阅读说明：本技术 一种掺胶粉的沥青砂生产制备方法 (Production and preparation method of asphalt sand doped with rubber powder ) 是由 任园 陈修林 方肖立 张玉斌 鲍世辉 王春红 曹祝林 牛京涛 王祥彪 于 2021-09-06 设计创作，主要内容包括：本发明提供一种掺胶粉的沥青砂生产制备方法,采用尾矿砂、粒径0～3mm、粒径3～5mm两档集料合成级配,并以合成级配剩余空隙率控制其击实后密实状态,通过加入胶粉与沥青发生溶胀反应,沥青粘度有所增加,进而裹附集料的结构沥青比例上升,本发明以设计空隙率和级配合成剩余空隙率控制胶粉及沥青掺入量,避免混合料设计时完全依赖设计空隙,过渡追求低空隙率造成沥青含量过高,以掺胶粉沥青砂的最终沥青膜厚度为控制值,通过沥青膜及空隙率的变化理论计算胶粉和沥青掺量,从而制备出的沥青砂有更强应力吸收能力,其柔韧性、变形协调性、抗裂性等路用性能均较为优越,同时,掺入细粒度的尾矿砂,实现固体废弃物的再生使用。(The invention provides a method for preparing asphalt sand doped with rubber powder, which adopts tailing sand, aggregates with the grain diameter of 0-3 mm and the grain diameter of 3-5 mm to synthesize gradation, controls the compacted state of the aggregates after compaction according to the residual porosity of the synthesized gradation, increases the viscosity of asphalt by adding the rubber powder and asphalt to perform swelling reaction, further increases the proportion of the structural asphalt coated with the aggregates, controls the mixing amount of the rubber powder and the asphalt according to the designed porosity and the residual porosity of the gradation synthesis, avoids the situation that the design of a mixture completely depends on the designed clearance, excessively high asphalt content is caused by transitively pursuing low porosity, calculates the mixing amount of the rubber powder and the asphalt according to the change theory of the asphalt membrane and the porosity by taking the final asphalt membrane thickness of the asphalt sand doped with the rubber powder as a control value, and has higher stress absorption capacity, superior road performance such as flexibility, deformation coordination, crack resistance and the like, meanwhile, tailing sand with fine granularity is doped, so that the solid waste is recycled.)

1. A method for producing and preparing asphalt sand mixed with rubber powder is characterized by comprising the following steps: the method comprises the following steps:

(1) the rubber powder modified asphalt sand comprises: screening the aggregates and the tailing sand of each grade to determine the grading composition of the aggregates and the tailing sand of each grade;

(2) carrying out the grading design of the bituminous sand ore material according to the specified grading range, and determining the blending proportion of tailing sand, fine aggregate with the particle size of 0-3 mm and coarse aggregate with the particle size of 3-5 mm by taking 2.36mm, 0.6mm and 0.075mm as key sieve pores;

(3) blending the tailing sand, the fine aggregate with the particle size of 0-3 mm and the coarse aggregate with the particle size of 3-5 mm according to the proportion, calculating the theoretical density according to the blending proportion of the synthetic grading, compacting the aggregate by adopting a Marshall compaction method, calculating the compacted density of the synthetic grading, and calculating the residual gap of the synthetic grading according to the compacted density;

(4) filling the residual gaps with asphalt and rubber powder, performing swelling reaction on the rubber powder and the asphalt to cause the thickness change value of the front and back asphalt films, controlling the thickness of the asphalt film after the rubber powder reaction to be a certain value, and calculating the optimal mixing proportion of the rubber powder and the asphalt by combining the gap value of the mixture and the thickness change of the asphalt film;

(5) the mixing station mixes the asphalt sand mixed with the rubber powder, and the mixing process comprises the following steps: heating fine aggregates with the particle size of 0-3 mm and coarse aggregates with the particle size of 3-5 mm in a heating roller; adding the tailing sand and the rubber powder into the aggregate, and dry-mixing for 10-15 s in a mixing cylinder; and adding the asphalt into the stirring cylinder and uniformly stirring for 35-45 s.

2. The method for producing and preparing rubber-powder-doped tar sands as claimed in claim 1, wherein the blending ratio of the tar sand mineral aggregate is preliminarily calculated according to the following formula, then normalized, the gradation is synthesized according to the preliminarily calculated and normalized blending ratio and the raw material sieving result, if the gradation range is exceeded, the upper and lower limit ranges of the gradation requirement are revised:

in the formula: p_w-tailing sand blending; p_0～3Aggregate mixing ratio with particle size of 0-3 mm; p_3～5Aggregate mixing ratio with the particle size of 3-5 mm; d_w0.075-tailing sand passage rate 0.075 mm;

d_w0.6-passage rate of 0.6mm of tailings sand; d_w2.36-2.36 mm passage rate of tailings sand; d_x0.6-0-3 grade 0.6mm passing rate; d_x2.36A passing rate of 2.36mm for 0-3 grade materials; d_c2.36A 2.36mm passing rate of 3-5 grade materials; s_0.075Grading requires a pass rate of 0.075 mm; s_0.6-grading requires a passage rate of 0.6 mm; s_2.36Grading requires a 2.36mm throughput rate.

3. The method for preparing the asphalt sand doped with the rubber powder as shown in claim 1, which is characterized by comprising the following steps: the residual porosity of the composite grading is calculated according to the following formula:

in the formula: SVV-residual void fraction after compaction of synthetic grading; rho_s-composite grade compacted density;

ρ_g-synthetic grading theoretical maximum density.

4. The method for preparing the asphalt sand doped with the rubber powder as shown in claim 1, which is characterized by comprising the following steps: the optimal mixing proportion of the rubber powder and the asphalt is calculated according to the following formula:

u₁/u₂＝P_a/(P_a+P_j)

in the formula: VV-designed porosity of tar sand; rho_a-the pitch density; rho_j-glue powder density;

P_a-the amount of bitumen incorporation; p_jThe mixing amount of the rubber powder; u. of₁-thickness of asphalt film; u. of₂-controlling the thickness of the asphalt film added to the rubber powder.

5. The method for preparing the asphalt sand doped with the rubber powder as shown in claim 1, which is characterized by comprising the following steps: the thickness of the asphalt film is 8-11 um, and the thickness control value of the asphalt film is 12-16 um in the process of the prepared rubber powder-doped asphalt sand after the rubber powder and the asphalt are subjected to swelling reaction.

6. The method for preparing the rubber-doped asphalt sand as claimed in claim 1, wherein the method comprises the following steps: the maximum grain size of the tailing sand is 1.18mm, wherein the passing rate of 0.075mm is not less than 75%.

7. The method for preparing the rubber-doped asphalt sand as claimed in claim 1, wherein the method comprises the following steps: the porosity of the bituminous sand is 1.5-3.0%, and the residual porosity of the synthetic grading is 9-13%.

Technical Field

The invention relates to the technical field of road engineering, in particular to a method for producing and preparing asphalt sand doped with rubber powder.

Background

Rainwater falls to the road surface, if permeate the road surface structural layer inside, under the action of hydrodynamic pressure, can cause the layer to peel off, appear such as early diseases such as pot hole, crack, falling grain, to structures such as bridge, culvert, the road surface oozes inside the beam slab under water, can corrode the reinforcing bar, influences bridge structure security, and its fruit is fairly serious afterwards. At present, pavement structure adopts the surface course to be flexible bituminous mixture, basic unit for semi-rigid, rigid material more, and modulus and rigidity are different between surface course, the basic unit, receives complex environment and load effect, and surface course, basic unit atress warp, and the harmony is relatively poor between the two, and diseases such as delaminating, fracture appear very easily, and road surface uses the durability to stand great examination.

The asphalt sand is an asphalt mixture with the grain diameter smaller than 5mm and the oilstone ratio higher, the void ratio of the asphalt sand is about 2-3%, the communication void ratio is almost 0, the underwater infiltration channel effect is isolated in an asphalt layer, the asphalt content in the asphalt sand is up to more than 6%, the asphalt sand is good in flexibility, strong in deformation tracing, and has certain self-repairing capacity, the void ratio of the asphalt sand is small, the bonding area with the lower bearing layer interface is large, the oilstone ratio is high, the bonding performance is strong, the asphalt sand can form high-efficiency bonding with the lower bearing layer interface, the asphalt sand has better advantages in the aspects of water resistance, crack resistance and bonding, and the service durability of the pavement can be improved. During conventional bituminous sand design, the porosity after aggregate synthesis is not considered in the synthetic grading process, and when the later-stage mix proportion design sets the oilstone ratio, in order to ensure that the porosity is lower, and too much asphalt is added, the residual free asphalt content after the asphalt is wrapped by the aggregate is more, and the segregation is easy to occur. Therefore, it is necessary to effectively control the void ratio in the grading design and the oilstone ratio determination process, reduce the amount of free asphalt and increase the thickness of the structural asphalt film, so as to improve the pavement performance of the prepared asphalt sand.

Disclosure of Invention

The invention aims at the defects in the process of producing and preparing the bituminous sand, and aims to provide a method for producing and preparing the bituminous sand doped with the rubber powder.

The technical problem to be solved by the invention is realized by adopting the following technical scheme:

a method for producing and preparing asphalt sand doped with rubber powder comprises the following steps:

(1) the rubber powder modified asphalt sand comprises: screening the aggregates and the tailing sand of each grade to determine the grading composition of the aggregates and the tailing sand of each grade;

(2) carrying out the grading design of the bituminous sand ore material according to the specified grading range, and determining the blending proportion of tailing sand, fine aggregate with the particle size of 0-3 mm and coarse aggregate with the particle size of 3-5 mm by taking 2.36mm, 0.6mm and 0.075mm as key sieve pores;

(3) blending the tailing sand, the fine aggregate with the particle size of 0-3 mm and the coarse aggregate with the particle size of 3-5 mm according to the proportion, calculating the theoretical density according to the blending proportion of the synthetic grading, compacting the aggregate by adopting a Marshall compaction method, calculating the compacted density of the synthetic grading, and calculating the residual gap of the synthetic grading according to the compacted density;

(4) filling the residual gaps with asphalt and rubber powder, performing swelling reaction on the rubber powder and the asphalt to cause the thickness change value of the front and back asphalt films, controlling the thickness of the asphalt film after the rubber powder reaction to be a certain value, and calculating the optimal mixing proportion of the rubber powder and the asphalt by combining the gap value of the mixture and the thickness change of the asphalt film;

(5) the mixing station mixes the asphalt sand mixed with the rubber powder, and the mixing process comprises the following steps: heating fine aggregates with the particle size of 0-3 mm and coarse aggregates with the particle size of 3-5 mm in a heating roller; adding the tailing sand and the rubber powder into the aggregate, and dry-mixing for 10-15 s in a mixing cylinder; and adding the asphalt into the stirring cylinder and uniformly stirring for 35-45 s.

The blending proportion is preliminarily calculated according to the following formula, then normalization processing is carried out, the gradation is synthesized according to the blending proportion of the preliminarily calculated normalized thickness and the screening result of the raw materials, and if the blending proportion exceeds the gradation range, the upper limit range and the lower limit range of the gradation requirement are revised

In the formula: p_w-tailing sand blending; p_0～3Aggregate mixing ratio with particle size of 0-3 mm;

P_3～5aggregate mixing ratio with the particle size of 3-5 mm; d_w0.075-tailing sand passage rate 0.075 mm;

d_w0.6-passage rate of 0.6mm of tailings sand; d_w2.36-2.36 mm passage rate of tailings sand;

d_x0.6-0-3 grade 0.6mm passing rate; d_x2.362.36mm passing rate of-0-3 grade material；d_c2.36A 2.36mm passing rate of 3-5 grade materials; s_0.075Grading requires a pass rate of 0.075 mm;

s_0.6-grading requires a passage rate of 0.6 mm; s_2.36-grading requires a 2.36mm throughput rate;

the residual porosity of the composite grading is calculated according to the following formula:

in the formula: SVV-residual void fraction after compaction of synthetic grading; rho_s-composite grade compacted density;

ρ_g-synthetic grading theoretical maximum density;

determining the optimal mixing proportion of the rubber powder and the asphalt of the asphalt sand mixed with the rubber powder according to the following formula:

u₁/u₂＝P_a/(P_a+P_j)

in the formula: VV-designed porosity of tar sand; rho_a-the pitch density; rho_j-glue powder density;

P_a-the amount of bitumen incorporation; p_jThe mixing amount of the rubber powder; u. of₁-thickness of asphalt film; u. of₂-the thickness of the crumb rubber asphalt film;

in the production and preparation process of the asphalt sand doped with the rubber powder, the thickness of the asphalt film is 8-11 um, and after the rubber powder and the asphalt are subjected to swelling reaction, the thickness control value of the asphalt film is 12-16 um.

The designed porosity in the preparation process of the asphalt sand doped with rubber powder is controlled to be 1.5-3.0%, and the residual porosity of the synthetic grading is controlled to be 9-13%.

The maximum grain size of the tailing sand selected in the production and preparation process of the asphalt sand doped with rubber powder is 1.18mm, wherein the passing rate of 0.075mm is not less than 75%.

The invention has the beneficial effects that:

according to the invention, the rubber powder is doped into the asphalt sand, the rubber powder is added to perform a swelling reaction with the asphalt, the thickness of the asphalt film is increased, the proportion of the structural asphalt in the asphalt wrapped by the aggregates is greatly increased, the aggregates are bonded more firmly, the asphalt sand has stronger stress absorption capacity, and the road performances such as flexibility, deformation coordination, crack resistance and the like are improved.

The invention provides a method for producing and preparing asphalt sand doped with rubber powder, which increases the residual porosity of synthetic gradation as a control value, ensures that aggregates form a better compact state in the preparation process of the asphalt sand, and avoids reducing the porosity by adding an oilstone ratio, thereby reducing the generation of segregation and ensuring the uniformity of an asphalt sand mixture.

The invention provides a method for producing and preparing asphalt sand doped with rubber powder, which establishes the relationship between the mixing amount of asphalt and rubber powder of a mixture and the change of gaps according to the change of an asphalt film after the rubber powder is added from the aspect of asphalt film-forming performance, and can dynamically adjust the adding amount of the asphalt and the rubber powder in real time according to the change of the gaps in the production process of the asphalt sand so as to effectively control the production cost and the quality of the mixture.

The filler provided by the invention adopts the tailing sand with fine granularity, and the industrial waste is recycled, so that the resource utilization of the waste is realized, the resource is saved, and the filler is efficient and environment-friendly.

Detailed Description

The present invention will be further described with reference to specific embodiments for the purpose of facilitating an understanding of technical means, characteristics of creation, objectives and functions realized by the present invention, but the following embodiments are only preferred embodiments of the present invention, and are not intended to be exhaustive. Based on the embodiments in the implementation, other embodiments obtained by those skilled in the art without any creative efforts belong to the protection scope of the present invention.

The production and preparation method of the asphalt sand doped with the rubber powder comprises the following steps of screening the tailing sand by 0-3 mm and 3-5 mm grades, wherein the results are as follows:

TABLE 1 raw material screening results

TABLE 2 raw material Density

Material	3-5 grade aggregate	0-3 grade aggregate	Tailing sand	Asphalt	Rubber powder
						Density (kg/m)3)	2.702	2.654	2.671	1.02	1.10

Grading synthesis is carried out, the materials are taken as key sieve pores for control according to 0.075mm, 0.6mm and 2.36mm, the values of the key sieve pores are considered according to the intermediate values of the upper limit and the lower limit of the grading, namely the passing rates of 0.075mm, 0.6mm and 2.36mm are respectively 10%, 31% and 72%, and the blending proportion is calculated according to the following formula:

the results of the calculation were normalized to obtain blending ratios of 0.075mm, 0.6mm, and 2.36mm of 12.1%, 50%, and 37.9%. The grading synthesis was carried out as shown in the following table:

TABLE 3 bituminous sand grading composition results

According to the gradation synthesis result, the theoretical synthesis density is rho_g＝2.674kg/m³Compacting the single surface of the aggregate of synthetic grade 100 times, and measuring compacted density rho_s＝2.356kg/m³Residual porosity after aggregate synthesis:

the designed void ratio is 2.5 percent, the thickness of the asphalt film is 9.6um, the thickness of the asphalt film after rubber powder reaction is controlled according to 13.8um,

9.6/13.8＝P_a/(P_a+P_j)

the calculation results are that: asphalt-to-stone ratio P_a6.8 percent of the rubber powder mixing amount P_jThe content was found to be 3.0%.

Preparing Marshall test pieces with the mixture oil-stone ratios of 6.5 percent, 6.8 percent and 7.1 percent under the following conditions:

adding the aggregate into an oven and heating to 190-210 ℃;

the heating temperature of the asphalt is 160-165 ℃;

dry-mixing the rubber powder, the tailing sand and the aggregate in a mixing cylinder for 15s, adding the asphalt into the mixing cylinder for uniform mixing, and ensuring that the mixing temperature is 175-;

taking the mixture obtained in the above step out of the pot at the temperature of 175-180 ℃, and forming at the temperature of 170-175 ℃.

The results of the Marshall test are shown in Table 3.

TABLE 4 Marshall test results for rubber-powder-doped tar sands

When the void ratio of the mixture is 2.5 percent, the optimal oilstone ratio is 6.76 percent, the pavement performance is verified, and the performance results of the sand asphalt mixture doped with the rubber powder are shown in Table 4.

TABLE 5 performance of rubber-powder-doped asphalt sand road

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the preferred embodiments of the present invention are described in the above embodiments and the description, and are not intended to limit the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.