JP5566653B2 - Manufacturing method and construction method of asphalt mixture - Google Patents

Description

  The present invention relates to a manufacturing method and a construction method of an asphalt mixture used for a paved road.

  Pavement using an asphalt mixture is prepared by mixing, for example, straight asphalt in a heated state with aggregates such as crushed stone and sand having an appropriate particle size distribution as a binder, and heating the asphalt mixture. It is constructed by spreading on the surface and rolling with a roller.

  In recent years, due to an increase in traffic volume and an increase in large vehicles such as trucks, a phenomenon has frequently occurred on asphalt paved roads in which the asphalt mixture laid gradually flows due to the passage of vehicles and causes rutting. If the road surface is uneven, it will not only make the ride comfortable, but it will also affect the steering operation. Become.

  In order to prevent the flow of the asphalt mixture, which is the cause of such irregularities, it has been proposed to use a modified asphalt obtained by adding a modifying material such as rubber or thermoplastic elastomer to straight asphalt. Patent Document 1 describes that a wax-like substance obtained by a thermal decomposition reaction of a synthetic resin such as a polyethylene resin is added to asphalt as an asphalt modifier to produce an asphalt mixture. In Patent Document 2, a special additive composed of petroleum or synthetic wax having a melting point of 50 to 90 ° C. is added to a mixture mainly composed of aggregate and asphalt in an amount of 1% to 7% by weight based on the amount of asphalt. The point of adding and producing an asphalt mixture is described.

Japanese Patent No. 3311299 Japanese Patent No. 3628274

  In patent document 1 and 2 mentioned above, while adding the wax-like substance to asphalt, while improving the durability of asphalt, the heating temperature of asphalt at the time of construction can be lowered, and work efficiency can be improved. it can.

  However, when a wax-like substance is added to asphalt, it becomes a modified asphalt having characteristics different from those of straight asphalt, and therefore it is necessary to set the amount to be different from the amount of asphalt in the case of an asphalt mixture using straight asphalt.

  When straight asphalt is used, the blending ratio of asphalt and aggregate is determined based on the Marshall stability test, but when using the modified asphalt described above, the determined blending ratio is used as it is. Even if it is applied, a product with sufficient durability cannot be obtained when constructed.

  In particular, when paraffin is added to asphalt as a modifier, paraffin tends to reduce the gap between aggregates because of its large shrinkage rate when solidified. Therefore, when setting the design asphalt amount (asphalt blending ratio) based on the test results based on the Marshall stability test, the design asphalt amount is set smaller than the straight asphalt amount due to the decrease in aggregate porosity, and the asphalt amount Tends to be insufficient, and the durability when the manufactured asphalt mixture is applied tends to be insufficient.

  Accordingly, the present invention provides a manufacturing method for setting and manufacturing an asphalt mixture ratio so as to have sufficient durability when an asphalt mixture to which paraffinic hydrocarbons are added as a modifier is applied, and the application of the asphalt mixture. It is intended to provide a method.

The method for producing an asphalt mixture according to the present invention comprises 2% to a modifier mainly composed of paraffinic hydrocarbons obtained by burning and thermally decomposing a high-molecular synthetic resin material having self-combustibility. In a method for producing an asphalt mixture in which 8% is added and asphalt and aggregate are mixed, the blending ratio A _p (weight%) of the asphalt containing a modifier is set to a value calculated by the following formula and mixed. It is characterized by that.
A _p = A _s · (V _p / V _s ) ^1/3 · (γ _p / γ _s )
However,
A _s; straight asphalt and the mixing ratio of the asphalt which is set by the test results based on Marshall stability test were performed on the asphalt mixture obtained by mixing aggregate (wt%)
V _s ; Aggregate porosity (%) of the specimen prepared when the Marshall stability test is performed on the asphalt mixture in which straight asphalt and aggregate are mixed
γ _s : Specific gravity of straight asphalt V _p ; Aggregate porosity (%) of the specimen prepared when the Marshall stability test is performed on the asphalt mixture in which the asphalt containing the modifier and the aggregate are mixed
γ _p ; Specific gravity of asphalt containing modifier

  Further, the modifier is added in a liquid state or in a granular form having a particle size of 3 mm or less and mixed with asphalt and aggregate.

  The construction method of the asphalt mixture according to the present invention is characterized in that in the construction method of constructing the asphalt mixture produced by the above production method, the number of times of rolling is performed 6 times at a secondary rolling temperature of 100 ° C to 120 ° C. To do.

  The present invention can be manufactured by setting the blending ratio of asphalt so as to have sufficient durability when the asphalt mixture to which paraffinic hydrocarbon is added as a modifier is provided by having the above-described configuration. it can.

  Hereinafter, embodiments according to the present invention will be described in detail. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

  In the production method according to the present invention, a modifier containing paraffinic hydrocarbon as a main component (hereinafter abbreviated as “paraffinic modifier”) is added to mix asphalt and aggregate to produce an asphalt mixture. . Paraffinic hydrocarbons have a low melting point and have a low viscosity at the temperature at which asphalt and aggregate are mixed (about 150 ° C.), and therefore can be mixed even in the conventional manufacturing process of asphalt mixture.

  As described in Patent Document 1 described above, paraffinic hydrocarbons are thermally decomposed by burning a high-molecular synthetic resin material having self-combustibility such as polyolefin resin such as polyethylene resin and polypropylene resin, and polystyrene resin. Can be generated. Since such a high-molecular synthetic resin material is widely used as a coating material for cables, paraffinic hydrocarbons can be produced at low cost by using waste cables. What was manufactured in this way should just be used as a paraffin type modifier.

  When using asphalt mixture as a pavement material for roads, etc., it is necessary that the installed asphalt mixture has sufficient durability for a long period of time. In order to check such durability, marshalling is performed on the asphalt mixture. A stability test method is implemented.

  As for the details of the Marshall stability test method, a specific implementation method is determined as described in “Japanese Pavement Survey and Test Method Handbook” (item B001) edited by the Japan Road Association. First, prepare a specific aggregate and asphalt, set the temperature at which the kinematic viscosity of the asphalt reaches a predetermined value to the mixing temperature and compaction temperature, mix the aggregate and asphalt and compact the specimen. Create The density of the prepared specimen is measured according to “Density test method for asphalt mixture” (pavement survey and test method manual; item B008).

  Next, a load is applied to the created specimen at a predetermined displacement speed, the load when the applied load starts to decrease is measured as the maximum load, and the amount of deformation from the start of load application to the maximum load is measured. To do. Then, the stability (unit: kN) is calculated from the measured maximum load. Further, the flow value (unit: 1/100 cm) is calculated from the average value of the deformation amount at the start of applying the load and the deformation amount at the time of applying the maximum load.

When setting the design asphalt amount of the asphalt mixture (asphalt blending ratio; weight%), the Japan Road Association “Pavement Handbook” (Item 6-3-3; Setting the Design Asphalt Amount, page 100- 104), in addition to the density, stability and flow value of the specimen obtained in the Marshall stability test, the porosity (%), saturation (%) and aggregate porosity (% ) Is calculated by the following equation.
Void ratio (%); V _v = (1−D _m / D _t ) × 100
Saturation (%); V _fa = V _a / (V _a + V _v ) × 100
Aggregate porosity (%); V _ma = V _v + W _a · D _m / D _a
Here, D _m is the density of the specimen (g / cm ³ ), D _a is the density of asphalt (g / cm ³ ), D _t is the theoretical maximum density (g / cm ³ ), and V _a is the volume percentage of asphalt. (%), W _a is the blending ratio (%) of asphalt, and D _t and V _a can be obtained from a predetermined calculation formula.

  Standard values are set in advance for the porosity and saturation calculated in this way, and the stability and flow values obtained by the Marshall stability test method, and a common range for the blending ratio of asphalt that satisfies all these reference values is designed. Set as the amount of asphalt.

  The design asphalt amount setting method described above is based on an asphalt mixture obtained by mixing straight asphalt with aggregate. For this reason, in the case of the asphalt mixture to which the above-described paraffinic hydrocarbon is added as a modifier, the characteristics are different from those when only straight asphalt is used, and thus the set blending ratio of asphalt cannot be used as it is.

  In the case of an asphalt mixture to which paraffinic hydrocarbons are added, since the shrinkage rate when the paraffinic hydrocarbons solidify is large, the gap between the aggregates tends to be small. For this reason, a design asphalt amount that satisfies the above-described reference value is set low, and if the set design asphalt amount is used as it is, the amount of asphalt to be mixed is reduced and the durability becomes insufficient.

  Therefore, when paraffinic hydrocarbons are added, it is necessary to increase the amount of asphalt to be mixed and improve the durability. However, if the amount of asphalt is too large, the asphalt will float on the surface when installed and the asphalt mixture Becomes non-uniform and the durability is rather lowered.

  Based on the above points, for the asphalt mixture to which paraffinic hydrocarbons are added, an appropriate designed asphalt amount must be set apart from the conventional designed asphalt amount. As described above, the aggregate gap contracts as compared with the case where only straight asphalt is mixed. Therefore, it is necessary to consider the reduction of the aggregate porosity when setting an appropriate design asphalt amount.

First, the film thickness μ (10 ⁻³ mm) of asphalt formed on the aggregate surface is calculated by the following equation.
μ = A / (S · γ)
Here, A is the designed asphalt amount (% by weight), S is the surface area (m ² / kg) per unit weight of the total aggregate, and γ is the specific gravity of the asphalt.

For the asphalt mixture when only straight asphalt is mixed, the film thickness μ _s and the aggregate porosity V _s are calculated by the following equations.
μ _s = A _s / (S · γ _s )
V _s = V _vs + W _as · D _ms / D _as
Here, A _s is the design asphalt amount when only straight asphalt is mixed, γ _s is the specific gravity of straight asphalt, D _ms is the density of the specimen of the asphalt mixture mixed only with straight asphalt, D _as is the density of straight asphalt, V _vs the porosity of the specimens of the asphalt mixture was mixed only straight asphalt, W _{the as} is the blending ratio of the straight asphalt. The aggregate porosity V _s is calculated in the same manner as the above-described aggregate porosity V _ma .

Moreover, about the asphalt mixture at the time of adding a paraffin type modifier, film thickness (mu) _p and aggregate porosity _Vp are calculated by the following formula | equation. The surface area S per unit weight of the total aggregate is the same as when only straight asphalt is mixed, and the design asphalt amount indicates the blending ratio with respect to the total amount of the paraffinic modifier and straight asphalt.
μ _p = A _p / (S · γ _p )
V _p = V _vp + W _ap · D _mp / D _ap
Here, A _p is the amount of design asphalt when paraffinic modifier is added, γ _p is the specific gravity of asphalt with paraffinic modifier added to straight asphalt, D _mp is asphalt with paraffinic modifier added density of the specimen of the mixture, D _ap is the density of the asphalt with the addition of paraffin-based modifier to straight asphalt, V _vp the porosity of the specimens of the asphalt mixture was added paraffinic modifier, W _{the as} straight asphalt It is a blending ratio of asphalt to which a paraffinic modifier is added. The aggregate porosity V _p is calculated in the same manner as the above-described aggregate porosity V _ma .

The aggregate porosity is a parameter related to the volume (volume) between the aggregates, and the asphalt film thickness is a parameter related to the interval (length) between the aggregates. Therefore, it can be assumed that the ratio of the film thickness is equal to the cube root of the ratio of the aggregate porosity due to the relationship between the length and the volume. That is, the following relational expression can be derived.
μ _p / μ _s = (V _p / V _s ) ^1/3
Based on this relational expression, a relational expression of the design asphalt amount can be derived as follows.
μ _p = μ _s · (V _p / V _s ) ^1/3
A _p / (S · γ _p ) = A _s / (S · γ _s ) · (V _p / V _s ) ^1/3
A _p = A _s · (V _p / V _s ) ^1/3 · (γ _p / γ _s ) (Equation 1)

Therefore, appropriate design asphalt amount A _p of adding paraffin modifier, the ratio of aggregate porosity in the design asphalt amount A _s of straight asphalt by Marshall stability test method or the like based on the (Equation 1) It can be obtained by multiplying the cube root and the ratio of specific gravity.

  The asphalt mixture was manufactured based on the design asphalt amount set according to (Equation 1), and an experiment was conducted on durability when it was constructed. As the asphalt mixture, a fine-grained asphalt mixture was produced using an aggregate having a maximum particle size of 20 mm. Asphalt, five types of asphalt were used with the amount of straight asphalt set to 100% and the addition rate of paraffinic modifier set to 0%, 2%, 4%, 6%, and 8%. In addition, the regenerated paraffin manufactured with the well-known manufacturing apparatus using the waste material of the cable was used for the paraffin type modifier.

A Marshall stability test was performed using five types of asphalt, and a design asphalt amount A (% by weight) and an aggregate porosity V (%) were obtained. Moreover, since the case where the addition rate of the paraffinic modifier is 0% corresponds to the case where only straight asphalt is mixed, the addition rate of 2% or more using the set asphalt amount and the aggregate porosity when the addition rate is 0% the design asphalt amount a _p in the case of 8% was calculated by (equation 1). In addition, about specific gravity, when the paraffinic modifier was added, the ratio of specific gravity was set to 1 so that it might be hardly different from the case where it was not added. The calculation results are shown in Table 1.

表１の算出結果をみると、設計アスファルト量Ａよりも（式１）による設計アスファルト量Ａ_pの方が配合割合が大きくなっていることがわかる。

Looking at the calculation result of Table 1, it can be seen that proportion who design asphalt amount A _p due than the design asphalt content A (Formula 1) is increased.

Was calculated dynamic stability (times / mm) according to the wheel tracking test method for asphalt mixture was mixed based on the design asphalt amount A and the design asphalt amount A _p. Table 2 shows the calculation results.

表２の算出結果をみると、添加率が２％及び４％では、従来の設計アスファルト量Ａで設定されたアスファルト混合物の動的安定度が設計アスファルト量Ａ_pの場合に比べて若干上回っているが、動的安定度５０００回／ｍｍを超える流動防止の実用範囲においては、設計アスファルト量Ａ_pに基づいて混合したアスファルト混合物の動的安定度が設計アスファルト量Ａの場合に比べて大きく上回っており、より適切な設計アスファルト量が設定されていることがわかる。

Looking at the calculation result of Table 2, the 2% addition rate and 4%, the dynamic stability of a conventional set in the design asphalt amount A asphalt mixture is slightly higher than compared to the case of the design asphalt amount A _p are, but in a practical range of movement preventing more than dynamic stability 5000 times / mm, greater than greater than when the dynamic stability of the asphalt mixture was mixed based on the design asphalt amount a _p of the design asphalt amount a It can be seen that a more appropriate design asphalt amount is set.

  From the above, by setting the design asphalt amount according to (Equation 1), it is possible to accurately and easily determine the appropriate design asphalt amount when the paraffinic modifier is added while using the conventional design asphalt amount setting method. It became possible to set to.

  When manufacturing an asphalt mixture based on the design asphalt amount set in this way, it is difficult to mix the paraffinic modifier into straight asphalt at the actual construction site in time, so aggregate is introduced. A manufacturing method in which a paraffinic modifier is introduced into a mixer together with straight asphalt and mixed is preferable.

  However, when the paraffinic modifier is added together with straight asphalt, a uniform quality asphalt mixture cannot be produced unless the paraffinic modifier is uniformly mixed with the straight asphalt within a short time.

  In order to mix the paraffinic modifier in a short time, it is desirable that the paraffinic modifier is liquefied or granulated to a particle size of 3 mm or less in advance. When the paraffinic modifier is liquefied and charged, a predetermined amount of the solid paraffinic modifier to be charged is weighed and then liquefied by adding it to a heating container, and the liquefied paraffinic modifier is mixed into the mixer. Can be added to straight asphalt. When the paraffinic modifier is granulated and charged, the solid paraffinic modifier is pulverized in advance by a crushing apparatus and sieved to prepare a paraffinic modifier having a particle size of 3 mm or less. Then, the amount of granular paraffinic modifier to be charged may be measured and then charged into the mixer together with straight asphalt.

  We manufactured an asphalt mixture to which a paraffinic modifier with a particle size of more than 3 mm, a granular paraffinic modifier with a particle size of 3 mm or less, and a liquid paraffinic modifier were added. It was. As the asphalt mixture, a fine-grained asphalt mixture was produced using an aggregate having a maximum particle size of 20 mm. Asphalt, the amount of straight asphalt was set to 100%, and the addition rate of paraffinic modifier was set to 4%, 6%, and 8%. In addition, the regenerated paraffin manufactured with the well-known manufacturing apparatus using the waste material of the cable was used for the paraffin type modifier.

  First, aggregate was put into a commercially available asphalt mixer (output 37 kw, 55 rpm), straight asphalt and granular or liquid paraffinic modifier were added together, and the mixture was stirred and mixed at a heating temperature of about 175 ° C. for about 1 minute. The dynamic stability (times / mm) was calculated for the mixed asphalt mixture according to the wheel tracking test method. Table 3 shows the calculation results.

表３の算出結果をみると、粒径３ｍｍ以下又は液状のパラフィン系改質剤を用いて製造したアスファルト混合物の動的安定度が粒径３ｍｍを超える場合に比べて大きく上回っており、耐久性を大幅に向上させたアスファルト混合物が得られることがわかる。

Looking at the calculation results in Table 3, the dynamic stability of the asphalt mixture produced with a particle size of 3 mm or less or using a liquid paraffinic modifier is much higher than when the particle size exceeds 3 mm, and the durability is high. It can be seen that an asphalt mixture with significantly improved slag is obtained.

  Next, it experimented about the case where it constructs on a paved road etc. using the asphalt mixture which added the paraffin type modifier.

  First, an asphalt mixture to which a liquid paraffinic modifier was added was produced, and when the produced asphalt mixture was applied, an experiment was conducted on the relationship between the rolling pressure temperature and the dynamic stability. In this experiment, an asphalt mixture is applied based on the wheel tracking test method, the rolling temperature in the preliminary rolling is set as the primary rolling temperature, and the rolling pressure in the roller rolling is set as the secondary rolling temperature.

  As the asphalt mixture, a fine-grained asphalt mixture was produced using an aggregate having a maximum particle size of 20 mm. Asphalt, the amount of straight asphalt was set to 100%, and the addition rate of the liquid paraffinic modifier was set to 8%. In addition, the regenerated paraffin manufactured with the well-known manufacturing apparatus using the waste material of the cable was used for the paraffin type modifier.

  Aggregate was put into a commercially available asphalt mixer (output 37 kw, 55 rpm), straight asphalt and liquid paraffinic modifier were added together, and the mixture was stirred and mixed at a heating temperature of about 175 ° C. for about 1 minute. The mixed asphalt mixture was constructed based on the wheel tracking test method. At that time, the dynamic rolling stability (times / mm) was calculated by setting the roller rolling pressure to 6 times and setting the secondary rolling temperature in the roller rolling to 80 ° C., 100 ° C., and 120 ° C.

  The calculated dynamic stability was 5,727 times / mm at 80 ° C., 7,000 times / mm at 100 ° C., and 7,000 times / mm at 120 ° C. Therefore, it can be seen that if the secondary rolling temperature is 100 ° C. or higher, sufficient dynamic stability can be obtained. Moreover, since asphalt will adhere to a tire roller when it exceeds 120 degreeC, if workability is considered, what is necessary is just to set secondary rolling pressure temperature to 100 to 120 degreeC.

  Next, in the case of manufacturing an asphalt mixture to which a granular paraffinic modifier having a particle size of 3 mm or less is added and applying the manufactured asphalt mixture, the number of roller rolling pressures and the dynamic stability Experiments were conducted on the relationship. As the asphalt mixture, a fine-grained asphalt mixture was produced using an aggregate having a maximum particle size of 20 mm. Asphalt, the amount of straight asphalt was set to 100%, and the addition rate of the liquid paraffinic modifier was set to 5%. In addition, the regenerated paraffin manufactured with the well-known manufacturing apparatus using the waste material of the cable was used for the paraffin type modifier.

  Aggregate was added to a commercially available asphalt mixer (output 37 kw, 55 rpm), straight asphalt and granular paraffinic modifier were added together, and the mixture was stirred and mixed at a heating temperature of about 175 ° C. for about 1 minute. About the mixed asphalt mixture, using a 15t tire roller and a 25t tire roller as a rolling machine, and based on a wheel tracking test method, at a secondary rolling temperature of 110 ° C., the number of rolling times of roller rolling is 3 The dynamic stability (times / mm) was calculated by setting times, 6 times, and 9 times.

  The calculated dynamic stability was 2,250 times / mm for 3 times, 2,333 times / mm for 6 times, and 2,100 times / mm for 9 times in the case of a 15t tire roller. In the case of a 25t tire roller, it was 1,969 times / mm for 3 times, 3,000 times / mm for 6 times, and 2,423 times / mm for 9 times. Therefore, it can be seen that the dynamic stability is highest when the number of rolling times is six.

  As described above, when manufacturing an asphalt mixture to which a paraffinic modifier is added, sufficient durability can be provided when construction is performed by setting the design asphalt amount based on (Equation 1). it can. In addition, when manufacturing an asphalt mixture, a paraffinic modifier having a liquid or particle size of 3 mm or less is added, and the asphalt mixture in which the paraffinic modifier is uniformly mixed in a construction site in a short time. Can be manufactured. Furthermore, when constructing the manufactured asphalt mixture, sufficient durability can be reliably obtained by performing the number of times of rolling six times at a secondary rolling temperature of 100 ° C. to 120 ° C. in the rolling step.

Claims (3)

Add 2% to 8% of a modifier based on paraffinic hydrocarbons obtained by burning and pyrolyzing high-molecular synthetic resin materials with self-combustibility to mix asphalt and aggregate In the manufacturing method of an asphalt mixture, the mixing ratio A _p (wt%) of the asphalt containing a modifier is set to a value calculated by the following formula and mixed.
A _p = A _s · (V _p / V _s ) ^1/3 · (γ _p / γ _s )
However,
A _s; straight asphalt and the mixing ratio of the asphalt which is set by the test results based on Marshall stability test were performed on the asphalt mixture obtained by mixing aggregate (wt%)
V _s ; Aggregate porosity (%) of the specimen prepared when the Marshall stability test is performed on the asphalt mixture in which straight asphalt and aggregate are mixed
γ _s : Specific gravity of straight asphalt V _p ; Aggregate porosity (%) of the specimen prepared when the Marshall stability test is performed on the asphalt mixture in which the asphalt containing the modifier and the aggregate are mixed
γ _p ; Specific gravity of asphalt containing modifier The manufacturing method according to claim 1, wherein the modifier is added in a liquid state or in a granular form having a particle size of 3 mm or less and mixed with asphalt and aggregate. In the construction method which constructs the asphalt mixture manufactured by the manufacturing method of Claim 1 or 2, the number of rolling is performed 6 times at the secondary rolling temperature of 100 ° C to 120 ° C. Method.