CN112794688A - Early-strength low-shrinkage concrete for prefabricated parts and preparation process thereof - Google Patents
Early-strength low-shrinkage concrete for prefabricated parts and preparation process thereof Download PDFInfo
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- CN112794688A CN112794688A CN202110123855.3A CN202110123855A CN112794688A CN 112794688 A CN112794688 A CN 112794688A CN 202110123855 A CN202110123855 A CN 202110123855A CN 112794688 A CN112794688 A CN 112794688A
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
Abstract
The invention discloses early strength low shrinkage concrete for prefabricated parts and a preparation process thereof, wherein the concrete is prepared from the following raw materials in parts by weight: 400 portions of ordinary Portland cement; 1000-1200 parts of coarse aggregate; 500 portions and 600 portions of fine aggregate; 100 portions and 200 portions of biomass incineration ash; 6-10 parts of a low slump type water reducing agent; 4-8 parts of an early strength concrete water reducing agent; 5-10 parts of low slump concrete polymer; 5-10 parts of viscosity-reducing concrete polymer; water 200 and 230 portions. According to the invention, the workability of the fresh concrete is ensured by adding the low slump and viscosity-reducing polymer and the low slump water reducer, the early strength is ensured by adding the early strength concrete water reducer, and the shrinkage of the precast concrete is reduced by taking the biomass incineration ash as an internal curing material.
Description
Technical Field
The invention belongs to the field of silicate materials, relates to a concrete preparation technology, and particularly relates to early-strength low-shrinkage concrete for a prefabricated part and a preparation process thereof.
Background
At present, in bridge roads and various projects, fabricated concrete gradually becomes a trend due to the characteristics of factory prefabrication, standardized construction, reliable quality, high construction speed, high cost performance and the like. Compared with the cast-in-place concrete, the prefabricated part is prepared in advance and then transported to the site for installation, so that the site construction labor is reduced by 80%, the labor intensity of site workers is greatly reduced, and the safe operation of constructors is ensured. The work efficiency is obviously improved while the safety and the quality are ensured. Effectively avoids the pollution of on-site dust, slurry, light, noise and the like, and reduces the influence on the surrounding environment and the life of citizens.
The slump of the concrete for the prefabricated part cannot be too large, otherwise, the concrete can be damaged by collapse, bleeding and the like; the concrete for the prefabricated part needs better plasticity and lower viscosity in order to ensure that the concrete has good construction workability; in some projects, new requirements on the setting time, early strength and the like of the concrete for the prefabricated parts are provided due to problems of transportation, construction period and the like. So that general concrete cannot be used for the preparation of prefabricated parts in large-scale engineering projects.
Disclosure of Invention
The invention aims to provide early-strength low-shrinkage concrete with prefabricated parts and a preparation process thereof. The concrete pouring prefabricated part prepared by the technology can reduce the self-shrinkage of concrete to a great extent, simultaneously ensures better early strength, and can be widely applied to the fields of house construction, municipal pipelines, rail transit, ocean engineering and the like.
The above object of the present invention is achieved by the following technical solutions:
the early strength low shrinkage concrete for the prefabricated part is characterized by comprising the following raw materials in parts by weight:
500 portions and 600 portions of ordinary Portland cement;
1000-1200 parts of coarse aggregate;
500 portions and 600 portions of fine aggregate;
100 portions and 200 portions of biomass incineration ash;
6-10 parts of a low slump type water reducing agent;
4-8 parts of an early strength concrete water reducing agent;
5-10 parts of low slump concrete polymer;
5-10 parts of viscosity-reducing concrete polymer;
water 200 and 230 portions.
To ensure good workability of the concrete, low slump concrete needs to have good plasticity and low viscosity for molding. By adopting the technical scheme, the workability and slump loss of the concrete are adjusted by adding the low-slump water reducing agent, the low-slump polymer, the viscosity-reducing polymer and the like. By adding the prefabricated member early-strength concrete water reducing agent, early-stage hydration of cement is promoted, more CSH is generated in an early age, and early-stage strength of concrete is enhanced. By adding the biomass incineration ash and utilizing the porous characteristic of the biomass incineration ash, water is absorbed and released inside the concrete, the purpose of internal curing is achieved, and the self-shrinkage of the concrete is reduced.
The invention is further configured to: the early-strength low-shrinkage concrete for the prefabricated part is also added with 6-10 parts by weight of a low slump water reducer, and the low slump water reducer is prepared by the following steps:
the method comprises the following steps: adding propylene glycol monoallyl ether and sodium cyanide into a high-pressure reaction kettle provided with a stirrer and temperature control equipment, performing nitrogen replacement for multiple times, then starting vacuumizing, heating to 115-fold organic silicon at 120 ℃, starting vacuum dehydration for 1h, continuing introducing nitrogen for replacement, measuring the oxygen content, controlling the pressure to be less than 0.6MPa after the oxygen content is qualified, cooling to 110-fold organic silicon at 115 ℃, starting continuously introducing an ethylene oxide and propylene oxide uniform mixture, stopping adding nitrogen after the ethylene oxide and the propylene oxide are introduced, performing heat preservation on the high-pressure reaction kettle at 120 ℃ for 2h, aging to a negative pressure, cooling, discharging, and obtaining polyether monomers with molecular weight of about 1600, namely finished polyether;
step two: adding the prepared finished polyether into a reaction kettle, heating to 45-55 ℃ by adopting water bath, and preserving heat for 1-2 hours; preparing diisopropyl peroxydicarbonate, mercaptopropionic acid and water into solution A, preparing acrylic acid, propylene glycol monoallyl ether, sodium formaldehyde sulfoxylate and water into solution B, respectively dropwise adding the solution A and the solution B into a high-pressure reaction kettle by using a dropwise adding pump, dropwise adding the solution A for 2 hours and the solution B for 1.5 hours, adding potassium carbonate into the prepared water reducing agent after the solution A is dropwise added, and supplementing water to the required solid content to obtain the low-slump water reducing agent.
The slump of the concrete is adjusted by adding the low slump type water reducing agent, and the slump loss at 1 hour is 5-15mm, thereby showing excellent slump.
The low slump type water reducing agent adopts polyether as a monomer for synthesizing the water reducing agent, the polyether can increase the flexibility of the branched chain of the water reducing agent, the coating property of water reducing agent molecules on particles is enhanced, and the effective action part of the water reducing agent is improved. The acid-ether ratio of 3.8:1 is adopted in the water reducer, the density of carboxyl and side chains is reasonably controlled, the steric hindrance and the electrostatic repulsion are improved, the adsorption capacity between water reducer molecules and cement particles is considered, and the prepared water reducer molecules have excellent water reduction rate and good adsorption and dispersion properties.
The water reducing agent is designed to be 3.8:1, the prepared 1600 molecular weight long-chain branch has good flexibility and good dispersion and water retention performances in block copolymerization of ethylene oxide and propylene oxide in the branch, and the prepared water reducing agent has excellent slump retention performance.
The invention is further configured to: the early strength concrete water reducing agent is prepared by the following steps:
the method comprises the following steps: adding 2- (allyloxy) phenol and sodium hydroxide into a high-pressure reaction kettle provided with a stirrer and temperature control equipment, performing nitrogen replacement for multiple times, then starting vacuumizing, heating to 122-128 ℃, starting vacuum dehydration for 1.2-1.6h, continuing introducing nitrogen for replacement, measuring the oxygen content, controlling the pressure to be less than 0.4MPa after the oxygen content is qualified, cooling to 115-120 ℃, starting to continuously introduce ethylene oxide and propylene oxide, stopping adding nitrogen after the ethylene oxide and the propylene oxide are introduced, performing heat preservation for 1.7-2.3h in the high-pressure reaction kettle at 122 ℃ of 120-122 ℃, aging to negative pressure, cooling and discharging to obtain crude polyether;
step two: placing the crude polyether in a reaction kettle, replacing the crude polyether for many times under the negative pressure of nitrogen, heating to 119 ℃ for stirring for 0.7-1.8h, cooling to 88-92 ℃, adding distilled water for stirring for 1.5-1.9h, heating to 123 ℃ while vacuumizing, cooling and discharging to obtain a finished polyether product;
step three: adding the prepared finished polyether into a reaction kettle, heating to 46-55 ℃ by adopting water bath, reacting for 2-2.3 hours, preserving heat for 1-1.9 hours, preparing solution A from sodium formaldehyde sulfoxylate, di-tert-butyl peroxide, thioglycolic acid and water, preparing solution B from acrylic acid and water, respectively adding the solution A and the solution B into the reaction kettle by using a dropping pump, wherein the solution A is added for 1.4 hours, and the solution B is added for 1.5 hours, thus preparing the polyether water reducer.
Step four: and adding triethanolamine into the prepared polyether water reducer, and supplementing water to the required solid content to obtain the early-strength concrete water reducer.
By adopting the early-strength concrete water reducing agent, the cement is promoted to hydrate, the CSH number in a hydration product is increased, and the early strength of the concrete is improved.
The polyether is used as a monomer for synthesizing the water reducer, the polyether can increase the flexibility of the branched chain of the water reducer, enhance the coating property of water reducer molecules on particles, and improve the steric hindrance effect of the water reducer. The early strength concrete water reducer of the prefabricated part adopts the acid-ether ratio of 4.2:1, the density of carboxyl and side chains is reasonably controlled, the steric hindrance and the electrostatic repulsion are improved, the adsorption capacity between water reducer molecules and cement particles is considered, and the prepared water reducer molecules have excellent water reduction rate and high adsorption performance.
The 2- (allyloxy) phenol is used as an alcohol head of the synthetic polyether in the prefabricated member early-strength water reducing agent, the length of a benzene ring is smaller than that of a branched chain, the benzene ring is positioned near the main chain of the water reducing agent, the change of a main chain bond angle can be prevented, the rigidity of molecules of the water reducing agent is properly increased, the possibility of winding of the molecules of the water reducing agent is reduced, and the persistence of the dispersing action of the water reducing agent is ensured.
The 4000 molecular weight long-chain branch prepared by the prefabricated member early strength type water reducing agent plays an excellent steric hindrance role, and the high-dispersity water reducing agent molecules improve the uniformity of cement particles in cement paste, so that the cement particles have a reasonable spatial structure, hydration products generated in hydration are reasonably distributed, internal stress cannot be generated, and the early strength of cement is improved.
The invention is further configured to: the low slump concrete polymer is prepared by the following steps:
the method comprises the following steps: adding propylene glycol monoallyl ether and arylsulfonic acid into a high-pressure reaction kettle provided with a stirrer and temperature control equipment, performing nitrogen replacement for multiple times, then starting vacuumizing, then heating to 135-140 ℃ and starting dehydration for 1.3-2h, then continuing introducing nitrogen for replacement, measuring the oxygen content, cooling to 120 ℃ after the oxygen content is qualified, controlling the pressure to be less than 0.6MPa, starting continuously introducing epoxypropane and acetylmethanesulfonic acid, stopping adding nitrogen after the epoxypropane is introduced, performing heat preservation on the high-pressure reaction kettle at 110 ℃ for 2.0h, aging to a negative pressure, cooling and discharging to obtain crude polyether;
step two: placing the crude polyether in a 1L reaction kettle, adding a refining agent, performing nitrogen negative pressure replacement for 3 times, heating to 118 ℃, (stirring for 0.6 h), cooling to 88-91 ℃, adding distilled water, stirring for 1.0-1.6h, heating to 126-;
step three: adding the prepared finished polyether into a reaction kettle, heating to 46-50 ℃ by adopting water bath, reacting for 2.1-2.5 hours, and then preserving heat for 1-2 hours. Preparing a composition of sodium formaldehyde sulfoxylate and sodium metabisulfite in a mass ratio of 1:3, a composition of diisopropyl peroxydicarbonate and di-tert-butyl peroxide in a mass ratio of 1:2, mercaptopropionic acid and water into a solution A, preparing acrylic acid and water into a solution B, respectively dripping the solution A and the solution B into a reaction kettle by using a dripping pump, wherein the dripping of the solution A is 1.2 hours, and the dripping of the solution B is 1.6 hours, so as to prepare a polyether polymer;
step four: and adding a composition of sodium bicarbonate and sodium ethoxide with a mass ratio of 2:3 into the prepared polyether polymer, and supplementing water to the required solid content to obtain a polyether polymer solution, namely the low-slump concrete polymer.
The low slump concrete polymer can promote cement hydration, has a good dispersing effect on cement paste, and improves the performance of concrete.
The low slump concrete polymer introduces ether bonds as branched chain functional groups into polymer molecules, the ether bonds have good flexibility and hydrophilicity, can assist carboxyl on polymer molecular chains to anchor, increase the adaptability of the polymer, enhance the electrostatic repulsion capability of molecular branched chains and enhance the dispersion effect of the polymer.
The polyether alcohol head used by the low slump concrete polymer is propylene glycol monoallyl ether, and the reaction activity is general, so that more initiator is added to promote the polymerization of the polyether alcohol head and an epoxy monomer, and the conversion rate of the reaction is improved.
The polyether prepared from the low slump concrete polymer has a large molecular weight, the prepared polymer branched chain is long, and can play a good steric hindrance role, and the acid-ether ratio of 4.3:1 is designed according to the designed length of the side chain, so that the side chain density is low under the condition of long side chain, the molecular space configuration can be met, and a good adaptive effect is obtained.
The polyether alcohol head used by the low slump concrete polymer is propylene glycol monoallyl ether, and the reaction activity is general, so that more initiator is added to promote the polymerization of the polyether alcohol head and an epoxy monomer, and the conversion rate of the reaction is improved.
The invention is further configured to: the viscosity-reducing concrete polymer is prepared by the following steps:
the method comprises the following steps: adding (4-vinyl phenyl) methanol and lithium aluminum hydride into a high-pressure reaction kettle provided with a stirrer and a temperature control device, then, under the stirring, nitrogen replacement is carried out for a plurality of times, heating is started, the temperature is raised to about 120 ℃, the nitrogen addition is stopped, the pressure is maintained to be relatively constant at 0.25MPaG, then the propylene oxide and the difluoromethanesulfonic acid are slowly introduced into the reactor for induction reaction, the temperature is gradually raised to about 118-120 ℃ in the induction process, maintaining the constant temperature at 130 ℃, preserving the temperature for about 2 hours, adding potassium hydroxide again when the pressure of the reactor is not reduced any more, slowly introducing epoxypropane and difluoromethanesulfonic acid into the container for induction reaction, maintaining the temperature at 135 ℃, reducing the temperature to 110 ℃ when the pressure in the reactor is not reduced any more, vacuumizing and degassing, and discharging to obtain an unsaturated intermediate with the molecular weight of about 400-;
step two: adding the unsaturated intermediate prepared in the step one and deionized water into a four-neck flask to serve as a bottom material, adding acrylic acid and deionized water to serve as a material A, preparing mercaptopropionic acid, mercaptoacetic acid, sodium hypophosphite and deionized water in a mass ratio of 1:2 into a material B, and adding ammonium persulfate and deionized water to prepare a material C; heating a water bath kettle to 35-45 ℃, placing a four-neck flask filled with basic materials into the water bath kettle, adding 1/3C materials at one time, dropwise adding A materials and B materials at a constant speed, dropwise adding the A materials for 3 hours, dropwise adding the B materials for 3 hours and 10 minutes, adjusting the pH value in the reaction kettle to 4-5 by using dilute sulfuric acid after 1.2 hours of reaction, then adding the rest C materials at one time, adding alkali to neutralize and supplement water to the required solid content after the dropwise adding of the A materials and the B materials is finished, and then naturally cooling to room temperature after 1 hour of curing, namely the low slump concrete polymer.
The solid content of the low slump concrete polymer is about 40%.
The low molecular weight polymer for viscosity reduction type concrete enables more gel to be generated in a cement slurry body, the compactness of the gel is further improved, the appearance of a cement hydration product is changed, the toughening and reinforcing effects are further exerted on the concrete, and the concrete strength is ensured while the concrete viscosity is reduced.
The invention is further configured to: the coarse aggregate in the concrete for the prefabricated member is crushed stone with the thickness of 5-20mm, and the apparent density is 2600-3. The fine aggregate is machine-made sand or river sand with fineness modulus of 2.5-2.8, and the apparent density is 2580-3。
The invention is further configured to: the biomass incineration ash in the early-strength low-shrinkage concrete for the prefabricated part is prepared from rice hullsThe biomass materials such as ash, wheat straw, peanut shell and the like are prepared by burning and grinding. Average grain diameter of 5-25 μm, water absorption rate of more than 12%, SiO2The content is more than 80 percent.
The invention also provides a preparation process of the early-strength low-shrinkage concrete for the prefabricated part, which comprises the following process steps of:
step 2, pouring the concrete mixture prepared in the step 1 into a mold for molding;
and 3, curing the concrete to a certain age, and curing the early-strength low-shrinkage concrete member. .
Compared with the prior art, the invention has the advantages and beneficial effects that:
1. the slump of the concrete is adjusted by adding a low slump type water reducing agent, and the slump loss at 1 hour is in the range of 5-15mm, showing excellent slump.
2. By adopting the prefabricated early-strength concrete water reducing agent, the cement is promoted to hydrate, the CSH number in a hydration product is increased, and the early strength of the concrete is improved.
3. The low slump concrete polymer is adopted to promote the hydration of cement, so that the cement paste can be well dispersed, and the performance of the concrete is improved.
4. By adopting the low molecular weight polymer for viscosity-reducing concrete, more gel is generated in the cement paste body, the compactness of the gel is further improved, the appearance of a cement hydration product is changed, the toughening and reinforcing effects are further exerted on the concrete, and the concrete strength is ensured while the concrete viscosity is reduced.
5. By adopting the biomass incineration ash and utilizing the porous characteristic of the biomass incineration ash to absorb and release water in the concrete, the internal curing effect is achieved, and the self-shrinkage of the concrete is reduced.
Drawings
FIG. 1 is an SEM image of a 7-day-old sample of example 5.
FIG. 2 is an SEM image of a 7-day-old sample of comparative example 2.
Detailed Description
The following examples further illustrate the technical solutions of the present invention, but should not be construed as limiting the scope of the present invention.
The invention provides a low slump type water reducing agent which is prepared by the following steps:
the method comprises the following steps: adding 24.87 parts of propylene glycol monoallyl ether and 1 part of sodium cyanide into a high-pressure reaction kettle provided with a stirrer and a temperature control device, performing nitrogen displacement for 3 times, vacuumizing to gauge pressure of-0.05 MPa, heating to 115 ℃ to perform dehydration for 1h, continuing introducing nitrogen for displacement, measuring the oxygen content, controlling the pressure to be less than 0.6MPa after the oxygen content is qualified (the qualified standard is that the oxygen content is not more than 5pp), cooling to 110 ℃, continuously introducing a uniform mixture of 129.8 parts of ethylene oxide and 175 parts of propylene oxide, stopping adding the nitrogen after the ethylene oxide and the propylene oxide are introduced, preserving the temperature of the high-pressure reaction kettle at 115 ℃ for 2h, aging to negative pressure, cooling and discharging to obtain the polyether monomer with the molecular weight of about 1600.
Step two: adding the prepared finished polyether into a reaction kettle, heating to 45 ℃ by adopting water bath, and preserving heat for 1 hour. Preparing liquid A from 4 parts of diisopropyl peroxydicarbonate, 2 parts of mercaptopropionic acid and 60 parts of water, preparing liquid B from 56 parts of acrylic acid 1 part of propylene glycol monoallyl ether, 4 parts of sodium formaldehyde sulfoxylate and 120 parts of water, respectively dripping the liquid A and the liquid B into a reaction kettle by using a dripping pump, wherein the liquid A is dripped for 2 hours, the liquid B is dripped for 1.5 hours, adding 8.1 parts of potassium carbonate into the reaction kettle once after the liquid A is dripped, and supplementing water until the total mass is 1000 to obtain a water reducer solution, namely the low slump type water reducer.
The invention provides an early strength concrete water reducing agent, which is prepared by the following steps:
the method comprises the following steps: adding 10.89 parts of 2- (allyloxy) phenol and 0.6 part of sodium hydroxide into a high-pressure reaction kettle provided with a stirrer and a temperature control device, performing nitrogen displacement for 3 times, vacuumizing to gauge pressure of-0.098 MPa, heating to 122 ℃, dehydrating for 1.2h, continuously introducing nitrogen for displacement, measuring the oxygen content, cooling to 115 ℃ when the oxygen content is qualified (the qualified standard is that the oxygen content is not more than 5pp), controlling the pressure to be less than 0.4MPa, continuously introducing 63.75 parts of ethylene oxide and 252.43 parts of propylene oxide, stopping adding the nitrogen after the ethylene oxide and the propylene oxide are introduced, preserving the temperature of the high-pressure reaction kettle at 120 ℃ for 1.7h, aging to negative pressure, cooling and discharging to obtain the crude polyether.
Step two: and (3) placing the crude polyether into a reaction kettle, performing nitrogen negative pressure replacement for 3 times, heating to 111 ℃, stirring for 0.7h, cooling to 88 ℃, adding distilled water, stirring for 1.5h, heating to 118 ℃ while vacuumizing, cooling, and discharging to obtain the finished polyether.
Step three: adding the prepared finished polyether into a reaction kettle, heating to 46 ℃ by adopting water bath, reacting for 2 hours, and then preserving heat for 1 hour. 4.7 parts of sodium formaldehyde sulfoxylate, 6.2 parts of di-tert-butyl peroxide, 3.3 parts of thioglycolic acid and water are prepared into solution A, 35.60 parts of acrylic acid and water are prepared into solution B, and A, B is dripped into a reaction kettle by using a dripping pump, wherein the dripping of the solution A is 1.4 hours, and the dripping of the solution B is 1.5 hours. And preparing the polyether water reducer.
Step four: and adding 7.8 parts of triethanolamine into the prepared polyether water reducer, and supplementing water until the total mass is 1000, thereby obtaining the early-strength concrete water reducer.
The invention provides a low slump concrete polymer, which is prepared by the following steps:
the method comprises the following steps: adding 15.2 parts of propylene glycol monoallyl ether and 0.4 part of aryl sulfonic acid into a 1L high-pressure reaction kettle provided with a stirrer and a temperature control device, performing nitrogen displacement for 3 times, vacuumizing to gauge pressure of-0.098 MPa, heating to 140 ℃, dehydrating for 1.3h, continuously introducing nitrogen for displacement, measuring the oxygen content, cooling to 120 ℃ when the oxygen content is qualified (the qualified standard is that the oxygen content is not more than 5pp), continuously introducing 341.8 parts of propylene oxide and 12.8 parts of acetyl methane sulfonic acid, stopping adding the nitrogen after the propylene oxide is introduced, preserving the temperature of the high-pressure reaction kettle at 110 ℃ for 2.0h, aging to negative pressure, cooling and discharging to obtain the crude polyether.
Step two: placing the crude polyether in a 1L reaction kettle, adding a refining agent, performing nitrogen negative pressure replacement for 3 times, heating to 121 ℃, stirring for 0.6h, cooling to 88 ℃, adding distilled water, stirring for 1.0h, heating to 236 ℃ while vacuumizing, filtering to remove a polyether adaptation agent when the moisture of the polyether is less than or equal to 0.08%, obtaining a finished polyether product, and then measuring various indexes of the polyether.
Step three: adding the prepared finished polyether into a reaction kettle, heating to 46 ℃ by adopting water bath, reacting for 2.5 hours, and then preserving heat for 1 hour. Preparing a solution A from 2.3 parts of a composition of sodium formaldehyde sulfoxylate and sodium metabisulfite in a mass ratio of 1:3, 6.5 parts of a composition of diisopropyl peroxydicarbonate and di-tert-butyl peroxide in a mass ratio of 1:2, 1.1 parts of mercaptopropionic acid and water, preparing a solution B from 26.5 parts of acrylic acid and water, and respectively dropwise adding the solution A and the solution B into a reaction kettle by using a dropwise adding pump, wherein the solution A is dropwise added for 1.2 hours, and the solution B is dropwise added for 1.6 hours. To obtain the polyether polymer.
Step four: adding 5.5 parts of a composition of sodium bicarbonate and sodium ethoxide in a mass ratio of 2:3 into the prepared polyether polymer, and supplementing water until the total mass is 1000 to obtain a required polyether polymer solution, namely the low-slump concrete polymer.
The invention also provides a viscosity-reducing concrete polymer, which is prepared by the following steps:
the method comprises the following steps: 22 parts of (4-vinyl phenyl) methanol and 0.10 part of lithium aluminum hydride are added into a high-pressure reaction kettle provided with a stirrer and a temperature control device, then under the stirring, performing nitrogen replacement for 4 times, starting heating, heating to about 120 ℃, stopping adding nitrogen, maintaining the pressure relatively constant at 0.25MPaG, then slowly introducing 80 parts of propylene oxide and 10 parts of difluoromethanesulfonic acid into the reactor for induction reaction, gradually heating to about 120 ℃ in the induction process, and maintaining the constant temperature at 130 ℃, keeping the temperature for about 2 hours, adding 0.12 part of potassium hydroxide again when the pressure of the reactor is not reduced any more, then slowly introducing 300 parts of propylene oxide and 10 parts of difluoromethanesulfonic acid into the container to perform induction reaction, maintaining the temperature at 135 ℃, reducing the temperature to 110 ℃ when the pressure in the reaction container is not reduced any more, vacuumizing, degassing, and discharging to obtain an unsaturated intermediate with the molecular weight of about 400-600.
Step two: adding the unsaturated intermediate prepared in the step one and 220 parts of deionized water into a four-neck flask to serve as a bottom material, adding 50 parts of acrylic acid and 120 parts of deionized water to serve as a material A, preparing 1.2 parts of mercaptopropionic acid and thioglycollic acid in a mass ratio of 1:2, 4.5 parts of sodium hypophosphite and 50 parts of deionized water into a material B, and adding 1.2 parts of ammonium persulfate and 60 parts of deionized water into a material C. Heating a water bath kettle to 35 ℃, placing a four-neck flask filled with basic materials into the water bath kettle, adding 1/3C materials at one time, dropwise adding A materials and B materials at a constant speed, dropwise adding the A materials for 3 hours, dropwise adding the B materials for 3 hours and 10 minutes, adjusting the pH value in the reaction kettle to 5 by using dilute sulfuric acid after the reaction is carried out for 1.2 hours, then adding the rest C materials at one time, adding alkali to neutralize and supplement water to 1000 parts by mass after the dropwise adding of the A materials and the B materials is finished, and naturally cooling to room temperature after 1 hour of curing to obtain the synthesized polymer solution with the mass fraction of about 40%, namely the low slump concrete polymer.
Example 1
The early strength low shrinkage concrete for the prefabricated part is prepared from the following raw materials in parts by weight:
400 parts of ordinary Portland cement;
1000 parts of coarse aggregate;
500 parts of fine aggregate;
100 parts of biomass incineration ash;
6 parts of a low slump type water reducing agent;
4 parts of an early strength concrete water reducing agent;
5 parts of low slump concrete polymer;
5 parts of viscosity-reducing concrete polymer;
200 parts of water.
The process comprises the following steps:
step 2, pouring the concrete mixture prepared in the step 1 into a mold for molding;
and 3, curing the concrete for 28 days to obtain the early-strength low-shrinkage concrete member, and curing to a certain age in the curing process to perform corresponding tests.
Examples 2-6 the procedure was the same as in example 1, and the differences in the raw material components are shown in Table 1.
Table 1 is a table of the raw material content components in the early strength low shrinkage concrete for the prefabricated parts of examples 1 to 6 of the present invention
Wherein the coarse aggregate is continuous graded crushed stone with particle size of 5-20mm, and apparent density of 2650/m3. The fine aggregate is river sand with fineness modulus of 2.5 and apparent density of 2582/m3. The cement is ordinary portland cement.
The biomass incineration ash is prepared by incinerating and grinding biomass materials such as rice hull ash, wheat straw, peanut shell and the like. An average particle diameter of 10 μm, a water absorption of 14%, SiO2The content was 85.6%.
The water is ordinary tap water.
Comparative example 1: the comparison example is different from the example 1 in that the same amount of biomass ash is replaced by fly ash.
Comparative example 2: the difference between the comparative example and the example 1 is that the water reducing agent is a common polycarboxylic acid water reducing agent.
Examples 1-6 and comparative examples 1-2 were prepared using the above materials and procedures.
The performance test data of examples and comparative examples were compared, and the initial slump, 1 hour slump, 3 day strength, 7 day self-shrinkage of examples 1 to 6 and comparative examples 1 to 2 are summarized in Table 2
Table 2 is a table of data of the performance tests of examples 1 to 6 of the present invention and comparative examples 1 and 2
In summary, the concrete prepared by the invention has excellent slump and slump loss, shows better early strength at 3 days and 7 days, and has obviously reduced self-shrinkage rate measured at 7 days. The concrete prepared by the invention has excellent performance, the preparation method is simple, and the preparation method is popularized.
The 7-day-old samples of example 5 and comparative example 2 were subjected to SEM examination, and the results are shown in fig. 1 and 2: as can be seen from the comparison of the figures, comparative example 2 using a common polycarboxylic acid type water reducing agent has a low hydration degree, a low degree of compaction, and a high porosity. The SEM image of example 5 shows that more CSH gel is generated, the hydration degree is higher, the compactness of concrete is higher, the porosity is low, the early strength of the concrete is well enhanced, and the prepared concrete is suitable for preparing prefabricated parts by combining the measured lower self-shrinkage performance.
The above embodiments are merely illustrative of the present invention and are not to be construed as limiting the invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that various combinations, modifications or equivalents may be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention, and the technical solution of the present invention is covered by the claims of the present invention.
Claims (8)
1. The early strength low shrinkage concrete for the prefabricated part is characterized by comprising the following raw materials in parts by weight:
500 portions and 600 portions of ordinary Portland cement;
1000-1200 parts of coarse aggregate;
500 portions and 600 portions of fine aggregate;
100 portions and 200 portions of biomass incineration ash;
6-10 parts of a low slump type water reducing agent;
4-8 parts of an early strength concrete water reducing agent;
5-10 parts of low slump concrete polymer;
5-10 parts of viscosity-reducing concrete polymer;
water 200 and 230 portions.
2. The early strength low shrinkage concrete for prefabricated parts according to claim 1, wherein the low slump type water reducing agent is prepared by the steps of:
the method comprises the following steps: adding propylene glycol monoallyl ether and sodium cyanide into a high-pressure reaction kettle provided with a stirrer and temperature control equipment, performing nitrogen replacement for multiple times, then starting vacuumizing, heating to 115-fold organic silicon at 120 ℃, starting vacuum dehydration for 1h, continuing introducing nitrogen for replacement, measuring the oxygen content, controlling the pressure to be less than 0.6MPa after the oxygen content is qualified, cooling to 110-fold organic silicon at 115 ℃, starting continuously introducing an ethylene oxide and propylene oxide uniform mixture, stopping adding nitrogen after the ethylene oxide and the propylene oxide are introduced, performing heat preservation on the high-pressure reaction kettle at 120 ℃ for 2h, aging to a negative pressure, cooling, discharging, and obtaining polyether monomers with molecular weight of about 1600, namely finished polyether;
step two: adding the prepared finished polyether into a reaction kettle, heating to 45-55 ℃ by adopting water bath, and preserving heat for 1-2 hours; preparing diisopropyl peroxydicarbonate, mercaptopropionic acid and water into solution A, preparing acrylic acid, propylene glycol monoallyl ether, sodium formaldehyde sulfoxylate and water into solution B, respectively dropwise adding the solution A and the solution B into a high-pressure reaction kettle by using a dropwise adding pump, dropwise adding the solution A for 2 hours and the solution B for 1.5 hours, adding potassium carbonate into the prepared water reducing agent after the solution A is dropwise added, and supplementing water to the required solid content to obtain the low-slump water reducing agent.
3. The early strength low shrinkage concrete for prefabricated parts according to claim 1, wherein the early strength type concrete water reducing agent is prepared by the following steps:
the method comprises the following steps: adding 2- (allyloxy) phenol and sodium hydroxide into a high-pressure reaction kettle provided with a stirrer and temperature control equipment, performing nitrogen replacement for multiple times, then starting vacuumizing, heating to 122-128 ℃, starting vacuum dehydration for 1.2-1.6h, continuing introducing nitrogen for replacement, measuring the oxygen content, controlling the pressure to be less than 0.4MPa after the oxygen content is qualified, cooling to 115-120 ℃, starting to continuously introduce ethylene oxide and propylene oxide, stopping adding nitrogen after the ethylene oxide and the propylene oxide are introduced, performing heat preservation for 1.7-2.3h in the high-pressure reaction kettle at 122 ℃ of 120-122 ℃, aging to negative pressure, cooling and discharging to obtain crude polyether;
step two: placing the crude polyether in a reaction kettle, replacing the crude polyether for many times under the negative pressure of nitrogen, heating to 119 ℃ for stirring for 0.7-1.8h, cooling to 88-92 ℃, adding distilled water for stirring for 1.5-1.9h, heating to 123 ℃ while vacuumizing, cooling and discharging to obtain a finished polyether product;
step three: adding the prepared finished polyether into a reaction kettle, heating to 46-55 ℃ by adopting water bath, reacting for 2-2.3 hours, preserving heat for 1-1.9 hours, preparing solution A from sodium formaldehyde sulfoxylate, di-tert-butyl peroxide, thioglycolic acid and water, preparing solution B from acrylic acid and water, respectively adding the solution A and the solution B into the reaction kettle by using a dropping pump, wherein the solution A is added for 1.4 hours, and the solution B is added for 1.5 hours, thus preparing the polyether water reducer;
step four: and adding triethanolamine into the prepared polyether water reducer, and supplementing water to the required solid content to obtain the early-strength concrete water reducer.
4. The early strength low shrinkage concrete for prefabricated parts according to claim 1, wherein the low slump concrete polymer is prepared by the steps of:
the method comprises the following steps: adding propylene glycol monoallyl ether and arylsulfonic acid into a high-pressure reaction kettle provided with a stirrer and temperature control equipment, performing nitrogen replacement for multiple times, then starting vacuumizing, then heating to 135-140 ℃ and starting dehydration for 1.3-2h, then continuing introducing nitrogen for replacement, measuring the oxygen content, cooling to 120 ℃ after the oxygen content is qualified, controlling the pressure to be less than 0.6MPa, starting continuously introducing epoxypropane and acetylmethanesulfonic acid, stopping adding nitrogen after the epoxypropane is introduced, performing heat preservation on the high-pressure reaction kettle at 110 ℃ for 2.0h, aging to a negative pressure, cooling and discharging to obtain crude polyether;
step two: placing the crude polyether in a 1L reaction kettle, adding a refining agent, performing nitrogen negative pressure replacement for 3 times, heating to 118 ℃, (stirring for 0.6 h), cooling to 88-91 ℃, adding distilled water, stirring for 1.0-1.6h, heating to 126-;
step three: adding the prepared finished polyether into a reaction kettle, heating to 46-50 ℃ by adopting water bath, reacting for 2.1-2.5 hours, and then preserving heat for 1-2 hours; preparing a composition of sodium formaldehyde sulfoxylate and sodium metabisulfite in a mass ratio of 1:3, a composition of diisopropyl peroxydicarbonate and di-tert-butyl peroxide in a mass ratio of 1:2, mercaptopropionic acid and water into a solution A, preparing acrylic acid and water into a solution B, respectively dripping the solution A and the solution B into a reaction kettle by using a dripping pump, wherein the dripping of the solution A is 1.2 hours, and the dripping of the solution B is 1.6 hours, so as to prepare a polyether polymer;
step four: and adding a composition of sodium bicarbonate and sodium ethoxide with a mass ratio of 2:3 into the prepared polyether polymer, and supplementing water to the required solid content to obtain a polyether polymer solution, namely the low-slump concrete polymer.
5. The early strength low shrinkage concrete for prefabricated parts according to claim 1, wherein the viscosity-reducing concrete polymer is prepared by the following steps:
the method comprises the following steps: adding (4-vinyl phenyl) methanol and lithium aluminum hydride into a high-pressure reaction kettle provided with a stirrer and a temperature control device, then, under the stirring, nitrogen replacement is carried out for a plurality of times, heating is started, the temperature is raised to about 120 ℃, the nitrogen addition is stopped, the pressure is maintained to be relatively constant at 0.25MPaG, then the propylene oxide and the difluoromethanesulfonic acid are slowly introduced into the reactor for induction reaction, the temperature is gradually raised to about 118-120 ℃ in the induction process, maintaining the constant temperature at 130 ℃, preserving the temperature for about 2 hours, adding potassium hydroxide again when the pressure of the reactor is not reduced any more, slowly introducing epoxypropane and difluoromethanesulfonic acid into the container for induction reaction, maintaining the temperature at 135 ℃, reducing the temperature to 110 ℃ when the pressure in the reactor is not reduced any more, vacuumizing and degassing, and discharging to obtain an unsaturated intermediate with the molecular weight of about 400-;
step two: adding the unsaturated intermediate prepared in the step one and deionized water into a four-neck flask to serve as a bottom material, adding acrylic acid and deionized water to serve as a material A, preparing mercaptopropionic acid, mercaptoacetic acid, sodium hypophosphite and deionized water in a mass ratio of 1:2 into a material B, and adding ammonium persulfate and deionized water to prepare a material C; heating a water bath kettle to 35-45 ℃, placing a four-neck flask filled with basic materials into the water bath kettle, adding 1/3C materials at one time, dropwise adding A materials and B materials at a constant speed, dropwise adding the A materials for 3 hours, dropwise adding the B materials for 3 hours and 10 minutes, adjusting the pH value in the reaction kettle to 4-5 by using dilute sulfuric acid after 1.2 hours of reaction, then adding the rest C materials at one time, adding alkali to neutralize and supplement water to the required solid content after the dropwise adding of the A materials and the B materials is finished, and then naturally cooling to room temperature after 1 hour of curing, namely the low slump concrete polymer.
6. The early strength low shrinkage concrete for prefabricated parts as claimed in claim 1, wherein the coarse aggregate is crushed stone of 5-20mm and has an apparent density of 2600-3The fine aggregate is machine-made sand or river sand with fineness modulus of 2.5-2.8, and the apparent density is 2580-3。
7. The early strength and low shrinkage concrete for prefabricated parts according to claim 1, wherein the biomass incineration ash is prepared by incinerating and grinding one or more biomass materials selected from rice hull ash, wheat straw and peanut shell, the particle size is 5-25 μm, the water absorption rate is not less than 12%, and SiO is2The content is not less than 80%.
8. A process for preparing an early strength low shrinkage concrete for prefabricated parts according to any one of claims 1 to 7, comprising the following process steps:
step 1, uniformly mixing ordinary portland cement, coarse aggregates, fine aggregates, biomass incineration ash, a low-slump water reducer, an early-strength concrete water reducer, a low-slump concrete polymer, a viscosity-reducing concrete polymer and water to prepare a concrete mixture;
step 2, pouring the concrete mixture prepared in the step 1 into a mold for molding;
and 3, curing the concrete to a certain age to obtain the early-strength low-shrinkage concrete member.
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