CN114790099A - Dry-mixed mortar and preparation method thereof - Google Patents
Dry-mixed mortar and preparation method thereof Download PDFInfo
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- CN114790099A CN114790099A CN202210388522.8A CN202210388522A CN114790099A CN 114790099 A CN114790099 A CN 114790099A CN 202210388522 A CN202210388522 A CN 202210388522A CN 114790099 A CN114790099 A CN 114790099A
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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
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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
- C04B2111/20—Resistance against chemical, physical or biological attack
- C04B2111/2038—Resistance against physical degradation
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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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- 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
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- Ceramic Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
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- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The application relates to the field of dry powder mortar, and particularly discloses dry powder mortar and a preparation method thereof. The dry powder mortar comprises the following substances in parts by weight: 130-150 parts of coated recycled coarse aggregate, 35-50 parts of cement, 50-60 parts of sand, 30-40 parts of fly ash, 25-30 parts of steel slag, 10-15 parts of silica fume and 5-10 parts of functional auxiliary agent; the coated recycled coarse aggregate is a recycled coarse aggregate coated and modified by polymer emulsion. The preparation method comprises the following steps: s1, treating recycled aggregate; s2, premixing; and S3, mixing twice. According to the application, the polymer emulsion is selected to coat the recycled aggregate, so that the toughness strength and the structural performance of the recycled aggregate are improved, and the structural performance of the dry-mixed mortar is improved.
Description
Technical Field
The application relates to the field of dry powder mortar, in particular to dry powder mortar and a preparation method thereof.
Background
The traditional mortar has the defects of various raw materials, the quality of mixing personnel, insufficient equipment metering and weather and other environmental factors, so that the uncertainty of the performance of the traditional field mixing mortar is too much, and the problems of uneven mixing, inaccurate proportioning, unqualified raw materials and the like exist, and the potential safety hazard exists in the use of the mortar. The dry powder mortar is also called dry mixed mortar or dry mortar powder and dry mortar mixture, different admixtures and various admixtures are added according to different varieties, the dry powder mortar is mixed with aggregate and a cementing material according to a certain proportion, a finished product mortar with stable performance is obtained through a drying process, and then the finished product mortar is uniformly bagged to be directly used by construction workers at the construction engineering location.
Compared with the traditional mortar prepared on site, the dry powder mortar has the following advantages: (1) firstly, the product quality is high. (2) Secondly, the production efficiency is high. (3) Moreover, the method is favorable for protecting the environment and ensuring the civilized construction. However, the cement concrete material prepared by the method is accompanied by various types of shrinkage under a series of reasons such as external temperature and humidity change, deformation of the cementing material, structural constraint and the like, and when the stress generated by shrinkage is greater than the tensile strength of the concrete material, the concrete material is cracked, so that the strength and impermeability of the concrete material are reduced. Generally, the main body part in the building structure can effectively improve the tensile strength of a concrete material through reinforcing bars, and the risk of cracking of the concrete is reduced.
In view of the above-mentioned related technologies, the inventors of the present invention have considered that the conventional dry mortar has insufficient resistance to shrinkage of concrete, and is liable to crack due to insufficient toughness and tensile strength of the dry mortar during the use of concrete.
Disclosure of Invention
In order to improve the defects of poor tensile strength and toughness of dry-mixed mortar, the application provides the dry-mixed mortar and a preparation method thereof.
The application provides dry-mixed mortar and a preparation method thereof, which adopt the following technical scheme:
in a first aspect, the present application provides a dry-mixed mortar, comprising the following substances in parts by weight:
coating 130-150 parts of recycled coarse aggregate;
35-50 parts of cement;
50-60 parts of sand;
30-40 parts of fly ash;
25-30 parts of steel slag;
10-15 parts of silica fume;
5-10 parts of a functional assistant;
the coated recycled coarse aggregate is a recycled coarse aggregate coated and modified by polymer emulsion.
By adopting the technical scheme, the polymer emulsion is selected for coating the recycled aggregate, on one hand, the polymer emulsion can form a coating on the surface of the recycled aggregate and permeate the inside of the pores of the recycled aggregate to form a coating film with a permeable structure. The coating film structure improves the toughness strength and the structural performance of the recycled aggregate and improves the structural performance of the dry powder mortar.
On the other hand, the recycled aggregate is coated by the polymer emulsion, calcium ions in a cement slurry pore solution are effectively chelated by the coating structure formed on the surface of the recycled coarse aggregate by the polymer emulsion, and silicate and precipitate generated by hydration reaction are delayed in the subsequent water adding using process, so that the defects of poor tensile strength and toughness of the dry powder mortar are effectively overcome.
Preferably, the dry powder mortar also comprises 20-30 parts by weight of anti-cracking modified material; the anti-cracking modified material comprises rubber powder and chopped rubber fibers which are mixed according to the mass ratio of 1: 5-8.
By adopting the technical scheme, the components of the dry powder mortar are further optimized, and an entanglement structure formed by compounding the rubber powder and the chopped rubber fibers is used as a main form of the main anti-cracking modified material. The twisted anti-crack modified material has high toughness and can effectively absorb partial stress in the mortar caused by external load, so that the deformation performance of the mortar can be greatly improved.
On this basis, the rubber powder that this application chose for use can effectively permeate the microporous structure hole in the mortar, and at the actual dry run of mortar, reduce base member dehydrated area, make moisture migration route extension, the fibre to the distribution in disorder simultaneously blocks the intercommunication of the capillary hole in the concrete, has reduced the capillary tension that the capillary dehydrated shrinkage formed, reduces the phenomenon of the shrinkage of base member to a certain extent to dry powder mortar tensile strength and toughness performance have been improved.
Preferably, the rubber powder and the chopped rubber fibers are both prepared from composite natural rubber prepared by modifying inorganic filler.
By adopting the technical scheme, the rubber powder and chopped rubber fiber components are further optimized, the inorganic filler is used for modifying the composite natural rubber material, and the filler/rubber network structure formed by the inorganic filler and the rubber material can bear larger external stress, so that the prepared rubber product has excellent abrasion resistance, and the abrasion resistance and the toughness strength of the rubber powder and chopped rubber fiber can be effectively improved.
Preferably, the composite natural rubber comprises the following substances in parts by weight:
55-80 parts of natural rubber particles;
0.1-1.0 part of tetraethylammonium bromide;
1-3 parts of heavy calcium powder;
6-8 parts of silica sol;
1-5 parts of carbon black.
By adopting the technical scheme, the composite natural rubber is further optimized, the heavy calcium powder is selected as the main modified material, the tetraethylammonium bromide is combined as the modified material, the network density of the filling rubber material is improved, and the hardness and the tensile strength of the rubber material are improved. Because the hydrophilic end of the tetraethyl ammonium bromide reacts with the heavy calcium powder to form a chemical bond, and the lipophilic functional group is connected with the sizing material matrix, the filler is tightly fit with the rubber matrix in this way and is not easy to fall off, so that the mechanical property of the natural sizing material prepared from the heavy calcium powder treated by the tetraethyl ammonium bromide is more excellent.
Preferably, the polymer emulsion is a stable styrene-acrylic emulsion prepared by doping and modifying silica sol, and the doping amount of the silica sol is 13-18% of the mass of the styrene-acrylic emulsion.
By adopting the technical scheme, the styrene-acrylic emulsion is further doped with silica sol, and as the nano silica particles in the silica sol are connected with styrene-acrylic emulsion molecules, and the coating is cured into a film, a relatively complete space network continuous structure is formed, the surface hardness of the recycled coarse aggregate is enhanced, and simultaneously the rigidity of the nano silica particles in the silica sol is fully exerted, so that the wear resistance of the coating is enhanced.
Preferably, the polymer emulsion further comprises aerogel particles, and the particle size of the aerogel particles is 30-80 μm.
By adopting the technical scheme, aerogel particles are further added into the polymer emulsion, and can be effectively dispersed in the polymer emulsion, so that in the subsequent process of coating the regenerated coarse aggregate, the aerogel particles can form a loose through hole structure in the formed polymer emulsion coating, and a regular scaly cavity structure is formed by the filler borne by the polymer emulsion coating, so that the specific surface area and the roughness of the regenerated coarse aggregate are effectively improved, and the bonding strength among all components of the dry powder mortar is further improved.
Preferably, the functional assistant comprises the following substances in parts by weight:
15-20 parts of a composite activator;
3-5 parts of polyvinyl alcohol;
0.1-2.5 parts of sodium carbonate;
30-40 parts of a water reducing agent; the compound excitant comprises a mixture of an alkaline excitant and a sulfate excitant.
By adopting the technical scheme, alkali substances in the alkaline activator in the composite activator selected by the application can improve the liquid-phase alkalinity of the slurry, and the improvement of the liquid-phase alkalinity can promote the breakage of Si-O and Al-O bonds on the surface of the recycled aggregate on the one hand, so that the polymerization degree of the network polymer of silicon oxide and aluminum oxide on the surface of the recycled aggregate is reduced, the free unsaturated active bonds on the surface of the recycled aggregate are increased, and the reaction of the free unsaturated active bonds with calcium hydroxide and other components in the liquid phase of the system is easier.
The sulfate in the composite exciting agent can rapidly react with the activated alumina in the recycled aggregate and the calcium aluminate in the cement to produce ettringite, and the volume of the ettringite expands, so that microcracks in the recycled aggregate are further blocked, and gaps at the interface of the recycled aggregate and the cement matrix are filled. Thereby further improving the toughness strength and the mechanical property of the dry powder mortar.
In a second aspect, the application also provides a preparation method of the dry-mixed mortar, which comprises the following preparation steps:
s1, recycled aggregate treatment: taking the regenerated coarse aggregate, washing pumice on the surface of the regenerated coarse aggregate, soaking the regenerated coarse aggregate in polymer emulsion, pressurizing, drying in vacuum, and collecting to obtain coated regenerated coarse aggregate;
s2, premixing: firstly, taking the coated recycled coarse aggregate, cement, sand, pulverized coal, steel slag and silica fume, stirring and mixing, and collecting to obtain a premix;
s3, secondary mixing: taking the premix and the functional additive, and stirring and mixing to obtain the dry-mixed mortar.
By adopting the technical scheme, the recycled aggregate is firstly coated, and the structure of the material which is most likely to cause the deterioration phenomenon in the dry powder mortar material is improved by modifying the recycled aggregate, so that the dry powder mortar material has good structural performance, and the toughness strength and the mechanical property of the dry powder mortar are effectively improved by adopting the scheme of premixing and secondary mixing.
In summary, the present application has the following beneficial effects:
first, this application selects polymer emulsion to carry out the cladding to the regeneration aggregate, and on the one hand, polymer emulsion can form the cladding on regeneration aggregate surface and permeate to the inside coating film that thereby forms the infiltration structure of the hole of regeneration aggregate. The coating film structure improves the toughness strength and the structural performance of the recycled aggregate and improves the structural performance of the dry powder mortar.
On the other hand, the recycled aggregate is coated by the polymer emulsion, calcium ions in a pore solution of the cement slurry are effectively chelated by a coating structure formed on the surface of the recycled coarse aggregate by the polymer emulsion, and silicate and precipitate generated by hydration reaction are delayed in the subsequent water adding use process, so that the defects of poor tensile strength and toughness of the dry powder mortar are effectively overcome.
Secondly, the components of the dry powder mortar are further optimized, and an entanglement structure formed by compounding rubber powder and chopped rubber fibers is selected as a main form of the main anti-cracking modified material. The twisted anti-crack modified material has high toughness and can effectively absorb partial stress in the mortar caused by external load, so that the deformation performance of the mortar can be greatly improved.
On this basis, the rubber powder that this application chose for use can effectively permeate the microporous structure hole in the mortar, and at the actual dry run of mortar, reduce base member dehydrated area, make moisture migration route extension, the fibre to the distribution in disorder simultaneously blocks the intercommunication of the capillary hole in the concrete, has reduced the capillary tension that the capillary dehydrated shrinkage formed, reduces the phenomenon of the shrinkage of base member to a certain extent to dry powder mortar tensile strength and toughness performance have been improved.
And thirdly, the styrene-acrylic emulsion is further doped with silica sol, and as the nano silica particles in the silica sol are connected with styrene-acrylic emulsion molecules, a relatively complete space network continuous structure is formed after the coating is cured into a film, the surface hardness of the regenerated coarse aggregate is enhanced, and simultaneously the rigidity of the nano silica particles in the silica sol is fully exerted, so that the wear resistance of the coating is enhanced.
Detailed Description
The present application will be described in further detail with reference to examples.
In the embodiment of the present application, the selected devices are as follows, but not limited to:
styrene-acrylic emulsion: VAE707, chen chemical limited of denan;
styrene-butadiene emulsion: jinan Yucai chemical Co., Ltd., solid content 48.
Preparation examples
Preparation example 1
Taking 55kg of natural rubber particles, 0.1kg of tetraethylammonium bromide, 1kg of heavy calcium powder, 6kg of silica sol with the solid content of 15 percent and 1kg of carbon black, stirring, mixing, open milling and collecting the composite natural rubber 1.
Preparation example 2
Taking 72kg of natural rubber particles, 0.7kg of tetraethylammonium bromide, 2kg of heavy calcium powder, 7kg of silica sol with the solid content of 15 percent and 2kg of carbon black, stirring, mixing, open milling, and collecting the composite natural rubber 2.
Preparation example 3
80kg of natural rubber particles, 1.0kg of tetraethylammonium bromide, 3kg of heavy calcium powder, 8kg of silica sol with the solid content of 15 percent and 5kg of carbon black are taken, stirred, mixed and milled, and the composite natural rubber 3 is obtained.
Preparation example 4
1, cracking-resistant modified material: 1kg of the rubber powder prepared in preparation example 1 with the particle size of 1-50 μm and 5kg of the chopped rubber fiber prepared in preparation example 1 with the length of 1mm are stirred and mixed, and the anti-cracking modified material 1 is collected.
Preparation example 5
Anti-cracking modified material 2: 1kg of the rubber powder prepared in preparation example 1 with the diameter of 1-50 μm and 6.5kg of the chopped rubber fiber prepared in preparation example 1 with the length of 1mm are stirred and mixed, and the anti-cracking modified material 2 is collected.
Preparation example 6
Anti-cracking modified material 3: 1kg of rubber powder prepared in preparation example 1 and 1-50 μm in diameter and 8kg of chopped rubber fibers prepared in preparation example 1 and having a length of 1mm are stirred and mixed, and the anti-cracking modified material 3 is collected.
Preparation example 7
Anti-cracking modified material 4: in contrast to preparation example 4, the rubber powder prepared in preparation example 2 and the chopped rubber fibers prepared in preparation example 2 were used in place of the rubber powder and the chopped rubber fibers in preparation example 4.
Preparation example 8
Anti-cracking modified material 5: in contrast to preparation example 4, the rubber powder prepared in preparation example 3 and the chopped rubber fibers prepared in preparation example 3 were used in place of the rubber powder and the chopped rubber fibers in preparation example 4.
Preparation example 9
Styrene-acrylic emulsion 1: 1kg of silica sol with the solid content of 15 percent is added into the styrene-acrylic emulsion, and the adding amount of the silica sol is controlled to be 13 percent of the styrene-acrylic emulsion.
Preparation example 10
Styrene-acrylic emulsion 2: 1kg of silica sol with the solid content of 15 percent is added into the styrene-acrylic emulsion, and the adding amount of the silica sol is controlled to be 15 percent of the styrene-acrylic emulsion.
Preparation example 11
Styrene-acrylic emulsion 3: 1kg of silica sol with the solid content of 15 percent is added into the styrene-acrylic emulsion, and the adding amount of the silica sol is controlled to be 18 percent of the styrene-acrylic emulsion.
Preparation example 12
Compared with the preparation example 9, the styrene-acrylic emulsion 4 is also added with 0.05kg of aerogel particles with the particle size of 30-80 microns.
Preparation example 13
Functional auxiliary agent 1: stirring and mixing 20kg of sodium bicarbonate and 20kg of sodium sulfate, and collecting to obtain a compound excitant; and then taking 15kg of composite exciting agent, 3kg of polyvinyl alcohol, 0.1kg of sodium carbonate and 30kg of naphthalene water reducing agent, stirring and mixing to prepare the functional additive 1.
Preparation example 14
Functional auxiliary agent 2: stirring and mixing 20kg of sodium bicarbonate and 20kg of sodium sulfate, and collecting to obtain a compound excitant; and then taking 17kg of composite exciting agent, 4kg of polyvinyl alcohol, 1.2kg of sodium carbonate and 35kg of naphthalene water reducing agent, stirring and mixing to prepare the functional auxiliary agent 2.
Preparation example 15
Functional auxiliary agent 3: stirring and mixing 20kg of sodium bicarbonate and 20kg of sodium sulfate, and collecting to obtain a compound excitant; and then 20kg of composite exciting agent, 5kg of polyvinyl alcohol, 2.5kg of sodium carbonate and 40kg of naphthalene water reducing agent are taken, stirred and mixed to prepare the functional additive 3.
Examples
Example 1
A dry powder mortar comprises 130kg of coated recycled coarse aggregate, 35kg of cement, 50kg of sand, 30kg of fly ash, 25kg of steel slag, 10kg of silica fume and 5kg of functional additive 1.
A preparation method of dry-mixed mortar comprises the following steps:
s1, recycled aggregate treatment: taking the regenerated coarse aggregate, washing pumice on the surface of the regenerated coarse aggregate, soaking the regenerated coarse aggregate in styrene-acrylic emulsion, pressurizing at 5MPa, drying at 45 ℃ in vacuum, and collecting the coated regenerated coarse aggregate;
s2, premixing: firstly, taking the coated recycled coarse aggregate, cement, sand, pulverized coal, steel slag and silica fume, stirring and mixing, and collecting to obtain a premix;
s3, secondary mixing: taking the premix and the functional additive, and stirring and mixing to prepare the dry powder mortar.
Example 2
The dry powder mortar comprises 140kg of coated recycled coarse aggregate, 42kg of cement, 55kg of sand, 35kg of fly ash, 27kg of steel slag, 12kg of silica fume and 7kg of functional additive 2.
A preparation method of dry-mixed mortar comprises the following steps:
s1, recycled aggregate treatment: taking the regenerated coarse aggregate, washing pumice on the surface of the regenerated coarse aggregate, soaking the regenerated coarse aggregate in styrene-acrylic emulsion, pressurizing at 5MPa, drying at 45 ℃ in vacuum, and collecting the coated regenerated coarse aggregate;
s2, premixing: firstly, taking the coated recycled coarse aggregate, cement, sand, pulverized coal, steel slag and silica fume, stirring and mixing, and collecting to obtain a premix;
s3, secondary mixing: taking the premix and the functional additive, and stirring and mixing to prepare the dry powder mortar.
Example 3
A dry powder mortar comprises 150kg of coated recycled coarse aggregate, 50kg of cement, 60kg of sand, 40kg of fly ash, 30kg of steel slag, 15kg of silica fume and 10kg of functional additive 3.
A preparation method of dry-mixed mortar comprises the following steps:
s1, recycled aggregate treatment: taking the regenerated coarse aggregate, washing pumice on the surface of the regenerated coarse aggregate, soaking the regenerated coarse aggregate in styrene-acrylic emulsion, pressurizing at 5MPa, drying at 45 ℃ in vacuum, and collecting the coated regenerated coarse aggregate;
s2, premixing: firstly, taking the coated recycled coarse aggregate, cement, sand, pulverized coal, steel slag and silica fume, stirring and mixing, and collecting to obtain a premix;
s3, secondary mixing: taking the premix and the functional additive, and stirring and mixing to obtain the dry-mixed mortar.
Example 4
The preparation method of the dry-mixed mortar is different from the preparation method of the embodiment 1 in that the styrene-acrylic emulsion 1 adopted in the embodiment 4 replaces the styrene-acrylic emulsion.
Example 5
The preparation method of the dry-mixed mortar is different from the preparation method of the embodiment 1 in that the styrene-acrylic emulsion 2 adopted in the embodiment 5 replaces the styrene-acrylic emulsion.
Example 6
The preparation method of the dry powder mortar is different from the embodiment 1 in that the styrene-acrylic emulsion 3 adopted in the embodiment 6 replaces the styrene-acrylic emulsion.
Example 7
The preparation method of the dry-mixed mortar is different from the preparation method of the embodiment 1 in that the styrene-acrylic emulsion 4 is adopted in the embodiment 7 to replace the styrene-acrylic emulsion.
Example 8
The preparation method of the dry-mixed mortar is different from the preparation method of the embodiment 1 in that the styrene-butadiene emulsion adopted in the embodiment 8 replaces the styrene-acrylic emulsion.
Example 9
Compared with the embodiment 1, the embodiment 9 also adds 20kg of the anti-crack modifier 1.
Example 10
Compared with the embodiment 1, the embodiment 10 also adds 25kg of the anti-crack modifier 1.
Example 11
In example 11, 30kg of an anti-cracking modifier 1 was added, as compared with example 1.
Example 12
Compared with the example 9, the dry powder mortar in the example 12 is added with 20kg of anti-cracking modifier 2.
Example 13
Compared with the embodiment 9, the embodiment 13 also adds 20kg of the anti-crack modifier 3.
Comparative example
Comparative example 1
A dry mortar, different from example 1, is obtained in comparative example 1 by using recycled coarse aggregate which has not been modified by coating with a polymer emulsion.
Performance test
The compressive strength test performance was performed on examples 1 to 12 and comparative example 1.
The test method comprises the following steps: and stirring and mixing water with the same mass as the cement and the dry powder mortar to obtain cement mortar.
And (3) formulating a maintenance scheme: according to JGJ/T70-2009 Standard of basic performance test methods of building mortar, after mortar is molded, placing the molded mortar in a curing box with the temperature of 20 +/-3 ℃ and the relative humidity of 95 +/-3 percent, keeping for 24 hours, then demolding, finishing the benchmark curing of the test piece, and then changing the relative humidity and time conditions of curing. And (3) maintaining the environment: after the standard curing is finished, the mixture is continuously cured in a curing box with the temperature of 20 +/-3 ℃ and the relative humidity of 95 +/-3 percent to the specified age (7, 14 and 28 d).
The compressive strength of the mortar was tested according to JGJ/T70-2009 and JG/T230-2007 premixed mortar.
TABLE 1 Performance test Table
By combining the performance test tables of examples 1-3, examples 4-7, example 8, examples 9-13 and comparative example 1 and table 1, the comparison can find that:
(1) firstly, comparing the performances of the examples 1 to 3 and the example 8 with the comparative example 1, as can be seen from the data in table 1, the tensile strength of the examples 1 to 3 is more excellent, and the technical scheme of the application is described by combining the schemes of the examples 1 to 3, the example 7 and the comparative example 1, wherein the polymer emulsion is selected to coat the recycled aggregate, and on one hand, the polymer emulsion can form a coating on the surface of the recycled aggregate and permeate the inside of the pores of the recycled aggregate to form a coating film structure. The coating film structure improves the toughness strength and the structural performance of the recycled aggregate and improves the structural performance of the dry powder mortar. On the other hand, the recycled aggregate is coated by the polymer emulsion, calcium ions in a pore solution of the cement topic are effectively chelated by a coating structure formed on the surface of the recycled coarse aggregate by the polymer emulsion, and silicate and precipitate generated by hydration reaction are delayed in subsequent water adding usage, so that the defects of poor tensile strength and toughness of the dry-mixed mortar are effectively overcome.
(2) Comparing examples 4-7 with example 1, the data of examples 4-7 is more excellent than that of example 1, which indicates that the technical scheme of the present application further dopes silica sol in the styrene-acrylic emulsion, and the nano silica particles in the silica sol are connected with styrene-acrylic emulsion molecules, so that after the coating is cured to form a film, a relatively complete spatial network continuous structure is formed, the surface hardness of the recycled coarse aggregate is enhanced, and the rigidity of the nano silica particles in the silica sol is fully exerted, so that the wear resistance of the coating is enhanced.
Compared with the embodiments 4-6 and 7, the technical scheme of the application is further explained by adding aerogel particles into the polymer emulsion, and the aerogel particles can be effectively dispersed in the polymer emulsion, so that in the subsequent process of coating the recycled coarse aggregate, the aerogel particles can form a loose through hole structure in the formed polymer emulsion coating, and a regular scale-shaped cavity structure is formed by the filler loaded by the polymer emulsion coating, so that the specific surface area and the roughness of the recycled coarse aggregate are effectively improved, and the bonding strength among the components of the dry powder mortar is further improved.
(3) Comparing examples 9-13 with example 1, the data of examples 9-13 is more excellent, and further illustrating that the technical scheme of the application further optimizes the components of the dry-mixed mortar, and the components of the dry-mixed mortar have higher toughness by selecting rubber powder and chopped rubber fibers as main anti-cracking modified materials, and can effectively absorb partial stress in the mortar caused by external load, thereby greatly improving the deformation performance of the mortar. On this basis, the rubber powder that this application chose for use can effectively permeate the microporous structure hole in the mortar, and at the actual dry run of mortar, make the base member area of losing water reduce, the extension of moisture migration route, and the fibre of distributing in disorder has also blocked the intercommunication of the capillary hole in the concrete simultaneously, has reduced the capillary tension that the capillary shrinkage formed to can reduce the shrinkage phenomenon of base member to a certain extent, thereby has improved dry powder mortar tensile strength and toughness.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.
Claims (8)
1. The dry powder mortar is characterized by comprising the following substances in parts by weight:
coating 130-150 parts of recycled coarse aggregate;
35-50 parts of cement;
50-60 parts of sand;
30-40 parts of fly ash;
25-30 parts of steel slag;
10-15 parts of silica fume;
5-10 parts of a functional assistant;
the coated recycled coarse aggregate is a recycled coarse aggregate modified by coating of a polymer emulsion.
2. The dry powder mortar according to claim 1, further comprising 20-30 parts by weight of an anti-crack modifying material; the anti-cracking modified material comprises rubber powder and chopped rubber fibers which are mixed according to the mass ratio of 1: 5-8.
3. The dry-mixed mortar as claimed in claim 2, wherein the rubber powder and the chopped rubber fiber are both prepared from composite natural rubber prepared by modifying inorganic filler.
4. The dry powder mortar according to claim 2, wherein the composite natural rubber comprises the following components in parts by weight:
55-80 parts of natural rubber particles;
0.1-1.0 part of tetraethyl ammonium bromide;
1-3 parts of heavy calcium powder;
6-8 parts of silica sol;
1-5 parts of carbon black.
5. The dry powder mortar according to claim 1, wherein the polymer emulsion is a stable styrene-acrylic emulsion prepared by doping and modifying silica sol, and the doping amount of the silica sol is 13-18% of the mass of the styrene-acrylic emulsion.
6. The dry powder mortar according to claim 1, wherein the polymer emulsion further comprises aerogel particles, and the particle size of the aerogel particles is 30-80 μm.
7. The dry powder mortar according to claim 1, wherein the functional additive comprises the following substances in parts by weight:
15-20 parts of a composite activator;
3-5 parts of polyvinyl alcohol;
0.1-2.5 parts of sodium carbonate;
30-40 parts of a water reducing agent; the compound activator comprises a mixture of an alkaline activator and a sulfate activator.
8. The preparation method of the dry-mixed mortar according to any one of claims 1 to 7, characterized by comprising the following preparation steps:
s1, recycled aggregate treatment: taking the recycled coarse aggregate, washing pumice on the surface of the recycled coarse aggregate, soaking the recycled coarse aggregate in polymer emulsion, pressurizing, drying in vacuum, and collecting the coated recycled coarse aggregate;
s2, premixing: firstly, taking the coated recycled coarse aggregate, cement, sand, pulverized coal, steel slag and silica fume, stirring and mixing, and collecting to obtain a premix;
s3, secondary mixing: taking the premix and the functional additive, and stirring and mixing to prepare the dry powder mortar.
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| CN202210388522.8A CN114790099B (en) | 2022-04-14 | 2022-04-14 | Dry-mixed mortar and preparation method thereof |
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| CN202210388522.8A CN114790099B (en) | 2022-04-14 | 2022-04-14 | Dry-mixed mortar and preparation method thereof |
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| CN115353354A (en) * | 2022-09-16 | 2022-11-18 | 广东筠诚建筑科技有限公司 | Novel concrete prepared from stone processing waste and preparation method thereof |
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