CN114775357A - A construction method for the upper layer of steel slag asphalt mixture - Google Patents

Abstract

The invention provides a construction method of an upper surface layer of a steel slag asphalt mixture. The construction method comprises the following steps: preparing construction materials, checking and accepting a middle surface layer, constructing a bonding layer, mixing a steel asphalt mixture, transporting the steel slag asphalt mixture, paving the steel slag asphalt mixture, rolling the steel slag asphalt mixture, setting and processing construction joints, and checking and accepting; the rolling of the steel slag asphalt mixture comprises primary pressing, secondary pressing and final pressing, wherein the rolling speed of the primary pressing and the secondary pressing is 4-5km/h, and the rolling speed of the final pressing is 2-3 km/h. The construction method has the characteristics of simple construction process and high construction efficiency, and simultaneously, the cohesive force and the shear strength of the steel slag asphalt mixture adopted by the upper layer of the invention and the ageing resistance, the wear resistance and the like of the asphalt pavement are improved to a certain extent compared with the common crushed stone mixture, and the service level of the highway can be effectively improved.

Description

A construction method for the upper layer of steel slag asphalt mixture

technical field

The invention belongs to the technical field of road construction, and particularly relates to a construction method for the upper layer of a steel slag asphalt mixture.

Background technique

In recent years, the asphalt concrete surface layer has been widely used in my country's highways due to its advantages of smooth surface, good wear resistance, no joints, construction period and convenient maintenance. However, with the increasing traffic volume, asphalt aging, The cracking of the road surface seriously restricts the safe operation of the road.

As a viscoelastic material, asphalt has low relative molecular weight and wide distribution range, and is highly sensitive to temperature. It becomes soft and sticky at high temperature, brittle and easy to crack at low temperature, and has poor fatigue resistance. To a certain extent, it restricts the development of asphalt. Based on this, it is necessary to add some additive materials to the asphalt to form an asphalt mixture to improve the problems of aging and pavement cracking in the upper layer of the asphalt.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a construction method for the upper layer of the steel slag asphalt mixture, so as to solve the problems of aging and road cracking existing in the asphalt upper layer.

In order to achieve the above object, the present invention provides the following technical solutions:

A construction method for an upper layer of a steel slag asphalt mixture, the construction method comprising the following steps: preparation of construction materials, acceptance of a middle surface layer, construction of a sticky layer, mixing of the steel slag asphalt mixture, transportation of the steel slag asphalt mixture, and steel slag asphalt Paving of mixture, rolling of steel slag asphalt mixture, setting and treatment of construction joints, inspection and acceptance; among them, rolling of steel slag asphalt mixture includes initial pressing, re-pressing and final pressing, and rolling of initial and re-pressing The speed is 4-5km/h, and the final crushing speed is 2-3km/h.

Optionally, the adhesive layer construction steps are as follows:

First, clean the surface of the middle surface layer, and after the surface is dry, spray asphalt ^on the surface.

Optionally, in the mixing step of the steel asphalt mixture, wet mixing is performed first, and then dry mixing is performed, wherein the wet mixing time is 50-55s, and the dry mixing time is 10-15s.

Optionally, in the paving step of the steel slag asphalt mixture, a single machine is used for whole-width paving construction, the paver adopts an automatic leveling method, and a non-contact balance beam method is used to control the elevation and thickness of the asphalt structural layer; The screed is preheated before starting work, the temperature of the preheated screed is between 100°C and 150°C.

Optionally, in the paving step of the steel slag asphalt mixture, the paving speed is 1-3 m/min.

Optionally, in the paving step of the steel slag asphalt mixture, the loose paving coefficient is 1.2-1.3, and the loose paving thickness is 4.8-5.0 cm; during paving, the construction temperature of the asphalt pavement is greater than 10°C.

Optionally, in the rolling step of the steel slag asphalt mixture, staggered wheel rolling is used during rolling, and the overlap between the two rolling wheel tracks is controlled by 25-35 cm.

Optionally, the rolling methods of initial pressing and re-pressing are followed by rolling after the paver, and the number of rolling times is 4-5 times. Wheel track, the number of rolling times is 1.

Optionally, in the construction joint setting and processing steps, before the temperature is not completely lowered after the construction is completed on the day, the end of the paving material is manually removed and aligned with an air pick, so that the transverse joint direction is perpendicular to the paving direction, and the upper and lower layers are The transverse joints between them shall be staggered by at least 1m; the rolling operation at the transverse joints is as follows: firstly, the double-drum road roller is used for transverse rolling. During the rolling, the road roller is on the compacted mixture layer and extends into the new pavement. The width of the layer is 12-18cm, and then move 15-20cm to the new laying mixture every time it is pressed, until it is all on the new laying layer, and then carry out longitudinal rolling.

Optionally, the construction method further includes road surface anti-pollution treatment, traffic control and open traffic, wherein, in the road surface anti-pollution treatment step, concrete is used to harden the upper ramp, colored strips are laid on the ramp, and waterwheels are arranged to The tires of the vehicle are washed, and the vehicles entering and exiting the uphill slope are wrapped with oil cloth; the traffic control and traffic opening steps are as follows: the completed asphalt structure layer is closed for traffic, and all overloaded vehicles are prohibited from the road that has been constructed. Traffic can be opened only when the road surface temperature is lower than 50°C.

Beneficial effects:

The construction method for the upper layer of the steel slag asphalt mixture of the present invention has the characteristics of simple construction process and high construction efficiency. Compared with ordinary crushed stone mixture, its wear resistance and wear resistance are improved to a certain extent, which can effectively improve the service level of highways.

Description of drawings

The accompanying drawings forming a part of the present invention are used to provide further understanding of the present invention, and the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute an improper limitation of the present invention. in:

1 is a process flow diagram of a construction method for an upper layer of a steel slag asphalt mixture according to an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art fall within the protection scope of the present invention.

The present invention will be described in detail below with reference to the embodiments. It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

The invention proposes a construction method for the upper layer of the steel slag asphalt mixture, aiming at the problems of aging, road cracking and the like existing in the asphalt upper layer.

The application of steel slag in highway engineering can not only reduce the demand for stone materials for highway construction and maintenance, reduce the mining of natural stone, and improve the ecological environment damage caused by large-scale quarrying, but also has a low crushing value and rough surface. Characteristics, good adhesion with asphalt, cohesive force, shear strength of steel slag asphalt mixture, and anti-aging and wear resistance of asphalt pavement are all improved to a certain extent compared with ordinary crushed stone mixture, which can effectively improve highways. service level.

The construction of the test section is carried out before the construction of the present invention, and the construction of the test section is divided into two stages of trial mixing and trial paving of the steel slag asphalt mixture. Among them, according to the principle of matching the construction capabilities of various machinery, the reasonable type and quantity of construction machinery are determined. The operation mode of the mixer, such as feeding speed, mixing quantity, mixing time and mixing temperature, etc., is determined by trial mixing; at the same time, the mixing ratio design of the steel slag asphalt mixture and the material index of the asphalt mixture are verified. Determine the mix ratio of steel slag and mineral material and the ratio of oil and stone for formal production. Determine the operation mode of the paver, the paving temperature, the paving speed, the method and strength of the initial vibration and compaction, the automatic leveling method, etc. through the trial paving; determine the selection, combination, rolling sequence, rolling temperature, Rolling speed and rolling times; determine the appropriate loose paving coefficient; determine the mineral material gap ratio, porosity, asphalt saturation, gross bulk density, stability and flow value by Marshall test. Determine whether the rated normal production capacity of the mixing plant matches the construction progress on site. According to the construction of the test section, various technical parameters can be determined to guide the large-scale construction.

As shown in the schematic diagram of the construction process shown in Figure 1, the construction method of the present invention comprises the following steps: preparation of construction materials, acceptance of the middle surface layer, construction of the adhesive layer, mixing of the steel-asphalt mixture, transportation of the steel-slag-asphalt mixture, and mixing of the steel-slag-asphalt mixture Paving of materials, rolling of steel slag asphalt mixture, setting and treatment of construction joints, inspection and acceptance, anti-pollution treatment of pavement, traffic control and open traffic, the following describes each construction step in detail.

The present invention conducts construction preparations before construction, mainly preparing steel slag asphalt materials and the acceptance of the mid-surface layer, wherein the material preparations include: (1) Asphalt, the anti-slip and wear layer of the asphalt pavement adopts SBS modified emulsified asphalt. The material properties of modified emulsified asphalt are tested, and its performance indicators must meet the requirements of Table 1.

Table 1 Quality requirements of SBS modified emulsified asphalt

It should be noted that during the construction process, regular samples are taken to check the product quality, and SBS modified emulsified asphalt that is found to be segregated and other quality does not meet the requirements shall not be used.

(2) Steel slag coarse aggregate, steel slag coarse aggregate should be clean, dry and free of impurities; the surface should be as dense as possible, with a few honeycomb pores allowed. The content of free calcium oxide in the steel slag coarse aggregate used in the steel slag asphalt mixture should not exceed 3%; the water swelling rate of the steel slag coarse aggregate used in the steel slag asphalt mixture should not exceed 1.8%. The specifications of the steel slag coarse aggregate are shown in Table 2.

Table 2 Specifications of steel slag coarse aggregate

The content of particles below 0.075mm in the steel slag coarse aggregate water washing method is not more than 2%, and the quality and technical indicators are shown in Table 3.

Table 3 Quality and technical indicators of steel slag coarse aggregate

(3) Fine aggregate, using 0-3mm machine-made sand, clean and dry, and its quality meets the technical requirements in Table 4 and Table 5 after testing.

Table 4 Quality and technical requirements for fine aggregates

project unit Technical indicators Measured value Apparent relative density, not less than t/m³ 2.50 2.678 The firmness (>0.3mm part) is not more than % 12 4 Sand equivalent not less than % 60 64 Angularity (flow time), not less than s 30 33.1

Table 5 Specifications of fine aggregate for steel slag asphalt mixture

(4) The filler is made of ore powder obtained by grinding limestone. The ore powder is dry and clean, and its quality meets the technical requirements in Table 6.

Table 6 Quality and technical requirements of filler mineral powder

In order to improve the water damage resistance of the asphalt mixture, 1.3±0.3% of the total weight of the mixture is added with quicklime powder or cement, and the recycled powder shall not be used as a filler instead of the mineral powder.

(5) Fiber stabilizer, the fiber stabilizer used in the asphalt mixture is loose flocculent lignin fibers, the lignin fibers are made from coniferous wood as raw materials, and the amount of lignocellulose added is 10% of the quality of the asphalt mixture 0.3%, its quality technical requirements meet the technical requirements in Table 7.

Table 7 Technical requirements for lignin floc fibers

Pilot projects skills requirement Measured value Fiber length not greater than 6mm 5.2 Ash content (%) 18±5 no volatiles 20.5 pH value 7.5±1.0 6.9 The oil absorption rate is not less than 5 times the mass of fiber 8.9 Moisture content (%) ≤5 (calculated by mass) 2.4

The steel slag asphalt mixture should meet the technical standards in Table 8 in Marshall design, mixture water stability design, mixture high and low temperature stability inspection and construction performance inspection.

Table 8 Technical standards for steel slag asphalt mixture

Test index unit Asphalt steel slag mixture Nominal maximum particle size mm 13.2 Number of compactions (double-sided) Second-rate 75 void ratio vv % 3.0-4.0 Mineral material gap ratio VMA, not less than % 16 Saturation VFA % 75-85 stability, not less than kN 6 flow value 0.1mm -- Residual stability, not less than % 85 Coarse aggregate gap ratio VCA % ≯VCADRC Freeze-thaw splitting strength ratio, not less than % 80 Dynamic stability, not less than times/mm 4000 Schellenberg leakage, not greater than % 0.1 Fort Kentucky scatters, no larger than % 15

The volume expansion rate of the steel slag asphalt mixture sample does not exceed 1.5%. If it exceeds, the steel slag needs to be aged until it meets the requirements before it can be used.

The target ratio of steel slag asphalt mixture is shown in Table 9. In addition, the optimal asphalt content is 5.5%, the content of external fiber is 0.3%, the void ratio is 3.5%, the gross volume relative density is 2.891, and the theoretical maximum relative density is 2.997. .

Table 9 Target mix ratio of upper layer of steel slag asphalt mixture

raw materials Steel slag 10-15mm Steel slag 5-10mm Machine-made sand 0-3mm Mineral powder percentage(%) 37 40 13 10

Further, for the batch mixer, the material that enters the hot silo after secondary screening is sampled for screening, and the material ratio of each hot silo and the proportion of mineral powder used are determined, so that the synthetic gradation of mineral materials is close to the target. Mixing ratio for use in mixer control room. At the same time, select the appropriate size and installation angle of the vibrating screen, so that the feeding of each hot silo is generally balanced. Take the optimum asphalt content of the target mix ratio for Marshall test and trial mix, and comprehensively determine the production mix ratio through indoor tests and sampling tests from the mixer, as shown in Table 10. In addition, the optimal asphalt content is 5.34%, and the content of external fiber is 5.34%. It is 0.3%, the porosity is 3.5%, the relative density of gross volume is 2.892, and the theoretical maximum relative density is 2.998.

Table 10 Production mix ratio of steel slag asphalt mixture

raw materials Steel slag 11-18mm Steel slag 6-11mm Machine-made sand 0-3mm Mineral powder percentage(%) 37 41 12.5 9.5

In the specific embodiment of the present invention, according to the design and specification requirements, various technical indicators such as mid-surface layer compaction, longitudinal elevation, flatness, transverse slope, and water seepage coefficient are checked item by item, and the holes left by the drill core are detected. Fill and compact with the same material in layers in advance, and the inspection results are qualified.

In the specific embodiment of the present invention, the construction steps of the sticky layer are as follows: firstly, the surface of the middle surface layer is cleaned and rinsed, and after the surface is dried, an intelligent asphalt distributor is used to distribute the asphalt on the surface, and the asphalt is SBS modified emulsified asphalt , the spraying amount is 0.4-0.6kg/m ² (such as 0.4kg/m ² , 0.5kg/m ² , 0.6kg/m ² and any interval value between any two end points). It should be noted that the inspection and acceptance shall be carried out after the surface of the middle surface layer is dry, and the sticky layer can be sprinkled only after the acceptance is passed.

When spraying, the vehicle speed and spraying amount should be kept stable. The asphalt sprayer should spray evenly in the entire width. Manual brushing should be done with a brush on the side of the curb and other parts that are not easy to spray.

When the temperature is lower than 10℃ or when the road surface is wet, the sticky layer asphalt should not be spread; the sticky layer oil should be spread on the same day. Infected.

It should be noted that if the protection of the curb stones is not in place before the sticky layer is sprayed, some curb stones will be polluted. For this reason, the side baffle of the sprinkler head of the asphalt sprayer should be lowered first to prevent the curb stones from being sprayed to the side, followed by strengthening. Protective measures, cover and wrap the curb with plastic sheeting before spraying.

In the specific embodiment of the present invention, in the mixing step of the steel asphalt mixture, HQLBQ4000 type mixing equipment is selected, and its rated production capacity is 320t/h. During the production of steel slag asphalt mixture, the actual production efficiency shall not be greater than 50% of the maximum production efficiency determined by the mixing station. Before loading, cut the pile at the vertical height in advance to reduce the coarse aggregate slipping and segregation when the loader shovels the material at the bottom.

In the mixing step of the steel asphalt mixture, wet mixing is carried out first, and then dry mixing is carried out, wherein the wet mixing time is 50-55s (such as 50s, 51s, 52s, 53s, 54s, 55s and any value between the two ends. Any interval value), the dry mixing time is 10-15s (such as 10s, 11s, 12s, 13s, 14s, 15s and any interval value between any two end points). Optionally, the mixing time of each pot is set to 70s, wherein the wet mixing time is 55s and the dry mixing time is 15s. The steel slag asphalt mixture should be mixed evenly, and the ore particles used should be completely covered with the asphalt mixture, without any white material, no segregation and agglomeration of coarse and fine materials.

In the transportation of steel slag asphalt mixture, the transport vehicle must be cleaned before each use. In order to prevent the asphalt mixture from sticking to the carriage board, the inside of the carriage is evenly coated with a vegetable oil-based release agent. The digital display plug-in thermocouple thermometer is used to detect (1 vehicle, 1 inspection) the delivery temperature of the asphalt mixture and the temperature delivered to the site, and the insertion depth is greater than 150mm. There is a special detection hole in the middle of the side of the material transporter, and the hole is about 300mm from the bottom of the carriage.

When the mixer discharges the material to the transport vehicle, in order to reduce the segregation of the mixture, the distance from the discharge port to the carriage should be shortened as much as possible, which can be selected as 50cm. Further, fully enclosed thermal insulation measures are adopted around the material transporter, and measures for thermal insulation, rain protection and pollution prevention are adopted covering tarpaulins and quilts on the top.

Make sure that the transport capacity of the asphalt mixture transporter is more than the mixing capacity and paving speed. There are at least 7 transporters waiting for unloading in front of the paver, so that the paver can pave continuously, evenly and uninterruptedly. After each truck arrives at the site, the temperature of the mixture is measured. If the temperature is lower than the paving temperature, the mixture is treated as waste, and the agglomerated or rained mixture is also treated as waste.

It should be noted that during the continuous paving process, the material transporter should stop at 10-30cm in front of the paver (such as 10cm, 20cm, 30cm and the interval value between any two end points), and must not hit the paver. During the unloading process, the transporter is in neutral gear and is pushed forward by the paver to ensure the smoothness of the pavement.

Further, high-pressure water guns are regularly used to wash the chassis of transport vehicles to avoid incomplete cleaning of the chassis of individual transport vehicles and pollution caused by soil falling.

In the paving step of the steel slag asphalt mixture, Zhongda DT2360 paver is used for construction, the paving width is 18.75m, and the single machine is used for the whole-width paving construction. The paver adopts the automatic leveling method and the non-contact balance beam method. Control the elevation and thickness of the asphalt structural layer, and adjust the relative height difference according to the thickness of the structural layer.

The screed is preheated before the paver starts to work, and the preheated screed temperature is between 100°C and 150°C. The paving of the steel slag asphalt mixture is carried out slowly, uniformly and continuously, and the paving process shall not be arbitrarily changed or paused in the middle. min and the interval value between any two endpoints).

In the paving step of steel slag asphalt mixture, the loose paving coefficient is 1.2-1.3 (such as 1.2, 1.3 and any interval value between any two end points), and the loose paving thickness is 4.8-5.0cm (such as 4.8cm, 4.9cm) , 5.0cm and any interval value between any two end points); preferably, during construction, the loose lay coefficient is 1.2, and the loose lay thickness is 4.8cm. When paving, the construction temperature of the asphalt pavement is higher than 10℃, and the construction is in the process of continuous heating. When the temperature is lower than 10℃, the asphalt pavement shall not be paved.

Adjust the paver to the best working state, adjust the screw conveyor and the double material level device, and make the opening of the material door, the speed of the chain plate feeder and the speed of the screw distributor match. The surface of the mixture in the screw conveyor is preferably higher than 2/3 of the screw conveyor (that is, the mixture should be kept above the conveying rotation axis), so that the height of the mixture in front of the baffle of the screed remains consistent within the full width. Avoid segregation in the paving layer.

It should be noted that the personnel on the paving face move frequently, and no technical personnel are arranged to fill the pits. The subsequent large-scale construction reduces the movement of operators on the face, and arranges personnel to reshape and replenish materials.

In the rolling of steel slag asphalt mixture, the road roller sprays water on the laid color strip cloth in advance to eliminate the dust and rust on the steel wheel before starting the rolling. When rolling, the road roller is rolled at a uniform speed. During the rolling process, it is followed by slow pressing, first low and then high, high frequency and low amplitude, and uniform speed and less water; during rolling, staggered wheel rolling is used, and the gap between the two rolling wheel tracks is Control according to the overlap of 25-35cm (such as 25cm, 28cm, 30cm, 32cm, 35cm and any interval value between any two end points), preferably, when rolling, the two rolling tracks are overlapped by 30cm. control.

The rolling compaction of steel slag asphalt mixture includes initial compaction, re compaction and final compaction, and the rolling speed of initial compaction and re compaction is 4-5km/h (such as 4km/h, 5km/h and the interval between any two end points) value), the final rolling speed is 2-3km/h (such as 2km/h, 3km/h and the interval value between any two end points). Optionally, five PK6200 double-drum rollers (14 tons) and one small vibratory roller (3.5t) are used as the rolling equipment, and two kinds of rolling combinations are used. The specific rolling process is shown in Table 11 and Table 12. , among which, the rolling method and the specific rolling times during the construction process can be determined according to the results of the test section.

Table 11 Combination method one of rolling

Table 12 Rolling Combination Mode 2

It should be noted that when rolling, the rolling machine should follow the paver for rolling, and the rolling machine should be stopped in a step-like manner when it is turned back. Rolling rolls from outside to inside, from low to high. The vibratory roller should start first and then start vibrating, and stop vibrating first and then stop.

Further, small vibratory rollers are used to supplement the rolling of the road edge. In order to ensure the compaction of the edge, a 14t double-drum roller is vibrated and compacted along the edge of the curb. The construction temperature of the steel slag asphalt mixture at each stage is shown in Table 13.

Table 13 Construction temperature of hot mix asphalt

In the setting and processing steps of construction joints, due to the interruption of work or the end of the work of the day, the end of the paving material has cooled, and a horizontal joint should be made. Before the temperature is completely lowered after the construction is completed on the same day, the end of the paving material is manually removed and aligned with an air pick, so that the transverse joint direction is perpendicular to the paving direction, and the use of miter joints is strictly prohibited.

Further, the horizontal joints between the upper and lower layers should be staggered by at least 1m. Before the next paving, apply an appropriate amount of sticky asphalt on the vertical edge of the end, and adjust the height of the slab to leave a reserve for rolling.

First, use a double-drum road roller for lateral rolling. When rolling, the road roller is on the compacted mixture layer, and the width of the new layer is 12-18cm (such as 12cm, 14cm, 16cm, 18cm and any point value at both ends). Any interval value between), preferably, when rolling, the width of the road roller extending into the new layer is 15cm. Then move 15-20cm (such as 15cm, 16cm, 17cm, 18cm, 19cm, 20cm and any interval value between any two end points) to the newly laid mixture every time it is pressed, until it is all on the new layer, and then proceed Rolled vertically. When the transverse joint is rolled, the forward static pressure will vibrate backward, so as to avoid the deviation of the flatness of the joint caused by the depression of the joint caused by the forward vibration.

In the inspection and acceptance step, it is mainly to detect the Songpu coefficient, flatness and compaction. Among them, the loose paving coefficient is measured according to the frequency of a section of 20 meters in the test section, and each section is measured at 4 points, before and after paving. With the height after forming, then calculate the loose paving coefficient. The test section was paved with a loose paving coefficient of 1.22. The measured average loose paving thickness was 4.9 cm, and the average compaction thickness was 4.1 cm. The calculated loose paving coefficient was 1.2, and the acceptance was qualified. During the construction process, the flatness of the joints and the joints of the structures must be checked at any time with a 6m ruler, and the unqualified places should be repaired in time. The smoothness of normal road sections is measured by a continuous smoothness meter. The on-site compaction degree of the upper layer is controlled by the dual indicators of void ratio and compaction degree, and the compaction degree is required to be greater than 98%. At the same time, according to the requirements of the site extreme void ratio of 3.5-6.5% and the average value of 4-6% as the on-site compaction control index, the compaction degree of the maximum theoretical density shall not be less than 94%, and the water permeability coefficient shall not be greater than 80ml/min. The core-drilling method is used to test the compaction of the asphalt mixture.

In the anti-pollution treatment of the road surface, concrete is used to harden the upper slope, and colored strips are laid on the slope. All vehicles entering and exiting the uphill slope are wrapped with tarpaulins to avoid the pollution of the road surface caused by vehicle oil leakage.

The specific steps for traffic control and traffic opening are to close traffic on the completed asphalt structure layer, prohibit all overloaded vehicles from passing on the pavement that has been constructed, and open traffic only when the road surface temperature is lower than 50°C.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. a construction method of steel slag asphalt mixture upper layer, is characterized in that, described construction method comprises the following steps: construction material preparation, middle surface layer acceptance, sticky layer construction, mixing of steel slag asphalt mixture, steel slag asphalt mixing Transportation of materials, paving of steel slag asphalt mixture, rolling of steel slag asphalt mixture, setting and treatment of construction joints, inspection and acceptance; among which, The rolling compaction of steel slag asphalt mixture includes initial compaction, re compaction and final compaction. 2. the construction method of the upper layer of the steel slag asphalt mixture as claimed in claim 1, is characterized in that, the construction step of sticky layer is specifically: first, the surface of the middle surface is cleaned, and after the surface is dried, the surface is sprayed with asphalt , the asphalt is SBS modified emulsified asphalt, and the spreading amount is 0.4-0.6kg/m ² . 3. the construction method of the upper layer of steel slag asphalt mixture as claimed in claim 1, is characterized in that, in the mixing step of steel asphalt mixture, first carry out wet mixing, then carry out dry mixing, and wherein the time of wet mixing is 50-55s, dry mixing time is 10-15s. 4. the construction method of the upper layer of steel slag asphalt mixture as claimed in claim 1, it is characterized in that, in the paving step of steel slag asphalt mixture, adopt single-machine whole-width paving construction, paver adopts automatic leveling method, adopts Control the elevation and thickness of the asphalt structural layer by means of non-contact balance beams; The screed is preheated before the paver starts to work, and the preheated screed temperature is between 100°C and 150°C. 5 . The construction method for the upper layer of the steel slag asphalt mixture according to claim 4 , wherein, in the paving step of the steel slag asphalt mixture, the paving speed is 1-3 m/min. 6 . 6. The construction method of the upper layer of the steel slag asphalt mixture as claimed in claim 4, characterized in that, in the paving step of the steel slag asphalt mixture, the loose paving coefficient is 1.2-1.3, and the loose paving thickness is 4.8-5.0 cm; When paving, the construction temperature of asphalt pavement is greater than 10 ℃. 7. the construction method of the upper layer of steel slag asphalt mixture as claimed in claim 1, is characterized in that, in the rolling step of steel slag asphalt mixture, adopts staggered wheel rolling during rolling, between two rolling wheel tracks Control according to the overlap of 25-35cm. 8. the construction method of the upper layer of steel slag asphalt mixture as claimed in claim 7, it is characterized in that, the rolling method of initial pressure and recompression is to carry out rolling after the paver, and the number of times of rolling is average. For 4-5 times, the final rolling method is static pressing and finishing until the wheel track is eliminated, and the number of rolling times is 1. 9. The construction method of the upper layer of steel slag asphalt mixture as claimed in claim 1, it is characterized in that, in the construction joint setting and processing step, before the temperature is not completely lowered after the construction is completed on the same day, the artificial use of air picks is used for the construction of the paving material. The ends are planed and aligned so that the transverse joint direction is perpendicular to the paving direction, and the transverse joints between the upper and lower layers are staggered by at least 1m; The rolling operation at the transverse joint is as follows: first, use a double-drum road roller to perform transverse rolling. When rolling, the road roller is on the compacted mixture layer, and the width of the new layer is 12-18cm. Press it again and move 15-20cm to the new layer until it is all on the new layer, and then roll it longitudinally. 10. The construction method for the upper layer of steel slag asphalt mixture according to any one of claims 1 to 9, wherein the construction method further comprises road surface anti-pollution treatment, traffic control and open traffic, wherein, In the anti-pollution treatment of the road surface, concrete is used to harden the ramp, and colored strips are laid on the ramp, and water trucks are arranged to wash the tires of the vehicle. The specific steps for traffic control and traffic opening are to close traffic on the completed asphalt structure layer, prohibit all overloaded vehicles from passing on the pavement that has been constructed, and open traffic only when the road surface temperature is lower than 50°C.

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