A pavement material

Abstract

The application provides a pavement material, which comprises aggregate, and the aggregate comprises at least nine gradations, and the at least nine gradations are in order from large to small according to the particle size of the aggregate, 13.2mm is 90%-100%, 9.5mm is 50%-75%, 4.75mm is 20%-34%, 2.36mm is 15%-26%, 1.18mm is 14%-24%, 0.6mm is 12%-20%, 0.3mm is 10%-16%, 0.15mm is 9%-15%, and 0.075mm is 8%-12%. By adjusting the proportion of each gradation of the aggregate, the AC material with the noise reduction performance not inferior to that of the conventional SMA material can be provided, and in the environment with large diurnal temperature difference, the noise reduction performance of the AC material does not fluctuate sharply with the temperature change and the excellent low-temperature tensile capacity is maintained, so that the pavement material can be widely applied to the little-rain and arid areas and is low in cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete materials, and particularly relates to a pavement material. BACKGROUND

[0002] Concrete material is an important raw material for road construction. Common concrete materials for pavement include AC material and SMA material. The components of SMA material use modified asphalt, so its noise reduction performance, aging resistance and durability, and crack resistance and tensile resistance are all superior to those of conventional AC material. Therefore, in areas with high requirements for road construction, SMA material is usually selected for construction.

[0003] However, SMA material also has many problems.

[0004] Firstly, SMA material must use modified asphalt, and the additive composition and addition amount of modified asphalt need to be determined according to its requirements and the balance of the performance of the composite material, that is, the performance of modified asphalt will be affected by the additives of different manufacturers and the actual pavement environment, which causes that SMA material using the same component ratio of modified asphalt of different manufacturers applied in the same pavement environment may achieve different performance effects, and the same component ratio of modified asphalt of the same manufacturer may not be suitable for different pavement environments in the same area.

[0005] Secondly, SMA material is discontinuous gradation, and the northwest plateau region has large temperature difference between morning, noon and evening, and belongs to a dry and rainy environment, which will cause the gap between different gradations of aggregates to change greatly. This change greatly affects the noise reduction effect of pavement material. In SMA material, noise reduction powder is usually added to modified asphalt or rubber modified asphalt is used to improve the noise reduction performance, which not only leads to complex pavement material preparation, but also has high cost. SUMMARY

[0006] Therefore, the present application provides a pavement material to solve the problems that SMA material uses modified asphalt, the performance of SMA material is easily affected by additives of different manufacturers and the actual pavement environment, and if it needs to be suitable for a dry and rainy environment with large temperature difference between day and night, noise reduction powder needs to be added or rubber modified asphalt needs to be used to improve the noise reduction performance, which leads to complex preparation and high cost.

[0007] The technical scheme of the present application is implemented as follows: the present application provides a pavement material, which comprises aggregate, and the aggregate comprises at least nine gradations, and the at least nine gradations are in order from large to small according to the particle size of the aggregate, and the particle size of the aggregate is 13.2mm for 90%-100%, 9.5mm for 50%-75%, 4.75mm for 20%-34%, 2.36mm for 15%-26%, 1.18mm for 14%-24%, 0.6mm for 12%-20%, 0.3mm for 10%-16%, 0.15mm for 9%-15% and 0.075mm for 8%-12%.

[0008] Preferably, on the basis of the above technical scheme, the aggregate is composed of first gravel, second gravel, third gravel, stone chips and mineral powder, the particle size range of the first gravel is 10-15mm, the particle size range of the second gravel is 5-10mm, the particle size range of the third gravel is 3-5mm and the particle size range of the stone chips is 0-3mm.

[0009] More preferably, the components of the aggregate are respectively 20%-30% of the first gravel, 19%-25% of the second gravel, 8%-18% of the third gravel, 35%-40% of the stone chips and the balance of the mineral powder.

[0010] More preferably, the mass percentage of the mineral powder is not more than 3%.

[0011] Preferably, on the basis of the above technical scheme, the pavement material further comprises asphalt, and the mass ratio of the aggregate to the asphalt is 18-21.

[0012] More preferably, the pavement material is AC-13 asphalt concrete.

[0013] More preferably, the asphalt is base asphalt.

[0014] The pavement material of the present application has the following beneficial effects relative to the prior art:

[0015] The present application can provide AC material with noise reduction performance not inferior to that of conventional SMA material by adjusting the proportion of each gradation of the aggregate, and can keep the noise reduction performance from fluctuating sharply with temperature change and maintain excellent low-temperature tensile capacity in an environment with large diurnal temperature difference, so that the pavement material can be widely used in arid regions with little rain and has relatively low cost. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of the present application.

[0017] Embodiment one

[0018] The pavement material of the present application is AC-13 asphalt concrete, which comprises aggregate and asphalt.

[0019] Among them, the asphalt concrete has multiple types according to the particle size classification of the aggregate of the asphalt mixture, among which the two most common types are AC-13 and SMA-13; AC-13 belongs to fine-grained asphalt concrete, and its corresponding types are AC-16 or AC-19 (medium-grained asphalt concrete), AC-26 or AC-31 (coarse-grained asphalt concrete), and among them, 13, 16, 19, 26, and 31 represent different maximum particle sizes; therefore, AC-13 is an asphalt category with a maximum particle size of 13.2 millimeters (mm).

[0020] The aggregate is a general term for various sizes of sand and stone particles in concrete, and when the aggregate is put into a screen with different mesh hole diameters, the mass percentage of the aggregate total weight that the sand and stone particles of different sizes can pass through the corresponding mesh hole diameter is called the gradation of the aggregate. If the gradation of the aggregate is not properly selected, the specific surface area and void ratio of the aggregate are too large, more cement paste is needed to make the concrete have a certain fluidity and to fill the voids between the aggregate; according to research, the amount of cement paste in the concrete is proportional to the void ratio of the aggregate. Moreover, the gradation of the aggregate has a great influence on the performance of hardened concrete, such as strength, durability, etc. If the aggregate gradation is unreasonable, even if more cement is added, the performance of the hardened concrete will also be affected to a certain extent, so the aggregate gradation is very important for obtaining high-quality and low-cost concrete. It can be seen that the aggregate gradation, the maximum particle size and the minimum particle size of the aggregate, etc. have a great influence on the cement consumption and water demand of the concrete, and also have a significant impact on the workability, pumpability, economy, porosity, shrinkage and durability of the concrete.

[0021] In this embodiment, the aggregate includes nine gradations, and the nine gradations are in the order of 13.2 mm for 95%, 9.5 mm for 62.5%, 4.75 mm for 27%, 2.36 mm for 20.5%, 1.18 mm for 19%, 0.6 mm for 16%, 0.3 mm for 13%, 0.15 mm for 12%, and 0.075 mm for 10% according to the particle size of the aggregate from large to small.

[0022] It should be noted that when designing the gradation of the aggregate, each gradation is usually designed according to the ideal synthetic gradation of the application scenario; but when the actual proportion of the aggregate is performed, the actual gradation of the aggregate is associated with the mass percentage of each component of the aggregate, and the ideal gradation usually cannot be achieved; since the mass percentage of each component of the aggregate is usually a range value, the upper limit and the lower limit of the gradation can be determined according to the range value, for example, in this embodiment, the upper limit of the gradation of 13.2 mm is 100%, and the lower limit is 90%, and then the actual gradation is taken as the median value of the gradation, which is 95%. In summary, the gradation design of the concrete aggregate is a mature technology in the art, and since the purpose of the case is not to improve the gradation design method, the specific process and principles for obtaining the gradation of the embodiment are not described in detail.

[0023] In addition, the AC-13 material of the embodiment is more accurately an AC-13C material, which belongs to a reclassification based on the AC-13 material. The reclassification is a classification with 2.36 mm as the key sieve size passing rate, and AC-13C refers to a key sieve passing rate of less than 40%, so it is an AC-13 coarse dense gradation; and another AC-13F refers to a key sieve passing rate of more than 40%, so it is an AC-13 fine dense gradation.

[0024] According to the specific material components, the aggregate is composed of a first kind of gravel, a second kind of gravel, a third kind of gravel, stone chips and mineral powder; the first kind of gravel, the second kind of gravel and the third kind of gravel refer to gravels of different particle sizes. The proportions of the components of the aggregate in different concrete are different, and the proportions of the components of the embodiment are 30%, 19%, 8%, 40% and 3% respectively according to the mass percentage.

[0025] The particle size range of the first kind of gravel is 10-15 mm, and the mass percentage is 30%.

[0026] The particle size range of the second kind of gravel is 5-10 mm, and the mass percentage is 19%.

[0027] The particle size range of the third kind of gravel is 3-5 mm, and the mass percentage is 8%.

[0028] The particle size range of the stone chips is 0-3 mm, and the mass percentage is 40%.

[0029] The balance is mineral powder; usually the mass percentage of the mineral powder is not more than 3%.

[0030] Usually, the asphalt used in AC asphalt concrete can be base asphalt or modified asphalt. However, the asphalt component in the embodiment uses base asphalt; the aggregate and the asphalt have a mass ratio of 18.8.

[0031] Both base asphalt and modified asphalt belong to asphalt materials, but there are some differences between them. Base asphalt is a petroleum by-product refined by heating, removing impurities and increasing viscosity to meet the requirements of different grades. Modified asphalt is a kind of modified variety of base asphalt by adding external additives to improve the performance of asphalt. Generally speaking, the performance of base asphalt is limited, and environmental factors such as sunlight, heat and humidity will affect the thermal stability and aging performance of asphalt, making it difficult to meet the requirements of road and other engineering purposes. Therefore, modified asphalt has been developed to meet the increasing engineering requirements. The additives of modified asphalt include various materials such as polymers, rubber powder and asphalt plasticizer, and the composition of additives varies with different manufacturers and products. The amount of modified asphalt is determined according to its needs and the balance of the performance of the composite material. In summary, base asphalt and modified asphalt are two different types of asphalt materials, and modified asphalt can be considered as an improved variety of base asphalt by adding additives to improve its performance. Each type of asphalt has its own unique advantages and disadvantages, and the actual needs and environmental factors should be considered when using it.

[0032] As mentioned earlier, the purpose of the present case is to provide a kind of asphalt concrete pavement material specially used in the arid and less-rainy areas. More specifically, the arid and less-rainy areas referred to in the present case mainly refer to the plateau areas in the northwest of China. In addition to being arid and less-rainy, these areas are located in the plateau, with large diurnal temperature difference, and the lowest pavement temperature at night can reach -20℃, while the pavement temperature at noon in summer is usually not lower than 40℃.

[0033] In order to meet the special environmental requirements of this area, SMA material is generally used as concrete pavement material for road construction. The difference between SMA material and AC material is that the asphalt used in SMA material must be modified asphalt. At the same time, SMA material components also include fiber, mainly wood fiber. At the same time, according to industry regulations, the gradation requirements of SMA material are different from those of AC material. SMA material is discontinuous gradation, while AC material is continuous gradation. Compared with conventional AC material, SMA material has better aging resistance, durability, pavement noise reduction performance and pavement crack resistance caused by temperature difference, so that the pavement is more durable and weather-resistant, and the service life of the pavement can be prolonged.

[0034] The SMA material also has many problems: firstly, the SMA material must use modified asphalt, and the additive composition and addition amount of the modified asphalt need to be determined according to its needs and the balance of the performance of the composite material, that is, the performance of the modified asphalt will be affected by the additives of different manufacturers and the actual road surface environment, which may result in different performance effects when the modified asphalt of the same component ratio of different manufacturers is applied to the same road surface environment, and the same component ratio of the modified asphalt of the same manufacturer may not be suitable for different road surface environments in the same area; secondly, the SMA material is discontinuous gradation, and the temperature difference between day and night is large in the northwest plateau area, which will cause the gap between different gradations of the aggregate to change greatly; such changes have a great influence on the noise reduction effect of the pavement material, and the addition of noise reduction powder in the modified asphalt or the use of rubber modified asphalt to improve the noise reduction performance not only leads to complex pavement material preparation, but also has high cost.

[0035] However, the noise reduction performance of the AC-13 material provided in the present case is not inferior to that of the SMA material, and since matrix asphalt is used, the application range is wider and the cost is lower. The gradation parameters of the AC-13 material of the present case and the gradation parameters of the conventional AC-13 material are compared in Table 1 below.

[0036] Table 1

[0037]

[0038]

[0039] According to Table 1, it can be found that the mass percentages of four gradations 0.6 mm, 0.3 mm, 0.15 mm and 0.075 mm in the present embodiment are relatively high compared with the conventional AC material. According to the applicant's long-term research, it is guessed that the reason for the improved noise reduction performance of the present embodiment is that the noise reduction mechanism is mainly due to the hindering effect of coarse and fine aggregate on sound wave propagation. When the sound wave propagates and collides in the particle pores, it will scatter in different directions, thereby converting part of the mechanical energy into other forms of energy absorbed by the mixture, resulting in energy attenuation to achieve sound absorption and noise reduction capacity. In the present embodiment, the gap between the large particle materials in the aggregate mixture is large, and the small particles use continuous gradation and have more gradation levels, so that the particles of different gradations are sequentially filled in the gap between the particles of the previous gradation, so that the material forms a structure similar to a porous material, thereby having good energy scattering performance. At the same time, since the present embodiment is applied in a dry and rainy area, the environmental humidity is low, even if the temperature difference between day and night in this area is large, the gap between the particles changes greatly, but the particle gap will not be filled with water vapor and other substances due to factors such as humidity, so that the formed porous material has good sound absorption and noise reduction capacity.

[0040] The present case adopts the SMA material in the industry grading table to grade the median value through the tire drop method to conduct noise comparison test, and the obtained data is shown in Table 2.

[0041] grading average noise value (decibel db) sma-13 grading median 38.91 the present embodiments 35.55

[0042] Through the test, it can be found that the noise reduction performance of the present embodiment is slightly better than that of the conventional SMA-13 material.

[0043] The present embodiment and the above SMA material are respectively subjected to comparison test through the tire drop method in the noon high temperature environment (40℃), the midnight low temperature environment (-10℃) and the room temperature environment (28℃), and the obtained data is shown in Table 3.

[0044] Table 3

[0045]

[0046]

[0047] Through the test, it can be found that the noise reduction performance of the present embodiment is still slightly better than that of the conventional SMA-13 material in the high temperature environment and the low temperature environment. It can also be found that the noise reduction performance of the present embodiment does not change dramatically with the temperature change

[0048] The present embodiment and the above SMA material are respectively subjected to low temperature crack resistance test through the semi-circular bending test method in the night low temperature environment 0℃, -10℃ and -20℃, and the obtained data is shown in Table 4.

[0049] Table 4

[0050]

[0051] Through the test, it can be found that the present embodiment has good crack resistance in the low temperature environment.

[0052] Embodiment Two

[0053] The present embodiment obtains the upper limit value of each grading compared with embodiment one.

[0054] Among them, 13.2mm is 100%, 9.5mm is 75%, 4.75mm is 34%, 2.36mm is 26%, 1.18mm is 24%, 0.6mm is 20%, 0.3mm is 16%, 0.15mm is 15% and 0.075mm is 12%.

[0055] Embodiment Three

[0056] The present embodiment obtains the lower limit value of each grading compared with embodiment one.

[0057] 13.2mm is 90%, 9.5mm is 50%, 4.75mm is 20%, 2.36mm is 15%, 1.18mm is 14%, 0.6mm is 12%, 0.3mm is 10%, 0.15mm is 9% and 0.075mm is 8%.

[0058] The noise comparison test of examples one to three shows that the average noise value of example two is 53.48db, the average noise value of example three is 67.25db, and therefore the aggregate and asphalt ratio of example one is the optimal solution for road surface material.

[0059] Example four

[0060] In this example, the aggregate and asphalt ratio is 18.

[0061] Example five

[0062] In this example, the aggregate and asphalt ratio is 20.3.

[0063] Example six

[0064] In this example, the aggregate and asphalt ratio is 21.

[0065] The noise comparison test of examples four to six shows that the average noise value of example four is 56.73db, the average noise value of example five is 37.82db, and the average noise value of example six is 62.12db, and therefore the aggregate and asphalt ratio of example one and example five are the optimal solution for road surface material.

[0066] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A pavement material, characterized by: The pavement material is AC-13 asphalt concrete, which comprises aggregate and asphalt, the aggregate is nine gradations, the nine gradations are in turn 13.2mm 95%, 9.5mm 62.5%, 4.75mm 27%, 2.36mm 20.5%, 1.18mm 19%, 0.6mm 16%, 0.3mm 13%, 0.15mm 12% and 0.075mm 10% according to the aggregate particle size from large to small, the definition of the gradation is that the aggregate is put into the screen with different mesh aperture, and the mass percentage of the aggregate total weight is the mass percentage of the sand and stone particles with different sizes which can pass through the corresponding mesh aperture; The aggregate is composed of first kind of gravel, second kind of gravel, third kind of gravel, stone chips and mineral powder, the particle size range of the first kind of gravel is 10-15mm, the particle size range of the second kind of gravel is 5-10mm, the particle size range of the third kind of gravel is 3-5mm, and the particle size range of the stone chips is 0-3mm; The components of the aggregate are respectively first kind of gravel 30%, second kind of gravel 19%, third kind of gravel 8%, stone chips 40% and the rest is mineral powder, the mass percentage of the mineral powder is not more than 3%; The aggregate and asphalt are in the mass ratio of 18-21, and the asphalt is base asphalt.

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