CN-122008403-A - Preparation process of graphene concrete

CN122008403ACN 122008403 ACN122008403 ACN 122008403ACN-122008403-A

Abstract

The application relates to a preparation process of graphene concrete, which relates to the technical field of concrete and comprises the steps of carrying out in-situ acrylic acid molecular brush grafting modification on graphene, then carrying out ultrasonic-centrifugal synergistic grading, separating into an interface enhancement component rich in large-size lamellae and a pore filling component rich in small-size lamellae, spraying the interface enhancement component onto the surface of coarse aggregate, carrying out micro-area flash solidification anchoring by aid of dry cement powder, forming a semi-rigid hard shell on the surface of the aggregate, introducing a composite corrosion inhibitor into the pore filling component, mixing with a cementing material, and initiating secondary crosslinking of residual monomers by utilizing hydration heat. According to the method, bridging enhancement of large-size graphene to an aggregate interface transition region and filling of small-size graphene to a matrix micropore are realized through a grading directional distribution strategy, and the problems of graphene agglomeration, size mismatch and poor alkali resistance are solved by matching with a chemical passivation and secondary crosslinking technology, so that the mechanical strength, compactness and conductive stability of concrete are remarkably improved.

Inventors

TONG XIAOGEN
ZHANG KAIFENG
FANG JIESHENG
ZHANG XINSHENG
WANG MIN
LI YIFEI
QI ZHAODONG

Assignees

中建西部建设第九有限公司

Dates

Publication Date: 20260512
Application Date: 20260304

Claims (10)

1. The preparation process of the graphene concrete is characterized by comprising the following steps of: s1, reducing graphene oxide, dispersing the reduced graphene oxide in water, adding an acrylic acid monomer and an initiator, and carrying out in-situ polymerization reaction to obtain a modified graphene dispersion liquid of which the surface is grafted with a polyacrylic acid molecular brush; S2, placing the modified graphene dispersion liquid prepared in the step S1 into an ultrasonic-centrifugal synergistic dispersion system, performing ultrasonic treatment under the conditions of 20kHz frequency and 0.5W/mL power density, performing centrifugal separation, collecting the sediment after centrifugation as an interface enhancement component, and collecting the supernatant after centrifugation as a pore filling component; s3, spraying the interface reinforcing component onto the surface of the coarse aggregate in a rolling state, then spraying dry cement powder accounting for 2-5% of the total mass of cement onto the surface of the coarse aggregate, and carrying out rolling stirring and standing to form a semi-rigid crust formed by cement hydration products on the surface of the coarse aggregate; s4, adding sodium pyrophosphate and sodium tripolyphosphate into the pore filling component, wherein the mass ratio of the sodium pyrophosphate to the sodium tripolyphosphate is 1:2, and preparing composite modified liquid; mixing and stirring cement, fine aggregate, water and the composite modifying liquid to prepare a mortar matrix, adding the coarse aggregate treated in the step S3 into the mortar matrix, mixing, and pouring and molding to obtain the graphene concrete.
2. The preparation process of graphene concrete according to claim 1, wherein in the in-situ polymerization reaction in step S1, the polymerization reaction time is controlled so that the thickness of the polyacrylic acid molecular brush on the surface of the modified graphene is 5nm to 10nm, and the unreacted acrylic acid monomer residues in the dispersion liquid are retained without cleaning and purification after the reaction is completed.
3. The preparation process of graphene concrete according to claim 2, wherein in the in-situ polymerization reaction in step S1, the mass ratio of the acrylic acid monomer to the reduced graphene oxide is 10:1 to 20:1, the initiator is ammonium persulfate, and the amount of ammonium persulfate is 1.0% to 2.0% of the mass of the acrylic acid monomer.
4. The preparation process of graphene concrete according to claim 1, wherein the centrifugal separation in the step S2 is a step-type centrifugal separation, and the specific process is as follows: The interfacial reinforcing component is separated by first centrifuging at 3000 to 5000rpm for 10 to 20 minutes, and the pore-filling component is separated by subsequently centrifuging the remaining liquid at 8000 to 10000rpm for 20 to 30 minutes.
5. The preparation process of graphene concrete according to claim 1, wherein the interface enhancing component in step S3 is rich in large-size graphene sheets; and step S3, the pore filling component is rich in small-size and single-layer graphene sheets.
6. The process of claim 1, wherein the tumbling in step S3 is performed for 30 seconds to 60 seconds, the standing is performed for 2 minutes to 5 minutes, and the hydration reaction of the dry cement powder is induced by the moisture in the interfacial reinforcing component to form the semi-rigid crust.
7. The preparation process of graphene concrete according to claim 1, wherein in the step S4, sodium pyrophosphate and sodium tripolyphosphate form a composite corrosion inhibitor, and the total addition amount of the composite corrosion inhibitor is 20-30% of the mass of graphene.
8. The preparation process of graphene concrete according to claim 2, wherein in the mixing and stirring process in step S4, the slurry temperature is monitored, and the hydration heat of 40 ℃ to 60 ℃ generated by cement hydration is used as a heat source to initiate the secondary crosslinking reaction between the acrylic monomer residues retained in step S1 and the cement matrix.
9. The preparation process of graphene concrete according to claim 1, wherein the preparation process comprises the following step S1 The monolayer rate of the graphene oxide is larger than 98%, the sheet diameter range is 0.5-5 microns, hydrazine hydrate is used as a reducing agent in the reduction in the step S1, and the mass ratio of the hydrazine hydrate to the graphene oxide is 2:1.
10. The preparation process of graphene concrete according to claim 1, wherein the water-cement ratio of the graphene concrete in step S4 is controlled to be 0.40; The coarse aggregate is continuous graded broken stone with the grain diameter of 5-20 mm, and the fine aggregate is natural river sand with the fineness modulus of 2.6-2.9.

Description

Preparation process of graphene concrete Technical Field The application relates to the technical field of concrete, in particular to a preparation process of graphene concrete. Background Graphene is used for modifying cement-based composite materials due to its excellent mechanical properties and electrical properties. However, in the actual preparation process, graphene has a high specific surface area, strong van der Waals force exists between the sheets, and a pore solution generated by cement hydration has high ionic strength, so that the graphene is easy to agglomerate in a cement matrix. The agglomeration phenomenon not only reduces the utilization rate of the specific surface area of the graphene and prevents the construction of a continuous conductive network, but also can become a defect and a stress concentration source in a matrix, so that the mechanical property of the concrete is reduced. The existing preparation technology generally takes graphene as a single component to be directly doped, and ignores the matching relation between the polydispersion characteristic of the size of the graphene raw material and the multistage pore structure of the concrete. The concrete is a heterogeneous multiphase material consisting of coarse aggregate, fine aggregate and hardened cement slurry, wherein the interface transition area between the coarse aggregate and the slurry has a loose structure, and is a weak link of mechanical properties. If large-size graphene sheets are introduced into the nanoscale gel pores, steric hindrance is easily generated due to size mismatch, and compactness of a matrix microstructure is damaged, and if small-size graphene sheets are distributed on the surface of coarse aggregate, effective bridging and crack resistance at an interface are difficult to play due to insufficient span. The randomness of the spatial distribution causes that the graphene can not pertinently strengthen an interface transition area, and the improvement of the overall performance of the concrete is limited. In addition, the cement hydration environment is strongly alkaline, and the pH value of the pore solution is usually above 13. Under the environment, oxygen-containing functional groups and edge defect sites on the surface of graphene are easy to chemically erode, so that the lattice structure is damaged. The structural degradation can cause the breakage of the conductive path and the attenuation of the reinforcing effect, thereby affecting the durability and the functional stability of the graphene concrete in the long-term service process. Aiming at the related technology, a preparation process of graphene concrete is provided. Disclosure of Invention The application aims to provide a preparation process of graphene concrete, which solves the technical problems of poor dispersion uniformity, mismatching of size distribution and matrix structure and insufficient long-term stability of graphene in a strong alkali environment in the prior art. By adopting the technical scheme: the invention provides a preparation process of graphene concrete, which realizes graded distribution and in-situ passivation of graphene in a concrete matrix by carrying out in-situ chemical modification, hydrodynamic grading, aggregate interface micro-area flash anchoring and dual-phase targeting grouting on graphene. The preparation process specifically comprises the following steps: S1, dispersing graphene oxide in water after reduction, and adding an acrylic acid monomer and an initiator to perform in-situ polymerization reaction. In the process, acrylic acid monomer is subjected to graft polymerization on the surface of reduced graphene oxide to prepare modified graphene dispersion liquid with the surface grafted with a polyacrylic acid molecular brush. The thickness of the polyacrylic acid molecular brush layer is controlled between 5nm and 10nm. The modified layer is chemically bonded with a subsequent cement hydration product through carboxyl groups on one hand, and is used as a physical barrier to prevent hydroxide ions in alkaline pore solution from directly contacting graphene lattices on the other hand; S2, placing the modified graphene dispersion liquid into an ultrasonic-centrifugal synergistic dispersion system. Ultrasonic cavitation treatment is firstly carried out under the conditions of 20kHz frequency and 0.5W/mL power density, and Van der Waals force between the sheet layers is opened. And then carrying out step-type centrifugal separation, namely centrifuging for 10 to 20 minutes at a speed of 3000 to 5000rpm, collecting sediment to obtain an interface enhancement component which is rich in large-size graphene sheets, centrifuging the rest liquid for 20 to 30 minutes at a speed of 8000 to 10000rpm, and collecting supernatant to obtain a pore filling component which is rich in small-size and single-layer graphene sheets. Through this step, the polydisperse graphene feedstock is separated into two-phase fl