Method for evaluating durability of prime coat

Abstract

To provide a method for evaluating the performance of a prime coat.SOLUTION: Filling a mold with a roadbed material to form a roadbed material layer, applying or spraying a prime coat material on the formed roadbed material layer to form a prime coat, and laying at least two or more blocks on the formed prime coat; The method for evaluating the durability of a prime coat includes a step of forming a block-shaped upper layer, and a step of repeatedly applying a vertical load to at least two or more adjacent blocks among blocks constituting the upper layer after pouring water into a form, wherein the durability of the prime coat is evaluated based on the presence and / or the degree of sand blowout from a roadbed material layer in the step of repeatedly applying the load.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for evaluating the durability of a prime coat. [Background technology]

[0002] In paving work, after the roadbed is finished, a bituminous material such as cutback asphalt, asphalt emulsion, or straight asphalt is spread on the surface of the roadbed. The coating formed in this way is called a prime coat.

[0003] The applied bitumen penetrates the roadbed, stabilizing it. It also forms a coating of bitumen on the surface of the roadbed, making it easier for the asphalt mixture layer to adhere to. Furthermore, because bitumen is impervious to moisture, the primed roadbed is protected from erosion by rain.

[0004] Long-standing experience in this technical field has shown that applying a prime coat provides the above-described roadbed protection effect. However, to the inventors' knowledge, there is no known method for directly evaluating the effects that a prime coat is said to provide. Furthermore, there is no common effort to evaluate the performance of prime coats obtained using prime coat materials and select an appropriate prime coat for each paving site.

[0005] The standards for asphalt emulsions for prime coats are set forth in the Japanese Industrial Standards and the Japan Asphalt Emulsion Association Standards. For example, the Japanese Industrial Standard JIS K2208:2000 specifies various physical properties of asphalt emulsions for prime coats (PK-3), such as Engler degree, sieve residue, adhesion, and evaporation residue. Furthermore, the Japan Asphalt Emulsion Association Standard JEAAS2006 specifies various physical properties, such as Engler degree, sieve residue, adhesion, and evaporation residue, as well as permeability standards, for high-penetration asphalt emulsions for prime coats (PK-P). However, these standards do not directly specify the performance of prime coats in protecting the roadbed.

[0006] Even in patent documents related to prime coats, the only indicator used to evaluate whether an asphalt emulsion functions as a prime coat is its permeability into the roadbed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Unexamined Patent Publication No. 56-011965 Summary of the Invention [Problem to be solved by the invention]

[0008] At each paving site, the wheel load and frequency of wheel load on the pavement vary, and therefore the performance required of the prime coat also varies. If it were possible to evaluate the durability of the prime coat formed using various materials for the prime coat, it would be possible to select the prime coat appropriate for each site, which would contribute to extending the life of the pavement and efficiently using paving materials. However, as explained above, there appears to be a lack of a reliable method for evaluating the performance of the prime coat in this technical field.

[0009] The present invention has been made in view of the problems of the prior art in this technical field, and an object of the present invention is to provide a method for evaluating the performance of a prime coat. [Means for solving the problem]

[0010] It is known that cracked pavements can rapidly deteriorate the stability of the subgrade due to the deterioration of the prime coat, as evidenced by the frequent problem of sand boiling caused by pumping in cracked pavements.

[0011] Cracked pavements allow rainwater and other water to easily penetrate into the pavement from the surface. When traffic loads act on a pavement with water seeping into the roadbed, causing the asphalt mixture and concrete layers above the roadbed to flex, pressure is exerted on the water inside the pavement, forcing it out of the cracks. If the prime coat is damaged and the stability of the roadbed is compromised, fine particles that make up the roadbed will also be ejected from the cracks along with the water. This is known as sand boiling due to pumping. When sand boiling due to pumping occurs, the fine particles that make up the roadbed are lost, creating voids within the roadbed, significantly reducing the roadbed's bearing capacity and making it more susceptible to further structural failure.

[0012] As mentioned above, one of the purposes of applying Prime Coat is to protect and stabilize the roadbed. In roadbeds where sand boiling due to pumping is observed, the Prime Coat is not adhering the roadbed material, and it is thought that the Prime Coat's ability to stabilize the roadbed has decreased.

[0013] The inventors of the present invention have focused on the cracks in pavement and the structural damage to the roadbed caused by the cracks, and as a result of extensive research, have found that the durability of the prime coat can be efficiently evaluated by using the sand boiling caused by pumping as an indicator. A step of filling the formwork with roadbed material to form a roadbed material layer; A step of applying or spraying a prime coat material on the formed roadbed material layer to form a prime coat; a step of laying at least two or more blocks on the formed prime coat to form a block-shaped upper layer; After pouring water into the formwork, repeatedly applying a vertical load to at least two or more adjacent blocks among the blocks constituting the upper layer; Including, The durability of the prime coat is evaluated based on the presence or absence and / or degree of sand boiling from the roadbed material layer during the process of repeatedly applying a load. The present invention solves the above problems by providing a method for evaluating the durability of a prime coat, characterized by: [Effects of the Invention]

[0014] According to the present invention, the durability of a prime coat formed using various prime coat materials can be efficiently and simply evaluated. [Brief explanation of the drawings]

[0015] [Figure 1] This figure shows the number of times a load of (a) 17 kN or (b) 49 kN was repeatedly applied at a frequency of 1 Hz until sand boiling began. [Figure 2] This figure shows the amount of fine particles ejected after repeatedly applying a load of (a) 17 kN or (b) 49 kN at a frequency of 1 Hz 5,000 times. [Figure 3] FIG. 1 shows the amount of settlement after a load of (a) 17 kN or (b) 49 kN was repeatedly applied 5,000 times at a frequency of 1 Hz. [Figure 4] FIG. 1 is a diagram showing the procedure of an evaluation method according to an embodiment of the present invention. [Figure 5] FIG. 1 is a diagram showing an overview of an evaluation method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, the method for evaluating the durability of a prime coat according to the present invention will be described in more detail for each step.

[0017] <The process of filling the formwork with roadbed material and forming the roadbed material layer> In the evaluation method according to the present invention, first, a roadbed material is filled into a formwork to form a roadbed material layer.

[0018] "Road base material" refers to a material that constitutes a road base. The road base material may basically be any material that is used to constitute a road base, and there are no particular restrictions on the type, but it may preferably be a granular road base material. The granular road base material is a granular road base material, and may be, for example, crushed stone such as cut crushed stone (crushed run) and size-adjusted crushed stone; gravel such as cut gravel and mountain gravel; sand; steel slag road base materials such as crushed steel slag for road base, crushed run steel slag, and size-adjusted steel slag; recycled road base materials such as recycled crushed run and recycled size-adjusted crushed stone, and mixtures thereof, but is not limited to these.

[0019] There is no particular limit to the amount of roadbed material filled into the formwork, but it is preferable that the amount be such that the thickness of the roadbed material layer formed inside the formwork is within the range of 50 mm to 300 mm.

[0020] The roadbed material filled into the formwork may be compacted as necessary. That is, in a preferred embodiment, the evaluation method according to the present invention may further include a step of compacting the filled roadbed material after filling the formwork with the roadbed material. Basically, any method of compaction may be used, and there are no particular limitations on the specific method. For example, compaction may be performed using a machine such as a tamper or rammer, or may be performed using a tool such as a compacting rod or compaction bar. If possible, compaction may be performed using a vibrating roller, a tire roller, or the like. There are no particular limitations on the degree of compaction, but the degree of compaction is preferably, for example, 90 to 100%.

[0021] In a preferred embodiment, the roadbed material layer may be composed of multiple layers. For example, the roadbed material layer may have a two-layer structure consisting of an upper roadbed material layer and a lower roadbed material layer. In this case, the multiple roadbed material layers may be composed of different roadbed materials and may be compacted to different degrees of compaction.

[0022] The formwork into which the roadbed material is filled can basically be any type as long as it can be filled with the roadbed material, and there are no particular restrictions on its size or shape. In the evaluation method according to the present invention, water is poured into the formwork during the test, so it is preferable that the formwork does not leak the poured water.

[0023] <Process of applying or spraying a prime coat material onto the roadbed material layer to form a prime coat> In the evaluation method according to the present invention, next, a prime coat material is applied or sprayed onto the roadbed material layer formed within the formwork, thereby forming a prime coat.

[0024] The prime coat material applied or sprayed onto the roadbed material layer is a prime coat material, and can be essentially any material that is considered for use as a prime coat material. However, it can typically be a bituminous material such as straight asphalt, cutback asphalt, modified asphalt, or asphalt emulsion. The asphalt emulsion can also be a modified asphalt emulsion containing modifying components such as resin or rubber. There are also no particular restrictions on the type of emulsifier contained in the asphalt emulsion, and it can be any of cationic asphalt emulsion, anionic asphalt emulsion, and nonionic asphalt emulsion.

[0025] There are no particular limitations on the specific method for applying or spraying the prime coat material to the roadbed material layer, and a person skilled in the art can apply or spray the prime coat material by an appropriate method. To give an example, the prime coat material may be applied or sprayed on the surface of the roadbed material layer by a spray or a brush.

[0026] After the prime coat material is applied or sprayed onto the roadbed material layer, it may be allowed to cure for a predetermined period of time. There is no particular limit to the curing time, and an appropriate curing time may be adopted depending on the type and / or amount of the prime coat material used. To give an example, after the prime coat material is applied or sprayed onto the roadbed material layer, it may be allowed to cure for 1 hour or more, 3 hours or more, or 6 hours or more.

[0027] There is no particular limitation on the amount of prime coat material applied or sprayed on the roadbed material layer, but for example, 0.1 to 3.0 kg / m 2 , preferably 0.2 to 2.5 kg / m 2 , more preferably 0.5 to 2.0 kg / m 2 , and more preferably 1.0 to 1.5 kg / m 2 In this specification, when a numerical range is indicated using "to," it means that the numerical range includes the upper and lower limits, unless otherwise specified.

[0028] If necessary, other components may be applied or sprayed onto the roadbed material layer in addition to the prime coat material. Such components may include, but are not limited to, a decomposition accelerator that accelerates the decomposition of the asphalt emulsion, a hardener that accelerates the hardening of the asphalt emulsion, and the like.

[0029] In a preferred embodiment, the upper surface of the roadbed material layer, i.e., the contact area where the edge of the prime coat surface and the formwork come into contact, may be sealed with a waterproof sealant. In other words, in a preferred embodiment, the evaluation method according to the present invention may further include a step of sealing the contact area where the edge of the prime coat surface and the formwork come into contact with a waterproof sealant. The sealant may be essentially any material that is waterproof or adhesive to the prime coat and the formwork, but may be, for example, asphalt. By sealing the contact area where the edge of the prime coat surface and the formwork come into contact with a waterproof sealant, water penetration and the outflow of fine particles that do not pass through the prime coat are suppressed, thereby enabling more accurate evaluation of the durability of the prime coat.

[0030] <The process of laying at least two blocks on the prime coat to form a block-shaped upper layer> This is the process of laying at least two blocks on the prime coat formed on the roadbed material layer to form a block-shaped upper layer. This upper layer simulates the upper layers, such as the base and surface layers, that will be constructed on top of the prime coat at the paving site. In addition, the upper layer is made up of at least two blocks to simulate cracks.

[0031] The blocks laid on the prime coat may be made of any material, but are preferably made of materials that will form the base and surface layers that will be laid on top of the prime coat at the paving site. Examples of such materials include asphalt mixtures and / or cement concrete. Those skilled in the art can prepare blocks of a predetermined shape made of asphalt mixtures and / or cement concrete using an appropriate method.

[0032] There are no particular restrictions on the shape of the blocks laid on the prime coat, but a rectangular parallelepiped or cubic shape is preferred. There are no particular restrictions on the dimensions, but from the perspective of stable installation on the prime coat applied to the roadbed material layer, if the blocks are rectangular parallelepiped or cubic, their width and depth are preferably 30 mm or more, more preferably 40 mm or more. Furthermore, from the perspective of preventing damage to the blocks during the loading process, their thickness (height) is preferably 30 mm or more, more preferably 40 mm or more. Note that it is preferable that the thickness (height) of each block is substantially the same. This is because if the thickness (height) of each block differs, it may be difficult to simultaneously load at least two or more adjacent blocks.

[0033] The number of blocks laid on the prime coat is not particularly limited, as long as it is at least two or more. For example, it can be three, four, five, six, seven, eight, nine, ten, or more. As shown in the experimental example described below, it can be as many as 14 in total. The more blocks laid, the more fine cracks can be reproduced.

[0034] The blocks laid on the prime coat are preferably laid densely on the prime coat. Here, "laid densely" means that, when the blocks are laid, the spacing between adjacent blocks is within the range of 0.5 to 5 mm, preferably 0.6 to 4 mm, more preferably 0.7 to 2 mm, and even more preferably 0.8 to 1.5 mm. If the spacing between adjacent blocks is too large, it may be difficult to simultaneously load adjacent blocks. On the other hand, if the spacing between adjacent blocks is too small, it may be difficult to lay and remove the blocks, and it may be difficult to detect fine sand boiling.

[0035] <The process of pouring water into the formwork> In the evaluation method according to the present invention, in order to reproduce the condition of a roadbed that is excessively wet during rainfall, water is poured into the formwork before a load is applied to the blocks that make up the upper layer.

[0036] The water poured into the formwork may be basically any type of water, such as rainwater, tap water, seawater, river water, etc. It may also be pH-adjusted water that simulates acid rain.

[0037] There is no particular limitation on the amount of water poured into the formwork, but the water level in the formwork may be, for example, 1 mm or more, preferably 3 mm or more, more preferably 5 mm or more, and even more preferably 10 mm or more from the top surface of the prime coat, based on the top surface of the prime coat. More preferably, the water level in the formwork may be, for example, 1 mm or more, more preferably 3 mm or more, more preferably 5 mm or more, and even more preferably 10 mm or more from the top surface of the block constituting the upper layer, based on the top surface of the block.

[0038] This is a process in which a vertical load is repeatedly applied to at least two or more adjacent blocks of the upper layer. In this process, a vertical load is simultaneously applied to at least two or more adjacent blocks of the upper layer. This reproduces the load that is applied to the prime coat and subgrade layer through a crack in the pavement when a vehicle passes through the crack.

[0039] The vertical direction refers to the direction perpendicular to the top surface of the roadbed material layer to which the prime coat has been applied (i.e., the prime coat surface), and more specifically, refers to the direction along the Z axis when the top surface of the roadbed material layer to which the prime coat has been applied (the prime coat surface) is taken as the XY plane. Here, when referring to the vertical direction, an error of ±5° with respect to the Z axis is acceptable unless otherwise specified.

[0040] There are no particular limitations on the magnitude of the load to be applied, but typically, a load equivalent to the traffic load expected to be applied to the pavement should be applied. For example, it may be 49 kN, the standard wheel load for a normal road, or 17 kN, the standard wheel load for a small road, but is not limited to these. Furthermore, the magnitude of the applied load does not necessarily have to be constant; a combination of two or more different loads may be applied.

[0041] There is no particular limitation on the frequency of loading, that is, the loading frequency, but it can be, for example, within the range of 0.1 Hz to 10 Hz, 0.5 Hz to 5 Hz, or 1 to 2 Hz.

[0042] There is no particular limit to the number of times loading is performed, and an appropriate number of times loading can be selected depending on the durability of the prime coat, for example, within the range of 10 to 100,000 times, 100 to 20,000 times, or 1,000 to 10,000 times.

[0043] There are no particular limitations on the waveform of the load, and an appropriate waveform can be selected depending on the traffic load to be simulated. For example, waveforms such as a sine wave, a haversine wave, a triangular wave, and a square wave can be used, but are not limited to these. From the perspective of simulating the waveform of the load applied to the pavement on site, a haversine wave can be preferably used.

[0044] There are no particular limitations on the specific loading method as long as it is possible to repeatedly apply a vertical load to at least two adjacent blocks, but for example, a commercially available mechanical testing machine can be suitably used, as shown in the experimental examples described below. Note that in this technical field, mechanical testing machines are also called compression testing machines, universal compression testing machines, load testing machines, and fatigue / endurance testing machines.

[0045] <Process for evaluating the durability of the prime coat> This is a process for evaluating the durability of the prime coat based on the presence or absence and / or degree of sand boiling from the roadbed material layer. In a roadbed material layer with a sound prime coat, the roadbed materials that make up the roadbed material layer are bonded and stabilized to each other, and sand boiling from the roadbed material layer is suppressed. Therefore, the presence or absence and / or degree of sand boiling from the roadbed material layer when repeatedly loaded a predetermined number of times reflects the soundness of the prime coat and its durability against repeated loading.

[0046] "Sand boiling" refers to the ejection of fine particles such as sand that make up the roadbed material from the roadbed material layer, and more specifically, the ejection of fine particles such as sand that make up the roadbed material from the roadbed material layer above the prime coat. As shown in the experimental example described below, sand boiling from the roadbed material layer can be observed as a phenomenon in which fine particles are ejected from gaps between blocks.

[0047] The presence or absence and / or extent of sand boiling can be determined, for example, based on the number of loadings performed before sand boiling begins. As described above, when the prime coat is sound, the roadbed materials that make up the roadbed material layer are bonded and stabilized to each other, suppressing sand boiling from the roadbed material layer. In contrast, if the prime coat is damaged, the roadbed material will no longer be able to withstand the water pressure caused by repeated loading, and fine particles will be ejected above the prime coat surface. Therefore, the number of loadings performed before sand boiling begins reflects the soundness of the prime coat and its durability against repeated loading. The more loadings performed before sand boiling begins, the higher the durability of the prime coat.

[0048] The number of loadings required until sand boiling starts can be confirmed visually, as shown in the experimental examples described below, or can be evaluated using a measuring device such as a turbidity meter. When sand boiling starts, the water in the formwork begins to become suspended, so the number of loadings required until sand boiling starts can be determined based on the start or degree of suspension of the water in the formwork. When visually checking the number of loadings required until sand boiling starts, it is preferable to observe from multiple angles. If necessary, the loading process can be recorded using video or the like, and the determination can be made based on the recorded video.

[0049] In a preferred embodiment, the presence and / or extent of sand boiling can be determined based on the amount of sand boiling obtained when loading is repeated a predetermined number of times. The amount of sand boiling obtained when loading is repeated a predetermined number of times can be determined by collecting the boiled sand contained in the water in the formwork after repeated loading a predetermined number of times, and, if necessary, collecting the boiled sand attached to each block or formwork, and measuring the weight of the collected boiled sand. There are no particular restrictions on the method for collecting the boiled sand, but the boiled sand contained in the water in the formwork can be collected, for example, using a suction pump. Furthermore, the boiled sand attached to the blocks or formwork can be collected by rinsing the blocks or formwork with water and collecting the washed water.

[0050] There is no particular limit to the predetermined number of times, i.e., the number of loadings before measuring the amount of sand boiling, but it can be within the range of, for example, 10 to 100,000 times, 100 to 50,000 times, or 1,000 to 10,000 times. If the amount of sand boiling is small or no sand boiling is observed, the number of loadings can be increased, and if the amount of sand boiling is too large, the number of loadings can be decreased. In addition, the amount of sand boiling after multiple loadings can be measured, and the relationship between the amount of sand boiling and the number of loadings can be determined and used as an index of the durability of the prime coat.

[0051] In a preferred embodiment, the presence or absence and / or extent of sand boiling can be determined based on the amount of subsidence of the roadbed material layer when loading is repeated a predetermined number of times. As the amount of sand boiling from the roadbed material layer increases, voids are generated in the roadbed material layer, making the roadbed material layer more likely to subside. Therefore, the amount of subsidence of the roadbed material layer reflects the degree of sand boiling.

[0052] The amount of settlement of the roadbed material layer can be measured, for example, by a position sensor attached to the loading plate of a mechanical testing machine, as shown in the experimental examples described below. However, the method for measuring the amount of settlement of the roadbed material layer is not limited to this, and it can be measured by any appropriate method. For example, the height of the roadbed material layer can be measured using a ruler or tape measure before and after the test.

[0053] The predetermined number of times, i.e., the number of times of loading before the amount of subsidence is measured, is the same as that described for the number of times of loading before the amount of sand boiling is measured.

[0054] According to the evaluation method of the present invention described above, the durability of the prime coat can be evaluated based on the presence or absence and / or degree of sand boiling from the roadbed material layer. The durability of the prime coat evaluated here can be specifically the durability of the prime coat's ability to stabilize the roadbed, and more specifically, the durability of the prime coat's ability to stabilize the roadbed in a cracked pavement.

[0055] <Experimental Example> The present invention will be described in more detail below based on examples, but it goes without saying that the present invention is not limited to the examples.

[0056] 1. Test Method A schematic diagram of one embodiment of the method of the present invention, described below, is shown in Figure 4. First, crushed stone (roadbed material) with a median particle size of M-30, as specified in JIS A5001, was placed in a formwork with internal dimensions of 300 mm wide x 360 mm deep x 250 mm high, and compacted using a vibrating tamper. The amount of crushed stone was determined so that the thickness of the roadbed material would be 100 mm when compacted to a compaction degree of 95% at the optimal moisture content. This resulted in a 100 mm thick granular roadbed layer being created within the formwork.

[0057] Next, the granular roadbed layer formed by the above procedure was applied with a prime coat material at 1.0 kg / m 2 The prime coat was formed by spraying the mixture at a spray rate of 1000 mg / kg and curing it at room temperature for 6 hours. The prime coat material used was an asphalt emulsion that meets the PK-3 standard for asphalt emulsion for prime coats specified in the Japanese Industrial Standard JIS K2208:2000 (hereinafter simply referred to as "PK-3") or an asphalt emulsion that meets the PK-P standard for high-penetration asphalt emulsion for prime coats specified in the Japan Asphalt Emulsion Association Standard JEAAS2006 (hereinafter simply referred to as "PK-P").

[0058] After six hours of curing, heated asphalt (product name: Fresh Coat, manufactured by Nichireki Co., Ltd.) was applied to the surface of the granular roadbed layer, i.e., the boundary between the formwork and the edge of the prime coat surface, to seal the gap between the formwork and the granular roadbed layer.

[0059] Next, four concrete blocks measuring 100mm wide x 100mm deep x 60mm high were placed in the center of the prime coat surface, and four concrete blocks measuring 100mm wide x 47-50mm deep x 60mm high, and six concrete blocks measuring 75-80mm wide x 95-100mm deep x 60mm high were placed around them to form a block-shaped upper layer simulating a cracked upper layer. The spacing between each block was 0.9-1mm.

[0060] Next, water was poured into the formwork so that the water level was 10 mm above the top surface of the block.

[0061] Loading of the blocks was carried out using a fatigue and durability testing machine (product name: SERVOPULSER; model number: EHF-UV100K4-040SP; manufacturer: Shimadzu Corporation). Specifically, a circular loading plate with a diameter of 150 mm was placed at the center of four blocks laid in the center of the primed coat surface, and a vertical load was applied to the four blocks under the conditions shown in Table 1. During loading, the loading status was visually confirmed and videotaped from multiple angles to record the situation.

[0062] [Table 1]

[0063] The evaluation items were the following three items. <Number of loads until sand boiling begins> Sand boiling was defined as sand being blown up from the gaps between the blocks, and the number of loadings at which sand boiling began was determined by visual inspection during loading and by visual inspection of the recorded video. <Amount of fine particles ejected> After 5,000 loads, the suspended water in the formwork was sucked up using a suction pump until no puddles remained when the blocks were removed, and the suspended water containing the fine particles that had been ejected was collected. The fine particles adhering to each block were also washed away with water, and the water used for washing was collected. The collected suspended water and the water used for washing were dried in an oven at 110°C, and the weight of the remaining fine particles was measured, which was used as the amount of ejected fine particles. <Subsidence amount> The vertical displacement of the loading plate from the start to the end of the test was obtained from the position information of the loading plate output from the fatigue and durability testing machine, and this was taken as the amount of settlement.

[0064] 2. Test Results Figure 1 shows the number of loads required to suspend the water in the formwork. As shown in Figure 1a, when a 17-kN load, equivalent to the standard wheel load for a small road, was repeatedly applied, the water began to suspend after 180 loads for the specimen without a prime coat. In contrast, the number of loads required to suspend the water was 294 for the specimen primed with a permeable asphalt emulsion for prime coat (PK-3), and 700 for the specimen primed with a high-permeability asphalt emulsion for prime coat (PK-P). The number of loads required to suspend the water was greater for both the PK-3 and PK-P specimens than for the specimen without a prime coat. This result is thought to reflect the stabilization of the subgrade layer by the prime coat using PK-3 and PK-P. In particular, the number of loads required for the specimen primed with PK-P, a highly permeable asphalt emulsion, to begin to suspend was 700, a number greater than that required for the specimen primed with PK-3. This result suggests that, for the standard wheel load (17 kN) of small roads, highly permeable asphalt emulsions such as PK-P can provide particularly excellent roadbed protection performance.

[0065] On the other hand, as shown in Figure 1b, when a 49 kN load, equivalent to the standard wheel load for a regular road, was repeatedly applied, the unprimed specimen began to suspend water after 49 loads. In contrast, the specimen primed with PK-3 required 154 loads to suspend water, and the specimen primed with PK-P required 100 loads to suspend water. In both cases, the number of loads required to suspend water was greater than that required for the unprimed specimen. This result is thought to reflect the stabilization of the subgrade material layer by the prime coats using PK-3 and PK-P. In contrast to the standard wheel load (17 kN) for a small road, the specimen primed with PK-P, a highly permeable asphalt emulsion, required 100 loads to suspend water, a shorter number of loads required to suspend water compared to the specimen primed with PK-3. These results suggest that for the standard wheel load (49 kN) of ordinary roads, a more adhesive asphalt emulsion such as PK-3 may provide better roadbed protection performance than a more permeable asphalt emulsion such as PK-P.

[0066] Figure 2 shows the amount of ejected fine particles after 5,000 repeated loads of 17 kN or 49 kN at a frequency of 1 Hz. As shown in Figure 2a, when a 17 kN load, equivalent to the standard wheel load for a small road, was applied, the amount of ejected fine particles was 32.3 g for the unprimed specimen, 16.7 g for the specimen primed with PK-3, and 22.8 g for the specimen primed with PK-P. Also, as shown in Figure 2b, when a 49 kN load, equivalent to the standard wheel load for a regular road, was applied, the amount of ejected fine particles was 159.1 g for the unprimed specimen, 135.6 g for the specimen primed with PK-3, and 148.1 g for the specimen primed with PK-P.

[0067] In both cases, the amount of ejected fine particles was lower when prime coated with PK-3 or PK-P compared to specimens without a prime coat. This result is thought to reflect the stabilization of the roadbed material layer by the prime coat using PK-3 or PK-P. In particular, when a load of 49 kN, which corresponds to the standard wheel load on an ordinary road, was repeatedly applied, the difference in the amount of ejected fine particles between specimens with and without a prime coat was small, but this is thought to be due to the relatively high number of load cycles (5,000 times).

[0068] Figure 3 shows the settlement after 5,000 repeated loads of 17 kN or 49 kN at a frequency of 1 Hz. As shown in Figure 3a, when a 17 kN load, equivalent to the standard wheel load for small roads, was applied, the settlement for the unprimed specimen was 3.2 mm, the amount of ejected fine particles for the PK-3 primed specimen was 3.7 mm, and the amount of ejected fine particles for the PK-P primed specimen was 4.6 mm. When a 17 kN load, equivalent to the standard wheel load for small roads, was applied 5,000 times, there was little difference in settlement between the unprimed specimen and the PK-3 or PK-P primed specimen. This result is consistent with the above test results showing that the amount of ejected fine particles was small, even when a 17 kN load, equivalent to the standard wheel load for small roads, was applied 5,000 times.

[0069] On the other hand, as shown in Figure 3b, when a load of 49 kN, which corresponds to the standard wheel load on an ordinary road, was repeatedly applied, the amount of ejected fine particles for the specimen without a prime coat was 10.6 mm, the amount of ejected fine particles for the specimen prime coated with PK-3 was 6.7 mm, and the amount of ejected fine particles for the specimen prime coated with PK-P was 7.1 mm. Compared to the specimen without a prime coat, the amount of settlement was reduced when prime coated with PK-3 or PK-P. This result is thought to reflect the stabilization of the roadbed material layer by the prime coat using PK-3 or PK-P. [Industrial Applicability]

[0070] The method of the present invention makes it possible to evaluate the durability of various prime coat materials. If the durability of various prime coat materials can be known, it will be possible to select and design a prime coat that is suitable for each site. In this way, the present invention, which contributes to the efficiency of paving and the extension of paving life, has great industrial applicability.

Claims

1. A step of filling the formwork with roadbed material to form a roadbed material layer; A step of applying or spraying a prime coat material on the formed roadbed material layer to form a prime coat; a step of laying at least two or more blocks on the formed prime coat to form a block-shaped upper layer; a step of repeatedly applying a vertical load to at least two or more adjacent blocks among the blocks constituting the upper layer after pouring water into the formwork; Including, The durability of the prime coat is evaluated based on the presence or absence and / or degree of sand boiling from the roadbed material layer during the process of repeatedly applying a load. A method for evaluating the durability of a prime coat.

2. 2. The method of claim 1, wherein the blocks consist of asphalt mixture and / or cement concrete.

3. 3. The method according to claim 1 or 2, characterized in that the durability of the prime coat is evaluated based on the number of times a load is applied repeatedly in the process of applying a load until sand starts to boil from the roadbed material layer.

4. 3. The method according to claim 1, wherein the durability of the prime coat is evaluated based on the amount of sand blown out from the roadbed material layer during the step of repeatedly applying a load.

5. 3. The method according to claim 1, wherein the durability of the prime coat is evaluated based on the amount of settlement of the roadbed material layer during the step of repeatedly applying a load.

Images