A preparation method and evaluation method of a test piece for testing heavy metal element blocking performance of waste fly ash

Abstract

The present application belongs to the technical field of road material, and particularly relates to a preparation method and evaluation method of a test piece for testing the blocking performance of heavy metal elements in waste fly ash, wherein the preparation method comprises the following steps: mixing different amounts of waste fly ash material with asphalt material respectively, obtaining waste fly ash-asphalt mortar with different doping amounts through 7 steps, and finally obtaining the final test piece. The present application has the following advantages: 1. The present application prepares asphalt mortar pieces with different doping amounts, and then assembles and combines them, so as to analyze the sedimentation trend of waste fly ash in the test piece, and further analyze the blocking effect of the asphalt material. 2. The evaluation test of the present application can avoid the randomness of data, and accurately obtain the heavy metal element penetration under different layer quality tests and different working conditions, so as to objectively evaluate the blocking effect of the asphalt material on the waste fly ash.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road materials, in particular to a preparation method and evaluation method of a test piece for testing heavy metal element blocking performance of waste fly ash. BACKGROUND

[0002] Waste fly ash, as a high-toxicity waste incineration residue, enters the circulation system, and poses potential ecological risks to groundwater resources and the surrounding environment. In recent years, the existing disposal methods for waste fly ash have developed from cement solidification technology to chemical agent extraction technology, in order to reduce the free heavy metal elements in waste fly ash and achieve solidification and recycling of heavy metal elements. However, the current technical means are not mature enough to meet the growing demand for waste fly ash treatment. In order to effectively treat a large amount of accumulated waste fly ash, asphalt materials have attracted widespread attention due to their solidification effect on waste fly ash and availability.

[0003] The solidified waste fly ash asphalt binder has the advantages of small capacity, strong chemical stability, high waterproofness, etc. In addition, relevant research shows that the road performance of asphalt mortar is not limited by the use of waste fly ash doping amount, so it is feasible to use fly ash to replace ordinary fillers in asphalt construction materials. However, the blocking effect of asphalt materials on waste fly ash is affected by environmental factors and time, resulting in leaching and loss of heavy metal elements.

[0004] At the same time, during the evaluation of waste fly ash-asphalt mortar, the dispersion of waste fly ash in the cementing material during the placement process causes the bottom to accumulate. Different types of asphalt mortar have different wrapping performance and blocking performance for fly ash. When the wrapping performance of asphalt mortar for fly ash is good, the blocking performance of waste fly ash is good and there is no obvious bottom accumulation. However, there is no accurate method for evaluating the heavy metal element blocking performance of waste fly ash in the prior art.

[0005] Therefore, in view of the deficiencies in the prior art, it is necessary to provide a test piece preparation method for testing the heavy metal element blocking performance of waste fly ash and an evaluation method thereof to solve the deficiencies in the prior art. SUMMARY

[0006] One of the purposes of the present application is to provide a test piece preparation method for testing the heavy metal element blocking performance of waste fly ash to avoid the deficiencies in the prior art. The test piece obtained by the test piece preparation method for testing the heavy metal element blocking performance of waste fly ash can prepare a combination block with different doping amount distribution, so as to investigate the wrapping performance of asphalt materials for fly ash.

[0007] The above purpose of the present application is achieved by the following technical measures:

[0008] A test piece preparation method for testing the heavy metal element blocking performance of waste fly ash is provided, which is prepared by the following steps:

[0009] Step (1), different amounts of waste fly ash material are respectively mixed with asphalt material to obtain waste fly ash-asphalt mortar with different doping amounts, and the inside and bottom of the multiple sub-molds and the total mold are brushed with release agent;

[0010] Step (2), melt and fill the inside of the multiple sub-molds with waste fly ash-asphalt mortar with different doping amounts, and then perform cooling treatment;

[0011] Step (3), after solidification, the waste fly ash-asphalt mortar with different doping amounts is demolded to obtain multiple asphalt mortar sub-pieces;

[0012] Step (4), the multiple asphalt mortar sub-pieces are assembled to obtain a combined block, and then the combined block is placed in the total mold;

[0013] Step (5), melt the asphalt into the total mold to fill the pores of the combined block, and obtain an asphalt precast test piece;

[0014] Step (6), heat the asphalt precast test piece and the total mold as a whole until the surface temperature of the asphalt is constant at the target temperature, and then the heating treatment is completed;

[0015] Step (7), the asphalt precast test piece and the total mold are cooled, and finally the asphalt precast test piece is taken out to obtain the final test piece.

[0016] Preferably, the sub-mold includes one cylindrical sub-mold, β circular ring-shaped sub-molds, and one cylindrical sub-mold, and 2≤β≤10.

[0017] Preferably, the asphalt mortar sub-piece includes one cylindrical sub-piece corresponding to the cylindrical sub-mold, β circular ring-shaped sub-pieces corresponding to the circular ring-shaped sub-mold, and one cylindrical sub-piece corresponding to the cylindrical sub-mold.

[0018] The height of the circular ring-shaped sub-piece is defined as α, the height of the cylindrical sub-piece and the height of the cylindrical sub-piece are both α×β, and 1cm≤α≤10cm.

[0019] Preferably, the outer diameter of the cylindrical sub-piece is equal to the inner diameter of the circular ring-shaped sub-piece, and the outer diameter of the cylindrical sub-piece is equal to the outer diameter of the circular ring-shaped sub-piece.

[0020] Preferably, the assembly method of the combined block is to stack multiple circular ring-shaped sub-pieces in order from high to low doping amount, and the cylindrical sub-piece is sleeved on the center of the stacked circular ring-shaped sub-pieces, and the cylindrical sub-piece is sleeved on the outer periphery of the stacked circular ring-shaped sub-pieces, thereby forming a columnar combined block.

[0021] Preferably, the doping amount of the cylindrical sub-piece is the largest.

[0022] Preferably, the doping amount of the cylindrical sub-piece is the smallest.

[0023] Preferably, the doping amounts of the annular sub-pieces are not all the same, and the doping amounts of all the annular sub-pieces are less than the doping amount of the cylindrical sub-piece and greater than the doping amount of the cylindrical sub-piece; in the annular sub-pieces, there are at least two cylindrical sub-pieces with the same doping amount.

[0024] In the step (1), the doping amount of the garbage fly ash-asphalt mortar is 0%-20%, and the mixing condition is that the mixing is performed in a high-speed shear instrument at a shear rate of 3000 rad / min and a shear time of 15 min.

[0025] Preferably, the cooling treatment is performed at -20℃±2℃ for 30 min-60 min.

[0026] In the step (6), when the asphalt material added in the step (1) is base asphalt, the heating treatment is performed to a target temperature of 110℃; when the asphalt material added in the step (1) is modified asphalt, the heating treatment is performed to a target temperature of 130℃.

[0027] Preferably, the diameter of the cylindrical sub-piece is 2 cm and the height is 12 cm.

[0028] Preferably, the inner diameter of the annular sub-piece is 2 cm, the outer diameter is 10 cm, and the height is 2 cm.

[0029] Preferably, the inner diameter of the cylindrical sub-piece is 10 cm, the outer diameter is 12 cm, and the height is 12 cm.

[0030] Preferably, the cylindrical sub-mold is a two-piece semicylindrical steel pipe with a base and a circular lock, and the inner diameter of the steel pipe is 2 cm, the outer diameter is 2.5 cm, the height is 12.2 cm, the inner diameter of the circular lock is 2.5 cm, the outer diameter is 3 cm, the diameter of the base is 3 cm, the thickness is 0.5 cm, and the groove depth is 0.2 cm.

[0031] Preferably, the annular sub-mold is a double-layer annular steel pipe with a base, the inner diameter of the large annular ring is 10 cm, the outer diameter is 10.5 cm, the height is 2.2 cm, the inner diameter of the small annular ring is 1.5 cm, the outer diameter is 2 cm, the height is 2.2 cm, the diameter of the base is 12 cm, the thickness is 0.5 cm, and the groove depth is 0.2 cm.

[0032] Preferably, the above-mentioned cylindrical split-mold is a double-layered annular steel pipe with a base, the large annular ring of which has an inner diameter of 12 cm, an outer diameter of 13 cm, and a height of 12.2 cm, the large annular ring of which has an inner diameter of 9 cm, an outer diameter of 10 cm, and a height of 12.2 cm, and the base of which has a diameter of 14 cm, a thickness of 0.5 cm, and a groove depth of 0.2 cm.

[0033] Preferably, the above-mentioned total mold is a steel cylindrical pipe with a base, the pipe of which has an outer diameter of 12.5 cm, an inner diameter of 12 cm, and a height of 12.2 cm, and the base of which has a diameter of 14 cm and a height of 2 cm, and the base of which has a positioning needle at the center thereof, and the positioning needle has a diameter of 1 mm and a height of 5 cm.

[0034] In the step (1), the doping amount of the fly ash-bitumen mortar is 15%, 13%, 10%, 7%, and 0%, wherein the doping amount of the cylindrical split-piece is 0%, the doping amount of the cylindrical split-piece is 15%, the doping amount of the two annular split-pieces is 13%, the doping amount of the two annular split-pieces is 10%, and the doping amount of the two annular split-pieces is 7%.

[0035] Another object of the present application is to provide an evaluation method of a test piece to avoid the shortcomings of the prior art. The evaluation method can objectively evaluate the heavy metal element penetration of the fly ash-bitumen mortar and the shielding effect of the bitumen binder on the heavy metal elements of the fly ash from waste incineration under different working conditions.

[0036] The above-mentioned objects of the present application are achieved by the following technical measures:

[0037] The evaluation method of the test piece is provided, which comprises bitumen unit mass testing of different layers of the test piece and heavy metal element penetration testing under different working conditions.

[0038] Preferably, the bitumen unit mass testing of different layers is performed by the following steps:

[0039] Step a1, from the axial height direction, the thickness of each layer is α, from top to bottom, the test piece is cut into β parts to obtain β cut pieces;

[0040] Step a2, weigh the β mass measurement containers respectively to obtain M 0-1 , …, M 0-i , …, M 0-β , 2≤i≤β; meanwhile, the β cut pieces are heated and melted, and then respectively poured into the corresponding β mass measurement containers, and the liquid level is higher than the edge of the mass measurement container, and the volume of the mass measurement container is smaller than the volume of the cut piece, and the volumes of all the mass measurement containers are equal;

[0041] Step a2: Cool all the mass measuring containers and the internal cutting parts to room temperature. Use a scraper to smooth the asphalt surface along the edge of the mass measuring container. Weigh the mass measuring containers again to obtain M. 2-1 ... M 2-i ... M 2-β ;

[0042] Step a3: Calculate the unit mass in β of the mass measuring containers according to formula (I), and then calculate the maximum difference M according to formula (II). 2-max When M 2-max The specimen preparation quality is qualified when the weight is ≤0.05g;

[0043] M 2-i =M 1-i —M 0-I ...Formula (I);

[0044] M 2-max =Max{M 2-i}—Min{M 2-i Equation (II) ...

[0045] Preferably, the heavy metal element solubility test under the above different working conditions includes upper immersion condition, lower immersion condition and full immersion condition;

[0046] The above-ground immersion condition is carried out by the following steps:

[0047] Step b1: Use a plastic sleeve that matches the diameter of the test piece, then put the upper part of the test piece over it so that the plastic sleeve contacts the test piece, with the contact height being 1cm. Then, use clamps to tighten the plastic sleeve in the overlapping area.

[0048] Step b2: Seal the inside of the plastic sleeve that is in contact with the test piece using paraffin wax;

[0049] Step b3: Fill the plastic sleeve with the leaching solution and allow the liquid to overflow. Then seal the plastic sleeve with plastic wrap and seal the top of the plastic sleeve with the cap. Keep the test piece and the plastic sleeve at a constant temperature of 60°C for 16-28 hours.

[0050] Step b3: Take out the solution and define it as solution P1;

[0051] The lower immersion condition is carried out by the following steps:

[0052] Step c1, using a plastic sleeve matching the diameter of the test piece, then the lower part of the test piece is sleeved, the contact part of the plastic sleeve with the test piece is 1 cm high, and the clamp is tightened to overlap the plastic sleeve;

[0053] Step c2, using paraffin to seal the inside of the plastic sleeve in contact with the test piece;

[0054] Step c3, fill the plastic sleeve with leaching solution, and let the liquid surface escape, then seal the plastic sleeve with plastic wrap, and seal the top with the cover of the plastic sleeve, finally invert the test piece, and store the test piece and the plastic sleeve at 60°C for 16-28 hours;

[0055] Step c3, take out the leaching solution and define it as leaching solution P3;

[0056] The whole immersion condition is carried out by the following steps:

[0057] Step d1, take an immersion container with a volume greater than the test piece, and the diameter of the immersion container is greater than the diameter of the test piece, and the fixed needle is fixedly assembled in the immersion container;

[0058] Step d2, insert the fixed needle along the central axis into the bottom center of the test piece, so that the bottom of the test piece is at a height of α from the bottom surface of the immersion container;

[0059] Step d3, fill the inside of the immersion container with leaching solution, so that the top surface of the test piece is below the height α of the leaching solution, and store the test piece and the immersion container at 60°C for 16-28 hours;

[0060] Step d3, take out the leaching solution and define it as leaching solution P2.

[0061] In the heavy metal element leaching test under different conditions, leaching solutions P1, P2 and P3 are filtered and diluted 100 times respectively.

[0062] Preferably, the leaching difference in the heavy metal element leaching test under different conditions is evaluated by the area S a The index is evaluated as shown in formula (III):

[0063] S a =P2-0.5P1-0.5P3…… formula (III).

[0064] Preferably, the heavy metal element leaching in the heavy metal element leaching test under different conditions is evaluated by the area S b The index is evaluated as shown in formula (IV):

[0065] S b =P1+P3……Equation (Ⅳ).

[0066] Preferably, the inhibitory effect of asphalt on the migration and leaching of heavy metal elements in waste fly ash and its heavy metal elements under the above-mentioned heavy metal element solubility test under different working conditions is expressed by the total envelope area S of the curve. c The indicators are used for evaluation, as shown in equation (V):

[0067] S c =S a +S b =P2+0.5P1+0.5P3……Equation (V);

[0068] Preferably, the above-mentioned mass measuring container is a cylindrical container with an inner diameter of 55 mm and a depth of 35 mm.

[0069] Preferably, the aforementioned plastic sleeve is a cylindrical container with a diameter of 12.1 cm and a height of 6 cm.

[0070] Preferably, the above-mentioned immersion container is a cylindrical container with a diameter of 16cm and a height of 16cm.

[0071] The application provides a preparation method of a test piece for testing the blocking performance of heavy metal elements in garbage fly ash and an evaluation method thereof, wherein the test piece is prepared by the following steps: step (1), stirring and mixing different amounts of garbage fly ash materials with asphalt materials to obtain garbage fly ash-asphalt mortar with different doping amounts, and brushing release agents on the inside and bottom of a plurality of sub-molds and a total mold; step (2), melting and filling the inside of the plurality of sub-molds with the garbage fly ash-asphalt mortar with different doping amounts, and then performing cooling treatment; step (3), after solidification, the garbage fly ash-asphalt mortar with different doping amounts is demolded to obtain a plurality of asphalt mortar sub-pieces; step (4), the plurality of asphalt mortar sub-pieces are assembled to obtain an assembly block, and then the assembly block is placed in the total mold; step (5), molten asphalt is added to the total mold to fill the pores of the assembly block, and an asphalt precast test piece is obtained; step (6), the asphalt precast test piece and the total mold are heated as a whole until the temperature of the asphalt surface is constant at a target temperature, and then the heating treatment is completed; step (7), the asphalt precast test piece and the total mold are cooled, and finally the asphalt precast test piece is taken out to obtain a final test piece. The beneficial effects of the application are as follows: 1. The application assembles the asphalt mortar sub-pieces with different doping amounts to analyze the precipitation trend of the garbage fly ash in the test piece, and then analyzes the blocking effect of the asphalt material. 2. The evaluation test of the application can avoid the randomness of the data, accurately obtain the heavy metal element dissolution and penetration under different layer quality tests and different working conditions, and objectively evaluate the blocking effect of the asphalt material on the garbage fly ash. BRIEF DESCRIPTION OF DRAWINGS

[0072] The application is further described with reference to the accompanying drawings, but the content of the drawings does not constitute any limitation on the application.

[0073] Figure 1 It is a structural schematic diagram of a cylindrical sub-mold.

[0074] Figure 2 It is a structural schematic diagram of a cylindrical sub-piece in a cylindrical sub-mold.

[0075] Figure 3 It is a structural schematic diagram of a circular ring-shaped sub-mold.

[0076] Figure 4 It is a structural schematic diagram of a circular ring-shaped sub-piece in a circular ring-shaped sub-mold.

[0077] Figure 5 It is a structural schematic diagram of a cylindrical sub-mold.

[0078] Figure 6 It is a structural schematic diagram of a cylindrical sub-piece in a cylindrical sub-mold.

[0079] Figure 7 Fig. 1 is a structural schematic diagram of a total mold.

[0080] Figure 8 Fig. 2 is a structural schematic diagram of a combination block inside the total mold.

[0081] Figure 9 Fig. 3 is a sectional schematic diagram of the combination block.

[0082] Figure 10 Fig. 4 is a state diagram of the combination block and the plastic sleeve in a lower water immersion working condition.

[0083] Figure 11 Fig. 5 is a state diagram of the combination block and the plastic sleeve in an upper water immersion working condition.

[0084] Figure 12 Fig. 6 is a state diagram of the combination block and the water immersion container in a full water immersion working condition.

[0085] Figure 13 Fig. 7 is an index schematic diagram of heavy metal Zn element leaching evaluation of test pieces 7, 11 and 15 in Example 3.

[0086] Figure 14 Fig. 8 is an index schematic diagram of heavy metal Fe element leaching evaluation of test pieces 19, 23 and 27 in Example 3.

[0087] In the Figures 1 to 14 , comprising:

[0088] Cylindrical sub-mold 100, annular sub-mold 200, cylindrical sub-mold 300, total mold 400, cylindrical sub-piece 500, annular sub-piece 600, cylindrical sub-piece 700, test piece 800, plastic sleeve 900, water immersion container 1000. DETAILED DESCRIPTION

[0089] The technical solutions of the present application are further described in combination with the following examples. The experimental methods in the following examples are all conventional methods unless otherwise specified. The raw materials, reagent materials and the like used in the following examples can be purchased from conventional biochemical reagent stores or pharmaceutical business enterprises unless otherwise specified.

[0090] Example 1

[0091] A test piece preparation method for testing the barrier performance of heavy metal elements in fly ash, as shown in Figures 1 to 9 , is prepared by the following steps:

[0092] Step (1), different amounts of fly ash materials are respectively mixed with asphalt materials, corresponding to obtain a plurality of doped amounts of fly ash-asphalt mortar, and at the same time, the inside and bottom of a plurality of sub-molds and the total mold 400 are brushed with release agent;

[0093] Step (2), melt and fill the inside of the corresponding plurality of sub-molds with a plurality of doped amounts of garbage fly ash-asphalt mortar, and then perform a cooling treatment;

[0094] Step (3), after solidification, the plurality of doped amounts of garbage fly ash-asphalt mortar are demolded respectively, and a plurality of different doped amounts of asphalt mortar sub-pieces are obtained;

[0095] Step (4), the plurality of asphalt mortar sub-pieces are assembled to obtain an assembled block, and then the assembled block is placed in the total mold 400;

[0096] Step (5), melt asphalt is added to the total mold 400 to fill the pores of the assembled block, and an asphalt precast test piece is obtained;

[0097] Step (6), the asphalt precast test piece and the total mold 400 are heated as a whole, and the heating treatment is completed when the asphalt surface temperature continuously and constantly reaches the target temperature;

[0098] Step (7), the asphalt precast test piece and the total mold 400 are cooled, and finally the asphalt precast test piece is taken out to obtain the final test piece 800.

[0099] It should be noted that in step (1), 100g of base asphalt material is used in each doped amount of garbage fly ash-asphalt mortar, and a corresponding amount of garbage fly ash is added, and the release agent is specifically dimethyl silicone oil. In step (2), the molten garbage fly ash-asphalt mortar is higher than the edge of the sub-mold when being poured into the sub-mold. In step (3), a preheated 160℃ scraper is used to scrape the surface in front of the mold, and then a push-pull method is used to demold the garbage fly ash-asphalt mortar. In step (5), 120℃ melt asphalt is used for pore filling. In step (6), a heat insulation pad made of ceramic fiber is placed on the bottom surface of the total mold 400 and then heated, and the continuously constant target temperature of the present application can be set according to the actual situation, such as the target temperature being unchanged within 3min. It should be noted that the asphalt material of the present application includes SBS modified asphalt, 90# base asphalt, 70# base asphalt, etc.

[0100] The mold includes one cylindrical mold 100, beta ring-shaped molds 200, and one cylindrical mold 300, and 2≤β≤10; the asphalt mortar sub-device includes one cylindrical sub-device 500 corresponding to the cylindrical mold 100, beta ring-shaped sub-devices 600 corresponding to the ring-shaped molds 200, and one cylindrical sub-device 700 corresponding to the cylindrical mold 300. The height of the ring-shaped sub-device 600 is defined as alpha, the height of the cylindrical sub-device 500 and the height of the cylindrical sub-device 700 are both alpha*beta, and 1cm≤alpha≤10cm. The outer diameter of the cylindrical sub-device 500 is equal to the inner diameter of the ring-shaped sub-device 600; the outer diameter of the cylindrical sub-device 700 is equal to the outer diameter of the ring-shaped sub-device 600.

[0101] The combination block is formed by stacking the ring-shaped sub-devices 600 in the order of decreasing doping amount, and the cylindrical sub-device 500 is sleeved on the center of the stacked ring-shaped sub-devices 600, and the cylindrical sub-device 700 is sleeved on the outer periphery of the stacked ring-shaped sub-devices 600.

[0102] The doping amount of the cylindrical sub-device 700 is the largest, the doping amount of the cylindrical sub-device 500 is the smallest, the doping amounts of all the ring-shaped sub-devices 600 are not all the same, and the doping amounts of all the ring-shaped sub-devices 600 are less than the doping amount of the cylindrical sub-device 500 and greater than the doping amount of the cylindrical sub-device 700. In the ring-shaped sub-device 600, there are at least two cylindrical sub-devices 500 with the same doping amount.

[0103] It should be noted that the force receiving surface in contact with the placed object when the combination block is normally placed is defined as the lower bottom surface.

[0104] The ring-shaped sub-devices 600 are stacked in the order of decreasing doping amount, which is beneficial to downward diffusion under normal circumstances, and is beneficial to downward diffusion if the wrapping performance of the asphalt material on the fly ash is poor, so as to more accurately evaluate the blocking effect of the asphalt material.

[0105] The distribution of the doping amounts of the cylindrical sub-device 700, the cylindrical sub-device 500, and the ring-shaped sub-device 600 reduces the measurement error of the heavy metal element solubility test under different working conditions. The presence of at least two cylindrical sub-devices 500 with the same doping amount reduces the doping amount error.

[0106] In step (1), the fly ash of garbage-asphalt mortar doping amount is 0%-20%, the stirring mixing condition is that the shearing rate is 3000 rad / min in the high-speed shearing instrument, and the shearing time is 15 min for stirring mixing. The cooling treatment is 30 min-60 min at-20℃±2℃, wherein the role of the cooling treatment is to make the asphalt material low-temperature solidification, thereby preventing the fly ash from precipitating.

[0107] It should be noted that the actual optimal doping amount of fly ash of garbage-asphalt mortar is 10%-25%, so the fly ash of garbage-asphalt mortar of the present application is 0%-20%, which can match the actual fly ash of garbage-asphalt mortar.

[0108] In step (6), when the asphalt material added in step (1) is base asphalt, the heating treatment is to the target temperature of 110℃; when the asphalt material added in step (1) is modified asphalt, the heating treatment is to the target temperature of 130℃.

[0109] The test piece preparation method of the heavy metal element blocking performance of the fly ash of garbage can be prepared by preparing different doping amounts of asphalt mortar pieces and then assembling them, so as to analyze the precipitation trend of the fly ash of garbage in the test piece 800, and further analyze the blocking effect of the asphalt material.

[0110] Example 2

[0111] A test piece preparation method of the heavy metal element blocking performance of the fly ash of garbage, other features are the same as example 1, the difference is that:

[0112] The specific parameters of the cylindrical piece 700, the annular piece 600 and the cylindrical piece 500 of the present embodiment are as follows:

[0113] The diameter of the cylindrical piece 500 is 2 cm and the height is 12 cm; the inner diameter of the annular piece 600 is 2 cm, the outer diameter is 10 cm and the height is 2 cm; the inner diameter of the cylindrical piece 700 is 10 cm, the outer diameter is 12 cm and the height is 12 cm.

[0114] The corresponding parameters of the cylindrical mold 300, the annular mold 200, the cylindrical mold 100 and the total mold 400 corresponding to the above cylindrical piece 700, the annular piece 600 and the cylindrical piece 500 are as follows:

[0115] The cylindrical split mold 100 is a two-piece half-cylindrical steel pipe with a base and a circular hoop lock, and the inner diameter of the steel pipe is 2 cm, the outer diameter is 2.5 cm, and the height is 12.2 cm, the inner diameter of the circular hoop lock is 2.5 cm, the outer diameter is 3 cm, the diameter of the base is 3 cm, the thickness is 0.5 cm, and the groove depth is 0.2 cm.

[0116] The circular ring split mold 200 is a double-layer circular ring steel pipe with a base, the inner diameter of the large circular ring is 10 cm, the outer diameter is 10.5 cm, and the height is 2.2 cm, the inner diameter of the small circular ring is 1.5 cm, the outer diameter is 2 cm, and the height is 2.2 cm, the diameter of the base is 12 cm, the thickness is 0.5 cm, and the groove depth is 0.2 cm.

[0117] The cylindrical split mold 300 is a double-layer circular ring steel pipe with a base, the inner diameter of the large circular ring is 12 cm, the outer diameter is 13 cm, and the height is 12.2 cm, the inner diameter of the large circular ring is 9 cm, the outer diameter is 10 cm, and the height is 12.2 cm, the diameter of the base is 14 cm, the thickness is 0.5 cm, and the groove depth is 0.2 cm.

[0118] The total mold 400 is a steel cylindrical pipe with a base, the outer diameter of the pipe is 12.5 cm, the inner diameter is 12 cm, and the height is 12.2 cm, the size of the base is diameter 14 cm and height 2 cm, there is a positioning needle at the center of the base, and the diameter of the positioning needle is 1 mm and the height is 5 cm.

[0119] In step (1), the doping amount of waste fly ash-asphalt mortar is 15%, 13%, 10%, 7% and 0%, among which the doping amount of the cylindrical split piece 500 is 0%, the doping amount of the cylindrical split piece 700 is 15%, the doping amount of the two circular ring split pieces 600 is 13%, the doping amount of the two circular ring split pieces 600 is 10%, and the doping amount of the two circular ring split pieces 600 is 7%.

[0120] It should be noted that the thickness of the annular part 600 prepared by the cylindrical parting mold 300 of the embodiment is only 1 cm, and the annular ring of the annular part 600 is 4 cm, so that the influence of the annular part 600 on the solution liquid can be reduced in the subsequent upper water immersion condition and lower water immersion condition. At the same time, the doping amount of the annular part 600 is 13%, 10% and 7%, and there is a doping amount gradient, which is beneficial to the diffusion of the fly ash and the final doping amount is maintained at about 10%. The reason why the doping amount of the cylindrical part 700 is 15% is that the fly ash inside the cylindrical part 700 will diffuse to the inside, so that the final doping amount of the cylindrical part 700 can also be maintained at about 10%. At the same time, the doping amount of the cylindrical part 700 is 15%, and there is a small concentration difference between the doping amount of 13% and the doping amount of 7%, which is beneficial to the construction of the evaluation index, and will not have a great influence on the upper water immersion condition and the lower water immersion condition, so as to avoid the occurrence of errors.

[0121] Compared with example 1, the test piece 800 obtained in the embodiment has smaller error in the subsequent evaluation method.

[0122] Example 3

[0123] An evaluation method of a test piece, using the test piece prepared by the fly ash heavy metal element blocking performance test piece preparation method of example 2, wherein the asphalt material in the prepared test piece 800 is 70# base asphalt, and the fly ash material is Dongguan fly ash.

[0124] The evaluation method of the embodiment includes unit mass test of different layers of asphalt of the test piece 800 and heavy metal element solution permeability test under different working conditions.

[0125] The unit mass test of different layers of asphalt is performed by the following steps:

[0126] Step a1, from the axial height direction, cut the test piece 800 into β parts with the thickness of each layer as α from top to bottom;

[0127] Step a2, weigh the β mass measurement containers respectively to obtain M 0-1 , ……, M 0-i , ……, M 0-β , 2≤i≤β; meanwhile, melt the β cut pieces respectively, then pour them into the corresponding β mass measurement containers respectively, and make the liquid level higher than the edge of the mass measurement container, and the volume of the mass measurement container is smaller than the volume of the cut piece, and the volumes of all the mass measurement containers are equal;

[0128] Step a2, all mass measurement containers and the cutting pieces inside are cooled, then restored to room temperature, the scraper is used to scrape the asphalt surface along the edge of the cutting piece mass measurement container, the mass measurement container is weighed again, and M is obtained 2-1 , …, M 2-i , …, M 2-β ;

[0129] Step a3, the unit mass in the beta mass measurement containers is calculated according to formula (I), and then the maximum difference M is calculated according to formula (II) 2-max , when M 2-max ≤0.05g, the sample preparation quality is qualified.

[0130] M 2-i =M 1-i —M 0-I …… formula (I);

[0131] M 2-max =Max{M 2-i}—Min{M 2-i}…… formula (II).

[0132] The heavy metal element solubility test under different working conditions of the application includes upper immersion working condition, lower immersion working condition and full immersion working condition.

[0133] It should be noted that the scraper of the application needs to be preheated to 160 DEG C.

[0134] The upper immersion working condition is performed by the following steps:

[0135] Step b1, a plastic sleeve 900 matched with the diameter of the test piece 800 is used, then the upper part of the test piece 800 is sleeved, the plastic sleeve 900 is in contact with the test piece 800, the contact part height is 1cm, and then the clamp is used to clamp the plastic sleeve 900 in the overlapping area;

[0136] Step b2, the inside of the plastic sleeve 900 in contact with the test piece 800 is sealed by using paraffin;

[0137] Step b3, the leaching liquid is filled in the plastic sleeve 900, and the liquid surface is escaped, then the plastic sleeve 900 is sealed by using the preservative film, the cover of the plastic sleeve 900 is used to seal the top, and the test piece 800 and the plastic sleeve 900 are stored at 60 DEG C for 16h-28h.

[0138] Step b3, the solubility liquid is taken out and defined as solubility liquid P1.

[0139] The lower immersion working condition is performed by the following steps:

[0140] Step c1, use a plastic sleeve 900 matched with the diameter of the test piece 800, then put the lower part of the test piece 800 into the plastic sleeve 900, so that the plastic sleeve 900 is in contact with the test piece 800, and the contact part has a height of 1 cm, and then the clamp clamps the plastic sleeve 900 in the overlapping area;

[0141] Step c2, use paraffin to seal the inside of the plastic sleeve 900 in contact with the test piece 800;

[0142] Step c3, fill the plastic sleeve 900 with leaching liquid, and make the liquid level escape, then seal the plastic sleeve 900 with plastic wrap, and seal the top with the cover of the plastic sleeve 900, finally invert the test piece 800, and store the test piece 800 and the plastic sleeve 900 at 60 DEG C for 16-28 h;

[0143] Step c3, take out the leaching liquid and define it as leaching liquid P3.

[0144] Wherein, all the water immersion conditions are carried out by the following steps:

[0145] Step d1, take a water immersion container 1000 with a volume greater than the test piece 800, and the diameter of the water immersion container 1000 is greater than the diameter of the test piece 800, and the fixed needle is fixedly assembled in the water immersion container 1000;

[0146] Step d2, insert the fixed needle along the central axis into the bottom center of the test piece 800, so that the bottom of the test piece 800 is at a height of alpha from the bottom surface of the water immersion container 1000;

[0147] Step d3, fill the water immersion container 1000 with leaching liquid, so that the top surface of the test piece 800 is lower than the height alpha of the leaching liquid, and store the test piece 800 and the water immersion container 1000 at 60 DEG C for 16-28 h;

[0148] Step d3, take out the leaching liquid and define it as leaching liquid P2.

[0149] It should be noted that the leaching liquid of the embodiment is dilute nitric acid with pH = 3.

[0150] According to the standards of “Hazardous Waste Identification Standard Leaching Toxicity Identification” (GB 5085.3-2007) and “Technical Specification for Pollution Control of Domestic Waste Incineration Fly Ash” (HJ 1134-2020), the content of heavy metal elements is tested by inductively coupled plasma mass spectrometry to obtain parameter indexes P1, P2 and P3. Among them, the leaching liquid P1, the leaching liquid P2 and the leaching liquid P3 are filtered by a membrane filter and diluted 100 times in the heavy metal element leaching test under different conditions. The membrane filter is 0.45 μm.

[0151] The difference in the solubility of heavy metal elements under different working conditions is evaluated by using the envelope area S at the top of the curve a The index is evaluated as shown in formula (III):

[0152] S a =P2-0.5P1-0.5P3…… formula (III)

[0153] The heavy metal element leaching property of the heavy metal element solubility test under different working conditions is evaluated by using the envelope area S at the bottom of the curve b The index is evaluated as shown in formula (IV):

[0154] S b =P1+P3…… formula (IV)

[0155] The retardation effect of the asphalt on the migration and leaching of the waste fly ash and the heavy metal elements thereof is evaluated by using the total envelope area S of the curve under different working conditions c The index is evaluated as shown in formula (V):

[0156] S c =S a +S b =P2+0.5P1+0.5P3…… formula (V)

[0157] The quality measuring container is a cylindrical container, and the inner diameter thereof is 55 mm and the depth thereof is 35 mm;

[0158] The plastic sleeve 900 is a cylindrical container, and the diameter thereof is 12.1 cm and the height thereof is 6 cm;

[0159] The water immersion container 1000 is a cylindrical container, and the diameter thereof is 16 cm and the height thereof is 16 cm.

[0160] According to the parameters of the embodiment, 28 same test pieces 800 are prepared by using the preparation method of Example 2, in order to reduce the error, four test pieces 800 are used for unit mass testing of different layer bitumen at the same time, and Table 1 is obtained.

[0161] Table 1 Physical index of asphalt cement material test specimen preparation quality in Example 2

[0162]

[0163] The present application relates to test specimen preparation quality evaluation, which mainly analyzes the dispersibility of waste fly ash in asphalt cement, specifically tests the unit mass of different layer bitumen, and the data analysis in Table 1 shows that the M 2-max of the four test pieces 800 is less than or equal to 0.05 g, which indicates that the wrapping performance of the asphalt cement of the embodiment on the waste fly ash is better.

[0164] In the Zn element solubility test under different working conditions, in order to reduce the error, 4 test pieces 800 are used for each working condition, and according to the definition of the solubility P1, P2, P3 parameter indexes of the heavy metal element Zn of the asphalt cementing material under different working conditions, the evaluation index envelope area S is calculated a 、S b 、S c . The results are shown in Table 2 and Figure 13 .

[0165] Table 2 Zn element content detection results and indexes of fly ash asphalt mortar in Example 3

[0166]

[0167] In the Fe element solubility test under different working conditions, in order to reduce the error, 4 test pieces 800 are used for each working condition, the inductively coupled plasma mass spectrometry is used to extract the heavy metal element of the asphalt mortar, and according to the definition of the solubility P1, P2, P3 parameter indexes of the heavy metal element Fe of the asphalt cementing material under different working conditions, the evaluation index envelope area S is calculated a 、S b 、S c , and the results are shown in Table 3 and Figure 14 .

[0168]

[0169] According to the data analysis of Tables 2 and 3, the content of heavy metals Zn and Fe under different working conditions is tested by using the evaluation method involved in the application, and according to the data of the examples, the upper envelope area S a is introduced to evaluate the dispersion uniformity of the garbage fly ash in the asphalt and the solubility difference under different working conditions, the lower envelope area S b is introduced to evaluate the heavy metal element leaching of the garbage fly ash-asphalt mortar, and the total envelope area S c is introduced to evaluate the retardation effect of the asphalt on the migration and leaching of the garbage fly ash and the heavy metal elements thereof.

[0170] As Figure 13 and Figure 14 shown, the top envelope area S a of the index curve is the area of the figure connected by P1, P2 and P3 points, and the larger S a indicates that the heavy metal element leaching difference under different working conditions is larger, the garbage fly ash is more unevenly distributed in the asphalt, and the retardation effect of the asphalt on the migration of the heavy metal elements is worse.

[0171] The top envelope area S bS is the area of the figure enclosed by the connecting line of P1 point and P3 point, and the vertical line of P1 point and X axis, and the vertical line of P1 point and X axis. b The greater S is, the worse the retardation effect of the asphalt on the heavy metal elements in the fly ash is, and the higher the leaching concentration of the heavy metal elements is.

[0172] S is the total envelope area of the curve c S is the area of the figure enclosed by the connecting line of P1 point and P3 point, and the vertical line of P1 point and X axis, and the vertical line of P1 point and X axis. a S is the area of the figure enclosed by the connecting line of P1 point and P3 point, and the vertical line of P1 point and X axis, and the vertical line of P1 point and X axis. b S is the sum of the areas, when S c The greater S is, the worse the retardation effect of the asphalt on the heavy metal elements in the fly ash is, and the higher the leaching concentration of the heavy metal elements is.

[0173] It should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for preparing a test specimen for the heavy metal element retention performance of waste fly ash, characterized in that, It is prepared by the following steps: Step (1): Mix different amounts of waste fly ash material with asphalt material to obtain waste fly ash-asphalt mortar with various admixture amounts. At the same time, apply release agent to the inside and bottom of multiple sub-molds and the main mold. Step (2): Melt the fly ash-asphalt mortar with multiple admixtures and fill the corresponding molds, then cool it down. Step (3): After curing, the fly ash-asphalt mortar with different doping amounts is demolded to obtain multiple asphalt mortar components with different doping amounts. Step (4): Assemble multiple asphalt mortar components to obtain a composite block, and then place the composite block into the main mold; Step (5): Add molten asphalt to the main mold to fill the pores of the composite block to obtain asphalt precast specimens; Step (6): Heat the asphalt precast specimen and the main mold together until the asphalt surface temperature remains constant at the target temperature. The heat treatment is then complete. Step (7): Cool the asphalt precast specimen and the main mold, and finally take out the asphalt precast specimen to obtain the final test specimen; The mold includes one cylindrical mold, β annular molds and one cylindrical mold, where 2≤β≤10; The asphalt mortar component includes one cylindrical component corresponding to the cylindrical mold, β annular components corresponding to the annular mold, and one cylindrical component corresponding to the cylindrical mold. The assembly block is assembled by stacking multiple annular components in descending order of doping concentration, with cylindrical components fitted at the center of the stacked annular components and cylindrical components fitted at the outer periphery of the stacked annular components, thereby forming a columnar assembly block. The cylindrical component has the highest doping content; The cylindrical component has the lowest doping level; The doping amount of all the annular components is not the same, and the doping amount of all the annular components is less than the doping amount of the cylindrical component, but greater than the doping amount of the cylindrical component. In the annular subdivisions, there are at least two cylindrical subdivisions with the same doping amount.

2. The method for preparing test specimens for the heavy metal element retention performance of waste fly ash according to claim 1, characterized in that: The height of the annular component is defined as α, and the heights of the cylindrical component and the cylindrical component are both α×β, where 1cm≤α≤10cm. The outer diameter of the cylindrical component is equal to the inner diameter of the annular component; the outer diameter of the cylindrical component is equal to the outer diameter of the annular component.

3. The method for preparing test specimens for the heavy metal element retention performance of waste fly ash according to claim 2, characterized in that: In step (1), the amount of waste fly ash-asphalt mortar added is 0%-20%, and the mixing conditions are: mixing is carried out in a high-speed shear apparatus at a shear rate of 3000 rad / min and a shear time of 15 min. The cooling treatment is performed at -20℃±2℃ for 30-60 minutes. In step (6), when the asphalt material added in step (1) is base asphalt, the heating treatment is carried out to a target temperature of 110°C; when the asphalt material added in step (1) is modified asphalt, the heating treatment is carried out to a target temperature of 130°C.

4. The method for preparing test specimens for the heavy metal element retention performance of waste fly ash according to claim 3, characterized in that: The cylindrical component has a diameter of 2cm and a height of 12cm; The inner diameter of the annular component is 2cm, the outer diameter is 10cm, and the height is 2cm. The cylindrical component has an inner diameter of 10cm, an outer diameter of 12cm, and a height of 12cm. The cylindrical mold is a two-piece semi-cylindrical steel tube with a base and a circular clamp. The steel tube has an inner diameter of 2cm, an outer diameter of 2.5cm, and a height of 12.2cm. The circular clamp has an inner diameter of 2.5cm and an outer diameter of 3cm. The base has a diameter of 3cm, a thickness of 0.5cm, and a groove depth of 0.2cm. The circular die is a steel tube with a base and two layers of circular rings. The inner diameter of the large ring is 10cm, the outer diameter is 10.5cm, and the height is 2.2cm. The inner diameter of the small ring is 1.5cm, the outer diameter is 2cm, and the height is 2.2cm. The diameter of the base is 12cm, the thickness is 0.5cm, and the depth of the groove is 0.2cm. The cylindrical mold is a double-layered circular steel tube with a base. The inner diameter of the large ring is 12cm, the outer diameter is 13cm, and the height is 12.2cm. The inner diameter of the large ring is 9cm, the outer diameter is 10cm, and the height is 12.2cm. The diameter of the base is 14cm, the thickness is 0.5cm, and the depth of the groove is 0.2cm. The main mold is a steel cylindrical tube with a base. The tube has an outer diameter of 12.5cm, an inner diameter of 12cm, and a height of 12.2cm. The base has a diameter of 14cm and a height of 2cm. There is a positioning pin at the center of the base, and the positioning pin has a diameter of 1mm and a height of 5cm. In step (1), the doping amount of the waste fly ash-asphalt mortar is 15%, 13%, 10%, 7% and 0%, wherein the doping amount of the cylindrical component is 0%, the doping amount of the cylindrical component is 15%, the doping amount of the two annular components is 13%, the doping amount of the two annular components is 10%, and the doping amount of the two annular components is 7%.

5. An evaluation method for test specimens prepared by the test specimen preparation method for the heavy metal element blocking performance of waste fly ash as described in any one of claims 3-4, characterized in that: This includes unit mass testing of asphalt at different layers of the test specimen and heavy metal element solubility testing under different working conditions; In the heavy metal element solubility test under different working conditions, the solubility solution P1 under the upper immersion condition, the solubility solution P2 under the full immersion condition, and the solubility solution P3 under the lower immersion condition were filtered through a membrane filter and diluted 100 times. The differences in the solubility of heavy metal elements under different working conditions are expressed as the area S of the curve top envelope. a The indicators are evaluated as shown in equation (Ⅲ): S a =P2—0.5P1—0.5P3……Equation (Ⅲ); The leaching properties of heavy metal elements under different working conditions were measured using the lower envelope area S of the curve. b The indicators are used for evaluation, as shown in Equation (Ⅳ): S b =P1+P3……Equation (Ⅳ); The asphalt's inhibitory effect on the migration and leaching of heavy metal elements in waste fly ash under different working conditions was measured using the total envelope area S of the curve. c The indicators are used for evaluation, as shown in equation (V): S c =S a +S b =P2+0.5P1+0.5P3……Equation (V).

6. The evaluation method according to claim 5, characterized in that: The unit mass test of asphalt at different layers is carried out by the following steps: Step a1: Cut the test piece into β parts from top to bottom along the axial height direction, with the thickness of each layer being α, to obtain β cut pieces; Step a2: Weigh each of the β mass measuring containers to obtain M. 0-1 ... M 0-i ... M 0-β 2≤i≤β; Simultaneously, heat and melt β pieces respectively, then pour them into β corresponding mass measuring containers, making the liquid level higher than the edge of the mass measuring container, and the volume of the mass measuring container is smaller than the volume of the piece, and the volumes of all the mass measuring containers are equal; Step a2: Cool all the mass measuring containers and the internal cutting parts to room temperature. Use a scraper to smooth the asphalt surface along the edge of the mass measuring container. Weigh the mass measuring containers again to obtain M. 2-1 ... M 2-i ... M 2-β ; Step a3: Calculate the unit mass in β of the mass measuring containers according to formula (I), and then calculate the maximum difference M according to formula (II). 2-max When M 2-max The specimen preparation quality is qualified when the weight is ≤0.05g; M 2-i =M 1-i —M 0-i ...Formula (I); M 2-max =Max{M 2-i }—Min{M 2-i Equation (II) ...

7. The evaluation method according to claim 6, characterized in that: The heavy metal element solubility test under different working conditions includes upper immersion condition, lower immersion condition and full immersion condition; The above-ground immersion condition is carried out by the following steps: Step b1: Use a plastic sleeve that matches the diameter of the test piece, then put the upper part of the test piece over it so that the plastic sleeve contacts the test piece, with the contact height being 1cm. Then, use clamps to tighten the plastic sleeve in the overlapping area. Step b2: Seal the inside of the plastic sleeve that is in contact with the test piece using paraffin wax; Step b3: Fill the plastic sleeve with the leaching solution and allow the liquid to overflow. Then seal the plastic sleeve with plastic wrap and seal the top of the plastic sleeve with the cap. Keep the test piece and the plastic sleeve at a constant temperature of 60°C for 16-28 hours. Step b3: Take out the solution and define it as solution P1; The lower immersion condition is carried out by the following steps: Step c1: Use a plastic sleeve that matches the diameter of the test piece, then put the lower part of the test piece over it so that the plastic sleeve contacts the test piece, with the contact height being 1cm. Then, clamp the plastic sleeve in the overlapping area. Step c2: Use paraffin wax to seal the inside of the plastic sleeve that is in contact with the test piece; Step c3: Fill the plastic sleeve with the leaching solution and allow the liquid to overflow. Then seal the plastic sleeve with plastic wrap and seal the top of the plastic sleeve with the cap. Finally, invert the test piece and store the test piece and the plastic sleeve at a constant temperature of 60°C for 16-28 hours. Step c3: Take out the solution and define it as solution P3; All the aforementioned immersion conditions are carried out through the following steps: Step d1: Take a water immersion container with a volume larger than that of the test piece, and the diameter of the water immersion container is larger than that of the test piece. Fix the fixing pin in the water immersion container. Step d2: Insert the fixing pin along the central axis into the bottom center of the test piece, so that the bottom of the test piece is α away from the bottom surface of the immersion container; Step d3: Fill the immersion container with leaching solution so that the top surface of the test piece is lower than the height α of the leaching solution, and keep the test piece and the immersion container at a constant temperature of 60°C for 16-28 hours. Step d3: Take out the solution and define it as solution P2.

8. The evaluation method according to claim 7, characterized in that: The mass measuring container is a cylindrical container with an inner diameter of 55 mm and a depth of 35 mm. The plastic sleeve is a cylindrical container with a diameter of 12.1 cm and a height of 6 cm; The immersion container is a cylindrical container with a diameter of 16cm and a height of 16cm.

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