Method for evaluating hot-mix asphalt mixture, construction compaction and ease of application and use thereof

Abstract

This invention provides a method for evaluating the workability and compaction properties of hot-mix asphalt mixtures, and its application. The hot-mix asphalt mixture comprises asphalt, aggregates, mineral powder, and fibers. The passing percentages (%) of each sieve size (mm) in its gradation composition for 16, 13.2, 9.5, 4.75, 2.36, 1.18, 0.6, 0.3, 0.15, and 0.075 are respectively 100%, 95%–100%, 62.5%–75%, 27%–34%, 19.5%–26%, 16%–19%, 14%–16%, 13%–15%, 10%–13%, and 8%–12%. The fiber content of the hot-mix asphalt mixture is 0.3%–0.4%, and the asphalt-aggregate ratio is 6.0%–6.4%. The hot-mix asphalt mixture prepared by this invention has excellent workability and compaction properties. When applied to airport pavement repair, it can efficiently and effectively complete airport pavement repair work in environments with short nighttime airport hours and rapid temperature drops, with excellent results and is worthy of promotion.

Description

Technical Field

[0001] This invention belongs to the field of asphalt mixture technology, specifically relating to a hot-mix asphalt mixture, a method for evaluating the workability of construction compaction, and its application. Background Technology

[0002] Hot-mix asphalt mixture is a commonly used road material. Due to its excellent strength, durability, and low noise and dust during the production process, it is often used for pavement maintenance and repair. When the road surface is damaged or worn, hot-mix asphalt mixture can be used for repair or repaving in a timely manner.

[0003] However, in asphalt pavement repair projects, problems often arise such as poor adhesion of repair materials and poor compaction quality, affecting the repair effect. This is especially true for airport asphalt pavement repair, since most airport pavement repair work is carried out at night without interrupting flight operations. The hot-mix asphalt mixture used for airport pavement repair cools down relatively quickly, and the mixing and application of the hot-mix asphalt mixture must be completed in a very short time. Otherwise, the asphalt will re-solidify under the temperature drop, affecting the subsequent repair effect. In addition, the interval between flights at airports at night is only 4 to 5 hours, and the limited construction time, coupled with the simple and rapid construction, also reduces the compaction density of the pavement, further affecting the repair effect.

[0004] However, among commonly used technologies, there has been no targeted technical development for airport asphalt pavement repair projects that are short in duration and have rapid temperature drops, nor has there been targeted research on the repair materials used in such projects.

[0005] Therefore, it is necessary to propose an evaluation method for the workability of hot-mix asphalt mixtures and their application to address or at least mitigate the aforementioned defects. Summary of the Invention

[0006] To address the technical problem that commonly used technologies can only handle low-level purification requirements, this invention provides a hot-mix asphalt mixture. The hot-mix asphalt mixture comprises asphalt, aggregates, mineral powder, and fibers. The aggregate gradation includes: 100% pass rate through a 16mm sieve, 95%–100% through a 13.2mm sieve, 62.5%–75% through a 9.5mm sieve, 27%–34% through a 4.75mm sieve, 19.5%–22.5% through a 2.36mm sieve, 16%–19% through a 1.18mm sieve, 14%–16% through a 0.6mm sieve, 13%–15% through a 0.3mm sieve, 10%–13% through a 0.15mm sieve, and 8%–12% through a 0.075mm sieve.

[0007] The fiber content of the hot-mix asphalt mixture is 0.3% to 0.4%, and the asphalt-aggregate ratio of the hot-mix asphalt mixture is 6.0% to 6.4%.

[0008] Furthermore, the gradation comprises: a 100% pass rate for the 16mm sieve aperture, a 95%–98% pass rate for the 13.2mm sieve aperture, a 62.5%–69.5% pass rate for the 9.5mm sieve aperture, a 27%–30.5% pass rate for the 4.75mm sieve aperture, and a 10%–12% pass rate for the 0.075mm sieve aperture.

[0009] Furthermore, the aggregate with a particle size of 10-15 mm and the aggregate with a particle size of 5-10 mm include diabase crushed stone, the aggregate with a particle size of 3-5 mm includes limestone crushed stone, and the aggregate with a particle size of 0-3 mm includes limestone chips.

[0010] The mineral powder includes limestone mineral powder, the asphalt includes modified asphalt, and the fiber includes acrylic fiber.

[0011] This invention provides a method for evaluating the workability of hot-mix asphalt mixtures during construction compaction, comprising the following steps:

[0012] S1, test the porosity of Marshall specimens under different compaction conditions, and determine the relationship curve a between the number of compaction and porosity of the specimen based on the number of compaction and the corresponding porosity; the Marshall specimens are prepared by the specimens using the Marshall compaction test, and the specimens include the above-mentioned hot-mix asphalt mixture.

[0013] S2, obtain the target porosity range of the sample, and determine the upper limit curve b and the median curve c of the target porosity based on the target porosity range;

[0014] S3, determine whether the relationship curve a and the target porosity upper limit curve b have a first intersection point, and determine whether the relationship curve a and the target porosity median curve c have a second intersection point;

[0015] S41, when there is a first intersection between the relationship curve a and the target porosity upper limit curve b, and a second intersection between the compaction number and porosity relationship curve a and the target porosity median curve c, obtain the first compaction number corresponding to the first intersection and obtain the second compaction number corresponding to the second intersection, and proceed to S5;

[0016] S42, when there is a first intersection between the relationship curve a and the target porosity upper limit curve b, and there is no second intersection between the compaction number and porosity relationship curve a and the target porosity median curve c, obtain the first compaction number corresponding to the first intersection, and take the standard compaction number of the Marshall specimen as the second compaction number, and proceed to step S5;

[0017] S5, determine the average number of compaction times W based on the first number of compaction times and the second number of compaction times. ct Among them, W ct The smaller the value, the better the workability of construction compaction; and the better the nodal porosity W corresponding to the target number of compaction passes. vv Among them, W VV The smaller the value, the better the workability of construction compaction; the target number of times is the standard number of compaction times for Marshall specimens of highway asphalt mixtures.

[0018] S6, based on the average number of compaction times W ct Determine the first construction compaction and workability grade of the specimen, and based on the nodal porosity W. vv Determine the second construction compaction and workability grade of the specimen;

[0019] S7, determine whether the first construction compaction workability grade and the second construction compaction workability grade are consistent. If the first construction compaction workability grade and the second construction compaction workability grade are consistent, take the first construction compaction workability grade or the second construction compaction workability grade as the construction compaction workability grade of the sample; wherein, the construction compaction workability grade includes any one of excellent, good, medium and poor.

[0020] Furthermore, step S1, which involves determining the relationship curve a between the number of compactions and the corresponding porosity of the sample, specifically includes the following steps:

[0021] A two-dimensional rectangular coordinate system is established with the number of compactions as the x-axis and the void ratio corresponding to the number of compactions as the y-axis. The x-value of each number of compactions and the y-value of the corresponding void ratio are fitted sequentially to obtain the curve a of the relationship between the number of compactions and the void ratio.

[0022] Furthermore, the target porosity upper limit curve b is obtained through the following steps:

[0023] Based on the target porosity range, obtain the upper limit value of the porosity within the target porosity range;

[0024] Based on the upper limit value of the porosity, a horizontal straight line parallel to the x-axis is drawn to obtain the target porosity upper limit curve b;

[0025] The target porosity median curve c is obtained through the following steps:

[0026] Based on the target porosity range, obtain the upper limit and lower limit of the porosity within the target porosity range;

[0027] Determine the average porosity between the upper limit of porosity and the lower limit of porosity;

[0028] The target porosity median curve c is obtained by drawing a horizontal straight line parallel to the x-axis based on the average porosity.

[0029] Furthermore, step S3 is followed by the following step:

[0030] S31, when there is no first intersection between the curve a of the relationship between the number of compactions and the void ratio and the curve b of the upper limit of the target void ratio, and there is no second intersection between the curve a of the relationship between the number of compactions and the void ratio and the curve c of the median value of the target void ratio, the construction compaction workability grade of the sample is determined to be poor.

[0031] Furthermore, in step S6, based on the average number of compaction times W... ct Determining the first construction compaction and workability grade of the specimen specifically includes the following steps:

[0032] In W ct When the temperature is ≤40, the workability grade of the sample is determined to be excellent.

[0033] In 40 < W ct When the value is ≤55, the workability grade of the sample is determined to be good.

[0034] In 55 < W ct When the value is ≤70, the workability grade of the sample is determined to be medium.

[0035] In W ct When the value is greater than 70, the workability grade of the sample is determined to be poor.

[0036] Furthermore, in step S6, based on the node porosity W... vv Determining the second construction compaction and workability grade of the specimen specifically includes the following steps:

[0037] The upper limit value H of the target porosity of the sample is obtained according to the target porosity range. vv and the target porosity lower limit L vv ;

[0038] exist In the case of this, the workability grade of the sample is determined to be excellent.

[0039] exist In this case, the workability grade of the sample is determined to be good.

[0040] exist In this case, the workability grade of the sample is determined to be medium.

[0041] In W vv >H vv In the case of [condition], the workability grade of the sample is determined to be poor.

[0042] The present invention also provides an application of the evaluation method for the construction compaction and workability of hot-mix asphalt mixture as described in any of the above claims in airport pavement repair.

[0043] Compared with the prior art, the present invention has at least the following advantages:

[0044] This invention provides a hot-mix asphalt mixture and designs the mass ratio of mineral powder and various aggregates in the hot-mix asphalt mixture, the asphalt-aggregate ratio, and the fiber incorporation. The hot-mix asphalt mixture of this formula has excellent workability and compaction properties. When applied to airport pavement repair, it can quickly complete the mixing, paving, and compaction work in the environment of short nighttime airport hours and rapid temperature drop, and compact it to the specified density in a short time. It can complete the airport pavement repair work with both efficiency and quality, and ensure the subsequent operation of the airport pavement. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the relationship between the number of compaction passes and the porosity in one embodiment of the present invention.

[0047] Figure 2 This is a schematic diagram showing the relationship between the number of blows and the gap ratio of the ore in Embodiment 4 of the present invention.

[0048] Figure 3 This is a schematic diagram of the relationship between the number of blows and porosity in Embodiment 4 of the present invention.

[0049] Figure 4 This is a schematic diagram of the relationship between the number of blows and the asphalt saturation in Embodiment 4 of the present invention. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0052] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0053] Airport pavement repair is characterized by short duration, rapid temperature drop, and the stringent fatigue resistance requirements of airport pavements. This necessitates that repair materials possess excellent workability and compaction properties. In other words, during mixing, paving, and compaction, aggregate particles must quickly reach a uniform distribution, be completely covered by an asphalt film, and be compacted to the specified density to achieve a tight bond with the old pavement material.

[0054] Workability, in particular, is essentially the flow characteristic of a material, and is related to factors such as temperature, viscosity, and aggregate uniformity. Asphalt mixtures with good workability are easier to handle and control during construction, thereby improving construction quality and efficiency to meet the requirements of airport repair for both efficiency and quality.

[0055] This invention provides a hot-mix asphalt mixture, comprising asphalt, aggregates, mineral powder, and fibers. The aggregate gradation composition includes: 100% passing through a 16mm sieve, 95%–100% passing through a 13.2mm sieve, 62.5%–75% passing through a 9.5mm sieve, 27%–34% passing through a 4.75mm sieve, 19.5%–22.5% passing through a 2.36mm sieve, 16%–19% passing through a 1.18mm sieve, 14%–16% passing through a 0.6mm sieve, 13%–15% passing through a 0.3mm sieve, 10%–13% passing through a 0.15mm sieve, and 8%–12% passing through a 0.075mm sieve.

[0056] The fiber content of the hot-mix asphalt mixture can be 0.3% to 0.4%, and the asphalt-aggregate ratio of the hot-mix asphalt mixture can be 6.0% to 6.4%.

[0057] In some embodiments, in the gradation composition of the hot-mix asphalt mixture, the sieve passing rate of coarse aggregate (particle size greater than 4.75 mm, the same below) can all be above the median value of the SMA-13 ​​asphalt mixture gradation, that is, the passing rate of the 16 mm sieve is 100%, the passing rate of the 13.2 mm sieve is 95% to 98%, the passing rate of the 9.5 mm sieve is 62.5% to 69.5%, and the passing rate of the 4.75 mm sieve is 27% to 30.5%.

[0058] The gradation composition of the hot-mix asphalt mixture can have a 0.075mm sieve passing rate above the median value of the SMA-13 ​​asphalt mixture gradation, that is, the 0.075mm sieve passing rate (%) is 10% to 12%.

[0059] In other embodiments, the asphalt-aggregate ratio of the hot-mix asphalt mixture can be 6.0% to 6.2%.

[0060] It should be noted that the SMA-13 ​​gradation is used as the benchmark to adjust the passing rate of each sieve hole when designing the gradation because SMA contains more than 70% coarse aggregate. The coarse aggregates are in contact with each other and interlock with each other to form a strong "stone-stone contact" skeleton structure, which bears the main traffic load and greatly improves thermal stability. SMA is the first choice for all airport repair materials instead of AC.

[0061] Furthermore, due to repeated effects from airport loads and environmental factors, pavement structures will gradually deteriorate during use. This includes defects such as loosening, cracks, ruts, potholes, and subsidence. Some of these defects only affect the road's service performance, such as aggregate wear and bleeding, and are not very significant. Therefore, it is necessary to select SMA-13 ​​with a small particle size and sufficient strength.

[0062] For example, the aggregates with a particle size of 10-15 mm and the aggregates with a particle size of 5-10 mm include diabase crushed stone, the aggregates with a particle size of 3-5 mm include limestone crushed stone, and the aggregates with a particle size of 0-3 mm include limestone chips.

[0063] Among them, diabase is a basic shallow intrusive rock, whose main mineral components include pyroxene and basic plagioclase, as well as small amounts of olivine, biotite, quartz, apatite, magnetite and ilmenite.

[0064] In terms of surface characteristics, diabase ore is usually grayish-black and has a diabase structure, that is, the basic plagioclase is significantly more euhedral than pyroxene. Due to differences in mineral composition and formation environment, the surface characteristics of diabase ore also vary: some diabase ore has a smooth and delicate surface with obvious greasy luster; while others have a rough texture and feel.

[0065] Limestone, also known as limestone, is a carbonate rock primarily composed of calcite. Sometimes, limestone also contains dolomite, clay minerals, and detrital minerals. Limestone comes in a variety of colors, commonly including gray, grayish-white, grayish-black, yellow, light red, and brownish-red.

[0066] In some preferred embodiments, rough-surfaced diabase ore and limestone can be selected to increase the contact area between asphalt and aggregate, thereby improving adhesion. This adhesion is an important factor in ensuring the stability and durability of asphalt mixtures. When rough-surfaced aggregates are mixed with asphalt, they can better resist external forces and are less prone to peeling or separation. At the same time, rough-surfaced aggregates can provide better fatigue resistance and durability, thereby increasing the service life of asphalt pavements.

[0067] In some embodiments, the apparent density of diabase with a grain size of 5–10 mm can be 2.766 g·cm³. -3 The bulk density of the hair can be 2.703 g·cm³. -3 The water absorption rate can be 0.85%.

[0068] The apparent density of diabase with a grain size of 10–15 mm can be 2.769 g·cm³. -3 The bulk density of the hair can be 2.707 g·cm³. -3 The water absorption rate can be 0.84%.

[0069] The apparent density of limestone gravel with a particle size of 3–5 mm can be 2.744 g·cm³. -3 The bulk density of the hair can be 2.696 g·cm³. -3 The water absorption rate can be 0.91%.

[0070] The apparent density of limestone chips with a particle size of 0–3 mm can be 2.702 g·cm³. -3 .

[0071] In other embodiments, the mineral powder includes limestone mineral powder, which may have an apparent relative density of 2.782 g·cm³. -3 .

[0072] Modified asphalt includes ID SBS modified asphalt, whose Chinese name is "styrene-butadiene-styrene modified asphalt," and whose density is 1.03 g·cm³. -3 The penetration at 25℃ is 5.6 mm, the ductility at 5℃ is 26.3 cm, the softening point is 76.6℃, the kinematic viscosity at 135℃ is 1.9 Pa·s, the residual penetration ratio is 74.7%, and the residual ductility at 5℃ is 16.5 cm.

[0073] The fiber includes acrylic fiber with a specific gravity of 1.36 g·cm³. -3 .

[0074] The asphalt-aggregate ratio refers to the percentage of the mass ratio of asphalt to aggregate in asphalt concrete, and it is one of the indicators of asphalt content. In some embodiments, the asphalt-aggregate ratio can be the mass ratio of asphalt to aggregate and mineral powder in hot-mix asphalt mixtures, i.e., m(asphalt) / m(aggregate + mineral powder).

[0075] The aforementioned aggregate gradation ratio, mineral powder admixture design, and aggregate type selection enable the aggregate to quickly achieve uniform distribution, with its surface completely coated by an asphalt film, and to be compacted to the specified density, achieving a tight bond with the old pavement material. Simultaneously, the hot-mix asphalt mixture exhibits excellent fluidity, making it easier to operate and control during paving. In other words, the hot-mix asphalt mixture of this invention possesses good workability and compaction properties, performing well in the entire pavement repair process, from mixing and paving to rolling, thus meeting the construction requirements of hot-mix asphalt mixtures for airport pavement repairs characterized by short durations and rapid temperature drops.

[0076] Meanwhile, the hot-mix asphalt mixture with the above-mentioned proportions exhibits excellent fatigue resistance after being applied to pavement repair: During use, due to the repeated action of landing gear loads, the asphalt pavement is in a state of stress-strain superposition for a long time, which may lead to a gradual decrease in the pavement structural strength. When the load is repeated more than a certain number of times, the stress generated by the load on the pavement may exceed the structural resistance after the strength has decreased, leading to pavement cracking and fatigue fracture failure.

[0077] Based on the proportion settings of aggregates and mineral powder at each level and the adjustment of the asphalt-aggregate ratio in this invention, the mechanical properties and porosity of hot-mix asphalt mixtures are optimized after application, giving the material excellent fatigue resistance.

[0078] For example, the aggregate gradation composition includes: 100% pass rate through a 16mm sieve, 97.9% pass rate through a 13.2mm sieve, 69.2% pass rate through a 9.5mm sieve, 30.3% pass rate through a 4.75mm sieve, 22.3% pass rate through a 2.36mm sieve, 18.1% pass rate through a 1.18mm sieve, 16.0% pass rate through a 0.6mm sieve, 14.2% pass rate through a 0.3mm sieve, 10.7% pass rate through a 0.15mm sieve, and 10.6% pass rate through a 0.075mm sieve.

[0079] As another example, the fiber content of the hot-mix asphalt mixture is 0.3%, and the asphalt-aggregate ratio of the hot-mix asphalt mixture is 6.2%.

[0080] As a preferred embodiment, the composition of the hot-mix asphalt mixture is further adjusted to further optimize the workability, compaction, and fatigue resistance of the aforementioned hot-mix asphalt mixture, thereby achieving targeted application for airport pavement repair.

[0081] This invention provides a method for evaluating the workability of hot-mix asphalt mixtures during construction compaction, applicable to the evaluation of the workability of hot-mix asphalt mixtures as described in any of the above-mentioned methods, comprising the following steps:

[0082] S1, test the void ratio of the Marshall specimen under different compaction number conditions, and determine the relationship curve a between the number of compaction numbers and the void ratio of the specimen based on the number of compaction numbers and the corresponding void ratio; the Marshall specimen is prepared by the specimen using the Marshall compaction test, and the specimen includes any of the hot-mix asphalt mixtures described above.

[0083] Furthermore, step S1, determining the relationship curve a between the number of compactions and the corresponding void ratio, specifically includes the following steps: establishing a two-dimensional rectangular coordinate system with the number of compactions as the x-axis and the void ratio corresponding to the number of compactions as the y-axis; sequentially fitting the x-value of each compaction number with the corresponding y-value of the void ratio to obtain the relationship curve a between the number of compactions and the void ratio. For details, please refer to the appendix. Figure 1 As shown.

[0084] S2, obtain the target porosity range of the sample, and determine the upper limit curve b and the median curve c of the target porosity based on the target porosity range.

[0085] In some embodiments, the target porosity of the hot-mix asphalt mixture in this invention is 3% to 5%.

[0086] For airport repair scenarios, the common compaction and workability standards for hot-mix asphalt mixtures used in airports are shown in the table below:

[0087] Table 1 Standards for Compaction and Workability of Hot-Mix Asphalt Mixtures in Commonly Used Technologies

[0088]

[0089] As shown in the table above, H VV L is the upper limit of the target porosity. VV Since the target porosity is the lower limit, the target porosity range of the sample can be obtained by obtaining the mixture type of the sample, so as to determine the target porosity upper limit curve b and the target porosity median curve c according to the target porosity range.

[0090] Furthermore, the target porosity upper limit curve b is obtained through the following steps:

[0091] Based on the target porosity range, obtain the upper limit value of the porosity within the target porosity range;

[0092] Based on the upper limit value of the porosity, a horizontal straight line parallel to the x-axis is drawn to obtain the upper limit curve b of the target porosity.

[0093] Furthermore, the target porosity median curve c is obtained through the following steps:

[0094] Based on the target porosity range, obtain the upper limit and lower limit of the porosity within the target porosity range;

[0095] Determine the average porosity between the upper limit of porosity and the lower limit of porosity;

[0096] The target porosity median curve c is obtained by drawing a horizontal straight line parallel to the x-axis based on the average porosity.

[0097] The target porosity upper limit curve b and the target porosity median curve c mentioned above can both be found in the appendix. Figure 1 As shown.

[0098] S3, determine whether there is a first intersection between the curve a of the relationship between the number of compactions and the void ratio and the upper limit curve b of the target void ratio, and determine whether there is a second intersection between the curve a of the relationship between the number of compactions and the void ratio and the median curve c of the target void ratio.

[0099] It should be noted that, in order to quantify the workability of the test specimens during construction compaction, this application determines whether there is a first intersection between the curve a showing the relationship between the number of compactions and the porosity and the upper limit curve b showing the target porosity, and whether there is a second intersection between the curve a showing the relationship between the number of compactions and the porosity and the median curve c showing the target porosity. For details, please refer to the appendix. Figure 1 .

[0100] Specifically, in conjunction with the appendix Figure 1 It can be seen that, based on whether the porosity relationship curve a intersects with the target porosity upper limit curve b and the target porosity median curve c, there are three possible scenarios for the porosity relationship curve a. One is that the porosity relationship curve a intersects with the target porosity upper limit curve b and the target porosity median curve c simultaneously (i.e., it has the first intersection point and the second intersection point), such as... Figure 1 curve a in 1 One type is where the porosity relationship curve a intersects with the target porosity upper limit curve b, but does not intersect with the target porosity median curve c (i.e., it has a first intersection point but not a second intersection point), such as... Figure 1 curve a in 2 Another scenario is where the porosity relationship curve a does not intersect with either the target porosity upper limit curve b or the target porosity median curve c (in this case, there is neither a first intersection point nor a second intersection point), such as... Figure 1 curve a in 3 .

[0101] In some embodiments, step S3 is followed by the following step:

[0102] S31, when the curve a showing the relationship between the number of compactions and the porosity does not have a first intersection point with the upper limit curve b showing the target porosity, and when the curve a showing the relationship between the number of compactions and the porosity does not have a second intersection point with the median curve c showing the target porosity, the workability grade of the sample is determined to be poor. This situation corresponds to the attached... Figure 1 curve a in 3 In this situation, for example, when the number of compaction passes reaches 75, the corresponding void ratio is above the upper limit of the target void ratio. At this time, the void ratio of the asphalt mixture is still very high, which will seriously affect the bonding performance and compaction quality of the repair material. Therefore, it is judged as poor workability in construction compaction.

[0103] S41, when there is a first intersection between the relationship curve a and the target porosity upper limit curve b, and a second intersection between the compaction number and porosity relationship curve a and the target porosity median curve c, obtain the first compaction number corresponding to the first intersection and obtain the second compaction number corresponding to the second intersection, and proceed to S5;

[0104] S42, when there is a first intersection between the relationship curve a and the target void ratio upper limit curve b, and there is no second intersection between the compaction number and void ratio relationship curve a and the target void ratio median curve c, obtain the first compaction number corresponding to the first intersection, and take the standard compaction number of the airport asphalt mixture Marshall specimen as the second compaction number, and proceed to step S5.

[0105] S5, determine the average number of compaction times W based on the first number of compaction times and the second number of compaction times. ct And determine the node porosity W corresponding to the target number of compaction hits. vv .

[0106] It is worth noting that W CT (Workability Compacting Times) refers to the average number of compaction times corresponding to the first and second intersections, W. CT The smaller the value, the better the workability during construction compaction. This method can visually describe the relationship between the number of compaction passes and the void ratio of asphalt mixtures. From the relationship curve, the workability of different mixtures during construction compaction can be clearly compared, which can provide good guidance for the number of compaction passes in the process of airport asphalt pavement repair.

[0107] W VV Workability Void Volume (W) refers to the void ratio corresponding to the target number of compaction passes for a Marshall specimen (usually based on a standard of 50 passes for highway asphalt mixture Marshall specimens). VV The smaller the size, the better the compaction and workability during construction. This method is simple to operate and requires less work.

[0108] S6, based on the average number of compaction times W ct Determine the first construction compaction and workability grade of the specimen, and based on the nodal porosity W. vv Determine the second construction compaction and workability grade of the specimen.

[0109] As a preferred embodiment, a standardized workability grade for the construction compaction of the test specimens is established. This workability grade includes any one of excellent, good, medium, and poor. Those skilled in the art know that the standard compaction number for Marshall specimens of airport asphalt mixtures is 75 blows, and for highway asphalt mixtures it is 50 blows. Furthermore, laboratory tests have shown that when the number of compaction blows exceeds 55, the porosity of some asphalt mixtures tends to stabilize. In view of the above three points, the embodiments of this application adopt W... CT 40, 55, and 70 are used as the dividing points for the classification of construction compaction and workability grades.

[0110] Specifically, step S6, which determines the first construction compaction workability grade of the sample based on the average number of compaction times, Wct, includes the following steps:

[0111] When Wct≤40, the workability grade of the sample is determined to be excellent.

[0112] When 40 < Wct ≤ 55, the workability grade of the sample is determined to be good.

[0113] When 55 < Wct ≤ 70, the workability grade of the sample is determined to be medium.

[0114] When Wct > 70, the workability grade of the sample is determined to be poor.

[0115] As a preferred implementation method, in order to work with W CT The standard for construction compaction and workability is consistent with the proposed upper limit of target porosity (H). VV ) and target porosity lower limit (L VV The three equal division points of the above form serve as the dividing points for the classification of construction compaction and workability grades. The compaction and workability standards for hot-mix asphalt mixtures commonly used in airports can be obtained from the above form. For example, when the type of hot-mix asphalt mixture is SMA-13, the upper limit of the target void ratio H is... VV The target porosity lower limit L is 5%. VV It is 3%.

[0116] Specifically, step S6, determining the second construction compaction and workability grade of the sample based on the nodal porosity Wvv, includes the following steps:

[0117] The upper limit value Hvv and the lower limit value Lvv of the target porosity of the sample are obtained according to the target porosity range.

[0118] exist In the case of this, the workability grade of the sample is determined to be excellent.

[0119] exist In this case, the workability grade of the sample is determined to be good.

[0120] exist In this case, the workability grade of the sample is determined to be medium.

[0121] In W vv >H vv In the case of [condition], the workability grade of the sample is determined to be poor.

[0122] S7, determine whether the first construction compaction workability grade and the second construction compaction workability grade are consistent. If the first construction compaction workability grade and the second construction compaction workability grade are consistent, take the first construction compaction workability grade or the second construction compaction workability grade as the construction compaction workability grade of the sample; wherein, the construction compaction workability grade includes any one of excellent, good, medium and poor.

[0123] It is worth noting that this application obtains the corresponding first and second construction compaction workability grades through two methods. By comparing whether the first and second construction compaction workability grades are consistent, when they are consistent, either the first or second construction compaction workability grade is taken as the construction compaction workability grade of the sample. That is, when they are consistent, the two methods have good consistency, improving the accuracy of determining the construction compaction workability grade of the sample, i.e., W. CT The mutual verification process between the method and Wvv.

[0124] This invention also provides the application of the evaluation method for the workability of hot-mix asphalt mixtures as described in any of the above claims in airport pavement repair.

[0125] To facilitate a further understanding of the present invention by those skilled in the art, the following examples are provided:

[0126] Example 1

[0127] Three groups of samples were taken, and the compositional characteristics of the three groups of samples were as follows:

[0128] Sample 1: The coarse aggregate (particle size greater than 4.75mm) in the hot-mix asphalt mixture gradation composition all had a sieve passing rate above the median value of the SMA-13 ​​asphalt mixture gradation.

[0129] The passing rate of the 4.75mm sieve is close to the upper limit of 34% of the SMA-13 ​​gradation, which is 33.9; the passing rate of the 0.075mm sieve is above 10% of the median value of the SMA-13 ​​asphalt mixture gradation, which is 10.9.

[0130] Sample 2: The coarse aggregate (particle size greater than 4.75mm) in the hot-mix asphalt mixture gradation composition all had a sieve passing rate above the median value of the SMA-13 ​​asphalt mixture gradation.

[0131] The passing rate of the 4.75mm sieve is close to the average of 30.5% of the median value of SMA-13 ​​gradation (27%) and the upper limit value of SMA-13 ​​gradation (34%), which is 30.3%; the passing rate of the 0.075mm sieve is above 10% of the median value of SMA-13 ​​asphalt mixture gradation, which is 10.4%.

[0132] Sample 3: The coarse aggregate (particle size greater than 4.75mm) sieve passing rate of the hot-mix asphalt mixture was basically above the median value of the SMA-13 ​​asphalt mixture gradation.

[0133] The passing rate through a 4.75mm sieve is close to the median of 27% for SMA-13 ​​asphalt mixture gradation, at 26.9%, while the passing rate through a 0.075mm sieve is above 10% for SMA-13 ​​asphalt mixture gradation, at 10.4%.

[0134] The gradation composition of the three groups of samples is shown in Table 2.

[0135] Table 2. Gradation and Proportioning Composition

[0136]

[0137]

[0138] Three groups of Marshall specimens were selected for initial testing with an asphalt-aggregate ratio of 6.2%. Acrylic fiber content was 0.3% of the hot-mix asphalt mixture mass. The compaction temperature for the Marshall specimens was 175℃–180℃. Considering the heavy load characteristics of airports, the number of compaction passes per surface was set at 75. The porosity (VV) of the Marshall specimens, the aggregate void ratio (VMA), and the coarse aggregate void ratio (VCA) of the asphalt mixture specimens were tested. mix Coarse aggregate loose packing gap ratio (VCA) DRC The volumetric parameters, such as asphalt saturation (VFA), were analyzed, and the results are shown in Table 3.

[0139] Table 3 Marshall volume parameters for initial gradation

[0140]

[0141] As shown in Table 3, the Marshall volume parameters of hot-mix asphalt mixtures in Schemes 2 and 3 can meet the VCA (Variable Capacity Parameter) requirements. mix Less than VCA DRC In accordance with the requirement that VMA is greater than 16.5% and simultaneously meet the design requirements of void fraction volume parameters, and following the principle that "when more than one gradation meets the relevant requirements of VCA, the gradation with a pass rate of 4.75mm is used as the design gradation", and referring to similar engineering experience, the gradation of sample two is adopted as the target gradation.

[0142] Example 2

[0143] Based on the gradation of sample 2 in Example 1, five oil-aggregate ratios were selected at 0.2% intervals: 5.6%, 5.8%, 6.0%, 6.2%, and 6.4%, building upon the 6.2% oil-aggregate ratio in Example 1. Marshall specimens were molded under these five different oil-aggregate ratios, and the volumetric parameters and mechanical properties were tested. The test results are shown in Table 4.

[0144] Table 4. Marshall volumetric parameters and mechanical properties for different oilstone ratios.

[0145]

[0146]

[0147] According to the test results, the target gradation meets the relevant specifications for an asphalt-aggregate ratio of 6.0% to 6.4%. In the table above, VV is the void ratio, VMA is the aggregate void ratio, and VFA is the asphalt saturation. The same applies below.

[0148] Example 3

[0149] Marshall specimens with oil-stone ratios of 6.2% and 6.0% were selected from the range of oil-stone ratios that meet the relevant specifications, and their properties such as high-temperature stability, low-temperature crack resistance, water stability, and adhesion were tested. The test results are shown in Table 5.

[0150] Table 5 Summary of Technical Specifications for Hot-Mix Asphalt Repair Materials for Airport Pavements

[0151]

[0152] According to the test results in Table 5, when the asphalt-aggregate ratio is 6.2% and 6.0%, all performance indicators of the airport hot-mix asphalt repair material meet the specifications and technical requirements.

[0153] Example 4

[0154] The study investigated the construction compaction and workability of hot-mix asphalt mixtures for airport repair, in accordance with W... CT or W VV This method determines the workability grade of hot-mix asphalt mixtures for airport construction through compaction. Marshall specimens were prepared with asphalt-aggregate ratios of 6.0% and 6.2%. The number of compaction passes was varied from 75 to 35 at 10-fold intervals. Various volumetric parameters of the Marshall specimens under each compaction pass condition were tested, and the results are shown in the table below. Figures 2-4 .

[0155] Table 6 Relationship between compaction number and Marshall volume parameters

[0156]

[0157] From the above table and Figures 2-4It can be seen that with the increase of Marshall compaction times, the bulk density and asphalt saturation of hot-mix asphalt mixtures tend to increase, while the aggregate void ratio and porosity tend to decrease. However, when the asphalt-aggregate ratio is 6.0%, the increasing or decreasing trend continues; when the asphalt-aggregate ratio is 6.2% and the number of compaction times is less than 55, the increasing or decreasing trend also continues, and the rate of change is faster than when the asphalt-aggregate ratio is 6.0%; when the asphalt-aggregate ratio is 6.2% and the number of compaction times is greater than 55, the volumetric parameters tend to stabilize. Therefore, in the embodiments of this application, the hot-mix asphalt mixture for airport repair with an asphalt-aggregate ratio of 6.2% has relatively better workability for construction compaction.

[0158] The following quantitative analysis is conducted based on the proposed indicators and standards for construction compaction and workability.

[0159] ①With W CT The target void ratio requirement for hot-mix asphalt mixtures used for airport repairs is 3%–5%, therefore the median target void ratio is 4%. Figure 4 The relationship curve between the number of compaction passes and the void ratio VV shows that when the oil-aggregate ratio is 6.0%, there is a first intersection point and a second intersection point corresponding to curve d, with corresponding compaction passes of 51 and 75. Therefore, W CT =63. According to the above examples, the workability grade of construction compaction is medium; when the asphalt-aggregate ratio is 6.2%, there is a first intersection point and a second intersection point (corresponding to the median curve), with corresponding compaction times of 36 and 46 respectively. Therefore, W CT =41, the workability grade of construction compaction is good.

[0160] ②With W VV Let's look at: Target porosity upper limit H VV =5%, target porosity lower limit L VV =3%. By Figure 4 The relationship curve between the number of compaction cycles and the void ratio VV shows that when the asphalt-aggregate ratio is 6.0%, the void ratio W corresponding to 50 compaction cycles of the Marshall specimen is... VV =5.0%, according to the determination standard of SMA-13 ​​in the table above, the workability grade of construction compaction is medium; when the asphalt-aggregate ratio is 6.2%, the void ratio W corresponding to 50 compactions of the Marshall specimen is... VV =3.8%, W in conjunction with the above embodiments VV It can be determined that the workability grade of the construction compaction is good.

[0161] Quantitative analysis shows that the two methods and standards have good consistency. As a preferred example, considering the operability and convenience of determining the workability grade of construction compaction, it is recommended to use the porosity W corresponding to 50 compactions of a Marshall specimen. VVThis study aimed to determine the workability of hot-mix asphalt mixtures for airport repair. Furthermore, the asphalt content significantly affects the workability of hot-mix asphalt mixtures; a 6.2% asphalt-aggregate ratio resulted in better workability than a 6.0% asphalt-aggregate ratio, consistent with theoretical analysis.

[0162] Taking into account the high-temperature stability, water stability, low-temperature crack resistance, and workability of hot-mix asphalt repair materials for airports, the asphalt-aggregate ratio was determined to be 6.2%, and the raw material ratio was: 10-15mm particle size: 5-10mm particle size: 3-5mm particle size: 0-3mm particle size: mineral powder in a ratio of 36:40:0:12:12, with an acrylic fiber content of 0.3%. It was applied to Shanghai Hongqiao International Airport and the application effect was good.

[0163] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for evaluating the workability of hot-mix asphalt mixtures during construction compaction, characterized in that, This hot-mix asphalt mixture, used in airport pavement repair, comprises asphalt, aggregates, mineral powder, and fibers. The aggregates with a particle size of 10-15mm and 5-10mm include rough-surfaced diabase crushed stone, while the amount of 3-5mm aggregate is zero. The mass ratio of the 10-15mm, 5-10mm, 0-3mm aggregates, and mineral powder is 36:40:12:

12. The aggregate gradation includes: 100% passing through a 16mm sieve, and 13.2... The passing rates for sieves with apertures of 1 mm, 9.5 mm, 4.75 mm, 20.5%, 2.36 mm, 1.18 mm, 0.6 mm, 0.3 mm, 0.15 mm, and 0.075 mm are 95%–98%, 62.5%–69.5%, 27%–30.5%, 20.5%–22.5%, 16%–19%, 14%–16%, 13%–15%, 10%–13%, and 10%–12%, respectively. The fiber content of the hot-mix asphalt mixture is 0.3%~0.4%, and the asphalt-aggregate ratio of the hot-mix asphalt mixture is 6.2%. The evaluation method includes the following steps: S1, test the porosity of Marshall specimens under different compaction conditions, and determine the relationship curve a between the number of compaction and porosity of the specimen based on the number of compaction and the corresponding porosity; the Marshall specimens are prepared by the specimens using the Marshall compaction test, and the specimens include the above-mentioned hot-mix asphalt mixture. S2, obtain the target porosity range of the sample, and determine the upper limit curve b and the median curve c of the target porosity based on the target porosity range; S3, determine whether the relationship curve a and the target porosity upper limit curve b have a first intersection point, and determine whether the relationship curve a and the target porosity median curve c have a second intersection point; S41, when there is a first intersection between the relationship curve a and the target porosity upper limit curve b, and a second intersection between the compaction number and porosity relationship curve a and the target porosity median curve c, obtain the first compaction number corresponding to the first intersection and obtain the second compaction number corresponding to the second intersection, and proceed to S5; S42, when there is a first intersection between the relationship curve a and the target void ratio upper limit curve b, and there is no second intersection between the relationship curve a of the number of compactions and void ratio and the target void ratio median curve c, obtain the first number of compactions corresponding to the first intersection, and take the standard number of compactions of the highway asphalt mixture Marshall specimen as the second number of compactions, and proceed to step S5; S5, determining a compaction frequency average value W according to the first compaction frequency and the second compaction frequency CT wherein, W CT The smaller, the better construction compaction and workability; and determining the node void ratio W corresponding to the target number of compaction frequencies VV wherein, W VV The smaller, the better construction compaction and workability; the target number is the standard compaction frequency of the Marshall test piece of the highway asphalt mixture S6, based on the average number of compaction times W CT Determine the first construction compaction and workability grade of the specimen, and based on the nodal porosity W. VV Determine the second construction compaction and workability grade of the specimen; S7, determine whether the first construction compaction workability grade and the second construction compaction workability grade are consistent. If the first construction compaction workability grade and the second construction compaction workability grade are consistent, take the first construction compaction workability grade or the second construction compaction workability grade as the construction compaction workability grade of the sample; wherein, the construction compaction workability grade includes any one of excellent, good, medium and poor.

2. The method for evaluating the workability of hot-mix asphalt mixtures during construction according to claim 1, characterized in that, The aggregate with a particle size of 3-5 mm includes limestone crushed stone, and the aggregate with a particle size of 0-3 mm includes limestone rock chips; The mineral powder includes limestone mineral powder, the asphalt includes modified asphalt, and the fiber includes acrylic fiber.

3. The method for evaluating the workability of hot-mix asphalt mixtures during construction according to claim 1, characterized in that, The step S1, which involves determining the relationship curve a between the number of compactions and the corresponding porosity of the sample, specifically includes the following steps: A two-dimensional rectangular coordinate system is established with the number of compactions as the x-axis and the void ratio corresponding to the number of compactions as the y-axis. The x-value of each number of compactions and the y-value of the corresponding void ratio are fitted sequentially to obtain the curve a of the relationship between the number of compactions and the void ratio.

4. The method for evaluating the workability of hot-mix asphalt mixtures during construction according to claim 1, characterized in that, The target porosity upper limit curve b is obtained through the following steps: Based on the target porosity range, obtain the upper limit value of the porosity within the target porosity range; Based on the upper limit value of the porosity, a horizontal straight line parallel to the x-axis is drawn to obtain the target porosity upper limit curve b; The target porosity median curve c is obtained through the following steps: Based on the target porosity range, obtain the upper limit and lower limit of the porosity within the target porosity range; Determine the average porosity between the upper limit of porosity and the lower limit of porosity; The target porosity median curve c is obtained by drawing a horizontal straight line parallel to the x-axis based on the average porosity.

5. The method for evaluating the workability of hot-mix asphalt mixtures during construction compaction according to claim 1, characterized in that, The step S3 is followed by the following step: S31, when there is no first intersection between the curve a of the relationship between the number of compactions and the void ratio and the curve b of the upper limit of the target void ratio, and there is no second intersection between the curve a of the relationship between the number of compactions and the void ratio and the curve c of the median value of the target void ratio, the construction compaction workability grade of the sample is determined to be poor.

6. The method for evaluating the workability of hot-mix asphalt mixtures during construction according to claim 1, characterized in that, In step S6, the average number of compactions W is used as the basis. ct Determining the first construction compaction and workability grade of the specimen specifically includes the following steps: In W ct When the temperature is ≤40, the workability grade of the sample is determined to be excellent. In 40 < W ct When the value is ≤55, the workability grade of the sample is determined to be good. In 55 < W ct When the value is ≤70, the workability grade of the sample is determined to be medium. In W ct When the value is greater than 70, the workability grade of the sample is determined to be poor.

7. The method for evaluating the workability of hot-mix asphalt mixtures during construction according to claim 1, characterized in that, In step S6, the node porosity W is used as a reference. vv Determining the second construction compaction and workability grade of the specimen specifically includes the following steps: The upper limit value H of the target porosity of the sample is obtained according to the target porosity range. vv and the target porosity lower limit L vv ; In W vv ≤ In the case of this, the workability grade of the sample is determined to be excellent. exist <W vv ≤ In this case, the workability grade of the sample is determined to be good. exist <W vv ≤H vv In this case, the workability grade of the sample is determined to be medium. In W vv >H vv In the case of [condition], the workability grade of the sample is determined to be poor.

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