CN112794683B - Waste concrete-based regenerated cementing material and preparation method thereof - Google Patents

Waste concrete-based regenerated cementing material and preparation method thereof Download PDF

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CN112794683B
CN112794683B CN202110041733.XA CN202110041733A CN112794683B CN 112794683 B CN112794683 B CN 112794683B CN 202110041733 A CN202110041733 A CN 202110041733A CN 112794683 B CN112794683 B CN 112794683B
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waste concrete
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cement paste
hardened cement
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CN112794683A (en
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李伟峰
纪小敏
马素花
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Nanjing Tech University
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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
    • 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
    • C04B7/00—Hydraulic cements
    • C04B7/24—Cements from oil shales, residues or waste other than slag
    • 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
    • C04B7/00—Hydraulic cements
    • C04B7/24—Cements from oil shales, residues or waste other than slag
    • C04B7/246—Cements from oil shales, residues or waste other than slag from waste building materials, e.g. waste asbestos-cement products, demolition waste
    • 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
    • C04B7/00—Hydraulic cements
    • C04B7/36—Manufacture of hydraulic cements in general
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding

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  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
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  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Processing Of Solid Wastes (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)

Abstract

The invention discloses a waste concrete-based regenerated cementing material and a preparation method thereof. Crushing hardened cement paste in the waste concrete into fine particles, and then grinding into powder; grinding coal gangue powder into powder; and uniformly mixing the water reducing agent and the retarder, calcining for 2-3 h at 700-800 ℃, taking out, rapidly cooling to room temperature, uniformly mixing with dihydrate gypsum, preparing a water solution from the water reducing agent and the retarder and uniformly stirring with the mixture to obtain the gypsum-containing water reducing agent. The invention compounds the hardened slurry separated from the waste concrete and the coal gangue, and the material has the gelling property again after the heat treatment, and the regenerated gelling material has high strength and good durability, can reduce the waste treatment cost, changes waste into valuable, can protect the environment and save natural resources.

Description

Waste concrete-based regenerated cementing material and preparation method thereof
Technical Field
The invention belongs to the field of building materials, and particularly relates to a regenerated cementing material prepared from hardened cement paste and coal gangue in waste concrete and a preparation method thereof.
Background
At present, resource utilization of waste concrete mainly focuses on two aspects: firstly, the waste concrete is broken and used as a filling material for roadbeds or low-strength products such as building blocks, paving bricks and the like, and nearly 90 percent of the waste concrete is treated in such a way. Secondly, the separated recycled aggregate is used for partially or completely replacing natural aggregate to prepare recycled aggregate concrete, and research shows that: the separated recycled aggregate has high water absorption and slightly poor physical properties due to the fact that old cement mortar is attached to the surface of the recycled aggregate, so that the prepared recycled concrete has the defects of low compressive strength, large elastic modulus, poor durability and the like, and the application range of the recycled concrete is limited. And the fine powder mainly comprising hardened cement mortar which is sieved out cannot be effectively utilized.
In recent years, the heat regeneration of cement mortar in waste concrete is concentrated at home and abroad, hardened cement paste in the waste concrete is separated by a crushing device, and the waste water is excited by calcining at a certain temperatureHydration activity of the mud body, and preparing the regenerated cementing material. But due to C-S-H gel, Ca (OH)2And CaCO3f-CaO is generated in a large amount when decomposed by heat, and Ca (OH) is rapidly formed when the F-CaO contacts water2Not only a large amount of mixing water needs to be consumed. Meanwhile, the reaction of the f-CaO and the water is a rapid exothermic process, the generated heat can accelerate the hydration reaction of other components, the working performance of the regenerated gel material is poor, the strength grade of the regenerated gel material is low, and the regenerated gel material cannot be effectively utilized.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to solve the technical problem of providing a regenerated cementing material prepared by using hardened cement paste and coal gangue in waste concrete aiming at the defects of the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the waste concrete-based regenerated cementing material comprises the following components in parts by weight:
Figure BDA0002896152920000011
Figure BDA0002896152920000021
specifically, the waste hardened cement paste is obtained by crushing hardened cement paste in waste concrete, grinding the crushed hardened cement paste, and calcining the ground hardened cement paste at 700-800 ℃.
Specifically, the calcined coal gangue is obtained by grinding coal gangue and calcining at 700-800 ℃.
Further, the invention also provides a preparation method of the waste concrete-based regenerated cementing material, which comprises the following steps:
(1) crushing hardened cement paste in the waste concrete into fine particles, and then grinding into powder;
(2) grinding coal gangue powder into powder;
(3) uniformly mixing the waste concrete hardened slurry powder obtained in the step (1) with the coal gangue powder obtained in the step (2), calcining at 700-800 ℃ for 2-3 h, taking out, and then quenching to room temperature;
(4) uniformly mixing the calcined product in the step (3) with dihydrate gypsum;
(5) mixing a water reducing agent and a retarder in water to prepare an aqueous solution, and uniformly stirring;
(6) and (4) uniformly stirring the aqueous solution obtained in the step (5) and the mixture obtained in the step (4).
Preferably, in the step (1), the hardened cement paste in the waste concrete is firstly crushed into particles with the particle size of less than or equal to 5mm, and then the particles are ground by a ball mill to powder with the particle size of less than or equal to 100 meshes.
Preferably, in the step (2), the coal gangue is ground to powder with the granularity less than or equal to 100 meshes by a ball mill.
Preferably, in step (3), a mixer is used for mixing and homogenizing before calcination.
Preferably, in the step (4), a proper amount of dihydrate gypsum is added into the calcined product to adjust the setting speed of the regenerated cementing material, the calcined product is uniformly mixed and digested for 2-3 days at the temperature of 20 +/-1 ℃ and the humidity of 99%, the cement slurry containing more CaO becomes pulverized hydroxide with less free water content after absorbing water, and the water-cement ratio of a later-stage cementing system and the early-stage high heat release can be effectively reduced.
In the invention, after the hardened slurry separated from the waste concrete is subjected to heat treatment, the C-S-H gel can be decomposed to generate C with rehydration activity2S, and C-S-H gel, Ca (OH)2And CaCO3The decomposition by heat generates more f-CaO, and a large amount of Ca (OH) is rapidly formed when the F-CaO contacts water2And good excitation conditions can be provided for the calcined coal gangue with the volcanic ash activity. The hardened slurry and coal gangue composite system can reduce the waste treatment cost, change waste into valuable, protect the environment, and the regenerated cementing material has high strength and good durability.
Has the advantages that:
compared with the prior art, the invention has the following advantages: (1) compared with the existing regenerated cementing material, the cementThe raw materials of the regenerated cementing material product are all industrial wastes except the additive, the using amount is up to more than 97 percent, clinker such as cement and the like is not added, the resource utilization of solid wastes such as waste concrete and coal gangue can be realized, the consumption of natural resources is saved, and the environment is protected. (2) After the digestion process, a large amount of CaO absorbs water and is changed into powdered hydroxide with little free water content, thereby not only solving the problems of large early heat release and high water demand caused by high f-CaO content of hardened slurry after heat treatment, but also generating a large amount of Ca (OH) when meeting water2Can also provide good excitation condition (xCa (OH)) for coal gangue with volcanic ash activity2+SiO2+mH2O→xCaO·SiO2·mH2O，yCa(OH)2+Al2O3+mH2O→yCaO·Al2O3·mH2O), improves the hydration performance of the regenerated cementing material, improves the durability and has certain technical feasibility. (3) The method has the advantages of simple operation, low cost, obvious effect, low energy consumption and obvious industrial practical value.
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The foregoing and/or other advantages of the invention will become further apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.
FIG. 1 is a flow chart of the preparation of the regenerated gel material of the present invention.
Detailed Description
The invention will be better understood from the following examples.
In the following examples, the water reducing agents were all high-efficiency water reducing agents of Tanzhou Langpo company, and the retarders were all tartaric acid.
In the following examples, the cement used in the waste hardened cement paste is 52.5 cement.
Example 1:
the composition of the regenerated cementitious material of this example includes:
Figure BDA0002896152920000031
the preparation method of the regenerated gel material of the embodiment comprises the following steps: drying the waste hardened cement paste particles and the coal gangue for 24 hours at 50 ℃, then respectively grinding the waste hardened cement paste particles and the coal gangue into waste hardened cement paste powder with the granularity of less than or equal to 100 meshes and mixing and homogenizing the waste hardened cement paste powder and the coal gangue powder by a mixer; and (3) putting the mixed waste hardened cement slurry powder and coal gangue powder into a muffle furnace, heating to 750 ℃, preserving heat for 2 hours, and then quenching to room temperature by using wind power. The calcined product was mixed with dihydrate gypsum, homogenized by mixing with a blender, and digested in a curing oven at 20 + -1 deg.C and a humidity of 99% for 2 days. Mixing the high-efficiency water reducing agent and the retarder in water to prepare an aqueous solution, uniformly stirring, pouring into a stirrer to be uniformly stirred with the mixture, forming into cubic test blocks of 2cm multiplied by 2cm, and measuring the compressive strength of the regenerated hardened cement paste cementing material neat paste at each age after standard curing for 3d, 7d and 28d, wherein the results are shown in Table 1.
Example 2:
the composition of the regenerated cementitious material of this example includes:
Figure BDA0002896152920000041
the preparation method of the regenerated gel material of the embodiment comprises the following steps: drying the waste hardened cement paste particles and coal gangue at 50 ℃ for 24 hours, then grinding the waste hardened cement paste particles and coal gangue into waste hardened cement paste powder with the granularity less than or equal to 100 meshes, and mixing and homogenizing the waste hardened cement paste powder and the coal gangue powder by a mixer; and (3) putting the mixed waste hardened cement slurry powder and coal gangue powder into a muffle furnace, heating to 750 ℃, preserving heat for 2 hours, and then quenching to room temperature by using wind power. The calcined product was mixed with dihydrate gypsum, homogenized by mixing with a blender, and digested in a curing oven at 20 + -1 deg.C and a humidity of 99% for 2 days. Mixing the high-efficiency water reducing agent and the retarder in water to prepare an aqueous solution, uniformly stirring, pouring into a stirrer to be uniformly stirred with the mixture, forming into cubic test blocks of 2cm multiplied by 2cm, and measuring the compressive strength of the regenerated hardened cement paste cementing material neat paste at each age after standard curing for 3d, 7d and 28d, wherein the results are shown in Table 1.
Example 3:
the composition of the regenerated cementitious material of this example includes:
Figure BDA0002896152920000042
Figure BDA0002896152920000051
the preparation method of the regenerated gel material of the embodiment comprises the following steps: drying the waste hardened cement paste particles and coal gangue at 50 ℃ for 24 hours, then grinding the waste hardened cement paste particles and coal gangue into waste hardened cement paste powder with the granularity less than or equal to 100 meshes, and mixing and homogenizing the waste hardened cement paste powder and the coal gangue powder by a mixer; and (3) putting the mixed waste hardened cement slurry powder and coal gangue powder into a muffle furnace, heating to 750 ℃, preserving heat for 2 hours, and then quenching to room temperature by using wind power. The calcined product was mixed with dihydrate gypsum, homogenized by mixing with a blender, and digested in a curing oven at 20 + -1 deg.C and a humidity of 99% for 2 days. Mixing the high-efficiency water reducing agent and the retarder in water to prepare an aqueous solution, uniformly stirring, pouring the aqueous solution into a stirrer to be uniformly stirred with the mixture, forming into cubic test blocks of 2cm multiplied by 2cm, and measuring the compressive strength of the regenerated hardened cement paste cementing material net slurry at each age after standard curing for 3d, 7d and 28d, wherein the results are shown in table 1.
Comparative example 1:
the composition of the regenerated cementitious material of this example includes:
Figure BDA0002896152920000052
the preparation method of the regenerated gel material of the embodiment comprises the following steps: drying the waste hardened cement paste particles and coal gangue at 50 ℃ for 24 hours, then grinding the waste hardened cement paste particles and coal gangue into waste hardened cement paste powder with the granularity less than or equal to 100 meshes, and mixing and homogenizing the waste hardened cement paste powder and the coal gangue powder by a mixer; and (3) putting the mixed waste hardened cement slurry powder and coal gangue powder into a muffle furnace, heating to 750 ℃, preserving heat for 2 hours, and then quenching to room temperature by using wind power. The calcined product was mixed with dihydrate gypsum, homogenized by mixing with a blender, and digested in a curing oven at 20 + -1 deg.C and a humidity of 99% for 2 days. Mixing the high-efficiency water reducing agent and the retarder in water to prepare an aqueous solution, uniformly stirring, pouring into a stirrer to be uniformly stirred with the mixture, forming into cubic test blocks of 2cm multiplied by 2cm, and measuring the compressive strength of the regenerated hardened cement paste cementing material neat paste at each age after standard curing for 3d, 7d and 28d, wherein the results are shown in Table 1.
Comparative example 2:
0.2 part of water reducing agent and 0.1 part of retarder are dissolved in 40 parts of water to prepare an aqueous solution, the aqueous solution is uniformly stirred, then the aqueous solution is poured into a stirrer to be uniformly stirred with 100 parts of 42.5 parts of cement, a cubic test block with the size of 2cm multiplied by 2cm is formed, after standard curing is carried out for 3d, 7d and 28d, the compressive strength of the hardened cement paste cementing material neat paste at each age is measured, and the results are shown in Table 1.
Comparative example 3:
the composition of the regenerated cementitious material of this example includes:
Figure BDA0002896152920000061
the preparation method of the regenerated gel material of the embodiment comprises the following steps: drying the waste hardened cement paste particles and the coal gangue for 24 hours at 50 ℃, then respectively grinding the waste hardened cement paste particles and the coal gangue into waste hardened cement paste powder with the granularity of less than or equal to 100 meshes and mixing and homogenizing the waste hardened cement paste powder and the coal gangue powder by a mixer; and (3) putting the mixed waste hardened cement slurry powder and coal gangue powder into a muffle furnace, heating to 750 ℃, preserving heat for 2 hours, and then quenching to room temperature by using wind power. The calcined product was mixed with dihydrate gypsum (without digestion). Mixing the high-efficiency water reducing agent and the retarder in water to prepare an aqueous solution, uniformly stirring, pouring into a stirrer to be uniformly stirred with the mixture, forming into cubic test blocks of 2cm multiplied by 2cm, and measuring the compressive strength of the regenerated hardened cement paste cementing material neat paste at each age after standard curing for 3d, 7d and 28d, wherein the results are shown in Table 1.
Comparative example 4:
the composition of the regenerated cementitious material of this example includes:
Figure BDA0002896152920000062
Figure BDA0002896152920000071
the preparation method of the regenerated gel material of the embodiment comprises the following steps: the waste hardened cement paste is dried for 24 hours at 50 ℃, then ground into waste hardened cement paste powder with the granularity less than or equal to 100 meshes, the hardened cement paste powder is put into a muffle furnace to be heated to 750 ℃, the temperature is kept for 2 hours, and then the hardened cement paste powder is rapidly cooled to room temperature by wind power. Mixing a high-efficiency water reducing agent and a retarder in water to prepare an aqueous solution, uniformly stirring, pouring the aqueous solution into a stirrer to be uniformly stirred with the calcined waste hardened cement paste powder, forming into cubic test blocks of 2cm multiplied by 2cm, and measuring the compressive strength of the regenerated hardened cement paste cementing material net slurry at each age after standard curing for 3d, 7d and 28d, wherein the results are shown in table 1.
Comparative example 5:
the composition of the regenerated cementitious material of this example includes:
Figure BDA0002896152920000072
the preparation method of the regenerated gel material of the embodiment comprises the following steps: drying coal gangue at 50 deg.C for 24 hr, grinding into powder with granularity less than or equal to 100 meshes, heating to 750 deg.C in muffle furnace, holding for 2 hr, and quenching to room temperature by wind power. Mixing a high-efficiency water reducing agent and a retarder in water to prepare an aqueous solution, uniformly stirring, pouring into a stirrer to be uniformly stirred with the calcined gangue powder, forming into cubic test blocks of 2cm multiplied by 2cm, and measuring the compressive strength of the regenerated hardened cement paste cementing material neat paste at each age after standard curing for 3d, 7d and 28d, wherein the results are shown in Table 1.
Comparative example 6:
the regenerated cementitious material composition of the present example includes:
Figure BDA0002896152920000073
Figure BDA0002896152920000081
the preparation method of the regenerated gel material of the embodiment comprises the following steps: drying the waste hardened cement paste particles for 90min at 450 ℃, and then respectively grinding to obtain the waste hardened cement paste particles with the specific surface area of 365m2Per Kg of waste hardened cement paste powder in powder form; pouring the powdery waste hardened cement paste and the fly ash into a stirrer to be dry-mixed for 3min to obtain a dry-mixed material; mixing and stirring sodium hydroxide, water glass and water to completely dissolve the sodium hydroxide to prepare diluted water glass; pouring the diluted water glass into a stirrer to be mixed with the dry mixture for stirring for 30s, then pouring the water reducing agent and the sodium phosphate into the stirrer to be continuously stirred uniformly to form cubic test blocks of 2cm multiplied by 2cm, and after standard curing for 3d, 7d and 28d, measuring the compressive strength of the regenerated and hardened cement paste cementing material neat paste at each age, wherein the results are shown in Table 1.
TABLE 1
Group of 3d 7d 28d
Example 1 18.91 47.85 57.89
Example 2 15.89 44.33 52.75
Example 3 11.84 32.73 49.92
Comparative example 1 3.03 20.56 41.13
Comparative example 2 35.27 40.53 43.25
Comparative example 3 9.78 23.98 32.61
Comparative example 4 7.14 7.96 9.12
Comparative example 5 - - -
Comparative example 6 14.22 21.57 35.88
The data in the table show that the technical indexes of the regenerated cementing material prepared in each embodiment meet the design requirements and have good mechanical properties, which shows that the regenerated cementing material provided by the invention can completely replace cement or other traditional mineral admixtures, not only saves natural resources and protects the environment, but also provides a new idea for preparing mineral admixtures from waste concrete in the future, and has remarkable social and economic benefits.
Comparing examples 1-3 with comparative example 1, it can be seen that the ratio of the calcined waste hardened cement paste to the calcined coal gangue is more appropriate, and the increase of the calcined coal gangue is unfavorable for hydration and strength.
Comparing the examples with the comparative example 2, it can be seen that the early strength difference of the regenerated hardened cement paste cementing material prepared by the invention is more obvious than that of 42.5 cement, but with the prolonging of the hydration age, the pozzolanic activity in the regenerated hardened cement paste cementing material is excited, the later hydration strength is obviously improved, and the strength of 28d is obviously higher than that of 42.5 cement.
Comparing the examples with comparative example 3, the hardened slurry, which had been heat treated to have a large amount of CaO, was digested to produce powdery hydroxides (CaO + H) having a low free water content by adsorbing moisture from the moisture2O→Ca(OH)2) The problems of high water demand and high early heat release caused by high CaO content can be solved. The calcined coal gangue has a certain pozzolanic activity, amorphous or glassy SiO2And active Al2O3Can react with CaO under normal temperature and in the presence of water to generate hydrate with hydraulic gelation ability. Excitation principle: xCa (OH)2+SiO2+mH2O→xCaO·SiO2·mH2O，yCa(OH)2+Al2O3+mH2O→yCaO·Al2O3·mH2And O. The above reaction shows that CaO in the dehydrated phase of the cement paste provides good excitation conditions for the substances with pozzolanic activity. It can also be seen from table 1 that the performance of the composite system after digestion is significantly improved.
Comparing the examples with comparative examples 4 and 5, it is known that when the waste hardened cement paste is separately heat-treated to prepare the regenerated cement, the early water demand is large, the early heat release is high, the working performance is affected, and the strength is low. When the coal gangue is subjected to heat treatment alone to prepare the regenerated cementing material, the coal gangue can not be demoulded after being maintained for 1d, and the coal gangue still has no strength after a plurality of days. The two are used for preparing a composite system, and the high water demand and high early heat release are solved through the digestion process, and the strength performance of the regenerated cementing material is greatly improved.
Comparing the regenerated cementing material prepared in the embodiment with the regenerated cementing material prepared in the comparative example 6, the comparative example 6 is that the waste hardened cement slurry is dried at 450 ℃ to change the hydration product in the hardened slurry into a dehydrated product, and then the silicon-oxygen tetrahedron and aluminum-oxygen octahedron are depolymerized by the alkaline excitant such as sodium hydroxide, sodium silicate sodium glass and the like, and the structure is recombined to form a new cementitious product such as hydrated calcium aluminosilicate. In the invention, after the waste hardened cement paste is subjected to heat treatment at 800 ℃ and 700 ℃, compared with 450 ℃ in the comparative example 6, C-S-H gel in the dehydration phase of the cement paste can be thermally decomposed to generate active C2S, when the calcium silicate hydrate is contacted with water, the calcium silicate hydrate has the ability of hydration hardening again to generate calcium silicate hydrate. And the coal gangue calcined at the temperature of 700-800 ℃ is converted from kaolin into metakaolin with volcanic ash activity, and the CaO in the waste hardened cement slurry after heat treatment is converted into Ca (OH) during the digestion and contact with water of the mixture2Thereby exciting the volcanic ash effect of the calcined coal gangue. Excitation principle: xCa (OH)2+SiO2+mH2O→xCaO·SiO2·mH2O，yCa(OH)2+Al2O3+mH2O→yCaO·Al2O3·mH2And O, so that the prepared regenerated cementing material has better strength performance, and particularly has obvious later strength advantage.
The invention provides a concept and a method for preparing a waste concrete-based regenerated cementing material, and a method and a device for realizing the technical scheme, and the method and the device are more than one, and the above description is only a preferred embodiment of the invention, and it should be noted that, for a person skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the invention, and the improvements and decorations should be regarded as the protection scope of the invention. All the components not specified in the present embodiment can be realized by the prior art.

Claims (6)

1. The waste concrete-based regenerated cementing material is characterized by comprising the following components in parts by weight:
60-80 parts of waste hardened cement paste is calcined,
20-40 parts of calcined coal gangue,
1-4 parts of dihydrate gypsum,
0.1 to 0.5 portion of water reducing agent,
0.1 to 0.3 portion of retarder,
30-50 parts of water;
the waste concrete-based regenerated cementing material is prepared by the following method:
(1) crushing hardened cement paste in the waste concrete into fine particles, and then grinding into powder;
(2) grinding coal gangue powder into powder;
(3) uniformly mixing the waste concrete hardened slurry powder obtained in the step (1) with the coal gangue powder obtained in the step (2), calcining at 700-800 ℃ for 2-3 h, taking out, and then quenching to room temperature;
(4) uniformly mixing the calcined product in the step (3) with dihydrate gypsum, and digesting for 2-3 days at the temperature of 20 +/-1 ℃ and the humidity of 99%;
(5) mixing a water reducing agent and a retarder in water to prepare an aqueous solution, and uniformly stirring;
(6) and (5) uniformly stirring the aqueous solution obtained in the step (5) and the mixture obtained in the step (4).
2. The waste concrete-based regenerated cementitious material as claimed in claim 1, wherein the waste hardened cement paste is obtained by crushing the hardened cement paste in waste concrete, grinding the crushed hardened cement paste, and calcining the ground hardened cement paste at 700-800 ℃.
3. The waste concrete-based regenerated cementing material according to claim 1, wherein the calcined coal gangue is obtained by grinding coal gangue and then calcining at 700-800 ℃.
4. The waste concrete-based regenerated cementitious material as claimed in claim 1, wherein in the step (1), the hardened cement paste in the waste concrete is firstly crushed into particles with the particle size of less than or equal to 5mm, and then the particles are ground into powder with the particle size of less than or equal to 100 meshes by using a ball mill.
5. The waste concrete-based regenerated cementing material of claim 1, wherein in the step (2), the coal gangue is ground into powder with the granularity less than or equal to 100 meshes by a ball mill.
6. The waste concrete-based recycled cementitious material of claim 1, characterised in that in step (3), a mixer is used for mixing and homogenisation before calcination.
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