CN110220818A - A kind of experimental rig and test method measuring heat regeneration asphalt mixture theoretical maximum specific density - Google Patents

Abstract

The invention belongs to the technical field of highway asphalt pavement regeneration, and particularly relates to a test device and a test method for measuring the theoretical maximum relative density of thermally recycled asphalt mixture. The test device consists of a stirring module, a weighing module, a water injection module, an asphalt injection module, a heating module and a control module. The test method uses the above-mentioned test device to use asphalt as the medium, and through heating, stirring and standing, the asphalt is fully immersed in the mixture to fill the voids, and then the maximum theoretical relative density is obtained by measuring the mass and volume of the hot recycled asphalt mixture. The test process The operations such as stirring, weighing, water injection, asphalt injection, heating and calculation are automatically completed by the control module, and the test results are stable, accurate and reliable, which can effectively improve the road performance of the thermally recycled asphalt mixture and promote the thermal performance of the asphalt pavement. Promotion and application of regeneration technology.

Description

A test device for determining the theoretical maximum relative density of thermally recycled asphalt mixture and experiment method

technical field

The invention belongs to the technical field of highway asphalt pavement regeneration, and particularly relates to a test device and a test method for measuring the theoretical maximum relative density of thermally recycled asphalt mixture.

Background technique

Asphalt pavement recycling technology, especially factory mix or in-situ hot recycling technology, is more and more used. The theoretical maximum relative density of hot recycled asphalt mixture refers to the mass of the sample per unit volume when the mixture is compacted to an ideal state without voids. The density ratio of water at the same temperature. The theoretical maximum relative density is the basis for calculating volume indexes such as porosity, and it is also an important parameter for the calculation of road compaction. A very critical technical index in the design, construction and quality evaluation of thermally recycled asphalt mixture.

According to the "Technical Specifications for Construction of Highway Asphalt Pavement" (JTG F40-2004), the current measurement methods for the theoretical maximum relative density of asphalt mixtures include calculation methods and actual measurement methods, and the actual measurement methods include vacuum method and solvent method. Highway Engineering Asphalt and Asphalt Mixture Test Regulations (JTG E20-2011), based on a large number of tests, the applicant analyzed the following problems in the determination of the maximum theoretical density of thermally recycled asphalt mixture by the above method: (1) If the recycled asphalt If the modified asphalt is contained in the pavement material, or the modified asphalt is used to mix the hot recycled asphalt mixture, the modified asphalt has a high viscosity, and the voids in the mixture are difficult to be completely filled with water when measured by the vacuum method, which makes the test results difficult. Inaccurate; (2) Using the solvent method requires a lot of trichloroethylene solvent, and trichloroethylene has an impact on the environment and human body, and the waste liquid produced by this method is usually difficult to handle; (3) The calculation method can be determined by measuring each The density of mineral materials, asphalt and other additives, and the maximum theoretical density is calculated according to the ratio, but the density of the old aggregate and mineral powder obtained after extraction or combustion recovery is difficult to accurately measure, and the recovery of fiber materials and Measurement is even more impossible. Therefore, there is still a lack of a rapid and accurate method for determining the theoretical maximum relative density of thermally recycled asphalt mixtures.

SUMMARY OF THE INVENTION

In view of the problems existing in the above test methods, the purpose of the present invention is to provide a test device and test method for measuring the theoretical maximum relative density of thermally regenerated asphalt mixture. , which can make the asphalt fully fill the open voids of the hot recycled asphalt mixture, and at the same time accurately measure the mass and solid volume of the mixture (without open voids), and then calculate the theoretical maximum relative density of the hot recycled asphalt mixture.

To achieve the above object, the present invention adopts the following technical solutions:

A test device for measuring the theoretical maximum relative density of thermally regenerated asphalt mixture consists of a stirring module 1, a weighing module 2, a water injection module 3, an asphalt injection module 4, a heating module 5 and a control module 6.

There are two stirring modules 1, including a steel barrel 101, a stirring blade 102 and a stirring motor 103 respectively. The stirring blade 102 and the stirring motor 103 are installed on the inner bottom side of the steel barrel 101, and are connected with the steel barrel 101 as a whole. ;

The weighing module 2 adopts an electronic weighing system, which can weigh the quality of the sample in the steel barrel in real time;

The water injection module 3 includes an overflow sensor 301, an overflow hole 302, a water tank 303, a water pump 304 and a water pipe 305. The water pump 304 extracts the water in the water tank 303 through the water pipe 305 and injects it into the steel bucket 101. The overflow hole 302 is located in the steel bucket 101. The barrel 101 is at the fixed height of the barrel wall;

The asphalt injection module 4 includes an asphalt pipe 401, an asphalt pump 402 and an asphalt tank 403. When the asphalt in the asphalt tank 403 is heated and in a flowing state, the asphalt pump 402 will pump out the asphalt and spray it into the steel drum along the asphalt pipe 401. 101;

The heating module 5 is composed of a steel barrel heating layer 501, a steel barrel temperature sensor 502, an asphalt tank heating layer 503 and an asphalt tank temperature sensor 504;

The control module 6 includes a switch 601, a power plug 602 and a control panel 603. The control panel 603 can collect and display detection data of each module and control other modules to work.

The stirring blade 102 is made of stainless steel, and the stirring motor 103 can drive the stirring blade 102 to stir the sample in the steel barrel.

An overflow sensor is installed on the overflow hole 302 to detect whether there is water overflow in the overflow hole 302 .

The weighing module 2 has thread grooves on the surface for fixing the steel barrel.

The steel barrel heating layer 501 and the asphalt tank heating layer 503 are heated by annular resistance wires surrounding the inner wall. The steel barrel temperature sensor 501 is attached to the stirring blade to measure the real-time temperature in the barrel, and the asphalt tank temperature sensor 503 is attached to the stirring blade. At the bottom of the asphalt tank, the real-time temperature of the asphalt in the asphalt tank is measured

The test method for measuring the theoretical maximum relative density of thermally regenerated asphalt mixture using the above-mentioned test device includes the following steps:

(1) Test preparation

①Turn on the power plug and turn on the switch 601, tighten and fix the steel barrels 101 on both sides on the weighing module 2 respectively, set the heating temperature to 25°C, weigh the mass of the steel barrels 101 as M ₁ , and start The water filling button on the control panel 603 fills the two steel barrels 101 with water, and when the water temperature in the barrels reaches 25°C, it is weighed, and the mass of water + barrels is recorded as M ₀ ;

②Pour out the water, and then screw the steel barrels 101 to the weighing module 2 respectively. After the water in the two steel barrels 101 is dried, test the two batches of the mixture to be tested with a mass of 2-4kg. The samples were respectively added to the steel barrel 101 and weighed, and the mass of the material + barrel was recorded as M ₂ ;

(2) Determination

① Set the heating temperature of the steel drum 101 and the asphalt tank 403. When the mixture in the drum and the asphalt in the asphalt tank 403 reach the set temperature, start the asphalt injection module 4, and the asphalt pump 402 will spray 1-2 kg of asphalt into The asphalt pipes 401 are sprayed into the steel drums 101 on both sides to ensure that the asphalt completely covers the asphalt mixture;

②Start the stirring module 1, stir at a speed of 50 r/min for 30 minutes, and then let it stand for 60 minutes; adjust the heating temperature of the steel barrels 101 on both sides to 25°C, and weigh when the temperature of the sample in the steel barrel 101 reaches 25°C. Module 2 weighs the material in the steel barrel + asphalt + barrel quality M ₃ ;

③ Start the water injection module 3, fill the steel barrel 101 with water, and when the water temperature in the barrel reaches 25°C, the weighing module 2 weighs the material in the steel barrel + asphalt + barrel + water quality M ₄ ;

④Enter the relative density of asphalt in the control panel _a . The control module automatically calculates the theoretical maximum relative density of the thermally recycled asphalt mixture according to the following formula. When the repeatability test error of the two samples is ≤ 0.011, the average value is taken as the final test result and displayed; large, the test should be repeated":

where: _t - theoretical maximum relative density of thermally recycled asphalt mixture, dimensionless;

M ₀ - mass of steel drum and water (g);

M ₁ - the mass of the steel drum (g);

M ₂ - the total mass (g) of the steel drum and the hot reclaimed asphalt mixture;

M ₃ - total mass (g) of steel drum, asphalt mixture and asphalt;

M ₄ - total mass (g) of steel drum, asphalt mixture, bitumen and water;

_a - Density of asphalt.

The heating temperature in the step (2) is 130°C if it is ordinary asphalt, and 160°C if it is modified asphalt.

The present invention has the following advantages:

(1) The test data is accurate and the error is small

In the present invention, asphalt is used as the medium, and it is added to the hot regenerated asphalt mixture, and by heating, stirring and standing, the asphalt can be fully immersed in each void of the mixture, and the air bubbles can be discharged. The volume of the mixture is very accurate; the test device contains two steel drums, and parallel tests of two samples can be carried out for the same hot recycled asphalt mixture at the same time to minimize the test error.

(2) The test process is environmentally friendly and harmless

The invention avoids the determination of old mineral materials, asphalt and other material indexes in the recycled asphalt pavement material, does not require extraction or combustion to remove the asphalt, avoids the damage to human body caused by toxic materials such as trichloroethylene, and also reduces environmental pollution;

(3) The test operation is simple and easy to master

The test device and test method of the invention accurately control the temperature of the sample, the water injection process and the injection of asphalt through various sensors, not only can the accuracy of the test data be improved, but also the test operation is simple and easy to operate, the test cost is saved, and the test method is also beneficial. wide-scale promotion and application.

Description of drawings

Fig. 1 is the perspective view of the test device;

Figure 2 is a schematic view of the side structure of the test device;

Figure 3 is a top view of the test device;

Figure 4 is a structural schematic diagram of a steel barrel;

Fig. 5 is the signal control flow chart;

In the figure: 1-stirring module; including: 101-steel barrel; 102-stirring blade; 103-stirring motor;

2- Weighing module;

3-water injection module; including: 301-overflow sensor; 302-overflow hole; 303-water tank; 304-water pump; 305-water pipe;

4- Asphalt injection module; including: 401- Asphalt pipe; 402- Asphalt pump; 403- Asphalt tank;

5-Heating module; including: 501-steel drum heating layer; 502-steel drum temperature sensor; 503-asphalt tank heating layer; 504-asphalt tank temperature sensor;

6-Control module; including: 601-switch; 602-power plug; 603-control panel.

Detailed ways

The present invention is further described below with reference to the accompanying drawings and specific embodiments.

As shown in Figures 1 to 4, the test device of the present invention is composed of a stirring module 1, a weighing module 2, a water injection module 3, an asphalt injection module 4, a heating module 5 and a control module 6; the bottom of the steel drum 101 has threaded protrusions , which can be fixed in the threaded groove on the weighing module 2. When the bottom of the groove is in contact with the bottom of the steel drum, the stirring module 1 and the temperature sensor 502 of the steel drum are connected to the control circuit and are controlled by the control module 6. The side wall of the barrel 101 is not in contact with the heating layer 501 of the steel barrel, and only the bottom is fixed on the weighing module 2 . The heating temperature on the control panel 603 is adjusted so that the steel drum 101 and the pitch tank 403 are maintained at the desired temperature. When the water injection button on the control panel 603 is pressed, the water injection module 3 works. When the water level in the bucket reaches the height of the overflow hole 302 , water injection is automatically stopped, and excess water flows into the water tank 303 from the overflow hole 302 . The two steel drums 101 are respectively filled with 1 to 2 kg mixed material samples, weighed by the weighing module 2 and the test start button on the control panel 603 is pressed. The signal control of each module is shown in Figure 5, and the measurement work is completed. The stirring action of the stirring module 1 makes the asphalt fully fill the open spaces of the mixture. Two sets of test measurements of 1# and 2# can be carried out at the same time, and finally the device automatically calculates the theoretical maximum relative density of asphalt mixture according to the formula.

Implementation of the test method:

In order to verify the reliability and beneficial effect of a test device and test method for measuring the theoretical maximum relative density of thermally regenerated asphalt mixture of the present invention, the present invention is further described in detail below with reference to the examples, but the present invention is not limited to the following examples.

Example 1

According to the technical scheme of the present invention, the present embodiment provides a test method for measuring the theoretical maximum relative density of thermally regenerated asphalt mixture, taking AC-20C type thermally regenerated asphalt mixture as an example, the specific implementation steps are as follows:

(1) Test preparation

①Turn on the power plug and turn on the switch, tighten the steel barrels on both sides to the weighing module, set the heating temperature to 25°C, take the weight of the steel barrel and record it as M ₁ , and activate the The water filling button fills the two steel buckets with water, and when the water temperature in the bucket reaches 25°C, it is weighed, and the mass of water + bucket is recorded as M ₀ ;

②Pour out the water, and then screw the steel barrels to the weighing module respectively. After the water in the two steel barrels is dried, add two samples of the mixture to be tested with a mass of 2-4kg. Steel barrels are weighed, and the mass of the material + barrel is recorded as M ₂ ;

(2) Determination

①Set the heating temperature of the barrel and the asphalt tank to 130°C. When the mixture in the barrel and the asphalt in the asphalt tank reach the set temperature, start the asphalt injection module, and the asphalt pump will deliver 1-2kg of road petroleum asphalt along the asphalt. The pipes are sprayed into the steel barrels on both sides to ensure that the asphalt completely covers the asphalt mixture;

②Start the stirring module, stir at a speed of 50r/min for 30 minutes, and then let it stand for 60 minutes; adjust the heating temperature of the steel barrels on both sides to 25°C, and when the temperature of the sample in the steel barrel reaches 25°C, the weighing module weighs Material in steel drum + asphalt + drum mass M ₃ ;

③ Start the water injection module, fill the steel bucket with water, and when the water temperature in the bucket reaches 25°C, the weighing module weighs the material in the steel bucket + asphalt + bucket + water mass M ₄ ;

④Enter the relative density of road petroleum asphalt in the control panel _a = 1.038, the theoretical maximum relative density of the hot recycled asphalt mixture is automatically calculated by the control module according to the following formula, the repeatability test error of the two samples is ≤ 0.011, and the average value is taken as the final test result and displayed.

where: _t - theoretical maximum relative density of thermally recycled asphalt mixture, dimensionless;

M ₀ - mass of steel drum and water (g);

M ₁ - the mass of the steel drum (g);

M ₂ - the total mass (g) of the steel drum and the hot reclaimed asphalt mixture;

M ₃ - total mass (g) of steel drum, asphalt mixture and asphalt;

M ₄ - total mass (g) of steel drum, asphalt mixture, bitumen and water;

_a - Relative density of asphalt.

At the same time, the theoretical maximum relative density of the thermally recycled asphalt mixture was determined by the vacuum method and the calculation method, and compared with the results obtained by the test method of the present invention, as shown in Table 1.

Table 1 Comparison of the measurement results of the theoretical maximum relative density of AC-20C type thermally recycled asphalt mixture

According to the measured value of theoretical maximum relative density obtained by each method, the optimal whetstone ratio was further determined. High-temperature rutting test, low-temperature bending test, water-immersion Marshall test and freeze-thaw splitting test were carried out respectively. The test results are shown in Table 2.

Table 2 Comparison of performance test results of AC-20C type thermally recycled asphalt mixture

Example 2

According to the technical scheme of the present invention, the present embodiment provides a test method for determining the theoretical maximum relative density of asphalt mixtures, taking AC-13C type modified thermally regenerated asphalt mixtures as an example, and the specific implementation steps are as follows:

(1) Test preparation

①Turn on the power plug and turn on the switch, tighten the steel barrels on both sides to the weighing module, set the heating temperature to 25°C, take the weight of the steel barrel and record it as M ₁ , and activate the The water filling button fills the two steel buckets with water, and when the water temperature in the bucket reaches 25°C, it is weighed, and the mass of water + bucket is recorded as M ₀ ;

②Pour out the water, and then screw the steel barrels to the weighing module respectively. After the water in the two steel barrels is dried, add two samples of the mixture to be tested with a mass of 2-4kg. Steel barrels are weighed, and the mass of the material + barrel is recorded as M ₂ ;

(2) Determination

①Set the heating temperature of the barrel and the asphalt tank to 160°C. When the mixture in the barrel and the asphalt in the asphalt tank reach the set temperature, start the asphalt injection module, and the asphalt pump will deliver 1-2kg of modified asphalt along the asphalt. The pipes are sprayed into the steel barrels on both sides to ensure that the asphalt completely covers the asphalt mixture;

②Start the stirring module, stir at a speed of 50r/min for 30 minutes, and then let it stand for 60 minutes; adjust the heating temperature of the steel barrels on both sides to 25°C, and when the temperature of the sample in the steel barrel reaches 25°C, the weighing module weighs Material in steel drum + asphalt + drum mass M ₃ ;

③ Start the water injection module, fill the steel bucket with water, and when the water temperature in the bucket reaches 25°C, the weighing module weighs the material in the steel bucket + asphalt + bucket + water mass M ₄ ;

④Enter the relative density of modified asphalt in the control panel _a = 1.042, the theoretical maximum relative density of the hot recycled asphalt mixture is automatically calculated by the control module according to the following formula, the repeatability test error of the two samples is ≤ 0.011, and the average value is taken as the final test result and displayed.

where: _t - theoretical maximum relative density of thermally recycled asphalt mixture, dimensionless;

M ₀ - mass of steel drum and water (g);

M ₁ - the mass of the steel drum (g);

M ₂ - the total mass (g) of the steel drum and the hot reclaimed asphalt mixture;

M ₃ - total mass (g) of steel drum, asphalt mixture and asphalt;

M ₄ - total mass (g) of steel drum, asphalt mixture, bitumen and water;

_a - Relative density of asphalt.

At the same time, the theoretical maximum relative density of the thermally recycled asphalt mixture was determined by the vacuum method and the calculation method, and compared with the results obtained by the test method of the present invention, as shown in Table 3.

Table 3 Comparison of theoretical maximum relative density test results of AC-13C type modified thermally recycled asphalt mixture

According to the measured value of theoretical maximum relative density obtained by each method, the optimal whetstone ratio was determined, respectively, high temperature rutting test, low temperature bending test, water immersion Marshall and freeze-thaw splitting test. The test results are shown in Table 4.

Table 4 Comparison of performance test results of AC-13C type modified thermally recycled asphalt mixture

The test results of the above embodiments show that: for the thermally regenerated asphalt mixture mixed with ordinary asphalt and modified asphalt, the test device and the test method of the present invention can accurately and stably measure its maximum theoretical relative density, and the parallel test error is small; Compared with other methods, the thermally recycled asphalt mixture determined according to the test results has better high temperature, low temperature and water stability performance, and all meet the specification requirements, indicating that this test method is more reasonable and the test results are more credible.

It should be noted that the above embodiment is only for understanding the present invention, and the present invention is not limited to this embodiment. Any addition, equivalent replacement or modification of technical features made on the basis of the technical solution of the present invention shall be regarded as the present invention. the scope of protection of the invention.

Claims (7)

1. a kind of experimental rig for measuring heat regeneration asphalt mixture theoretical maximum specific density, which is characterized in that by stirring mould Block (1), Weighing module (2), water injection module (3), pitch jet module (4), heating module (5) and control module (6) composition；

There are two the stirring modules (1), respectively includes steel bucket (101), stirring blade (102) and stirring motor (103), Stirring blade (102) and stirring motor (103) are installed on the internal bottom side of steel bucket (101), are linked together with steel bucket (101)；

The Weighing module (2) uses electronic weighing system, can weigh the quality of sample in steel bucket in real time；

The water injection module (3) includes spilling water sensor (301), spillway hole (302), sink (303), water pump (304) and water It manages (305), the water in sink (303) is withdrawn and fed into steel bucket (101) by water pump (304) through water pipe (305), spillway hole (302) it is located at steel bucket (101) bucket wall fixed height；

The pitch jet module (4) includes pitch pipe (401), bitumenpump (402) and Asphalt tank (403), to Asphalt tank (403) when the pitch heating in is in flow regime, bitumenpump (402) extracts pitch out, is injected into steel along pitch pipe (401) Tubbing (101)；

The heating module (5) is by steel bucket heating layer (501), steel barrel temperature sensor (502), Asphalt tank heating layer (503) it is formed with Asphalt tank temperature sensor (504)；

The control module (6) includes switch (601), attaching plug (602) and control panel (603), control panel (603) It can acquire and show the detection data of each module, and control other each modules and work.

2. experimental rig according to claim 1, which is characterized in that the stirring blade is that (102) are stainless steel Matter, stirring motor (103) can drive stirring blade (102) to be stirred the sample in steel bucket.

3. experimental rig according to claim 1, which is characterized in that be equipped with spilling water biography on the spillway hole (302) Sensor, can detecte whether spillway hole (302) has water spilling.

4. experimental rig according to claim 1, which is characterized in that there is thread groove on described Weighing module (2) surface, To fixed steel bucket.

5. experimental rig according to claim 1, which is characterized in that the steel bucket heating layer (501) and Asphalt tank Heating layer (503) is all made of the ring resistance silk heating around inner wall, and steel barrel temperature sensor (501) is attached to stirring blade In, real time temperature in bucket is measured, Asphalt tank temperature sensor (503) is attached to pitch trench bottom, measures pitch in Asphalt tank Real time temperature.

6. using the test side of experimental rig described in claim 1 measurement heat regeneration asphalt mixture theoretical maximum specific density Method, which is characterized in that include the following steps progress:

(1) test prepares

1. powering on plug and turning on the switch (601), the steel bucket (101) of two sides is tightened to Weighing module 2 respectively On, heating temperature is set as 25 DEG C, and the quality for weighing steel bucket (101) is denoted as M₁, starting control panel (603) on water filling press Button will fill water in two steel buckets (101), when inner bucket water temperature reaches 25 DEG C, weighs, water+bucket quality is denoted as M₀；

2. water is poured out, then steel bucket (101) is tightened to respectively on Weighing module (2) again, to two steel buckets (101) after interior moisture drying, the mixture sample to be measured that two parts of quality are 2~4kg is separately added into steel bucket (101) and is claimed Weight, is denoted as M for material+bucket quality₂；

(2) it measures

1. the heating temperature of steel bucket (101) and Asphalt tank (403) is set, in the mixture and Asphalt tank (403) in bucket When pitch reaches set temperature, start pitch jet module 4, bitumenpump (402) is by the pitch of 1~2kg mass along pitch pipe (401) it is injected into the steel bucket (101) of two sides, guarantees that pitch all covers asphalt；

2. starting stirring module 1 stirs 30min according to the revolving speed of 50r/min, then stands 60min；By two sides steel bucket (101) Heating temperature is adjusted to 25 DEG C, and when steel bucket (101) interior specimen temperature reaches 25 DEG C, Weighing module (2) is weighed in steel bucket Material+pitch+bucket mass M₃；

3. starting water injection module 3, water will be filled in steel bucket (101), when inner bucket water temperature is up to 25 DEG C, Weighing module (2) is weighed Material+pitch+bucket+water quality M in steel bucket₄；

4. inputting the relative density of pitch in control panel _a , heat regeneration asphalt is calculated by control module automatically as follows Mixture theoretical maximum specific density, when the repetitive test error of two parts of samples≤0.011, taking its average value is final examination It tests result and shows；Otherwise " error is excessive, should re-start test " is prompted:

In formula: _tHeat regeneration asphalt mixture theoretical maximum specific density, dimensionless；

M ₀ The quality (g) of steel bucket and water；

M ₁ The quality (g) of steel bucket；

M ₂The gross mass (g) of steel bucket and heat regeneration asphalt mixture；

M ₃The gross mass (g) of steel bucket, asphalt and pitch；

M ₄The gross mass (g) of steel bucket, asphalt, pitch and water；

_aThe density of pitch.

7. test method according to claim 6, which is characterized in that the heating temperature in the step (2), if common Pitch is then 130 DEG C；If modified pitch is then set as 160 DEG C.