High-performance conductive pervious concrete and preparation method thereof

Abstract

The invention relates to the technical field of cement-based building materials, belongs to low-carbon materials, and particularly relates to high-performance conductive pervious concrete and a preparation method thereof.The high-performance conductive pervious concrete is prepared by adopting cement, high-carbon-content fly ash and mineral powder as cementing materials, preparing conductive coarse aggregate through industrial solid waste granulation, and matching with iron tailing sand as fine aggregate; the carbon fiber is added as a conductive phase material to prepare the high-performance conductive permeable concrete with excellent mechanical properties, good conductive effect and high permeable rate, and the conductive permeable concrete can be used for rapid snow melting and deicing of sponge city sidewalks and rapid infiltration, and has good environmental benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of cement-based building materials, belonging to low-carbon materials, and in particular to a high-performance conductive permeable concrete and a preparation method thereof. Background Art

[0002] The construction of sponge cities gives full play to the functions of ecosystems such as roads, green spaces, and water systems in absorbing, infiltrating, and slowly releasing rainwater, effectively controlling urban rainwater runoff, and elastically digesting the problems brought by rainwater. As one of the important materials in the construction of sponge cities, permeable concrete with its unique permeable performance and environmental protection advantages plays a crucial role, fully enhancing the city's ability to respond to natural disasters, and is often used in urban roads, pedestrian walkways, garden landscapes, ecological slopes and other occasions, effectively reducing urban waterlogging.

[0003] The main raw materials of permeable concrete are constructed by mixing aggregate, cement, water, etc. Its characteristic lies in having a continuous pore structure, which can enable surface water to quickly infiltrate into the ground. However, when encountering ice and snow weather, permeable concrete loses its function of quickly draining water. Conductive concrete is a special kind of concrete, which becomes a conductor with certain conductivity by adding appropriate conductive phase materials to ordinary concrete, so as to realize functions such as deicing and snow melting on the road surface. The commonly used conductive phase materials can be classified into different types according to their materials and shapes. Classified by shape, the conductive phase materials in the prior art can be divided into fiber types such as carbon fiber and steel fiber, particle types such as conductive aggregate, and conductive powder types such as graphite, graphene, carbon black, etc.

[0004] However, there are few literatures in the prior art to solve the problem of deicing and snow melting of permeable concrete. Moreover, although adding fibers to permeable concrete can improve its strength, it is easy to cause blockage of permeable pores and affect the permeable performance. How to meet the mechanical properties, conductive properties and permeable properties of permeable concrete with conductive aggregate and conductive powder has not been solved either. Summary of the Invention

[0005] To solve the problems existing in the prior art, the present invention provides a high-performance conductive permeable concrete, which uses cement, high-carbon fly ash, and mineral powder as cementitious materials, prepares conductive coarse aggregate by granulating industrial solid waste, uses iron tailings sand as fine aggregate, and adds carbon fiber as a conductive phase material to prepare a high-performance conductive permeable concrete with excellent mechanical properties, good conductive effect, and high permeability. It can be used for rapid deicing and snow melting on the sidewalks of sponge cities and quickly infiltrate, and has good environmental benefits.

[0006] Specifically, the high-performance conductive permeable concrete of the present invention is composed of the following raw materials in parts by weight:

[0007] Cement 190 - 210 parts,

[0008] 140 - 150 parts of high-carbon fly ash,

[0009] 50 - 60 parts of mineral powder,

[0010] 1600 - 1680 parts of conductive coarse aggregate,

[0011] 290 - 310 parts of iron tailings sand,

[0012] 0.3 - 0.4 parts of chopped carbon fiber,

[0013] 4 - 5 parts of water reducing agent,

[0014] 120 - 125 parts of water.

[0015] Fly ash is a product of thermal power generation in coal-fired power plants. High-quality fly ash is commonly used as a concrete admixture to replace part of the cement and reduce the production cost of concrete. The national standard GB / T1596 classifies fly ash used for mixing mortar and concrete into three grades. Among them, grade I and grade II fly ash are the most commonly used fly ash varieties, with relatively appropriate water demand ratio, high activity, and relatively small loss on ignition. However, for high-carbon fly ash with a loss on ignition exceeding 10%, firstly, it has exceeded the standard of grade III fly ash, and the high carbon content means a serious impact on the workability and mechanical properties of concrete, often resulting in problems such as large slump loss of concrete and easy floating of black slurry. Therefore, it is difficult to be applied in actual production. According to the characteristics of the preparation process of permeable concrete and combined with the need for electrical conductivity, the present invention adds high-carbon fly ash to replace cement as a cementitious material, utilizes its reduction of slurry fluidity and high-carbon characteristics to make the cement-based slurry have better coating performance and electrical conductivity effect, and builds an electrical conduction path between carbon fiber and conductive coarse aggregate. Cooperating with cement and mineral powder as cementitious materials together can greatly improve the reuse rate of high-carbon fly ash.

[0016] Preferably, the preparation process of the conductive coarse aggregate is as follows: Mix red mud, fine slag of coal gasification, ultrafine steel slag powder, desulfurized gypsum, fly ash beads, and water in a mass ratio of (2 - 2.2):(7.8 - 8):(3 - 4):(1 - 1.6):(1 - 1.2):(5.6 - 6), granulate, carry out autoclave curing, and screen to obtain.

[0017] Permeable concrete has a large number of interconnected pores. Its aggregate and cementitious material slurry are bonded and embedded to form a supporting skeleton to generate mechanical strength. To achieve a conductive effect, the bonding between the aggregate and the cementitious material must form a good conductive path. Therefore, through a large number of experimental studies, the present invention uses red mud, fine slag from coal gasification, ultrafine steel slag powder, desulfurized gypsum, and fly ash microspheres as the main raw materials to granulate and prepare conductive coarse aggregate with good conductive effect. Fine slag from coal gasification is the waste residue generated in the coal gasification process. The silicon-aluminum substances it contains have a certain degree of hydration activity, but due to its high carbon content, its recycling and utilization are limited. The present invention uses fine slag from coal gasification as the main raw material, supplemented with ultrafine steel slag powder and fly ash microspheres to supplement active substances, and uses red mud and desulfurized gypsum for activation. After granulation and autoclave curing, conductive coarse aggregate with high strength performance is prepared, and iron tailings sand with a certain conductive effect is used together as the aggregate to jointly construct a conductive path with the cementitious material slurry to achieve the high conductive performance of permeable concrete, so that it can be electrified to melt snow and remove ice in snowy weather.

[0018] Preferably, the cement is at least one of portland cement and ordinary portland cement.

[0019] Preferably, the chemical composition of the high-carbon fly ash is: SiO2 40-43%, Al2O3 20-26%, Fe2O3 11-14%, CaO 2-4%, loss on ignition 13-18%, and the remaining impurities are the balance.

[0020] Preferably, the mineral powder is at least one of S95 grade and S105 grade.

[0021] Preferably, the red mud is Bayer red mud.

[0022] Preferably, the particle size of the fine slag from coal gasification is ≤5 mm, and its chemical composition is: SiO2 35.8-38.1%, Al2O3 8.6-10.4%, Fe2O3 8.3-9.8%, CaO 13.9-14.6%, loss on ignition 20.3-22.3%, and the remaining impurities are the balance.

[0023] Preferably, the particle size of the ultrafine steel slag powder is D10 = 1.5-1.7 μm, D50 = 2.8-3.0 μm, D90 = 7.8-8.0 μm, and its chemical composition is: CaO 40-43%, SiO2 30-32%, Al2O3 9-11%, MgO 3.5-4.2%, Fe2O3 3-3.5%, and the remaining impurities are the balance.

[0024] Preferably, the autoclave curing pressure is 800-1100 kPa, the temperature is 170-185 °C, and the time is 10-15 h.

[0025] Preferably, the particle size of the conductive coarse aggregate is 5-10 mm.

[0026] Preferably, the particle size of the iron tailings sand is 1 - 4.25 mm.

[0027] Preferably, the diameter of the chopped carbon fiber is 5 - 10 μm and the length is 1 - 2 mm.

[0028] The permeable concrete is different from the dense structure of ordinary concrete and has a large number of connected pores. Therefore, there are congenital defects in the conductive path. To improve the conductive effect of the permeable concrete without affecting its water permeability, a small amount of chopped carbon fiber is added in the present invention, which can be compounded with the cementitious material slurry to form a good conductive path of cementitious material - fiber - conductive aggregate.

[0029] Preferably, the water reducing agent is a naphthalene - based water reducing agent. Ordinary polycarboxylate water reducing agents are easily adsorbed by carbon particles. Therefore, the naphthalene - based water reducing agent is preferentially used in the present invention. Of course, using a polycarboxylate water reducing agent with high adaptability or a polycarboxylate water reducing agent compounded with a sacrificial agent can ensure the water reducing effect and is also within the protection scope of the present invention.

[0030] The present invention also relates to a preparation method of the above - mentioned high - performance conductive permeable concrete. Specifically, it includes the following steps:

[0031] 1) Weigh each raw material according to parts by weight.

[0032] 2) Mix cement, high - carbon - content fly ash, mineral powder, and chopped carbon fiber evenly to obtain dry materials.

[0033] 3) Take a small amount of water and mix it with the conductive coarse aggregate to wet it, then add the iron tailings sand and mix evenly to obtain aggregates.

[0034] 4) Mix the water reducing agent with the remaining water evenly to obtain liquid materials.

[0035] 5) Add the dry materials into the aggregates, mix evenly, add the liquid materials, mix evenly, and form to obtain the product.

[0036] The present invention has the following technical advantages:

[0037] 1. The present invention uses high - carbon - content fly ash to increase the viscosity of the slurry, thereby having an excellent coating effect, promoting the formation of effective conductive paths and permeable pores, and realizing the reuse of high - carbon - content fly ash.

[0038] 2. The present invention prepares conductive coarse aggregates, which cooperate with high - carbon - content fly ash, carbon fiber, and iron tailings sand to form a good conductive path and ensure the conductive effect.

[0039] 3. The present invention utilizes a large amount of industrial solid wastes and has good economic and ecological benefits. Detailed implementation mode

[0040] To characterize the technical effects of the present invention, concrete was prepared and its properties were tested. During the resistivity test, the four-electrode method was used, the voltage was 32 V, the specimen size was 150×150×300 mm, and it was cured under standard conditions for 28 days. During the test, P·O 42.5 cement was used for cement, Bayer process red mud was used for red mud, the chemical composition of high-carbon fly ash was: SiO2 42.3%, Al2O3 22.9%, Fe2O3 13.6%, CaO 2.5%, loss on ignition 15.5%, and the balance was other impurities. The particle size of the coal gasification fine slag was ≤5 mm, and its chemical composition was: SiO2 37.1%, Al2O3 9.1%, Fe2O3 8.9%, CaO 14.0%, loss on ignition 21.5%, and the balance was other impurities. The particle size of the ultra-fine steel slag powder was D10 = 1.6 μm, D50 = 2.9 μm, D90 = 7.9 μm, and its chemical composition was: CaO 42.0%, SiO2 31.1%, Al2O3 9.8%, MgO 3.6%, Fe2O3 3.2%, and the balance was other impurities. The particle size of the conductive coarse aggregate was 5 - 10 mm, the particle size of the iron tailing sand was 1 - 4.25 mm, and the diameter of the chopped carbon fiber was 5 - 10 μm and the length was 1 - 2 mm.

[0041] Example 1

[0042] The concrete was composed of the following raw materials in parts by weight: 210 parts of cement, 140 parts of high-carbon fly ash, 60 parts of S95-grade mineral powder, 1630 parts of conductive coarse aggregate, 300 parts of iron tailing sand, 0.3 part of chopped carbon fiber, 4.5 parts of naphthalene-based water reducer, and 124 parts of water.

[0043] The preparation process of the conductive coarse aggregate was as follows: red mud, coal gasification fine slag, ultra-fine steel slag powder, desulfurized gypsum, fly ash cenosphere, and water were mixed and granulated according to a mass ratio of 2:7.8:3.5:1.2:1.2:5.8, and then autoclaved and cured at a pressure of 1000 kPa and a temperature of 180 °C for 12 h, and then sieved to obtain it.

[0044] After testing, the 28-day compressive strength of the concrete was 36.8 MPa, the resistivity was 8.2 Ω·m, and the water permeability coefficient was 10.2 mm / s.

[0045] Example 2

[0046] The concrete was composed of the following raw materials in parts by weight: 200 parts of cement, 150 parts of high-carbon fly ash, 55 parts of S95-grade mineral powder, 1650 parts of conductive coarse aggregate, 290 parts of iron tailing sand, 0.4 part of chopped carbon fiber, 5 parts of naphthalene-based water reducer, and 124 parts of water.

[0047] The preparation process of the conductive coarse aggregate is as follows: Mix red mud, fine slag from coal gasification, ultrafine steel slag powder, desulfurized gypsum, fly ash microspheres, and water in a mass ratio of 2.2:8:3:1:1.1:5.8, granulate them, and perform autoclave curing at a pressure of 1000 kPa and a temperature of 180 °C for 12 h, then screen to obtain the product.

[0048] After testing, the 28-day compressive strength of the concrete is 37.3 MPa, the resistivity is 7.9 Ω·m, and the water permeability coefficient is 10.3 mm / s.

[0049] Comparative Example 1

[0050] The concrete is composed of the following raw materials in parts by weight: 210 parts of cement, 140 parts of Class II fly ash, 60 parts of S95-grade mineral powder, 1630 parts of conductive coarse aggregate, 300 parts of iron tailing sand, 0.3 parts of short-cut carbon fiber, 4.5 parts of naphthalene-based water reducer, and 124 parts of water.

[0051] The preparation process of the conductive coarse aggregate is as follows: Mix red mud, fine slag from coal gasification, ultrafine steel slag powder, desulfurized gypsum, fly ash microspheres, and water in a mass ratio of 2:7.8:3.5:1.2:1.2:5.8, granulate them, and perform autoclave curing at a pressure of 1000 kPa and a temperature of 180 °C for 12 h, then screen to obtain the product.

[0052] After testing, the 28-day compressive strength of the concrete is 39.6 MPa, the resistivity is 46.0 Ω·m, and the water permeability coefficient is 3.1 mm / s.

[0053] Comparative Example 2

[0054] The concrete is composed of the following raw materials in parts by weight: 210 parts of cement, 140 parts of high-carbon fly ash, 60 parts of S95-grade mineral powder, 1630 parts of 5-10 mm iron tailing ore, 300 parts of iron tailing sand, 0.3 parts of short-cut carbon fiber, 4.5 parts of naphthalene-based water reducer, and 124 parts of water.

[0055] After testing, the 28-day compressive strength of the concrete is 37.2 MPa, the resistivity is 126.4 Ω·m, and the water permeability coefficient is 7.7 mm / s.

[0056] Comparative Example 3

[0057] The concrete is composed of the following raw materials in parts by weight: 210 parts of cement, 140 parts of high-carbon fly ash, 60 parts of S95-grade mineral powder, 1630 parts of conductive coarse aggregate, 300 parts of iron tailing sand, 0.3 parts of short-cut carbon fiber, 4.5 parts of naphthalene-based water reducer, and 124 parts of water.

[0058] The preparation process of the conductive coarse aggregate is as follows: Mix red mud, mineral powder, steel slag powder, desulfurized gypsum, fly ash microspheres, and water in a mass ratio of 2:7.8:3.5:1.2:1.2:5.8 for granulation, and perform autoclave curing at a pressure of 1000 kPa and a temperature of 180 °C for 12 h, then screen to obtain it.

[0059] After testing, the 28-day compressive strength of the concrete is 35.9 MPa, the resistivity is 456.4 Ω·m, and the water permeability coefficient is 9.1 mm / s.

[0060] Comparative Example 4

[0061] The concrete is composed of the following raw materials in parts by weight: 210 parts of cement, 140 parts of high-carbon fly ash, 60 parts of S95-grade mineral powder, 1630 parts of conductive coarse aggregate, 300 parts of iron tailings sand, 0.3 part of short-cut carbon fiber, 4.5 parts of naphthalene-based water reducer, and 124 parts of water.

[0062] The preparation process of the conductive coarse aggregate is as follows: Mix red mud, fine slag from coal gasification, steel slag powder, desulfurized gypsum, fly ash, and water in a mass ratio of 2:7.8:3.5:1.2:1.2:5.8 for granulation, and perform autoclave curing at a pressure of 1000 kPa and a temperature of 180 °C for 12 h, then screen to obtain it.

[0063] After testing, the 28-day compressive strength of the concrete is 28.3 MPa, the resistivity is 34.6 Ω·m, and the water permeability coefficient is 9.3 mm / s.

[0064] Comparative Example 5

[0065] The concrete is composed of the following raw materials in parts by weight: 210 parts of cement, 140 parts of high-carbon fly ash, 60 parts of S95-grade mineral powder, 1930 parts of conductive coarse aggregate, 4.5 parts of naphthalene-based water reducer, and 124 parts of water.

[0066] The preparation process of the conductive coarse aggregate is as follows: Mix red mud, fine slag from coal gasification, ultra-fine steel slag powder, desulfurized gypsum, fly ash microspheres, and water in a mass ratio of 2:7.8:3.5:1.2:1.2:5.8 for granulation, and perform autoclave curing at a pressure of 1000 kPa and a temperature of 180 °C for 12 h, then screen to obtain it.

[0067] After testing, the 28-day compressive strength of the concrete is 23.9 MPa, the resistivity is 680.1 Ω·m, and the water permeability coefficient is 4.6 mm / s.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A high-performance conductive and permeable concrete, characterized in that, It consists of the following raw materials by weight parts: 190 - 210 parts of cement, 140 - 150 parts of high carbon content fly ash, 50 - 60 parts of mineral powder, 1600 - 1680 parts of conductive coarse aggregate, 290 - 310 parts of iron tailings sand, 0.3 - 0.4 parts of chopped carbon fiber, 4 - 5 parts of water reducing agent, 120 - 125 parts of water, The preparation process of the conductive coarse aggregate is as follows: Mix red mud, fine slag from coal gasification, superfine steel slag powder, desulfurized gypsum, fly ash cenosphere, and water according to the mass ratio of (2 - 2.2):(7.8 - 8):(3 - 4):(1 - 1.6):(1 - 1.2):(5.6 - 6), granulate, perform autoclave curing, and screen to obtain it.

2. The high-performance conductive permeable concrete according to claim 1, wherein The cement is at least one of portland cement and ordinary portland cement.

3. The high-performance conductive permeable concrete according to claim 1, characterized in that, The chemical composition of the high carbon content fly ash is: SiO₂ 40 - 43%, Al₂O₃ 20 - 26%, Fe₂O₃ 11 - 14%, CaO 2 - 4%, loss on ignition 13 - 18%, and the remaining impurities are the balance.

4. The high-performance conductive permeable concrete according to claim 1, wherein The mineral powder is at least one of S95 grade and S105 grade.

5. The high-performance conductive permeable concrete according to claim 1, wherein The red mud is Bayer process red mud.

6. The high-performance conductive permeable concrete according to claim 1, wherein The particle size of the fine slag from coal gasification is ≤5mm, and its chemical composition is: SiO₂ 35.8 - 38.1%, Al₂O₃ 8.6 - 10.4%, Fe₂O₃ 8.3 - 9.8%, CaO 13.9 - 14.6%, loss on ignition 20.3 - 22.3%, and the remaining impurities are the balance.

7. The high-performance conductive permeable concrete according to claim 1, wherein The particle size of the superfine steel slag powder: D10 is 1.5 - 1.7μm, D50 is 2.8 - 3.0μm, D90 is 7.8 - 8.0μm, and its chemical composition is: CaO 40 - 43%, SiO₂ 30 - 32%, Al₂O₃ 9 - 11%, MgO 3.5 - 4.2%, Fe₂O₃ 3 - 3.5%, and the remaining impurities are the balance.

8. The high-performance conductive permeable concrete according to claim 1, wherein The particle size of the conductive coarse aggregate is 5 - 10mm, and the particle size of the iron tailings sand is 1 - 4.25mm.

9. The high-performance conductive permeable concrete according to claim 1, wherein, The diameter of the chopped carbon fiber is 5 - 10μm, and the length is 1 - 2mm.

10. The preparation method of the high-performance conductive permeable concrete according to any one of claims 1-9, characterized in that, It includes the following steps: 1) Weigh each raw material by weight parts, 2) Mix the cement, high carbon content fly ash, mineral powder, and chopped carbon fiber evenly to obtain dry materials, 3) Take a small amount of water to mix and moisten with the conductive coarse aggregate, add the iron tailings sand and mix evenly to obtain aggregates, 4) Mix the water reducing agent and the remaining water evenly to obtain liquid materials, 5) Add the dry materials into the aggregates, mix evenly, add the liquid materials, mix evenly, and form to obtain the product.