodIs the mass of dry materials (powdery cement, broken stone aggregate and mineral powder) added in the premixed mode in the dry materials of the unit mass of the regeneration mixture.
By the method, the usage amounts of the water, the broken stone aggregate, the mineral powder and the powdery cement of the premixed additive can be respectively calculated; the amount of the foamed asphalt and the water demand of the foamed asphalt; pre-mixing the water, the powdery cement, the crushed stone aggregate and the mineral powder which are calculated and determined according to the required amount of the pre-mixed feeding to form the pre-mixed feeding; the powdery cement is prevented from drifting, the cement, the broken stone aggregate and the mineral powder with the optimal proportion are effectively added, the optimal water content of the recycled mixture and the quality of the foamed asphalt are ensured, and the recycled mixture has high-quality performance indexes.
It should be noted that, the current construction methods of foamed asphalt in-situ cold recycling are mainly two. One method is that powdery cement is spread on the damaged road surface uniformly in advance, a regenerating unit generates foamed asphalt by using water and asphalt, the road surface is milled to obtain regenerated aggregate, the powdery cement, the foamed asphalt and the regenerated aggregate are mixed to form a regenerated mixture, and then the mixture is spread on site to repair the road surface. The other is that the foamed asphalt recycling unit utilizes the cement slurry to be led into a cold recycling machine to be mixed with asphalt to generate foamed asphalt, and simultaneously, the pavement is milled to mix the original pavement material with the foamed asphalt to form recycled mixture, and then the recycled mixture is paved on site to repair the pavement.
The first construction method is to spread active substances such as powdery cement on the road surface in advance, cement dust is easily caused by mechanical operation vibration and open wind, additive pollution such as cement dust and the like in the surrounding environment of the construction road can be caused firstly, and the additive proportion in the regenerated mixture is reduced after the additive is lost, so that the construction quality is directly influenced.
The second construction method is that the cement paste and the asphalt generate the foamed asphalt which has certain influence on the quality of the foamed asphalt and is not beneficial to the expansion rate of the foamed asphalt, and meanwhile, the cement paste is easy to change in concentration along with the construction, for example, the cement paste concentration in the early stage is small, the cement paste concentration in the later stage is large during the construction, and the quality of the foamed asphalt is further damaged.
Therefore, in the prior art, the effective addition amount of the additive is difficult to control, or the quality of the foamed asphalt is influenced, so that the performance index of the recycled mixture is not up to the standard.
In the embodiment of the invention, the water, the powdery cement, the crushed stone aggregate and the mineral powder which are calculated and determined according to the required amount of the premixed feeding material are mixed in advance to form the premixed feeding material. The powdery cement is prevented from drifting, the cement, the broken stone aggregate and the mineral powder with the optimal proportion are effectively added, the optimal water content of the recycled mixture and the quality of the foamed asphalt are ensured, and the recycled mixture has high-quality performance indexes.
In addition, it should be noted that, after the old road pavement material is heavily rolled for many years, the strength of the internal aggregate is slightly reduced, and the particle size of the aggregate is also reduced. In the prior art, when the foam asphalt in-place cold recycling construction technology utilizes an original damaged pavement material, corresponding new aggregates cannot be added for reinforcement aiming at the original road pavement material, and after pavement repair, the embedding, extruding and locking capabilities inside a spreading layer are insufficient due to small particle size of the internal aggregates, so that the overall strength of a recycled road is low.
The embodiment of the invention adds corresponding broken stone aggregate to the original road pavement material for reinforcement, thereby ensuring the strength requirement of the regenerated road.
In summary, compared with the prior art, the invention has the following beneficial effects:
1. according to the embodiment of the invention, the required amount of crushed stone, mineral powder, cement and foamed asphalt is determined according to the amount of the recycled aggregate milled on the original road, the water content of the effective foaming of the foamed asphalt and the optimal water content of the recycled mixture are combined, the proportioning water content of the premixed feeding materials is calculated and determined, and the water requirement for mixing the premixed feeding materials is further determined; and pre-mixing the water, the powdery cement, the crushed stone aggregate and the mineral powder which are calculated and determined according to the required amount of the pre-mixed additive to form the pre-mixed additive. The powdery cement is prevented from drifting, the cement, the broken stone aggregate and the mineral powder with the optimal proportion are effectively added, the optimal water content of the recycled mixture and the quality of the foamed asphalt are ensured, and the recycled mixture has high-quality performance indexes.
2. The embodiment of the invention adds corresponding broken stone aggregate to the original road pavement material for reinforcement, thereby ensuring the strength requirement of the regenerated road.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (6)
1. The construction method for the premixed foam asphalt base layer and the subbase layer through in-situ cold regeneration is characterized by sequentially comprising the following steps of:
s1, traffic is sealed
Setting a notice board at each intersection of a regeneration road section one week before preparing an original road surface to remind drivers and pedestrians of closing the time of traffic; when the original road surface is constructed, the traffic is completely closed, and all vehicles are forbidden to pass; in the whole construction and maintenance process, the traffic of the regeneration road section is completely sealed; a warning board is arranged on the unreproduced road section to remind a driver and pedestrians;
s2, original road preparation
Removing stones, garbage and weeds on the surface of the original road, removing accumulated water and removing well covers on the regeneration road section;
pre-shaping an original road, adjusting a cross slope and a longitudinal slope of the original road, and flattening the original local raised or depressed part to meet the design requirement; large settling or slope variations, beyond the thickness of the regeneration layer, must be handled separately prior to regeneration;
s3, positioning the regeneration train unit
The construction machinery is formed into a train from top to bottom on a construction site according to the sequence of a material adding spreader, a waterwheel, an asphalt truck, a cold recycling machine, a recycled material spreader and a road roller, wherein the waterwheel, the asphalt truck, the cold recycling machine and the recycled material spreader form a recycling unit;
s4, spreading the premixed additive
Mixing powdery cement, broken stone aggregate, mineral powder and water to form a premixed additive, and paving the premixed additive on a road surface in advance by using an additive paving machine;
s5, milling and mixing by a cold recycling machine
The cold recycling machine pushes the asphalt truck and the waterwheel to advance on the original road surface, the cold recycling machine mills the original road into recycled aggregate, hot asphalt in the asphalt truck contacts with normal-temperature cold water with accurate supply of the waterwheel to generate foamed asphalt, and the recycled aggregate, the foamed asphalt and the premixed material paved on the original road surface in advance are mixed to form a recycled mixture;
s6, spreading the regeneration mixture
The regeneration mixture is conveyed to a regeneration material paver behind by an airborne conveying belt of the cold regenerator, and the regeneration mixture is continuously, uniformly and uninterruptedly paved on a road surface behind the regeneration mixture by the regeneration material paver;
s7, rolling
According to the difference of road width, wheel width and wheel track of the road roller, making a rolling scheme to ensure that the rolling times of all parts are the same, and two to three times of rolling are carried out on two sides of the road surface;
s8 seam processing
The treatment of the longitudinal seam, namely keeping the longitudinal seam wet to facilitate the combination of materials; the position of the longitudinal joint avoids the wheel track position of the slow-moving and heavy-duty vehicle;
the transverse joint is treated, namely the shutdown phenomenon is reduced in the construction process; the machine is checked strictly, the gas must be removed before the liquid reaches the spray bar; the spraying amount of cement slurry or water is checked to avoid the occurrence of transverse excess or deficiency; at a shutdown, before the regeneration unit is constructed again, the whole regeneration unit is retreated by 1.5-2 meters;
s9, health preserving
After the rolling of the regenerated pavement is finished and the pavement is qualified through the compactness check, the maintenance is started immediately, no water is required to be sprayed during the maintenance, and the maintenance time is not less than seven days;
determining the water adding amount m of the cold recycling machine corresponding to the dry material of the recycled mixture of unit mass according to the asphalt massMachine for workingCombined with the optimal water content omega of the regenerated mixtureJiaCalculating and determining the water content omega of the premixed and added materialsAdditive for foodAnd then further onDetermining the water requirement for mixing the premixed material; premixed additive proportioning water content omegaAdditive for foodThe determination is calculated by the following formula;
wherein, ω isAdditive for foodProportioning water content of the premixed additive;
mdry matterThe dry material mass of the regenerated mixture is unit mass;
ωjiaThe optimal water content of the regenerated mixture is obtained;
mmachine for workingAdding water quantity for a cold recycling machine corresponding to the dry materials of the recycled mixture with unit mass;
madditive for foodIs the dry mass of the premixed additive in the dry material of the unit mass of the regeneration mixture.
2. The method as claimed in claim 1, wherein the recycled aggregate milled from the road and the dry materials in the premixed charge are screened to obtain a screening result and a grading range, and the blending ratio of the recycled aggregate to the dry materials in the premixed charge is calculated as the recycled aggregate: broken stone aggregate: mineral powder: powder cement 88.5:6.0:4.0: 1.5.
3. The method as claimed in claim 2, wherein the optimum water content of the recycled mixture is ωJiaThe water content is calculated according to the field condition, the dry density of each test piece is obtained by adopting a standard compaction test, a water content-density curve is drawn, the water content under the maximum dry density is obtained and is used as the optimal water content omegaJia，6％≤ωJia≤9％。
4. The method as claimed in claim 3, wherein the optimum water content ω is the optimum water content ωJiaThe content was 7%.
5. The construction method of the premixed foamed asphalt base layer and the base layer for the in-situ cold recycling as claimed in claim 4, wherein the amount of the foamed asphalt is 2.3%, the dry splitting strength of the foamed asphalt mixture test piece is 0.79MPa, the splitting strength after 24h of water immersion is 0.76MPa, and the dry-wet splitting strength ratio under the condition is 96%, which is higher than the requirement that the specification is not lower than 75%; the freeze-thaw splitting strength ratio is 77 percent, and the technical requirement of the specification of not less than 70 percent is met.
6. The construction method of the pre-mixing type foam asphalt base layer and the bottom layer for the cold recycling in situ as claimed in claim 5, wherein the spraying system is used to precisely control the amount of water injected into the cold recycling machine by the waterwheel and the amount of asphalt injected into the cold recycling machine by the asphalt vehicle, so as to satisfy the requirement that the mass of the injected water is 1.5% of the mass of the asphalt.
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| CN113338103B (en) * | 2021-04-28 | 2022-04-15 | 湖南省交建工程集团有限公司 | Premixed foamed asphalt in-situ cold regeneration base layer and bottom surface layer construction method |
| CN113389107A (en) * | 2021-06-28 | 2021-09-14 | 武汉江夏路桥工程总公司 | Milling, mixing, paving and compacting method for synchronous paving and in-situ cold recycling |
| CN113584988A (en) * | 2021-08-25 | 2021-11-02 | 苏州交通工程集团有限公司 | Waste asphalt mixture high-proportion plant-mixed hot recycling pavement and construction method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108570907A (en) * | 2018-04-04 | 2018-09-25 | 北京城建远东建设投资集团有限公司 | The construction method of foamed asphalt cold in place recycling |
| US10246835B1 (en) * | 2017-11-02 | 2019-04-02 | Roadtec, Inc. | Method and apparatus for spreading chips on roadway using foamed asphalt cement |
| CN209891024U (en) * | 2018-12-28 | 2020-01-03 | 吴江市明港道桥工程有限公司 | Asphalt mixture in-situ cooling regeneration equipment |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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-
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10246835B1 (en) * | 2017-11-02 | 2019-04-02 | Roadtec, Inc. | Method and apparatus for spreading chips on roadway using foamed asphalt cement |
| CN108570907A (en) * | 2018-04-04 | 2018-09-25 | 北京城建远东建设投资集团有限公司 | The construction method of foamed asphalt cold in place recycling |
| CN209891024U (en) * | 2018-12-28 | 2020-01-03 | 吴江市明港道桥工程有限公司 | Asphalt mixture in-situ cooling regeneration equipment |
Non-Patent Citations (2)
| Title |
|---|
| 3800CR泡沫沥青就地冷再生技术改进研究与应用;刘鑫等;《施工技术》;20180630;第47卷(第增刊期);第1383-1386页 * |
| 浅谈泡沫沥青就地冷再生技术在河北省的应用;付淑芳等;《公路交通科技》;20111130(第11期);第67-70页 * |
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