CN115745458A - Additive for improving rheological property of cast-in-place pile concrete and preparation method and application thereof - Google Patents
Additive for improving rheological property of cast-in-place pile concrete and preparation method and application thereof Download PDFInfo
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- 239000004567 concrete Substances 0.000 title claims abstract description 132
- 239000000654 additive Substances 0.000 title claims description 19
- 230000000996 additive effect Effects 0.000 title claims description 18
- 238000002360 preparation method Methods 0.000 title abstract description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 38
- 229920000642 polymer Polymers 0.000 claims abstract description 27
- 125000004185 ester group Chemical group 0.000 claims abstract description 21
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims abstract description 14
- 229920000578 graft copolymer Polymers 0.000 claims abstract description 14
- 239000002994 raw material Substances 0.000 claims abstract 2
- 239000000463 material Substances 0.000 claims description 24
- 239000000203 mixture Substances 0.000 claims description 19
- 239000000843 powder Substances 0.000 claims description 18
- 239000004568 cement Substances 0.000 claims description 17
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 15
- 239000011707 mineral Substances 0.000 claims description 15
- 239000004576 sand Substances 0.000 claims description 15
- 239000004575 stone Substances 0.000 claims description 15
- 239000002253 acid Substances 0.000 claims description 13
- 239000003638 chemical reducing agent Substances 0.000 claims description 13
- 239000010881 fly ash Substances 0.000 claims description 13
- 238000005303 weighing Methods 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 8
- DZSVIVLGBJKQAP-UHFFFAOYSA-N 1-(2-methyl-5-propan-2-ylcyclohex-2-en-1-yl)propan-1-one Chemical compound CCC(=O)C1CC(C(C)C)CC=C1C DZSVIVLGBJKQAP-UHFFFAOYSA-N 0.000 claims description 6
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 6
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 6
- QZPSOSOOLFHYRR-UHFFFAOYSA-N 3-hydroxypropyl prop-2-enoate Chemical compound OCCCOC(=O)C=C QZPSOSOOLFHYRR-UHFFFAOYSA-N 0.000 claims description 6
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 6
- 229940051841 polyoxyethylene ether Drugs 0.000 claims description 6
- 229920000056 polyoxyethylene ether Polymers 0.000 claims description 6
- 238000010526 radical polymerization reaction Methods 0.000 claims description 6
- 229920000877 Melamine resin Polymers 0.000 claims description 5
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 claims description 5
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical group [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 claims description 4
- SZHIIIPPJJXYRY-UHFFFAOYSA-M sodium;2-methylprop-2-ene-1-sulfonate Chemical compound [Na+].CC(=C)CS([O-])(=O)=O SZHIIIPPJJXYRY-UHFFFAOYSA-M 0.000 claims description 4
- IIACRCGMVDHOTQ-UHFFFAOYSA-N sulfamic acid Chemical class NS(O)(=O)=O IIACRCGMVDHOTQ-UHFFFAOYSA-N 0.000 claims description 4
- 239000011398 Portland cement Substances 0.000 claims description 3
- -1 alkylbenzene sulfonate Chemical class 0.000 claims description 3
- KWSLGOVYXMQPPX-UHFFFAOYSA-N 5-[3-(trifluoromethyl)phenyl]-2h-tetrazole Chemical compound FC(F)(F)C1=CC=CC(C2=NNN=N2)=C1 KWSLGOVYXMQPPX-UHFFFAOYSA-N 0.000 claims description 2
- 125000001931 aliphatic group Chemical group 0.000 claims description 2
- 229910001870 ammonium persulfate Inorganic materials 0.000 claims description 2
- 239000012986 chain transfer agent Substances 0.000 claims description 2
- 239000003999 initiator Substances 0.000 claims description 2
- LNOPIUAQISRISI-UHFFFAOYSA-N n'-hydroxy-2-propan-2-ylsulfonylethanimidamide Chemical compound CC(C)S(=O)(=O)CC(N)=NO LNOPIUAQISRISI-UHFFFAOYSA-N 0.000 claims description 2
- 229910001379 sodium hypophosphite Inorganic materials 0.000 claims description 2
- 238000003756 stirring Methods 0.000 claims description 2
- RSWGJHLUYNHPMX-UHFFFAOYSA-N Abietic-Saeure Natural products C12CCC(C(C)C)=CC2=CCC2C1(C)CCCC2(C)C(O)=O RSWGJHLUYNHPMX-UHFFFAOYSA-N 0.000 claims 1
- KHPCPRHQVVSZAH-HUOMCSJISA-N Rosin Natural products O(C/C=C/c1ccccc1)[C@H]1[C@H](O)[C@@H](O)[C@@H](O)[C@@H](CO)O1 KHPCPRHQVVSZAH-HUOMCSJISA-N 0.000 claims 1
- 150000004985 diamines Chemical class 0.000 claims 1
- KHPCPRHQVVSZAH-UHFFFAOYSA-N trans-cinnamyl beta-D-glucopyranoside Natural products OC1C(O)C(O)C(CO)OC1OCC=CC1=CC=CC=C1 KHPCPRHQVVSZAH-UHFFFAOYSA-N 0.000 claims 1
- 239000003795 chemical substances by application Substances 0.000 abstract description 2
- 238000006703 hydration reaction Methods 0.000 description 15
- 230000036571 hydration Effects 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 9
- 238000010276 construction Methods 0.000 description 9
- 238000002156 mixing Methods 0.000 description 9
- 230000000694 effects Effects 0.000 description 7
- 230000003111 delayed effect Effects 0.000 description 5
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 229910001424 calcium ion Inorganic materials 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 239000011376 self-consolidating concrete Substances 0.000 description 4
- 239000004094 surface-active agent Substances 0.000 description 4
- 238000005086 pumping Methods 0.000 description 3
- 230000002787 reinforcement Effects 0.000 description 3
- 206010016807 Fluid retention Diseases 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 230000000740 bleeding effect Effects 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 238000005345 coagulation Methods 0.000 description 2
- 238000005553 drilling Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- QVDTXNVYSHVCGW-ONEGZZNKSA-N isopentenol Chemical compound CC(C)\C=C\O QVDTXNVYSHVCGW-ONEGZZNKSA-N 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 239000004570 mortar (masonry) Substances 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- ASUAYTHWZCLXAN-UHFFFAOYSA-N prenol Chemical compound CC(C)=CCO ASUAYTHWZCLXAN-UHFFFAOYSA-N 0.000 description 2
- 150000004996 alkyl benzenes Chemical group 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 150000004677 hydrates Chemical class 0.000 description 1
- 230000000887 hydrating effect Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 229920005646 polycarboxylate Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 125000001844 prenyl group Chemical group [H]C([*])([H])C([H])=C(C([H])([H])[H])C([H])([H])[H] 0.000 description 1
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- 238000013341 scale-up Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 1
- 239000008030 superplasticizer Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
-
- 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
Abstract
The invention relates to the technical field of concrete admixtures, in particular to an admixture for improving the concrete rheological property of a cast-in-place pile and a preparation method and application thereof. The admixture is prepared from the following raw materials in parts by mass: 15-28 parts of air-entraining component, 25-49 parts of slump retaining component containing ester group, 52-94 parts of water reducing component containing carboxyl graft copolymer and 10-20 parts of polymer component, wherein the molecular structure of the polymer component is a random structure mixed with multi-branched chains and blocks; the air-entraining agent, the slump loss resistant component containing ester groups, the water reducing component containing carboxyl graft copolymer and the polymer component form the admixture within the proportioning range, and the components of the admixture synergistically promote the action, so that the concrete mixed with the admixture has excellent fluidity and workability, good slump loss resistance, working strength guarantee, and good durability, working performance and physical and mechanical properties.
Description
Technical Field
The invention relates to the field of concrete admixtures, in particular to an admixture for improving the concrete rheological property of a cast-in-place pile and a preparation method and application thereof.
Background
With the rapid development of the building industry in China, the construction requirements of various ultra-long, ultra-high and ultra-large concrete structures are continuously increased, the facing geological conditions and building environments are increasingly complex, and the technical requirements on foundation treatment are higher and higher.
The superfluid concrete cast-in-place pile is evolved from a Japanese pile of CIP construction method, the technology utilizes a long spiral drilling machine to carry out rotary drilling in advance to form a hole and press superfluid concrete into the hole, and a reinforcement cage is inserted after the plain concrete pile is formed, so that the superfluid concrete cast-in-place pile has the advantages of high-efficiency hole forming, low noise, no underground water restriction, low cost, high quality, environmental friendliness and the like, and is widely applied after being introduced into China. However, the technology has high requirements on concrete, and the concrete is required to have excellent working performance and physical and mechanical properties, so that the high-flow self-compacting concrete has high strength while ensuring large flow state.
Although China accumulates a great deal of experience in the construction of the cast-in-place pile, some problems exist. For example, commercial concrete of a mixing plant is generally adopted in a construction site, which leads to concrete slump loss in the transportation process; the fluidity of the concrete is not large enough, so that the reinforcement cage cannot be smoothly put down; the poor workability of concrete causes bleeding and segregation, thereby affecting the strength, durability and the like of concrete.
In order to obtain the high-performance super-fluid concrete for the cast-in-place pile, the selection of additives is very important besides the reasonable mixing proportion.
Therefore, it is imperative to find an admixture which can improve the fluidity, workability and slump retention of concrete and ensure the strength and durability of concrete.
Disclosure of Invention
Aiming at the technical problems, the invention provides an additive for improving the rheological property of cast-in-place pile concrete and a preparation method and application thereof. The admixture can improve the fluidity, slump loss resistance and workability of concrete, ensures that all physical mechanical properties and durability of the concrete meet requirements, has better working performance and meets all requirements of cast-in-place pile concrete.
In order to solve the technical problem, the embodiment of the invention adopts the following technical scheme:
in a first aspect, the invention provides an admixture for improving the rheological property of cast-in-place pile concrete, which is prepared from the following components in parts by mass: 15-28 parts of air-entraining component, 25-49 parts of slump retaining component containing ester group, 52-94 parts of water reducing component containing carboxyl graft copolymer and 10-20 parts of polymer component, wherein the molecular structure of the polymer component is a random structure with multi-branched chains and blocks mixed.
Compared with the prior art, the air entraining component, the slump retaining component containing ester groups, the water reducing component containing carboxyl graft copolymer and the polymer component form the admixture within the proportioning range, and the components of the admixture have synergistic promotion effect, so that the concrete mixed with the admixture has excellent fluidity and workability, and good slump retaining performance, the working strength of the concrete is ensured, and the concrete pouring is facilitated.
In the invention, a large amount of uniformly distributed and stably closed 'micro bubbles' can be introduced into the air entraining component in the admixture in the mixing process of the concrete mixture, so that the liquid-air interfacial tension is reduced, the workability, cohesiveness and water retention of the concrete can be effectively improved, and the fluidity of the concrete is obviously improved.
According to the invention, the molecular structure of the slump retaining component in the admixture contains ester groups, and in an alkaline medium of a concrete hydration product, the ester groups and free calcium ions generate an unstable complex, the calcium ion concentration in a liquid phase can be controlled at the initial stage of hydration, and meanwhile, the component can form a stable water film on the cement surface, so that the cement hydration rate can be delayed, the pumpable time of concrete in the construction process can be controlled, the heat release speed of concrete hydration can be delayed and reduced, the slump loss of a concrete mixture can be remarkably reduced, and the concrete has good slump retaining performance. And with the progress of hydration reaction, the complex is continuously decomposed, and the later hydration of the concrete is not influenced.
In the invention, the water reducing component in the additive is a surfactant containing a carboxyl graft copolymer, the molecular structure of the surfactant is comb-shaped, and the main chain of the surfactant is provided with more active groups, so that the surfactant has better dispersibility and slow coagulation effects; the side chain has hydrophilic active groups, can form a net structure, shows a larger three-dimensional repulsion effect, can well disperse cement particles, and releases free water in floccules, so that the concrete has high working strength, and is favorable for pouring the concrete.
In the invention, the molecular structure of the polymer component in the admixture is a random structure with mixed multi-branch chains and blocks, thereby preventing agglomeration among fine particles and improving the fluidity of concrete.
Preferably, the air entraining component is any one of a rosin-provided derivative or an alkylbenzene sulfonate.
In the embodiment of the invention, the air-entraining component can form micro bubbles when the concrete is mixed so as to reduce the liquid-gas interfacial tension, effectively improve the workability, cohesiveness and water retention of the concrete and obviously improve the fluidity of the concrete.
Preferably, the slump retaining component containing an ester group is a slump retaining type polycarboxylic acid water reducing agent, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, hydroxypropyl acrylate and prenyl polyoxyethylene ether are subjected to free radical polymerization reaction, C = C bonds of the four materials are opened, and the four materials are sequentially connected to synthesize the slump retaining type polycarboxylic acid water reducing agent, wherein the molecular number ratio of the four materials is 1-2:2.5-4:5-7:1-2; the initiator is ammonium persulfate and sodium hypophosphite, the dosage of the two materials is 0.5 percent of the total amount, and the proportion of the molecular weight of the two materials is 1:2, sodium methallyl sulfonate is used as a chain transfer agent, and the using amount of the sodium methallyl sulfonate is 0.005 percent of the total amount. The slump-retaining type polycarboxylate superplasticizer can keep the fluidity of concrete not lost, for example, the fluidity is kept above 200mm after half an hour or 1 hour when the initial fluidity is 300mm, and the fluidity is rarely reduced; without adding the slump retaining polycarboxylic acid, the fluidity of the concrete can reach below 100 mm.
In the embodiment of the invention, the polycarboxylic acid water reducing agent synthesized by acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, hydroxypropyl acrylate and isopentenol polyoxyethylene ether through free radical polymerization has an ultra slump retaining effect, mainly because the molecular structure of the polycarboxylic acid water reducing agent contains a large number of ester groups, the ester groups can form an unstable complex with calcium ions in concrete, the concentration of the calcium ions in a liquid phase at the initial stage of concrete hydration can be controlled, and meanwhile, the component can form a stable water film on the surface of the cement, so that the cement hydration rate can be delayed, the pumpable time of the concrete in the construction process can be controlled, the heat release speed of the concrete hydration can be delayed and reduced, and the slump loss of a concrete mixture can be obviously reduced. As the hydration reaction proceeds, the complex is continuously decomposed, and the later hydration of the concrete is not influenced.
Preferably, the water reducing component of the carboxyl-containing graft copolymer is any one of a polycarboxylic acid water reducing agent or citric acid.
In the embodiment of the invention, the preferable water reducing component of the carboxyl-containing graft copolymer has better dispersibility and slow coagulation effect, can fully disperse cement particles, releases free water in floccules, enables the concrete to have high working degree, and is further beneficial to pouring of the concrete.
Preferably, the polymer component is any one of a melamine, a sulfamic acid, or a linear polymer; wherein the melamine comprises a melamine polymer; the aminosulfonic acids include aminosulfonic acid salt polymers; the linear polymer comprises an aliphatic polymer.
In the embodiment of the invention, the molecular structure of the preferable polymer component is a random structure with a multi-branch chain and a block mixed, so that the agglomeration among fine particles can be prevented, and the fluidity of concrete can be improved.
In a second aspect, the invention also provides a preparation method of the admixture, wherein the air-entraining component, the ester-group-containing slump retaining component, the water-reducing component of the carboxyl-containing graft copolymer and the polymer component are uniformly mixed according to a ratio to obtain the admixture.
In the embodiment of the invention, the additive has simple preparation process and low cost, and can be used for industrial scale-up production.
In a third aspect, the invention also provides the application of the admixture for improving the rheological property of the cast-in-place pile concrete, which at least comprises the following steps:
step a: weighing the following components in percentage by mass: 400-420 parts of a cementing material, 880-930 parts of sand, 850-900 parts of stone, 165-170 parts of water and 8-10 parts of an additive are mixed to prepare a stock;
step b: uniformly stirring the prepared materials to obtain a concrete mixture;
step c: and filling the concrete mixture into a mould, demoulding and forming after 1d, and curing for 28d under standard curing conditions to obtain the concrete.
In the embodiment of the invention, the concrete prepared from the admixture has better durability, good working performance and physical and mechanical properties ， And can meet various indexes of slump retaining property, fluidity, workability and the like of the self-compacting concrete, the total slump and the expansion degree within 2 hours can still reach more than 600mm, and the self-compacting concrete has better slump retaining property. The concrete prepared by the admixture can avoid slump loss caused by long-time transportation of the concrete, and is convenient for pumping and pouring of cast-in-place pile concrete. The admixture provides an effective method for preparing the super-fluid concrete, and has higher economic benefit and engineering significance.
In the embodiment of the invention, the concrete obtained by using the additive disclosed by the invention does not need to be vibrated in actual engineering, so that the labor cost and the construction noise can be effectively reduced, the construction efficiency is improved, the concrete is ensured to be well compacted, the degree of freedom of structural design is increased, and the slump loss caused by long-time transportation of the concrete is avoided, thereby facilitating the pumping and pouring of cast-in-place pile concrete.
Preferably, the cementing material is a mixture of cement, fly ash and mineral powder, wherein the cement is ordinary portland cement.
In the embodiment of the invention, the fly ash is class II fly ash, the shape of the fly ash is spherical, the surface of the fly ash is smooth, the rolling friction force among particles can be effectively reduced, and the workability of concrete is improved; the additive can compensate for the shortage of fines in the fine aggregate and inhibit the bleeding of the fresh concrete; the addition of the fly ash can also reduce the hydration heat of concrete, and is suitable for large-volume concrete pouring.
The mineral powder is S95 grade mineral powder, and the specific surface area is more than or equal to 440m 2 /kg。
In the embodiment of the invention, the mineral powder is S95-grade mineral powder, and the surface area is controlled to be 440m 2 More than kg, in the initial stage of cement hydration, mineral powder is wrapped on the surface of cement, so that the mutual overlapping of hydrates in the initial stage of cement is delayed and reduced, and the workability of concrete is improved; the mineral powder has volcanic ash effect, and can absorb Ca (OH) formed by cement hydration 2 And further hydrating to generate C-S-H gel, improving the microstructure of concrete and strengthening the interface binding power of aggregate; the mineral powder and the fly ash are compounded, so that the hydration heat of concrete can be obviously reduced, and the workability of the concrete is improved; in addition, the mineral powder has small fineness, can be filled in gaps of cement particles, exists in concrete in the form of micro aggregate, optimizes the micro pore structure of the concrete, and forms the closest packing, thereby improving the working performance, the mechanical performance and the durability of the concrete.
Preferably, the sand is natural river sand with fineness modulus of 2.6, and the mud content is 0.3-0.6%.
In the embodiment of the invention, river sand is washed by flowing water and waves for a long time, the grains are mostly round and relatively clean, and by controlling the fineness and the mud content of the sand, the obtained sand has stable chemical properties and good grain shape, reduces the water requirement of concrete and effectively improves the strength of the concrete.
Preferably, the stones are 5-15 mm continuous graded crushed stones.
In the embodiment of the invention, the stones are 5-15 mm continuous graded broken stones, so that the mortar quantity for filling the gaps of the aggregate can be reduced, the water consumption per unit volume and the using quantity of the cementing material are correspondingly reduced, and the mixture is not easy to separate. Meanwhile, small stones are easier to pass through the dense reinforcement cages in the cast-in-place pile, and the construction efficiency is improved.
Preferably, the standard curing conditions are 20 + -2 deg.C, 95% + -5% relative humidity.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not delimit the invention.
Example 1
The embodiment of the invention provides a preparation method of an additive for improving the rheological property of cast-in-place pile concrete, which comprises the following steps:
weighing 16 parts of air-entraining component, 28 parts of slump retaining component containing ester group, 79 parts of water reducing component containing carboxyl graft copolymer and 13 parts of polymer component according to the mass parts, and sending the components to a powder mixer for uniform mixing to obtain an additive for improving the rheological property of the cast-in-place pile concrete; the slump loss resistant water reducer is characterized in that an air entraining component is alkylbenzene sulfonate, an ester group-containing slump loss resistant component is an ester group-containing polycarboxylic acid water reducer synthesized by acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, hydroxypropyl acrylate and prenol polyoxyethylene ether through free radical polymerization reaction under the conditions of 1.
Example 2
The embodiment of the invention provides a preparation method of an additive for improving the rheological property of cast-in-place pile concrete, which comprises the following steps:
weighing 20 parts of air-entraining component, 35 parts of slump retaining component containing ester group, 84 parts of water reducing component containing carboxyl graft copolymer and 15 parts of polymer component according to the mass parts, and sending the components to a powder mixer for uniform mixing to obtain an additive for improving the rheological property of the cast-in-place pile concrete; the slump loss resistant agent is a polycarboxylic acid water reducing agent containing ester groups, which is synthesized by acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, hydroxypropyl acrylate and prenol polyoxyethylene ether through free radical polymerization reaction under the conditions of 1.5.
Example 3
The embodiment of the invention provides a preparation method of an additive for improving the rheological property of cast-in-place pile concrete, which comprises the following steps:
weighing 25 parts of air-entraining component, 45 parts of slump retaining component containing ester group, 82 parts of water reducing component containing carboxyl graft copolymer and 16 parts of polymer component in parts by mass, and sending the components to a powder mixer to be uniformly mixed to obtain an additive for improving the rheological property of the cast-in-place pile concrete; the slump retaining component containing the ester group is an ester-group-containing polycarboxylic acid water reducer synthesized by performing free radical polymerization on acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, hydroxypropyl acrylate and isopentenol polyoxyethylene ether under the conditions of 2.
The embodiment of the invention provides the application of the admixture in improving the rheological property of cast-in-place pile concrete, and the admixture prepared in the embodiment 1-3 is used for preparing C30 cast-in-place pile concrete.
Example 4
A, step a: weighing 420 parts of cementing material, 883 parts of sand, 900 parts of stone, 165 parts of water and 10 parts of additive prepared in example 2 in parts by mass, and mixing to prepare a stock;
step b: putting the prepared materials into a concrete mixer to be uniformly mixed to obtain a concrete mixture;
step c: filling the concrete mixture into a mold, demolding after 1d, and molding under standard curing conditions (20 + -2 deg.C, 95% ± 5% relative humidity) for 28d, and obtaining the concrete A1.
Example 5
A, step a: weighing 420 parts of cementing material, 883 parts of sand, 900 parts of stone, 165 parts of water and 4 parts of additive prepared in example 1 in parts by mass, and mixing to prepare a stock;
step b: putting the prepared materials into a concrete mixer to be uniformly mixed to obtain a concrete mixture;
step c: filling the concrete mixture into a mould, demoulding and forming after 1d, and curing under standard curing conditions (20 +/-2 ℃,95% ± 5% relative humidity) for 28d to obtain concrete A2.
Example 6
Step a: weighing 420 parts of cementing material, 883 parts of sand, 900 parts of stone, 165 parts of water and 4 parts of the admixture prepared in the embodiment 3 according to the mass parts, and mixing to prepare a material;
step b: putting the prepared materials into a concrete mixer to be uniformly mixed to obtain a concrete mixture;
step c: filling the concrete mixture into a mold, demolding after 1d, and molding under standard curing conditions (20 + -2 deg.C, 95% ± 5% relative humidity) for 28d to obtain concrete A3.
Comparative example 1
The method for preparing the concrete by adopting the additive in the prior art comprises the following steps:
step a: the admixture adopts a common polycarboxylic acid water reducing agent sold in the market, the solid content is more than or equal to 35 percent, and the water reducing rate is more than or equal to 25 percent;
step b: weighing 420 parts of cementing material, 883 parts of sand, 900 parts of stone, 165 parts of water and 2 parts of commercially available polycarboxylic acid water reducing agent in the step a according to the mass parts, and mixing to prepare a stock;
step c: putting the prepared materials into a concrete mixer to be uniformly mixed to obtain a concrete mixture;
step d: filling the concrete mixture into a mould, demoulding and forming after 1d, and curing under standard curing conditions (20 +/-2 ℃,95% ± 5% relative humidity) for 28d to obtain concrete A4.
The cementitious materials used in examples 4-6 and comparative example 1 above were a mixture of cement, fly ash, and mineral powder, where the cement was p.o.42.5 portland cement and the 28d mortar compressive strength was 52.4MPa; the fly ash is class II fly ash, and the mineral powder is class S95 mineral powder; the sand is natural river sand with fineness modulus of 2.6, and the mud content is 0.3-0.6%; the stones are 5-15 mm continuous graded broken stones.
Verification example 1
The concrete obtained in examples 4 to 6 and comparative example 1 was subjected to quality inspection.
The admixture for improving the rheological property of the cast-in-place pile concrete prepared in the embodiments 1 to 3 of the invention accords with various technical indexes of the concrete admixture in GB50119-2013, and can be used for cast-in-place pile concrete.
The concrete prepared in examples 4 to 6 and comparative example 1 was subjected to performance tests, and the results are shown in Table 1.
TABLE 1 concrete prepared in examples 4 to 6 and comparative example 1 was subjected to performance test
TABLE 2 mechanical Properties of the concretes obtained in examples 4-6 and comparative example 1
| 3d compressive strength/MPa | 7d compressive strength/MPa | 28d compressive strength/MPa | |
| Example 4 (A1) | 17 | 35 | 45 |
| Example 5 (A2) | 19 | 41 | 47 |
| Example 6 (A3) | 21 | 45 | 51 |
| COMPARATIVE EXAMPLE 1 (A4) | 15 | 30 | 38 |
As can be seen from Table 1, the concrete prepared in examples 4 to 6 has an out-machine slump value of 270mm or more, an out-machine expansion value of 625mm or more, a 2h slump value of 215mm or more, a 2h expansion value of 395 or more, and a sum of the 2h slump value and the expansion value of 600mm or more, and has excellent slump retaining property, fluidity and workability, so that the working strength of the concrete is ensured, and all physical and mechanical properties and durability meet the requirements.
As is clear from Table 2, the concrete obtained in examples 4 to 6 has a 3d compressive strength of 17MPa or more, a 7d compressive strength of 35MPa or more, and a 28d compressive strength of 45MPa or more, and the effects are superior to those of comparative example 1. The concrete prepared by the admixture has good working performance and physical and mechanical properties, can meet various indexes of slump retaining property, fluidity, workability and the like of self-compacting concrete, and has excellent slump retaining performance.
Therefore, the concrete prepared by the admixture can meet the requirements on various physical and mechanical properties, has better working performance, and has better comprehensive performance than the concrete in a comparative example. The concrete prepared by the admixture can be better used for long-distance transportation and pumping combined pouring of cast-in-place pile concrete, an effective method is provided for preparation of superfluid concrete, and the concrete has higher economic benefit and engineering significance.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. The admixture for improving the rheological property of the cast-in-place pile concrete is characterized by comprising the following raw materials in parts by mass:
15-28 parts of air-entraining component, 25-49 parts of slump retaining component containing ester group, 52-94 parts of water reducing component containing carboxyl graft copolymer and 10-20 parts of polymer component, wherein the molecular structure of the polymer component is a random structure with multi-branched chains and blocks mixed.
2. The admixture according to claim 1, wherein said air-entraining component is any one of a rosin derivative or an alkylbenzene sulfonate.
3. The admixture according to claim 1, wherein the slump retaining component containing ester groups is a slump retaining polycarboxylic acid water reducing agent, and is synthesized by acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, hydroxypropyl acrylate and isoamylene alcohol polyoxyethylene ether through free radical polymerization, and the molecular number ratio of the four components is 1-2:2.5-4:5-7:1-2, the initiator is ammonium persulfate and sodium hypophosphite, the dosage of the two materials is 0.5 percent of the total amount, and the ratio of the molecular weight of the two materials is 1:2, sodium methallyl sulfonate is used as a chain transfer agent, and the using amount of the sodium methallyl sulfonate is 0.005 percent of the total amount.
4. The admixture according to claim 1, wherein the water-reducing component of the carboxyl group-containing graft copolymer is any one of a polycarboxylic acid water-reducing agent or citric acid.
5. The admixture of claim 1 wherein the polymer component is one or more of a diamine, a sulfamic acid, or a linear polymer; wherein the melamine comprises a melamine polymer; the aminosulfonic acids include aminosulfonic acid salt polymers; the linear polymer includes an aliphatic polymer.
6. The method for preparing the admixture of any one of claims 1 to 5, wherein the air-entraining component, the ester group-containing slump retaining component, the water-reducing component of the carboxyl group-containing graft copolymer and the polymer component are uniformly mixed to obtain the admixture.
7. The use of the admixture according to any one of claims 1 to 5 for improving the rheological properties of cast-in-place pile concrete, characterized in that it comprises at least the following steps:
step a: weighing the following components in percentage by mass: 400-420 parts of a cementing material, 880-930 parts of sand, 850-900 parts of stone, 165-170 parts of water and 8-10 parts of an additive are mixed to prepare a stock;
step b: uniformly stirring the prepared materials to obtain a concrete mixture;
step c: and curing the concrete mixture under standard curing conditions to obtain the concrete.
8. The application of the admixture for improving the rheological property of cast-in-place pile concrete according to claim 7 is characterized in that the cementing material is a mixture of cement, fly ash and mineral powder, wherein the cement is ordinary portland cement; and/or
The fly ash is grade II fly ash; and/or
The mineral powder is S95 grade mineral powder, and the specific surface area is more than or equal to 440m 2 /kg。
9. The application of the admixture for improving the rheological property of cast-in-place pile concrete according to claim 7 is characterized in that the sand is natural river sand with fineness modulus of 2.6, and the mud content is 0.3-0.6%; and/or
The stones are 5-15 mm of continuous graded broken stones.
10. The use of the admixture for improving the rheological properties of cast-in-place pile concrete according to claim 7, wherein the standard curing conditions are 20 ± 2 ℃ and 95% ± 5% relative humidity.
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