A green pavement concrete based on lead smelting slag and its preparation method

Abstract

This invention discloses a green pavement concrete based on lead smelting slag and its preparation method, belonging to the fields of solid waste treatment and green pavement concrete. It comprises the following raw materials in parts by weight: 52.5-122.5 parts lead smelting slag, 122.5 parts cement clinker, 84-154 parts mineral powder, 21 parts desulfurized gypsum, 627-784 parts river sand, 1176-1333 parts crushed stone, and 126-154 parts water. The concrete has a slump of 38 mm, meeting actual construction requirements. Its 3-day flexural strength is 4.21 MPa, and its 28-day strength is 7.15 MPa, far exceeding the design requirements for flexural strength of medium and light load pavements; its 3-day compressive strength is 41.5 MPa, and its 28-day strength is 58.4 MPa, meeting the C50 concrete strength requirements; and its abrasion resistance is 3.840 kg / m³. 3 It meets the wear requirements for surface concrete of Class III and IV highways.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid waste treatment and green pavement concrete, and particularly relates to lead smelting slag-based green pavement concrete and a preparation method thereof. BACKGROUND

[0002] In recent years, with the continuous development of lead smelting industry, a large amount of lead smelting slag with low utilization rate is generated. According to statistics, 7100 kg of lead slag is discharged for every ton of lead produced in the lead smelting system. The piling of lead smelting slag not only occupies land resources, but also releases heavy metal ions, causing serious environmental pollution. Therefore, the resource utilization of lead smelting slag has become one of the environmental protection problems that need to be solved at present.

[0003] With the rapid economic development, the demand for highway construction is increasing, and therefore higher requirements are put forward for pavement materials. The most commonly used pavement cementing material is cement, but the cement industry is a resource-intensive and high-energy-consumption industry. The production of one ton of cement consumes about 235 kg of standard coal and about 100 degrees of electricity, and at the same time, a large amount of CO2 is generated. The durability of traditional pavement cementing materials such as cement is far lower than the design life, and premature damage is common. Therefore, it is urgent to develop a new type of green pavement concrete that can meet the working performance, has superior durability and bearing capacity, can reduce environmental pollution, and meets the requirements of energy saving and emission reduction. SUMMARY

[0004] In view of the problems in the prior art, the application provides a lead smelting slag-based green pavement concrete and a preparation method thereof.

[0005] To achieve the above-mentioned purpose, the application provides the following technical scheme:

[0006] The lead smelting slag-based green pavement concrete comprises the following raw materials in mass fraction: lead smelting slag micro powder 52.5-122.5 parts, cement clinker 122.5 parts, mineral powder 84-154 parts, desulfurization gypsum 21 parts, river sand 627-784 parts, crushed stone 1176-1333 parts, and water 126-154 parts.

[0007] Preferably, the raw materials further comprise an additive, and the additive is added in an amount of 0.35-0.60% of the total mass of cementing materials (lead smelting slag micro powder + cement clinker + mineral powder + desulfurization gypsum).

[0008] More preferably, the additive is Shaanxi Youbang YB-513 polycarboxylic acid superplasticizer mother liquor with a solid content of 40%.

[0009] Preferably, the lead smelting slag micro powder is obtained by ball milling the waste slag produced by smelting lead-zinc ore for 2 h, and the main particle size is D 10=3.485μm, D 50 =28.336μm, D 90 =86.281μm.

[0010] This invention adds lead smelting slag to concrete. The lead smelting slag is ground in a ball mill for 2 hours, which increases its fineness and specific surface area. The potential cementitious activity of the lead smelting slag is activated through physical stimulation, so that this solid waste can replace part of the cement as a cementitious material component. It can also generate cementitious activity under the stimulation of cement clinker, slag, gypsum and other solid wastes, so it can be used to prepare green pavement concrete based on lead smelting slag.

[0011] Preferably, the cement clinker is obtained by crushing clinker blocks with a jaw crusher and grinding them in a ball mill for 70 minutes, with a specific surface area of ​​365 m². 2 / kg, with the main particle size being D 10 =2.637μm, D 50 =22.453μm, D 90 =83.712μm.

[0012] Preferably, the main particle size of the mineral powder is D. 10 =2.037μm, D 50 =9.742μm, D 90 =26.027μm.

[0013] Preferably, the fineness modulus of the river sand is 2.57.

[0014] Preferably, the crushed stone is continuously graded and has a particle size of 4.75-19.0 mm.

[0015] This invention also provides a method for preparing the lead smelting slag-based green pavement concrete, comprising the following steps:

[0016] Weigh out the lead smelting slag powder, cement clinker, mineral powder, desulfurized gypsum, river sand, crushed stone, water, and admixtures according to the specified mass proportions. Put the river sand and crushed stone into a moistened mixer and mix for 60 seconds. Then add the lead smelting slag powder, cement clinker, mineral powder, and desulfurized gypsum. While mixing, add water (90% of the total mass of water) and mix for 60 seconds. Then add the remaining water containing the admixtures to the mixture and mix for another 60 seconds. Pour the mixture into a mold and vibrate to form the concrete. After bonding and curing, remove the mold and perform standard curing to obtain lead smelting slag-based green pavement concrete.

[0017] Preferably, the bonding and curing refers to curing at room temperature.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] Lead smelting slag has a slow hydration rate. Increasing the lead slag content indirectly reduces the water demand of the cementitious materials, leading to an overall increase in the slump of the concrete. This is more conducive to molding and compaction, reducing porosity, increasing density, and improving various performance indicators. The fine lead smelting slag obtained after grinding has a smaller particle size and a larger specific surface area. Under the action of clinker, mineral powder, and gypsum, its potential cementitious activity is activated, resulting in hydration and mechanical strength. Furthermore, lead slag has high hardness and high iron content, which improves the wear resistance of concrete. This technology provides a solution for the widespread utilization of lead smelting slag, effectively addressing the problems of huge amounts of solid waste generated by the lead-zinc smelting industry, serious resource waste, unsustainable industry development, and environmental pollution.

[0020] This invention increases the amount of lead smelting slag in the solid waste material (122.5 kg of lead smelting slag powder, accounting for 35% of the total mass of the cementitious material); the amount of river sand is 784 kg, with a sand ratio of 40%; the amount of water is 126 kg, with a water-cement ratio of 0.36; and the amount of water-reducing agent is 0.60% of the total mass of the cementitious material. The slump is 38 mm, which meets the actual construction requirements. The 3-day flexural strength is 4.21 MPa, and the 28-day strength is 7.15 MPa, far exceeding the design requirements for flexural strength of medium and light load pavements; the 3-day compressive strength is 41.5 MPa, and the 28-day strength is 58.4 MPa, meeting the strength requirements of C50 concrete; and the abrasion resistance is 3.840 kg / m². 3 It meets the wear requirements for surface concrete of Class III and IV highways. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0022] Figure 1 The XRD pattern of lead smelting slag powder is shown in the embodiment of the present invention.

[0023] Figure 2 This is a particle size distribution diagram of lead smelting slag powder according to an embodiment of the present invention;

[0024] Figure 3 The XRD pattern of cement clinker in an embodiment of the present invention;

[0025] Figure 4 This is a particle size distribution diagram of cement clinker in an embodiment of the present invention;

[0026] Figure 5 The XRD pattern of the mineral powder in an embodiment of the present invention;

[0027] Figure 6 This is a particle size distribution diagram of the mineral powder in an embodiment of the present invention;

[0028] Figure 7 The XRD pattern of desulfurized gypsum in an embodiment of the present invention;

[0029] Figure 8 This is a flowchart illustrating the process for preparing green concrete based on lead smelting slag, as described in an embodiment of the present invention.

[0030] Figure 9 SEM images of the cementitious material prepared in Example 1 of this invention at 3d(a) and 28d(b). Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0036] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0037] All raw materials used in the following embodiments of the present invention are commercially available.

[0038] This invention provides a green pavement concrete based on lead smelting slag, comprising the following raw materials in parts by weight: 52.5-122.5 parts lead smelting slag powder, 122.5 parts cement clinker, 84-154 parts mineral powder, 21 parts desulfurized gypsum, 627-784 parts river sand, 1176-1333 parts crushed stone, and 126-154 parts water. In a further preferred embodiment, the green pavement concrete based on lead smelting slag comprises the following raw materials in parts by weight: 122.5 parts lead smelting slag powder, 122.5 parts cement clinker, 84 parts mineral powder, 21 parts desulfurized gypsum, 784 parts river sand, 1176 parts crushed stone, and 126 parts water.

[0039] In the following embodiments of the present invention, the raw materials further include an admixture, the amount of which is 0.35-0.60% of the total mass of the cementitious materials (lead smelting slag powder + cement clinker + mineral powder + desulfurization gypsum), preferably 0.60%. The admixture is Shaanxi Youbang admixture, specifically YB-513 polycarboxylate superplasticizer with a solid content of 40%.

[0040] In the following embodiments of the present invention, the lead smelting slag powder used is obtained from waste slag produced by Qinghai Xiyu Nonferrous Metals Co., Ltd. from lead-zinc ore smelting, and is obtained by grinding in a ball mill for 2 hours, with a grinding work index W. i The efficiency is 27.96 kW·h / t. The main chemical composition is shown in Table 1, and the mineral composition is as follows: Figure 1 As shown, the slag contains magnetite (Fe3O4) and ferroalloy (FeO), and a distinct amorphous peak is observed near 30°, indicating the presence of glassy particles and potential cementing activity. The particle size distribution of the lead smelting slag powder is shown in the figure. Figure 2 As shown, the main particle size D 10 =3.485μm, D 50 =28.336μm, D 90 =86.281μm.

[0041] Table 1. Chemical composition (wt.%) of lead smelting slag powder

[0042]

[0043] In the following embodiments of the present invention, the cement clinker comes from Shengwei Cement Plant in Tongchuan, Shaanxi Province. The clinker blocks are crushed by a jaw crusher and ground in a ball mill for 70 minutes to obtain a specific surface area of ​​365 m². 2 / kg of cement clinker powder. Its main chemical composition is shown in Table 2, and its mineral composition is as follows: Figure 3 As shown, the main components are C3S, C2S, C3A, and C4AF. The particle size distribution of cement clinker powder is as follows: Figure 4 As shown, the main particle size D 10 =2.637μm, D50 =22.453μm, D 90 =83.712μm.

[0044] Table 2 Chemical composition of cement clinker (wt.%)

[0045]

[0046] In the following embodiments of the present invention, the mineral powder is from Xi'an Delong Powder Engineering Materials Co., Ltd. Its main chemical composition is shown in Table 3, and its mineral composition is as follows: Figure 5 As shown, the peaks around 30° indicate the presence of a glassy body, with the main mineral phases being magnesian feldspar and magnesian rhodochrosite. The particle size distribution of the mineral powder is as follows: Figure 6 As shown, the main particle size D 10 =2.037μm, D 50 =9.742μm, D 90 =26.027μm.

[0047] Table 3 Chemical composition of mineral powder (wt.%)

[0048]

[0049] In the following embodiments of the present invention, the desulfurized gypsum is sourced from Shaanxi Tongchuan Shengwei Cement Plant. Its main chemical composition is shown in Table 4, and its mineral composition is as follows: Figure 7 As shown, the main mineral phases are dihydrate gypsum and hemihydrate gypsum.

[0050] Table 4 Chemical composition of desulfurized gypsum (wt.%)

[0051]

[0052] In the following embodiments of the present invention, the fineness modulus of the river sand is 2.57, which is medium sand; the crushed stone gradation is 4.75-19.0mm, which is composed of two single-size particles (A: 4.75-9.5mm, B: 9.5-19.0mm), wherein A accounts for 40% and B accounts for 60%.

[0053] This invention also provides a method for preparing the lead smelting slag-based green pavement concrete (see [link]). Figure 8 In the following embodiments of the present invention, the preparation and curing of concrete specimens before demolding are completed indoors at room temperature, and the specimens are cured in a standard curing room after demolding. The specific preparation steps and precautions for the specimens are as follows:

[0054] (1) Cleaning of molds: In order to reduce the problem of difficult demolding caused by the adhesion between the slurry and the bottom and sides of the mold when mixing and molding the green pavement concrete based on lead smelting slag, it is necessary to clean the residual slurry around the mold and the bottom of the mold with a scraper and sandpaper before each use to prevent adverse effects on the surface of the molded test block; in addition, water-based release agent was brushed onto the inner surface of the mold one day in advance for this experiment. The release agent should be dried before molding to make the test block smooth and flat, and easy and convenient to demold.

[0055] (2) Weighing materials: Use an electronic scale to weigh the required sand, gravel, water and other raw materials in sequence.

[0056] (3) Mixing: In order to ensure that the test materials can be mixed evenly after mixing, when making green pavement concrete test blocks based on lead smelting slag, the mixer was pre-wetted first, and then coarse aggregate gravel and fine aggregate river sand were poured into the pre-wetted mixer (in order to prevent the inner wall of the machine from being too dry during mixing and affecting the workability of the mixture, the mixer was pre-wetted in advance, and the total amount of water used during pre-wetting and mixing was equal to the calculated amount of the mix proportion). After the mixer was covered, it was mixed for about 60 seconds. Then the cementitious materials (referring to lead smelting slag powder, cement clinker, mineral powder and desulfurization gypsum) were added and mixed for 60 seconds to ensure that the aggregate and cementitious materials were in full contact and mixed evenly. Then, 90% of the water was added steadily while mixing and mixed for 60 seconds. Finally, the remaining 10% of the water was mixed with the required water-reducing agent and added steadily while mixing and mixed for 60 seconds.

[0057] (4) Testing the slump of fresh concrete: After mixing the lead smelting slag-based green pavement concrete slurry in the mixer, stir it manually with a shovel for 1 minute. Then, evenly fill the concrete mixture into the slump cone in three layers. After each layer of concrete mixture is filled, use a tamping rod to evenly tamp it 25 times in a spiral motion from the edge to the center. After tamping, the height of each layer of concrete mixture should be about 1 / 3 of the cone height. After tamping the top layer, remove the filling funnel, scrape off the excess concrete mixture, and smooth it along the cone opening. Scrape the mixture around the bottom of the cone clean, and then immediately lift the slump cone vertically. The lifting of the cone should be completed within 3-7 seconds, ensuring that the concrete is not subjected to lateral or torsional forces. The entire process from the start of filling to the removal of the slump cone should be completed within 150 seconds. Finally, measure the concrete slump to see if it meets the design requirements. If it does, proceed with the pouring and molding.

[0058] (5) Specimen casting and molding: The mixed lead smelting slag-based green pavement concrete slurry is evenly poured into a cleaned mold, filling the mold completely with a slight surplus. The mold is placed on a standard vibrating table, and the vibrating table is turned on until a milky cement slurry appears on the concrete surface. Concrete is added continuously during vibration to keep the mold full, and the vibration time is recorded (generally not exceeding 90 seconds). After vibration, excess concrete is scraped off along the edge of the mold with a metal ruler, and the surface is initially smoothed with a trowel. After the specimen has settled, it is carefully smoothed again with a trowel. The height difference between the specimen surface and the edge of the mold should not exceed 0.5 mm.

[0059] (6) Curing of the test blocks. After the concrete test blocks are formed, cover the surface of the test blocks with plastic wrap to keep them moist. Let them stand for one day at a room temperature of 20℃±5℃ and a relative humidity greater than 50%. Then, remove the mold and perform a visual inspection and numbering. After demolding, place the test specimens in a standard curing room with a temperature of 20±5℃ and a humidity of not less than 95% for curing until the required curing age is reached. The mold specifications used in the following embodiments of the present invention are 100mm×100mm×100m and 100mm×100mm×400m.

[0060] The following embodiments are further illustrations of the technical solution of the present invention.

[0061] Examples 1-6

[0062] A method for preparing lead smelting slag-based green pavement concrete, comprising the following steps:

[0063] Weigh the raw materials according to the mass shown in Table 5. First, mix the river sand and crushed stone for 60 seconds. Then, add lead smelting slag powder, cement clinker, mineral powder and desulfurized gypsum, and mix for 60 seconds. Then, while mixing, add 90% of the water and mix for another 60 seconds. Finally, while mixing, add the remaining 10% of the water and the required water-reducing agent mixture and mix for another 60 seconds. Then, place the mixture with the measured slump that meets the requirements into a mold and vibrate for about 60 seconds. Place the specimen in an indoor environment with a temperature of 20±5℃ and a humidity of more than 50% for curing. After curing for 1 day, remove the mold and then carry out normal temperature curing in a standard curing room (temperature of 20±2℃, humidity of 95%, curing time of 3 days and 28 days) to obtain lead smelting slag-based green pavement concrete.

[0064] Table 5. Mix proportions of experimental concrete

[0065]

[0066] Performance testing:

[0067] The concrete prepared for the above tests was subjected to performance testing, and the testing methods were as follows:

[0068] (1) Slump: After lifting the concrete slump cone, place it next to the cone concrete sample, place the tamping rod flat on the top of the cone, and use a steel ruler to measure the vertical distance from the bottom of the tamping rod to the highest point of the top surface of the sample. This is the slump of the concrete mixture.

[0069] (2) Flexural Strength: The flexural strength of concrete is tested according to the "Test Method for Flexural Strength of Cement Concrete" in "JTG 3420-2020 Highway Engineering Cement and Cement Concrete Test Procedures" (T 0558-2005). The surface of a 100mm×100mm×400mm concrete specimen, cured to the specified age, is cleaned. The specimen is placed on the support with the side facing upwards. After geometric alignment, the contact surface between the support and the bearing surface and the movable boat-shaped pad should be stable and uniform; otherwise, it should be leveled. Loading should be uniform and continuous. When the concrete strength grade is greater than or equal to C30 and less than C60, the loading rate is 0.05-0.08 MPa / s. When the specimen approaches failure and begins to deform rapidly, the throttle of the testing machine should not be adjusted until the specimen fails. The failure limit load is recorded, and the average value of three specimens in a group is taken. Then, multiply by the conversion factor 0.85 to obtain the standard value of the flexural strength of that group of specimens.

[0070] (3) Compressive strength: The compressive strength of concrete is tested according to the "Test Method for Compressive Strength of Cement Concrete" (T 0553-2005) in the "Test Procedure for Cement and Cement Concrete of Highway Engineering" (JTG 3420-2020). The surface of a 100mm×100mm×100mm concrete specimen cured to the specified age is cleaned, with the upper and lower bearing plates cleaned. The side is used as the upper and lower bearing surfaces during molding, and the center of the specimen is geometrically aligned with the press. For concrete strength grades ≥C30 and <C60, the loading rate is 0.5-0.8MPa / s. When the specimen approaches failure and begins to deform rapidly, the throttle of the testing machine should be stopped and adjusted until failure occurs. The failure load is then recorded. The average value of three specimens in a set is taken, and then multiplied by a conversion factor of 0.95 to obtain the standard value of the compressive strength of that set of cubic specimens.

[0071] (4) Abrasion Resistance: The flexural strength of concrete was tested according to the "Test Method for Bending Tensile Strength of Cement Concrete" in "JTG 3420-2020 Highway Engineering Cement and Cement Concrete Test Procedure" (T 0567-2005). 150mm×150mm×150mm concrete specimens cured to 27 days were removed from the curing location, wiped dry, and allowed to air dry naturally for 12 hours. Then, they were placed in a 60℃±5℃ oven and dried for 12 hours until constant weight. After drying, the specimens were placed at room temperature and the surface dust was brushed off. The specimens were placed on the horizontal turntable of the abrasion testing machine (the grinding surface should be perpendicular to the top surface during molding) and gently secured with clamps. The specimens were first ground for 30 revolutions under a 200N load, then removed, the surface dust was brushed off, and the specimen was weighed. The corresponding mass was recorded as m1, which was taken as the initial mass of the specimen. Then, grind under a load of 200N for 60 revolutions, remove the specimen, brush off the surface dust, weigh it, and record the remaining mass as m2. Then, according to the formula G... c The wear amount of the test block was calculated as (m1-m2) / 0.0125, and the arithmetic mean of the wear amounts of the three test blocks was taken as the test result. The results are shown in Table 6.

[0072] Table 6 Performance Test Results

[0073]

[0074] As can be seen from Table 5, the total amount of cementitious material in Examples 1, 2 and 3 is 350 kg, of which 122.5 kg is lead smelting slag powder, which is 35% of the total cementitious material. All admixtures used are Shaanxi Youbang YB-513 polycarboxylate high-efficiency water-reducing agent. The dosage of water-reducing agent needs to be adjusted appropriately to meet the construction requirements.

[0075] In Example 1, the amount of river sand used was 784 kg, with a sand ratio of 40%; the amount of water used was 126 kg, with a water-cement ratio of 0.36; the water-reducing agent dosage was 0.60% of the cementitious material; and the slump was 38 mm, meeting the actual construction requirements. The 3-day flexural strength was 4.21 MPa, and the 28-day strength was 7.15 MPa; the 3-day compressive strength was 41.5 MPa, and the 28-day strength was 58.4 MPa; the abrasion resistance was 3.840 kg / m². 3 .

[0076] Compared to Example 1, Example 2 used 627 kg of river sand (32% sand ratio), 140 kg of water (0.40 water-cement ratio), and 0.45% water-reducing agent as part of the cementitious material. The slump was 35 mm, meeting actual construction requirements. The 3-day flexural strength was 3.79 MPa, and the 28-day strength was 6.30 MPa; the 3-day compressive strength was 39.1 MPa, and the 28-day strength was 56.4 MPa; the abrasion resistance was 4.240 kg / m². 3 .

[0077] Compared to Example 1, Example 3 used 706 kg of river sand (36% sand ratio), 154 kg of water (0.44 water-cement ratio), and 0.35% water-reducing agent as a percentage of the cementitious material. The slump was 39 mm, meeting actual construction requirements. The 3-day flexural strength was 3.73 MPa, and the 28-day strength was 4.99 MPa; the 3-day compressive strength was 34.5 MPa, and the 28-day strength was 49.4 MPa; the abrasion resistance was 6.320 kg / m². 3 .

[0078] Figure 9 SEM images of the samples prepared from the cementitious material components of Examples 1-3, from... Figure 9 As can be seen in (a) of the sample containing 35% lead smelting slag powder, at 3 days of age, the various cementitious materials in the sample had undergone hydration reactions, forming a loose network gel and relatively neatly arranged short rod-shaped calcium vanadate stones with obvious pores. Figure 9 As can be seen in (b), by the 28-day period, the interior of the sample is more compact, the surface gel increases significantly, and they are tightly connected to form a dense honeycomb structure, which plays a supporting role in the skeleton, demonstrating that the 28-day sample has higher macroscopic mechanical properties.

[0079] Example 4 differs from Example 1 in that it contains a smaller amount of lead smelting slag (52.5 kg of lead smelting slag powder, representing 15% of the total cementitious materials); and 627 kg of river sand, with a sand ratio of 32%. The results showed that the concrete prepared using this example had a slump of 28 mm, meeting actual construction requirements; a 3-day flexural strength of 4.71 MPa and a 28-day strength of 8.05 MPa; a 3-day compressive strength of 51.3 MPa and a 28-day strength of 64.7 MPa; and an abrasion resistance of 3.920 kg / m². 3 .

[0080] Example 5 differs from Example 1 in that it contains a smaller amount of lead smelting slag (52.5 kg of lead smelting slag powder, representing 15% of the total cementitious materials); and 706 kg of river sand, with a sand ratio of 34%. The results showed that the concrete prepared using this example had a slump of 20 mm, meeting actual construction requirements; a 3-day flexural strength of 4.42 MPa and a 28-day strength of 7.67 MPa; a 3-day compressive strength of 48.9 MPa and a 28-day strength of 64.7 MPa; and an abrasion resistance of 5.200 kg / m². 3 .

[0081] Example 6 differs from Example 1 in that it contains a smaller amount of lead smelting slag (52.5 kg of lead smelting slag powder, representing 15% of the total cementitious materials); and 784 kg of river sand, with a sand ratio of 40%. The results showed that the concrete prepared using this example had a slump of 36 mm, meeting actual construction requirements; a 3-day flexural strength of 4.13 MPa and a 28-day strength of 6.83 MPa; a 3-day compressive strength of 42.5 MPa and a 28-day strength of 55.3 MPa; and an abrasion resistance of 6.640 kg / m². 3 .

[0082] In summary, the green pavement concrete based on lead smelting slag powder, with a cementitious material content of 35% and a water-cement ratio of 0.36 in Example 1, exhibited a slump of 38 mm, a 28-day flexural tensile strength of 7.15 MPa, a 28-day compressive strength of 58.4 MPa, and an abrasion resistance of 3.840 kg / m³. 3 The working performance meets the construction requirements, and the mechanical properties meet the medium load requirements of the design. The working performance and wear resistance are better than those of Example 4, and the lead slag utilization is higher, which is in line with the original design intention of green concrete.

[0083] Example 2: Lead smelting slag powder was added to the cementitious material at a dosage of 35%, and the water-cement ratio was 0.40. The resulting green pavement concrete based on lead smelting slag had a slump of 35 mm, a 28-day flexural tensile strength of 6.30 MPa, a 28-day compressive strength of 56.4 MPa, and an abrasion resistance of 4.240 kg / m³. 3 The working performance meets the construction requirements, and the mechanical properties meet the medium load requirements of the design. The working performance and wear resistance are better than those of Example 5, and the lead slag utilization is higher, which is in line with the original design intention of green concrete.

[0084] Example 3: Lead smelting slag powder was added to the cementitious material at a dosage of 35%, and the water-cement ratio was 0.44. The resulting green pavement concrete based on lead smelting slag had a slump of 39 mm, a 28-day flexural tensile strength of 4.99 MPa, a 28-day compressive strength of 49.4 MPa, and an abrasion resistance of 6.320 kg / m³. 3 The working performance meets the construction requirements, and the mechanical properties meet the design requirements for medium loads. The working performance and wear resistance are superior to those of Example 6, and the lead slag utilization is higher, which is in line with the original design intention of green concrete.

[0085] Because lead smelting slag has a slow hydration rate, increasing the lead slag content indirectly reduces the water demand of the cementitious materials. With the water-cement ratio unchanged and the water-reducing agent dosage not altered or reduced, this is equivalent to increasing the water consumption. Therefore, the slump of green pavement concrete with 35% lead smelting slag content tends to be larger than that of concrete with 15% lead slag content. This is more conducive to molding and compaction, thereby reducing voids, increasing density, and improving various performance indicators. Furthermore, because lead smelting slag itself has high hardness and a high Fe content, increasing the lead slag content will correspondingly improve the wear resistance of the concrete test blocks.

[0086] In Example 1 of this invention, the content of solid waste material—lead smelting slag—is increased (to 35% of the total mass of the cementitious material), and an admixture is added (to 0.60% of the total mass of the cementitious material). This results in an optimal green pavement concrete with a slump of 38 mm, meeting actual construction requirements. The 3-day flexural strength is 4.21 MPa, and the 28-day strength is 7.15 MPa, far exceeding the design requirements for flexural strength of medium and light load pavements. The 3-day compressive strength is 41.5 MPa, and the 28-day strength is 58.4 MPa, meeting the strength requirements of C50 concrete. The abrasion resistance is 3.840 kg / m³. 3 It meets the wear requirements for surface concrete of Class III and IV highways.

[0087] Comparative Example 1

[0088] Same as Example 1, except that 157.5 kg of lead smelting slag powder is used, that is, the amount of lead smelting slag powder in the cementitious material is 45%.

[0089] The results showed that the slump of the concrete prepared according to this comparative method was 45 mm, which exceeded the actual construction requirements; the 3-day flexural strength was 3.77 MPa and the 28-day strength was 6.23 MPa, slightly exceeding the design requirements for flexural strength of medium and light load pavements; the 3-day compressive strength was 34.0 MPa and the 28-day strength was 49.5 MPa, which did not meet the C50 concrete strength requirements; and the abrasion resistance was 5.420 kg / m³. 3 This does not meet the requirements for wear of concrete surface layers on Class III and IV highways.

[0090] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A lead smelting slag based green pavement concrete, characterized in that, The raw materials include the following quality parts: lead smelting slag powder 52.5-122.5 parts, cement clinker 122.5 parts, mineral powder 84-154 parts, desulfurization gypsum 21 parts, river sand 627-784 parts, crushed stone 1176-1333 parts, and water 126-154 parts; The main particle size of the lead smelting slag micro powder is D 10 = 3.485 μm, D 50 = 28.336 μm, D 90 = 86.281 μm; The preparation method of the lead smelting slag-based green pavement concrete includes the following steps: The lead smelting slag powder, the cement clinker, the mineral powder, the desulfurization gypsum, the river sand, the crushed stone, the water, and the additive are weighed according to the quality parts, the river sand and the crushed stone are put into a wet stirring machine and stirred for 60 s, then the lead smelting slag powder, the cement clinker, the mineral powder, and the desulfurization gypsum are added, the water is added while stirring, the remaining water mixed with the additive is added into the mixture after stirring for 60 s, and stirring is performed for 60 s, and then the mixture is put into a mold, vibrated, cemented and solidified, demolded, and standard cured to obtain the lead smelting slag-based green pavement concrete.

2. The lead smelting slag-based green pavement concrete according to claim 1, characterized in that, The raw materials further include an additive, and the additive is added in an amount of 0.35-0.60% of the total mass of the cementitious materials.

3. The lead smelting slag based green pavement concrete according to claim 1, characterized in that, The additive is a polycarboxylic acid superplasticizer mother liquor with a solid content of 40%.

4. The lead smelting slag-based green pavement concrete according to any one of claims 1 - 3, characterized in that, The cement clinker has a specific surface area of 365 m 2 / kg, a main particle size of D 10 = 2.637 μm, a D 50 = 22.453 μm, and a D 90 = 83.712 μm.

5. The lead smelting slag-based green pavement concrete according to any one of claims 1 - 3, characterized in that, The main particle size of the ore powder is D 10 = 2.037 pm, D 50 = 9.742 pm, D 90 = 26.027 pm.

6. The lead smelting slag-based green pavement concrete according to any one of claims 1-3, characterized in that, The fineness modulus of the river sand is 2.

57.

7. The lead smelting slag-based green pavement concrete according to any one of claims 1 - 3, characterized in that, The crushed stone is continuously graded, and the particle size is 4.75-19.0 mm.

8. A method for the production of a lead smelting slag based green pavement concrete according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: The lead smelting slag powder, the cement clinker, the mineral powder, the desulfurization gypsum, the river sand, the crushed stone, the water, and the additive are weighed according to the quality parts, the river sand and the crushed stone are put into a wet stirring machine and stirred for 60 s, then the lead smelting slag powder, the cement clinker, the mineral powder, and the desulfurization gypsum are added, the water is added while stirring, the remaining water mixed with the additive is added into the mixture after stirring for 60 s, and stirring is performed for 60 s, and then the mixture is put into a mold, vibrated, cemented and solidified, demolded, and standard cured to obtain the lead smelting slag-based green pavement concrete.

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