What are the asphalt pavement diseases caused by water stability?

1. subgrade engineering quality supervision

The cross section of a general road consists of the following parts:

surface

Upper layer-usually fine-grained asphalt concrete, 3 ~ 5 cm thick, and the maximum particle size of aggregate is10 ~15 mm.

B The bottom layer is generally medium-grained asphalt concrete, with a thickness of 5 ~ 7 cm and a maximum aggregate diameter of 20 ~ 25 mm 。

Road layer

A (upper) surface course-generally cement stabilized macadam or lime-fly ash stabilized macadam, with a thickness of not less than 15 ~ 20 cm.

B subbase-generally lime-fly ash stabilized macadam or calcareous soil, the thickness is not less than 15 ~ 20cm.

roadbed

Roadbed -0 ~ 30cm

Get off the road bed -30 ~ 80 cm

B embankment

Subgrade-80 ~150cm

Get off the road bed -> 150 cm

The basic requirement of subgrade engineering quality is 1. 1

1. 1. 1 should have sufficient strength, because the subgrade must bear all the live loads from the pavement and all the dead loads of the subgrade and its upper part, which requires that the subgrade must have sufficient strength.

1. 1.2 should have sufficient water stability. Under the action of atmospheric precipitation, surface water and groundwater, the shear strength of subgrade is often reduced due to poor water stability, which leads to excessive displacement of slip surface and subgrade, which makes the road gene unstable and damaged. Therefore, the subgrade must have sufficient water stability.

1. 1.3 should have sufficient freezing stability. In areas affected by freezing, subgrade often appears peripheral freezing state, especially in the case of sufficient ground water supply and high groundwater level, or in the case of poor anti-seepage quality of pavement in winter and rainwater can penetrate into subgrade, subgrade will have serious frost heaving diseases, which will reduce subgrade strength and lead to long-term expansion cracks. Therefore, for the subgrade in seasonally frozen areas,

The above requirements are particularly important for subgrade (i.e. the upper subgrade within 0-30cm below the subgrade surface and the lower subgrade within 30-80cm). Therefore, the subgrade is the foundation of the pavement and bears all the loads from the pavement.

1.2 supervision points in preparation stage before subgrade construction

1.2. 1 The supervision engineer shall require the contractor to prepare a feasible "construction organization design" before subgrade construction, and carefully examine and approve it.

1.2.2 The supervision engineer shall participate in or require the contractor to carry out on-site measurement of the given measurement results before the commencement of construction, including the measurement of conductor and centerline, the measurement of leveling points and the measurement and drawing of additional cross sections. Before measurement, the measuring instruments used should be calibrated and corrected. After the contractor's survey results are reported to the supervision engineer for approval, relevant boundary markers and positions (filling the toe of subgrade slope) shall be installed according to the drawing requirements.

1.2.3 the supervision engineer shall require the contractor to take representative soil samples from the fillers necessary for excavation and filling as shown in the drawings, and conduct the following tests under the witness of the supervision engineer, and the contractor shall report the test results to the supervision engineer in writing.

Liquid limit, plastic limit, plastic index and natural consistency;

B particle index;

C density and relative density;

Density and relative density;

E. soil compactness and soil strength (CBR value)

1.2.4 The contractor shall choose the compaction degree detection method that satisfies the supervision engineer. If the nuclear instrument method is adopted, the contractor shall calibrate the nuclear instrument method, and make a comparative test between the sand filling method and the nuclear instrument method to determine its correlation. If sand filling method is adopted, standard sand should be calibrated.

1.2.5 The supervision engineer shall require the contractor to remove all rubbish, trees, crops and turf, plant roots and humus at least/kloc-0 ~ 30cm below the original ground of the site, level it with a grader, and compact it with a roller before filling, so that the compactness can meet the quality inspection standards.

1.2.6 The contractor shall demolish the original old structures (such as houses, bridges, sidewalks, graves, etc.). ) within the scope of subgrade land use according to the requirements of drawings, and remove the waste from the site.

1.2.7 the supervision engineer shall require the contractor to backfill and tamp the original or excavated holes within the scope of subgrade land by layers as required.

1.2.8 After the site is cleared, dismantled, backfilled and compacted (the compaction degree should meet the quality inspection standard of compaction before filling), the contractor is required to retest the cross section, and the construction of the next working procedure can only be carried out after on-site inspection and acceptance by the supervision engineer.

1.3 Key points of subgrade excavation supervision

Excavation can only be carried out after the contractor has made the necessary preparations mentioned above and accepted by the supervision engineer. Secondly, as long as the excavated earthwork can meet the filling requirements, it should be used as much as possible with the consent of the supervision engineer; Thirdly, subgrade drainage facilities should be well done, and subgrade drainage should always be smooth, so as not to affect the construction or cause damage to the project.

1.3. 1 Earthwork excavation shall be carried out layer by layer from top to bottom. During excavation, the stability of the slope shall not be damaged (the slope shall be laid according to the design requirements 1: 1), and indiscriminate excavation, over-excavation and under-excavation shall not be allowed.

1.3.2. When the earth material on the top surface of excavated subgrade is not suitable for subgrade, the earth material meeting the quality requirements shall be removed and replaced.

1.3.3 When the depth below the top surface of excavated subgrade is 30cm, or the depth of soil replacement below the top surface of excavated subgrade exceeds 30cm, the compaction degree shall not be less than 90% of the design value (93% of subgrade, 90% of upper embankment and 90% of lower embankment).

1.3.4 When the soil water content on the top surface of embankment subgrade is too large, the supervision engineer shall order the contractor to loosen soil, dry in the sun or take other technical measures for treatment.

1.4 Key points of subgrade filling supervision

First of all, under the witness of the supervision engineer, take soil samples every 5000m3 of filling or in the soil replacement section, and conduct geotechnical tests on the soil samples to obtain basic test data for future use; Secondly, the test section with paving length not less than 100m (full subgrade) shall be compacted at the filling site. After the test, determine the loose laying thickness, water content, compaction machinery type, the best combination mode, rolling times, rolling speed, working procedure, etc. The compaction degree of the filler shall be recorded until the field compaction test makes the filler reach the specified compaction degree. If the compaction degree of the test meets the quality inspection standard, this section can be used as a part of subgrade, otherwise it should be dug out and tested again.

1.4. 1 Before the formal construction of the fill subgrade, the appropriate filler should be selected first, and the minimum strength (CBR value) of the field geotechnical test should meet the specification requirements.

1.4.2 When filling subgrade (embankment, cutting and embankment foundation), it shall be filled in layers, compacted layer by layer and inspected layer by layer. Its compactness should meet the requirements of design drawings (top-down 93%, 90%, 90%) or specifications; The detection frequency is 8 points per 2000 ㎡, and the detection of less than 200㎡ cannot be less than 2 points.

1.4.3 The filling operation shall be paved in parallel by layers, and the loose paving thickness shall be strictly controlled to ensure its compactness.

1.4.4 When the thickness of subgrade fill is greater than 80cm, the original surface should be loosened by 30cm, leveled and compacted, and its compactness should meet the design or specification requirements.

1.4.5 When filling to the last layer of subgrade top surface, the minimum compaction thickness is 8cm.

1.4.6 When paving in layers, the width of each layer should exceed the designed width of embankment by 30 ~ 50 cm on each side, so as to ensure sufficient compactness of the edge of the embankment after trimming the embankment slope.

1.4.7 When the natural transverse slope or longitudinal slope of the ground is steeper than 1: 5 (according to the specification, the longitudinal slope is steeper than 12%), the original ground should be dug into steps, the width of which should meet the needs of paving and compacting machinery, and should not be less than 1m, and the top of the steps should be 2% ~ 4%.

1.4.8 When the surface soil moisture content is too high, the method of scarifying and airing can be adopted, or with the consent of the supervision engineer, the soil can be changed or improved with low-dose lime, and the soil can be compacted to the specified degree of compaction under the optimal water content condition.

1.4.9 subgrade treatment of special sections

In subgrade construction, we often encounter some special sections, such as fish ponds, lotus ponds, Tang Wei pits and paddy fields or low-lying wet soil sections. Some special measures should be taken to deal with these parts.

1.4.9. 1 When encountering a large pit and pond, firstly, drain water, remove attachments and silt, then throw flaky with appropriate thickness, fill the flaky with materials with good strength and water permeability, such as natural graded macadam, and then fill subgrade soil according to normal conditions. If it is difficult to fill flaky and gravel, you can also choose to backfill the building rubble and fill it on its surface. Fill subgrade soil normally. However, the strength of broken bricks is low, and it is easy to be pulverized after long-term use, especially after several times of ice melting, which affects the strength of subgrade. In the embankment treated with broken bricks, it is necessary to ensure that the soil that meets the requirements of subgrade is filled within 30 ~ 50 cm from the top surface of subgrade to the bottom surface of subgrade (it is not allowed to fill broken bricks directly to the top surface of subgrade), so as to ensure the stability of pavement subgrade and improve the smoothness of subgrade surface.

1.4.9.2 Too wet or too soft embankment foundation, if the wet soil is not deep, it may be considered to replace it with dry soil or natural macadam after excavation, and tamp it in layers to reach the standard; If the over-wet soil is deep, the upper over-wet soil can also be raked flat, mixed with a proper amount of quicklime powder, and compacted until its layer thickness can reach the specified degree of compaction, making it a stabilized soil reinforcement layer; Or mixed with 10% ~ 14% quicklime, and compacted after repeated stirring and air drying. What measures should be taken depends on the situation.

1.4. 10 When widening the old subgrade, it should be excavated vertically along the edge of the old road and turned into inward inclined steps.

1.4.1/When two adjacent sections are not constructed at the same time, the first section shall be filled with steps in layers according to the gradient of 1: 1; If construction is carried out at the same time, it shall be overlapped by layers, and the overlapping length shall be not less than 2m.

1.4. 12 The principle of light before heavy, static before vibration should be followed in real-time subgrade filling.

1.4. 13 When filling subgrade, the thickness, width, transverse slope, compactness and smoothness of each layer should be well controlled. Especially on the top surface of subgrade, the above detection values and deflection tests should be strictly required to meet the requirements. Otherwise, we should find out the reason and deal with it.

2. Quality supervision of pavement base engineering

2. 1.65438+

2. 1.2 shall have sufficient water stability and freezing stability. China has a vast territory, a large latitude span, rainy in the south and severe cold in the north. After repeated action of water and ice melting for a long time, the strength of pavement base will decrease and cracks will increase. Therefore, it is required that the pavement base must have sufficient water stability and freezing stability.

2. 1.3 The base under the rigid pavement should also have good drainage and sufficient erosion resistance. The phenomenon of "pumping mud" produced by rigid pavement base is often the main reason for the damage of rigid pavement. Therefore, in order to prevent the phenomenon of "pumping mud", the base under rigid pavement is required to have good drainage and certain anti-scouring ability.

2. 1.4 the pavement base should have enough smoothness, because the smoothness of the base not only directly affects the smoothness of the surface layer, but also affects the uniformity of the thickness of the surface layer, and the unevenness of the surface layer will directly affect the service life of the surface layer.

2. 1.5 the pavement base should be well combined with the base, because only in this way can the pavement structure-the surface layer and the base-become a whole and be in a completely continuous state of interfacial stress under wheel load, thus reducing the tensile stress and strain at the bottom of the asphalt base or semi-rigid base, and also reducing the internal stress and strain of the asphalt surface layer caused by temperature gradient, thus preventing the occurrence of asphalt pavement diseases.

2.2 Supervision points for preparation before construction

2.2. 1 Before construction, the supervision engineer shall examine and approve the construction technical scheme and the test scheme of the test section submitted by the contractor.

2.2.2 Before construction, the supervision engineer shall examine and approve the test of the contractor's raw materials. In the construction preparation stage, the supervision engineer shall require the contractor to take representative samples from the selected material yard, and make a complete analysis of soil particle analysis, plastic limit, liquid limit, plastic index, heavy compaction, stone screening, aggregate crushing value, calcium and magnesium content of lime, fineness and loss on ignition of fly ash and cement products (especially the final setting time of cement).

2.2.3 Examination and approval of mixture composition design. Before starting construction, the supervision engineer shall require the contractor to design the mixture composition of approved raw materials, determine the construction mixture ratio that meets the strength requirements, and report it to the supervision engineer for approval.

2.2.4 Review the configuration and quality of main mechanical equipment. Before construction, the supervision engineer shall require the contractor to use mixing equipment (factory mixing and road mixing), transportation equipment, paving equipment, leveling equipment, sprinkler equipment and various tonnage according to the variety, quantity and operation conditions of compaction equipment at different stages, and report to the supervision engineer for review.

2.2.5 The supervision engineer shall review the construction progress plan submitted by the contractor.

2.2.6 The supervision engineer shall review the contractor's construction lofting data, and check and verify the preparation of the lower bearing layer.

2.3 Key points of quality supervision in construction stage

2.3. 1 Quality supervision of cement stabilized soil base in construction stage

The cement stabilized soil mentioned here refers to cement stabilized macadam. The advantages of cement stabilized macadam base are good mechanical properties, good water stability, good frost resistance and high early strength, but it is easy to produce cracks. The content of cement is generally 4% ~ 8%, and the initial setting time of cement used is not less than 3 hours and 6 hours. The key to the construction control of cement stabilized macadam base is the tight flow operation, especially to shorten the engineering quantity from mixing to rolling as much as possible.

The construction of cement stabilized macadam base is mainly concentrated plant mixing method.

2.3.3. 1 The work flow of construction quality supervision of cement stabilized macadam base by factory mixing method is as follows:

Lower bearing layer preparation, construction setting-out, factory-mixed aggregate and mixture transportation and paving, shaping, rolling, joint and corner treatment and maintenance.

2.3. 1.2 Key points of quality supervision:

A preparation of the construction site supervision engineer should first check and accept its lower bearing layer. Its surface should be smooth and solid, without loose materials, weak points and lime-soil peeling phenomenon, and its elevation, width, transverse slope, flatness and compactness should meet the design or specification requirements.

B. The preparation and mixing supervision engineer of the mixture shall, on the premise of controlling the specifications (especially the maximum particle size) and quality of the mixture itself (the cement of the mixture can't be quick-hardening cement, early-strength cement or damp deteriorated cement), focus on supervising the correctness of the mixture composition and the uniformity of mixing, and control the water content slightly higher than the optimal water content.

C. Transportation and paving of the mixture should be delivered to the site as soon as possible. When necessary (high temperature and sandstorm), transport vehicles should be covered to prevent excessive water loss in the mixture. The mixture delivered to the site shall be paved with paver (or grader) in time. When paving the mixture, continuous operation should be carried out, and special personnel should be assigned to remove the segregation phenomenon of aggregates and fine aggregates. Cylindrical specimens of φ 10 cm× 15 or φ 15 cm× 15 shall be made on site and saturated for 7 days.

D the mixture shall not be shaped and stabilized. After paving the mixture, the supervision engineer shall immediately ask the contractor to shape and stabilize the mixture, and keep the specified slope and road arch during the shaping and stabilization, and pay attention to the smoothness and smoothness of the joints.

E. The supervision engineer of mixture compaction shall require the contractor to use a three-wheel roller, a heavy-duty tire roller or a vibratory roller of 12t or more to roll the mixture within the full width of the subgrade within the final setting time of cement determined by the test, and achieve the required degree of compaction. Compaction must be completed within the final setting time at the latest. During the rolling process, the surface of cement stabilized macadam should always be kept wet, and there should be no "spring", looseness, peeling and other phenomena. Rolling must be completed.

F the curing period of cement stabilized macadam base should not be less than 7d. When curing, it should be covered with impervious film or wet grass curtain, or sprayed with sprinkler frequently. In short, its surface should always be moist during the curing process. Traffic should be closed during the maintenance period, and when it is impossible to close, the speed limit can also be imposed on heavy vehicles and ordinary vehicles. At the end of the curing period, the prime asphalt shall be removed immediately.

2.3.2 Quality supervision of lime-fly ash stabilized soil base in construction stage

Lime-fly ash stabilized macadam soil refers to macadam stabilized with lime and fly ash, that is, lime-fly ash stabilized macadam. Lime-fly ash stabilized macadam has good mechanical properties, good plate property, water stability and certain frost resistance (its frost resistance is much higher than that of lime). It is also suitable for the base and subbase of various pavements, but not for the base and subbase of high-grade asphalt pavements. The ratio of lime to fly ash is generally 1: 2 ~ 1: 4, and the ratio of fly ash to aggregate is generally 15: 85 ~ 20: 80. In the composition of mixture, 1% ~ 2% cement should be added. The construction method is centralized plant mixing method.

2.3.3 Quality Supervision of Lime Stabilized Soil Base in Construction Stage

Lime stabilized soil base has good strength and water stability, but it is easy to produce cracks. Suitable for subbase, in frozen areas and areas with high groundwater level, waterproof and antifreeze layers should be laid under them. When the plasticity index of soil is 10 ~ 15 or more to 17, it is suitable for lime stabilization. The content of lime is generally 8% ~ 17.

In the construction of lime stabilized soil base, there are not only centralized factory mixing method for cement stabilized soil base construction, but also road mixing method and manual mixing method which can only be used for small-scale road projects below the second grade.

No matter which method is adopted, the following problems should be paid attention to in the construction process:

Lime soil should be constructed in late spring and summer. The lowest temperature during the construction period should be above 5℃, and it should be completed one month to one month before the first heavy freezing and thawing (-3℃ ~ 5℃). The stable soil layer should be cured by temperature and hot climate for more than half a month.

B in rainy areas, construction of lime-soil structure layer in rainy season should be avoided. If construction is carried out in rainy season, measures should be taken to prevent fine aggregate and lime from getting wet.

C quicklime should be fully digested for 7 ~ 10d before use, and the digested lime should be kept at a certain temperature, but it should not be too wet and caked.

D the digested lime should pass through a sieve with the aperture of 15mm and be used as much as possible.

E. The curing of lime stabilized soil should generally not be less than 7d. When curing, try to keep a certain humidity, not too wet or dry and wet. When curing, the method of wetting low cohesive soil is recommended.

2.3.3. 1 road mix construction quality supervision

Construction process flow

Preparation of bearing layer, construction setting-out, transportation of paving soil, leveling and compaction, transportation of lime, lime sprinkling, dry mixing, wet mixing with water, shaping, rolling, joint and corner treatment and maintenance.

B. Key points of quality supervision

In addition to the same parts as the centralized plant mixing method, the construction quality supervision of road mixing method should also pay full attention to "lime cow" and lime paving:

According to the composition design of the mixture, the "grey cow" was made. First, calculate the lime consumption per unit area. On the flat and compacted soil, several areas with the same width are divided along the road direction. In the divided area, the gray cattle with trapezoidal cross section are made regularly along the road direction, and the cross-sectional area of the gray cattle and the cross-sectional area of this layer of soil meet the requirements of mixture composition design. When making "Grey Bull"

B paving lime "grey cow" lime is generally paved by manual shovel. It is required to spread evenly and evenly.

C dry mixing wet mixing supervision engineer should control the mixing humidity in the process of dry mixing after spreading lime, strictly leave a layer of "plain soil" interlayer on the mixing layer, and also prevent too deep damage to the surface of the lower bearing layer. After dry mixing, the color of the mixture should be uniform, and there should be no lime concentration or no lime. If this problem exists, the dry mixing frequency should be increased. After dry mixing, if the water content of the mixture is insufficient, the nozzle type should be used.

D. Compacted lime-stabilized soil layer shall be compacted with a roller of 12T or more. After the mixture is mixed, it should be compacted within 3 ~ 4d.

E, the construction supervision of lime stabilized soil layer should control scraping instead of repairing, and strictly implement thin-layer repair.

The manual mixing method is adopted for the construction along the highway in 2.3.3.2, and the main points of supervision should be paid attention to:

A In the aspect of batching, the soil materials that need to be stabilized should be transported to the road according to the pre-calculated quantity per unit area of the mixture (or converted into volume), piled up into a continuous "earth cow", and then the slaked lime should be transported to the road according to the pre-calculated quantity per unit area (or converted into volume) and written on the "earth cow".

B In the aspect of mixing, the soil of "Tu Niu" is mixed with lime and passed through a sieve with the aperture of 15mm, and the remaining clods are crushed and sieved. After sieving, add a proper amount of water and stir evenly. After stirring, the materials will be stacked for one day.

C, according to the thickness of Matsuura, evenly pile the mixture after stirring and drilling.

For lime stabilized soil, no matter what construction method is adopted, if it is layered construction, a layer of lime stabilized soil can be paved immediately after the next layer of lime stabilized soil is rolled, and there is no need to set a special curing period for the next layer of lime stabilized soil.

3 quality supervision of asphalt concrete pavement

3. 1 asphalt concrete pavement quality requirements?

3. 1. 1 Asphalt pavement shall have sufficient pavement resistance. Pavement resistance, that is, pavement bearing capacity, is mainly used to balance pavement damage caused by excessive stress in pavement structure layer under repeated vehicle loads.

3. 1.2 Asphalt pavement should have good fatigue resistance. During the design service life, asphalt pavement should be able to bear a large number of repeated driving loads without premature damage. The main factors affecting the fatigue life of asphalt pavement are: compactness of asphalt mixture, asphalt content, aggregate characteristics (mineral aggregate gradation, mineral aggregate surface texture and shape), temperature and loading speed of fatigue test.

3. 1.3 Asphalt pavement should have good high temperature stability. The high temperature stability of asphalt pavement refers to the ability of asphalt mixture to resist repeated compression deformation and lateral flow of vehicles. Firstly, it depends on the mutual extrusion of mineral aggregate skeleton, especially coarse aggregate, and the gradation of aggregate; Secondly, the nature and dosage of asphalt mixture also play a restraining role in preventing the shear deformation of asphalt mixture.

3. 1.4 Asphalt mixture should have good low-temperature crack resistance. The low-temperature crack resistance of asphalt mixture mainly depends on the low-temperature tensile deformation performance of asphalt binder; Secondly, it is also related to the temperature shrinkage coefficient and tensile strength of asphalt mixture.

3. 1.5 Asphalt pavement should have good anti-skid performance. There are three factors affecting the anti-skid performance of asphalt pavement: microstructure, macro-structure and anti-skid pollution.

3.2 Supervision Points of Asphalt Pavement Construction Preparation

3.2. 1 The supervision engineer should first review the contractor's asphalt pavement construction organization design, and if it does not meet the requirements, it should be rewritten.

3.2.2 Review of raw materials. In the preparation stage of asphalt pavement construction, the supervision engineer first requires the contractor to test the physical properties and grades of raw materials (such as asphalt and various specifications of mineral aggregate) and report them to the supervision engineer for review and confirmation.

3.2.3 Examination and approval of mixture ratio. The supervision engineer shall require the contractor to carry out the mixture ratio test on the raw materials approved by the supervision engineer, and report the test results to the supervision engineer for approval.

3.2.4 Inspection of test equipment, mixing equipment and construction machinery and equipment in the mixing station. The supervision engineer shall require the contractor to set up a laboratory equipped with sufficient test equipment and qualified test personnel at the mixing station, check and debug the fully functional mixing equipment and the equipment, quantity and operation quality of various asphalt pavement construction machinery and equipment used in this project, and report to the supervision engineer.

3.2.5 Inspection and acceptance of construction materials and lower bearing layer. Before asphalt pavement construction, the supervision engineer shall examine and approve the contractor's construction materials preparation and self-inspection report of the underlying layer, including the following contents:

A the elevation, width, road arch, transverse slope and road centerline of the lower bearing layer must meet the design requirements;

B the surface of the lower bearing layer shall be smooth, clean, dry and solid, free from loose stones, dust and impurities, and free from pollution;

C. When the lower bearing layer is the base, the surface shall be sprayed with prime asphalt; When the lower bearing layer is the bottom of subbase and the bottom layer is paved for a long time, viscous asphalt should be sprayed.

3.2.6 Paving test section. The supervision engineer shall require the contractor to pave the test section with appropriate length 100 ~ 200m before the formal large-scale construction, and supervise the whole construction process of the test section, and finally examine and approve the test summary reported by the contractor.

3.3 Key points of asphalt pavement construction supervision

Asphalt concrete pavement structure has the advantages of high strength, good integrity and strong comprehensive resistance to natural factors. Suitable for all kinds of road surfaces. The minimum ambient temperature for asphalt pavement construction shall be no less than 10℃ for expressway and first-class highway, and no less than 5℃ for other grade highways.

3.3. 1 Main construction process

Cleaning and trimming the lower bearing layer-construction lofting-spraying prime asphalt as the lower bearing layer-mixing the asphalt mixture-transporting the asphalt mixture to the site-paving the asphalt mixture with a paver-rolling by a roller (initial pressure, second pressure and final pressure)-forming-sampling and testing.

3.3.2 The main points of construction supervision are as follows

3.3.2. 1 Mixing of asphalt mixture Under the condition of making good preparations before construction, the supervision engineer should pay attention to:

A. The quality supervision engineer of asphalt mixture mixing should strictly control the accurate calculation of various aggregates, mineral powder and asphalt according to the grading requirements of asphalt mixture.

B the mixing time of asphalt mixture should be 30 ~ 50s. The mixing temperature of asphalt mixture (asphalt heating temperature, mineral aggregate heating temperature and asphalt mixture outlet temperature) should meet the requirements listed in the table.

C. After mixing, the asphalt mixture must be uniform, and the coarse and fine materials must not be grayed, segregated and caked.

Transportation of asphalt mixture in 3.3.2.2 The mixed asphalt mixture shall be transported to the site in time by a dump truck with large tonnage metal floor, clean carriage and covered equipment. It should be covered, insulated, rain-proof and pollution-proof during transportation. If the hot mix asphalt mixture cannot be transported in time, it should be stored in the finished product storage bin, but the storage time should not exceed 72h.

3.3.2.3 asphalt mixture paving supervision engineer should strictly control the construction temperature of the mixture within the scope specified in the specification. Because of the different thickness of aggregate, the loose paving coefficient is about 1. 15 ~ 1.35. The paving speed of asphalt mixture should be determined according to the mixing capacity, paving thickness, width and the length of continuous paving, which should generally be controlled at 2 ~ 6m/min and should be carried out slowly.

3.3.2.4 asphalt mixture compaction and molding supervision engineer shall require the contractor to carry out joint compaction immediately after paving the mixture according to reasonable compaction technology. When pressing, the side should be first and then the middle, and turning, turning around and braking are not allowed on the freshly paved mixture. The supervision engineer shall check the temperature during rolling at any time. Strictly control the compaction quality of compaction machinery and asphalt mixture in different compaction stages. Supervision engineer should pay special attention to the construction quality of corners and joints. There should be a vertical plane at the joint, and the old facade should be painted with oil. During the traffic opening hours, the surface temperature of the mixture should be lower than 50℃ according to the regulations.

3.3.2.5 sampling test supervision engineer samples 1 ~ 2 times a day after each mixer is mixed, and conducts Marshall test, extraction test and screening test on the extracted asphalt mixture. Check whether the stability, flow value, density, porosity, asphalt content and mineral aggregate gradation meet the requirements of Marshall Test Technical Standard for Hot Mix Asphalt. The supervision engineer shall also carry out Marshall test, asphalt-aggregate ratio test and screening test for the mixture paved on site, and drill holes to sample the compacted asphalt concrete pavement to determine its thickness or measure its compactness with a nuclear densimeter.

Thermometer for construction of hot mix asphalt mixture

Asphalt varieties petroleum asphalt coal asphalt

The bidding number of Li Qing is ah-50ah-110ah-130a-200t-18t-15.

-70 AH- 100 AH- 140T-9-6

-90 AH 180 -7

-60

Heating temperature150 ~170140 ~160130 ~100 ~13080 ~120.

Concentrated ore

Temperature gap mixer is higher than asphalt heating temperature 10 ~ 20 (filler is not heated) and higher than asphalt heating temperature 15 (filler is not heated).

The continuous mixer is 5 ~ 10 higher than the asphalt heating temperature (filler heating) and 8% higher than the asphalt heating temperature (filler heating).

Factory temperature of mixture140 ~165125 ~120 ~15090 ~12080 ~10.

The temperature of the mixture decreased ≯ 10 during storage.

Transportation to site temperature ≮ 120 ~ 150 ≮ 90

arrange

Normal construction temperature ≮110 ~130 ≯165 ≮ 80 ≯120.

≮120 ~140 ≯175 ≮100 ≯140

submerge

Normal temperature construction110 ~140 ≮11080 ~165438 ≯ 75

Low temperature construction120 ~150 ≮1090 ~120 ≮ 85

submerge

(of a period) ending.

Steel roller temperature ≮70 ≮50

Tire roller 80 60

Vibratory roller ≮65 ≮50

After the road surface is cooled to the open circuit temperature (surface temperature ≮50)

Note: 1. Asphalt temperature is related to asphalt variety label. Thicker asphalt is used near the upper limit and thinner asphalt is used near the lower limit.

2. This form is not applicable to the construction of modified asphalt mixture;

Compaction quality control table

Inspection items of compaction times of compaction speed (km) during compaction.

Initial pressure 6-8t double-wheel steel roller

3- 10t vibratory roller (closed vibration) 1.5 ~ 2.02 road arch

flatness

2.5 ~ 3.5 of 8- 12 three-wheel steel wheel after recompression.

4.5 ~ 5.5 4 ~ 6 meet the requirements.

compact

There are no wheel tracks on the surface

12- 15 tire roller

20-25 tire roller