CN114988737A - Composite material for improving crack resistance of concrete and preparation method and application thereof - Google Patents
Composite material for improving crack resistance of concrete and preparation method and application thereof Download PDFInfo
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- CN114988737A CN114988737A CN202210625846.9A CN202210625846A CN114988737A CN 114988737 A CN114988737 A CN 114988737A CN 202210625846 A CN202210625846 A CN 202210625846A CN 114988737 A CN114988737 A CN 114988737A
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- 239000004567 concrete Substances 0.000 title claims abstract description 104
- 239000002131 composite material Substances 0.000 title claims abstract description 32
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims abstract description 154
- 229910000019 calcium carbonate Inorganic materials 0.000 claims abstract description 77
- 239000013078 crystal Substances 0.000 claims abstract description 60
- 239000000843 powder Substances 0.000 claims abstract description 55
- 239000004575 stone Substances 0.000 claims abstract description 46
- 239000000463 material Substances 0.000 claims abstract description 32
- 239000004568 cement Substances 0.000 claims abstract description 25
- 238000002156 mixing Methods 0.000 claims abstract description 14
- 238000006243 chemical reaction Methods 0.000 claims description 19
- 239000003792 electrolyte Substances 0.000 claims description 19
- 238000000227 grinding Methods 0.000 claims description 18
- 239000000047 product Substances 0.000 claims description 18
- 238000001035 drying Methods 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- 239000011575 calcium Substances 0.000 claims description 13
- 229910052791 calcium Inorganic materials 0.000 claims description 13
- 239000000706 filtrate Substances 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 13
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 12
- 239000002244 precipitate Substances 0.000 claims description 11
- 238000004140 cleaning Methods 0.000 claims description 10
- 239000002994 raw material Substances 0.000 claims description 10
- 238000001914 filtration Methods 0.000 claims description 9
- 238000012216 screening Methods 0.000 claims description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 6
- 238000005868 electrolysis reaction Methods 0.000 claims description 6
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 5
- 238000005273 aeration Methods 0.000 claims description 5
- 239000011777 magnesium Substances 0.000 claims description 5
- 229910052749 magnesium Inorganic materials 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- 238000005336 cracking Methods 0.000 abstract description 15
- 239000000835 fiber Substances 0.000 abstract description 4
- 239000000126 substance Substances 0.000 abstract description 4
- 238000002425 crystallisation Methods 0.000 abstract 1
- 230000008025 crystallization Effects 0.000 abstract 1
- 230000006698 induction Effects 0.000 abstract 1
- 238000005457 optimization Methods 0.000 abstract 1
- 230000008092 positive effect Effects 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 20
- 230000000694 effects Effects 0.000 description 12
- 238000006703 hydration reaction Methods 0.000 description 12
- 230000036571 hydration Effects 0.000 description 10
- 239000007788 liquid Substances 0.000 description 10
- 239000000203 mixture Substances 0.000 description 9
- 239000011148 porous material Substances 0.000 description 9
- 239000012153 distilled water Substances 0.000 description 7
- 239000000243 solution Substances 0.000 description 7
- 238000003756 stirring Methods 0.000 description 7
- 235000013312 flour Nutrition 0.000 description 6
- 239000002245 particle Substances 0.000 description 5
- 238000005303 weighing Methods 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 230000001276 controlling effect Effects 0.000 description 4
- 239000010439 graphite Substances 0.000 description 4
- 229910002804 graphite Inorganic materials 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 3
- 235000019738 Limestone Nutrition 0.000 description 3
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 3
- 229910001424 calcium ion Inorganic materials 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 238000011049 filling Methods 0.000 description 3
- 239000006028 limestone Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000011259 mixed solution Substances 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 230000001502 supplementing effect Effects 0.000 description 3
- HMUNWXXNJPVALC-UHFFFAOYSA-N 1-[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]-2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethanone Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)C(CN1CC2=C(CC1)NN=N2)=O HMUNWXXNJPVALC-UHFFFAOYSA-N 0.000 description 2
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 2
- 229920001410 Microfiber Polymers 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000007385 chemical modification Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
- 229910001653 ettringite Inorganic materials 0.000 description 2
- 238000009472 formulation Methods 0.000 description 2
- 230000001965 increasing effect Effects 0.000 description 2
- 239000003112 inhibitor Substances 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000003658 microfiber Substances 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- LDXJRKWFNNFDSA-UHFFFAOYSA-N 2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]ethanone Chemical compound C1CN(CC2=NNN=C21)CC(=O)N3CCN(CC3)C4=CN=C(N=C4)NCC5=CC(=CC=C5)OC(F)(F)F LDXJRKWFNNFDSA-UHFFFAOYSA-N 0.000 description 1
- YLZOPXRUQYQQID-UHFFFAOYSA-N 3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]propan-1-one Chemical compound N1N=NC=2CN(CCC=21)CCC(=O)N1CCN(CC1)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F YLZOPXRUQYQQID-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- ZFXVRMSLJDYJCH-UHFFFAOYSA-N calcium magnesium Chemical compound [Mg].[Ca] ZFXVRMSLJDYJCH-UHFFFAOYSA-N 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000002657 fibrous material Substances 0.000 description 1
- 239000010438 granite Substances 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910001629 magnesium chloride Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000009423 ventilation Methods 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
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/50—Processes
-
- 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)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Metallurgy (AREA)
- Ceramic Engineering (AREA)
- Structural Engineering (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The invention discloses a composite material for improving the crack resistance of concrete and a preparation method thereof, wherein the composite material is prepared by mixing and homogenizing 60-70% of calcium carbonate crystal seeds and 30-40% of calcium carbonate crystal whiskers in powder mixing equipment at a rotating speed of 20-60 r/min. The stone powder is subjected to chemical crystallization induction and physical granularity optimization, is designed into a composite functional material with a fiber structure and an ultrafine structure, and is reasonably mixed according to the technical requirements of different types of concrete, so that the positive effect of the invention in the cement concrete is fully exerted, and the full-life anti-cracking performance of the concrete is improved from a plasticity stage and a hardening service stage.
Description
Technical Field
The invention belongs to the technical field of concrete construction, and particularly relates to a composite material for improving the crack resistance of concrete, and a preparation method and application thereof.
Background
At present, as is well known to those skilled in the art, concrete cracks are a technical requirement which is not favorable for the high durability of modern concrete, the cracks provide passages for external erosion media to enter the interior of the concrete, harmful substances induce various erosion effects in the interior of the concrete, steel bar corrosion and concrete quality degradation are accelerated, and the structural safety service is seriously threatened. From the analysis of material mechanics, the concrete cracking is caused because the tensile strength of the concrete is lower than that of tensile stress, the load effects such as constraint deformation and ultimate bearing, the temperature and humidity change, chemical reaction and other non-load effects are all sources for generating the tensile stress, most of the internal factors for generating the tensile stress are from volume shrinkage caused by factors such as reduction of water content in the concrete, temperature change, chemical reaction propulsion and the like, the volume shrinkage runs through the whole life cycle of the concrete, the water dispersion and consumption of the concrete in a plastic stage are severe, the hydration reaction degree is high, early plastic cracking is easy to form, and the concrete is easy to form dry shrinkage cracking in a hardening stage, so that the control of the whole-life shrinkage deformation of the concrete is the key for controlling the concrete cracking.
From the perspective of regulating the internal moisture content of concrete, the prior art generally adopts a mode of adding an internal curing material to reduce the shrinkage of concrete (such as patents CN201911059044.0, cn201710953414.x and the like), when the internal humidity is reduced to a certain degree due to the evaporation or chemical reaction of moisture in the concrete, the internal curing material releases moisture to maintain the relative humidity of a concrete system, but the incorporation of the internal curing material generally reduces the homogeneity of the concrete and reduces the mechanical property of the concrete; from the angle of regulating and controlling cement chemical shrinkage, the prior art adopts a mode of doping an expanding agent (such as patents CN202110677670.7, CN201911140549.X and the like) to reduce concrete shrinkage, calcium sulphoaluminate expanding agents in the expanding agent react with hydration products to generate ettringite, but the ettringite is likely to be decomposed at the temperature of more than 70 ℃, and the concrete cannot be used in the environment with the long-term environmental temperature of more than 70 ℃. From the perspective of controlling hydration heat release, the prior art mainly controls the hydration heat release of cement by adding retarders and hydration temperature rise inhibitors (such as patents CN201811145016.6 and CN 201811145219.5), adding mineral admixtures and other methods, the retarders and the hydration temperature rise inhibitors inhibit the generation of temperature cracks by delaying the hydration heat release, and the retardation effect may cause the problems of insufficient development of concrete strength and the like; from the perspective of enhancing the tensile stress in concrete, the prior art mainly improves the crack resistance of concrete by adding different fibers (such as patents cn201911289478.x, CN201910817650.8, etc.), and the fibers applied in concrete have high alkali resistance requirements and are not suitable for adding steel fiber materials in concrete with insulation requirements.
Calcium-based stone powder is a main byproduct in processing production of machine-made aggregates, ore processing and the like, the yield of the stone powder is increasingly improved along with the progress of a rock processing technology and the expansion of the production scale of the machine-made aggregates, but due to the shortage of the application technology of the stone powder, most of the stone powder collected in factories is treated in a low-price resale, waste landfill or warehouse building and storage mode, so that land resources are wasted, the production cost is increased, and the ecological environment and water sources are polluted. The stone powder is modified and then applied to the concrete again, which is one of effective measures for recycling the stone powder, and the main processing methods comprise mechanical grinding, chemical modification, active mineral admixture complex doping and the like. Patent CN201610919396.9 discloses an anti-cracking limestone powder composite admixture and a preparation method thereof, patent CN201710398483.9 discloses anti-cracking granite stone powder thin-layer plastering mortar, and patent CN201710155133.X discloses anti-cracking and anti-corrosion marine concrete prepared by utilizing machine-made sand with high stone powder content.
Therefore, the technical personnel in the field need to solve the problem of providing a material which can effectively utilize stone powder resources and improve the crack resistance of cement concrete.
Disclosure of Invention
In view of the above, the invention provides a composite material for improving the crack resistance of concrete and a preparation method and application thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
a composite material for improving the crack resistance of concrete comprises the following raw materials: calcium carbonate crystal seeds and calcium carbonate crystal whiskers.
According to the invention, calcium-based stone powder is physically modified to prepare ultrafine calcium carbonate crystal seeds, and high-purity calcium carbonate whiskers prepared by chemical modification are compounded and applied to cement concrete by doping in a reasonable proportion, so that the calcium carbonate crystal seed filling and crystal nucleus effects and the calcium carbonate whisker microfiber crack-resisting effect are exerted, the cracking risk of the whole life process of the concrete is effectively reduced, and meanwhile, the high-quality development of comprehensive utilization of stone powder is promoted.
Preferably, the mass percent of the calcium carbonate crystal seeds is 60-70%, and the mass percent of the calcium carbonate crystal whiskers is 30-40%.
Preferably, the specific surface area of the calcium carbonate seed crystal is more than or equal to 750m 2 (iv) kg; the length of the calcium carbonate whisker is 20-100 mu m, and the length-diameter ratio is 10-25.
Preferably, the preparation method of the calcium carbonate seed crystal comprises the following steps:
(1) grinding: grinding the stone powder for 0.5-1h to obtain a product A;
(2) and (3) negative pressure screening: and (3) carrying out negative pressure screening on the product A, and collecting 45-micron undersize, namely the calcium carbonate crystal seed.
The calcium stone powder is ultrafine through a circulating grinding and screening combined process, after partial stone powder particles are refined through a grinding process, tiny stone powder is extracted through negative pressure screening, the rest large-particle stone powder and newly added large-particle stone powder are continuously ground together, and calcium carbonate crystal seeds with tiny particle size and high specific surface are prepared after the circulating process.
Preferably, the screened sieve consists of a set of sieves with the pore diameters of 80 microns and 45 microns, the 45 micron oversize and 80 micron oversize products B are returned to be ground, then stone powder is added to continue grinding, and the operation is repeated.
Preferably, the stone dust has MB value less than 1.0, CaCO 3 The mass fraction is more than or equal to 80 percent.
Preferably, the preparation method of the calcium carbonate whisker comprises the following steps:
(1) acidifying: adding water into the stone powder, dropwise adding dilute hydrochloric acid until the stone powder is not dissolved, and filtering to obtain a filtrate D;
(2) electrolysis: adding MgCl into the filtrate D 2 As electrolyte, performing electrolysis while introducing CO 2 And (3) gas, preparing a precipitate E through a carbon fixation reaction, and cleaning, dispersing and drying to obtain the calcium carbonate whisker.
The preparation process of the calcium carbonate whisker comprises the following steps: dissolving calcareous stone powder into calcium ions in acid, adding a magnesium chloride solution as a crystal form control agent, electrolyzing calcium-containing electrolyte, reacting the calcium ions with carbon dioxide gas introduced from a cathode to generate calcium carbonate in the process of transferring the calcium ions to the cathode, and controlling the length and the length-diameter ratio of calcium carbonate whiskers through the calcium-magnesium ratio in the electrolyte, the bubble size of the carbon dioxide gas and the ventilation rate; the method adopts stone powder which is low in raw material price and easy to obtain as a raw material to prepare the calcium carbonate crystal seeds and the calcium carbonate crystal whiskers with high added value, the two materials have homogeneity and different appearances and are compounded in a reasonable proportion, the greatest advantages are exerted in a newly-mixed stage and a hardened body stage of the cement concrete, the crack resistance of the concrete is synergistically improved, and a convenient and economic solution is provided for the problem of improving the crack resistance of the concrete.
Preferably, in the step (1), the CaO mass fraction of the stone powder is more than or equal to 45%, and the mass concentration of the dilute hydrochloric acid is 10-20%; the mass ratio of the water to the stone powder is 0.5-1.5;
the mass ratio of the electrolyte calcium to the electrolyte magnesium in the step (2) is 0.5-1; the CO is 2 The concentration of the gas is more than or equal to 65 percent, the aeration rate is 15-25mL/min, and the CO is 2 The average diameter of the bubbles of the gas is less than or equal to 3.5 mm.
Preferably, graphite rods are used as the anode and cathode.
Preferably, the specific steps of electrolysis are as follows: stirring the electrolyte by a blade stirrer, and introducing CO into the cathode of the electrolyte 2 And (3) preparing a precipitate E through a chemical reaction by using gas, filtering the solution after the reaction is finished, ultrasonically dispersing and cleaning the precipitate E by using distilled water according to the solid-to-liquid ratio of 10:1, circularly cleaning and dispersing for 3-4 times, and drying the cleaned precipitate to prepare the calcium carbonate whisker.
According to the preparation method of the composite material for improving the crack resistance of the concrete, the calcium carbonate crystal seeds and the calcium carbonate crystal whiskers are mixed in the powder mixing equipment at the rotating speed of 20-60r/min for 8-12min to obtain the composite material for improving the crack resistance of the concrete.
The composite material for improving the crack resistance of the concrete is applied to the preparation of the concrete.
Preferably, when the water-cement ratio of the concrete is more than or equal to 0.4, the composite material is used by adopting an external doping method, and the external doping amount is 5-10% of the total mass of the cementing material; when the water-cement ratio of the concrete is less than 0.4, the composite material is used by adopting a method of internally doping to replace a cementing material, and the internally doping amount is 10-20% of the total mass of the cementing material.
According to the technical scheme, compared with the prior art, the invention has the following beneficial effects:
(1) the invention adopts the synergistic effect of early strength and later-stage dense filling of crystal nucleus. The chemical activity of the calcium carbonate is far lower than that of cement, and after the calcium carbonate is added into concrete, the dosage of the cement is reduced or the effect of diluted cement slurry is exerted, so that the cracking risk of early hydration of the concrete is reduced; the plane structure of Ca and O atoms in the calcium carbonate crystal seeds is similar to that of a CaO layer in a cement hydration product C-S-H, and calcium carbonate with micron-sized particle size can be used as a growth crystal nucleus of C-S-H gel, so that the cement hydration reaction process is promoted, the early strength of concrete is improved, and the strength is reduced due to the reduction of the consumption of neutralized cement; in the hardened concrete, the calcium carbonate crystal seeds have filling effect and micro-aggregate effect, which is beneficial to increasing the compactness of set cement and strengthening the interface transition region, and improving the crack resistance of the hardened concrete.
(2) The present invention uses whisker microfiber effect. The micron-sized calcium carbonate whiskers with large length-diameter ratio have a fiber effect in cement slurry, can inhibit the generation of cracks in different ages, and particularly in hardened concrete, the calcium carbonate whiskers enhance the bonding strength of aggregate and the slurry, macroscopically shows that the tensile strength in the cement slurry is improved, and the generation and development of micro cracks are effectively inhibited.
(3) The composite material has good compatibility with set cement. The anti-cracking material is mainly made of calcium-based powder, the constituent elements of the anti-cracking material are similar to those of cement hydration products, the calcium-based powder and the cement hydration products have good compatibility, and the working performance of the concrete at a plastic stage is not influenced, and the durability of hardened concrete is not deteriorated.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
Example 1
A preparation method of a composite material for improving the crack resistance of concrete specifically comprises the following steps:
(1) preparing calcium carbonate crystal seeds: the raw material is CaCO 3 Weighing 1000g of stone powder with mass fraction of 87% and MB value of 0.5, placing the stone powder in a ball mill, grinding for 40min by taking 0.03% of triethanolamine as a grinding aid, screening the ground stone powder under negative pressure, wherein a screen consists of a sleeve screen with the aperture of 80 mu m and 45 mu m, returning the oversize products with the aperture of 45 mu m and the oversize products with the aperture of 680 mu m to the ball mill, supplementing a proper amount of unground stone powder and continuously grinding, and every time, the grinding is carried out on the stone powderCollecting 45 μm undersize product, cooling and drying to obtain calcium carbonate crystal seed with specific surface area of 850m 2 /kg；
(2) Preparing calcium carbonate whiskers: weighing 500g of mountain flour which is 49 mass percent of CaO as a raw material, placing the mountain flour in a reaction kettle, adding 1000g of distilled water into the reaction kettle to form a solid-liquid mixture A, dropwise adding 15% dilute hydrochloric acid into the solid-liquid mixture A while stirring until the waste mountain flour is not dissolved, and filtering the mixed solution to obtain a filtrate B; 560g of MgCl was added to the filtrate 2 Preparing the filtrate into electrolyte with the mass ratio of calcium to magnesium being 0.8; adopting direct current and graphite electrode to make electrolytic reaction, adopting blade type stirrer to stir electrolyte, introducing CO into cathode position of electrolyte 2 Gas, CO 2 The concentration of the gas was 75%, the aeration rate was 20mL/min, and the introduced CO was dispersed by a bubble disperser 2 Gas, making the average diameter of the bubbles be 1.2 mm; filtering the solution after the reaction is finished, ultrasonically dispersing and cleaning the precipitate by using distilled water according to the solid-to-liquid ratio of 10:1, circularly cleaning and dispersing for 4 times, and drying the cleaned precipitate to prepare calcium carbonate whiskers with the length of 40 mu m and the length-diameter ratio of 16;
(3) preparing a crack resistance improving material: according to the mass ratio of 65 percent of calcium carbonate crystal seeds to 35 percent of calcium carbonate crystal whiskers, mixing for 10min in powder mixing equipment at the rotating speed of 40r/min to prepare the composite material for improving the crack resistance of concrete.
Example 2
A preparation method of a composite material for improving the crack resistance of concrete specifically comprises the following steps:
(1) preparing calcium carbonate crystal seeds: the raw material is CaCO 3 Weighing 1000g of stone powder with the mass fraction of 89% and the MB value of 0.4, placing the stone powder into a ball mill, grinding for 40min by taking 0.03% of triethanolamine as a grinding aid, screening the ground stone powder under negative pressure, wherein a screen consists of a sleeve screen with the pore diameter of 80 mu m and 45 mu m, returning oversize products with the pore diameter of 45 mu m and oversize products with the pore diameter of 680 mu m to the ball mill, supplementing a proper amount of unground stone powder and continuously grinding, collecting undersize products with the pore diameter of 45 mu m in each operation, cooling and drying to prepare calcium carbonate crystal seeds, and the specific surface area of the calcium carbonate crystal seeds is 810m 2 /kg；
(2) Preparing calcium carbonate crystal whiskers: weighing 500g of mountain flour with CaO mass fraction of 50% as a raw material, placing the mountain flour into a reaction kettle, adding 1000g of distilled water into the reaction kettle to form a solid-liquid mixture A, dropwise adding 15% dilute hydrochloric acid into the solid-liquid mixture A while stirring until the waste mountain flour is not dissolved any more, and filtering the mixed solution to obtain a filtrate B; 605g of MgCl was added to the filtrate 2 Preparing the filtrate into electrolyte with the mass ratio of calcium to magnesium of 0.85; adopting direct current and graphite electrode to make electrolytic reaction, adopting blade type stirrer to stir electrolyte, introducing CO into cathode position of electrolyte 2 Gas, CO 2 The concentration of the gas was 75%, the aeration rate was 15mL/min, and the introduced CO was dispersed by a bubble disperser 2 Gas, so that the average diameter of the bubbles is 0.5 mm; filtering the solution after the reaction is finished, ultrasonically dispersing and cleaning the precipitate by using distilled water according to the solid-to-liquid ratio of 10:1, circularly cleaning and dispersing for 4 times, and drying the cleaned precipitate to prepare calcium carbonate whiskers with the length of 50 mu m and the length-diameter ratio of 19;
(3) preparing the anti-cracking performance improving material: and mixing the calcium carbonate crystal seeds 65 percent and the calcium carbonate crystal whiskers 35 percent for 10min in powder mixing equipment at a rotating speed of 40r/min to prepare the anti-cracking performance improving material.
Example 3
A preparation method of a composite material for improving the crack resistance of concrete specifically comprises the following steps:
(1) preparing calcium carbonate crystal seeds: the raw material is CaCO 3 Weighing 1000g of stone powder with the mass fraction of 90% and the MB value of 0.6, placing the stone powder into a ball mill, grinding for 40min by taking 0.03% of triethanolamine as a grinding aid, screening the ground stone powder under negative pressure, wherein a screen consists of a sleeve screen with the pore diameter of 80 mu m and 45 mu m, returning oversize products with the pore diameter of 45 mu m and oversize products with the pore diameter of 680 mu m to the ball mill, supplementing a proper amount of unground stone powder and continuously grinding, collecting undersize products with the pore diameter of 45 mu m in each operation, cooling and drying to prepare the calcium carbonate crystal seed with the specific surface area of 840m 2 /kg；
(2) Preparing calcium carbonate crystal whiskers: the raw material is limestone powder with CaO mass fraction of 48%, 500g of limestone powder is weighed and placed in a reaction kettle, 1000g of distilled water is added into the reaction kettle, and the mixture is shapedForming a solid-liquid mixture A, dropwise adding dilute hydrochloric acid with the concentration of 15% into the solid-liquid mixture A while stirring until the waste stone powder is not dissolved, and filtering the mixed solution to obtain a filtrate B; 617g MgCl was added to the filtrate 2 Preparing the filtrate into electrolyte with the mass ratio of calcium to magnesium being 0.9; adopting direct current and graphite electrode to make electrolytic reaction, adopting blade type stirrer to stir electrolyte, introducing CO into cathode position of electrolyte 2 Gas, CO 2 The concentration of the gas is 85%, the aeration rate is 15mL/min, and a bubble disperser is used for dispersing the introduced CO 2 Gas, making the average diameter of the bubbles be 0.5 mm; filtering the solution after the reaction is finished, ultrasonically dispersing and cleaning the precipitate by using distilled water according to the solid-to-liquid ratio of 10:1, circularly cleaning and dispersing for 4 times, and drying the cleaned precipitate to prepare calcium carbonate whiskers with the length of 50 mu m and the length-diameter ratio of 22;
(3) preparing a crack resistance improving material: and mixing the calcium carbonate crystal seeds and the calcium carbonate crystal whiskers for 10min in powder mixing equipment at a rotating speed of 40r/min according to the mass ratio of 60% of the calcium carbonate crystal seeds to 40% of the calcium carbonate crystal whiskers to obtain the composite material for improving the crack resistance of the concrete.
Application example
1. Example 1 application of the material in concrete: example 1 the admixture amount of the material was 8% by mass of cement, wherein the material of example 1 was set as comparative examples 1 to 1 without addition, crystal seeds of calcium carbonate alone were set as comparative examples 1 to 2, crystal whiskers of calcium carbonate alone were set as comparative examples 1 to 3, the concrete admixture was as shown in the following table 1,
TABLE 1 application example 1 concrete mixing proportion (each component unit: kg/m) 3 )
2. Example 2 application of the material in concrete: example 2 the material was blended in an amount of 20% by mass of the cement, wherein the material of example 2 was set as comparative example 2-1 without addition of the material, crystal seeds of calcium carbonate alone were set as comparative example 2-2, crystal whiskers of calcium carbonate alone were set as comparative example 2-3, the concrete formulation was as shown in table 2 below,
table 2 application example 2 concrete mixing proportion (each component unit is: kg/m) 3 )
3. Example 3 application of the material in concrete: example 3 material replacement amount of 15% by mass of cement, wherein the material of example 3 was not added as comparative example 3-1, the seed crystal of calcium carbonate alone was added as comparative example 3-2, and the whisker of calcium carbonate alone was added as comparative example 3-3, the concrete formulation was as shown in table 3 below,
TABLE 3 application example 3 concrete mixing ratio (each component unit: kg/m) 3 )
The properties of the concrete prepared according to the above application examples 1 to 3 and the comparative example are shown in the following table 4:
table 4 application examples 1-3 concrete performance results
| Numbering | 28d compressive Strength (MPa) | 24h Plastic shrinkage (mu epsilon) | Drying shrinkage (mu epsilon) of 90d |
| Comparative examples 1 to 1 | 38.5 | 1765 | 535 |
| Comparative examples 1 to 2 | 40.3 | 1341 | 501 |
| Comparative examples 1 to 3 | 39.6 | 1453 | 418 |
| Application example 1 | 40.8 | 1241 | 322 |
| Comparative example 2-1 | 51.1 | 1438 | 348 |
| Comparative examples 2 to 2 | 51.5 | 1103 | 302 |
| Comparative examples 2 to 3 | 51.3 | 1287 | 341 |
| Application example 2 | 51.8 | 932 | 235 |
| Comparative example 3-1 | 70.4 | 1326 | 296 |
| Comparative examples 3 to 2 | 70.3 | 1117 | 241 |
| Comparative examples 3 to 3 | 70.1 | 1236 | 226 |
| Application example 3 | 70.2 | 929 | 189 |
From the test results of application examples 1-3 and the comparative examples thereof, it can be seen that after the calcium carbonate whiskers and the crystal seeds are added into different types of concrete to synergistically improve the crack resistance of the concrete, the strength of the concrete is not obviously reduced or even slightly improved, and the strength grade of the concrete is not deteriorated by adding or adding the material provided by the invention.
The crack resistance of the fresh concrete is generally characterized by a plastic shrinkage value, the plastic shrinkage is tested after the fresh concrete is initially set, and the smaller the measured value is, the better the crack resistance of the concrete is; the crack resistance of hardened concrete is generally characterized by a drying shrinkage value, the drying shrinkage is tested after the concrete is cured for 3d, and the smaller the measured value is, the better the crack resistance of the concrete is; from the test data in table 4, it can be seen that the concrete without adding the anti-cracking material has a large plastic shrinkage value and a large dry shrinkage value, and the concrete has poor crack resistance; the concrete with the calcium carbonate crystal seeds is obviously reduced in plastic shrinkage value, but is not greatly reduced in drying shrinkage value, so that the calcium carbonate crystal seeds singly doped only contribute to the crack resistance in the fresh mixing stage; the concrete with the calcium carbonate crystal whisker is obviously reduced in drying shrinkage value and not reduced in plastic shrinkage value, which shows that the calcium carbonate crystal whisker singly doped only contributes to the crack resistance of a hardened body; when the material is only added, the plastic shrinkage value and the drying shrinkage value of the concrete are both obviously reduced, which shows that the calcium carbonate crystal whiskers and the crystal seeds play a role in synergistically improving the crack resistance of the concrete in the whole life stage.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The composite material for improving the crack resistance of concrete is characterized by comprising the following raw materials: calcium carbonate crystal seeds and calcium carbonate crystal whiskers.
2. The composite material for improving the crack resistance of concrete according to claim 1, wherein the mass percent of the calcium carbonate crystal seeds is 60-70%, and the mass percent of the calcium carbonate crystal whiskers is 30-40%.
3. The composite material for improving the crack resistance of concrete according to claim 1 or 2, wherein the specific surface area of the calcium carbonate seed crystal is more than or equal to 750m 2 Per kg; the length of the calcium carbonate whisker is 20-100 mu m, and the length-diameter ratio is 10-25.
4. The composite material for improving the crack resistance of concrete according to claim 1 or 2, wherein the preparation method of the calcium carbonate crystal seeds comprises the following steps:
(1) grinding: grinding the stone powder for 0.5-1h to obtain a product A;
(2) and (3) negative pressure screening: and (3) carrying out negative pressure screening on the product A, and collecting 45-micron undersize, namely the calcium carbonate crystal seed.
5. The composite material for improving the crack resistance of concrete as claimed in claim 4, wherein the MB value of the stone powder is less than 1.0, CaCO 3 The mass fraction is more than or equal to 80 percent.
6. The composite material for improving the crack resistance of concrete according to claim 1 or 2, wherein the preparation method of the calcium carbonate whiskers comprises the following steps:
(1) acidifying: adding water into stone powder, dropwise adding dilute hydrochloric acid until the stone powder is not dissolved, and filtering to obtain filtrate D;
(2) electrolysis: adding MgCl into the filtrate D 2 Then used as electrolyte to carry out electrolysis, and CO is introduced in the electrolysis process 2 And (3) gas, preparing a precipitate E through a carbon fixation reaction, and cleaning, dispersing and drying to obtain the calcium carbonate whisker.
7. The composite material for improving the crack resistance of concrete according to claim 6, wherein the CaO mass fraction of the stone powder in the step (1) is not less than 45%, and the mass concentration of the dilute hydrochloric acid is 10-20%; the mass ratio of the water to the stone powder is 0.5-1.5;
the mass ratio of the electrolyte calcium to the electrolyte magnesium in the step (2) is 0.5-1; the CO is 2 The concentration of the gas is more than or equal to 65 percent, the aeration rate is 15-25mL/min, and the CO is 2 The average diameter of the bubbles of the gas is less than or equal to 3.5 mm.
8. The preparation method of the composite material for improving the crack resistance of the concrete is characterized in that calcium carbonate crystal seeds and calcium carbonate crystal whiskers are mixed in powder mixing equipment at a rotating speed of 20-60r/min for 8-12min to obtain the composite material for improving the crack resistance of the concrete.
9. Use of a composite material according to any one of claims 1 to 7 for improving the crack resistance of concrete in the preparation of concrete.
10. The application of the concrete as claimed in claim 9, wherein when the water-cement ratio of the concrete is more than or equal to 0.4, the composite material is used by adopting an external doping method, and the external doping amount is 5-10% of the total mass of the cementing material; when the water-cement ratio of the concrete is less than 0.4, the composite material is used by adopting a method of replacing the cementing material with internal doping, and the internal doping amount is 10-20% of the total mass of the cementing material.
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| CN103628124A (en) * | 2013-11-12 | 2014-03-12 | 西安交通大学 | Low-voltage direct-current electrolysis preparation method of calcium carbonate whisker |
| CN109704674A (en) * | 2019-01-16 | 2019-05-03 | 湖北大学 | A kind of whisker reinforcement dry slag pervious concrete |
| CN110054456A (en) * | 2019-04-26 | 2019-07-26 | 大连理工大学 | A kind of cement base surface material with high-temperature damage self-repair function |
| CN111620623A (en) * | 2020-05-20 | 2020-09-04 | 大连理工大学 | Cement concrete surface material with high wear resistance and preparation method thereof |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103628124A (en) * | 2013-11-12 | 2014-03-12 | 西安交通大学 | Low-voltage direct-current electrolysis preparation method of calcium carbonate whisker |
| CN109704674A (en) * | 2019-01-16 | 2019-05-03 | 湖北大学 | A kind of whisker reinforcement dry slag pervious concrete |
| CN110054456A (en) * | 2019-04-26 | 2019-07-26 | 大连理工大学 | A kind of cement base surface material with high-temperature damage self-repair function |
| CN111620623A (en) * | 2020-05-20 | 2020-09-04 | 大连理工大学 | Cement concrete surface material with high wear resistance and preparation method thereof |
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Application publication date: 20220902 |