CN112608092A - Dry-mixed ground mortar prepared from recycled aggregate and preparation method thereof - Google Patents
Dry-mixed ground mortar prepared from recycled aggregate and preparation method thereof Download PDFInfo
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- CN112608092A CN112608092A CN202010736410.8A CN202010736410A CN112608092A CN 112608092 A CN112608092 A CN 112608092A CN 202010736410 A CN202010736410 A CN 202010736410A CN 112608092 A CN112608092 A CN 112608092A
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00017—Aspects relating to the protection of the environment
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/60—Flooring materials
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
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Abstract
The invention provides dry-mixed ground mortar prepared by utilizing recycled aggregate and a preparation method thereof, wherein the preparation method comprises the following steps: crushing, refining, cleaning and screening the construction waste to obtain recycled fine aggregate; modifying the recycled fine aggregate by using polyether polyol, sodium silicate and a coupling agent to obtain modified recycled fine aggregate; and weighing the ordinary portland cement, the modified recycled fine aggregate, the class II fly ash, the modified palygorskite, the redispersible latex powder, the starch ether, the water reducing agent and the sodium gluconate according to the parts by weight, and uniformly mixing to obtain the dry-mixed ground mortar. By modifying the recycled fine aggregate, the 28d compressive strength of the obtained modified recycled fine aggregate dry-mixed ground mortar is improved by nearly 20%, the water retention rate is improved by about 17%, the setting time is improved by about 9%, the 2h consistency loss rate is reduced by about 32%, the performance of the modified recycled fine aggregate dry-mixed ground mortar is equivalent to that of natural river sand dry-mixed ground mortar, even slightly superior, and the resource utilization of the construction waste is realized.
Description
Technical Field
The invention relates to the technical field of resource utilization of construction waste and production of building materials, in particular to dry-mixed ground mortar prepared by utilizing recycled aggregate and a preparation method thereof.
Background
Aggregate formed by crushing and grading construction waste (mainly comprising waste concrete, waste bricks and the like) is called recycled concrete aggregate, and is called recycled aggregate for short. With the improvement of environmental awareness of modern society, people pay more and more attention to the problem of recycling a large amount of waste concrete generated in the building industry. The development and application of the recycled concrete aggregate can greatly utilize the waste concrete and reduce the consumption of the natural aggregate in the construction industry; on the other hand, the problems of the gradual deterioration of the ecological environment and the like caused by concrete waste can be reduced, and the sustainable development of the human society is ensured.
However, compared with natural aggregate, the recycled aggregate has the characteristics of low strength, more corner cracks, high surface inerting degree, high porosity, high water absorption, high mud content and the like, and the working performance, mechanical property and durability of the recycled cement product prepared by the recycled aggregate are difficult to meet the engineering requirements. The recycled aggregate is mainly used for manufacturing medium-low-strength concrete at present, has a narrow application range, and is generally used for road engineering cushion layers, plain concrete cushion layers, large-volume concrete, low-strength concrete of non-load-bearing structures and the like. If the application range is widened, the recycled aggregate needs to be activated and strengthened, and the strength of the recycled aggregate is improved.
At present, research reports and patents on reinforcing aggregate performance by using a binder, a waterproof agent and the like are reported, but the concrete raw materials adopted in these publications are all from natural river sand, and the strength, waterproof performance and the like of the concrete are further enhanced on the basis of the natural river sand. However, the concrete in the construction and removal waste has been used for decades, and the recycled aggregate prepared from the concrete has the characteristics of low strength, more corner cracks, high surface inerting degree, high porosity, high water absorption, high mud content and the like, and the technical difficulty of activating and strengthening the recycled aggregate is higher, so that the existing literature method is not suitable for the recycled aggregate.
Therefore, it is urgently needed to provide a method for effectively activating and strengthening recycled aggregate, so that the recycled aggregate can be applied to dry-mixed ground mortar instead of natural sand.
Disclosure of Invention
The invention aims to provide a method for preparing dry-mixed ground mortar by using recycled fine aggregate to replace natural sand, so as to solve the problems of more cracks, low strength and narrow application range of the conventional recycled fine aggregate.
To achieve the above object, according to a first aspect of the present invention, there is provided a method for preparing a dry-mixed floor mortar using recycled aggregate, comprising the steps of:
(1) preparing modified recycled fine aggregate:
a. repeatedly crushing, refining, cleaning and screening the construction waste to obtain recycled fine aggregate with the particle size of 0.08-4.75 mm;
b. weighing polyether polyol and sodium silicate according to the weight parts, uniformly mixing, adding water, fully stirring and dissolving to obtain a modified slurry solution;
c. uniformly spraying the modified slurry solution on the surface of the recycled fine aggregate under stirring, so that the surface of the recycled fine aggregate is soaked by the modified slurry solution, the modified slurry solution fully permeates into microcracks of the recycled fine aggregate, and then standing and airing to obtain pretreated fine aggregate;
d. dissolving a coupling agent in absolute ethyl alcohol to prepare a coupling agent alcohol solution;
e. placing the pretreated fine aggregate into a high-speed mixer, pumping a coupling agent alcohol solution in a fine mist shape under stirring, stirring for 10-30 min, and preparing the modified recycled fine aggregate after absolute ethyl alcohol is completely volatilized;
(2) preparing dry-mixed ground mortar:
weighing and uniformly mixing ordinary portland cement, modified recycled fine aggregate, class II fly ash, modified palygorskite, redispersible latex powder, starch ether, water reducing agent and sodium gluconate according to the weight parts to obtain the dry-mixed ground mortar.
In a preferred embodiment of the invention, the mass ratio of the polyether polyol, the sodium silicate and the water is 0.5-2: 3-5: 100.
In a preferred embodiment of the invention, the mass ratio of the coupling agent to the absolute ethyl alcohol is 0.2-1.5: 100.
In a preferred embodiment of the invention, the mass ratio of the ordinary portland cement, the modified recycled fine aggregate, the class II fly ash, the modified palygorskite, the redispersible latex powder, the starch ether, the water reducing agent and the sodium gluconate is 170-200: 700-900: 10-40: 1-3: 1-4: 0.01-0.04: 0.1-0.2: 0.05-0.2.
In a preferred embodiment of the present invention, the construction waste is one or more of construction waste concrete, waste masonry, crushed stone, crushed brick and tile, and waste mortar.
In a preferred embodiment of the invention, the polyether polyol is PEG or PPG, and the molecular weight is 200-5000.
In a preferred embodiment of the present invention, the coupling agent is one or more of mercaptopropyltrimethoxysilane, anilinomethyltrimethoxysilane, isopropyltris (dioctylpyrophosphate) titanate and 3- (methacryloyloxy) propyltrimethoxysilane.
In a preferred embodiment of the invention, the redispersible latex powder is one or more of polyethylene vinyl acetate, polyvinyl acetate-vinyl versatate, polystyrene-acrylate, and polyacrylate.
In a preferred embodiment of the present invention, the water reducing agent is one or more of lignin-based water reducing agent powder, naphthalene-based water reducing agent powder, and polycarboxylic acid water reducing agent powder.
In a preferred embodiment of the present invention, the modified palygorskite has a fineness of 400 to 1000 mesh.
In a second aspect of the present invention, there is provided a dry-mixed floor mortar prepared using recycled aggregate, the dry-mixed floor mortar being prepared by the method of the first aspect of the present invention.
The invention has the advantages of
Different from the prior art, the technical scheme activates and strengthens the recycled aggregate formed by the waste construction waste, so that the recycled aggregate can replace natural sand to be applied to dry-mixed ground mortar, and the resource utilization of the construction waste is realized. Specifically, the technical scheme has the following beneficial effects:
(1) according to the technical scheme, the construction waste is repeatedly crushed, refined, cleaned and screened, the aim is to effectively remove fragile edges and corners on aggregate particles and hardened mortar adhered to the surfaces of broken stones by adopting a mechanical activation treatment mode, the performance of the aggregate is improved, and then the high-quality recycled fine aggregate with the particle size of 0.08-4.75 mm is obtained by screening and grading.
(2) The technical scheme is that the regenerated fine aggregate is sprayed by the polyether polyol and the sodium silicate aqueous solution, the surface of the regenerated fine aggregate is infiltrated by the polyether polyol and the sodium silicate aqueous solution in the stirring process, and the polyether polyol and the sodium silicate aqueous solution fully penetrate into microcracks of the regenerated fine aggregate, wherein the sodium silicate and cement hydration products Ca (OH) on the surface of the regenerated fine aggregate2The calcium silicate colloid is generated by reaction, the generated calcium silicate colloid effectively fills the microcracks of the recycled fine aggregate, and the porosity of the recycled fine aggregate is effectively reduced, so that the compactness of the recycled fine aggregate is greatly improved.
(3) According to the technical scheme, the coupling agent is adopted, a bridging structure of a fine aggregate interface-coupling agent-polyether polyol-coupling agent-aggregate interface is formed in pores and microcracks of the recycled fine aggregate, and the effects of filling the pores of the recycled fine aggregate, bonding the cracks of the recycled aggregate, toughening and reinforcing and inhibiting crack expansion are achieved, so that the problems of low aggregate strength, high porosity, high water absorption and poor impermeability caused by the existence of microcracks after stress of the aggregate in the process of recycling and crushing are solved, and the performance of the recycled fine aggregate is improved.
(4) According to the technical scheme, the recycled fine aggregate is modified and enhanced, various properties of the recycled fine aggregate reach the properties of the natural fine aggregate, and part of the properties are even better than those of the natural fine aggregate.
(5) In the technical scheme, the starch ether and the modified palygorskite are water-retaining thickening materials of dry-mixed ground mortar, and can improve the viscosity and the water-retaining property of the mortar. Palygorskite is a water-containing magnesium-rich silicate clay mineral with a fibrous texture lamellar chain transition structure. The modified palygorskite is an intricately crossed bundle-shaped aggregate formed by needle-shaped crystal fibers, the bundle-shaped aggregate can wrap large particles such as sand in mortar so as to prevent the sand from settling in the mortar, and the modified palygorskite can also improve the viscosity, the water retention rate and the thixotropy of the mortar.
(6) According to the technical scheme, the redispersible rubber powder is added into the dry-mixed ground mortar formula, so that the breaking strength, the bonding strength and the wear resistance of the ground mortar can be improved, and the shrinkage rate of the mortar can be reduced. Both the cement and the redispersible gelatine powder have the function of a binding material, the former forming a hydrated product by chemical reaction with the water used for mixing, the latter acting by film formation during drying. This complementary binding mechanism provides stability and safety to the overall system.
(7) According to the technical scheme, the water reducing agent is added into the dry-mixed ground mortar formula, so that the mortar has high fluidity and stability. In addition, the addition of sodium gluconate as a retarder makes it possible to adjust the setting time.
Detailed Description
A method for preparing a dry-mixed floor mortar using recycled aggregate according to the first aspect of the present invention and a dry-mixed floor mortar using recycled aggregate according to the second aspect of the present invention will be described in detail below.
First, a method for preparing a dry-mixed floor mortar using recycled aggregate according to a first aspect of the present invention will be described, which comprises the steps of:
(1) preparing modified recycled fine aggregate:
a. repeatedly crushing, refining, cleaning and screening the construction waste to obtain recycled fine aggregate with the particle size of 0.08-4.75 mm;
b. weighing polyether polyol and sodium silicate according to the weight parts, uniformly mixing, adding water, fully stirring and dissolving to obtain a modified slurry solution;
c. uniformly spraying the modified slurry solution on the surface of the recycled fine aggregate under stirring, so that the surface of the recycled fine aggregate is soaked by the modified slurry solution, the modified slurry solution fully permeates into microcracks of the recycled fine aggregate, and then standing and airing to obtain pretreated fine aggregate;
d. dissolving a coupling agent in absolute ethyl alcohol to prepare a coupling agent alcohol solution;
e. placing the pretreated fine aggregate into a high-speed mixer, pumping a coupling agent alcohol solution in a fine mist shape under stirring, stirring for 10-30 min, and preparing the modified recycled fine aggregate after absolute ethyl alcohol is completely volatilized;
(2) preparing dry-mixed ground mortar:
weighing and uniformly mixing ordinary portland cement, modified recycled fine aggregate, class II fly ash, modified palygorskite, redispersible latex powder, starch ether, water reducing agent and sodium gluconate according to the weight parts to obtain the dry-mixed ground mortar.
According to the technical scheme, the construction waste is repeatedly crushed, refined, cleaned and screened, the aim is to effectively remove fragile edges and corners on aggregate particles and hardened mortar adhered to the surfaces of broken stones by adopting a mechanical activation treatment mode, the performance of the aggregate is improved, and then the high-quality recycled fine aggregate with the particle size of 0.08-4.75 mm is obtained by screening and grading. The surface of the recycled fine aggregate which is not modified contains a large amount of microcracks, so that the recycled aggregate has high porosity and high water absorption. The technical scheme adopts polyether polyol, sodium silicate and a coupling agent to modify the recycled fine aggregate, wherein the sodium silicate can be mixed with a cement hydration product Ca (OH) on the surface of the recycled fine aggregate2Reacting to generate calcium silicate colloid to effectively fill recycled fine aggregateThe micro-cracks reduce the porosity of the recycled fine aggregate, thereby improving the compactness of the recycled fine aggregate; the polyether polyol and the coupling agent can form a fine aggregate interface-coupling agent-polyether polyol-coupling agent-aggregate interface bridging structure in pores and microcracks of the recycled fine aggregate, and play a role in filling the pores of the recycled fine aggregate, bonding the cracks of the recycled aggregate, toughening and reinforcing and inhibiting crack expansion, so that the problems of low aggregate strength, high porosity, large water absorption and poor impermeability caused by the existence of microcracks after stress of the aggregate in the process of recycling and crushing are solved, and the performance of the recycled fine aggregate is improved.
In addition, according to the technical scheme, the starch ether and the modified palygorskite are added into the dry-mixed ground mortar formula, so that the viscosity and the water-retaining property of the mortar can be improved, and the thixotropy of the mortar can be improved by the modified palygorskite. Wherein the palygorskite is a water-containing magnesium-rich silicate clay mineral with a fiber texture layer chain transition structure. The modified palygorskite is an intricate and crossed bundle-shaped aggregate formed by needle-shaped crystal fibers, and the bundle-shaped aggregate can wrap large particles such as sand and the like in mortar so as to prevent the sand from settling in the mortar. The addition of the redispersible rubber powder in the formula of the dry-mixed ground mortar can improve the breaking strength, the bonding strength and the wear resistance of the ground mortar and reduce the shrinkage rate of the mortar. Both the cement and the redispersible gelatine powder have the function of a binding material, the former forming a hydrated product by chemical reaction with the water used for mixing, the latter acting by film formation during drying. This complementary binding mechanism provides stability and safety to the overall system. The water reducing agent is added into the dry-mixed ground mortar formula, so that the mortar has higher fluidity and stability. Further, the addition of sodium gluconate can adjust the setting time.
In a preferred embodiment of the invention, the mass ratio of the polyether polyol, the sodium silicate and the water is 0.5-2: 3-5: 100.
In a preferred embodiment of the invention, the mass ratio of the coupling agent to the absolute ethyl alcohol is 0.2-1.5: 100.
In a preferred embodiment of the invention, the mass ratio of the ordinary portland cement, the modified recycled fine aggregate, the class II fly ash, the modified palygorskite, the redispersible latex powder, the starch ether, the water reducing agent and the sodium gluconate is 170-200: 700-900: 10-40: 1-3: 1-4: 0.01-0.04: 0.1-0.2: 0.05-0.2.
In a preferred embodiment of the present invention, the construction waste is one or more of construction waste concrete, waste masonry, crushed stone, crushed brick and tile, and waste mortar.
In a preferred embodiment of the invention, the polyether polyol is PEG or PPG, and the molecular weight is 200-5000.
In a preferred embodiment of the present invention, the coupling agent is one or more of mercaptopropyltrimethoxysilane, anilinomethyltrimethoxysilane, isopropyltris (dioctylpyrophosphate) titanate and 3- (methacryloyloxy) propyltrimethoxysilane.
In a preferred embodiment of the invention, the redispersible latex powder is one or more of polyethylene vinyl acetate, polyvinyl acetate-vinyl versatate, polystyrene-acrylate, and polyacrylate.
In a preferred embodiment of the present invention, the water reducing agent is one or more of lignin-based water reducing agent powder, naphthalene-based water reducing agent powder, and polycarboxylic acid water reducing agent powder.
In a preferred embodiment of the present invention, the modified palygorskite has a fineness of 400 to 1000 mesh.
Next, a dry-mixed floor mortar prepared using the recycled aggregate according to the second aspect of the present invention, which is prepared by the method according to the first aspect of the present invention, will be described.
As proved by a large amount of process research and exploration of production practice of the inventor, when the preparation process for preparing the dry-mixed ground mortar by using the recycled aggregate comprises the raw material components, the mass ratio and the process conditions, all indexes of the dry-mixed ground mortar prepared by the method in the first aspect of the invention meet the requirements in GB/T14684 plus 2011 construction sand, and partial performances of the dry-mixed ground mortar are even better than those of the dry-mixed ground mortar prepared by natural river sand. In engineering construction, the modified recycled fine aggregate is adopted to replace natural river sand, so that the consumption of the natural sand in the large-scale engineering construction in China at present can be greatly reduced, mineral resources and energy sources are saved, the ecological environment is protected, and the construction waste is utilized to change waste into valuable.
In order to explain technical contents, structural features, and objects and effects of the technical means in detail, the following detailed description is given with reference to specific embodiments. The following examples are carried out on the premise of the technical scheme of the invention, and detailed embodiments and specific operation processes are given, but the scope of the invention is not limited to the following examples.
The raw material components, reagents, equipment and the like used in the examples of the present invention are commercially available unless otherwise specified.
EXAMPLE 1 preparation of RDS-1 Dry-mix ground mortar
(1) Modified recycled fine aggregate
a. Repeatedly crushing, refining, cleaning and screening the building waste concrete to obtain the recycled fine aggregate with the particle size of 0.08-4.75 mm.
b. Weighing polyether polyol PEG400 and sodium silicate, uniformly mixing, adding water, fully stirring and dissolving to obtain a modified slurry solution, wherein the mass ratio of the PEG400 to the sodium silicate to the water is 0.5:4.5: 100.
c. And (3) uniformly spraying the modified slurry solution on the surface of the recycled fine aggregate under stirring, so that the surface of the recycled fine aggregate is soaked by the modified slurry solution, the modified slurry solution fully permeates into microcracks of the fine aggregate, and then standing and airing to obtain the pretreated fine aggregate.
d. Dissolving coupling agent mercaptopropyl trimethoxy silane in absolute ethyl alcohol to prepare a coupling agent alcoholic solution, wherein the mass ratio of the coupling agent to the absolute ethyl alcohol is 0.2: 100.
e. And (3) putting the pretreated fine aggregate into a high-speed mixer, pumping the coupling agent alcohol solution in a fine mist state under stirring, stirring for 25min, and after the absolute ethyl alcohol is completely volatilized, preparing the modified recycled fine aggregate MRFA-1.
(2) Preparation of Dry-Mixed floor mortar
170 parts of ordinary portland cement (P.O 42.5.5), 808 parts of modified recycled fine aggregate (MRFA-1), 20 parts of grade II fly ash, 1 part of modified palygorskite with 400-mesh fineness, 1 part of polyethylene vinyl acetate, 0.01 part of starch ether, 0.15 part of polycarboxylic acid water reducer powder and 0.2 part of sodium gluconate are weighed according to the parts by weight and mixed uniformly to prepare the recycled fine aggregate dry-mixed ground mortar RDS-1.
EXAMPLE 2 preparation of RDS-2 Dry-mix ground mortar
(1) Modified recycled fine aggregate
a. Repeatedly crushing, refining, cleaning and screening the waste masonry to obtain the recycled fine aggregate with the particle size of 0.08-4.75 mm.
b. Weighing polyether glycol PPG1000 and sodium silicate, uniformly mixing, adding water, fully stirring and dissolving to obtain a modified slurry solution, wherein the weight ratio of PPG1000 to sodium silicate to water is 1:3.5: 100.
c. And (3) uniformly spraying the modified slurry solution on the surface of the recycled fine aggregate under stirring, so that the surface of the recycled fine aggregate is soaked by the modified slurry solution, the modified slurry solution fully permeates into microcracks of the fine aggregate, and then standing and airing to obtain the pretreated fine aggregate.
d. Dissolving a coupling agent aniline methyl trimethoxy silane in absolute ethyl alcohol to prepare a coupling agent alcoholic solution, wherein the mass ratio of the coupling agent to the absolute ethyl alcohol is 0.5: 100.
e. And (3) putting the pretreated fine aggregate into a high-speed mixer, pumping the coupling agent alcohol solution in a fine mist state under stirring, stirring for 30min, and after the absolute ethyl alcohol is completely volatilized, preparing the modified recycled fine aggregate MRFA-2.
(2) Preparation of Dry-Mixed floor mortar
Weighing 180 parts of ordinary portland cement (P.O 42.5.5), 801 parts of modified recycled fine aggregate (MRFA-2), 15 parts of grade II fly ash, 2 parts of modified palygorskite with the fineness of 500 meshes, 2.5 parts of polyvinyl acetate-vinyl versatate, 0.02 part of starch ether, 0.10 part of naphthalene water reducer powder and 0.07 part of sodium gluconate according to the parts by weight, and uniformly mixing to prepare the recycled fine aggregate dry-mixed ground mortar RDS-2.
EXAMPLE 3 preparation of RDS-3 Dry-mix ground mortar
(1) Modified recycled fine aggregate
a. Repeatedly crushing, refining, cleaning and screening the waste mortar to obtain recycled fine aggregate with the particle size of 0.08-4.75 mm.
b. Weighing polyether glycol PPG4000 and sodium silicate, uniformly mixing, adding water, fully stirring and dissolving to obtain a modified slurry solution, wherein the weight ratio of PPG4000 to sodium silicate to water is 1.5:4: 100.
c. And (3) uniformly spraying the modified slurry solution on the surface of the recycled fine aggregate under stirring, so that the surface of the recycled fine aggregate is soaked by the modified slurry solution, the modified slurry solution fully permeates into microcracks of the fine aggregate, and then standing and airing to obtain the pretreated fine aggregate.
d. Dissolving coupling agent isopropyl tri (dioctyl pyrophosphato acyloxy) titanate in absolute ethyl alcohol to prepare coupling agent alcoholic solution, wherein the mass ratio of the coupling agent to the absolute ethyl alcohol is 1: 100.
e. And (3) putting the pretreated fine aggregate into a high-speed mixer, pumping the coupling agent alcohol solution in a fine mist state under stirring, stirring for 20min, and after the absolute ethyl alcohol is completely volatilized, preparing the modified recycled fine aggregate MRFA-3.
(2) Preparation of Dry-Mixed floor mortar
190 parts of ordinary portland cement (P.O 42.5.5), 794 parts of modified recycled fine aggregate (MRFA-3), 10 parts of grade II fly ash, 2.5 parts of modified palygorskite with the fineness of 700 meshes, 4 parts of polystyrene-acrylate, 0.03 part of starch ether, 0.15 part of polycarboxylic acid water reducer powder and 0.06 part of sodium gluconate are weighed according to the parts by weight and uniformly mixed to prepare the recycled fine aggregate dry-mixed ground mortar RDS-3.
EXAMPLE 4 preparation of RDS-4 Dry-mix floor mortar
(1) Modified recycled fine aggregate
a. Repeatedly crushing, refining, cleaning and screening the building waste concrete to obtain the recycled fine aggregate with the particle size of 0.08-4.75 mm.
b. Weighing polyether glycol PEG2000 and sodium silicate, uniformly mixing, adding water, fully stirring and dissolving to obtain a modified slurry solution, wherein the mass ratio of the PEG2000 to the sodium silicate to the water is 2:3: 100.
c. And (3) uniformly spraying the modified slurry solution on the surface of the recycled fine aggregate under stirring, so that the surface of the recycled fine aggregate is soaked by the modified slurry solution, the modified slurry solution fully permeates into microcracks of the fine aggregate, and then standing and airing to obtain the pretreated fine aggregate.
d. Dissolving a coupling agent 3- (methacryloyloxy) propyl trimethoxy silane in absolute ethyl alcohol to prepare a coupling agent alcohol solution, wherein the mass ratio of the coupling agent to the absolute ethyl alcohol is 1.5: 100.
e. And (3) putting the pretreated fine aggregate into a high-speed mixer, pumping the coupling agent alcohol solution in a fine mist state under stirring, stirring for 10min, and after the absolute ethyl alcohol is completely volatilized, preparing the modified recycled fine aggregate MRFA-4.
(2) Preparation of Dry-Mixed floor mortar
Weighing 175 parts of ordinary portland cement (P.O 42.5.5), 779 parts of modified recycled fine aggregate (MRFA-4), 40 parts of class II fly ash, 3 parts of modified palygorskite with the fineness of 1000 meshes, 3 parts of polyacrylate, 0.04 part of starch ether, 0.20 part of lignin water reducer powder and 0.10 part of sodium gluconate according to the parts by weight, and uniformly mixing to prepare the recycled fine aggregate dry-mixed ground mortar RDS-4.
Comparative examples 1 to 4
The modified recycled fine aggregate MRFA-1 to MRFA-4 of the dry-mixed floor mortar of examples 1 to 4 was replaced with natural river sand to prepare corresponding comparative examples NDS-1 to NDS-4.
Comparative examples 5 to 8
The recycled fine aggregates which were not modified in examples 1 to 4 were designated as recycled fine aggregates 1 to 4, and the recycled fine aggregates 1 to 4 were prepared into dry-mixed floor mortars UDS-1 to UDS-4, respectively.
The modified recycled fine aggregates MRFA-1 to MRFA-4 in examples 1 to 4, the natural river sand in comparative examples 1 to 4 and the recycled fine aggregates 1 to 4 which are not modified in comparative examples 5 to 8 are respectively detected according to the standard of GB/T14684- "construction sand", and the detection results are shown in Table 1.
TABLE 1 Fine aggregate Performance parameter comparison Table
The detection results in table 1 show that the water absorption and crushing value indexes of the recycled fine aggregate can be effectively reduced through modification treatment (activation and strengthening treatment), the compactness is improved, and the quality loss is reduced, so that the technical scheme of the invention effectively solves the problems of low strength, high porosity, large water absorption and poor impermeability of the aggregate caused by microcracks existing after the aggregate is stressed in the recycling and crushing process, and greatly improves the performance of the recycled fine aggregate. In addition, all performance parameters of the modified recycled fine aggregate meet the standard requirements, are equivalent to or even slightly better than natural river sand, and indicate that the modified recycled fine aggregate can replace the natural river sand to be applied to preparation of dry-mixed ground mortar.
The dry-mixed floor mortars (RDS-1, RDS-2, RDS-3 and RDS-4) prepared in examples 1-4, the dry-mixed floor mortars (NDS-1, NDS-2, NDS-3 and NDS-4) prepared in comparative examples 1-4, and the dry-mixed floor mortars (UDS-1, UDS-2, UDS-3 and UDS-4) prepared in comparative examples 5-8 were subjected to performance tests according to the standard of GB/T25181-:
TABLE 2 comparison table of dry-mixed ground mortar performance
From the test results in Table 2, it can be seen that the 28d compressive strength of the dry-mixed ground mortars RDS-1 to RDS-4 prepared by using the modified recycled fine aggregate in examples 1 to 4 is improved by about 20%, the water retention rate is improved by about 17%, the setting time is improved by about 9%, and the consistency loss rate in 2 hours is reduced by about 32% as compared with the dry-mixed ground mortars UDS-1 to UDS-4 prepared by using the unmodified recycled fine aggregates 1 to 4 in comparative examples 5 to 8. In addition, compared with the dry-mixed ground mortar NDS-1 to NDS-4 prepared by adopting the natural river sand in the comparative examples 1 to 4, the dry-mixed ground mortar RDS-1 to RDS-4 prepared by adopting the modified recycled fine aggregate in the examples 1 to 4 has equivalent performance in the aspects of water retention rate, setting time, 2h consistency loss rate and the like, and the difference is not large; in the aspect of 28d compressive strength, RDS-1 to RDS-4 are superior to corresponding comparative examples NDS-1 to NDS-4, which shows that the modified recycled fine aggregate can completely replace natural river sand, and the performance of the dry-mixed ground mortar prepared by the modified recycled fine aggregate is slightly superior to that of the dry-mixed ground mortar prepared by the corresponding natural river sand.
The above description is of the preferred embodiment of the invention. It is to be understood that the invention is not limited to the particular embodiments described above, wherein technical parameters and raw material components which are not described in detail in the invention are changed within the range of the listed parameters, and the technical effects which are the same as or similar to the above-mentioned examples can be obtained, and still belong to the protection scope of the invention.
Finally, it is to be understood that those skilled in the art, on the basis of the method and technical disclosure disclosed above, may make numerous changes and modifications to the technical disclosure of the present invention, or may modify equivalent embodiments to equivalent variations, without departing from the scope of the technical disclosure of the present invention. Therefore, any simple modification, equivalent change and modification of the above embodiments, or the application of the above technical solutions to other related technical fields directly or indirectly by using the equivalent technical parameters, equivalent raw material components or equivalent process flow transformation performed in the present specification without departing from the technical solution of the present invention, shall still fall within the protection scope of the technical solution of the present invention.
Claims (10)
1. A method for preparing dry-mixed ground mortar by utilizing recycled aggregate is characterized by comprising the following steps:
(1) preparing modified recycled fine aggregate:
a. repeatedly crushing, refining, cleaning and screening the construction waste to obtain recycled fine aggregate with the particle size of 0.08-4.75 mm;
b. weighing polyether polyol and sodium silicate according to the weight parts, uniformly mixing, adding water, fully stirring and dissolving to obtain a modified slurry solution;
c. uniformly spraying the modified slurry solution on the surface of the recycled fine aggregate under stirring, so that the surface of the recycled fine aggregate is soaked by the modified slurry solution, the modified slurry solution fully permeates into microcracks of the recycled fine aggregate, and then standing and airing to obtain pretreated fine aggregate;
d. dissolving a coupling agent in absolute ethyl alcohol to prepare a coupling agent alcohol solution;
e. placing the pretreated fine aggregate into a high-speed mixer, pumping a coupling agent alcohol solution in a fine mist shape under stirring, stirring for 10-30 min, and preparing the modified recycled fine aggregate after absolute ethyl alcohol is completely volatilized;
(2) preparing dry-mixed ground mortar:
weighing and uniformly mixing ordinary portland cement, modified recycled fine aggregate, class II fly ash, modified palygorskite, redispersible latex powder, starch ether, water reducing agent and sodium gluconate according to the weight parts to obtain the dry-mixed ground mortar.
2. The method for preparing the dry-mixed ground mortar by using the recycled aggregate according to claim 1, wherein the mass ratio of the polyether polyol to the sodium silicate to the water is 0.5-2: 3-5: 100.
3. The method for preparing the dry-mixed ground mortar by using the recycled aggregate according to claim 1, wherein the mass ratio of the coupling agent to the absolute ethyl alcohol is 0.2-1.5: 100.
4. The method for preparing the dry-mixed ground mortar by using the recycled aggregate according to claim 1, wherein the mass ratio of the ordinary portland cement, the modified recycled fine aggregate, the class II fly ash, the modified palygorskite, the redispersible latex powder, the starch ether, the water reducing agent and the sodium gluconate is 170-200: 700-900: 10-40: 1-3: 1-4: 0.01-0.04: 0.1-0.2: 0.05-0.2.
5. The method for preparing dry-mixed floor mortar using recycled aggregate according to claim 1, wherein the construction waste is one or more of construction waste concrete, waste masonry, crushed stone, broken brick and tile, and waste mortar.
6. The method for preparing the dry-mixed ground mortar by using the recycled aggregate according to claim 1, wherein the polyether polyol is PEG or PPG, and the molecular weight range is 200-5000.
7. The method for preparing a dry-mixed floor mortar using recycled aggregate according to claim 1, wherein the coupling agent is one or more of mercaptopropyltrimethoxysilane, anilinomethyltrimethoxysilane, isopropyltris (dioctylpyroxyphosphate) titanate and 3- (methacryloyloxy) propyltrimethoxysilane.
8. The method for preparing dry-mixed ground mortar using recycled aggregate according to claim 1, wherein the re-dispersible latex powder is one or more of polyethylene vinyl acetate, polyethylene vinyl acetate-versatate, polystyrene-acrylate, polyacrylate;
the water reducing agent is one or more of lignin water reducing agent powder, naphthalene water reducing agent powder and polycarboxylic acid water reducing agent powder.
9. The method for preparing dry-mixed ground mortar by using recycled aggregate according to claim 1, wherein the fineness of the modified palygorskite is 400-1000 meshes.
10. A dry-mixed floor mortar prepared using recycled aggregate, characterized in that it is prepared by the method of any one of claims 1 to 9.
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