CN110857246A - Graphene oxide compounded cement mortar and preparation method thereof - Google Patents

Graphene oxide compounded cement mortar and preparation method thereof Download PDF

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CN110857246A
CN110857246A CN201810962679.0A CN201810962679A CN110857246A CN 110857246 A CN110857246 A CN 110857246A CN 201810962679 A CN201810962679 A CN 201810962679A CN 110857246 A CN110857246 A CN 110857246A
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cement
graphene oxide
water
cement mortar
reducing agent
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曹靖
王奕璇
杨毅
张鲜维
覃源
许增光
柴军瑞
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Xian University of Technology
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Xian University of Technology
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C04B28/04—Portland cements
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B14/02—Granular materials, e.g. microballoons
    • C04B14/022—Carbon
    • C04B14/024—Graphite
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Civil Engineering (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)

Abstract

The invention discloses graphene oxide composite cement mortar which is prepared by mixing and stirring cement, water, sand, a water reducing agent and graphene oxide serving as raw materials to form the cement mortar, wherein the cement and the sand are mixed according to the mass ratio of 1:3, the water-cement ratio is 0.35, the doping amount of the graphene oxide is 0.01-0.07 wt% of the mass of cement solids, and the doping amount of the water reducing agent is 0.198-0.306 wt% of the mass of the cement solids. The graphene oxide composite cement mortar solves the problem that the cement mortar is expensive in manufacturing cost due to the use of small-diameter thin graphene oxide in the prior art. The invention also discloses a preparation method of the cement mortar.

Description

Graphene oxide compounded cement mortar and preparation method thereof
Technical Field
The invention belongs to the technical field of cement mortar, relates to graphene oxide compounded cement mortar, and further relates to a preparation method of the cement mortar.
Background
The cement is one of the most used building materials at present, and is widely applied to hydraulic engineering construction. But the bending strength is low and the crack resistance is poor[1]Limiting the development of cement. The microcracks are expanded and developed into macrocracks by external force, and have great influence on the macroscopic mechanical properties of the cement material. In recent years, nano materials such as carbon nanotubes, carbon fibers and graphene have attracted attention due to their ultrahigh strength and stretchability, and are widely used to improve various properties of composite materials. Therefore, the geometrical structure of the cement material on the microscopic scale can be optimized by blending the nano material, and the mechanical property, durability, impermeability and other characteristics of the cement material can be improved.
Graphene Oxide (GO) is an oxidation product of graphene. The same as graphene, GO has excellent mechanical properties, the tensile strength of multilayer GO is as high as 130Mpa, and the basal plane of the multilayer GO contains a large number of oxygen-containing groups, so that GO has an ultra-large specific surface area and surface chemistry. In addition, due to the existence of the oxygen-containing group, the polymer has good dispersibility in water. Thus, GO can interact with other materials, improving the strength and stretchability of the composite. The production process of GO is simple, and the raw materials are cheap, thus providing a good foundation for the wide application of GO.
Although many researches are carried out on the influence of GO doped in a cement-based material on the performance of the GO, most of GO is concentrated on small-diameter thin layers, and although the mechanical performance of the cement-based material is greatly enhanced, the small-diameter thin layer GO material is complex in manufacturing process and expensive in manufacturing cost, so that the wide application of the material is influenced.
Disclosure of Invention
The invention aims to provide graphene oxide compounded cement mortar, and solves the problem that in the prior art, small-diameter thin-layer graphene oxide is used to cause high cost of cement mortar.
The invention also aims to provide a preparation method of the cement mortar.
The technical scheme adopted by the invention is that the graphene oxide compounded cement mortar is formed by mixing and stirring cement, water, sand, a water reducing agent and graphene oxide serving as raw materials, wherein the cement and the sand are mixed according to the mass ratio of 1:3, the water cement ratio is 0.35, the doping amount of the graphene oxide is 0.01-0.07 wt% of the mass of cement solids, and the doping amount of the water reducing agent is 0.198-0.306 wt% of the mass of the cement solids.
The first aspect of the present invention is also characterized in that,
the cement is portland cement.
The water reducing agent is a polycarboxylic acid type water reducing agent.
The water reducing rate of the water reducing agent is 25%, and the initial solid content is 18%.
When the doping amount of the graphene oxide in the cement mortar is increased by 0.01%, the doping amount of the water reducing agent is increased by 0.018%.
The graphene oxide adopts multilayer graphene oxide powder.
The other technical scheme adopted by the invention is that the preparation method of the graphene oxide composite cement mortar takes cement, water, sand, a water reducing agent and graphene oxide as raw materials, and the cement mortar is formed by mixing and stirring the raw materials, wherein the cement and the sand are mixed according to the mass ratio of 1:3, the water-cement ratio is 0.35, the doping amount of the graphene oxide is 0.01-0.07 wt% of the mass of cement solids, and the doping amount of the water reducing agent is 0.198-0.306 wt% of the mass of the cement solids; the preparation process comprises the following steps: firstly, preparing a graphene oxide dispersion liquid, then weighing cement, water, sand, a water reducing agent and the graphene oxide dispersion liquid according to the proportion, then sequentially adding the water, the graphene oxide dispersion liquid and the water reducing agent into a container for stirring, fully mixing to obtain a mixed solution, then placing the cement and the sand into a stirring pot for stirring, standing for 8-12 seconds after the cement and the sand are uniformly stirred, and then pouring the mixed solution into the stirring pot for stirring to obtain the cement mortar.
The second aspect of the present invention is also characterized in that,
the process for preparing the graphene oxide dispersion liquid comprises the following steps: and (2) ultrasonically dispersing a certain amount of graphene oxide powder in a certain amount of deionized water for 15-25min to prepare a graphene oxide dispersion liquid with the concentration of 2 g/L.
The cement and sand were put in a stirring pot and stirred with a stirrer at 62rpm for 1 min.
The mixed solution is poured into a stirring pot, and then stirred for 2min at 62rpm by using a stirrer, and then stirred for 2min at 125 rpm.
The invention has the beneficial effects that:
according to the invention, the large-sheet-diameter multilayer graphene oxide is doped into the cement-based material, the prepared cement mortar has a compact structure after being cured, the compressive strength and the bending strength meet the requirements, the large-sheet-diameter multilayer graphene oxide is simple in manufacturing process and low in manufacturing cost, and the manufacturing cost of the cement mortar is reduced.
Drawings
FIG. 1 is a graph of compressive strength of cement mortar prepared according to the present invention after curing as a function of GO doping and hydration age;
FIG. 2 is a graph of flexural strength of cement mortar after curing according to the present invention as a function of GO doping amount and hydration age;
FIG. 3 is a microstructure diagram of cement mortars of the present invention blended with varying amounts of GO;
FIG. 4 is a microstructure diagram of the cement mortar with 0.05 wt% GO of the present invention cured at different ages.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention relates to graphene oxide composite cement mortar which is prepared by mixing and stirring cement, water, sand, a water reducing agent and graphene oxide serving as raw materials to form cement mortar, wherein the cement and the sand are mixed according to a mass ratio of 1:3, the water-cement ratio is 0.35, the doping amount of the graphene oxide is 0.01-0.07 wt% of the mass of cement solids, and the doping amount of the water reducing agent is 0.198-0.306 wt% of the mass of the cement solids, wherein the cement is portland cement, the water reducing agent is a polycarboxylic acid type water reducing agent (PCE), the water reducing rate of the water reducing agent is 25%, the initial solid content is 18%, when the doping amount of the graphene oxide in the cement mortar is increased by 0.01%, the doping amount of the water reducing agent is increased by 0.018%, and the graphene oxide is multilayer graphene oxide powder.
The invention relates to a preparation method of graphene oxide composite cement mortar, which takes cement, water, sand, a water reducing agent and graphene oxide as raw materials, and the cement mortar is formed by mixing and stirring the raw materials, wherein the cement and the sand are mixed according to the mass ratio of 1:3, the water-cement ratio is 0.35, the doping amount of the graphene oxide is 0.01-0.07 wt% of the mass of cement solids, the doping amount of the water reducing agent is 0.198-0.306 wt% of the mass of the cement solids, and when the doping amount of the graphene oxide in the cement mortar is increased by 0.01%, the doping amount of the water reducing agent is increased by 0.018%, and the preparation process is as follows: firstly, ultrasonically dispersing a certain amount of graphene oxide powder in a certain amount of deionized water for 15-25min to prepare graphene oxide dispersion liquid with the concentration of 2g/L, then weighing cement, water, sand, a water reducing agent and the graphene oxide dispersion liquid according to the proportion, then sequentially adding the water, the graphene oxide dispersion liquid and the water reducing agent into a container for stirring to fully mix the graphene oxide dispersion liquid and the water reducing agent to obtain mixed solution, then placing the cement and the sand into a stirring pot, stirring the mixture for 1min at 62rpm by using a stirrer, standing the mixture for 8-12S, then pouring the mixed solution into the stirring pot, stirring the mixture for 2min at 62rpm by using the stirrer, and then stirring the mixture for 2min at 125rpm to prepare cement mortar.
The sand of the invention adopts ordinary portland cement (PO 42.5) produced by Xiamen Escio company, and the parameters of the multilayer graphene oxide powder material are shown in Table 1;
TABLE 1
Diameter (μm) Thickness (nm) Number of layers Specific surface area (m)2g-1)
10-50 3.4-7.0 5-10 100-300
Example 1
The preparation method of the graphene oxide composite cement mortar comprises the following steps of mixing and stirring cement, water, sand, a water reducing agent and graphene oxide serving as raw materials to form the cement mortar, wherein the cement and the sand are mixed according to a mass ratio of 1:3, the water-cement ratio is 0.35, the doping amount of the graphene oxide is 0.01 wt% of the mass of cement solids, the doping amount of the water reducing agent is 0.198 wt% of the mass of the cement solids, and the preparation process comprises the following steps: firstly, ultrasonically dispersing a certain amount of graphene oxide powder in a certain amount of deionized water for 20min to prepare graphene oxide dispersion liquid with the concentration of 2g/L, then weighing cement, water, sand, a water reducing agent and the graphene oxide dispersion liquid according to the proportion, then sequentially adding the water, the graphene oxide dispersion liquid and the water reducing agent into a container to be stirred, fully mixing the water, the graphene oxide dispersion liquid and the water reducing agent to obtain mixed solution, then placing the cement and the sand into a stirring pot, stirring the mixture for 1min at 62rpm by using a stirrer, standing the mixture for 10S, then pouring the mixed solution into the stirring pot, stirring the mixed solution for 2min at 62rpm by using the stirrer, and then stirring the mixture for 2min at 125rpm to prepare cement mortar.
Example 2
The preparation method of the graphene oxide composite cement mortar comprises the following steps of mixing and stirring cement, water, sand, a water reducing agent and graphene oxide serving as raw materials to form the cement mortar, wherein the cement and the sand are mixed according to a mass ratio of 1:3, the water-cement ratio is 0.35, the doping amount of the graphene oxide is 0.03 wt% of the mass of cement solids, the doping amount of the water reducing agent is 0.234 wt% of the mass of the cement solids, and the preparation process comprises the following steps: firstly, ultrasonically dispersing a certain amount of graphene oxide powder in a certain amount of deionized water for 20min to prepare graphene oxide dispersion liquid with the concentration of 2g/L, then weighing cement, water, sand, a water reducing agent and the graphene oxide dispersion liquid according to the proportion, then sequentially adding the water, the graphene oxide dispersion liquid and the water reducing agent into a container to be stirred, fully mixing the water, the graphene oxide dispersion liquid and the water reducing agent to obtain mixed solution, then placing the cement and the sand into a stirring pot, stirring the mixture for 1min at 62rpm by using a stirrer, standing the mixture for 10S, then pouring the mixed solution into the stirring pot, stirring the mixed solution for 2min at 62rpm by using the stirrer, and then stirring the mixture for 2min at 125rpm to prepare cement mortar.
Example 3
The preparation method of the graphene oxide composite cement mortar comprises the following steps of mixing and stirring cement, water, sand, a water reducing agent and graphene oxide serving as raw materials to form the cement mortar, wherein the cement and the sand are mixed according to a mass ratio of 1:3, the water-cement ratio is 0.35, the doping amount of the graphene oxide is 0.05 wt% of the mass of cement solids, the doping amount of the water reducing agent is 0.27 wt% of the mass of the cement solids, and the preparation process comprises the following steps: firstly, ultrasonically dispersing a certain amount of graphene oxide powder in a certain amount of deionized water for 20min to prepare graphene oxide dispersion liquid with the concentration of 2g/L, then weighing cement, water, sand, a water reducing agent and the graphene oxide dispersion liquid according to the proportion, then sequentially adding the water, the graphene oxide dispersion liquid and the water reducing agent into a container to be stirred, fully mixing the water, the graphene oxide dispersion liquid and the water reducing agent to obtain mixed solution, then placing the cement and the sand into a stirring pot, stirring the mixture for 1min at 62rpm by using a stirrer, standing the mixture for 10S, then pouring the mixed solution into the stirring pot, stirring the mixed solution for 2min at 62rpm by using the stirrer, and then stirring the mixture for 2min at 125rpm to prepare cement mortar.
Example 4
The preparation method of the graphene oxide composite cement mortar comprises the following steps of mixing and stirring cement, water, sand, a water reducing agent and graphene oxide serving as raw materials to form the cement mortar, wherein the cement and the sand are mixed according to a mass ratio of 1:3, the water-cement ratio is 0.35, the doping amount of the graphene oxide is 0.07 wt% of the mass of cement solids, the doping amount of the water reducing agent is 0.306 wt% of the mass of the cement solids, and the preparation process comprises the following steps: firstly, ultrasonically dispersing a certain amount of graphene oxide powder in a certain amount of deionized water for 20min to prepare graphene oxide dispersion liquid with the concentration of 2g/L, then weighing cement, water, sand, a water reducing agent and the graphene oxide dispersion liquid according to the proportion, then sequentially adding the water, the graphene oxide dispersion liquid and the water reducing agent into a container to be stirred, fully mixing the water, the graphene oxide dispersion liquid and the water reducing agent to obtain mixed solution, then placing the cement and the sand into a stirring pot, stirring the mixture for 1min at 62rpm by using a stirrer, standing the mixture for 10S, then pouring the mixed solution into the stirring pot, stirring the mixed solution for 2min at 62rpm by using the stirrer, and then stirring the mixture for 2min at 125rpm to prepare cement mortar.
Example 5
The preparation method of the graphene oxide composite cement mortar comprises the following steps of mixing and stirring cement, water, sand, a water reducing agent and graphene oxide serving as raw materials to form the cement mortar, wherein the cement and the sand are mixed according to a mass ratio of 1:3, the water-cement ratio is 0.35, the doping amount of the graphene oxide is 0.04 wt% of the mass of cement solids, the doping amount of the water reducing agent is 0.252 wt% of the mass of the cement solids, and the preparation process comprises the following steps: firstly, ultrasonically dispersing a certain amount of graphene oxide powder in a certain amount of deionized water for 15min to prepare graphene oxide dispersion liquid with the concentration of 2g/L, then weighing cement, water, sand, a water reducing agent and the graphene oxide dispersion liquid according to the proportion, then sequentially adding the water, the graphene oxide dispersion liquid and the water reducing agent into a container to be stirred, fully mixing the water, the graphene oxide dispersion liquid and the water reducing agent to obtain mixed solution, then putting the cement and the sand into a stirring pot, stirring the mixture for 1min at 62rpm by using a stirrer, standing the mixture for 8S, then pouring the mixed solution into the stirring pot, stirring the mixed solution for 2min at 62rpm by using the stirrer, and then stirring the mixed solution for 2min at 125rpm to prepare cement mortar.
Example 6
The preparation method of the graphene oxide composite cement mortar comprises the following steps of mixing and stirring cement, water, sand, a water reducing agent and graphene oxide serving as raw materials to form the cement mortar, wherein the cement and the sand are mixed according to a mass ratio of 1:3, the water-cement ratio is 0.35, the doping amount of the graphene oxide is 0.06 wt% of the mass of cement solids, and the doping amount of the water reducing agent is 0.288 wt% of the mass of the cement solids, and the preparation process comprises the following steps: firstly, ultrasonically dispersing a certain amount of graphene oxide powder in a certain amount of deionized water for 25min to prepare graphene oxide dispersion liquid with the concentration of 2g/L, then weighing cement, water, sand, a water reducing agent and the graphene oxide dispersion liquid according to the proportion, then sequentially adding the water, the graphene oxide dispersion liquid and the water reducing agent into a container to be stirred, fully mixing the water, the graphene oxide dispersion liquid and the water reducing agent to obtain mixed solution, then putting the cement and the sand into a stirring pot, stirring the mixture for 1min at 62rpm by using a stirrer, standing the mixture for 12S, then pouring the mixed solution into the stirring pot, stirring the mixed solution for 2min at 62rpm by using the stirrer, and then stirring the mixed solution for 2min at 125rpm to prepare cement mortar.
The performance of the cement mortar prepared by the invention is not verified, and the performance is compared and researched by adopting examples 1-4 and a comparison group:
comparison group
The preparation method of the graphene oxide composite cement mortar comprises the following steps of mixing and stirring cement, water, sand and a water reducing agent serving as raw materials to form the cement mortar, wherein the cement and the sand are mixed according to a mass ratio of 1:3, the water cement ratio is 0.35, the mixing amount of the water reducing agent is 0.18 wt% of the mass of cement solids, and the preparation process comprises the following steps: weighing cement, water, sand and a water reducing agent according to the proportion, then sequentially adding the water and the water reducing agent into a container for stirring, fully mixing to obtain a mixed solution, then placing the cement and the sand into a stirring pot, stirring for 1min at 62rpm by using a stirrer, standing for 12S, then pouring the mixed solution into the stirring pot, stirring for 2min at 62rpm by using the stirrer, and then stirring for 2min at 125rpm to prepare the cement mortar.
Concrete data of examples 1 to 4 and comparative example As shown in Table 2, cement mortars prepared in examples 1 to 4 and comparative example were poured into molds having sizes of 70.7mm x 70.7mm and 40mm x 160mm for testing the compression strength and bending strength of cement mortar, respectively, and after 24 hours, the test pieces were taken out of the molds and cured to ages of 7 days, 14 days and 28 days in an environment having a temperature of 20 + -1 deg.C and a relative humidity of 95% for testing.
The compression strength and the bending strength of the cement mortar are tested according to the test standard of the cement mortar strength test method (ISO method) (GB 17671-1999). The compression strength and the bending strength are tested by using a WAW-3000C microcomputer control electro-hydraulic servo universal tester, the loading rate of the compression strength is 2.4 +/-0.5 kN/s, the loading rate of the bending strength is 0.05 +/-0.01 kN/s, and three samples are tested in each proportion.
TABLE 2
Figure BDA0001774174000000091
(1) Compressive strength
The addition of graphene oxide to cement mortar changes the consistency of mortar and reduces the fluidity of mortar, experiments keep the consistency of mortar within a certain range by adjusting the mixing amount of the water reducing agent (keep the consistency of cement mortar within 23-24 mm by changing the mixing amount of the water reducing agent), and table 3 shows mechanical properties such as compressive strength and flexural strength of cement mortar with the mixing amounts of graphene oxide of 0 wt%, 0.01 wt%, 0.03 wt%, 0.05 wt% and 0.07 wt% at different ages. Fig. 1 shows the compressive strength as a function of GO incorporation (0 wt%, 0.01 wt%, 0.03 wt%, 0.05 wt%, and 0.07 wt%) and hydration age (7 days, 14 days, and 28 days), and it can be seen that the flexural strength of cement mortar increases with the increase of cement hydration age, that the compressive strength of cement mortar increases with the incorporation of less than 0.05 wt%, and that the compressive strength is less than that of 0.05 wt% when the incorporation is continuously increased to 0.07 wt%. The breaking strength of the cement mortar is greatly increased along with the addition of GO, wherein 0.05 wt% of GO is added when the hydration age is 7 days, 14 days and 28 days, and the compressive strength of the cement mortar reaches the maximum values of 22%, 19% and 18% respectively. Therefore, GO has a significant improvement in the compressive strength of cement mortar. We analyzed the reasons for two: firstly, GO provides a growth carrier for a cement hydration product, namely calcium silicate hydrate, and accelerates the generation and development of the cement hydration product; secondly, GO plays a bridging role in the cement-based material, and comprises physical connection and chemical bond combination, so that the cement hydrated crystals and GO are tightly connected. Particularly, when the curing period is 7 days, the compressive strength is improved by 22% at the maximum. Because early hydration products are dispersed, GO serves as a carrier to promote a compact structure to be generated in cement, and the bridging effect on loose calcium silicate hydrate is better.
TABLE 3
(2) Bending strength
The flexural strength was varied with the GO content (0 wt%, 0.01 wt%, 0.03 wt%, 0.05 wt%, and 0.07 wt%) and the hydration age (7 days, 14 days, and 28 days) as shown in fig. 2, and it is clear from the graph that the flexural strength of the cement mortar increased with the increase in the cement hydration age, and the increase was gradually slowed down. When the cement hydration age is 7 days, 14 days and 28 days, the GO content has a large influence on the flexural strength of the cement mortar material, and when the GO is doped in 0.01 wt%, 0.03 wt% and 0.05 wt%, the flexural strength is gradually improved and the growth trend is slowed along with the increase of the GO doping amount. However, when the amount exceeds 0.05 wt%, the flexural strength is lowered relative to the maximum. There are two reasons for the analysis: firstly, when the GO is excessively doped, an agglomeration effect is generated, and the bridging effect on a cement hydrated crystal structure is weakened; the second reason is that the specific surface area is reduced after GO is agglomerated, the oxygen-containing groups on the surface are reduced, and the generation effect of cement hydrated crystals is weakened. It is noted that when GO is doped in the hydration period of 7 days, 14 days and 28 days, the breaking strength of the cement mortar reaches the maximum value, namely 29%, 17% and 17%. Particularly, when the hydration age is 7 days, the addition of GO obviously increases the flexural strength of a cement mortar test piece, so that the flexural strength of the cement mortar is improved by 15-28%. This shows that the GO has obvious toughening effect on cement mortar materials.
(3) Microstructure of cement hydrated crystal
The microstructure of the cement-based composite material determines the mechanical properties thereof. Therefore, the microstructure of the cement-based material is observed and analyzed by scanning through an electron microscope. The crystal produced by cement hydration has holes and cracks to form a large number of loose and defective networks, the doped graphene oxide is beneficial to the generation of cement hydration crystals (hydrated calcium silicate, C-S-H; ettringite, Aft; monothio hydrated aluminum sulfate, Afm; calcium hydroxide, CH), the specific surface area of the graphene oxide is large, and oxygen atoms contained on the graphene oxide provide sites for the hydration reaction of cement, so that the regular dense hydration products are promoted to be generated, and the compactness of the hydrated calcium silicate is improved. And the network formed by GO tightly connects the calcium silicate hydrate, thereby influencing the microstructure of the cement. At the hydration age of cement mortar of 1 day, fig. 3 shows the microstructure of cement mortar blended with different amounts of GO, the microstructure of the sample is scanned by an electron microscope, wherein (a) in fig. 3 is no GO; (b) - (e) respective amounts of GO of 0.01 wt%, 0.03 wt%, 0.05 wt%, 0.07 wt%, it can be clearly seen that the hydration product of cement mortar not blended with GO shows sparse needle-like crystals irregularly distributed, and when the amount of GO is 0.01 wt%, the needle-like crystals increase in the figure. When the content of GO is 0.03 wt%, the needle-shaped crystals are increased sharply, and the microstructure is densified. When the GO is doped in the range of 0.05 wt% to 0.07 wt%, a large number of flaky crystals are generated and gradually increased, and the result shows that the GO has a regulating effect on needle-shaped and flaky crystals, can promote the formation of a compact block structure, improve the microstructure of cement hydrate, and further enhance the mechanical properties of the cement-based material.
Figure 4 is a microstructure of cement-based materials blended with 0.05 wt% GO over different ages (1, 3, 7, 14 and 28 days) showing that the microstructure of the cement is denser with increasing age. When the hydration age is 1 day, the hydration product is sparse needle-shaped crystal. The hydration product is a compact network structure at 3 days. From day 7, petaloid crystals appeared. An irregular block structure is formed in 14 days, and the hydration product is gradually compacted. Until 28 days, the structural surface basically tends to be flat. The result shows that GO can promote the generation of petal-shaped crystals, and is beneficial to improving the toughness of the cement-based material. Along with the gradual compaction of structure, characteristics such as compressive strength and rupture strength of cement-based material improve gradually.

Claims (10)

1. The graphene oxide compounded cement mortar is characterized in that cement, water, sand, a water reducing agent and graphene oxide are used as raw materials and are mixed and stirred to form the cement mortar, wherein the cement and the sand are mixed according to a mass ratio of 1:3, the water-cement ratio is 0.35, the doping amount of the graphene oxide is 0.01-0.07 wt% of the mass of cement solids, and the doping amount of the water reducing agent is 0.198-0.306 wt% of the mass of the cement solids.
2. The graphene oxide compounded cement mortar as claimed in claim 1, wherein the cement is portland cement.
3. The graphene oxide compounded cement mortar of claim 1, wherein the water reducing agent is a polycarboxylic acid type water reducing agent.
4. The graphene oxide compounded cement mortar of claim 3, wherein the water reducing agent has a water reducing rate of 25% and an initial solid content of 18%.
5. The graphene oxide compounded cement mortar of claim 1, 3 or 4, wherein the addition of the water reducing agent is increased by 0.018% for every 0.01% increase of the addition of the graphene oxide in the cement mortar.
6. The graphene oxide compounded cement mortar of claim 1, wherein the graphene oxide adopts multilayer graphene oxide powder.
7. The preparation method of the graphene oxide composite cement mortar is characterized in that cement mortar is formed by mixing and stirring cement, water, sand, a water reducing agent and graphene oxide serving as raw materials, wherein the cement and the sand are mixed according to a mass ratio of 1:3, the water-cement ratio is 0.35, the doping amount of the graphene oxide is 0.01-0.07 wt% of the mass of cement solids, and the doping amount of the water reducing agent is 0.198-0.306 wt% of the mass of the cement solids; the preparation process comprises the following steps: firstly, preparing a graphene oxide dispersion liquid, then weighing cement, water, sand, a water reducing agent and the graphene oxide dispersion liquid according to the proportion, then sequentially adding the water, the graphene oxide dispersion liquid and the water reducing agent into a container for stirring, fully mixing to obtain a mixed solution, then placing the cement and the sand into a stirring pot for stirring, standing for 8-12 seconds after the cement and the sand are uniformly stirred, and then pouring the mixed solution into the stirring pot for stirring to obtain the cement mortar.
8. The preparation method of the graphene oxide composite cement mortar as claimed in claim 7, wherein the graphene oxide dispersion liquid is prepared by the following steps: and (2) ultrasonically dispersing a certain amount of graphene oxide powder in a certain amount of deionized water for 15-25min to prepare a graphene oxide dispersion liquid with the concentration of 2 g/L.
9. The preparation method of the graphene oxide composite cement mortar according to claim 7, wherein the cement and the sand are placed in a stirring pot and stirred by a stirrer at 62rpm for 1 min.
10. The method for preparing graphene oxide composite cement mortar according to claim 7, wherein the mixed solution is poured into the stirring pot and then stirred by a stirrer at 62rpm for 2min, and then stirred at 125rpm for 2 min.
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CN111777377A (en) * 2020-07-14 2020-10-16 长沙通建新材料科技有限公司 Graphene oxide thin-layer dry-mixed mortar for accurate building blocks and process thereof
CN112142410A (en) * 2020-09-28 2020-12-29 燕山大学 High-strength high-impermeability multilayer graphene oxide concrete and preparation method thereof
CN112794318A (en) * 2021-01-28 2021-05-14 中国科学院生态环境研究中心 Pipeline lining based on three-dimensional graphene material and preparation method and application thereof
CN112876152A (en) * 2021-03-11 2021-06-01 湖南春天环保建材有限公司 Novel graphene dry-mixed mortar and preparation method thereof
CN114085058A (en) * 2021-11-03 2022-02-25 深圳大学 Graphene oxide composite cement-based cementing material with high chloride ion curing capacity and preparation method thereof
CN115231880A (en) * 2022-09-22 2022-10-25 太原理工大学 Coal series metakaolin-graphene oxide cement mortar composite material and preparation method thereof

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CN111392721A (en) * 2020-03-26 2020-07-10 重庆永固新型建材有限公司 Graphene oxide dispersion liquid and preparation method and application thereof
CN111777377A (en) * 2020-07-14 2020-10-16 长沙通建新材料科技有限公司 Graphene oxide thin-layer dry-mixed mortar for accurate building blocks and process thereof
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CN114085058A (en) * 2021-11-03 2022-02-25 深圳大学 Graphene oxide composite cement-based cementing material with high chloride ion curing capacity and preparation method thereof
CN115231880A (en) * 2022-09-22 2022-10-25 太原理工大学 Coal series metakaolin-graphene oxide cement mortar composite material and preparation method thereof

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