CN115872696A - High-strength concrete and preparation method thereof - Google Patents
High-strength concrete and preparation method thereof Download PDFInfo
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- CN115872696A CN115872696A CN202211308711.6A CN202211308711A CN115872696A CN 115872696 A CN115872696 A CN 115872696A CN 202211308711 A CN202211308711 A CN 202211308711A CN 115872696 A CN115872696 A CN 115872696A
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- 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
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- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Abstract
The application relates to high-strength concrete and a preparation method thereof, wherein the concrete is prepared from a concrete mixture, and the concrete mixture comprises the following components in parts by weight: 340-350 parts of cement, 80-100 parts of mineral powder, 800-850 parts of modified recycled coarse aggregate, 200-250 parts of modified recycled fine aggregate, 480-520 parts of medium sand, 140-150 parts of water, 60-80 parts of fly ash and 8-12 parts of polycarboxylic acid water reducer; the preparation of the modified recycled aggregate comprises three processing technologies of recycled aggregate acidification pretreatment, strengthening liquid impregnation strengthening and surface treatment of surface treatment liquid. The concrete has the advantages of improving the performance of the recycled aggregate and improving the strength of the concrete using the recycled aggregate.
Description
Technical Field
The application relates to the field of concrete, in particular to high-strength concrete and a preparation method thereof.
Background
In recent years, the shortage of gravels and the rising of sand price, the national increase of the policy of recycling construction wastes and environmental protection and saving construction, and researches show that 243 million standard bricks and 3600 million tons of mixed materials can be produced by using 1 million tons of construction wastes, soil taking is reduced or 1000 million cubic meters of natural gravels are replaced, 270 million tons of coal are saved, and the new yield value is increased by 84.6 million yuan; the construction waste recycling can also reduce the discharge of nitrous oxide by 50 percent and carbon monoxide by 28 percent of nitride by 99.3 percent, and reduce the waste of land resources and environmental pollution; in the field of concrete, the conversion rate of aggregate produced by construction waste can reach 85%, namely, 0.85 ton of recycled aggregate can be produced by 1 ton of construction waste, the cost is much lower than that of natural aggregate, and the recycled aggregate is increasingly applied to concrete preparation.
The recycled aggregate is put into use and needs to be crushed, cleaned and the like in advance, in the process of crushing the recycled concrete, micro cracks can appear on the recycled aggregate stones due to the collision effect under the crushing effect, inevitable damage occurs, the cracks of the recycled aggregate stones can influence the strength performance of the recycled aggregate stones and the combination between the recycled aggregate stones and cement paste and the strength performance of the recycled aggregate stones, and further the mechanical performance of the recycled concrete can be influenced.
In view of the above problems, the inventors of the present invention have considered that concrete produced using recycled aggregate has a drawback of low strength and high susceptibility to brittle fracture.
Disclosure of Invention
In order to improve the strength performance of concrete using recycled aggregate, the application provides high-strength concrete and a preparation method thereof.
In a first aspect, the present application provides a high strength concrete, which adopts the following technical scheme:
the high-strength concrete is prepared from a concrete mixture, wherein the concrete mixture comprises the following components in parts by weight:
340-350 parts of cement, 80-100 parts of mineral powder, 800-850 parts of modified regenerated coarse aggregate, 200-250 parts of modified regenerated fine aggregate, 480-520 parts of medium sand, 140-150 parts of water, 60-80 parts of fly ash and 8-12 parts of polycarboxylic acid water reducer;
the preparation method of the modified recycled aggregate comprises the following steps:
s1, recycled aggregate pretreatment:
s1-1, crushing and screening the recycled aggregate to respectively obtain recycled coarse aggregate with the particle size of 10-20mm and recycled fine aggregate with the fine particle size of 5-10 mm;
s1-1, putting the recycled coarse aggregate and the recycled fine aggregate into a phosphoric acid solution with the mass concentration of 5%, wherein the material-liquid ratio is 1;
s2, impregnation and strengthening:
s2-1, uniformly dispersing dandelion short fibers and kapok short fibers into a polyvinyl alcohol aqueous solution to obtain a strengthening solution; wherein the mass ratio of the dandelion short fibers, the kapok short fibers and the polyvinyl alcohol aqueous solution is (1-1.3): 0.5-0.7): 10; the mass percentage concentration of the polyvinyl alcohol aqueous solution is 1%; the fiber lengths of the dandelion short fibers and the kapok short fibers are not more than 5mm;
s2-1, soaking the recycled coarse aggregate and the recycled fine aggregate in a strengthening solution together, wherein the ratio of the materials to the liquids is 1:20, pressing the strengthening liquid into gaps of the recycled aggregate by a vacuum pressure method, filtering, cleaning and drying the aggregate to obtain the strengthened recycled aggregate;
s3, surface treatment;
s3-1, uniformly mixing coconut shell powder, nano talcum powder, swelling adhesive and water to obtain surface treatment liquid; wherein the mass ratio of the coconut shell powder, the nano talcum powder, the swelling adhesive and the water is 1.5, (6-8) to 10;
s3-2, soaking the reinforced recycled coarse aggregate and the recycled fine aggregate in the surface treatment liquid together, wherein the material-liquid ratio is 1: and 20, uniformly mixing, filtering and drying to obtain the modified recycled aggregate.
By adopting the technical scheme, the recycled aggregate obtained by crushing and screening is firstly acidified, and a phosphoric acid solution with the mass concentration of 5% can remove cement hydration products on the aggregate particles by reaction, so that the effect of removing impurities on the surface of the recycled aggregate particles is achieved; the regenerated aggregate activated by the acid solution is immersed into the strengthening liquid again, the strengthening liquid is extruded into cracks of the regenerated aggregate in a vacuum pressurization mode, dandelion short fibers and kapok short fibers in the strengthening liquid are filled into the cracks, and the cracks can be fully filled up through bonding and matching with the polyvinyl alcohol aqueous solution, so that a three-dimensional disorientation supporting net is formed in the concrete and bears the tensile stress generated by the plastic deformation of the concrete, the growth and development of the cracks of the regenerated aggregate are prevented, the generation of communicated cracks is greatly reduced, and the crack resistance of the regenerated aggregate is obviously improved; the toughness of the impregnated and reinforced recycled aggregate is increased, and when the recycled aggregate is impacted by external force, the fibers in the recycled aggregate have a certain load transfer effect, so that the recycled aggregate has better external force impact resistance, and the compressive strength of concrete is further improved; and finally, performing surface treatment on the reinforced recycled aggregate, and coating a surface treatment liquid obtained by compounding coconut shell powder, nano talcum powder, swelling adhesive and water on the surface of the aggregate, wherein the surface treatment liquid can seal the crack opening of the recycled aggregate, so that the improvement of the blocking tolerance of the surface of the recycled aggregate to acid, alkali, moisture and the like is facilitated, the surface treatment liquid can generate a swelling effect in the preparation process of concrete, the surface treatment liquid is filled in the concrete gap, the integral compactness of the concrete is improved, the surface treatment liquid can further improve the adhesive property between the recycled aggregate and the adhesive material and filler in the concrete, and further the strength, toughness and crack resistance of the concrete are improved.
This application is through carrying out the modification to the regeneration aggregate and reinforceing for the intensity, anti-crack, the corrosion resisting property of regeneration aggregate have all obtained promoting, and cooperate each other between regeneration coarse aggregate and the regeneration fine aggregate that the particle diameter is different with powdered ore, middlings, help improving the void structure of concrete, promote the holistic closely knit nature of concrete, make the concrete that makes have better intensity and crack resistance and impervious performance.
Preferably, in the step S2-1, the mass ratio of the dandelion short fibers, the kapok short fibers and the polyvinyl alcohol aqueous solution is 1.
By adopting the technical scheme, the composition proportion of the components in the strengthening liquid is further limited, so that each component can be in a proper range, and a better matching effect is realized; the dandelion fibers in the strengthening liquid have long thorns, have structural characteristics similar to feather fibers, have fluffy performance and can serve as a good filler without increasing the self weight of a basic structure of the recycled aggregate; the hollowness of kapok fiber is up to 80% -90%, better suspension has, the kapok surface has more wax to make the fibre smooth, do not absorb water, be difficult for tangling, better filling performance has equally, the two mutually supports, can make up for each other the weak point, and all select length for use in this application to be not more than 5 mm's short-staple, make the component in the reinforceing liquid can be more abundant the crack of filling regeneration aggregate, form the three-dimensional network structure that more closely knit firm in the crack, promote the closely knit nature and the toughness of regeneration aggregate, prevent further fracture of regeneration aggregate.
Preferably, fatty alcohol-polyoxyethylene ether is further added in the step S2-1, and the mass ratio of the fatty alcohol-polyoxyethylene ether, the dandelion short fibers, the kapok short fibers and the polyvinyl alcohol aqueous solution is 0.1.
By adopting the technical scheme, the addition of the fatty alcohol-polyoxyethylene ether is beneficial to the reinforcing liquid to better permeate into cracks of the recycled aggregate, so that the filling compactness of the components in the reinforcing liquid to the recycled aggregate is improved, and the reinforcing effect of the recycled aggregate is more obvious.
Preferably, the length of the dandelion short fiber is 1-5mm, and the length of the kapok short fiber is 3-5mm.
By adopting the technical scheme, the length of the fiber is limited, the fine and short fiber can be well dispersed in the polyvinyl alcohol aqueous solution, the short fiber is not easy to tangle and agglomerate, the fiber can be better filled into the cracks of the recycled aggregate along with the polyvinyl alcohol aqueous solution, and the short fiber can bridge the micro cracks distributed on the recycled aggregate and inhibit the micro cracks from developing into macro cracks, so that the strength and the toughness of the concrete are improved, and the cracks are reduced.
Preferably, the vacuum pressure method in the step S2-2 is to soak the recycled coarse aggregate and the recycled fine aggregate in the strengthening solution, put the obtained mixture into a vacuum drying oven, continuously vacuum the obtained mixture for 1 hour at normal temperature under the condition that the relative vacuum pressure is-75 KPa, then release the pressure to normal pressure, and vacuumize the obtained product for 30 minutes under the condition that the relative vacuum pressure is-55 KPa.
By adopting the technical scheme, vacuum pressurization is carried out under limited pressure and time, so that the strengthening liquid can be assisted to enter the cracks of the recycled aggregate, and the filling and strengthening of the recycled aggregate are realized; the vacuum pressurization mode of twice gradual pressure reduction is adopted, so that the stability of the strengthening liquid is enhanced, and the strengthening effect of the strengthening liquid on the recycled aggregate is further improved.
Preferably, the swelling adhesive in S3-1 is prepared by compounding xanthan gum, a polyvinyl alcohol aqueous solution, chitosan hydrogel and/or polyacrylamide hydrogel.
By adopting the technical scheme, the swelling adhesive contains hydrogel, and the hydrogel generates a swelling reaction in the preparation process of concrete, so that gaps in the concrete can be filled, and the overall compactness of the concrete is improved; the polyvinyl alcohol aqueous solution can play a good compatible role with the polyvinyl alcohol aqueous solution in the reinforcing liquid, so that the bonding communication between the surface layer and the inner layer of the recycled aggregate is realized, the bonding stability between the recycled aggregate and a cement sizing material is further improved, and the concrete performance is better; the swelling adhesive prepared by compounding the components has good stability and good water retention performance, and can improve the surface treatment effect of the surface treatment liquid on reinforced recycled aggregate, so that the recycled aggregate is bonded stably in concrete.
Preferably, the swelling adhesive in S3-1 is prepared by compounding xanthan gum, a polyvinyl alcohol aqueous solution and chitosan hydrogel according to a mass ratio of 1.
By adopting the technical scheme, the chitosan has good biocompatibility, safety and biodegradability, and a better synergistic cooperation effect can be generated among the chitosan hydrogel, the polyvinyl alcohol aqueous solution and the xanthan gum in the application, so that the coconut shell powder and the nano talcum powder can be better mixed and compatible in a surface treatment liquid system, and the surface treatment effect of the surface treatment liquid on the recycled aggregate is further improved.
In a second aspect, the preparation method of the high-strength concrete provided by the application adopts the following technical scheme:
a preparation method of high-strength concrete comprises the following steps:
step one, mixing the medium sand, the modified recycled coarse aggregate and water accounting for 70% of the total mass of the water, and uniformly stirring to obtain a coarse mixture;
step two, mixing cement, mineral powder, fly ash, modified recycled fine aggregate, polycarboxylic acid water reducer and the rest water, and uniformly stirring to obtain cement slurry;
adding the cement slurry into the coarse mixture, and uniformly stirring to obtain a concrete mixture;
and step four, curing the concrete mixture to obtain the high-strength concrete.
By adopting the technical scheme, the large-particle-size aggregate is prepared into the coarse mixing material, the small-particle-size fine aggregate, the filler and the cement are mixed to prepare the cement slurry, the cement slurry can be better mixed with the coarse mixing material, the system stability of the prepared concrete and the structural performance of the concrete are further improved, the prepared concrete has stronger strength and toughness, and the cracking is reduced.
In summary, the present application includes at least one of the following beneficial technical effects:
1. the method has the advantages that the modified recycled aggregate is used, the recycled aggregate obtained by crushing and screening is firstly acidified, and impurities on the surface of recycled aggregate particles are removed; the recycled aggregate activated by the acid solution is immersed in the strengthening liquid again, the strengthening liquid is extruded into cracks of the recycled aggregate in a vacuum pressurization mode, dandelion short fibers and kapok short fibers in the strengthening liquid are filled into the cracks, and the cracks can be fully plugged through bonding and matching with the polyvinyl alcohol aqueous solution, so that the growth and development of the cracks of the recycled aggregate are prevented, the toughness of the impregnated and strengthened recycled aggregate is increased, and the recycled aggregate has better external force impact resistance and crack resistance; finally, performing surface treatment on the reinforced recycled aggregate, wherein the surface treatment liquid can help the recycled aggregate to be uniformly dispersed in the concrete, seal the crack opening of the recycled aggregate, and improve the adhesive property among the recycled aggregate, the cement glue and the filler, so that the strength, the toughness and the crack resistance of the concrete are improved;
2. according to the application, the modified recycled coarse aggregate and the modified recycled fine aggregate with different particle sizes are selected and used, the modified recycled coarse aggregate and the modified recycled fine aggregate can replace a part of natural gravels, the resource recycling of building waste materials is realized, the modified recycled coarse aggregate and the modified recycled fine aggregate are matched with mineral powder and medium sand, the improvement of the void structure of concrete is facilitated, the overall compactness of concrete is improved, and the prepared concrete has better strength, crack resistance and impermeability.
Detailed Description
The present application will be described in further detail with reference to examples and comparative examples.
Preparation example
Preparation example 1
Preparation example 1 discloses a preparation method of a modified recycled aggregate, which specifically comprises the following steps:
s1, recycled aggregate pretreatment:
s1-1, crushing and screening the recycled aggregate to respectively obtain recycled coarse aggregate with the particle size of 10-20mm and recycled fine aggregate with the fine particle size of 5-10 mm;
s1-1, putting the regenerated coarse aggregate and the regenerated fine aggregate into a phosphoric acid solution with the mass concentration of 5% for soaking, wherein the material-liquid ratio is 1;
s2, impregnation and strengthening:
s2-1, dispersing dandelion short fibers with the length of 1-5mm and kapok short fibers with the length of 3-5mm into a polyvinyl alcohol aqueous solution, and stirring at a stirring speed of 30r/min for 5min to obtain a strengthening solution; wherein the mass ratio of the dandelion short fibers, the kapok short fibers and the polyvinyl alcohol aqueous solution is 1.5;
s2-1, soaking the recycled coarse aggregate and the recycled fine aggregate in a strengthening solution together, wherein the material-liquid ratio is 1:20, stirring for 15min at a stirring speed of 15r/min, then placing the mixture into a vacuum box, continuously vacuumizing for 1h at normal temperature under the condition that the vacuum relative pressure is-75 KPa, then decompressing to normal pressure, vacuumizing again, continuously maintaining for 30min under the condition that the vacuum relative pressure is-55 KPa, filtering out aggregate, washing 1 aggregate with water, and drying the washed aggregate at constant temperature of 60 ℃ for 6h to obtain the reinforced recycled aggregate;
s3, surface treatment;
s3-1, adding coconut shell powder, nano talcum powder, swelling adhesive and water into a stirring tank, and stirring for 20min at a stirring speed of 100r/min to obtain a surface treatment liquid; wherein the mass ratio of the coconut shell powder to the nano talcum powder to the mixed hydrogel to the water is 1.5; the swelling adhesive is prepared by mixing xanthan gum, a polyvinyl alcohol aqueous solution and chitosan hydrogel according to a mass ratio of 1;
and S3-2, soaking the reinforced recycled coarse aggregate and the reinforced recycled fine aggregate into the surface treatment liquid together, wherein the material-liquid ratio is 1.
Preparation example 2
The preparation example discloses a preparation method of modified recycled aggregate, which is different from the preparation example 1 in that: in the step S2-1, the mass ratio of the dandelion short fibers, the kapok short fibers and the polyvinyl alcohol aqueous solution in the strengthening solution is 1.3; in the step S3-1, the mass ratio of coconut shell powder, nano talcum powder, swelling adhesive and water in the surface treatment liquid is 1.5; the swelling adhesive is prepared by mixing xanthan gum, a polyvinyl alcohol aqueous solution and polyacrylamide hydrogel according to a mass ratio of 1.
Preparation example 3
The preparation example discloses a preparation method of modified recycled aggregate, which is different from the preparation example 1 in that: in the step S2-1, the mass ratio of the dandelion short fibers, the kapok short fibers and the polyvinyl alcohol aqueous solution in the strengthening solution is 1.2; in the step S3-1, the mass ratio of the coconut shell powder, the nano talcum powder, the swelling adhesive and the water in the surface treatment liquid is 1.5; the swelling adhesive is prepared by mixing xanthan gum, a polyvinyl alcohol aqueous solution, polyacrylamide hydrogel and chitosan hydrogel according to a mass ratio of 1.
Preparation example 4
The preparation example discloses a preparation method of modified recycled aggregate, which is different from the preparation example 3 in that: in the step S3-1, the swelling adhesive is prepared by mixing xanthan gum, a polyvinyl alcohol aqueous solution and chitosan hydrogel according to a mass ratio of 1.
Preparation example 5
The preparation example discloses a preparation method of modified recycled aggregate, which is different from the preparation example 3 in that: in the step S3-1, the swelling adhesive is prepared by mixing xanthan gum, a polyvinyl alcohol aqueous solution and chitosan hydrogel according to a mass ratio of 1.4.
Preparation example 6
The preparation example discloses a preparation method of modified recycled aggregate, which is different from the preparation example 3 in that: and step S2-1, adding fatty alcohol-polyoxyethylene ether, wherein the mass ratio of the fatty alcohol-polyoxyethylene ether, the dandelion short fibers, the kapok short fibers and the polyvinyl alcohol aqueous solution is 0.1.
Preparation example 7
The preparation example discloses a preparation method of modified recycled aggregate, which is different from the preparation example 6 in that: in the step S3-1, the swelling adhesive is prepared by mixing xanthan gum, a polyvinyl alcohol aqueous solution and chitosan hydrogel according to a mass ratio of 1.4.
Preparation example 8
The preparation example discloses a preparation method of modified recycled aggregate, which is different from the preparation example 3 in that: in the step S2-1, dandelion fibers with the length of 10-15mm are selected; kapok fiber with the length of 8-15mm is selected.
Preparation example 9
The preparation example discloses a preparation method of modified recycled aggregate, which is different from the preparation example 3 in that: in step S2-1, the dandelion fibers are replaced by cellulose staple fibers with the same amount.
Preparation example 10
The preparation example discloses a preparation method of modified recycled aggregate, which is different from the preparation example 3 in that: in step S3-1, the coconut shell powder and the nano talcum powder are replaced by the same amount of water.
Preparation example 11
The preparation example discloses a preparation method of modified recycled aggregate, which is different from the preparation example 3 in that: in the step S3-1, the swelling adhesive is replaced by the same amount of white dextrin.
Preparation example 12
The preparation example discloses a preparation method of modified recycled aggregate, which is different from the preparation example 3 in that: the recycled aggregate is not impregnated and strengthened.
Preparation example 13
The preparation example discloses a preparation method of modified recycled aggregate, which is different from the preparation example 3 in that: the recycled aggregate is not subjected to surface treatment.
Preparation example 14
The preparation example discloses a preparation method of recycled aggregate, which is different from the preparation example 3 in that: the recycled aggregate was not subjected to impregnation strengthening and surface treatment.
Examples
Examples 1 to 5
Embodiments 1-5 disclose a high strength concrete prepared from a concrete mix, comprising the following components in parts by mass: 340-350 parts of cement, 80-100 parts of mineral powder, 800-850 parts of modified regenerated coarse aggregate, 200-250 parts of modified regenerated fine aggregate, 480-520 parts of medium sand, 140-150 parts of water, 60-80 parts of fly ash and 8-12 parts of polycarboxylic acid water reducer;
examples 1-5 also disclose a method for preparing the above high strength concrete, comprising the steps of:
step one, mixing the medium sand, the modified recycled coarse aggregate and water accounting for 70% of the total mass of the water, and stirring for 10min at normal temperature and at the rotating speed of 50r/min to obtain a coarse mixture;
mixing P & O42.5 grade cement, S95 mineral powder, fly ash, modified recycled fine aggregate, polycarboxylic acid water reducer and the rest water, pouring the mixture into a stirrer, and stirring for 5min at normal temperature and the rotating speed of 70r/min to obtain cement slurry;
adding the cement slurry into the coarse mixture, and stirring for 10min at normal temperature and at the rotating speed of 70r/min to obtain a concrete mixture;
and step four, placing the concrete mixture into a standard curing room for curing for 28 days to obtain the high-strength concrete.
The amounts (unit: kg) of the respective raw material components of examples 1 to 5 are specified in Table 1.
TABLE 1
Examples 6 to 9
The preparation method of the high-strength concrete is different from the embodiment 5 in that the modified recycled aggregate prepared in the preparation examples 4-7 is selected correspondingly, and the specific selection is detailed in table 2.
TABLE 2
Comparative example
Comparative examples 1 to 7
The preparation method of the high-strength concrete is different from the embodiment 5 in that: the modified recycled aggregate prepared in preparation examples 8-14 is selected correspondingly.
Performance test
1. And (3) detecting the compressive strength: according to the method for testing the compressive strength in GB/T50081-2016 standard of test method for mechanical properties of common concrete, the concrete prepared in the embodiment and the comparative example is tested, the compressive strength directly reflects the compressive strength of the concrete, and the greater the compressive strength, the better the compressive strength of the concrete.
2. Splitting tensile strength test: according to the splitting tensile strength test method in GB/T50081-2016 standard of common concrete mechanical property test method, concrete mixtures prepared in examples and comparative examples are detected, the splitting tensile strength reflects the cracking resistance of concrete, and the larger the splitting tensile strength is, the stronger the internal cohesive force of the concrete is, and the better the cracking resistance is.
3. And (3) detecting the pressurized bleeding rate: according to a pressure bleeding test method in GB/T50080-2016 standard of Performance test methods for common concrete mixtures, concrete mixtures prepared in examples and comparative examples are detected, the pressure bleeding rate is an important index for reacting the water retention rate of concrete, and the smaller the pressure bleeding rate is, the less the water loss of concrete is, the better the water retention performance of concrete is, and the good water retention performance of concrete is beneficial to retarding concrete cracking.
The specific assay data for experiments 1-3 are detailed in Table 3.
TABLE 3
According to the performance test data of the concrete prepared in the examples 1 to 5 and the comparative examples 1 to 7 in table 3, the concrete prepared in the examples 1 to 5 of the present application using the modified recycled aggregate prepared in the preparation examples 1 to 3 has higher values of the compressive strength and the tensile strength at cleavage compared to the concrete prepared in the comparative examples, which indicates that the concrete prepared in the examples of the present application has better strength performance and crack resistance; the concrete prepared in the examples 1 to 5 has a smaller numerical value of the pressure bleeding rate than that of the concrete of the comparative example, which shows that the concrete prepared in the examples of the present application has better water retention.
In the embodiment 1-5, the modified recycled aggregate is used, the recycled aggregate is firstly acidified to remove impurities, and then is soaked in the reinforcing liquid, the dandelion short fibers and the kapok short fibers in the reinforcing liquid are filled into cracks, and the cracks can be fully filled through bonding and matching with the polyvinyl alcohol aqueous solution, so that a three-dimensional disorientation supporting net is formed in concrete, the growth and development of the recycled aggregate cracks can be prevented, the generation of communicated cracks is reduced, and the anti-cracking performance of the recycled aggregate is improved; the toughness of the impregnated and reinforced recycled aggregate is increased, and the aggregate has better external force impact resistance and compressive strength; the reinforced recycled aggregate is subjected to surface treatment, and coconut shell powder, nano talcum powder and swelling adhesive in the surface treatment liquid are cooperatively matched, so that crack openings of the recycled aggregate can be sealed, the barrier tolerance of the surface of the recycled aggregate to acid, alkali, moisture and the like is promoted, the adhesive property between the recycled aggregate and rubber and filler in concrete is promoted, and the strength, toughness and crack resistance of the concrete are further promoted.
In examples 6 to 8, the modified recycled aggregate prepared in preparation examples 4 to 7 is used, wherein the swelling adhesive in examples 6 and 7 is prepared by compounding xanthan gum, a polyvinyl alcohol aqueous solution, chitosan hydrogel and water according to a specific mass ratio, and the xanthan gum, the polyvinyl alcohol aqueous solution, the chitosan hydrogel and the water can generate a good synergistic effect, so that the coconut shell powder and the nano talc powder can be better compatible, and the surface treatment effect of the surface treatment liquid on the recycled aggregate can be improved.
In the embodiment 8, the fatty alcohol-polyoxyethylene ether is added into the strengthening liquid, and the addition of the fatty alcohol-polyoxyethylene ether is helpful for the strengthening liquid to fully permeate into cracks of the recycled aggregate, so that the strengthening effect is improved, and further the compressive strength performance of the concrete prepared in the embodiment 8 is obviously improved; in the embodiment 9, the component proportion of the swelling adhesive is limited, and the fatty alcohol-polyoxyethylene ether is added into the strengthening liquid, so that the concrete prepared in the embodiment 9 has the best performance.
Comparative example 1 the lengths of dandelion fiber and kapok fiber in the reinforcing liquid used for preparing concrete are beyond the range defined in the application, cellulose short fiber is adopted to replace dandelion fiber in comparative example 2, components in the reinforcing liquid are changed in comparative examples 1-2, the replaced substances are difficult to cooperate with each other, the filling effect on recycled aggregate is poor, and further, the performances of the concrete prepared in comparative examples 1-2 are reduced compared with the performances of the concrete prepared in example 5.
In the comparative example 3, coconut shell powder and nano talcum powder are replaced by equal amount of water, in the comparative example 4, swelling adhesive is replaced by equal amount of white dextrin, and the powdery filler in the surface treatment liquid is lost, so that the strength performance and the barrier property of the concrete are reduced, the white dextrin is difficult to be fully compatible with other components when being added into the surface treatment liquid, and a good water retention effect cannot be realized, and further the performance of the concrete prepared in the comparative examples 3 and 4 is influenced.
In comparative examples 5 to 7, the recycled aggregate is not subjected to complete modification treatment of impregnation strengthening and surface treatment in examples 1 to 5, and either treatment process of the two is absent, so that the performance improvement effect of the recycled aggregate after complete modification in examples 1 to 5 of the application is not achieved, the performance of the recycled aggregate directly influences the performance of the prepared concrete, and the performance of the concrete prepared in comparative examples 5 to 7 is poor.
The above embodiments are selected to embody the technical solution of the present application, and the protection scope of the present application is not limited thereby, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.
Claims (8)
1. A high-strength concrete is characterized in that: the concrete mixture is prepared from the following components in parts by weight:
340-350 parts of cement, 80-100 parts of mineral powder, 800-850 parts of modified regenerated coarse aggregate, 200-250 parts of modified regenerated fine aggregate, 480-520 parts of medium sand, 140-150 parts of water, 60-80 parts of fly ash and 8-12 parts of polycarboxylic acid water reducer;
the preparation method of the modified recycled aggregate comprises the following steps:
s1, recycled aggregate pretreatment:
s1-1, crushing and screening the recycled aggregate to respectively obtain recycled coarse aggregate with the particle size of 10-20mm and recycled fine aggregate with the fine particle size of 5-10 mm;
s1-1, putting the recycled coarse aggregate and the recycled fine aggregate into a phosphoric acid solution with the mass concentration of 5%, wherein the material-liquid ratio is 1:10, soaking for 24 hours, washing with water and drying;
s2, impregnation and strengthening:
s2-1, uniformly dispersing dandelion short fibers and kapok short fibers into a polyvinyl alcohol aqueous solution to obtain a strengthening solution; wherein the mass ratio of the dandelion short fibers, the kapok short fibers and the polyvinyl alcohol aqueous solution is (1-1.3): 0.5-0.7): 10, and the mass percentage concentration of the polyvinyl alcohol aqueous solution is 1%; the fiber lengths of the dandelion short fibers and the kapok short fibers are not more than 5mm;
s2-1, soaking the recycled coarse aggregate and the recycled fine aggregate in a strengthening solution together, wherein the material-liquid ratio is 1:20, pressing strengthening liquid into gaps of the recycled aggregate by a vacuum pressure method, filtering, cleaning and drying the aggregate to obtain the strengthened recycled aggregate;
s3, surface treatment;
s3-1, uniformly mixing coconut shell powder, nano talcum powder, swelling adhesive and water to obtain a surface treatment fluid; wherein the mass ratio of the coconut shell powder, the nano talcum powder, the swelling adhesive and the water is 1.5 (6-8) to 10;
s3-2, soaking the reinforced recycled coarse aggregate and the recycled fine aggregate in the surface treatment liquid together, wherein the ratio of the materials to the liquids is 1: and 20, uniformly mixing, filtering and drying to obtain the modified recycled aggregate.
2. The high-strength concrete according to claim 1, wherein: in the step S2-1, the mass ratio of the dandelion short fibers, the kapok short fibers and the polyvinyl alcohol aqueous solution is 1.
3. The high-strength concrete according to claim 2, wherein: and in the step S2-1, fatty alcohol-polyoxyethylene ether is added, wherein the mass ratio of the fatty alcohol-polyoxyethylene ether, the dandelion short fiber, the kapok short fiber and the polyvinyl alcohol aqueous solution is 0.1.
4. A high strength concrete according to any one of claims 1 to 3, wherein: the length of the dandelion short fiber is 1-5mm, and the length of the kapok short fiber is 3-5mm.
5. The high-strength concrete according to claim 1, wherein: and the vacuum pressure method in the step S2-2 is to soak the recycled coarse aggregate and the recycled fine aggregate in the strengthening solution, put the recycled coarse aggregate and the recycled fine aggregate in a vacuum drying box, continuously vacuum the recycled coarse aggregate and the recycled fine aggregate for 1 hour under the condition of vacuum relative pressure of-75 KPa at normal temperature, then release the pressure to normal pressure, and vacuumize the recycled coarse aggregate and the recycled fine aggregate for 30 minutes under the condition of vacuum relative pressure of-55 KPa.
6. The high-strength concrete according to claim 1, wherein: the swelling adhesive in S3-1 is prepared by compounding xanthan gum, a polyvinyl alcohol aqueous solution, chitosan hydrogel and/or polyacrylamide hydrogel.
7. The high-strength concrete according to claim 6, wherein: the swelling adhesive in the S3-1 is prepared by compounding xanthan gum, a polyvinyl alcohol aqueous solution and chitosan hydrogel according to a mass ratio of 1.
8. A method for preparing the high-strength concrete according to any one of claims 1 to 7, wherein: the method comprises the following steps:
step one, mixing the medium sand, the modified recycled coarse aggregate and water accounting for 70% of the total mass of the water, and uniformly stirring to obtain a coarse mixture;
step two, mixing cement, mineral powder, fly ash, modified recycled fine aggregate, polycarboxylic acid water reducer and the rest water, and uniformly stirring to obtain cement slurry;
adding the cement slurry into the coarse mixture, and uniformly stirring to obtain a concrete mixture;
and step four, curing the concrete mixture to obtain the high-strength concrete.
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| CN112830740A (en) * | 2021-01-22 | 2021-05-25 | 广州市粤砼混凝土有限公司 | Fair-faced concrete produced from construction waste recycled aggregate |
| CN114149222A (en) * | 2021-11-05 | 2022-03-08 | 深圳市坤鹏环保建筑废料处理有限公司 | Environment-friendly recycled brick and preparation process thereof |
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| KR101173442B1 (en) * | 2012-04-04 | 2012-08-16 | 국보환경(주) | Permeable concrete block manufacture method to use eco-friendly recycled aggregate coated |
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| CN111393110A (en) * | 2020-03-28 | 2020-07-10 | 德清高盛交通科技有限公司 | Full-machine-made sand masonry mortar with limestone as aggregate and preparation method thereof |
| CN112830740A (en) * | 2021-01-22 | 2021-05-25 | 广州市粤砼混凝土有限公司 | Fair-faced concrete produced from construction waste recycled aggregate |
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