CN112811873B - Recycled aggregate concrete and preparation process thereof - Google Patents
Recycled aggregate concrete and preparation process thereof Download PDFInfo
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- CN112811873B CN112811873B CN202110212013.5A CN202110212013A CN112811873B CN 112811873 B CN112811873 B CN 112811873B CN 202110212013 A CN202110212013 A CN 202110212013A CN 112811873 B CN112811873 B CN 112811873B
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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
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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
- 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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Abstract
The application relates to the field of concrete, and particularly discloses recycled aggregate concrete and a preparation process thereof, wherein the recycled aggregate concrete is mainly prepared from the following raw materials: 20-25 parts of cement; 30-40 parts of modified recycled coarse aggregate; 20-30 parts of modified recycled fine aggregate; 5-7 parts of modified calcium aluminate; 0.3-0.5 part of additive; 8-12 parts of water; the modified recycled coarse aggregate and the modified recycled fine aggregate are obtained by respectively modifying the recycled coarse aggregate and the recycled fine aggregate through epoxy emulsion, and the modified calcium aluminate is obtained by modifying calcium aluminate micro powder through polyether amine. The process comprises the following steps: respectively modifying the recycled coarse aggregate, the recycled fine aggregate and the calcium aluminate at a lower temperature, then mixing and curing the modified recycled coarse aggregate, the recycled fine aggregate and the calcium aluminate at a higher temperature, and repairing the damaged part on the surface of the recycled aggregate; finally, mixing the recycled aggregate concrete with cement, water and an additive to obtain the recycled aggregate concrete. The deep ploughing aggregate concrete prepared by the method has higher strength after solidification and wider application range.
Description
Technical Field
The application relates to the technical field of concrete, in particular to recycled aggregate concrete and a preparation process thereof.
Background
At present, in the development and construction of cities, a large amount of construction waste materials, such as concrete waste materials generated after buildings are removed, are generated. These waste materials are now usually discarded directly, thus easily causing great damage to the environment and causing a serious waste of resources. Therefore, many recycled aggregate concrete appears in the market at present, and the building waste is used as part of the aggregate, so that the building waste can be fully recycled, the utilization rate of resources is improved, and the recycled aggregate concrete has a good development prospect.
The recycled aggregate concrete disclosed in the Chinese patent application with the application number of CN200910070564.1 comprises the following raw materials of 4-20% by weight of cement, 0-35% by weight of recycled fine aggregate, 0-46% by weight of recycled coarse aggregate, 1-8% by weight of admixture, 1.5-2.5% by weight of pumping agent for concrete and the balance of water.
However, as the recycled aggregate is formed by crushing concrete waste, damage and cracks are easily generated on the surface of the recycled aggregate in the crushing process, so that compared with common concrete, the strength of the recycled aggregate concrete is lower, and the application scene is limited.
Disclosure of Invention
In order to improve the strength of the recycled aggregate concrete, the application provides the recycled aggregate concrete and a preparation process thereof.
In a first aspect, the present application provides a recycled aggregate concrete, which adopts the following technical scheme:
the recycled aggregate concrete is mainly prepared from the following raw materials:
20-25 parts of cement;
30-40 parts of modified recycled coarse aggregate;
20-30 parts of modified recycled fine aggregate;
5-7 parts of modified calcium aluminate;
0.3-0.5 part of additive;
8-12 parts of water;
the modified recycled coarse aggregate and the modified recycled fine aggregate are obtained by respectively modifying the recycled coarse aggregate and the recycled fine aggregate through epoxy emulsion, and the modified calcium aluminate is obtained by modifying calcium aluminate micro powder through polyether amine.
By adopting the technical scheme, the raw materials, besides conventional cement, additives and water, also contain the calcium aluminate modified by polyether amine, and the recycled coarse aggregate and the recycled fine aggregate are modified by using the epoxy emulsion. After modification, in the mixing process, as the polyether amine and the epoxy emulsion are crosslinked, aluminate is gradually attached to the surfaces of the regenerated coarse aggregate and the regenerated fine aggregate and enters damaged parts of the regenerated coarse aggregate and the regenerated fine aggregate, and after the epoxy emulsion and the polyether amine are crosslinked and cured, calcium aluminate is solidified at the damaged parts of the surfaces of the regenerated aggregates to repair and reinforce the damaged parts, so that the strength of the regenerated aggregate concrete is improved.
Preferably, the raw material also comprises 2-3 parts of diatomite by mass.
By adopting the technical scheme, on one hand, the diatomite has higher impact strength and tensile strength and good light soft internal wear, so that the strength of the concrete can be increased by adding the diatomite into the raw materials. On the other hand, the diatomite has the advantages of large porosity, strong absorptivity, stable chemical property, wear resistance and the like, and is added in the mixing process, when the epoxy emulsion on the surfaces of the modified recycled coarse aggregate and the modified recycled fine aggregate is crosslinked and consolidated with the polyether amine on the surface of the modified calcium aluminate, the diatomite can be further attached to the surface of the aggregate, so that the modified recycled aggregates are prevented from being consolidated with each other, the aggregates are distributed in the concrete more uniformly, and the stability of the structure is improved.
Preferably, the epoxy value of the epoxy emulsion used for modifying the recycled coarse aggregate and the recycled fine aggregate is 0.4 to 0.45.
By adopting the technical scheme, the epoxy emulsion with a higher epoxy value of 0.4-0.45 is used, so that the fine calcium aluminate is favorably attached to the damaged part on the surface of the recycled aggregate, and the calcium aluminate is favorably crosslinked and consolidated with the polyether amine on the surface of the calcium aluminate.
Preferably, the particle size of the dispersed phase in the epoxy emulsion used for modifying the recycled coarse aggregate and the recycled fine aggregate is 3 to 5 μm.
By adopting the technical scheme, the epoxy emulsion with smaller dispersed phase particle size is adopted, so that the epoxy emulsion can enter finer damaged parts on the surface of the recycled aggregate, and the finer damage can be reinforced, and the recycled aggregate concrete has better strength.
Preferably, the amine number of the polyetheramine used for modifying calcium aluminate is 450-500.
By adopting the technical scheme, the polyether amine with the amine value of 450-500 has higher fluidity, and is beneficial to fully combining with calcium aluminate.
Preferably, the particle size of the recycled coarse aggregate is 25-35mm, and the particle size of the recycled fine aggregate is 2.5-2.8 mm.
By adopting the technical scheme, the recycled coarse aggregate with the thickness of 25-35mm and the recycled fine aggregate with the thickness of 2.5-2.8mm can achieve better modification effect, and the modified coarse aggregate and the modified fine aggregate have better strength.
In a second aspect, the application provides a preparation process of recycled aggregate concrete, which adopts the following technical scheme:
the method comprises the following process steps:
s1: aggregate modification: respectively soaking the regenerated coarse aggregate and the regenerated fine aggregate in the epoxy emulsion, controlling the temperature to be 3-5 ℃, stirring and mixing for 10-15min, and then sieving to respectively obtain modified regenerated coarse aggregate and modified regenerated fine aggregate;
s2: modification of calcium aluminate: soaking calcium aluminate in polyetheramine, mixing and stirring for 25-30min, filtering, centrifuging and throwing off excessive polyetheramine on the surface to obtain modified calcium aluminate;
s3: uniformly mixing the modified recycled coarse aggregate and the modified recycled fine aggregate newly prepared in the step S1, adding the modified calcium aluminate newly prepared in the step S2 at the stirring speed of 150-200r/min for 6-8 times, wherein the adding interval is 5-8min each time, after the modified calcium aluminate is completely added, adding diatomite, and continuously mixing the mixture at the temperature of 45-50 ℃ at the stirring speed of 80-100r/min for 1.5-2h to obtain an aggregate mixture;
s4: and uniformly mixing the aggregate mixture, the cement, the water and the additive to obtain the recycled aggregate concrete.
By adopting the technical scheme, the steps S1 and S2 are the steps of modifying the recycled aggregate and the calcium aluminate, the step S1 is modified at low temperature, consolidation of epoxy emulsion in the modification process can be reduced, and the step S2 is centrifuged after filtration, so that only polyether amine with the action amount is attached to the surface of the calcium aluminate, and the calcium aluminate can be prevented from being excessively aggregated on the surface of the recycled aggregate due to the excessive incorporation amount of polyether amine in the subsequent mixing process. After the modification is finished, the calcium aluminate is mixed through the process of the step S3, the calcium aluminate is added for multiple times, so that the calcium aluminate can be more uniformly dispersed and attached to the surface of the recycled aggregate, after the calcium aluminate is added, the calcium aluminate is continuously mixed at high temperature and stirred, the calcium aluminate can be solidified on the surface of the recycled aggregate in the process, the damaged part of the surface of the recycled aggregate can be repaired, and the low-speed stirring is kept, so that the bonding between the recycled aggregates can be prevented. And finally, preparing the aggregate mixture into recycled aggregate concrete through the step S4 to obtain a finished product.
Preferably, in step S2, the calcium aluminate is sonicated during the soaking with the polyetheramine, and the frequency of the sonication is controlled to 20 to 23kHz during the sonication.
By adopting the technical scheme, the calcium aluminate and the polyether amine can be more fully combined through ultrasonic treatment, the polyether amine can be more effectively and comprehensively attached to the surface of the calcium aluminate, the modification effect is improved, and the strength of the recycled aggregate concrete is improved.
In summary, the present application includes at least one of the following beneficial technical effects:
1. the application provides a recycled aggregate concrete, through to using epoxy emulsion to modify the recycled aggregate to add by the modified calcium aluminate of polyetheramine, can repair the damage on recycled aggregate surface, improve the intensity of recycled aggregate, thereby improve the intensity of recycled aggregate concrete.
2. According to the preferable scheme of the application, the diatomite is added, so that the strength of the concrete can be further improved.
3. In the preferred scheme of the application, various process parameters of the epoxy emulsion and the polyether amine are provided, so that the strength of the recycled aggregate concrete is further improved.
4. The application also provides a preparation process of the recycled aggregate concrete, which can more effectively modify recycled coarse aggregate, recycled fine aggregate and calcium aluminate, and can ensure that the calcium aluminate is uniformly attached to the surface of the aggregate and is fully solidified, so that the recycled aggregate has better strength.
5. In the preferred embodiment of the present application, the modification of the calcium polyphosphate by ultrasonic treatment can make the polyether amine more stably combined with the calcium aluminate.
Detailed Description
Examples
Example 1: a recycled aggregate concrete, which is prepared by mixing a recycled aggregate,
the raw materials are as follows: 20kg of cement, 30kg of modified recycled coarse aggregate, 20kg of modified recycled fine aggregate, 5kg of modified calcium aluminate, 0.3kg of additive and 8kg of water. The cement is Portland cement P.I 42.5R; the modified recycled coarse aggregate and the modified recycled fine aggregate are obtained by respectively modifying the recycled coarse aggregate and the recycled fine aggregate through epoxy emulsion; the modified calcium aluminate is obtained by modifying calcium aluminate micro powder by polyether amine; the additive is naphthalene sulfonate water reducing agent. The amounts of the respective components added, the epoxy value of the epoxy emulsion for modification and the particle diameter of the dispersed phase, the amine value of the polyetheramine for modification, the particle diameter of the recycled coarse aggregate and the particle diameter of the recycled fine aggregate are shown in table 1 below.
The preparation process comprises the following steps:
s1: aggregate modification: respectively adding epoxy emulsion into two stirring barrels, respectively soaking the regenerated coarse aggregate and the regenerated fine aggregate into the epoxy emulsion, controlling the temperature to be 3 ℃, selecting at a stirring speed of 60r/min, stirring and mixing for 13min, and then sieving to respectively obtain modified regenerated coarse aggregate and modified regenerated fine aggregate;
s2: modification of calcium aluminate: adding polyetheramine into a stirring barrel, soaking the calcium aluminate into the polyetheramine, mixing and stirring for 25min at the stirring speed of 60r/min, filtering, centrifuging for 1.5min in a centrifuge at 800r/min, and centrifuging to remove the excessive polyetheramine on the surface to obtain modified calcium aluminate;
s3: uniformly mixing the modified recycled coarse aggregate and the modified recycled fine aggregate which are newly prepared in the step S1, adding the modified calcium aluminate which is newly prepared in the step S2 for 7 times at a stirring speed of 180r/min, wherein the adding interval is 6min each time, and after the modified calcium aluminate is completely added, continuously mixing the mixture at the temperature of 45 ℃ for 1.5h at a stirring speed of 80r/min to obtain an aggregate mixture;
s4: and uniformly mixing the aggregate mixture, the cement, the water and the additive to obtain the recycled aggregate concrete.
Example 2: a recycled aggregate concrete, which is prepared by mixing a recycled aggregate,
the difference from example 1 is that the amounts of the components are different, and the specific amounts are shown in table 1 below.
Examples 3 to 4: a recycled aggregate concrete, which is characterized in that,
the difference from example 1 is that diatomite is also added into the raw materials, and the specific dosage of each component is shown in the following table 1.
Step S3 becomes: and (2) uniformly mixing the modified recycled coarse aggregate and the modified recycled fine aggregate newly prepared in the step (S1), adding the modified calcium aluminate newly prepared in the step (S2) at 7 times at a stirring speed of 180r/min, wherein the addition interval is 6min each time, adding the kieselguhr into the mixture after the modified calcium aluminate is completely added, and continuously mixing the mixture at the temperature of 45 ℃ for 1.5h at the stirring speed of 80r/min to obtain an aggregate mixture.
Examples 5 to 6: a recycled aggregate concrete, which is prepared by mixing a recycled aggregate,
the difference from example 1 is that the epoxy value of the epoxy emulsion used is different, as shown in Table 1 below.
Examples 7 to 8: a recycled aggregate concrete, which is prepared by mixing a recycled aggregate,
the difference from example 1 is that the dispersed phase particle size of the epoxy emulsion used is different, and the specific parameters are shown in table 1 below.
Examples 9 to 10: a recycled aggregate concrete, which is characterized in that,
the difference from example 1 is that the amine number of the polyetheramine used is different, the specific parameters being shown in table 1 below.
Examples 11 to 12: a recycled aggregate concrete, which is prepared by mixing a recycled aggregate,
the difference from example 1 is that the recycled coarse aggregate and the recycled fine aggregate used have different particle sizes, and the specific parameters are shown in table 1 below.
Example 13: a recycled aggregate concrete, which is prepared by mixing a recycled aggregate,
the difference from example 1 is that in step S2, calcium aluminate is sonicated during the soaking with polyetheramine. The amounts and parameters of the components are shown in table 1 below.
The specific process comprises the following steps:
s2: modification of calcium aluminate: adding polyetheramine into a stirring barrel, soaking the calcium aluminate into the polyetheramine, mixing and stirring for 25min at a stirring speed of 60r/min, and carrying out ultrasonic treatment on the calcium aluminate in the soaking and stirring processes, wherein the frequency of the used ultrasonic wave is 20kHz, and the power of the ultrasonic wave is 350W. And (4) centrifuging for 1.5min in a centrifuge of 800r/min after filtering, and centrifuging to remove the excessive polyether amine on the surface to obtain the modified calcium aluminate.
Table 1: EXAMPLES 1-13 amounts of Components and parameters of Components
Comparative example
Comparative example 1: a recycled aggregate concrete comprises the following raw materials: 25kg of cement, 20kg of recycled fine aggregate, 25kg of recycled coarse aggregate, 3kg of admixture, 0.5kg of concrete pumping aid and 26.5kg of water. The admixture is a 1:1 mixture of fly ash and granulated blast furnace slag powder, the cement is P.I 42.5R portland cement, the particle size of the recycled fine aggregate is 3mm, and the particle size of the recycled coarse aggregate is 40 mm.
The preparation process comprises the following steps: and stirring and mixing the cement, the recycled fine aggregate, the recycled coarse aggregate, the admixture, the concrete pumping agent and water in a stirring barrel for 3min to obtain the recycled aggregate concrete.
Comparative example 2: a recycled aggregate concrete, which is prepared by mixing a recycled aggregate,
the difference from example 1 is that no modified calcium aluminate is added to the raw material. The raw materials of the components are shown in the following table 2.
The preparation process comprises the following steps:
s1: aggregate modification: respectively adding epoxy emulsion into two stirring barrels, respectively soaking the regenerated coarse aggregate and the regenerated fine aggregate into the epoxy emulsion, controlling the temperature to be 3 ℃, selecting at a stirring speed of 60r/min, stirring and mixing for 13min, and then sieving to respectively obtain modified regenerated coarse aggregate and modified regenerated fine aggregate;
s2: stirring the modified recycled coarse aggregate and the modified recycled fine aggregate newly prepared in the step S1 at the temperature of 45 ℃ for 1.5h at the stirring speed of 80r/min to obtain an aggregate mixture;
s4: and uniformly mixing the aggregate mixture, the cement, the water and the additive to obtain the recycled aggregate concrete.
Comparative example 3: a recycled aggregate concrete, which is prepared by mixing a recycled aggregate,
the difference from example 1 is that ordinary calcium aluminate is used as a raw material without modifying calcium aluminate. The raw materials of the components are shown in the following table 2.
The preparation process comprises the following steps:
s1: aggregate modification: respectively adding epoxy emulsion into two stirring barrels, respectively soaking the regenerated coarse aggregate and the regenerated fine aggregate into the epoxy emulsion, controlling the temperature to be 3 ℃, selecting at a stirring speed of 60r/min, stirring and mixing for 13min, and then sieving to respectively obtain modified regenerated coarse aggregate and modified regenerated fine aggregate;
s2: uniformly mixing the modified recycled coarse aggregate and the modified recycled fine aggregate newly prepared in the step S1, adding calcium aluminate 7 times at a stirring speed of 180r/min, wherein the interval of each addition is 6min, and after the calcium aluminate is completely added, continuously mixing the mixture at the temperature of 45 ℃ for 1.5h at a stirring speed of 80r/min to obtain an aggregate mixture;
s4: and uniformly mixing the aggregate mixture, the cement, the water and the additive to obtain the recycled aggregate concrete.
Comparative example 4: a recycled aggregate concrete, which is prepared by mixing a recycled aggregate,
the difference from example 1 is that the recycled coarse aggregate, the recycled fine aggregate and the calcium aluminate were not modified, and the ordinary recycled coarse aggregate, the ordinary recycled fine aggregate and the ordinary calcium aluminate were used as raw materials. The raw materials of the components are shown in the following table 2.
The preparation process comprises the following steps: and uniformly mixing the recycled coarse aggregate, the recycled fine aggregate, the calcium aluminate, the cement, the water and the additive to obtain the recycled aggregate concrete.
Table 2: comparative examples 2-4 amounts of each component
Performance test because this application focus on improving the intensity of recycled aggregate concrete, therefore mainly follow intensity convenience and carry out the test.
The test name is: strength test of recycled aggregate concrete
Test subjects: examples 1-13 and comparative examples 1-4.
Sample preparation: according to the national standard GB/T50081-2019, the concrete prepared in the examples 1-13 and the concrete prepared in the comparative examples 1-4 are respectively prepared into two test pieces with the side length of 150mm multiplied by 150mm and 150mm multiplied by 600mm in a mould, the two test pieces are cured and cured for 28d in an environment with the humidity of 95% at the temperature of 20 ℃ to obtain concrete test pieces, and the test pieces of the examples 1-13 and the comparative examples 1-4 are sequentially labeled as test samples 1-13 and comparative samples 1-4.
Test equipment: the CTM2100 microcomputer control testing machine comprises the following testing steps: the compressive strength f was measured according to the national standard GB/T50081-2019 using test and control samples of 150mm x 150mmccAnd the flexural strength f was measured using each of the test specimen and the control specimen of 150 mm. times.150 mm. times.600 mmfThe test results are shown in table 3 below.
Table 3: compressive strengths of test samples 1 to 13 and control samples 1 to 4Degree fccAnd flexural strength ff(MPa)
Referring to the test results in table 3, the following test analysis can be obtained.
Comparing the data of test samples 1-2 and control sample 1 in Table 3, it can be seen that the compressive strength and the flexural strength of control sample 1 are much lower than those of test samples 1-2. It can be illustrated that the strength of the recycled aggregate concrete prepared in examples 1-2 is higher than that of comparative example 1, because the modified recycled coarse aggregate, the modified recycled fine aggregate and the modified calcium aluminate are used in examples 1-2, and after modification, the aluminate gradually adheres to the surfaces of the recycled coarse aggregate and the recycled fine aggregate and enters the damaged parts of the recycled coarse aggregate and the recycled fine aggregate because the polyether amine is crosslinked with the epoxy emulsion during mixing, and after the epoxy emulsion and the polyether amine are crosslinked and cured, the calcium aluminate is solidified on the damaged parts of the surfaces of the recycled aggregate, thereby repairing and reinforcing the damaged parts, and improving the strength of the recycled aggregate concrete.
Comparing the data of test samples 1-2 and control samples 2-4 in Table 3, it can be seen that the compressive strength and the flexural strength of control samples 2-4 are much lower than those of test samples 1-2. The effects of the modified recycled coarse aggregate, the modified recycled fine aggregate and the modified calcium aluminate in the direction of improving the strength of the concrete can be further explained by combining the previous analysis.
Comparing the data of test samples 1-2 and test samples 3-4 in Table 3, it can be seen that both the compressive strength and the flexural strength of test samples 1-2 are lower than those of test samples 3-4. This indicates that the strength of the recycled aggregate concrete prepared in examples 3 to 4 is higher than that of examples 1 to 2. This is because, in examples 3 to 4, the diatomaceous earth is added, and when the epoxy emulsion on the surface of the modified recycled coarse aggregate and the modified recycled fine aggregate is crosslinked and consolidated with the polyetheramine on the surface of the modified calcium aluminate, the diatomaceous earth can be further attached to the surface of the aggregate, thereby preventing the modified recycled aggregates from being consolidated with each other, and enabling the aggregates to be more uniformly distributed in the concrete, thereby improving the stability of the structure.
Comparing the data of test samples 1-2 and test samples 5-6 in Table 3, it can be seen that both the compressive strength and the flexural strength of test samples 1-2 are lower than those of test samples 5-6. This indicates that the strength of the recycled aggregate concrete prepared in examples 5 to 6 was higher than that of examples 1 to 2. Thus, it can be seen that the epoxy values of the epoxy emulsions used for modifying recycled aggregate in examples 5 to 6 are in a more preferable range. This is because, when the epoxy value is too small, the molecular weight of the epoxy resin becomes too large and the epoxy group content becomes too small, so that the binding ability with the modified calcium aluminate after curing is reduced. When the epoxy value is too large, the epoxy group content is too large, so that the aggregates are liable to implode or adhere to each other during consolidation, which affects the uniformity of the consolidated aggregates and the strength of the recycled aggregates.
Comparing the data of test samples 1-2 and 7-8 in Table 3, it can be seen that both the compressive strength and the flexural strength of test samples 1-2 are lower than those of test samples 7-8. This indicates that the strength of the recycled aggregate concrete obtained in examples 7 to 8 is higher than that of examples 1 to 2. This can therefore illustrate the range of parameters for the particle size of the dispersed phase of the epoxy emulsions used to modify recycled aggregate in examples 7-8 to be more optimal. This is because when the particle size of the dispersed phase of the epoxy emulsion is too large, the colloidal particles are not easily introduced into the relatively fine cracks on the surface of the recycled aggregate, and the repairing effect is reduced. When the particle size of the dispersed phase of the epoxy emulsion is too small, implosion is easily generated in the same way, and the uniformity of the modified calcium aluminate on the surface of the recycled aggregate is influenced.
Comparing the data of test samples 1-2 and test samples 9-10 in Table 3, it can be seen that both the compressive strength and the flexural strength of test samples 1-2 are lower than those of test samples 9-10. This indicates that the strength of the recycled aggregate concrete obtained in examples 9 to 10 is higher than that of examples 1 to 2. It can thus be shown that the amine number of the polyetheramines used in examples 9 to 10 for modifying calcium aluminate is a more preferred parameter range. This is because, when the amine value is too large, the modified calcium aluminate is likely to cause implosion on the surface of the recycled aggregate. When the amine value is too small, on one hand, the fluidity of the polyether amine is too small, so that the polyether amine is not beneficial to modifying calcium aluminate, and on the other hand, because the amine value is too small, the consolidation capability of the calcium aluminate on the surface of the recycled aggregate is reduced, so that the strength of the aggregate structure is influenced.
Comparing the data of test samples 1-2 and test samples 11-12 in Table 3, it can be seen that both the compressive strength and the flexural strength of test samples 1-2 are lower than those of test samples 11-12. This indicates that the strength of the recycled aggregate concrete prepared in examples 11 to 12 is higher than that of examples 1 to 2. This indicates that the particle diameters of the recycled coarse aggregate and the recycled fine aggregate used in examples 11 to 12 are more preferable parameter ranges. This is because, in the first aspect, only when coarse aggregates and fine aggregates of appropriate particle diameters are blended, high-strength concrete can be produced; on the other hand, in the crushing process, the aggregates with different particle sizes have different crushing strengths, so that the damage degrees of the surfaces of the aggregates are different, and the aggregates with the proper particle sizes are selected, so that the damage of the surfaces of the aggregates can be repaired more conveniently through the epoxy emulsion and the modified calcium aluminate.
Comparing the data of test samples 1-2 and test sample 13 in Table 3, it can be seen that both the compressive strength and the flexural strength of test samples 1-2 are lower than that of test sample 13. This indicates that the strength of the recycled aggregate concrete prepared in example 13 is higher than that of examples 1 to 2. This is because the ultrasonic treatment is used in the modification process of calcium aluminate in example 13, which can make the calcium aluminate and the polyetheramine more sufficiently combine, and the polyetheramine more effectively and completely adheres to the surface of the calcium aluminate, thereby improving the modification effect and improving the strength of the recycled aggregate concrete.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.
Claims (6)
1. A recycled aggregate concrete is characterized in that: the compound is mainly prepared from the following raw materials:
20-25 parts of cement;
30-40 parts of modified recycled coarse aggregate;
20-30 parts of modified recycled fine aggregate;
5-7 parts of modified calcium aluminate;
0.3-0.5 part of additive;
8-12 parts of water;
2-3 parts of diatomite;
the modified recycled coarse aggregate and the modified recycled fine aggregate are respectively obtained by modifying recycled coarse aggregate and recycled fine aggregate through epoxy emulsion, and the modified calcium aluminate is obtained by modifying calcium aluminate micro powder through polyether amine;
the preparation process of the recycled aggregate concrete comprises the following process steps:
s1: aggregate modification: respectively soaking the regenerated coarse aggregate and the regenerated fine aggregate in the epoxy emulsion, controlling the temperature to be 3-5 ℃, stirring and mixing for 10-15min, and then sieving to respectively obtain modified regenerated coarse aggregate and modified regenerated fine aggregate;
s2: modification of calcium aluminate: soaking calcium aluminate in polyetheramine, mixing and stirring for 25-30min, filtering, centrifuging and throwing off excessive polyetheramine on the surface to obtain modified calcium aluminate;
s3: uniformly mixing the modified recycled coarse aggregate and the modified recycled fine aggregate newly prepared in the step S1, adding the modified calcium aluminate newly prepared in the step S2 at the stirring speed of 150-200r/min for 6-8 times, wherein the adding interval is 5-8min each time, after the modified calcium aluminate is completely added, adding diatomite, and continuously mixing the mixture at the temperature of 45-50 ℃ at the stirring speed of 80-100r/min for 1.5-2h to obtain an aggregate mixture;
s4: and uniformly mixing the aggregate mixture, the cement, the water and the additive to obtain the recycled aggregate concrete.
2. The recycled aggregate concrete according to claim 1, wherein: the epoxy value of the epoxy emulsion used for modifying the recycled coarse aggregate and the recycled fine aggregate is 0.4-0.45.
3. The recycled aggregate concrete according to claim 2, wherein: the particle size of the dispersed phase in the epoxy emulsion used for modifying the recycled coarse aggregate and the recycled fine aggregate is 3-5 mu m.
4. The recycled aggregate concrete according to claim 1, wherein: the amine number of the polyetheramine used for modifying the calcium aluminate is 450-500.
5. The recycled aggregate concrete according to claim 1, wherein: the particle size of the recycled coarse aggregate is 25-35mm, and the particle size of the recycled fine aggregate is 2.5-2.8 mm.
6. The preparation process of recycled aggregate concrete according to claim 1, characterized in that: in step S2, the calcium aluminate is treated by ultrasonic treatment in the process of soaking by using polyether amine, and the frequency of the ultrasonic wave is controlled to be 20-23kHz in the ultrasonic process.
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