CN115745472A - Concrete coarse aggregate - Google Patents
Concrete coarse aggregate Download PDFInfo
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- CN115745472A CN115745472A CN202211487398.7A CN202211487398A CN115745472A CN 115745472 A CN115745472 A CN 115745472A CN 202211487398 A CN202211487398 A CN 202211487398A CN 115745472 A CN115745472 A CN 115745472A
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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
- Y02W30/00—Technologies for solid waste management
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Abstract
The application relates to the technical field of building materials, and particularly discloses a concrete coarse aggregate. The concrete coarse aggregate is prepared from the following components in parts by weight: 80-90 parts of recycled coarse aggregate; 5-15 parts of cement extravasation Kim powder slurry; 1-5 parts of polycarboxylic acid high-performance water reducing agent; 0.5-1 part of nano silicon dioxide sol; 1-5 parts of modified organic silicon resin; 1-5 parts of a catalyst; the modified organic silicon resin comprises the following components in parts by weight: 0.5-2 parts of organic silicon resin; 0.1-0.5 part of active zinc oxide; 0.01-0.05 part of surface treating agent; 0.01-0.02 portion of isopropanol. The concrete coarse aggregate prepared by the method has the effects of low water absorption, high strength and good durability.
Description
Technical Field
The application relates to the technical field of building materials, in particular to a concrete coarse aggregate.
Background
The concrete coarse aggregate is sand and stone which play a role of a framework in concrete, and occupies the largest volume in the concrete. In the long hydration reaction process of the concrete, the volume of the coarse aggregate is not changed in the concrete, and the volume stability of the concrete is ensured to the maximum extent.
In order to reasonably utilize waste resources, it is proposed in the related art to recycle waste concrete generated by demolishing buildings and to use the recycled concrete to prepare recycled coarse aggregate for building structures. However, compared with natural concrete coarse aggregate, the surface of the prepared recycled coarse aggregate is adhered with a large amount of hardened cement sand, so that the surface of the recycled coarse aggregate is rough and has multiple edges and corners, the recycled coarse aggregate generates a large amount of fine cracks due to mechanical action in the crushing process, the water absorption rate is high, the mass loss rate is high, the prepared concrete has relatively poor durability, and the strength and the application tolerance are required to be improved.
Disclosure of Invention
In order to enable the coarse aggregate to meet the performance requirements of low water absorption, high strength, good durability and high application tolerance, the application provides the concrete coarse aggregate.
The application provides a concrete coarse aggregate adopts following technical scheme:
the concrete coarse aggregate is prepared from the following components in parts by weight:
80-90 parts of recycled coarse aggregate;
5-15 parts of cement extravasation Kim powder slurry;
0.5-1 part of polycarboxylic acid high-performance water reducing agent;
0.01-0.05 part of nano silicon dioxide sol;
1-5 parts of modified organic silicon resin;
0.01-0.05 part of catalyst;
wherein the modified organic silicon resin comprises the following components in parts by weight: 0.5-2 parts of organic silicon resin; 0.1-0.5 part of active zinc oxide; 0.01-0.05 part of surface treating agent; 0.01-0.02 portion of isopropanol.
By adopting the scheme, the nano silicon dioxide sol has good dispersibility and is basically dispersed in the solution in a single particle form, a silica structure can be formed, the solution has hydrophobicity, the nano silicon dioxide sol is added into the polycarboxylic acid high-performance water reducing agent, the obtained modified water reducing agent has high water reducing rate, good workability and wide applicability, the strength, toughness, waterproof performance and ageing resistance of the modified water reducing agent can be improved, and gaps in the soaked regenerated coarse aggregate can be repaired by matching the water reducing agent with the exosmosis Kim powder slurry, so that the particle type of the aggregate is smooth, the edges and corners are not prominent, the modified water reducing agent is easier to be uniformly distributed, the aggregate interface is more compact, and the compressive strength is improved.
The concrete is characterized in that cement slurry is coated on the outer layer of the regenerated coarse aggregate, and then a solution formed by mixing modified organic silicon resin and a catalyst is sprayed on the surface of the regenerated coarse aggregate, wherein the modified organic silicon resin has the characteristics of oxidation resistance, wear resistance, strong hydrophobicity and good permeability, holes and micro cracks which are not filled in the surface of the regenerated coarse aggregate can be blocked after curing and film forming, so that a film is covered on the surface of the aggregate, the surface is more uniform, the water absorption rate of the regenerated coarse aggregate is greatly reduced, and therefore the concrete coarse aggregate with low water absorption rate, higher strength and good durability can be obtained, and the prepared concrete can be suitable for more building structures.
Preferably, the preparation of the modified silicone resin comprises the following steps:
step one, mixing and stirring 1-5% of surface treating agent and acetone solution, adding isopropanol, stirring uniformly, adding active zinc oxide, stirring at a high speed for 1.5-2h to mix uniformly, and performing suction filtration and drying on the mixture to obtain modified zinc oxide;
and step two, adding the modified zinc oxide into the organic silicon resin, and mixing and stirring uniformly to obtain the modified organic silicon resin.
By adopting the scheme, the active zinc oxide has larger specific surface area, the active zinc oxide particles pretreated by the surface treating agent have more action points with the organic silicon resin, and can form stronger interface interaction by compounding with the organic silicon resin, and the active zinc oxide particles are more uniformly distributed on the organic silicon resin and have good compatibility, and the tensile property of the organic silicon resin can be improved, so that the film covered on the surface of the regenerated coarse aggregate treated by the modified organic silicon resin is more uniformly distributed, the aggregate can be better permeated and wrapped, and the aggregate is strengthened.
Preferably, the surface treatment agent is one of a silane coupling agent KH540, a silane coupling agent KH550 and a silane coupling agent KH-560.
By adopting the scheme, the amino and the ethoxy in the silane coupling agent KH540 are respectively used for coupling the organic polymer and the inorganic filler, so that the cohesiveness of the organic polymer and the inorganic filler can be enhanced, the performances of water resistance, ageing resistance and the like and physical and mechanical properties of the product can be improved, and the wettability and the dispersibility of the filler in the polymer can be improved; the silane coupling agent KH550 can optimize the compatibility between high molecules and inorganic matters in the composite material, and obviously improve the physical and mechanical properties such as tensile property, bending resistance and the like and the water resistance and the like of the composite material; the silane coupling agent KH-560 is used as a surface treatment agent to improve the adhesion between the resin and the base material and inorganic filler.
Preferably, the recycled coarse aggregate: cement extravasation Kim powder slurry: the mass ratio of the modified organic silicon resin is (4-4.5): (0.4-0.5): (0.05-0.1).
By adopting the scheme, the mass ratio of the recycled coarse aggregate, the cement extravasation Kim powder slurry and the modified organic silicon resin is limited, so that the performance of the recycled coarse aggregate under the double actions of the filled slurry and the film coated on the outermost layer can be better improved, the interface compactness of the aggregate is increased, and the water absorption rate can be greatly reduced.
Preferably, the Kim powder doping amount in the cement extravasation Kim powder slurry is 5-10%, and the water-gel ratio is 0.6-1.0.
By adopting the scheme, the Kim powder can chemically react with cement to generate insoluble needle-shaped crystals which are filled in gaps of the regenerated coarse aggregate, so that water can be prevented from entering the regenerated coarse aggregate, the durability and the service life of the regenerated coarse aggregate are enhanced, the doping amount and the water-cement ratio of the Kim powder are limited, and the treatment effect of cement exosmosis Kim powder slurry on the regenerated coarse aggregate is better.
Preferably, the recycled coarse aggregate is prepared by the following steps:
step one, grinding the waste concrete material to obtain a plurality of fragments;
step two, screening the fragments obtained in the step one, and screening the fragments with the particle size of 10-20mm by a screening machine to obtain regenerated coarse aggregate briquettes;
and step three, washing the recycled coarse aggregate compact obtained in the step two with water, and drying for later use.
By adopting the scheme, the fragments with proper particle sizes are selected through rolling and screening work and are cleaned for standby, so that the obtained regenerated coarse aggregate can be better subjected to subsequent modification operation, and the concrete coarse aggregate with wider applicability is obtained.
Preferably, the nano-silica sol is one of acrylate modified nano-silica sol, methyl modified nano-silica sol and epoxy modified nano-silica sol.
By adopting the scheme, the methyl modified nano-silica sol is alkyl functionalized nano-silica sol, and the methyl is connected in a chemical bond form, so that the dispersibility and the cohesiveness of the nano-silica in the water reducing agent are improved; the methacrylate functionalized nano-silica sol can enhance the crack growth resistance and the water resistance after being mixed with the water reducing agent; epoxy group in the epoxy group modified nano silicon dioxide sol has strong reactivity, and can accelerate the mixing action of the nano silicon dioxide and the water reducing agent.
Preferably, the catalyst is one of n-butyl titanate, tetraisopropyl titanate and ethyl titanate.
By adopting the scheme, the n-butyl titanate, the tetraisopropyl titanate and the ethyl titanate have higher activity, which is beneficial to enhancing the adhesion of the modified organic silicon resin on the surface of the aggregate, so that the modified organic silicon resin is better adhered to the surface of the regenerated coarse aggregate.
The application also provides a preparation method of the concrete coarse aggregate, which adopts the following technical scheme:
a preparation method of concrete coarse aggregate comprises the following steps:
s1, dropwise adding nano silica sol with solid content of 50% into a polycarboxylic acid high-performance water reducing agent, wherein the adding amount is 2-5%, stirring is kept in the adding process to obtain a mixed water reducing agent, and then mixing the mixed water reducing agent with cement extravasation Kim powder slurry by the weight ratio of (0.1-0.2): 1, mixing and stirring to obtain modified cement slurry;
and S2, soaking the regenerated coarse aggregate into the modified cement slurry for 3-5 hours, stirring once every 0.5 hour during soaking, taking out the regenerated coarse aggregate, draining excessive cement silica fume slurry, and maintaining for 4 weeks in a standard curing room.
And S3, adding 1-2% of catalyst by mass into the modified organic silicon resin, uniformly stirring, adding water to dilute until the concentration of the solution is 2-4%, spraying the solution onto the surface of the cured regenerated coarse aggregate, and finally drying in a 180 ℃ oven to obtain the concrete coarse aggregate.
By adopting the scheme, the modified cement slurry is prepared firstly to soak the regenerated coarse aggregate, so that the internal gap of the regenerated coarse aggregate is filled, the edges and corners of the surface of the regenerated coarse aggregate are repaired to be flat, then the modified organic silicon resin is sprayed on the surface of the regenerated coarse aggregate to form a surface coating film, so that the surface of the regenerated coarse aggregate is repaired more thoroughly, the water absorption rate of the regenerated coarse aggregate is greatly reduced, and the concrete coarse aggregate with low water absorption rate and good durability is obtained by limiting specific operation steps.
In summary, the present application has the following beneficial effects:
1. according to the application, the regenerated coarse aggregate is subjected to modified cement slurry soaking and modified organic silicon resin coating dual modification, and the nano silicon dioxide sol is added into the polycarboxylic acid high-performance water reducing agent, so that the strength, toughness, waterproof performance and ageing resistance of the regenerated coarse aggregate are improved, gaps in the soaked regenerated coarse aggregate can be repaired by matching the water reducing agent with the exosmosis Kim powder slurry, an aggregate interface is more compact, and the water absorption rate is greatly reduced, so that the concrete prepared from the concrete coarse aggregate has higher strength, and the application range of the concrete can be widened;
2. according to the method, the surface-treated active zinc oxide particles are filled in the organic silicon resin, so that the tensile property of the organic silicon resin is improved, a film covered on the surface of the regenerated coarse aggregate treated by the modified organic silicon resin is distributed more uniformly, the aggregate can be better permeated and coated, and the aggregate is strengthened;
3. the concrete preparation method for modifying the recycled coarse aggregate is limited in the application, the recycled coarse aggregate is soaked in the modified cement slurry, and then the modified organic silicon resin is sprayed to form a coating film, so that the concrete coarse aggregate with low water absorption and good durability is obtained.
Detailed Description
The present application will be described in further detail below with reference to preparation examples, examples and comparative examples.
Preparation examples
Preparation example 1: preparation of modified silicone resins
Step one, mixing 0.05g of silane coupling agent KH550 into an acetone solution, stirring for 10min, adding 40mL of isopropanol, uniformly stirring, adding 0.3g of active zinc oxide, stirring at a high speed for 1.5h, and carrying out suction filtration and drying on a mixture to obtain modified zinc oxide;
and step two, adding the modified zinc oxide into 0.65g of organic silicon resin, and stirring and mixing uniformly at a high speed to obtain the modified organic silicon resin.
Preparation example 2:
the present production example differs from production example 1 in that 0.25g of silane coupling agent KH550, 1.5g of active zinc oxide, and 3.25g of silicone resin were used.
Preparation example 3:
the difference between this preparation example and preparation example 1 is that 0.1g of silane coupling agent KH550, 0.6g of active zinc oxide, and 1.3g of silicone resin were used.
Preparation example 4:
the difference between the preparation example and the preparation example 1 is that 0.075g of silane coupling agent KH550, 0.45g of active zinc oxide and 0.975g of silicone resin are used.
Preparation example 5:
the difference between the preparation example and the preparation example 1 is that 0.04g of silane coupling agent KH550, 0.24g of active zinc oxide and 0.52g of silicone resin are used.
Preparation example 6:
the difference between this preparation example and preparation example 1 is that 0.4g of silane coupling agent KH550, 2.4g of active zinc oxide, and 5.2g of silicone resin were used.
Examples
Example 1:
the concrete coarse aggregate consists of the following components: 80g of recycled coarse aggregate, 5g of cement extravasation Kim powder slurry, 0.8g of polycarboxylic acid high-performance water reducing agent, 0.05g of acrylate modified nano silica sol, 1g of modified organic silicon resin and 0.02g of n-butyl titanate. The pretreatment of the recycled coarse aggregate comprises the following steps:
step one, grinding the waste concrete material to obtain a plurality of fragments;
screening the fragments obtained in the step one, and screening the fragments with the particle size of 10-20mm by a screening machine to obtain regenerated coarse aggregate briquettes;
and step three, washing the regenerated coarse aggregate briquettes obtained in the step two with water, and drying for later use.
The preparation method of the concrete coarse aggregate comprises the following steps:
s1, dropwise adding nano silica sol with the solid content of 50% into a polycarboxylic acid high-performance water reducing agent, wherein the adding amount is 5%, stirring is kept in the adding process to obtain a mixed water reducing agent, and then mixing the mixed water reducing agent with cement extravasation Kim powder slurry in a ratio of 0.1:1, and mixing and stirring, wherein the Kim powder doping amount in the Kim powder slurry seeped outside the cement is 5%, and the water-cement ratio is 0.6 to obtain modified cement slurry;
and S2, soaking the pretreated recycled coarse aggregate in the modified cement slurry for 5 hours, stirring every 0.5 hour during soaking, taking out the recycled coarse aggregate, draining excessive cement silica fume slurry, and curing in a standard curing room with the temperature of 20 ℃ and the relative humidity standard of 97% for 4 weeks.
S3, carrying out secondary modification by adopting the modified organic silicon resin obtained in the preparation example 1: adding tetrabutyl titanate into the modified organic silicon resin, stirring uniformly, adding water to dilute until the concentration of the solution is 3%, spraying the solution on the surface of the cured regenerated coarse aggregate, and finally drying in a drying oven at 180 ℃ to obtain a concrete coarse aggregate finished product.
Example 2:
a concrete coarse aggregate differing from example 1 in that it consists of the following components: 90g of recycled coarse aggregate, 15g of cement-extravasated Kim powder slurry, 0.8g of polycarboxylic acid-based high-performance water reducing agent, 0.05g of acrylate-modified nano-silica sol, 5g of modified silicone resin, and 0.1g of n-butyl titanate, and S3 in the preparation of this example employs the modified silicone resin obtained in preparation example 2.
Example 3:
a concrete coarse aggregate differing from example 1 in that: the mass of the cement extravasation Kim powder slurry in the components of the concrete coarse aggregate is 8g.
Example 4:
a concrete coarse aggregate differing from example 1 in that: 90g of recycled coarse aggregate, 10g of cement-extravasated Kim powder slurry, 0.8g of polycarboxylic acid-based high-performance water reducing agent, 0.05g of nano silica sol, 2g of modified silicone resin, 0.04g of n-butyl titanate, and S3 in the preparation of this example was the modified silicone resin obtained in preparation example 3.
Example 5:
a concrete coarse aggregate, which is different from the concrete coarse aggregate in example 1: 86g of recycled coarse aggregate, 9g of cement-extravasated Kim powder slurry, 0.8g of polycarboxylic acid-based high-performance water reducing agent, 0.05g of nano silica sol, 1.5g of modified silicone resin, and 0.03g of n-butyl titanate, and S3 in the preparation of this example was the modified silicone resin obtained in preparation example 4.
Example 6:
a concrete coarse aggregate differing from example 5 in that: the Kim powder doping amount of the used cement extravasation Kim powder slurry is 10%.
Example 7:
a concrete coarse aggregate differing from example 5 in that: the Kim powder doping amount of the used cement extravasation Kim powder slurry is 8%.
Example 8:
a concrete coarse aggregate, which is different from the concrete coarse aggregate in example 1: the nano-silica sol used in the components of the concrete coarse aggregate is methyl modified nano-silica sol.
Example 9:
a concrete coarse aggregate differing from example 5 in that: the nano silica sol used in the concrete coarse aggregate is epoxy modified nano silica sol.
Example 10:
a concrete coarse aggregate, which is different from example 5 in that: the catalyst used in combination with the modified organic silicon resin in the components of the concrete coarse aggregate is tetraisopropyl titanate.
Example 11:
a concrete coarse aggregate, which is different from example 5 in that: the catalyst used in combination with the modified organic silicon resin in the components of the concrete coarse aggregate is ethyl titanate.
Example 12:
a concrete coarse aggregate, which is different from example 5 in that: the composition consists of the following components: 86g of recycled coarse aggregate, 9g of cement-extravasated Kim powder slurry, 0.8g of polycarboxylic acid-based high-performance water reducing agent, 0.05g of epoxy-modified nano silica sol, 1.5g of modified organic silicon resin and 0.03g of n-butyl titanate, wherein in the preparation of the embodiment, the Kim powder doping amount in the cement-extravasated Kim powder slurry adopted in S1 is 8%, the water-to-gel ratio is 0.6, and the modified organic silicon resin obtained in the preparation example 4 is adopted in S3.
Comparative example
Comparative example 1:
a concrete coarse aggregate differing from example 1 in that: the composition consists of the following components: 70g of recycled coarse aggregate, 3g of cement extravasation Kim powder slurry, 0.8g of polycarboxylic acid type high-performance water reducing agent, 0.05g of acrylate modified nano silica sol, 0.8g of modified organic silicon resin and 0.016g of n-butyl titanate, wherein S3 in the preparation of the embodiment adopts the modified organic silicon resin obtained in the preparation example 5.
Comparative example 2:
a concrete coarse aggregate, which is different from the concrete coarse aggregate in example 1: the composition consists of the following components: 95g of recycled coarse aggregate, 20g of cement-extravasated Kim powder slurry, 0.8g of polycarboxylic acid-based high-performance water reducing agent, 0.05g of acrylate-modified nano-silica sol, 8g of modified silicone resin, and 0.16g of n-butyl titanate, and S3 in the preparation of this example employs the modified silicone resin obtained in preparation example 6.
Comparative example 3:
a concrete coarse aggregate, which is different from the concrete coarse aggregate in example 1: the Kim powder doping amount of the used cement extravasation Kim powder slurry is 4%.
Comparative example 4:
a concrete coarse aggregate, which is different from the concrete coarse aggregate in example 1: the Kim powder doping amount of the used cement extravasation Kim powder slurry is 12%.
Comparative example 5:
a concrete coarse aggregate differing from example 1 in that: the nano-silica sol used in the components of the concrete coarse aggregate is unmodified nano-silica sol.
Comparative example 6:
a concrete coarse aggregate, which is different from the concrete coarse aggregate in example 1: no catalyst is used in combination with the modified silicone resin.
Comparative example 7:
a concrete coarse aggregate, which is different from the concrete coarse aggregate in example 1: the unmodified organic silicon resin is matched with n-butyl titanate for use.
Performance test
Detection method
Experiment I, water absorption test: placing the aggregate into a tray, injecting clean water until the height of the aggregate is about 20mm higher than the aggregate, gently stirring the aggregate to completely discharge attached bubbles, soaking for 24 hours at room temperature of 23 ℃, hanging the hanging basket on a balance base hook and placing the hanging basket into an overflow water tank, injecting clean water into the water tank until the water surface reaches an overflow hole, adjusting the balance to zero, transferring the aggregate into the hanging basket, discharging part of water from the overflow hole, and keeping the water surface height unchanged. The mass in water of the aggregate is weighed and recorded as m 0 Lifting the hanging basket, taking out the aggregate, wiping the surface moisture of the aggregate one by using a wringed wet towel, and immediately weighing the surface dry mass of the aggregate as m 1 Placing the aggregate in a drying oven at 110 ℃ to dry until the mass of the aggregate is not changed, placing the aggregate in a carton, cooling the aggregate to room temperature, weighing the drying mass of the aggregate and recording the drying mass as m 2 And then calculating the water absorption of the aggregate by a formula.
Experiment two, apparent density measurement: soaking a proper amount of aggregate finished product in clean tap water for more than 24 hours, then putting the aggregate finished product into a wide-mouth bottle, adding clean water into the wide-mouth bottle until the aggregate finished product is close to a bottle opening, slightly shaking the bottle body to discharge bubbles in the wide-mouth bottle, slowly adding the clean water into the wide-mouth bottle until the bubbles slightly protrude out of the edge of the bottle opening after the bubbles are completely discharged, quickly sliding a glass sheet from the edge until the bottle opening is covered, wiping the bottle body dry by a towel, weighing the mass of the glass bottle, the glass sheet, the water and the aggregate and recording the mass as m 1 Taking out the aggregate from the bottle, drying the aggregate in a drying oven, cooling the aggregate to room temperature, and weighing the aggregate to record the mass as m 0 Cleaning a wide-mouth bottle, filling water into the wide-mouth bottle until the water surface slightly protrudes out of the edge of the bottle mouth, quickly sliding a glass sheet from the edge until the glass sheet covers the bottle mouth, wiping the bottle body with a towel, weighing the glass bottle, the glass sheet and the water, and recording the mass as m 2 And then the apparent density of the aggregate can be obtained by calculation through a formula.
Experiment three, crushing value determination: the recycled coarse aggregate was divided into 3 groups of 3000g each. The aggregate is uniformly added into a metal barrel of a crushing index tester for three times, the aggregate is vibrated to be compact after being added every time, and finally, the surface is carefully leveled by a metal scraper. Placing the barrel filled with the aggregate on a press, and pressing the pressure headPlacing on the surface of aggregate and keeping it flat. And opening the press to uniformly apply the load, and unloading after the maximum load reaches 400KN and the voltage is stabilized for 5s within 300 s. Taking out the barrel filled with the aggregate, pouring out the aggregate, weighing the aggregate and recording the mass as m 0 And screening the pressed aggregate by using a square-hole screen with the diameter of 2.36mm until no obvious screening material exists within 1 min. Weighing the mass m of the oversize aggregate l And (5) accurate to lg.
The result of the detection
The results of the performance test experiments on the finished aggregate products obtained in examples 1 to 12 and comparative examples 1 to 6 are shown in Table 1.
TABLE 1 Performance test data for examples 1-12 and comparative examples 1-6
As can be seen from the experimental data of Table 1, the water absorption of the coarse aggregates obtained in examples 1 to 12 is 2.25 to 3.12%, and the water absorption of the coarse aggregates obtained in comparative examples 1 to 7 is 3.12 to 4.12%, which indicates that the concrete coarse aggregates obtained by the preparation methods of examples 1 to 12 have lower water absorption, and can effectively prevent water from entering the aggregates, thereby reducing the water cost for preparing the recycled coarse aggregates in concrete; the apparent density of the coarse aggregates obtained in examples 1 to 12 was 2539 to 2620kg/m 3 The apparent density of the coarse aggregate obtained in comparative examples 1 to 7 was 2456 to 2510kg/m 3 The results show that the coarse aggregates obtained in examples 1-12 have better compactness and are beneficial to improving the strength of the prepared concrete; the crushing values of the coarse aggregates obtained in examples 1 to 12 were 14.3 to 16.2%, and the crushing values of the coarse aggregates obtained in comparative examples 1 to 7 were 16.3 to 17.2%, indicating that the coarse aggregates obtained in examples 1 to 12 were more excellent in compression resistance and applicable to more building structures.
Comparing example 1 with comparative examples 1-2, it can be seen that the mass ratio of the recycled coarse aggregate to the cement-infiltrated Kim powder slurry and the modified silicone resin is (4-4.5): (0.4-0.5): the modified coarse aggregate obtained in the range of (0.05-0.1) has lower water absorption and smaller crushing value, which shows that in the range of the mass ratio, the performance of the regenerated coarse aggregate can be better improved under the dual actions of the filled slurry and the film coated on the outermost layer, the interface compactness of the aggregate is increased, and the water absorption can also be greatly reduced; comparing example 1 with comparative examples 3-4, it can be seen that when the Kim powder is doped into the cement extravasation Kim powder slurry in a mass ratio of 5-10%, the apparent density of the obtained modified coarse aggregate is larger and the crushing value is smaller, which indicates that the Kim powder doping amount is limited, so that the Kim powder and the cement can better react to generate an appropriate amount of insoluble needle-shaped crystals, the needle-shaped crystals are filled into the gaps of the recycled coarse aggregate to enhance the durability and service life of the aggregate, and the treatment effect is better; comparing example 1 with comparative example 5, it can be seen that the modified coarse aggregate obtained in example 1 has lower water absorption and higher apparent density, which illustrates that the modified nano silica sol is mixed with the polycarboxylic acid-based high performance water reducing agent to obtain a modified water reducing agent which has better matching effect with the extravasated Kim powder slurry, and gaps inside the soaked recycled coarse aggregate can be better repaired, so that the aggregate has rounded grain shape, no protruding edges and corners, and is easier to distribute uniformly, the aggregate interface is more dense, and the compressive strength is improved; comparing example 1 with comparative example 6, it can be seen that when the coarse aggregate is sprayed without the catalyst and the modified silicone resin, the water absorption of the coarse aggregate obtained in comparative example 6 cannot be well reduced, the apparent density is small, the crushing value is large, and the aggregate performance is not good, which indicates that the formed surface film body cannot well prevent water from entering the coarse aggregate from micro-gaps without the promotion of the catalyst, and the extensibility is not good; it can be seen from comparison between example 1 and comparative example 7 that when the crude aggregate is secondarily modified by using the unmodified silicone resin, although the reduction range of the water absorption rate is large, the data measured by the crushing value and the apparent density are not good enough, which indicates that the coated film formed by the silicone resin modified by the active zinc oxide has better extensibility and strength and better coating effect, and can be better matched with the filling of the cement exosmosis Kim powder slurry to the recycled crude aggregate, and the synergistic effect is good.
Comparative example 1 with examples 2 to 5, recycled coarse aggregate is preferred: cement extravasation Kim powder slurry: the mass ratio of the modified organic silicon resin is 4.3:0.45:0.075, in this proportion, the gap has been filled through the thick liquid to the regeneration coarse aggregate to utilize top layer film to carry out the secondary protection, the performance can obtain better promotion under the dual function of thick liquid and the outermost layer of cladding film of filling. Comparing example 5 with examples 6-7, it is preferable that the Kim powder is added in an amount of 8% in the cement extravasated Kim powder slurry, and by limiting the addition amount of Kim powder, the content of insoluble needle-like crystals formed by the cement slurry and Kim powder can be controlled, thereby better filling the inner gap of the recycled coarse aggregate and enhancing the durability and service life thereof. Compared with the examples 1 and 8-9, the nano silica sol modified by epoxy groups is preferably added into the polycarboxylic acid high-performance water reducing agent, the cement extravasation Kim powder slurry is matched to fill the coarse aggregate, and the nano silica sol modified by epoxy groups has excellent dispersibility and strong reactivity and can be better mixed with the water reducing agent. In comparative example 1 and examples 10 to 11, it is preferable to use n-butyl titanate in combination with the modified silicone resin, and n-butyl titanate has high reactivity and a good effect of being used in combination with the silicone resin, and can form a film having a better coating property on the surface of the recycled coarse aggregate, thereby greatly reducing the water absorption of the aggregate. Comparing example 1 with example 12, the modified coarse aggregate of example 12 obtained by the preferable combination of examples 1 to 11 has the lowest water absorption rate, the largest apparent density, the performance close to that of natural coarse aggregate and the smallest crushing value, which shows that the interface compactness of the modified aggregate is greatly improved, the compressive strength is improved, and the anti-seepage performance is good.
The specific embodiments are only for explaining the present application and are not limiting to the present application, and those skilled in the art can make modifications to the embodiments without inventive contribution as required after reading the present specification, but all the embodiments are protected by patent law within the scope of the claims of the present application.
Claims (10)
1. The concrete coarse aggregate is characterized by being prepared from the following components in parts by weight:
80-90 parts of regenerated coarse aggregate;
5-15 parts of cement extravasation Kim powder slurry;
0.5-1 part of polycarboxylic acid high-performance water reducing agent;
0.01-0.05 part of nano silicon dioxide sol;
1-5 parts of modified organic silicon resin;
0.01-0.05 part of catalyst;
the modified organic silicon resin comprises the following components in parts by weight: 0.5-2 parts of organic silicon resin; 0.1-0.5 part of active zinc oxide; 0.01-0.05 part of surface treating agent; 0.01-0.02 portion of isopropanol.
2. The concrete coarse aggregate according to claim 1, wherein the preparation of the modified silicone resin comprises the following steps:
step one, mixing and stirring 1-5% of surface treating agent and acetone solution, adding isopropanol, stirring uniformly, adding active zinc oxide, stirring at a high speed for 1.5-2h to mix uniformly, and performing suction filtration and drying on the mixture to obtain modified zinc oxide;
and step two, adding the modified zinc oxide into the organic silicon resin, and mixing and stirring uniformly to obtain the modified organic silicon resin.
3. The concrete coarse aggregate according to claim 2, wherein the surface treatment agent is one of a silane coupling agent KH540, a silane coupling agent KH550 and a silane coupling agent KH-560.
4. The concrete coarse aggregate according to claim 1, wherein the recycled coarse aggregate is: cement extravasation Kim powder slurry: the mass ratio of the modified organic silicon resin is (4-4.5): (0.4-0.5): (0.05-0.1).
5. The concrete coarse aggregate according to claim 1, wherein the Kim powder is blended in the cement extravasation Kim powder slurry in an amount of 5-10%, and the water-cement ratio is 0.6-1.0.
6. The concrete coarse aggregate according to claim 1, wherein the recycled coarse aggregate is prepared by the following steps:
step one, grinding the waste concrete material to obtain a plurality of fragments;
step two, screening the fragments obtained in the step one, and screening the fragments with the particle size of 10-20mm by a screening machine to obtain regenerated coarse aggregate briquettes;
and step three, washing the regenerated coarse aggregate briquettes obtained in the step two with water, and drying for later use.
7. The concrete coarse aggregate according to claim 1, wherein the nano silica sol is one of acrylate modified nano silica sol, methyl modified nano silica sol and epoxy modified nano silica sol.
8. The concrete coarse aggregate according to claim 1, wherein the catalyst is one of n-butyl titanate, tetraisopropyl titanate and ethyl titanate.
9. The method for preparing a concrete coarse aggregate according to any one of claims 1 to 8, characterized by comprising the steps of:
s1, dropwise adding nano silica sol with solid content of 50% into a polycarboxylic acid high-performance water reducing agent, wherein the adding amount is 2-5%, stirring is kept in the adding process to obtain a mixed water reducing agent, and then mixing the mixed water reducing agent with cement extravasation Kim powder slurry by the weight ratio of (0.1-0.2): 1 to obtain modified cement slurry;
and S2, soaking the regenerated coarse aggregate into the modified cement slurry for 3-5 hours, stirring once every 0.5 hour during soaking, taking out the regenerated coarse aggregate, draining excessive cement silica fume slurry, and maintaining for 4 weeks in a standard curing room.
And 10.S3, adding 1-2% of catalyst by mass into the modified organic silicon resin, uniformly stirring, adding water for diluting until the solution concentration is 2-4%, spraying on the surface of the cured regenerated coarse aggregate, and finally drying in a 180 ℃ oven to obtain the concrete coarse aggregate.
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| CN114436601A (en) * | 2022-03-26 | 2022-05-06 | 绍兴市文军砂浆股份有限公司 | Recycled aggregate self-compacting concrete and preparation method thereof |
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| WO2014079086A1 (en) * | 2012-11-21 | 2014-05-30 | 武汉理工大学 | Organic silicone enhancer, recycled aggregate and asphalt mixture and use |
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