CN116947355A - Regenerated coarse aggregate modified by silica sol and preparation method and application thereof - Google Patents
Regenerated coarse aggregate modified by silica sol and preparation method and application thereof Download PDFInfo
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- CN116947355A CN116947355A CN202310693746.4A CN202310693746A CN116947355A CN 116947355 A CN116947355 A CN 116947355A CN 202310693746 A CN202310693746 A CN 202310693746A CN 116947355 A CN116947355 A CN 116947355A
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- coarse aggregate
- recycled
- sodium silicate
- aggregate
- regenerated coarse
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- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 title claims abstract description 36
- 238000002360 preparation method Methods 0.000 title claims abstract description 29
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims abstract description 84
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims abstract description 57
- 239000004115 Sodium Silicate Substances 0.000 claims abstract description 55
- 229910052911 sodium silicate Inorganic materials 0.000 claims abstract description 55
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 46
- 239000000292 calcium oxide Substances 0.000 claims abstract description 23
- 235000012255 calcium oxide Nutrition 0.000 claims abstract description 23
- 239000000843 powder Substances 0.000 claims abstract description 20
- 238000000034 method Methods 0.000 claims abstract description 17
- 238000002791 soaking Methods 0.000 claims description 24
- 238000003756 stirring Methods 0.000 claims description 20
- 239000011148 porous material Substances 0.000 claims description 14
- 238000007605 air drying Methods 0.000 claims description 12
- 238000001914 filtration Methods 0.000 claims description 10
- 239000012466 permeate Substances 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims 5
- 239000002253 acid Substances 0.000 abstract description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 37
- 239000000243 solution Substances 0.000 description 32
- 238000010521 absorption reaction Methods 0.000 description 25
- 230000004048 modification Effects 0.000 description 19
- 238000012986 modification Methods 0.000 description 19
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 12
- 238000011056 performance test Methods 0.000 description 12
- 238000012360 testing method Methods 0.000 description 11
- 239000002699 waste material Substances 0.000 description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 8
- 239000012535 impurity Substances 0.000 description 7
- 239000002994 raw material Substances 0.000 description 7
- 238000005406 washing Methods 0.000 description 7
- 238000010276 construction Methods 0.000 description 6
- 239000012634 fragment Substances 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 239000000377 silicon dioxide Substances 0.000 description 5
- 235000012239 silicon dioxide Nutrition 0.000 description 5
- 239000013078 crystal Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000001965 increasing effect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 230000000051 modifying effect Effects 0.000 description 3
- 239000005543 nano-size silicon particle Substances 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000013065 commercial product Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000011010 flushing procedure Methods 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 102100040791 Zona pellucida-binding protein 1 Human genes 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229910052910 alkali metal silicate Inorganic materials 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- VSGNNIFQASZAOI-UHFFFAOYSA-L calcium acetate Chemical compound [Ca+2].CC([O-])=O.CC([O-])=O VSGNNIFQASZAOI-UHFFFAOYSA-L 0.000 description 1
- 239000001639 calcium acetate Substances 0.000 description 1
- 235000011092 calcium acetate Nutrition 0.000 description 1
- 229960005147 calcium acetate Drugs 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 235000011116 calcium hydroxide Nutrition 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000011083 cement mortar Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- XJKVPKYVPCWHFO-UHFFFAOYSA-N silicon;hydrate Chemical compound O.[Si] XJKVPKYVPCWHFO-UHFFFAOYSA-N 0.000 description 1
- 235000019795 sodium metasilicate Nutrition 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000010257 thawing Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- 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
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
-
- 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
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/10—Coating or impregnating
- C04B20/1055—Coating or impregnating with inorganic materials
- C04B20/1074—Silicates, e.g. glass
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
Abstract
The application discloses a regenerated coarse aggregate modified by silica sol and a preparation method and application thereof, wherein the regenerated coarse aggregate is immersed in a hydrated sodium silicate solution with the mass concentration of 40-60%, kept stand, soaked for 9-12 h, soaked for 5-10 min by using a dilute acetic acid solution with the mass concentration of 6-13%, naturally air-dried for 1 h to obtain a pretreated regenerated coarse aggregate, and finally poured into a stirrer to be fully stirred with quicklime powder to obtain the silica sol modified regenerated coarse aggregate. The application solves the problems that the prior treatment method has low early strength of the surface modified sodium silicate and can be coagulated and solidified after about 20 days; the low-concentration acetic acid weak acid is used, so that sodium silicate can be fully converted into silica sol, residual acetic acid can also react with quicklime, the surface strength of aggregate is improved, and the crushing index is reduced.
Description
Technical Field
The application belongs to the field of civil engineering materials, and particularly relates to a regenerated coarse aggregate modified by silica sol, and a preparation method and application thereof.
Background
Since the last century, the construction industry has rapidly developed, and a large amount of construction waste is generated after the construction is aged and removed until the service life of a plurality of buildings in the century expires, and the demand of concrete is continuously increased at present, so that the contradiction between resource environment and energy is continuously activated, the construction waste is reused to replace natural sand stone as construction aggregate, and the construction method is an important way for delaying the contradiction between resources and environmental demands. But the recycled aggregate has low quality, and is characterized by low apparent density, high crushing index, high water absorption and high porosity, and the surface is often covered with a layer of cement paste, thus greatly influencing the reutilization in the concrete. How to modify the recycled aggregate, the physical and mechanical properties of the recycled aggregate are improved, and the method has economic benefit and environmental protection value for popularization and application of the recycled aggregate.
In order to improve the utilization rate of recycled aggregate, many reports about modified recycled aggregate are provided, for example, publication No. CN202010203705.9, "a recycled concrete and a preparation method thereof", discloses a method for modifying recycled aggregate by adopting a sodium silicate solution and a polyvinyl alcohol solution, filling in gaps of concrete waste materials and enhancing the mechanical properties of concrete, but the used silica dispersion liquid has low concentration, low early strength and low setting and curing speed. Publication No. CN 202010631719.0 discloses a method for preparing recycled aggregate modified by nano silicon dioxide and application thereof, wherein the method comprises the steps of immersing coarse aggregate in hydrochloric acid solution, taking out, draining, and adding sodium silicate or sodium metasilicate for surface modification, wherein the method comprises the steps of damaging the stressed structure of the recycled aggregate by using hydrochloric acid, and damaging the microstructure of the recycled aggregate by using hydrochloric acid, so that the modification effect of sodium silicate is influenced.
Disclosure of Invention
This section is intended to outline some aspects of embodiments of the application and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section as well as in the description of the application and in the title of the application, which may not be used to limit the scope of the application.
The present application has been made in view of the above and/or problems occurring in the prior art.
Therefore, the application aims to overcome the defects in the prior art and provide a preparation method of the regenerated coarse aggregate modified by silica sol.
In order to solve the technical problems, the application provides the following technical scheme: a method for preparing regenerated coarse aggregate modified by silica sol comprises,
immersing the recycled coarse aggregate in a hydrated sodium silicate solution, standing, and fishing out and draining when sodium silicate permeates micro pores in the recycled coarse aggregate and adheres to the surface of the recycled coarse aggregate to prepare the sodium silicate treated recycled coarse aggregate;
soaking the regenerated coarse aggregate treated by sodium silicate in dilute acetic acid solution, standing, filtering, and naturally air-drying to obtain pretreated regenerated coarse aggregate;
fully stirring the pretreated regenerated coarse aggregate and quicklime powder to obtain the silica sol modified regenerated coarse aggregate.
As a preferred embodiment of the preparation process according to the application, there is provided: the recycled aggregate is three-stage recycled coarse aggregate, and the particle size of the recycled aggregate is 5-20 mm.
As a preferred embodiment of the preparation process according to the application, there is provided: the mass concentration of the hydrated sodium silicate solution is 40% -60%.
As a preferred embodiment of the preparation process according to the application, there is provided: immersing the regenerated coarse aggregate in a hydrated sodium silicate solution for standing, wherein the standing time is 9-12 h.
As a preferred embodiment of the preparation process according to the application, there is provided: the concentration of the dilute acetic acid solution is 6% -13%.
As a preferred embodiment of the preparation process according to the application, there is provided: and soaking the regenerated coarse aggregate treated by the sodium silicate in a dilute acetic acid solution, wherein the soaking time is 5-10 min.
As a preferred embodiment of the preparation process according to the application, there is provided: and naturally air-drying, wherein the air-drying time is 1-5 hours.
As a preferred embodiment of the preparation process according to the application, there is provided: the pretreated regenerated coarse aggregate and the quicklime powder are fully stirred, wherein the mass ratio of the pretreated regenerated coarse aggregate to the quicklime powder is 15-20:1, the stirring speed is 10-20 r/min, and the stirring time is 1-5 min.
It is still another object of the present application to provide a recycled coarse aggregate prepared by the preparation method of a silica sol modified recycled coarse aggregate, which overcomes the disadvantages of the prior art.
The application further aims to overcome the defects in the prior art and provide an application of the recycled coarse aggregate prepared by the preparation method of the silica sol modified recycled coarse aggregate in preparing concrete.
The application has the beneficial effects that:
(1) Compared with the nano silicon dioxide modified solution, the sodium silicate solution is used as the raw material, and the cost is lower; compared with nano silicon dioxide dispersion liquid, the high-concentration sodium silicate solution has stronger permeability, is easier to fill microscopic pores in the recycled coarse aggregate, and can be decomposed into silicon dioxide and water when being heated, so that the silicon dioxide can be better dispersed in the aggregate, the compression resistance of the recycled aggregate is improved, and the porosity is reduced.
(2) The modified coarse aggregate has the advantages of reduced water absorption, relatively hard internal structure, and higher bonding strength with a cement mortar interface transition area, thereby being beneficial to improving the strength of concrete; after the recycled aggregate with small water absorption rate is prepared into the hardened concrete, the internal defect pores are less than those of the concrete with large water absorption rate, so that the free water content in the concrete pores is less, the durability of the concrete is improved, and the freeze thawing damage is not easy to occur; meanwhile, the product has the advantages of lower preparation cost, simple process and practicability, and can be widely popularized.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:
FIG. 1 is a diagram of silica sol modified recycled coarse aggregate in an embodiment of the application.
Detailed Description
In order that the above-recited objects, features and advantages of the present application will become more apparent, a more particular description of the application will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, but the present application may be practiced in other ways other than those described herein, and persons skilled in the art will readily appreciate that the present application is not limited to the specific embodiments disclosed below.
Further, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic can be included in at least one implementation of the application. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
The recycled aggregate in the embodiment of the application is three-level recycled coarse aggregate, the grain size of which is 5-20 mm, and the recycled aggregate is a common commercial product;
the model of the hydrated sodium silicate is SP38, the modulus of the hydrated sodium silicate is 3.30, and the used product is a product of refractory material Limited company in Jiashan county and is a common commercial product.
Example 1
The embodiment provides a preparation method of recycled coarse aggregate modified by silica sol, which mainly comprises the following steps:
(1) Preparing recycled aggregate raw materials: hydrated sodium silicate with the mass concentration of 40% and diluted acetic acid with the mass concentration of 6% are sufficient, and quicklime powder is sufficient.
(2) Immersing the recycled coarse aggregate in a high-concentration sodium silicate solution, standing, and fishing out and draining when sodium silicate permeates micro pores in the recycled coarse aggregate and adheres to the surface of the recycled coarse aggregate;
(3) Soaking the recycled coarse aggregate treated in the step (2) in a dilute acetic acid solution and standing;
(4) Salvaging the recycled coarse aggregate treated in the step (3), washing with water to remove surface impurities, filtering, and naturally air-drying to obtain pretreated recycled coarse aggregate;
(5) Pouring the pretreated regenerated coarse aggregate into a stirrer with the rotating speed of 10-20 rad/min and the stirring time of 1-5 min, and fully stirring with quicklime powder to obtain the silica sol modified regenerated coarse aggregate.
In this example, the performance test was carried out with reference to the requirements specified in "recycled aggregate application technical Specification" (JGJ/T240-2011).
In the test, the obtained concrete has the following relevant performance test results:
apparent density before modification of 2263kg/m 3 Suction pipeThe water ratio is 10.3%, and the crushing index is 24%;
the apparent density after modification is 2266kg/m 3 The water absorption is 7.0%, the water absorption is reduced by 32%, the crushing index is 19%, and the crushing index is reduced by 21%.
Example 2
The embodiment provides a preparation method of recycled coarse aggregate modified by silica sol, which mainly comprises the following steps:
(1) Preparing recycled aggregate raw materials: the sodium silicate hydrate with the mass concentration of 50 percent and the dilute acetic acid with the mass concentration of 9 percent are sufficient, and the quicklime powder is sufficient.
(2) Immersing the recycled coarse aggregate in a high-concentration sodium silicate solution for standing, and fishing out and draining when sodium silicate permeates micro pores in the recycled coarse aggregate and adheres to the surface of the recycled coarse aggregate;
(3) Soaking the recycled coarse aggregate treated in the step (2) in a dilute acetic acid solution;
(4) Salvaging the recycled coarse aggregate treated in the step (3), washing with water to remove surface impurities, filtering, and naturally air-drying to obtain pretreated recycled coarse aggregate;
(5) Pouring the pretreated regenerated coarse aggregate into a stirrer with the rotating speed of 10-20 rad/min and the stirring time of 1-5 min, and fully stirring with quicklime powder to obtain the silica sol modified regenerated coarse aggregate.
In this example, the performance test was carried out with reference to the requirements specified in "recycled aggregate application technical Specification" (JGJ/T240-2011).
In the test, the obtained concrete has the following relevant performance test results:
apparent density before modification of 2265kg/m 3 The water absorption is 10.3 percent, and the crushing index is 26 percent;
the apparent density after modification is 2267kg/m 3 The water absorption is 6.7%, the water absorption is reduced by 34%, the crushing index is 19%, and the crushing index is reduced by 27%.
Example 3
The embodiment provides a preparation method of recycled coarse aggregate modified by silica sol, which mainly comprises the following steps:
(1) Preparing recycled aggregate raw materials: 58% of hydrated sodium silicate, 13% of diluted acetic acid and lime powder.
(2) Immersing the recycled coarse aggregate in a high-concentration sodium silicate solution for standing, and fishing out and draining when sodium silicate permeates micro pores in the recycled coarse aggregate and adheres to the surface of the recycled coarse aggregate;
(3) Soaking the recycled coarse aggregate treated in the step (2) in a dilute acetic acid solution;
(4) Salvaging the recycled coarse aggregate treated in the step (3), washing with water to remove surface impurities, filtering, and naturally air-drying to obtain pretreated recycled coarse aggregate;
(5) Pouring the pretreated regenerated coarse aggregate into a stirrer with the rotating speed of 10-20 rad/min and the stirring time of 1-5 min, and fully stirring with quicklime powder to obtain the silica sol modified regenerated coarse aggregate, wherein the prepared physical diagram is shown in figure 1.
In this example, the performance test was carried out with reference to the requirements specified in "recycled aggregate application technical Specification" (JGJ/T240-2011).
In the test, the obtained concrete has the following relevant performance test results:
apparent density before modification of 2262kg/m 3 The water absorption is 10.3 percent, and the crushing index is 27 percent;
the apparent density after modification is 2265kg/m 3 The water absorption is 6.7%, the water absorption is reduced by 35%, the crushing index is 19.7%, and the crushing index is reduced by 26%.
Comparative example 1
The comparative example provides a preparation method of recycled coarse aggregate modified by silica sol, which mainly comprises the following steps:
(1) Preparing recycled aggregate raw materials: hydrated sodium silicate with the mass concentration of 40% and diluted acetic acid with the mass concentration of 20% are sufficient, and quicklime powder is sufficient.
(2) Immersing the recycled coarse aggregate in a high-concentration sodium silicate solution, standing, and fishing out and draining when sodium silicate permeates micro pores in the recycled coarse aggregate and adheres to the surface of the recycled coarse aggregate;
(3) Soaking the recycled coarse aggregate treated in the step (2) in a dilute acetic acid solution and standing;
(4) Salvaging the recycled coarse aggregate treated in the step (3), washing with water to remove surface impurities, filtering, and naturally air-drying to obtain pretreated recycled coarse aggregate;
(5) Pouring the pretreated regenerated coarse aggregate into a stirrer with the rotating speed of 10-20 rad/min and the stirring time of 1-5 min, and fully stirring with quicklime powder to obtain the silica sol modified regenerated coarse aggregate.
Performance testing is determined with reference to requirements specified in recycled aggregate application Specification (JGJ/T240-2011).
In the test, the obtained concrete has the following relevant performance test results:
apparent density before modification of 2263kg/m 3 The water absorption is 10.3 percent, and the crushing index is 25 percent;
the apparent density after modification is 2266kg/m 3 The water absorption is 8.7%, the water absorption is reduced by 15%, the crushing index is 20%, and the crushing index is reduced by 25%.
Comparative example 2
The comparative example provides a preparation method of recycled coarse aggregate modified by silica sol, which mainly comprises the following steps:
(1) Preparing recycled aggregate raw materials: the hydrated sodium silicate solution with the mass concentration of 20 percent and the diluted acetic acid with the mass concentration of 8 percent are sufficient, and the quicklime powder is sufficient.
(2) Immersing the recycled coarse aggregate in a high-concentration sodium silicate solution for standing, and fishing out and draining when sodium silicate permeates micro pores in the recycled coarse aggregate and adheres to the surface of the recycled coarse aggregate;
(3) Soaking the recycled coarse aggregate treated in the step (2) in a dilute acetic acid solution;
(4) Salvaging the recycled coarse aggregate treated in the step (3), washing with water to remove surface impurities, filtering, and naturally air-drying to obtain pretreated recycled coarse aggregate;
(5) Pouring the pretreated regenerated coarse aggregate into a stirrer with the rotating speed of 10-20 rad/min and the stirring time of 1-5 min, and fully stirring with quicklime powder to obtain the silica sol modified regenerated coarse aggregate.
Performance testing is determined with reference to requirements specified in recycled aggregate application Specification (JGJ/T240-2011). In the test, the obtained concrete has the following relevant performance test results:
apparent density before modification of 2262kg/m 3 The water absorption is 10.3 percent, and the crushing index is 27 percent;
the apparent density after modification is 2263kg/m 3 The water absorption is 8.2%, the water absorption is reduced by 20.3%, the crushing index is 25%, and the crushing index is reduced by 7%.
Comparative example 3
The comparative example provides a recycled concrete and a preparation method thereof, wherein the preparation method of the recycled concrete aggregate comprises the following steps:
(1) Crushing: crushing the concrete waste after surface impurity removal, selecting concrete waste fragments with the diameter of 5-25 mm, and flushing the concrete waste fragments with running water for 15min;
(2) Soaking: after the washed concrete waste fragments are dried, the ratio of the materials to the liquid is 1:3, soaking in hydrochloric acid solution with the mass fraction of 2wt% for 2 hours, and taking out soaked concrete waste fragments for drying after the soaking is finished;
(3) The dried concrete waste fragments are mixed according to a feed liquid ratio of 1:3, soaking in 10wt% sodium silicate aqueous solution for 24 hours, continuously stirring during the soaking process, filtering after the soaking is finished, and washing for 10 minutes by using running water;
(4) After the surface of the concrete waste fragments is dried, the ratio of the materials to the liquid is 1:2 soaking in a polyvinyl alcohol solution with the mass fraction of 5wt% for 24 hours, continuously stirring in the soaking process, filtering after the soaking is finished, and flushing for 30 minutes by using running water to obtain the recycled concrete aggregate.
Performance testing is determined with reference to requirements specified in recycled aggregate application Specification (JGJ/T240-2011). In the test, the obtained concrete has the following relevant performance test results:
apparent density before modification of 2262kg/m 3 The water absorption is 10.3%, and the crushing refers toMarked 27%;
the apparent density after modification is 2265kg/m 3 The water absorption is 10.7%, the water absorption is improved by 3.8%, the crushing index is 32%, and the crushing index is improved by 18.5%.
Comparative example 4
The embodiment provides a preparation method of recycled coarse aggregate modified by silica sol, which mainly comprises the following steps:
(1) Preparing recycled aggregate raw materials: 58% of hydrated sodium silicate, 20% of diluted acetic acid and lime powder.
(2) Immersing the recycled coarse aggregate in a high-concentration sodium silicate solution for standing, and fishing out and draining when sodium silicate permeates micro pores in the recycled coarse aggregate and adheres to the surface of the recycled coarse aggregate;
(3) Soaking the recycled coarse aggregate treated in the step (2) in a dilute acetic acid solution;
(4) Salvaging the recycled coarse aggregate treated in the step (3), washing with water to remove surface impurities, filtering, and naturally air-drying to obtain pretreated recycled coarse aggregate;
(5) Pouring the pretreated regenerated coarse aggregate into a stirrer with the rotating speed of 10-20 rad/min and the stirring time of 1-5 min, and fully stirring with quicklime powder to obtain the silica sol modified regenerated coarse aggregate.
In this example, the performance test was carried out with reference to the requirements specified in "recycled aggregate application technical Specification" (JGJ/T240-2011).
In the test, the obtained concrete has the following relevant performance test results:
apparent density before modification of 2263kg/m 3 The water absorption is 10.3 percent, and the crushing index is 27 percent;
the apparent density after modification is 2265kg/m 3 The water absorption is 8.4%, the water absorption is reduced by 18%, the crushing index is 19%, and the crushing index is reduced by 18.5%.
The results of the performance tests of the inventive examples and comparative examples are shown in table 1.
TABLE 1
As can be seen from the test results in Table 1, the regenerated coarse aggregate modified by silica sol and the preparation method thereof provided by the application have the advantages that the water absorption and crushing index of the aggregate are optimized after the surface modification is carried out by the chemical reaction of the fully quicklime through soaking in sodium silicate with the mass concentration of 40% -61% and dilute acetic acid with the mass concentration of 6% -13%.
According to the method, the regenerated coarse aggregate is soaked in the sodium silicate solution, sodium silicate is enabled to permeate into micro-pores in the regenerated coarse aggregate by utilizing the permeability of the sodium silicate, silica sol is generated in the micro-pores in the regenerated coarse aggregate by utilizing dilute acetic acid, silicate gel is decorated on the surface of the regenerated aggregate, the silica sol in the aggregate is heated to form high-strength ceramic structure silica crystals by mixing with quicklime powder, silicate and slaked lime are generated by attaching the surface of the silica sol, and calcium acetate crystals are partially covered. When the acetic acid concentration is high or the soaking time is too long, the acidic environment can damage the internal structure of the aggregate and influence the surface modification, so that the strength is not increased and reduced, which is proved in comparative example 1 and examples.
As can be seen from comparative example 3 and table 1, sodium silicate does not increase the strength of the recycled aggregate itself, but rather, the silicate gel generated by Alkali Silicate Reaction (ASR) causes the volume change inside the recycled aggregate to cause the internal structure to be destroyed, and only sodium silicate reacts with air to generate silica crystals, which can exert the effect of increasing the strength, resulting in inferior properties to those of examples 1 to 3.
As is clear from comparative examples 1 to 3 and comparative example 2, the higher the concentration of sodium silicate hydrate, the better the modifying effect, and the stability tends to be high at a concentration of more than 50%.
According to the application, the fluidity and the permeability of hydrated sodium silicate are utilized to enable sodium silicate to permeate into the pores inside the recycled aggregate, then the sodium silicate inside the aggregate is converted into silica sol through the soaking of acetic acid, and colloid silicic acid is attached to the surface of the aggregate; meanwhile, calcium silicate particles are modified on the surface of the aggregate by mixing the silica sol with quicklime, and the silica sol in the aggregate forms high-strength ceramic structure silica crystals due to the fact that the quicklime reacts with residual moisture on the surface of the aggregate and reacts with acetic acid to release heat in the mixing process.
In summary, in order to solve the problems of low efficiency, high cost, unobvious modification effect and low early strength of the coagulation and solidification of sodium silicate in the prior art, the application provides a method for modifying recycled coarse aggregate by utilizing silica sol. The method solves the problems that the prior treatment method has low early strength of the surface modified sodium silicate and can be coagulated and solidified after about 20 days; the low-concentration acetic acid weak acid is used, so that sodium silicate can be fully converted into silica sol, residual acetic acid can also react with quicklime, the surface strength of aggregate is improved, and the crushing index is reduced.
It should be noted that the above embodiments are only for illustrating the technical solution of the present application and not for limiting the same, and although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present application may be modified or substituted without departing from the spirit and scope of the technical solution of the present application, and it should be covered in the scope of the present application.
Claims (10)
1. The preparation method of the regenerated coarse aggregate modified by silica sol is characterized by comprising the following steps of: comprising the steps of (a) a step of,
immersing the recycled coarse aggregate in a hydrated sodium silicate solution, standing, and fishing out and draining when sodium silicate permeates micro pores in the recycled coarse aggregate and adheres to the surface of the recycled coarse aggregate to prepare the sodium silicate treated recycled coarse aggregate;
soaking the regenerated coarse aggregate treated by sodium silicate in dilute acetic acid solution, standing, filtering, and naturally air-drying to obtain pretreated regenerated coarse aggregate;
fully stirring the pretreated regenerated coarse aggregate and quicklime powder to obtain the silica sol modified regenerated coarse aggregate.
2. The method of manufacturing according to claim 1, wherein: the recycled aggregate is three-stage recycled coarse aggregate, and the particle size of the recycled aggregate is 5-20 mm.
3. The preparation method according to claim 1 or 2, characterized in that: the mass concentration of the hydrated sodium silicate solution is 40% -60%.
4. A method of preparation as claimed in claim 3, wherein: immersing the regenerated coarse aggregate in a hydrated sodium silicate solution for standing, wherein the standing time is 9-12 h.
5. The method of manufacturing according to claim 1, wherein: the concentration of the dilute acetic acid solution is 6% -13%.
6. The method of manufacturing according to claim 5, wherein: and soaking the regenerated coarse aggregate treated by the sodium silicate in a dilute acetic acid solution, wherein the soaking time is 5-10 min.
7. The method of manufacturing according to claim 1, wherein: and naturally air-drying, wherein the air-drying time is 1-5 hours.
8. The method of claim 1 or 7, wherein: the pretreated regenerated coarse aggregate and the quicklime powder are fully stirred, wherein the mass ratio of the pretreated regenerated coarse aggregate to the quicklime powder is 15-20:1, the stirring speed is 10-20 r/min, and the stirring time is 1-5 min.
9. A recycled coarse aggregate produced by the production method according to any one of claims 1 to 8.
10. Use of recycled coarse aggregate according to claim 9 for the preparation of concrete.
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| CN113582570A (en) * | 2021-06-01 | 2021-11-02 | 河北工程大学 | Method for repeatedly strengthening recycled concrete aggregate |
| CN115321860A (en) * | 2022-07-29 | 2022-11-11 | 中原环保万瑞郑州固废科技有限公司 | Construction waste recycled aggregate surface modification and particle reinforcement method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113582570A (en) * | 2021-06-01 | 2021-11-02 | 河北工程大学 | Method for repeatedly strengthening recycled concrete aggregate |
| CN115321860A (en) * | 2022-07-29 | 2022-11-11 | 中原环保万瑞郑州固废科技有限公司 | Construction waste recycled aggregate surface modification and particle reinforcement method |
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