A pavement base material, its preparation method and application

Abstract

The present application relates to solid waste resource utilization technical field, disclose a kind of road base material, including the following components by weight parts: harmless barium residue 80-95 parts, solid waste-based cementing material 5-20 parts and external addition water 10-15 parts, the preparation method of road base material includes the following steps: barium residue, desulfurization gypsum and water are mixed uniformly, after dampening material, drying, screening, obtain harmless barium residue;The harmless barium residue, solid waste-based cementing material and water are mixed uniformly, to obtain road base material.The road base material of the present application, stable cementing material is solid waste-based cementing material, and the only stable material is harmless barium residue, realizes the resource utilization of multiple industrial waste residue, realizes the large-scale utilization of barium residue, improves the resource utilization rate of barium residue, relieves the tension of road engineering sandstone material, reduces the amount of cement, and the preparation process is simple, and the applicability is wide, with significant economic and environmental benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste resource utilization, and particularly relates to a road base material and a preparation method and application thereof. BACKGROUND

[0002] Barium sulfate is an important chemical substance obtained from barite, and is mainly produced by a carbonization reduction method. A large amount of barium residue is generated in the production process of barium sulfate. The pollution coefficient of the barium residue in the carbonization reduction process is about 0.8, that is, 0.8 to 1 ton of barium residue is generated for every 1 ton of barium salt produced. At present, the annual emission amount of barium residue in China exceeds 1 million tons, and the cumulative total storage amount has exceeded 10 million tons.

[0003] The barium residue mainly contains acid-soluble barium and water-soluble barium, has a high barium ion content, is toxic, belongs to HW47 hazardous waste, and is long-term stacking. The barium residue not only occupies a large amount of land, but also pollutes the environment. In particular, the barium residue is easy to cause a self-ignition reaction to release toxic gases under high temperature, and generates a large amount of yellow wastewater containing sulfides after rainwater penetration, which flows into surface water and underground water, pollutes the water body, and has a toxic effect on the soil due to the barium sulfate and acid-soluble barium in the waste residue. The existing technology for the comprehensive utilization of barium residue is mainly concentrated in the fields of building materials and chemical products. However, the current technical process is complex, and the actual consumption amount of the barium residue is limited.

[0004] Therefore, how to provide a barium residue resource utilization method with simple technology and large consumption amount is a problem to be solved by those skilled in the art. SUMMARY

[0005] In view of this, the present application provides a road base material to solve the problems of the existing barium residue resource utilization method with complex technical process and limited actual consumption amount of the barium residue.

[0006] In order to solve the above technical problems, the present application adopts the following technical solutions:

[0007] On one hand, the present application provides a road base material, which comprises the following components in parts by weight: harmless barium residue 80-95 parts, solid waste-based cementitious material 5-20 parts, and external water 10-15 parts.

[0008] Preferably, the solid waste-based cementitious material comprises the following components in parts by weight: slag 60-70 parts, steel slag 20-30 parts, and desulfurization gypsum 10-20 parts.

[0009] Preferably, the specific surface area of the solid waste-based cementitious material is 450-500 m 2 / kg.

[0010] Preferably, the harmless barium residue comprises the following components in parts by weight: barium residue 70-90 parts and desulfurization gypsum 10-30 parts.

[0011] Preferably, the particle size of the harmless barium residue is ≤4.75 mm; further preferably, the particle size of the harmless barium residue is 0.075-2.36 mm.

[0012] Preferably, the pH is 6-9.

[0013] Preferably, the toxic leaching concentration of barium ions in the harmless barium residue is <10 mg / L.

[0014] Preferably, the barium residue is a solid waste discharged in a barium salt chemical process, and the desulfurization gypsum is a solid waste produced in a desulfurization workshop.

[0015] In another aspect, the present application also provides a preparation method of the pavement base material according to any one of the above, comprising the following steps:

[0016] (1) uniformly mixing the barium residue, the desulfurization gypsum and water, and after steaming, drying and sieving, obtaining the harmless barium residue;

[0017] (2) uniformly mixing the harmless barium residue, the solid waste-based cementitious material and water, to obtain the pavement base material.

[0018] Preferably, the steaming time is 20-28 h.

[0019] Preferably, the drying temperature is 50-60℃, and the drying is performed until the moisture content is less than 2%.

[0020] In addition, the present application also provides an application of the pavement base material according to any one of the above or the pavement base material prepared by the method according to any one of the above in a pavement material.

[0021] The present application provides a pavement base material and a preparation method thereof, and has the following beneficial effects compared with the prior art:

[0022] In the pavement base material provided by the present application, the only stabilizing material is barium residue, which realizes large-scale utilization of barium residue, improves the resource utilization rate of barium residue, and effectively alleviates the shortage of road engineering sand and gravel; the solid waste-based cementitious material is used to replace cement as a stabilizing material, which reduces the amount of cement used in road engineering; the solid waste-based cementitious material has good hydraulic properties and is a new type of cementitious material, which can completely replace cement to produce concrete of various grades and types; the production cost of the solid waste-based cementitious material is about 50% of that of cement, which makes it have obvious advantages in economy; in addition, the use of the solid waste-based cementitious material can save material cost by more than 10%, and each ton of solid waste-based cementitious material can consume 70%-95% of solid waste, which can reduce carbon emissions by more than 60% compared with cement.

[0023] The ecological pavement base material of the present application can meet the requirements of cement stabilized material base highway and first-class highway and light traffic in the Technical Details of Highway Pavement Base Construction (JTG / T G20-2015) after 7 days of maintenance, and the unconfined compressive strength can reach more than 3 MPa. DETAILED DESCRIPTION

[0024] The present application will be described in detail below through specific examples, and those skilled in the art can understand that the specific examples below are only for illustrative purposes and do not limit the scope of the present application in any way. In addition, in the following examples, unless otherwise specified, the reagents and equipment used are commercially available. If the specific treatment conditions and methods are not explicitly described in the following examples, the conditions and methods known in the art can be used for treatment.

[0025] In one aspect of the present application, the present application proposes a pavement base material, comprising the following components by weight parts: harmless barium residue 80-95 parts, solid waste-based cementitious material 5-20 parts and water 10-15 parts.

[0026] In the pavement base material of the present application, the only stabilized material is barium residue, which replaces natural sandstone with barium residue, realizes rapid and large-scale consumption of barium residue, improves the resource utilization rate of barium residue, and relieves the tension of road engineering sandstone; in addition, the solid waste-based cementitious material is used to replace cement as a stabilized material, which reduces the amount of cement used in road engineering and reduces the production cost of pavement base material.

[0027] In some embodiments of the present application, the solid waste-based cementitious material comprises slag, steel slag and desulfurization gypsum in a mass ratio of 60-70:20-30:10-20, and preferably, the specific surface area of the solid waste-based cementitious material is 450-500 m 2 / kg. The main components of the solid waste-based cementitious material are SiO225-30 parts, Al2O310-15 parts, CaO 30-40 parts, MgO 5-8 parts, SO30-5 parts, Fe2O38-12 parts, and loss on ignition 3-8 parts.

[0028] In the present application, the solid waste-based cementitious material is mainly a steel slag-slag-desulfurization gypsum cementitious material system, the desulfurization gypsum can stimulate the activity of steel slag and slag, and the steel slag and slag show a synergistic effect when they are hydrated, and the desulfurization gypsum is mainly composed of CaSO4·2H2O and a small amount of impurities. Since CaSO4 is slightly soluble in water, the soluble sulfate provided by the desulfurization gypsum can be used to fix free barium ions in the barium residue by precipitation, and the soluble calcium ions can react with sulfides or with hydroxyl ions.

[0029] The main mineral phases of steel slag are RO phase (a continuous solid solution formed by FeO, MgO, MnO and CaO), C2S, C3S, C4AF (calcium aluminoferrite), Fe2O3, and small amounts of Ca(OH)2, f-CaO (free calcium oxide) and f-MgO (free magnesium oxide). The divalent metal cations in steel slag are easily hydrated, making the system alkaline. These are the material basis for activating the formation of CSH gel in slag and tailings, and also the material basis for the formation of iron-containing calcite-aluminate complex salt minerals by removing Al2O3 and Fe2O3 from the slag with the participation of desulfurization gypsum.

[0030] Desulfurized gypsum provides a large amount of Ca for the reaction of the steel slag-blast furnace slag-desulfurized gypsum cementitious material system. 2+ and SO4 2- Under these conditions, steel slag undergoes slow hydration in its early stages, forming CHS gel and Ca. 2+ and OH - Simultaneously, it can rapidly increase the alkalinity within the slurry. At this time, the large amount of desulfurized gypsum and the alkaline environment will promote the dissociation of silicon (aluminum) oxygen tetrahedra in the slag, and the dissolved soluble silicon (aluminum) reacts with the Ca in the system. 2+ The formation of hydration products such as CSH gel and hydrated calcium sulfoaluminate (AFt) is achieved. As the hydration age increases, the steel slag continues to hydrate, generating a small amount of CSH gel and maintaining the alkalinity in the slurry. The overall slurry becomes denser, thus improving water stability.

[0031] Ca in the slag continuous hydration absorption system 2+ SO4 2- and OH - It can further promote the hydration of steel slag and promote the OH- - As the desulfurized gypsum dissolves, and the steel slag continues to react and the degree of hydration deepens, the needle-like AFt crystals of the hydration products are interspersed in the CSH gel, making the structure of the hardened paste more compact and increasing its compressive strength.

[0032] This invention utilizes the synergistic effect of steel slag, desulfurized gypsum, and blast furnace water-quenched slag to form a large number of needle-shaped complex salt crystals, as well as a large number of near-amorphous CSH gels and zeolite-like phases, which tightly encapsulate the needle-shaped complex salt crystals, making the originally loose structure compact, improving density, and enhancing water stability.

[0033] The application uses solid waste-based cementing material to replace cement for preparing pavement base materials, various indexes meet or even exceed cement concrete, meanwhile, the solid waste-based cementing material mainly contains minerals such as silicon, calcium and aluminum, is similar to soil geology, has lower alkalinity than cement-based materials, has smaller influence on ecological environment, has good solidification strength, low engineering cost and other advantages, can be widely used as road base stabilizing material, and fills the shortcomings of lime stabilizing materials such as early strength and low, cement stabilizing materials such as large dry shrinkage, and lime-fly ash stabilizing materials such as poor water stability.

[0034] In some embodiments of the application, the harmless barium residue comprises barium residue and desulfurization gypsum in a mass ratio of 70-90:10-30, wherein the barium residue is a solid waste discharged in a barium salt chemical process, and the desulfurization gypsum is a solid waste produced in a desulfurization workshop. The harmless barium residue of the application is composed of solid waste, realizes resource utilization of solid waste, and greatly reduces production cost.

[0035] Optionally, the particle size of the harmless barium residue is ≤4.75 mm; preferably, the particle size of the harmless barium residue is mostly 0.075-2.36 mm, the particles are fine, the distribution is uniform, and the grading is reasonable.

[0036] Optionally, the pH is 6-9, for example, can be pH=6, pH=7, pH=8 or pH=9.

[0037] Optionally, the toxic leaching concentration of barium ions in the harmless barium residue is <10 mg / L.

[0038] The limitation of the particle size, pH value and toxic leaching concentration of barium ions of the harmless barium residue can ensure that the leaching concentration of barium ions does not exceed the standard, and the strength of the harmless barium residue as aggregate can be ensured within the above range.

[0039] In another aspect of the application, the application further provides a preparation method of the pavement base material of any one of the above, comprising the following steps:

[0040] S100. Mix barium residue, desulfurization gypsum and water in proportion, and after steaming, dry and sieve to obtain harmless barium residue.

[0041] In this step, the steaming time is 20-28 h, for example, can be 20 h, 22 h, 25 h, 28 h, etc. The drying temperature is 50-60 DEG C, for example, can be 50 DEG C, 55 DEG C, 60 DEG C, etc.

[0042] S200. Weigh the harmless barium residue and solid waste-based cementing material in proportion, mix uniformly, and then perform compaction test to measure the maximum dry density and optimum moisture content.

[0043] S300. mixing the innocuous bar residue, the solid waste-based cementitious material and water in proportion to obtain the road base material.

[0044] In still another aspect of the present application, the present application further provides a use of the road base material of any one of the above or the road base material prepared by the method of any one of the above in a road material.

[0045] Embodiment 1

[0046] The embodiment provides an ecological road base material, which comprises the following components in parts by weight: 94 parts of innocuous bar residue, 6 parts of solid waste-based cementitious material and 12.0 parts of tap water.

[0047] The solid waste-based cementitious material comprises 6 parts of slag, 3 parts of steel slag and 1 part of desulfurization gypsum by mass fraction, and has a specific surface area of 450 m 2 / kg. The innocuous bar residue has a particle size of less than 4.75 mm, and comprises 10 parts of bar residue and 1 part of desulfurization gypsum by mass fraction, and has a pH of 6 and a bar ion toxicity leaching concentration of less than 10 mg / L.

[0048] The preparation method of the road base material is as follows:

[0049] (1) mixing the bar residue and the desulfurization gypsum in proportion, adding water, stirring uniformly, performing material soaking for 20 hours, and then drying at 50 DEG C to obtain the innocuous bar residue, wherein the innocuous bar residue is obtained by sieving the dried material to retain the fine particles (particle size of 85% is between 0.075-4.75 mm);

[0050] (2) mixing the innocuous bar residue and the solid waste-based cementitious material in proportion by mass, and performing compaction test to obtain the maximum dry density p max = 1.90 g / cm 3 and the optimum water content MC 最佳 = 12.4%;

[0051] (3) mixing the innocuous bar residue and the solid waste-based cementitious material in proportion by mass to obtain the mixture, adding water to the stirred mixture, and mixing uniformly to obtain the mixture;

[0052] (4) stirring the mixture uniformly, pouring into a mold, and obtaining the ecological road base material after demolding;

[0053] The ecological road base material is used to form a product, the product is demolded, and then is placed into a standard curing box with a temperature of 20±1 DEG C and a relative humidity of 95% for curing for 7 days and 28 days and water curing for 1 day, and is used for subsequent test and test.

[0054] Embodiment 2

[0055] The embodiment provides an ecological road base material, which comprises the following components in parts by weight: 92 parts of harmless barium residue, 8 parts of solid waste-based cementitious material and 12.8 parts of water.

[0056] The solid waste-based cementitious material comprises 6 parts of slag, 3 parts of steel slag and 1 part of desulfurization gypsum, and has a specific surface area of 460 m 2 / kg.

[0057] The preparation method of the road base material is as follows:

[0058] (1) The barium residue and the desulfurization gypsum are mixed in a certain proportion, and then water is added and stirred uniformly, and then the material is steamed for 22 hours, and then dried at 52 DEG C, and then the fine particle barium residue is screened out, that is, the harmless barium residue is obtained;

[0059] (2) The harmless barium residue and the solid waste-based cementitious material are weighed in a certain mass ratio, mixed uniformly, and then subjected to compaction test, and the maximum dry density rho max is 1.92 g / cm 3 , and the optimum moisture content MC 最佳 is 12.8%;

[0060] (3) The harmless barium residue and the solid waste-based cementitious material are weighed and mixed uniformly to obtain a mixture, and then water is added to the mixture and stirred uniformly, and then the mixture is obtained;

[0061] (4) The mixture is stirred uniformly and poured into a mold, and then the ecological road base material is obtained after demolding.

[0062] The ecological road base material prepared above is used for molding, and then the product after molding is demolded, and then placed in a standard curing box with a temperature of 20+ / -1 DEG C and a relative humidity of 95% for curing for 7 days, 28 days and 1 day of water curing, and then used for subsequent test and test.

[0063] Example 3

[0064] The embodiment provides an ecological road base material, which comprises the following components in parts by weight: 92 parts of harmless barium residue, 8 parts of solid waste-based cementitious material and 12.8 parts of water.

[0065] The solid waste-based cementitious material comprises 6 parts of slag, 3 parts of steel slag and 1 part of desulfurization gypsum, and has a specific surface area of 460 m 2kg; the particle size of the harmless barium residue is below 4.75 mm, and the composition of the harmless barium residue in mass fraction is 10 parts of barium residue and 1 part of desulfurization gypsum; the pH of the harmless barium residue is 7, and the toxic leaching concentration of barium ions is less than 10 mg / L.

[0066] The preparation method of the road base material is as follows:

[0067] (1) After the barium residue and the desulfurization gypsum are mixed in proportion, water is added, and the mixture is stirred uniformly, then the mixture is steamed for 23.5 hours, and then the mixture is dried at 55°C; the fine particles of the barium residue are screened out after drying, and the fine particles are the harmless barium residue;

[0068] (2) The harmless barium residue and the solid waste-based cementitious material are weighed in proportion, and then the mixture is uniformly mixed and subjected to a compaction test; the maximum dry density p max is 1.94 g / cm 3 , and the optimum moisture content MC 最佳 is 13.2%;

[0069] (3) The harmless barium residue and the solid waste-based cementitious material are weighed and uniformly mixed to obtain a mixture; water is added to the uniformly mixed mixture, and the mixture is uniformly mixed to obtain a mixture;

[0070] (4) The mixture is uniformly stirred and poured into a mold; after demolding, the ecological road base material is obtained.

[0071] The ecological road base material prepared above is molded, the molded product is demolded, and then the product is placed in a standard curing box with a temperature of 20±1°C and a relative humidity of 95% for curing for 7 days and 28 days, and water curing for 1 day, for subsequent test and test.

[0072] Example 4

[0073] The ecological road base material provided in this embodiment includes the following components in weight fraction: 88 parts of harmless barium residue, 12 parts of solid waste-based cementitious material, and 13.6 parts of tap water.

[0074] The composition of the solid waste-based cementitious material in mass fraction is 6 parts of slag, 3 parts of steel slag, and 1 part of desulfurization gypsum, and the specific surface area is 490 m 2 / kg; the particle size of the harmless barium residue is below 4.75 mm, and the composition of the harmless barium residue in mass fraction is 10 parts of barium residue and 1 part of desulfurization gypsum; the pH of the harmless barium residue is 9, and the toxic leaching concentration of barium ions is less than 10 mg / L.

[0075] The preparation method of the road base material is as follows:

[0076] (1) the barium residue is mixed with desulfurization gypsum according to a proportion, water is added, stirring is uniformly conducted, and then the material is soaked for 26 hours, and then the soaked material is dried at 58 DEG C, the fine particles of the dried material are screened and reserved, and the fine particles are harmless barium residue;

[0077] (2) the harmless barium residue and the solid waste-based cementing material are uniformly mixed according to a mass ratio, and then a compaction test is conducted, and the maximum dry density p max is 1.97 g / cm 3 , and the optimum moisture content MC 最佳 is 13.6%;

[0078] (3) the harmless barium residue and the solid waste-based cementing material are uniformly mixed to obtain a mixture, and then water is added to the mixture, and the mixture is uniformly stirred to obtain a mixture;

[0079] (4) the mixture is uniformly stirred and poured into a mold, and then an ecological road base material is obtained after demolding.

[0080] The ecological road base material prepared above is molded, the molded product is demolded, and then the product is placed in a standard curing box with a temperature of 20 DEG C ± 1 DEG C and a relative humidity of 95% for curing for 7 days and 28 days, and water curing for 1 day, and then the product is used for subsequent test and test.

[0081] Example 5

[0082] The ecological road base material provided in the example comprises the following components in parts by weight: 86 parts of harmless barium residue, 14 parts of solid waste-based cementing material, and 14 parts of tap water.

[0083] The solid waste-based cementing material comprises 6 parts of slag, 3 parts of steel slag, and 1 part of desulfurization gypsum, and the specific surface area of the desulfurization gypsum is 500 m 2 / kg; the particle size of the harmless barium residue is less than 4.75 mm, the harmless barium residue comprises 10 parts of barium residue and 1 part of desulfurization gypsum, the pH of the harmless barium residue is 8, and the barium ion toxicity leaching concentration is less than 10 mg / L.

[0084] The preparation method of the road base material is as follows:

[0085] (1) the barium residue is mixed with desulfurization gypsum according to a proportion, water is added, stirring is uniformly conducted, and then the material is soaked for 28 hours, and then the soaked material is dried at 60 DEG C, the fine particles of the dried material are screened and reserved, and the fine particles are harmless barium residue;

[0086] (2) the harmless barium residue and the solid waste-based cementing material are uniformly mixed according to a mass ratio, and then a compaction test is conducted, and the maximum dry density p max is 1.98 g / cm 3 , and the optimum moisture content MC 最佳 is 14%.

[0087] (3) weighing the harmless barium residue and the solid waste-based cementitious material, mixing them evenly to obtain a mixture, and adding water to the mixture and stirring evenly to obtain a mixture;

[0088] (4) stirring the mixture evenly and pouring it into a mold, and obtaining an ecological road base material after demolding.

[0089] The ecological road base material prepared above is molded, the product after molding is demolded, and then placed in a standard curing box with a temperature of 20±1℃ and a relative humidity of 95% for curing for 7d and 28d, and water curing for 1d, for subsequent test and test.

[0090] The ecological road base material prepared in Examples 1-5 is used to prepare a Ф50mm×50mm cylindrical test piece according to the unconfined compressive strength test requirements for inorganic binder stabilized materials in the Highway Engineering Inorganic Binder Stabilized Material Test Specification (JTGE51-2009), at least 6 for each group; after preparation, it is sealed and placed in a curing box (curing temperature is 20±1℃, curing humidity is 95%), and cured for 7d and 28d (soaked in water one day in advance), after completion, the surface moisture of the test piece is wiped dry, and the compressive strength of the test piece is tested by using a road strength instrument, and the test results are shown in Table 1.

[0091] Table 1

[0092]

[0093]

[0094] As can be seen from Table 1, the road base material prepared by using the harmless barium residue and the solid waste-based cementitious material has good compressive strength, and can reach the standard of secondary and above secondary highway or high-speed and first-class highway.

[0095] In summary, in the road base material of the present application, the stabilizing material is a solid waste-based cementitious material, and the stabilized material is only a harmless barium residue, realizing the resource utilization of various industrial waste residues, effectively taking into account the mechanical properties, durability and water stability of the obtained road base material, etc.; and realizing large-scale utilization of barium residue, improving the resource utilization rate of barium residue, relieving the tension of road engineering sand and gravel, reducing the amount of cement, the preparation process is simple, suitable for a wide range of applications, and has significant economic and environmental benefits.

[0096] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and that changes, modifications, substitutions and variations can be made by those skilled in the art without departing from the scope of the present application.

Claims

1. A road base material, characterised in that, The road base material comprises the following components by weight parts: 80-95 parts of harmless barium residue, 5-20 parts of solid waste-based cementitious material and 10-15 parts of water, The solid waste-based cementitious material comprises the following components by weight parts: 60-70 parts of slag, 20-30 parts of steel slag and 10-20 parts of desulfurization gypsum, The harmless barium residue comprises the following components by weight parts: 70-90 parts of barium residue and 10-30 parts of desulfurization gypsum.

2. The pavement base material of claim 1, wherein, The specific surface area of the solid waste-based cementitious material is 450-500 m 2 / kg.

3. The pavement base material of claim 1, wherein, The particle size of the harmless barium residue is less than or equal to 4.75 mm, and the pH is 6-9. The barium ion toxicity leaching concentration in the harmless barium residue is less than 10 mg / L.

4. The pavement base material of claim 3, wherein, The particle size of the harmless barium residue is 0.075-2.36 mm.

5. The pavement base material of claim 1, wherein, The barium residue is a solid waste discharged in a barium salt chemical process, and the desulfurization gypsum is a solid waste produced in a desulfurization workshop.

6. A method of producing a road base material as claimed in any one of claims 1 to 5, characterised in that, The method comprises the following steps: (1) mixing the barium residue, the desulfurization gypsum and water uniformly, and then drying and sieving after steaming, to obtain the harmless barium residue; (2) mixing the harmless barium residue, the solid waste-based cementitious material and water uniformly, to obtain the road base material.

7. The method of claim 6, wherein the base material is prepared by mixing the aggregate, the binder, and the water, and then heating the mixture to a temperature of 100 to 200°C. The steaming time is 20-28 h; The drying temperature is 50-60 DEG C, and the water content is less than 2% after drying.

8. Application of the road base material of any one of claims 1-5 or the road base material prepared by the method of any one of claims 6-7 in road materials.

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