A conductive, non-fired artificial aggregate and its preparation and application methods

Abstract

This invention belongs to the field of building materials technology, specifically relating to a conductive, non-fired artificial aggregate and its preparation and application methods. The non-fired artificial aggregate comprises the following components by mass: 60-75 parts of industrial solid waste substrate, 12-20 parts of composite conductive filler, 10-18 parts of modified inorganic binder, 2-5 parts of functional additives, and 7-11 parts of water. The industrial solid waste substrate is a mixture of steel slag and slag powder; the composite conductive filler is a composite of graphene-modified graphite powder and nickel-plated carbon fiber; the modified inorganic binder is a mixture of sulfoaluminate cement, metakaolin, and sodium silicate; and the functional additives are a composite of polycarboxylate superplasticizer and nano-calcium carbonate. The advantages of this invention are: the non-fired artificial aggregate possesses both high conductivity and high strength, and can be directly used as a concrete filler without the need for additional conductive materials; the conductive non-fired artificial aggregate serves as a built-in sensing unit, forming a distributed monitoring network whose monitoring range can cover the entire concrete structure.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of building materials, and particularly relates to a fired-free artificial aggregate with electrical conductivity and a preparation and application method thereof. BACKGROUND

[0002] A concrete structure is a core carrier in the field of building engineering, and its long-term health state directly determines the engineering safety and service life. At present, the monitoring of a concrete structure mainly relies on external sensors, but such a technology has obvious limitations.

[0003] An external sensor can only collect data in a local area, and for a large concrete structure, a "monitoring blind area" is easily formed, and the overall health state of the structure cannot be reflected.

[0004] High installation and maintenance cost: the sensor needs to be pre-buried or pasted later, and the installation process is complex. Moreover, the sensor is exposed to the outdoor environment for a long time, is easily eroded by rainwater, and is affected by temperature changes and fails. The maintenance cost accounts for 40-60% of the total cost of the monitoring system.

[0005] Single function of aggregate: the traditional artificial aggregate is only used as a filling material for concrete and does not have functional properties. If the electrical conductivity monitoring function is to be realized, an electrically conductive material needs to be added to the concrete, which not only easily leads to a decrease in the mechanical strength of the concrete but also increases the cost of raw materials.

[0006] High energy consumption in aggregate production: the existing artificial aggregate with electrical conductivity mostly uses a high-temperature sintering process, and the unit energy consumption is greater than or equal to 600 kWh / t, which does not meet the low-carbon and environmentally friendly production requirements. Moreover, the electrically conductive filler is easily oxidized during the sintering process, resulting in poor stability of the electrical conductivity.

[0007] Therefore, it is a key direction to develop a fired-free artificial aggregate with electrical conductivity and high strength, which can be directly used as an "internal sensing unit" of concrete, and to match it with an efficient intelligent monitoring system, so as to break through the technical bottleneck of the monitoring of a concrete structure. SUMMARY

[0008] The purpose of the present application is to provide a fired-free artificial aggregate with electrical conductivity and a preparation and application method thereof according to the deficiencies of the prior art. The fired-free artificial aggregate is prepared by using an industrial solid waste base material as a skeleton main body, constructing a three-dimensional conductive network by using graphene modified graphite powder and nickel-plated carbon fibers to endow the aggregate with electrical conductivity, and using a modified inorganic binder to glue the loose material into a solid whole under pressure under the condition of firing-free. Moreover, the functional additives can effectively disperse the composite conductive filler to make it uniformly distributed in the slurry.

[0009] The purpose of the present application is achieved by the following technical solutions:

[0010] The application discloses a kind of electrically conductive non-fired artificial aggregate, comprising the following mass components: industrial solid waste base material 60-75 parts, composite conductive filler 12-20 parts, modified inorganic binder 10-18 parts, functional additives 2-5 parts, water 7-11 parts;

[0011] The industrial solid waste base material is a mixture of steel slag and slag powder in a mass ratio of 2:1-1.5.

[0012] The composite conductive filler is a mixture of graphene modified graphite powder and nickel-coated carbon fiber in a mass ratio of 4:1.

[0013] The modified inorganic binder is a mixture of sulphoaluminate cement, metakaolin and sodium silicate in a mass ratio of 5:3:2.

[0014] The functional additives are a mixture of polycarboxylic acid water reducer and nano calcium carbonate in a mass ratio of 3:1.

[0015] The non-fired artificial aggregate comprises the following mass components: industrial solid waste base material 60 parts, composite conductive filler 20 parts, modified inorganic binder 18 parts, functional additives 5 parts, and water 11 parts.

[0016] The industrial solid waste base material is a mixture of steel slag and slag powder in a mass ratio of 2:1.

[0017] The composite conductive filler is a mixture of graphene modified graphite powder and nickel-coated carbon fiber in a mass ratio of 4:1.

[0018] The modified inorganic binder is a mixture of sulphoaluminate cement, metakaolin and sodium silicate in a mass ratio of 5:3:2.

[0019] The functional additives are a mixture of polycarboxylic acid water reducer and nano calcium carbonate in a mass ratio of 3:1.

[0020] A method for preparing the electrically conductive non-fired artificial aggregate, comprising the following steps:

[0021] S1: placing the industrial solid waste base material in a drying oven and drying it at 105-110°C for 2-3 hours to reduce the water content to less than or equal to 0.8%, and then cooling and storing it;

[0022] S2: adding the composite conductive filler and polycarboxylic acid water reducer in the functional additives to deionized water, stirring at a stirring rate of 800-1200 r / min for 15-20 minutes to form a uniform conductive slurry;

[0023] S3: adding the pretreated industrial solid waste base material, modified inorganic binder and nano calcium carbonate in the functional additives to the conductive slurry, adjusting the stirring rate to 1500-2000 r / min, and stirring for 25-35 minutes to obtain a plastic aggregate mixture.

[0024] S4: The plasticity aggregate mixture is put into a hydraulic forming machine, and is formed under the conditions of a forming pressure of 18-25 MPa and a pressure maintaining time of 4-6 minutes, to obtain a cylindrical aggregate green body with a diameter of 15 mm;

[0025] S5: The aggregate green body is placed in a curing chamber, and is cured under the conditions of a temperature of 25-30 DEG C and a humidity of greater than or equal to 90% for 4 days, then is cured under the conditions of a temperature of 50-60 DEG C and a humidity of greater than or equal to 85% for 3 days, and finally is naturally cooled to room temperature, to obtain the sinter-free artificial aggregate product with conductivity.

[0026] The natural cooling rate in step S5 is 2-3 DEG C / h.

[0027] The preparation method of the graphene modified graphite powder in the composite conductive filler comprises the following steps: mixing graphite powder and a graphene dispersion liquid at a mass ratio of 10:1, ultrasonic dispersion for 20-30 minutes under an ultrasonic power of 300-500 W, and drying to obtain the graphene modified graphite powder; and the mass concentration of the graphene dispersion liquid is 0.5%.

[0028] An application method of any of the sinter-free artificial aggregate products with conductivity, characterized in that the application method comprises the following steps:

[0029] (S1) The sinter-free artificial aggregate is pre-embedded in the concrete in a rectangular array mode, the distance between adjacent sinter-free artificial aggregates is 20-50 cm, a copper lead electrode is pre-set on the surface of the sinter-free artificial aggregate, the copper lead electrode is connected to an electric parameter acquisition unit outside the concrete through a shielding wire, the electric parameter acquisition unit is connected to an intelligent analysis unit through a data transmission unit, and the intelligent analysis unit is connected to a terminal display unit;

[0030] (S2) The electric parameter acquisition unit measures the electric impedance value between the sinter-free artificial aggregates in real time by using an impedance analyzer; the electric parameter acquisition unit transmits the collected data to the intelligent analysis unit through the data transmission unit for analysis and judgment, the electric impedance threshold range under the normal state of the concrete is pre-set, and whether the concrete has cracks, abnormal humidity or stress damage is judged by comparing the deviation of the real-time electric impedance value and the threshold range.

[0031] The application has the following advantages:

[0032] (1) The sinter-free artificial aggregate product with conductivity is used as a built-in sensing unit to form a distributed monitoring network, the monitoring range can cover the whole structure of the concrete, there is no monitoring blind area, and the monitoring coverage rate is improved by 80-100% compared with the traditional external sensor monitoring;

[0033] (2) The baking-free artificial aggregate has high conductivity and high strength, can be directly used as a concrete filler, does not need to add an electrically conductive material, and avoids negative effects on the mechanical properties of the concrete;

[0034] (3) The baking-free process saves the high-temperature sintering link, reduces the unit energy consumption to 150-200 kWh / t, saves energy by 70-80% compared with the traditional sintering process, and has an industrial solid waste content of 60-75%, realizes solid waste resource utilization, and reduces environmental pollution;

[0035] (4) The integrated functions of data collection, intelligent analysis, abnormal early warning and wireless transmission are integrated, the damage identification accuracy is high, the response speed is fast, the efficiency is 50-100 times higher than that of manual inspection, and the monitoring and maintenance cost is greatly reduced;

[0036] (5) The resistance fluctuation of the baking-free artificial aggregate is less than or equal to ±8% in the temperature range of-30 DEG C to 70 DEG C, the sealed electrode design can resist the erosion of rain, humidity and other harsh environments, the service life is greater than or equal to 10 years, and the long-term monitoring requirements of the concrete structure are met. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a preparation flowchart of the baking-free artificial aggregate in the application;

[0038] Figure 2 It is a schematic diagram of the intelligent monitoring concrete system in the application. DETAILED DESCRIPTION

[0039] The features and other related features of the application are further described in detail below by combining the drawings through embodiments, so as to facilitate the understanding of the skilled in the art:

[0040] Embodiment 1: as shown in Figure 1 and 2 , the embodiment specifically relates to a baking-free artificial aggregate with conductivity and a preparation method and application method thereof, and the mass components of the baking-free artificial aggregate are as follows: 65 parts of industrial solid waste base material, 15 parts of composite conductive filler, 15 parts of modified inorganic binder, 3.5 parts of functional additive, and 9 parts of water.

[0041] Among them, the mass components of the industrial solid waste base material are: 43.3 parts of steel slag and 21.7 parts of slag powder.

[0042] The mass components of the composite conductive filler are: 12 parts of graphene modified graphite powder and 3 parts of nickel-plated carbon fiber.

[0043] The mass components of the modified inorganic binder are: 7.5 parts of sulphoaluminate cement, 4.5 parts of metakaolin, and 3 parts of sodium silicate.

[0044] The quality components of the functional aid are: polycarboxylic acid water reducing agent 2.6 parts, nano calcium carbonate 0.9 parts.

[0045] The functional principles of each component material are explained as follows:

[0046] The industrial solid waste base material takes steel slag and slag as the main component of aggregate, which can effectively reduce the cost of raw materials. Steel slag and slag powder are both industrial waste residues with potential activity. They can undergo alkali-activation reaction in the alkaline environment provided by modified inorganic binder (especially sodium silicate therein), generating gel products such as hydrated calcium silicate (C-S-H), thereby providing and continuously increasing strength.

[0047] The graphene modified graphite powder and nickel-coated carbon fiber in the composite conductive filler can build a stable and efficient three-dimensional conductive network, giving the aggregate conductive function. Graphene has extremely high electrical conductivity and huge specific surface area, which can play the role of "bridging" and "wire" between graphite powder particles, effectively filling the gaps in the conductive path and significantly reducing the resistivity of the entire composite material. Carbon fiber has a high aspect ratio and can overlap each other in the matrix to form a "linear" conductive path. The nickel metal layer improves the wettability and bonding force of the hydrophobic carbon fiber and the inorganic binder hydration product, reducing the interface defects. Metal nickel is an excellent conductor, which is wrapped on the surface of carbon fiber, further enhancing the electrical conductivity of the fiber itself and the contact effect with the surrounding conductive filler.

[0048] In the modified inorganic binder, sulphoaluminate cement provides early strength. Its hydration speed is fast, which can make the aggregate shape and have certain handling strength in a short time, improving the production efficiency. Sodium silicate (water glass) as an alkali activator and binding component, it provides a strong alkaline environment to activate the activity of steel slag, slag powder and metakaolin, and promotes them to react to generate cementitious materials. Sodium silicate itself can also produce adhesion by dehydrating and hardening. Metakaolin is a high-efficiency pozzolanic material that can quickly react with alkali conditions to generate a large amount of C-S-H gel, greatly contributing to the growth of late strength, and refining the pore structure, making the aggregate more dense.

[0049] In the functional aid, polycarboxylic acid water reducing agent can play a dispersing and water-reducing effect. That is, the high molecular chain structure of polycarboxylic acid water reducing agent produces a strong steric hindrance effect and electrostatic repulsion on the particle surface, which can effectively disperse the conductive filler (especially graphene and graphite powder, which are prone to agglomeration) and solid waste particles, making them uniformly distributed in the slurry. On the premise of ensuring the same fluidity, the water consumption during mixing is significantly reduced, thereby reducing the water-binder ratio, making the aggregate after shaping have lower porosity, more dense structure and higher strength. Nano calcium carbonate can play the role of crystal nucleus, filling effect and interface improvement.

[0050] For example, Figure 1As shown, the preparation method of the conductive non-fired artificial aggregate in this embodiment includes the following steps:

[0051] S1. The steel slag and slag powder constituting the industrial solid waste substrate were placed together in a drying oven and dried at a temperature of 108°C for 2.5 hours. After drying, the water content was detected to be reduced to 0.6%, and then the sample was taken out and cooled to room temperature for standby.

[0052] S2. The graphene modified graphite powder and nickel-coated carbon fiber in the composite conductive filler, and the polycarboxylate superplasticizer in the functional additive were added to 9 parts of deionized water. The stirring rate of the stirring equipment was set to 1000 r / min, and the stirring was continued at this rate for 18 minutes to form a uniformly dispersed conductive slurry.

[0053] S3. The industrial solid waste substrate pretreated in step S1, and the sulphoaluminate cement, metakaolin, sodium silicate in the modified inorganic binder, and the nano calcium carbonate in the functional additive were added to the conductive slurry prepared in step S2. The stirring rate of the stirring equipment was increased to 1800 r / min, and the stirring was continued at this rate for 30 minutes to obtain an aggregate mixture with good plasticity.

[0054] S4. The aggregate mixture obtained in step S3 was placed into a hydraulic forming machine. The forming pressure of the hydraulic forming machine was set to 22 MPa, and the pressure holding time was set to 5 minutes. Under these conditions, the mixture was pressed into a cylindrical green body with a diameter of 15 mm.

[0055] S5. The aggregate green body obtained in step S4 was transferred to a curing chamber. First, it was cured at a temperature of 28°C and a humidity of 92% for 4 days. Then, the temperature of the curing chamber was adjusted to 55°C and the humidity to 88%, and the curing was continued for another 3 days. After curing, the sample was naturally cooled to room temperature at a rate of 2.5°C / h. The final product was a conductive non-fired artificial aggregate. It is worth noting that the natural cooling rate is generally 2-3°C / h to avoid large temperature differences that may cause micro-cracks in the aggregate, affecting the stability of the electrical conductivity.

[0056] The performance of the conductive non-fired artificial aggregate product in this embodiment was tested, and the test results are as follows: the compressive strength is 36 MPa, the volume resistivity is 0.8 Ω·m, the water absorption is 5.8%, and the resistance fluctuation is ±6.2% in the temperature range of -30°C to 70°C. All the performances meet the requirements of concrete structure monitoring.

[0057] As shown in Figure 2 , the application method of the conductive non-fired artificial aggregate in this embodiment includes the following steps:

[0058] (S1) Build an intelligent monitoring concrete system:

[0059] The non-burned artificial aggregate is pre-buried in the C50 concrete in a rectangular array manner, the distance between adjacent non-burned artificial aggregates is 30 cm, a copper lead electrode is pre-set on the surface of the non-burned artificial aggregate, the copper lead electrode is connected with the electric parameter acquisition unit outside the concrete through a shielding wire, in the pre-buried process, the copper lead electrode pre-set on the surface of the non-burned artificial aggregate is connected with the shielding wire firmly, and the connecting point is sealed by using an epoxy resin sealant to avoid short circuit caused by slurry penetration during concrete pouring.

[0060] The electric parameter acquisition unit is connected with the intelligent analysis unit through a data transmission unit, and the intelligent analysis unit is connected with a terminal display unit.

[0061] The electric parameter acquisition unit adopts an impedance analyzer, the collection frequency range is 100 Hz-10 kHz, and the collection accuracy is ±0.1%, and in the embodiment, the collection frequency is set to 1 kHz.

[0062] The intelligent analysis unit is equipped with a PLC controller and a machine learning algorithm module, the preset resistance threshold range of the concrete in a normal state is 800-1200 Ω, the deviation of the real-time resistance value from the threshold value is compared, and it is judged whether the concrete has cracks, humidity abnormalities or stress damage.

[0063] The data transmission unit adopts a wireless communication module, the transmission distance is ≤5 km, the transmission distance is set to 3 km in the embodiment, the data transmission rate is ≥1 kbps, and the breakpoint transmission is supported.

[0064] The terminal display unit includes a touch display screen and a cloud platform, can display the resistance curve and the concrete health state evaluation result in real time, and supports historical data query and abnormal alarm.

[0065] (S2) The electric parameter acquisition unit measures the resistance value between the non-burned artificial aggregates in real time by using the impedance analyzer; the electric parameter acquisition unit transmits the collected data to the intelligent analysis unit through the data transmission unit for analysis and judgment, the preset resistance threshold range of the concrete in a normal state is 800-1200 Ω, the deviation of the real-time resistance value from the threshold range is compared, and it is judged whether the concrete has cracks, humidity abnormalities or stress damage.

[0066] The damage simulation test is conducted on the built intelligent monitoring concrete system, and the test results are as follows:

[0067] (1) a linear crack with a width of 0.2 mm is cut on the surface of the concrete test block, the system monitors that the resistance between the non-burned artificial aggregates rises from 1000 Ω to 1250 Ω in real time, triggers the sound and light alarm within 10 s, pushes the "crack damage" early warning information to the terminal display unit, and the damage identification accuracy is 100%.

[0068] (2) Spray water continuously onto the surface of the concrete test block to raise the internal humidity of the test block to over 95%. The system detects that the impedance drops from 1000Ω to 820Ω and triggers an alarm within 8 seconds, pushing out a "humidity abnormality" warning message. The recognition accuracy rate is 100%.

[0069] (3) When a pressure of 20MPa is applied to the concrete test block by a pressure testing machine, the system monitors the impedance fluctuating from 1000Ω to 1080Ω, triggers an alarm within 12s, and pushes the "stress damage" warning information. The recognition accuracy rate is 90%.

[0070] Example 2: This example specifically relates to a conductive non-fired artificial aggregate and its preparation and application methods. The mass composition of the non-fired artificial aggregate is as follows: 75 parts of industrial solid waste substrate, 12 parts of composite conductive filler, 10 parts of modified inorganic binder, 2 parts of functional additives, and 7 parts of water.

[0071] The industrial solid waste substrate consists of the following components: 50 parts steel slag and 25 parts slag powder.

[0072] The mass composition of the composite conductive filler is: 9.6 parts of graphene-modified graphite powder and 2.4 parts of nickel-plated carbon fiber.

[0073] The modified inorganic binder consists of the following components: 5 parts sulfoaluminate cement, 3 parts metakaolin, and 2 parts sodium silicate.

[0074] The functional additives consist of: 1.5 parts polycarboxylate superplasticizer and 0.5 parts nano-calcium carbonate.

[0075] like Figure 1 As shown, the method for preparing conductive, non-fired artificial aggregate in this embodiment includes the following steps:

[0076] S1. Place the steel slag and slag powder in a drying oven and dry them at 105℃ for 3 hours. After drying, the moisture content drops to 0.5%. Remove them and cool them to room temperature for later use.

[0077] S2. Add the graphene-modified graphite powder, nickel-plated carbon fiber, and polycarboxylate superplasticizer from the composite conductive filler to 7 parts of deionized water. Set the stirring speed to 800 r / min and stir continuously for 20 minutes to ensure that each component is fully dispersed and forms a uniform conductive slurry.

[0078] S3. Add the industrial solid waste substrate pretreated in step S1, as well as the sulfoaluminate cement, metakaolin, and sodium silicate in the modified inorganic binder to the conductive slurry. Adjust the stirring speed to 1500 r / min and stir for 35 minutes to obtain a uniform and stable plastic aggregate mixture.

[0079] S4. The aggregate mixture is put into a hydraulic forming machine, and the forming pressure is set to 18 MPa and the pressure holding time is set to 6 minutes, and a cylindrical aggregate green body with a diameter of 15 mm is pressed.

[0080] S5. The aggregate green body is put into a curing chamber, and first cured for 4 days under the condition of a temperature of 25℃ and a humidity of 90%, then the temperature of the curing chamber is adjusted to 50℃ and the humidity is adjusted to 85%, and the curing is continued for 3 days, and finally the natural cooling is performed at a rate of 2℃ / h to room temperature, and the sinter-free artificial aggregate product with electrical conductivity is obtained.

[0081] The performance test of the sinter-free artificial aggregate product in this embodiment shows that the compressive strength is 32 MPa, the volume resistivity is 1.5Ω·m, the water absorption is 6.8%, and the resistance impedance fluctuation is ±7.9% in the temperature range of -30℃ to 70℃, which meets the basic performance requirements of concrete structure monitoring.

[0082] Based on the above sinter-free artificial aggregate, an intelligent monitoring concrete system is built, the sinter-free artificial aggregate is pre-buried in a C50 concrete test block at a spacing of 50 cm, and the connection points of the electrode and the shielding wire are sealed with epoxy resin sealant; the collection frequency of the electric parameter collection unit is set to 800Hz, the resistance impedance threshold of the intelligent analysis unit is preset to 1200-1600Ω; the transmission distance of the data transmission unit is set to 2.5km.

[0083] The damage simulation test of the system is as follows:

[0084] (1) A linear crack with a width of 0.2mm is cut on the surface of the concrete test block, the system monitors that the resistance impedance rises from 1400Ω to 1750Ω (an increase of 25%), triggers the early warning within 12s, and the recognition accuracy is 98%;

[0085] (2) The humidity inside the test block is increased to more than 95%, the resistance impedance decreases from 1400Ω to 1150Ω, and the early warning is triggered within 10s, and the recognition accuracy is 98%;

[0086] (3) An 18MPa pressure is applied to the test block, the resistance impedance fluctuates from 1400Ω to 1510Ω, and the early warning is triggered within 15s, and the recognition accuracy is 88%.

[0087] Embodiment 3: This embodiment specifically relates to a sinter-free artificial aggregate with electrical conductivity and a preparation method and application method thereof, and the mass components of the sinter-free artificial aggregate are as follows: industrial solid waste base material 60 parts, composite conductive filler 20 parts, modified inorganic binder 18 parts, functional additive 5 parts, and water 11 parts.

[0088] Among them, the mass components of the industrial solid waste base material are: steel slag 40 parts, and slag powder 20 parts.

[0089] The mass components of the composite conductive filler are: graphene modified graphite powder 16 parts, nickel plated carbon fiber 4 parts.

[0090] The mass components of the modified inorganic binder are: sulphoaluminate cement 9 parts, metakaolin 5.4 parts, sodium silicate 3.6 parts.

[0091] The mass components of the functional additive are: polycarboxylic acid water reducer 3.75 parts, nano calcium carbonate 1.25 parts.

[0092] As shown in the preparation method of the sintering-free conductive artificial aggregate in the embodiment includes the following steps: Figure 1

[0093] S1. The steel slag and slag powder are placed in a drying oven and dried at a temperature of 110°C for 2 hours. After drying, the water content is reduced to 0.4%, and the mixture is taken out and cooled to room temperature for use.

[0094] S2. The composite conductive filler and polycarboxylic acid water reducer are added to 11 parts of deionized water, the stirring rate is set to 1200 r / min, and stirring is carried out for 15 minutes to form a highly dispersed conductive slurry.

[0095] S3. The pretreated industrial solid waste substrate and modified inorganic binder are added to the conductive slurry, the stirring rate is increased to 2000 r / min, and stirring is carried out for 25 minutes to ensure that the materials are fully integrated, obtaining a plastic aggregate mixture.

[0096] S4. The mixture is placed in a hydraulic forming machine, the forming pressure is set to 25 MPa, and the pressure holding time is set to 4 minutes, and a cylindrical aggregate green body with a diameter of 15 mm is pressed.

[0097] S5. The aggregate green body is transferred to a curing chamber, first cured at a temperature of 30°C and a humidity of 95% for 4 days, then the temperature of the curing chamber is adjusted to 60°C and the humidity is adjusted to 90%, and the curing is continued for 3 days, finally naturally cooled to room temperature at a rate of 3°C / h, obtaining the sintering-free conductive artificial aggregate product.

[0098] The sintering-free conductive artificial aggregate product in the embodiment is tested for performance, and the results show that the compressive strength is 40 MPa, the volume resistivity is 0.3 Ω·m, the water absorption is 5.2%, and the resistance fluctuation is ±5.8% in the temperature range of -30°C to 70°C, with excellent mechanical properties and conductive stability.

[0099] ​Based on the above intelligent monitoring system of concrete, the non-burnt artificial aggregate is pre-embedded in the C50 concrete test block at an interval of 20 cm, and the electrode and shielding wire connection point is sealed with epoxy resin sealant; the collection frequency of the electric parameter collection unit is set to 1.2 kHz, and the preset resistance threshold of the intelligent analysis unit is 500-800Ω; the transmission distance of the data transmission unit is set to 3.5 km.

[0100] The results of the damage simulation test of the system are as follows:

[0101] (1) Crack damage simulation: a linear crack of 0.15 mm wide is cut on the surface of the concrete test block, the system monitors that the resistance rises from 650Ω to 810Ω, triggers the early warning within 8s, and the recognition accuracy is 100%;

[0102] Humidity anomaly simulation: the humidity inside the test block is increased to more than 90%, the resistance decreases from 650Ω to 550Ω, and the early warning is triggered within 6s, with a recognition accuracy of 100%;

[0103] Stress damage simulation: 22MPa pressure is applied to the test block, the resistance fluctuates from 650Ω to 687Ω, and the early warning is triggered within 10s, with a recognition accuracy of 95%.

[0104] As shown in Table 1, the performance of the non-burnt artificial aggregate and the intelligent monitoring system under different components and preparation methods in Example 1, Example 2 and Example 3 can be compared, and it can be found that the non-burnt artificial aggregate in Example 3 can obtain higher compressive strength and lower resistivity, so that it can obtain shorter crack early warning response time, shorter humidity anomaly early warning response time, shorter stress damage early warning response time, and higher average damage recognition accuracy in the process of intelligent monitoring.

[0105]

[0106] Table 1: Comparison table of performance of non-burnt artificial aggregate and intelligent monitoring system under different components and preparation methods in different examples.

Claims

1. A method for producing a non-fired electrically conductive artificial aggregate, characterized by The non-burning artificial aggregate comprises the following mass components: industrial solid waste substrate 60-75 parts, composite conductive filler 12-20 parts, modified inorganic binder 10-18 parts, functional additive 2-5 parts, and water 7-11 parts; The industrial solid waste substrate is a mixture of steel slag and slag powder in a mass ratio of 2:1-1.5; The composite conductive filler is a mixture of graphene modified graphite powder and nickel-plated carbon fiber in a mass ratio of 4:1; The modified inorganic binder is a mixture of sulphoaluminate cement, metakaolin and sodium silicate in a mass ratio of 5:3:2; The functional additive is a mixture of polycarboxylic acid water reducer and nano calcium carbonate in a mass ratio of 3:1; The preparation method of the non-burning artificial aggregate comprises the following steps: S1: The industrial solid waste substrate is placed in a drying oven and dried at 105-110 DEG C for 2-3 hours to reduce the water content to less than or equal to 0.8%, and then cooled and reserved; S2: The composite conductive filler and the polycarboxylic acid water reducer in the functional additive are added to deionized water, stirred at a stirring rate of 800-1200 r / min for 15-20 minutes to form a uniform conductive slurry; S3: The pretreated industrial solid waste substrate, the modified inorganic binder and the nano calcium carbonate in the functional additive are added to the conductive slurry, and the stirring rate is adjusted to 1500-2000 r / min, and stirred for 25-35 minutes to obtain a plastic aggregate mixture; S4: The plastic aggregate mixture is put into a hydraulic forming machine, and formed under the conditions of a forming pressure of 18-25 MPa and a pressure holding time of 4-6 minutes to obtain a cylindrical aggregate green body with a diameter of 15 mm; S5: The aggregate green body is placed in a curing chamber, first cured at a temperature of 25-30 DEG C and a humidity of greater than or equal to 90% for 4 days, then cured at a temperature of 50-60 DEG C and a humidity of greater than or equal to 85% for 3 days, and finally naturally cooled to room temperature to obtain the non-burning artificial aggregate product with conductivity.

2. The method of claim 1, wherein the non-fired electrically conductive artificial aggregate is prepared by the steps of: a) mixing a binder, a conductive material, and a filler material; b) extruding the mixture into a desired shape; c) drying the extruded mixture; and d) sintering the dried mixture. The non-burning artificial aggregate comprises the following mass components: industrial solid waste substrate 60 parts, composite conductive filler 20 parts, modified inorganic binder 18 parts, functional additive 5 parts, and water 11 parts; The industrial solid waste substrate is a mixture of steel slag and slag powder in a mass ratio of 2:1; The composite conductive filler is a mixture of graphene modified graphite powder and nickel-plated carbon fiber in a mass ratio of 4:1; The modified inorganic binder is a mixture of sulphoaluminate cement, metakaolin and sodium silicate in a mass ratio of 5:3:2; The functional additive is a mixture of polycarboxylic acid water reducer and nano calcium carbonate in a mass ratio of 3:

1. The natural cooling rate in step S5 is 2-3 DEG C / h.

3. The method for preparing a conductive, non-fired artificial aggregate according to claim 1, characterized in that... The preparation method of the graphene modified graphite powder in the composite conductive filler comprises the following steps: mixing graphite powder and graphene dispersion liquid in a mass ratio of 10:1, ultrasonic dispersion for 20-30 minutes under an ultrasonic power of 300-500 W, and drying to obtain; wherein the mass concentration of the graphene dispersion liquid is 0.5%.

4. The method for preparing a conductive, non-fired artificial aggregate according to claim 1, characterized in that...

5. A non-burning artificial aggregate prepared by the preparation method of the non-burning artificial aggregate with conductivity according to claim 1. The application method comprises the following steps:

6. A method of using the non-fired artificial aggregate according to claim 5, characterized by ​ (S1) the non-burned artificial aggregate is pre-buried in the concrete in a rectangular array manner, the distance between adjacent non-burned artificial aggregates is 20-50 cm, the surface of the non-burned artificial aggregate is provided with a copper lead-out electrode, the copper lead-out electrode is connected with an electric parameter acquisition unit outside the concrete through a shielding wire, the electric parameter acquisition unit is connected with an intelligent analysis unit through a data transmission unit, and the intelligent analysis unit is connected with a terminal display unit; (S2) the electric parameter acquisition unit measures the electric impedance value between the non-burned artificial aggregates in real time by using an impedance analyzer, the electric parameter acquisition unit transmits the collected data to the intelligent analysis unit through the data transmission unit for analysis and judgment, the electric impedance threshold range under the normal state of the concrete is preset, and whether the concrete has cracks, abnormal humidity or stress damage is judged by comparing the deviation of the real-time electric impedance value and the threshold range.

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