CN113087487A

CN113087487A - Construction process for red mud coal gangue aggregate pavement base course stabilized by carbide slag and coal ash

Info

Publication number: CN113087487A
Application number: CN202110366795.8A
Authority: CN
Inventors: 王晓丰; 赵辉; 白哲; 王壹帆; 王健; 曹金奎; 王海有; 薛秋香
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-04-06
Filing date: 2021-04-06
Publication date: 2021-07-09

Abstract

The invention provides a construction process of a red mud coal gangue aggregate pavement base course stabilized by carbide slag and fly ash, wherein the pavement base course comprises the following materials in parts by weight: 5-15 parts of carbide slag, 5-15 parts of fly ash, 5-15 parts of red mud, 60-70 parts of coal gangue and 7-14 parts of water. Before construction, designing the mixture ratio, converting the adopted design mixture ratio into a construction mixture ratio, and mixing the coal gangue, the carbide slag, the fly ash, the red mud and water into a construction primary mixed material by a batching machine according to the construction mixture ratio; and crushing/mixing the construction primary mixed materials, discharging to obtain the mixture of the acetylene sludge and coal ash stabilized red mud and coal gangue aggregate pavement base, and then transporting, paving, rolling and maintaining the mixture of the base to obtain the acetylene sludge and coal ash stabilized red mud and coal gangue aggregate pavement base. The early strength and the long-term strength of the pavement base are both obviously improved; the invention can use a large amount of industrial waste, simplifies the construction process, has simple matched mechanical equipment, is easy to master the construction technology and is convenient to popularize and apply.

Description

Construction process for red mud coal gangue aggregate pavement base course stabilized by carbide slag and coal ash

Technical Field

The invention relates to the technical field of road construction, in particular to a construction process for a red mud coal gangue aggregate pavement base course stabilized by carbide slag and coal ash.

Background

With the rapid development of economy in China, road construction is also developed at a high speed for decades and will continue to be developed at a high speed. The road surface structure of roads in China is mostly a semi-rigid base asphalt concrete road surface, a large amount of broken stones, cement and lime are consumed for building the semi-rigid base, certain damage is caused to the ecological environment, pollution is caused, and meanwhile, the price is high. On the other hand, the rapid development of the industry discharges a large amount of industrial waste residues, such as carbide slag, fly ash, red mud, coal gangue and the like, and how to build a semi-rigid pavement base layer by using the industrial waste residues is a problem which needs to be solved urgently.

The carbide slag is industrial waste slag discharged in large quantity when acetylene is prepared by hydrolyzing calcium carbide, and the main active component of the carbide slag is calcium hydroxide. The coal gangue is solid waste discharged in the coal mining process and the coal washing process, is a black grey rock which has lower carbon content and is harder than coal and is associated with a coal bed in the coal forming process, comprises tunneling gangue in the tunneling process, gangue mined from a top plate, a bottom plate and an interlayer in the mining process and washing gangue picked in the coal washing process, and mainly comprises Al₂O₃、SiO₂And in addition, Fe in different quantities₂O₃、CaO、MgO、Na₂O、K₂O、P₂O₅、SO₃And trace rare elements (gallium, vanadium, titanium, cobalt)The annual emission of China has exceeded 7 hundred million tons in the past. The fly ash is the main solid waste discharged by coal-fired power plants, and the main oxide composition of the fly ash of the heat-engine plants in China is SiO₂、Al₂O₃、FeO、Fe₂O₃、CaO、TiO₂Along with the development of the power industry, the emission amount of fly ash of coal-fired power plants is increased year by year, and the fly ash becomes one of industrial waste residues with larger discharge amount in China. The red mud is polluting waste residue discharged when alumina is extracted in the aluminum industry, the waste residue discharged after alumina is extracted by adopting a Bayer process is called Bayer process red mud, the stock quantity of the red mud in China currently exceeds 4 hundred million tons, the red mud consists of particles with the diameter of 0.088-0.25 mm, the main minerals of the red mud are aragonite and calcite, the content of the aragonite and the calcite is 60-65%, next, the red mud is opal, gibbsite and goethite, the content of the red mud is titanium ore, siderite, natural alkali, water glass, sodium aluminate and caustic soda is the least, the discharge quantity of the red mud in China currently exceeds 600 million tons, the treatment and the comprehensive utilization of the red mud become a big problem worldwide, the red mud is mainly stacked at present, besides occupying a large amount of soil, the alkaline and underground water pollution are easily caused by the fact that chemical components in the red mud infiltrate into the land, particularly, the red mud contains a large amount of strong alkaline chemical substances, the pH value is still 11.25-11, the extremely high pH value determines the strong corrosivity of the red mud to biological, metal and siliceous materials, and the direct discharge of the red mud effluent is overproof.

The acetylene sludge and coal ash stabilized red mud and coal gangue aggregate pavement base course can consume a large amount of acetylene sludge, coal ash, red mud and coal gangue, is a strategy of high efficiency and low consumption, is optimal for solving serious pollution, and simultaneously solves the problems of shortage and high price of road building materials.

At present, the mixture of the acetylene sludge and the fly ash for stabilizing the coal gangue aggregate pavement base is not uniformly mixed, and the early strength and the long-term strength are low, so that the popularization and the application are not facilitated.

Disclosure of Invention

The invention aims to provide a construction process for a pavement base course with stabilized red mud and coal gangue aggregates by carbide slag and fly ash, which solves the problems of uneven mixing of pavement base course mixture and low early strength and long-term strength.

In order to achieve the purpose, the invention adopts the technical scheme that:

the red mud coal gangue aggregate pavement base course stabilized by the carbide slag and the fly ash comprises the following materials in parts by weight: 5-15 parts of carbide slag, 5-15 parts of fly ash, 5-15 parts of red mud, 60-70 parts of coal gangue and 7-14 parts of water. The maximum usage amount of the coal gangue is 70 parts, and the pavement base layer structure is guaranteed to be in a suspension compact type. Research shows that for a suspended compact pavement base course structure, the change of aggregate gradation has no regular influence on the strength of the suspended compact pavement base course structure; within the specified range, i.e. + -. 2%, the change in the amount of aggregate had no regular effect on its strength.

Furthermore, the quality of the carbide slag, the fly ash, the coal gangue and the water meets the regulation of JTG/T F20-2015. The coal gangue exists in two states, namely the state before crushing is still called coal gangue, and the state after crushing is called coal gangue aggregate, and the quality of the coal gangue is unchanged after the coal gangue is converted into the coal gangue aggregate. Thus, the mass ratio is constant.

Further, the red mud is Bayer process red mud, and the water content of the red mud is 20wt% at most.

Further, the water content of the carbide slag is 20wt% at the maximum.

A construction process for stabilizing a red mud coal gangue aggregate pavement base course by using carbide slag and fly ash comprises the following steps:

step 1, mixing carbide slag, fly ash, red mud, coal gangue and water according to a construction quality mixing ratio to obtain a construction primary mixed material;

step 2, crushing/mixing the construction primary mixed materials, and discharging to obtain a mixture of the calcium carbide slag, the coal ash and the stabilized red mud, coal gangue and aggregate pavement base, which is called a base mixture for short;

step 3, transporting the base layer mixture

According to the requirements of (JTG/T F20-2015) detail rules for highway pavement base construction technology;

step 4, paving the base layer mixture

step 5, rolling of base layer mixture

step 6, maintenance

According to the requirements of JTG/T F20-2015, the technical rules for constructing the highway pavement base course.

Further, the maximum particle size of the base layer mixture is 31.5 mm.

Further, the design steps of the construction quality mixing ratio adopted in the step 1 are as follows:

1) determining the mass mixing ratio of the three groups of different carbide slag, the fly ash, the red mud and the coal gangue to be 10-15:5-10: 60-70;

2) mixing each group of dried materials obtained in the step 1) according to the mass mixing ratio to obtain a mixture of carbide slag, fly ash, red mud and coal gangue, wherein the mixture is referred to as a test primary mixture;

3) respectively crushing/mixing each group of test primary mixed materials, controlling the maximum particle size to be 31.5mm, and preparing a carbide slag, coal ash, red mud and coal gangue aggregate mixture, namely a crushed material of the test primary mixed materials, which is called as test primary mixed crushed materials for short;

4) taking each group of test primary mixed crushed materials respectively, and carrying out compaction test according to (T0804-;

5) mixing the initial mixed broken material and water respectively according to the ratio obtained in the step 4), and then testing each group according to (T0843-;

6) selecting a group of 7d unconfined compressive strengths of more than or equal to 0.8MPa as the adopted design mass mixing ratio, namely the design mixing ratio for short.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention achieves the purpose of uniformly mixing the mixture of the pavement base without lump carbide slag, solves the problem of non-uniform mixing in the prior art, can ensure the quality, obviously improves the early strength and the long-term strength of the pavement base, and creates conditions for large-scale popularization and application. The natural dehydration method is stacked to the present overwhelming majority of adoption of carbide slag, and the inside carbide slag water content of heap is big, is the bulk that has certain viscosity, and the surperficial carbide slag calcification of heap is the cubic that has certain intensity, and the long red mud of depositing time also can agglomerate in addition, and road surface basic unit mixture mixer only mixes the function, does not have crushing function, can not mix the massive carbide slag of group and red mud completely evenly, consequently leads to road surface basic unit intensity to reduce. Under the prior art conditions, no matter a mix proportion design test or a construction site mixture taking test, the strength of a pavement base layer mixture test piece is often less than 0.5MPa, according to the standard specification, the former shows that the mixture can not be used for building a pavement base layer, and the latter shows that the pavement base layer has unqualified strength; the invention firstly mixes the fly ash, the carbide slag, the red mud, the coal gangue and the water, and then crushes/mixes the mixture by a crusher, the coal gangue not only has a crushing function, but also has strong mixing capability, when the coal gangue is crushed into aggregates with different particle sizes, the blocky carbide slag with certain strength, the blocky carbide slag with certain viscosity and the caked red mud are all completely crushed into fine powder, the fine powder is fully mixed with other materials, the uniformity of the mixture of the pavement base course is ensured, and the strength of the pavement base course is further ensured, as shown in the following examples, the strength of a test piece of the mixture of the pavement base course is not lower than 3.5 MPa.

2. The pavement base layer can use a large amount of industrial waste, and has obvious environmental protection benefits, economic benefits and social benefits.

3. Compared with the prior art which relates to the pretreatment of various coal gangues and needs to be matched with aggregate in advance, the invention simplifies the construction process of the pavement base, simplifies the mechanical equipment matched with the process, improves the efficiency, reduces the cost, is easy to master the construction technology and is convenient to popularize and apply.

Drawings

FIG. 1 is a flow chart of the construction process of the pavement base of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Example 1

The red mud coal gangue aggregate pavement base course stabilized by the carbide slag and the fly ash comprises the following materials in parts by weight: 5-15 parts of carbide slag, 5-15 parts of fly ash, 5-15 parts of red mud, 60-70 parts of coal gangue and 7-14 parts of water.

The construction process of the pavement base layer is as shown in fig. 1, and the concrete method is as follows:

firstly, before construction, the mass mix proportion design is carried out, and specifically:

1) three groups of mass mixture ratios are selected, namely the ratios of the three groups of carbide slag, the fly ash, the red mud and the coal gangue. In this embodiment, the first group of mass mixing ratios: carbide slag, fly ash, red mud and coal gangue are = 10: 70; the second group of mass mixing ratios: carbide slag, fly ash, red mud and coal gangue = 12: 15: 5: 68; the third group comprises the following components in percentage by mass: carbide slag, fly ash, red mud and coal gangue = 15: 10: 65.

2) Taking the dried materials, mixing each group of the dried materials according to the mass mixing ratio to form a mixture of the carbide slag, the fly ash, the red mud and the coal gangue, wherein the mixture is referred to as a test initial mixture.

For example, when 100kg of test primary mixed material is prepared, 10kg of carbide slag, 10kg of fly ash, 10kg of red mud and 70kg of coal gangue are needed in the first group; the second group needs 12kg of carbide slag, 15kg of fly ash, 5kg of red mud and 68kg of coal gangue; the third group needs 15kg of carbide slag, 10kg of fly ash, 10kg of red mud and 65kg of coal gangue.

3) And (3) respectively putting each group of test primary mixed materials into a crusher for crushing/mixing, controlling the maximum particle size to be 31.5mm, and preparing the mixture of the carbide slag, the coal ash, the red mud and the coal gangue aggregates, namely the crushed materials of the test primary mixed materials, wherein the materials are called test primary mixed crushed materials. In the process of converting the test initial mixed material into the test initial mixed broken material, the coal gangue is changed into coal gangue aggregate.

4) Taking each group of the test initial mixed crushed materials in the step 3) respectively, and performing compaction tests according to (T0804-: 1.852g/cm³、1.761g/cm³And 1.783g/cm³The optimum water content is: 10.00 percent, 11.15 percent and 10.08 percent, thus obtaining three groups of mass mixing ratios, namely the ratio of the carbide slag to the fly ash to the red mud to the coal gangue aggregate to the water is respectively about: 9.000: 63.000: 10.000, 10.662: 13.328: 4.443: 60.418: 11.15 and 13.488: 8.992: 8.992: 58.448: 10.080.

Taking the first group as an example, the calculation method of the ratio of the carbide slag, the fly ash, the red mud, the coal gangue aggregate and the water comprises the following steps:

the optimum water content is 10.00%, then 100kg of the mixture of carbide slag, fly ash, red mud, coal gangue aggregate and water, the weight of water is 100kg × 10.00% and 10kg, the weight of carbide slag + fly ash + red mud + coal gangue aggregate + 100 kg-10 kg-90 kg, the weight of carbide slag: fly ash: red mud: coal gangue aggregate is 10: 70, then the weight of carbide slag-fly ash-red mud-10 ÷ (10 + 70) × 90 kg-9 kg, the weight of coal gangue aggregate-70 ÷ (10 + 70) × 90 kg-63 kg.

The same method can calculate the ratio of the second group of carbide slag, the fly ash, the red mud, the coal gangue aggregate and the water.

The ratio of the carbide slag, the fly ash, the red mud, the coal gangue aggregate and the water is converted into the ratio of (the carbide slag, the fly ash, the red mud and the coal gangue aggregate) to the water, namely the ratio of the test primary mixed crushed material to the water, so that the ratios of the three groups are respectively 90: 10, 88.85: 11.15 and 89.92: 10.08.

5) Mixing three groups of test initial mixed crushed materials and water according to the ratio of the test initial mixed crushed materials to the water obtained in the step 4), and then respectively testing each group according to (T0843-.

6) The first group is selected as the design mass mixing ratio, which is called the design mixing ratio for short, namely, the carbide slag, the fly ash, the red mud, the coal gangue and the water are = 9.000: 63.000: 10.000.

7) Converting the adopted design quality mixing ratio into the construction quality mixing ratio

Tests show that the water contents of the carbide slag, the fly ash and the red mud are all 10 percent, and the water content of the coal gangue is 3 percent. Converting the design mixing ratio of carbide slag, fly ash, red mud, coal gangue and water = 9.000: 63.000: 10.000 into a construction quality mixing ratio which is referred to as a construction mixing ratio for short, and calculating the result: carbide slag, fly ash, red mud, coal gangue and water are respectively 10.000: 64.949: 5.052.

Secondly, during construction, the concrete construction process is as follows:

1) according to the construction mixing proportion, coal gangue, carbide slag, fly ash, red mud and water are mixed by a batching machine, and the material is called as a construction primary mixed material;

for example, 10000kg of carbide slag, 10000kg of fly ash, 10000kg of red mud, 64949kg of coal gangue and 5052kg of water are mixed together according to the construction mixing ratio of carbide slag, fly ash, red mud, coal gangue and water = 10.000: 64.949: 5.052 to obtain 100001kg of construction primary mixed material;

2) adding the construction primary mixed material into a crusher for crushing/mixing, and discharging to obtain a mixture of the acetylene sludge, the coal ash and the stabilized red mud, coal gangue and the pavement base, which is called a base mixture for short; in the process of converting the construction primary mixed material into the base mixed material, the coal gangue is changed into coal gangue aggregate;

the crusher adopts impact crushing, the maximum grain size of the crusher is controlled by two measures, firstly, the gap between the plate hammer and the impact plate is adjusted to be 31.5mm at most, and the maximum grain size of more than 99 percent of discharged materials is 31.5 mm; secondly, the discharged materials pass through a sieve with the mesh size of 31.5mm multiplied by 31.5mm, and the granules with the grain size of less than 1 percent and the grain size of more than 31.5mm return to the impact crusher through a material returning system to be crushed again.

3) Transport of base mix

4) spreading of base layer mixture

5) rolling of base mix

6) and maintaining

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The red mud coal gangue aggregate pavement base course stabilized by the carbide slag and the fly ash is characterized by comprising the following materials in parts by weight: 5-15 parts of carbide slag, 5-15 parts of fly ash, 5-15 parts of red mud, 60-70 parts of coal gangue and 7-14 parts of water.

2. The red mud coal gangue aggregate pavement base course stabilized by carbide slag and fly ash of claim 1, wherein the quality of the carbide slag, fly ash, coal gangue and water conforms to the specification of JTG/T F20-2015 highway pavement base course construction technical rules.

3. The carbide slag/fly ash stabilized red mud/coal gangue aggregate pavement base as claimed in claim 1, wherein the red mud is bayer process red mud having a water content of at most 20 wt%.

4. The red mud coal gangue aggregate pavement base course stabilized by carbide slag and fly ash according to claim 1, wherein the water content of the carbide slag is at most 20 wt%.

5. A construction process for stabilizing a red mud coal gangue aggregate pavement base course by using carbide slag and fly ash comprises the following steps:

step 1, selecting the adopted design mass mixing ratio;

step 2, converting the design mass mixing ratio adopted in the step 1 into a construction mass mixing ratio;

step 3, mixing the materials according to the construction quality mixing ratio to obtain a construction primary mixed material;

step 4, crushing/mixing the construction primary mixed material to obtain a base layer mixed material;

step 5, transporting the base layer mixture

According to the requirements of the detailed rules of JTG/T F20-2015 highway pavement base construction technology;

step 6, paving the base layer mixture

step 7, rolling of the base layer mixture

step 8, maintenance

According to the detailed requirements of JTG/T F20-2015 highway pavement base course construction technology.

6. The construction process for the pavement base course made of the red mud coal gangue aggregates stabilized by the carbide slag and the fly ash according to claim 5, wherein the maximum particle size of the base course mixture is 31.5 mm.

7. The construction process for stabilizing the red mud coal gangue aggregate pavement base course by the carbide slag and the fly ash according to claim 5, wherein the step 1 adopts the following steps in design mass mixture ratio:

1) determining the mass mixing ratio of the three groups of different carbide slag, the fly ash, the red mud and the coal gangue to be 10-15:10-15:5-10: 60-70;

2) mixing each group of dried materials obtained in the step 1) according to the mass mixing ratio to obtain a test initial mixed material;

3) respectively crushing/mixing each group of test primary mixed materials, and controlling the maximum particle size to be 31.5mm to obtain test primary mixed crushed materials;

4) taking each group of test primary mixed crushed materials respectively, and performing compaction test according to a compaction test method of an inorganic binder stabilizing material of T0804-;

5) mixing the initial mixed broken material and water respectively according to the mass ratio of each group obtained in the step 4), and then testing each group according to a T0843-;

6) selecting a group of 7d unconfined compressive strengths of more than or equal to 0.8MPa as the adopted design mass mixing ratio.