JP2015178748A - Inspection method of recycled asphalt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method enabling quality of a recycled asphalt material to be quickly and comparatively easily inspected before used in pavement.SOLUTION: The inspection method of the present invention is an inspection method for inspecting quality of a recycled asphalt material obtained by adding a recycling additive to a used asphalt material and adjusting the temperature thereof to 140°C or more, before the recycled asphalt material is used for pavement. The inspection method includes: measuring at least one of a total amount of gas discharged from the recycled asphalt material or a part thereof within a certain period while the recycled asphalt material is kept at 140°C or more and reduction in mass of the recycled asphalt material or a part thereof caused within a certain period; and determining the quality of the recycled asphalt material based on the measurement result.

Description

  The present invention relates to a recycled asphalt material inspection method for inspecting the quality of recycled asphalt material before construction at a pavement construction site such as a road, for example.

  When the asphalt paved road deteriorates, the pavement material is peeled off from the roadbed and a new pavement material is laid. Degraded asphalt materials for roads managed by local governments other than expressways because there is not enough space to dispose of or temporarily store stripped pavement materials (hereinafter referred to as degraded asphalt materials) Must be reused for paving. At present, the usage rate of recycled materials has improved due to the spread and progress of recycled pavement technology, and recycled asphalt materials (hereinafter referred to as repeated recycled asphalt materials) that have been repeatedly recycled are also reused in pavement.

The standard values for pavement performance indicators are given in the Pavement Design and Construction Guidelines (December 2001) established by the Ministry of Land, Infrastructure, Transport and Tourism shown in Table 1. This guideline indicates the traffic volume (paved planned traffic volume) divided into seven grades N1 to N7 and the corresponding number of fatigue failure wheels as reference values for pavement performance indexes.

  Repeated reclaimed asphalt material is expected to deteriorate in quality because it is repeatedly used according to the cycle of pavement → removal → regeneration → pavement. However, at present, only the penetration estimation test, which is a measure of workability, is performed, and no other inspection is performed. For this reason, there is a frequent inconvenience that repeatedly recycled asphalt materials with poor quality that do not meet the pavement performance grade required for construction roads are brought into the field from the factory.

  Assuming that the quality of reclaimed asphalt material does not satisfy the performance grade of pavement required for roads, it is considerably shorter (for example, 1-2 years) than the service life (for example, 10 years) originally anticipated by the orderer. ) May cause defects such as cracks, depressions, and steps on the road surface. If such a defect occurs in a period shorter than the expected life of the road, the cause is the use of regenerated asphalt material with poor quality, and the contractor is responsible for the problem of construction. Is often passed on. This does not provide a true solution to the problem.

  Against this background, the industry is demanding to establish an inspection method for appropriately evaluating the quality of regenerated asphalt material before construction.

  As a conventional inspection method, Non-Patent Document 1 describes an asphalt penetration estimation test method (hereinafter referred to as a penetration penetration test method) for recycled aggregates by a Marshall stability test in accordance with JIS K2207. The penetration test method is an evaluation test method that is performed in a recycling plant before shipment of regenerated asphalt materials. In this evaluation test method, first, new asphalt (hereinafter referred to as new asphalt material) or new aggregate is mixed with deteriorated asphalt material, this mixture is crushed finely, and a regenerative additive containing an organic solvent is added thereto, followed by heating. Fill the mold in a soft state and compact it with a rammer. A specific needle is entered under specific conditions, and the hardness (softness) of the recycled asphalt material is estimated repeatedly from the needle entry distance.

  The quality of recycled asphalt is classified into three grades, “40-60”, “60-80”, and “80-100”, depending on the penetration (the penetration distance is 0.1 mm and the penetration is 1). Therefore, the quality of the repeatedly recycled asphalt material is judged based on the above grade. Recycled asphalt materials that have been judged to be acceptable are transported by truck from the recycling plant to the construction site and used for paving work under a certain temperature control.

“Pavement Test Method Handbook (provisional test method)”, October 20, 1996, first edition, first edition, issue place: Japan Road Association, pages 197-203

  Although the judgment result by the penetration test method serves as a measure of workability of asphalt pavement, it does not indicate the quality or performance of the repeatedly recycled asphalt material as a pavement material. In addition, since testing is not performed at the construction site, but is performed at the recycling factory or test inspection site, a test inspection method that can be performed at the construction site is also desired from the viewpoint of quality control and traceability. . And although a specific chemical substance is not used for the regeneration additive, there is no method for confirming that the specific chemical substance is not used at the construction site. For this reason, regenerated asphalt materials to which regenerated additives of poor quality such as waste oil are added may be brought into the field from the factory.

  When pavement work is performed using repeatedly recycled asphalt material with poor quality, various problems described below occur.

(1) Increase in environmental load During construction, organic solvents etc. volatilize in large quantities from the pavement surface and give off a bad odor, resulting in complaints from pavement workers and local residents.

(2) Early deterioration of pavement material After the construction, the deterioration of the pavement material is remarkably fast. For example, the pavement that expects a useful life of 10 years will be damaged, such as cracks, depressions, and steps in about one year from the construction. The damaged part must be repaired frequently.

(3) Pavement life is short This is related to (2) above, but it is impossible to cover with partial repairs, and it is necessary to re-pave the road where pavement has deteriorated completely in a shorter period than the initially expected life. There is.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an inspection method capable of quickly and relatively simply inspecting the quality of recycled asphalt material before use in pavement. .

  The inspection method according to the present invention is an inspection method for inspecting the quality of a regenerated asphalt material which has been added with a regenerated additive to a used asphalt material and whose temperature has been adjusted to 140 ° C. or higher before the regenerated asphalt material is used for pavement. The total amount of gas released from the regenerated asphalt material or a part thereof within a predetermined period while the temperature of the regenerated asphalt material is maintained at 140 ° C. or higher, and the regenerated asphalt material generated within the predetermined period or the same The method includes measuring at least one of a part of mass loss and judging the quality of the recycled asphalt material based on a result of the measurement.

  The important terms used in this specification are defined below.

  “Deteriorated asphalt material” refers to asphalt pavement material stripped off from roads and the like. In addition to national roads, prefectural roads, city roads, and other general roads, roads and the like include sites or roads with low traffic volume such as sidewalks, bicycle paths, communication paths, parking lots and bicycle parking lots.

  “Recycled asphalt material” means a recycled material that has been recycled by adding a regeneration additive to the pulverized deteriorated asphalt material, heating, stirring, and mixing, or this recycled material and a new aggregate It means an asphalt material mixed with a new material containing a filler and an asphalt composition. The ratio of the sum of the deteriorated asphalt material and the regenerated additive to the regenerated asphalt material is, for example, in the range of 5 to 100% by mass.

  “Repeatedly reclaimed asphalt material” refers to asphalt material that has been regenerated twice or more among regenerated asphalt materials.

  The “regenerated additive” refers to an additive that is added at the factory during the production of regenerated asphalt or repeated regenerated asphalt in order to restore the penetration characteristics of the deteriorated asphalt material. The regenerative additive is mainly composed of asphalt type and petroleum lubricating oil type, and some of them contain an organic solvent and asphaltenes as a part of the components. Examples of the oil include machine oil, saturated hydrocarbons (paraffin, naphthene, etc.), aromatic hydrocarbons (benzene, etc.) and the like. Resins include ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, polyethylene, polypropylene, styrene / isobutylene / styrene block copolymer, styrene / butadiene block copolymer, styrene / ethylene / butene copolymer. (Condensed polycyclic aromatic). Examples of rubber include styrene / butadiene rubber, chloroprene rubber, and natural rubber. Examples of the organic solvent include acetone, xylene, toluene and the like. Asphaltenes are high molecular compounds formed by cross-linking aromatic hydrocarbons of condensed rings. In addition, some of the items representing the quality of regenerative additives have standard values shown in the “Pavement Design and Construction Guidelines (Revised 2006; Japan Road Association)”, but asphalt mixture and pavement At present, there are many things that have not been sufficiently confirmed to be related to performance.

  “Asphalt pavement” refers to pavement laid with an asphalt mixture. The asphalt mixture includes aggregates such as gravel, fillers such as lime powder, and various asphalt compositions. Asphalt compositions include various asphalt modified asphalts in addition to straight asphalt and blown asphalt. The general asphalt pavement structure consists of four layers: surface layer, base layer, upper layer roadbed, and lower layer roadbed, and the asphalt pavement and its substructure roadbed are integrated to support and disperse traffic loads from above. It is like that.

  “Roadbed” refers to an asphalt pavement lower structure that disperses the traffic load transmitted from the upper layer of the asphalt pavement to the subgrade roadbed. The roadbed is covered with crushed stones and slag of uniform particle size, or crushed stones with bitumen, slaked lime, quicklime, cement, etc. added.

  “CBR” is an index representing the bearing capacity of the roadbed and roadbed.

  The “design CBR” is an index representing the bearing capacity of the road bed used when determining the thickness of the asphalt pavement. It was decided to represent them from several measured values of CBR obtained for the road extension direction and the depth direction of the roadbed in a section where the roadbed soil was almost constant.

  “Equivalent equivalent thickness (TA)” means the thickness necessary to withstand the load from above when it is assumed that all layers from asphalt pavement to the surface layer are made of asphalt mixture.

  “TA method” is one of the structural design methods for asphalt pavement. The equivalent thickness (TA) is calculated from the design CBR of the roadbed and the design traffic volume, and each layer of the pavement is not less than this. A method for determining the thickness.

  The “quality grade of recycled asphalt material” refers to a grade related to the degree of deterioration of the recycled asphalt material, which is determined using a gas released from the recycled asphalt material. Here, for the rating of recycled asphalt material, the gas released from the recycled asphalt material is used, and specifically, the amount of gas released from the recycled asphalt material obtained by using a measuring instrument or the mass reduction associated therewith. Optionally, the composition of the released gas is used as a criterion. The quality grade of recycled asphalt material is classified into, for example, three grades of high grade, intermediate grade, and low grade.

  “Advanced” means a quality grade in which the degree of deterioration of recycled asphalt material is small. For example, it is presumed that recycled asphalt materials having a gas emission amount of less than 0.1% are high grade.

  “Intermediate” refers to a quality grade in which the degree of deterioration of recycled asphalt material is moderate. For example, a recycled asphalt material having a gas release amount of 0.1% to 0.5% is estimated to be intermediate.

  “Lower grade” means a quality grade in which the degree of deterioration of recycled asphalt material is large. For example, a regenerated asphalt material with a gas emission amount exceeding 0.5% is estimated as a lower grade.

  “Background stability is good” means that the pressure fluctuation just before the measurement is as small as several percent in the gas measuring device, and the reproducibility of the gas measurement is good.

  According to the present invention, the quality of recycled asphalt material can be quickly and easily inspected before being used for paving.

  According to the present invention, for example, it is possible to distribute the evaluated recycled asphalt material to roads of a grade suitable for the quality grade, etc., and there is a mismatch between the grade of the construction target road and the grade of recycled asphalt material. No longer occurs. For example, high-grade recycled asphalt material is applied to roads with traffic volume of N6 or higher, intermediate-grade recycled asphalt material is applied to roads with traffic volume of N4 or N5, and small size of traffic volume of N3 or lower. Lower grade recycled asphalt materials will be applied to roads, parking lots and bicycle parking lots. As described above, by evaluating the quality grade of the recycled asphalt material using the inspection method of the present invention, it becomes possible to construct a pavement at an appropriate place without deviating greatly from the design specification.

Schematic process drawing for explaining recycling of asphalt material. (A)-(d) is process drawing which shows typically the procedure of the test | inspection of a recycled asphalt material, and pavement construction. The process figure which shows the outline | summary of the inspection method of the regenerated asphalt material for pavements which concerns on embodiment. Time chart showing time-series from factory shipment of recycled asphalt material to completion of paving work. The graph which shows the result of having investigated the time-dependent change of mass about various recycled asphalt materials and new asphalt materials. The graph of FIG. 5 which expanded and showed the vertical axis | shaft. The schematic block diagram which shows typically the gas component analysis system which analyzes the component contained in measurement gas qualitatively. The graph which shows the mass spectrum acquired about the gas each discharge | released from various reproduction | regeneration asphalt materials and a new asphalt material.

  Hereinafter, an inspection method for reclaimed asphalt material for pavement according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  First, with reference to FIG. 1 and FIG. 4, the flow of recycling of asphalt material for pavement will be schematically described.

  The deteriorated asphalt material peeled off from the asphalt paved road is loaded on a loading platform such as a large truck and transported from the construction site to a neighboring recycling factory (step S7 → step S1).

  When the deteriorated asphalt material is brought into the factory, the block block of the deteriorated asphalt material is first put into a pulverizer and pulverized until it breaks up. The crushed deteriorated asphalt material is put into a mixer equipped with a stirrer, and an appropriate amount of a regenerative additive is added thereto. The mixture of the deteriorated asphalt material and the regenerative additive is heated to a temperature equal to or higher than its softening point and softened, and the softened mixture is stirred with a stirrer and further mixed. Thereby, the pulverized deteriorated asphalt material and the regenerated additive are sufficiently mixed, and the deteriorated asphalt material is regenerated to obtain a regenerated asphalt material (step S2).

  Next, when it is time t0 that is calculated backward in consideration of transportation time (t0 to t1) so that it arrives at the time t1 about 30 minutes before the scheduled start time t2 of pavement construction (see Fig. 4) ) The truck is placed next to the factory shipping equipment, and the temperature-adjusted recycled asphalt material, for example, the repeatedly recycled asphalt material is mounted on the truck and shipped (step S3).

  In the factory, the temperature of the recycled asphalt material is controlled so that the temperature immediately before shipment falls within a range of 140 ° C. to 170 ° C., for example.

  The construction manager or truck driver covers the cargo bed with a heat insulating sheet so that the temperature of the recycled asphalt material does not drop during transportation and on-site standby. In this manner, the recycled asphalt material is strictly controlled so as not to fall below the lower limit temperature (eg, 140 ° C.) at which construction is possible (step S4). Especially in winter, the outside air temperature decreases, so the temperature control of recycled asphalt material is important. On the other hand, in the summer when the outside air temperature rises, the amount of released gas tends to increase, and a bad odor spreads in the vicinity. Therefore, measures such as covering the cargo bed with a seat are necessary.

  When the truck arrives at the construction site, an acceptance inspection is conducted for recycled asphalt material. In the acceptance inspection, various measurements are performed on the recycled asphalt material, and the quality of the recycled asphalt material is judged based on the result of the measurement. For example, while maintaining the temperature of the regenerated asphalt material at 140 ° C. or more, the total amount of gas released from the regenerated asphalt material or a part thereof within a certain period and the mass reduction of the regenerated asphalt material or a part thereof generated within a certain period And at least one of them is measured. And based on the result of this measurement, the quality of the recycled asphalt material is judged.

  The quality is judged by comparing the measurement result with a reference value. This reference value can be obtained, for example, by performing the same measurement as that performed on the recycled asphalt material on the new asphalt material.

Specifically, the acceptance inspection is performed as follows, for example.
First, a predetermined amount of recycled asphalt material is transferred from the truck bed onto the finisher. Next, as shown in FIG. 2 (a), the sensor portion 8a of the thermometer 8 and the collection tube 21a of the gas measuring device 21 are inserted into the regenerated asphalt material 5 on the finisher 2, and the internal temperature of the regenerated asphalt material 5 is measured. At the same time, the released gas is analyzed (step S5).

  Furthermore, an appropriate amount of sample is collected from the recycled asphalt material on the truck bed or the finisher 2, the collected sample is stored in a stainless steel container, and this container is suspended on the weighing hook of the load measuring test device and regenerated. The mass of the asphalt material sample is measured (step S5). A heater is disposed on the outer periphery of the sample storage container, and the mass of the sample can be measured while heating the sample together with the storage container to a desired workable temperature or higher, for example, 140 ° C. or higher. The storage container is made of a breathable material such as a stainless steel mesh, and the gas released from the sample is diffused to the outside of the container. For this reason, the sample mass which decreases every moment by volatilization of the component contained in a sample is measured continuously, for example.

  Record and save all of these measurements. In the present embodiment, the temperature measurement and gas analysis are performed on the recycled asphalt material on the finisher 2, but these may be performed on the recycled asphalt material on the truck bed.

  In the incoming inspection, the quality of recycled asphalt material is judged. For example, the quality grade is determined from three grades of high grade, intermediate grade, and low grade. When the quality grade of the recycled asphalt material is lower than the quality grade required for the construction target road as a result of the acceptance inspection, it is determined that a mismatch has occurred, and the recycled asphalt material is returned to the recycling factory (step S5 → Step S1). The recycled asphalt material returned to the factory is sent to pavement work such as a lower grade road or the like, or is reprocessed again.

  On the other hand, when the quality grade of the recycled asphalt material is equal to or higher than the quality grade required for the construction target road as a result of the acceptance inspection, the paving work is started using the recycled asphalt material that has arrived at the site (step S5 → step S6). ). As a guideline, the time t1 to t2 from the arrival of recycled asphalt material to the start of construction is approximately 30 minutes. For this reason, it is necessary to perform the incoming inspection quickly without taking a long time.

  When a series of pavement work is completed and the completion of the work is completed from the contractor to the orderer, the paved road is put into general use. Pavement materials that make up asphalt paved roads deteriorate over time due to repeated traffic loads due to traffic volume and vehicle weight. The pavement material deteriorated with age deteriorates the bonding force for bonding the aggregates and cannot withstand the traffic load, and causes damage such as cracks, depressions and steps on the road surface. If the degree of road surface damage becomes significant, it will not be possible to cover only by repairing the damaged part, and the entire road section will need to be paved again. That is, the pavement material that has deteriorated over time is peeled and removed (step S7), and the deteriorated asphalt material peeled off from the asphalt pavement is reclaimed as described above at the recycling plant and reused for pavement work ( Step S7 → Steps S1 to S6).

Next, an inspection method for recycled asphalt material will be described with reference to FIGS.
The recycled asphalt material is carried into the construction site, for example, at time t1 about 30 minutes before the scheduled pavement start time t2. The arrived recycled asphalt material is managed so as to maintain a temperature of 140 ° C. or higher, preferably 160 ° C. or higher even during conveyance after shipment from the factory.

  The recycled asphalt material is transferred from the truck bed to the finisher 2, and the temperature of the recycled asphalt material is measured on the finisher 2 (step S51). For the measurement of temperature, MODEL SK-1250MCIIIα manufactured by Sato Meter Co., Ltd. was used.

  In addition, a part of the recycled asphalt material is sampled, and the total amount of gas released by the sampled sample within a certain period or the mass loss of the sample that occurs within the certain period is measured by a load measuring test apparatus, and the composition of the emitted gas is further determined. Analyze (step S52).

  As a result, it is confirmed that the recycled asphalt material transferred to the finisher 2 is at a temperature of 140 ° C. or higher at which construction is possible, and the recycled asphalt material is based on the amount of gas released from the recycled asphalt material or the mass of the recycled asphalt material. The mass change rate is calculated. Further, the composition of the gas released from the recycled asphalt material can be obtained using the gas component analysis system.

  For this quantitative analysis, the method and apparatus described in Japanese Patent No. 397497 were used. Moreover, the method and apparatus described in the patent 4052597 gazette were used for the qualitative analysis of gas.

  Next, as shown in FIG. 2B, the regenerated asphalt material 5 is supplied from the finisher 2 onto the roadbed 3. As shown in FIG. 2C, the recycled asphalt material 5 is placed on the roadbed 3 so as to have a desired average height h2.

Next, as shown in FIG. 2 (d), a predetermined pressure is applied to the stacked recycled asphalt material 5 from above to compress the recycled asphalt material 5 and flatten the upper surface. For applying this pressure, a rolling roller 6 may be used, or a plate compactor or rammer 7 may be used. These devices have the ability to apply a pressure of at least 500 kg / m ² and flatten the road surface.

  The asphalt material 5 subjected to the compression flattening has an average height of h1 (<h2). The asphalt material 5 is compacted so that the specific gravity finally becomes 2.35 ± 0.1, for example.

  In addition, when a pressure is applied to the regenerated asphalt material 5, the liquid 5a may ooze out on the upper surface of the asphalt material. The amount of liquid 5a that oozes out tends to increase as the pressure increases. The liquid 5a that has oozed out is a part of the components of the regenerative additive (such as organic solvents and fats and oils), and the amount thereof has a strong correlation with the amount of released gas described later. In general, since the vapor pressure at the same temperature is higher in the liquid than in the solid, the amount of the released gas increases as the amount of the regeneration additive increases.

  From these facts, it is inferred that as the pavement planned traffic volume shown in Table 1 increases, the rate at which volatile components such as oil and organic solvents are separated and volatilized from the recycled asphalt material increases.

  Next, an evaluation test method and an evaluation test result of the recycled asphalt material will be described respectively.

1. Evaluation test method [Sample material]
The test materials are recycled asphalt material and new asphalt material.

  The recycled asphalt material is obtained by pulverizing a deteriorated asphalt material, a new asphalt material and a new aggregate, and mixing them with a regenerative additive to make them soft.

  On the other hand, the new asphalt material is a mixture of new aggregate and new asphalt.

  Six sample samples E11, E12, E13, E2, E3, and E4 and one reference sample sample R were prepared as test materials, respectively, and used for evaluation tests.

  Example Samples E11, E12, E13, E2, E3, and E4 are all recycled asphalt materials, and deteriorated asphalt before regeneration satisfies a penetration of 30 or more, and is manufactured at the same factory as road pavement material. , Are generally in circulation. These regenerated asphalt materials contain a regenerative additive in a range of 2 to 5% by mass.

  Sample R of the reference example is made of 100% new asphalt material. The new asphalt material is a mixture containing natural products such as asphaltene, naphthene, paraffin, resin, straight asphalt, blown asphalt.

2. Evaluation test results [temperature measurement results]
As a result of measuring the temperature on the finisher before construction, the average temperatures of samples E11, E12, E13, E2, E3, and E4 (average internal temperature of three-point measurement) are 164 ° C, 163 ° C, 165 ° C, They were 164 ° C, 166 ° C, and 165 ° C.

[Measurement results and evaluation of emitted gas]
Immediately after the truck loaded with recycled asphalt material arrives at the construction site, the gas released by the asphalt material loaded on the truck is collected.

  As shown in FIG. 2 (a), the gas collection tube 21a of the gas measuring device is inserted into the asphalt material, and the released gas is collected through a gas collection tube 21a into a container of a predetermined capacity (not shown). A thin stainless steel pipe can be used for the gas collecting pipe 21a.

  5 and 6, the horizontal axis indicates the elapsed time (minutes) from when the sample is suspended on the weighing hook of the load measuring test apparatus, and the vertical axis indicates the mass change rate (%) of various samples. 3 is a graph showing changes in mass of various samples over time. FIG. 6 is an enlarged view of the vertical axis of FIG. 5 for easy viewing.

  Six types of recycled asphalt samples E11, E12, E13, E2, E3, and E4 were put in dedicated containers, respectively, and the respective mass change rates were measured while being maintained at 150 to 170 ° C. The internal space of the container for storing the sample of the load measurement test apparatus was heated and held at 160 ± 10 ° C. with a heater before the measurement was started.

The mass change rate is given by ΔW (X) _t / W (X) ₀ . Here, W (X) ₀ is the initial mass of the sample X, W (X) _t is the mass at the time when the time t of the sample X has elapsed, and ΔW (X) _t (= W (X) _t −W (X ) ₀ ) shows the mass change with respect to the initial mass at the time when the time t of the sample X has elapsed.

  The relationship between the evaluation test results and the degree of degradation (quality grade) of recycled asphalt material is important. The quality grades of recycled asphalt materials are roughly classified into, for example, three grades: high grade, intermediate grade, and low grade.

  Here, as an example, if the mass change rate is less than 0.1%, the quality grade of the recycled asphalt material is estimated as high grade, and if the mass change rate is 0.1% or more and less than 0.4%, The quality grade of the asphalt material is estimated as intermediate, and if the mass change rate is 0.4% or more, the quality grade of the recycled asphalt material is estimated as lower.

  Curves E11, E12, E13, E2, E3, and E4 in the figure show the results of the example samples E11, E12, E13, E2, E3, and E4, respectively. A curve R in the figure shows the result of the reference example sample R.

  As is clear from both figures, the mass change rate is small in the example samples E11, E12, and E13, whereas the mass change rate is significantly large in the example samples E2, E3, and E4. Specifically, the mass loss that occurred within 30 minutes from the start of measurement was 0.02% and 0.05% for Example Samples E11 and E12, and 0.14% for Example Sample E13, respectively. E2, E3, and E4 were 0.65%, 0.87%, and 2.60%, respectively. In the reference example sample R, the mass loss that occurred within 30 minutes from the start of measurement was less than 0.02%.

  From these results, the quality grades of the sample samples E11 and E12 are estimated to be high grade, the quality grade of the sample sample E13 is estimated to be intermediate, and the quality grade of the sample samples E2, E3, and E4 is estimated to be low grade. . Of these, the sample E4 in particular produced a mass loss of 2.60% during the 30 minutes from the start of measurement, and can be said to be an extremely poor material among the lower grades.

  The collected gas components were analyzed using the mass spectrum analysis system 20 shown in FIG. The mass spectrum analysis system 20 includes a gas measurement device 21, a data processing unit 22, and a display unit 23, and is an external database 24 that can access library data of the National Institute of Standards and Technology (NIST) via an Internet line. It is. The NIST library stores data for approximately 240,000 kinds of chemical substances so that they can be read out at any time.

  The gas measuring device 21 of the mass spectrum analysis system includes a sample introduction unit communicating with the gas collection tube 21a, an ion source for ionizing the collection gas introduced through the sample introduction unit, and a gas sample ionized by the ion source. An analysis unit for separating and analyzing, and a detection unit for sensitizing and detecting ions selected by the analysis unit are provided.

  As the gas measuring device 21, the device described in Japanese Patent No. 4052597 was used. The measurement time per sample of the gas measuring device is about 10 seconds, and the measurement result can be obtained quickly.

Measurement data obtained by the gas measuring device 21 is sent to the data processing unit 22 together with background data (BG data), and data processing is performed by the data processing unit 22 to create a mass spectrum. The data processing unit 22 collates the obtained mass spectrum with about 240,000 kinds of chemical substances in the NIST library data. That is, when the measurement data and the background data (BG data) are input from the gas measurement device 21, the data processing unit 22 verifies the stability of the BG data and corrects the measurement data, so that the mass of the subject gas While creating a spectrum graph, the library data of NIST is called, and the created mass spectrum graph of the analyte gas is collated (pattern matching) with the mass spectrum graphs of approximately 240,000 kinds of chemical substances, and included in the analyte gas. It identifies the chemical substance. Here, the verification of the stability of the BG data is to confirm that the pressure fluctuation just before the measurement is as small as several percent or less and the repeatability is very good. The background pressure is in an ultrahigh vacuum region of 10 ⁻⁵ Pa or less.

  The data processing unit 22 not only identifies the chemical substance contained in the analyte gas, but also displays a mass spectrum graph of the created analyte gas on the screen of the display unit 23 and various measurement data (temperatures). Measurement results, gas emission measurement results, mass change rate calculation results, emission gas component analysis results, etc.) are recorded and stored so that they can be read out at any time.

  In the present embodiment, for example, the mass of the recycled asphalt material immediately after arrival at the site and the mass of the recycled asphalt material after a certain time, for example, 30 minutes from the arrival at the site, are measured, respectively, and the quality grade of the recycled asphalt material from the mass change rate. Is estimated. Over time, the component gas of the regenerated additive is released from the regenerated asphalt material, and the mass of the regenerated asphalt material decreases. Here, when the regenerated asphalt material releases the component gas of the regenerated additive, the binder function for bonding the aggregates decreases, so it is estimated that the regenerated asphalt material with a small amount of gas release is excellent in quality. Further, it is presumed that the amount and composition of the regenerative additive added to the regenerated asphalt material are strongly related to the amount and composition of the gas released from the pavement sample. In particular, it is surmised that the amount of gas released is strongly related to the amount of regeneration additive added.

  Therefore, by comparing the total amount P of gas released from the regenerated asphalt material within a certain period of time from the start of measurement, for example, 30 minutes, with the total amount Q of gas released from the new asphalt material within the same period. The quality grade of recycled asphalt material can be estimated. For example, if the amounts P and Q are the total amount of gas released within 30 minutes from the start of measurement, when the amount P is less than 5 times the amount Q, the quality grade of recycled asphalt material is advanced. When the amount P is 5 times or more and less than 10 times the amount Q, the quality grade of the recycled asphalt material is estimated as intermediate, and when the amount P is 10 times or more the amount Q, the quality of the recycled asphalt material The grade can be estimated as a lower grade. Typically, the quantity P is measured at the construction site, and the quantity Q is measured at the construction site prior to the measurement of the quantity P, or at a place other than the construction site such as a recycling factory.

  When the mass spectrum analysis method is used, components contained in the gas can be identified. Therefore, if a mass spectrum analysis is performed on the gas released from recycled asphalt material transported to the construction site, for example, the specified chemical substances specified in the Ordinance for Enforcement of the Industrial Safety and Health Act shall not be included in the released gas. Can be confirmed on the spot. Therefore, by examining the composition of the gas released from the recycled asphalt material together with the mass change rate of the recycled asphalt material, the rating accuracy of the quality grade of the recycled asphalt material is improved.

  FIG. 8 is a graph showing an example of data obtained by mass spectrum analysis. In FIG. 8, the horizontal axis represents the mass-to-charge ratio m / z, and the vertical axis represents the ionization current ratio (relative value). In FIG. 8, for each of the three example samples E12, E2, E4 and the reference example sample R, a curve formed by connecting the peak points of the obtained spectrum graph is drawn.

  The ionization current ratio shown in FIG. 8 is a relative value based on the ionization current obtained when the mass-to-charge ratio m / z is 40, which is obtained from the mass spectrum of argon. In the atmosphere, argon is stably present in an amount of 9300 ppm. Since argon (molecular weight 40) is small in nature, the ionization current of argon is used as a reference.

  According to this embodiment, since the quality grade of the repeatedly recycled asphalt material can be estimated at the site as described above, the recycled asphalt material suitable for the grade of the construction target road, for example, the repeatedly recycled asphalt material can be used for the construction. .

  In addition, this invention is not limited only to the said embodiment, In the implementation stage, each component can be deform | transformed and embodied in the range which does not deviate from the summary. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment.

  2 ... Finisher, 3 ... Roadbed, 5 ... Recycled asphalt material, 5a ... Exuded component liquid (part of regenerated additive), 6 ... Rolling roller or tire roller, 7 ... Plate compactor or rammer, 8 ... Temperature 8a ... sensor unit, 9 ... gas analyzer, 9a ... gas detection probe, 20 ... mass spectrum analysis system, 21 ... gas measuring device, 21a ... gas collection tube, 22 ... data processing unit, 23 ... display unit, 24 ... database.

Claims (6)

A method for inspecting the quality of a regenerated asphalt material obtained by adding a regenerated additive to a used asphalt material and adjusting the temperature to 140 ° C. or more before using the regenerated asphalt material for pavement,
While maintaining the temperature of the regenerated asphalt material at 140 ° C. or higher, the total amount of gas released from the regenerated asphalt material or a part thereof within a predetermined period and the mass of the regenerated asphalt material or a part thereof generated within the predetermined period Measuring at least one of a decrease;
An inspection method including judging the quality of the recycled asphalt material based on the result of the measurement.   The inspection method according to claim 1, wherein the quality of the recycled asphalt material is determined by comparing the mass reduction or a ratio of the mass reduction with respect to an initial mass of the recycled asphalt material or a part thereof with a reference value.   The predetermined period is 30 minutes, and if the ratio of the mass reduction to the initial mass of the recycled asphalt material or a part thereof is less than 0.1%, the quality of the recycled asphalt material is judged to be high grade, If the ratio is 0.1% or more and less than 0.4%, the quality of the recycled asphalt material is judged as intermediate, and if the ratio is 0.4% or more, the quality of the recycled asphalt material is inferior. The inspection method according to claim 1, wherein the inspection method is determined.   The inspection method according to claim 1, wherein the quality of the recycled asphalt material is determined by comparing the total amount of the gas with a reference value.   The total amount of gas released from the regenerated asphalt material or part thereof within 30 minutes is P, and the total amount of gas released from the new asphalt material under the same conditions as the measurement for the regenerated asphalt material or part thereof is Q. When the total amount P is less than 5 times the total amount Q, it is judged that the quality of the recycled asphalt material is high grade, and when the total amount P is 5 times or more and less than 10 times the total amount Q. The inspection method according to claim 4, wherein the quality of the recycled asphalt material is determined to be intermediate, and the quality of the recycled asphalt material is determined to be inferior if the total amount P is 10 times or more the total amount Q. Measuring a mass spectrum for the gas released from the regenerated asphalt material or a part thereof, and identifying a component contained in the gas from the mass spectrum;
The inspection method according to claim 1, further comprising confirming whether the identified component contains a specific chemical substance.