CN114349384B - Viscosity-reducing water reducer - Google Patents
Viscosity-reducing water reducer Download PDFInfo
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Abstract
The invention discloses a viscosity-reducing water reducer. The viscosity-reducing water reducer is prepared by reacting acrylic acid, 2-methylallyl polyoxyethylene ether, thioglycollic acid, citric acid and hydrogen peroxide to prepare a modified acrylic acid solution, then adding ammonium persulfate to react with the modified acrylic acid solution and hydroxyethyl acrylate aqueous solution by taking isopentenol polyoxyethylene ether as a main chain substance, then adding N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt modified by 3-hydroxy-1-methyltetrazole and tetraethoxysilane for polymerization, and finally adding thermally treated silicon carbide nano whisker. Compared with the prior art, the viscosity-reducing water reducer prepared by the invention has excellent viscosity-reducing effect and water-reducing effect, and can effectively enhance the fluidity of slurry and the compressive strength of concrete.
Description
Technical Field
The invention relates to the technical field of water reducers, in particular to a viscosity-reducing water reducer.
Background
With the development of the age, the construction technology is changed day by day, and the past pumping concrete, self-compacting concrete and sprayed concrete cannot meet the current production requirements. The development of new technologies such as high-strength high-performance concrete has higher requirements on the functions of the concrete, and the concrete has the performances of high strength, low hydration heat, low cost, light weight, sound insulation, high durability and the like. Under the background of further accelerating the urban process, the demand for concrete is larger and larger, the quality demands for cement and concrete are also higher and higher, and in recent years, the concrete technology is a new development bottleneck.
The water reducer plays an important role in reducing the cement consumption, enhancing the concrete performance, reducing the production energy consumption and the like, and becomes an indispensable component in the concrete. The polycarboxylate water reducer is a new generation of high-efficiency water reducer after polynaphthalenesulfonate, polymelamine sulfonate and acetone formaldehyde sulfite high-efficiency water reducer, is a novel concrete admixture with a special structure, has a series of outstanding advantages of high water reducing rate, high slump retention capacity, low doping amount, low alkali content, low shrinkage, environmental friendliness and the like, and is widely applied to concrete production at present. But its strong interaction with clay weakens its dispersing and water reducing ability, and reduces the strength and durability of the hardened concrete. Improving the defects becomes a research focus in the world, and further exploration is needed for the theories of the molecular structure, the dispersion property relation, the rheological property and the like of the polycarboxylate water reducer.
Silicon carbide nanowhisker, a single crystal fiber with few defects and a certain length-diameter ratio, has quite good high temperature resistance and high strength. The prior art has few reports of the application of silicon carbide nanowhiskers in water reducers.
The patent with publication number CN106431060A discloses a viscosity-reducing polycarboxylate water reducer for high-strength concrete, which comprises the following components in parts by weight: the water-reducing PCE mother liquor, the viscosity-reducing PCE mother liquor, the slump-retaining PCE mother liquor, the air entraining agent, the defoaming agent, the coagulant, the rust inhibitor, the preservative and a proper amount of water. The viscosity-reducing type polycarboxylate water reducer adopts three mother solutions of a water-reducing type PCE, a viscosity-reducing type PCE and a slump-retaining type PCE, and can obtain proper evacuation time required by high-strength concrete by adjusting the proportion of the three mother solutions according to the actual raw material conditions of a cementing material, aggregate and the like, so that the viscosity of the high-strength concrete is controlled. However, the method adopts complex functional raw materials, and the synthesized polycarboxylate water reducer has insufficient functional strength.
Disclosure of Invention
In order to achieve the purpose, the invention provides the viscosity-reducing water reducer which has good viscosity-reducing effect and water-reducing performance; meanwhile, the compressive strength of the concrete can be obviously enhanced. The specific technical scheme is as follows:
the viscosity-reducing water reducer is prepared by the following method:
step 1, adding acrylic acid and 2-methylallyl polyoxyethylene ether into a container, and uniformly stirring to prepare a mixed solution;
step 2, adding thioglycollic acid, citric acid and hydrogen peroxide into the mixed solution, and stirring at room temperature; then heating in water bath for reaction, and finally adjusting the pH value to be neutral by adopting sodium hydroxide aqueous solution to obtain modified acrylic acid solution;
step 3, adding the isopentenyl alcohol polyoxyethylene ether and water into a container, and raising the temperature to 50-70 ℃ to prepare an isopentenyl alcohol polyoxyethylene ether solution after the solvent is completely dissolved; respectively adding ammonium persulfate aqueous solution, modified acrylic acid solution and hydroxyethyl acrylate aqueous solution into the isopentenyl alcohol polyoxyethylene ether solution; then keeping the temperature at 40-80 ℃ and reacting for 1-2 hours to obtain a polycarboxylic acid solution; then adding modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt into the polycarboxylic acid solution, and regulating the temperature of the solution to carry out stirring reaction; and then regulating the pH value, and then adding the thermally treated silicon carbide nano whisker and sodium hexametaphosphate, and uniformly mixing to obtain the viscosity-reducing water reducer.
Preferably, in the step 1, the components of the raw materials are as follows in parts by weight: 5-10 parts of acrylic acid and 1-4 parts of 2-methylallyl polyoxyethylene ether.
Preferably, in the step 2, the components of the raw materials are as follows in parts by weight: 0.1 to 0.2 part of thioglycollic acid, 0.5 to 2 parts of citric acid and 0.5 to 2 parts of hydrogen peroxide.
Preferably, in the step 2, the room temperature is 20-25 ℃, the stirring speed is 200-400 r/min, and the stirring time is 10-20 min.
Preferably, the water bath heating reaction in the step 2 is carried out, the water bath heating temperature is 70-80 ℃, and the reaction time is 2-4 h.
Preferably, in the step 3, the components of the raw materials are as follows in parts by weight: 30 to 50 parts of isopentenyl alcohol polyoxyethylene ether, 50 to 70 parts of water, 1 to 3 parts of ammonium persulfate aqueous solution, 3 to 7 parts of modified acrylic acid solution, 5 to 10 parts of hydroxyethyl acrylate aqueous solution, 15 to 30 parts of modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt, 20 to 30 parts of heat-treated silicon carbide nano whisker and 0.5 to 1.5 parts of sodium hexametaphosphate.
The concentration of the ammonium persulfate aqueous solution is 5-15 wt%.
The concentration of the hydroxyethyl acrylate aqueous solution is 0.5-3 wt%.
Preferably, in the step 3, the solution temperature is regulated to carry out stirring reaction, the solution temperature is regulated to be 60-80 ℃, the stirring speed is 50-200 r/min, and the reaction time is 1-3 h.
Preferably, the pH value in the step 3 is adjusted to be 5.0-7.0 by adopting 100g/L sodium hydroxide aqueous solution.
Preferably, the preparation method of the modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt in the step 3 comprises the following steps of:
s1, adding 20-30 parts of N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt and 40-80 parts of methanol into a sealed container, and uniformly stirring to prepare a mixed solution;
s2, dropwise adding 5-10 parts of 3-hydroxy-1-methyltetrahydrofyrrole and 1-5 parts of ethyl orthosilicate into the mixed solution, wherein the dropwise adding speed is 0.5-1 mL/min; then adding 0.1-2 parts of potassium tert-butoxide, vacuumizing the reaction vessel, heating to 50-70 ℃ in water bath, and reacting under stirring condition, wherein the stirring speed is 200-400 r/min, and the stirring time is 20-30 h; filtering the obtained precipitate; and then vacuum drying is carried out at the temperature of 25-35 ℃ to obtain the modified N, N-dimethyl (methacryloyloxyethyl) amino propane sulfonic acid inner salt polymer.
The silicon carbide nano whisker after heat treatment is obtained by treating the silicon carbide nano whisker for 1-3 hours at the temperature of 450-600 ℃.
According to the technical scheme, isopentenol polyoxyethylene ether is used as a monomer, and the viscosity reduction performance and water reduction performance of polycarboxylic acid applied to concrete are improved by grafting modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt on the monomer. The N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt synthesizes an amphoteric polycarboxylate copolymer, contains carboxyl and sulfonic groups, is favorable for forming a double diffusion layer on the surface of cement particles, shows stronger dispersing capability, has good initial fluidity for cement paste, and has better fluidity even in the presence of clay.
The benzene ring group is introduced to the polycarboxylic acid by grafting the 3-hydroxy-1-methyl tetrahydropyrrole to prepare the benzene ring polycarboxylate, and compared with the traditional water reducer, the benzene ring polycarboxylate water reducer has lower sensitivity to clay. The cement paste has good initial fluidity, and the fluidity loss of concrete is small after clay is added. This may be due to the particular steric structure of the benzene ring making it difficult to bond with the clay interlayer. In addition, the concrete structure is improved, the strength of the concrete is obviously improved in the later stage of hydration, and the viscosity reduction and the reinforcing performance are good.
The tetraethoxysilane is hydrolyzed and condensed with N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt to synthesize SiO 2 Core shell nanoparticles. Fine silicone fragments are distributed throughout the sample, some of the larger particles being adsorbed to the SiO 2 The nanoparticles are not allowed to form a continuous and uniform shell. The size of the hybrid nanocomposite is about 400nm, and a part of the hybrid nanocomposite contains a plurality of core-shell nanoparticles, so that the prepared hybrid nanocomposite has a good viscosity reduction effect when applied to concrete.
In the technical scheme, the potassium tert-butoxide is added as a catalyst, and has the functions of transesterification, condensation, rearrangement and polymerization in the reaction of modifying N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt.
Due to the adoption of the technical scheme, compared with the prior art, the viscosity-reducing water reducer and the preparation method thereof have the advantages that: 1) The prepared viscosity-reducing water reducer is grafted and modified with N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt, and has better viscosity-reducing effect and water-reducing performance. 2) The preparation method has the effects of reducing cost, improving the compressive strength of the concrete and delaying the service life in the preparation of the concrete. 3) The water reducer has the advantages of simple synthesis method and easily obtained materials, and is suitable for industrial application.
Detailed Description
Sources of the main raw materials in the examples:
tetralin: nanjing chemical Agents Co., ltd., CAS number: 119-64-2.
Thioglycollic acid: shandong Xinchang chemical engineering Co., ltd., CAS:68-11-1.
Acrylic acid: chemical industry of Wuhan Tian Cheng ChengtaiThe formula: c (C) 3 H 4 O 2 Relative molecular mass: 72.06, cas No.: 79-10-7.
Citric acid: changzhou hundred transport chemical Co., ltd., CAS number: 77-92-9.
Isopentenol polyoxyethylene ether: hydroxyl number of wuhan Hua Xiangke biotechnology limited: 20.5-24.5mgKOH/g, moisture: 0.8, pH: 5.0-7.0.
Ammonium persulfate: baiyun (Shanghai) biotechnology limited company, molecular formula: (NH) 4 ) 2 S 2 O 8 Molecular weight: 228.201, cas number: 7727-54-0.
Hydroxyethyl acrylate: shanghai Haohong biological medicine science and technology Co., ltd., molecular formula: c (C) 5 H 8 O 3 Molecular weight: 116.12, cas number: 818-61-1.
Inner salt of N, N-dimethyl (methacryloyloxyethyl) ammonium propane sulfonic acid: changzhou Yitanang chemical Co., ltd., molecular formula: c (C) 11 H 21 NO 5 S, molecular weight: 279.35, CAS number: 3637-26-1.
3-hydroxy-1-methyltetrahydrophole: hubei Jiu Feng Longhua company, inc., CAS number: 13220-33-2.
Ethyl orthosilicate: guangzhou double peach fine chemical industry Co., ltd., molecular formula: si (OC) 2 H 5 ) 4 Molecular weight: 208.33, cas number: 78-10-4.
Potassium tert-butoxide: shandong Langcheng chemical Co., ltd., molecular formula: c (C) 4 H 9 KO, molecular weight: 112.21, CAS:865-47-4.
Silicon carbide nano whisker with average grain diameter of 50-100nm and specific surface area of 30m 2 /g, source: beijing De Kodak gold technologies Co.
Example 1
The preparation method of the viscosity-reducing water reducer comprises the following steps:
step 1, adding 8 parts of acrylic acid and 2 parts of 2-methylallyl polyoxyethylene ether into a container, and uniformly stirring to prepare a mixed solution;
step 2, adding 0.12 part of thioglycollic acid, 1 part of citric acid and 1 part of hydrogen peroxide into the mixed solution, and stirring at the room temperature of 25 ℃ at the stirring speed of 300r/min; then heating in water bath for reaction at 75 ℃ for 3 hours, and finally adjusting the pH to 7 by adopting 30wt% sodium hydroxide aqueous solution to obtain modified acrylic acid solution;
step 3, adding 40 parts of isopentenyl alcohol polyoxyethylene ether and 60 parts of water into a four-necked bottle, and raising the temperature to 60 ℃ to prepare an isopentenyl alcohol polyoxyethylene ether solution after the solvent is completely dissolved; 2 parts of 10wt% ammonium persulfate aqueous solution, 5 parts of modified acrylic acid solution and 6 parts of 1wt% hydroxyethyl acrylate aqueous solution are respectively added into the isopentenyl alcohol polyoxyethylene ether solution; then keeping the temperature at 60 ℃ and reacting for 1-2 hours to obtain a polycarboxylic acid solution; then 18 parts of modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt is added into the polycarboxylic acid solution, the temperature of the solution is regulated to 70 ℃, stirring reaction is carried out, the stirring speed is 100r/min, and the reaction time is 2h; and then adjusting the pH value to 6.0 by adopting a 100g/L sodium hydroxide aqueous solution to obtain the viscosity-reducing water reducer.
The preparation method of the modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt comprises the following steps of:
s1, adding 25 parts of N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt and 50 parts of methanol into a sealed container, and uniformly stirring to prepare a mixed solution;
s2, 7 parts of 3-hydroxy-1-methyltetrahydrofyrrole and 3 parts of ethyl orthosilicate are dropwise added into the mixed solution, and the dropwise acceleration is 0.8mL/min; then adding 1 part of potassium tert-butoxide, vacuumizing the reaction vessel, heating to 60 ℃ in water bath, and reacting under stirring condition, wherein the stirring speed is 300r/min, and the stirring time is 24h; filtering the obtained precipitate; and then drying in vacuum at 25 ℃ to obtain the modified N, N-dimethyl (methacryloyloxyethyl) amino propane sulfonic acid inner salt polymer.
Example 2
The preparation method of the viscosity-reducing water reducer comprises the following steps:
substantially the same as in example 1, the only difference is that:
the preparation method of the modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt comprises the following steps of:
s1, adding 25 parts of N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt and 50 parts of methanol into a sealed container, and uniformly stirring to prepare a mixed solution;
s2, 3 parts of tetraethoxysilane is dropwise added into the mixed solution, and the dropwise adding speed is 0.8mL/min; then adding 1 part of potassium tert-butoxide, vacuumizing the reaction vessel, heating to 60 ℃ in water bath, and reacting under stirring condition, wherein the stirring speed is 300r/min, and the stirring time is 24h; filtering the obtained precipitate; and then drying in vacuum at 25 ℃ to obtain the modified N, N-dimethyl (methacryloyloxyethyl) amino propane sulfonic acid inner salt polymer.
Example 3
The preparation method of the viscosity-reducing water reducer comprises the following steps:
substantially the same as in example 1, the only difference is that:
the preparation method of the modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt comprises the following steps of:
s1, adding 25 parts of N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt and 50 parts of methanol into a sealed container, and uniformly stirring to prepare a mixed solution;
s2, 7 parts of 3-hydroxy-1-methyltetrahydrofyrrole are dropwise added into the mixed solution, and the dropwise adding speed is 0.8mL/min; then adding 1 part of potassium tert-butoxide, vacuumizing the reaction vessel, heating to 60 ℃ in water bath, and reacting under stirring condition, wherein the stirring speed is 300r/min, and the stirring time is 24h; filtering the obtained precipitate; and then drying in vacuum at 25 ℃ to obtain the modified N, N-dimethyl (methacryloyloxyethyl) amino propane sulfonic acid inner salt polymer.
Comparative example 1
The preparation method of the viscosity-reducing water reducer comprises the following steps:
substantially the same as in example 1, the only difference is that:
the preparation method of the modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt comprises the following steps of:
s1, adding 25 parts of N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt and 50 parts of methanol into a sealed container, and uniformly stirring to prepare a mixed solution;
s2, adding 1 part of potassium tert-butoxide into the mixed solution, vacuumizing a reaction vessel, heating the reaction vessel to 60 ℃ in a water bath, and reacting under the stirring condition, wherein the stirring speed is 300r/min, and the stirring time is 24 hours; filtering the obtained precipitate; and then drying in vacuum at 25 ℃ to obtain the modified N, N-dimethyl (methacryloyloxyethyl) amino propane sulfonic acid inner salt polymer.
Comparative example 2
The preparation method of the viscosity-reducing water reducer comprises the following steps:
step 1, adding 8 parts of acrylic acid and 2 parts of 2-methylallyl polyoxyethylene ether into a container, and uniformly stirring to prepare a mixed solution;
step 2, adding 0.12 part of thioglycollic acid, 1 part of citric acid and 1 part of hydrogen peroxide into the mixed solution, and stirring at the room temperature of 25 ℃ at the stirring speed of 300r/min; then heating in water bath for reaction at 75 ℃ for 3 hours, and finally adjusting the pH to 7 by adopting 30wt% sodium hydroxide aqueous solution to obtain modified acrylic acid solution;
step 3, adding 40 parts of isopentenyl alcohol polyoxyethylene ether and 60 parts of water into a four-necked bottle, and raising the temperature to 60 ℃ to prepare an isopentenyl alcohol polyoxyethylene ether solution after the solvent is completely dissolved; 2 parts of 10wt% ammonium persulfate aqueous solution, 5 parts of modified acrylic acid solution and 6 parts of 1wt% hydroxyethyl acrylate aqueous solution are respectively added into the isopentenyl alcohol polyoxyethylene ether solution; then keeping the temperature at 60 ℃ and reacting for 1-2 hours to obtain a polycarboxylic acid solution; and then adjusting the pH value to 6.0 by adopting a 100g/L sodium hydroxide aqueous solution to obtain the viscosity-reducing water reducer.
Example 4
The preparation method of the viscosity-reducing water reducer comprises the following steps:
step 1, adding 8 parts of acrylic acid and 2 parts of 2-methylallyl polyoxyethylene ether into a container, and uniformly stirring to prepare a mixed solution;
step 2, adding 0.12 part of thioglycollic acid, 1 part of citric acid and 1 part of hydrogen peroxide into the mixed solution, and stirring at the room temperature of 25 ℃ at the stirring speed of 300r/min; then heating in water bath for reaction at 75 ℃ for 3 hours, and finally adjusting the pH to 7 by adopting 30wt% sodium hydroxide aqueous solution to obtain modified acrylic acid solution;
step 3, adding 40 parts of isopentenyl alcohol polyoxyethylene ether and 60 parts of water into a four-necked bottle, and raising the temperature to 60 ℃ to prepare an isopentenyl alcohol polyoxyethylene ether solution after the solvent is completely dissolved; 2 parts of 10wt% ammonium persulfate aqueous solution, 5 parts of modified acrylic acid solution and 6 parts of 1wt% hydroxyethyl acrylate aqueous solution are respectively added into the isopentenyl alcohol polyoxyethylene ether solution; then keeping the temperature at 60 ℃ and reacting for 1-2 hours to obtain a polycarboxylic acid solution; then 18 parts of modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt is added into the polycarboxylic acid solution, the temperature of the solution is regulated to 70 ℃, stirring reaction is carried out, the stirring speed is 100r/min, and the reaction time is 2h; then adopting 100g/L sodium hydroxide aqueous solution to adjust the pH value to 6.0, then adding 58 parts of heat-treated silicon carbide nano whisker and 1.2 parts of sodium hexametaphosphate, stirring and mixing for 30min under the condition of 100 rpm; obtaining the viscosity-reducing water reducer.
The preparation method of the modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt is the same as that in example 1, and is not repeated here.
The silicon carbide nano whisker after heat treatment is obtained by treating the silicon carbide nano whisker for 1h at 500 ℃.
Test example 1
The viscosity-reducing water reducer for high-strength concrete synthesized in the examples and the comparative examples adopts standard cement, the mixing amount is 0.18% of the mass of the cement (folded into solid matters), and the mixing ratio of the concrete is as follows: 420kg/m of cement 3 80kg/m of fly ash 3 80kg/m of mineral powder 3 600kg/m of sand 3 1100kg/m stone 3 150kg/m of water 3 And obtaining the concrete to be tested.
The sources of the main raw materials are as follows:
and (3) cement: 32.5 grade, changshaming lake building materials Co., ltd.
Fly ash: second grade 200 mesh, hebei Uygur autonomous natural building materials science and technology Co.
Mineral powder: first, shijiazu forest mineral Co.Ltd.
Sand: river sand, clear away middle sand.
Stone: broken stone, 5-25 mm, the mineral product processing plant created by the lingshou county.
Compressive strength test:
the compressive strength test of concrete tests the construction waste concrete test piece after curing according to GB/T50081-2002 Standard for test method of mechanical Properties of general concrete, when testing, 5 samples are tested for each sample, the tested test piece is a non-standard cube of 150mm×150mm, the average value of the test is taken, and the test steps are as follows:
1. after the test piece is maintained for 28 days, the test piece is taken out in time for testing, and the surface of the test piece is ensured to be clean;
2. placing the test piece in a test area, keeping the top surface of the test piece vertical to the bearing surface when the test piece is molded, aligning the center of the test piece with the center of a lower pressing plate of the test machine, and properly adjusting the ball seat when the upper pressing plate is close to the test piece or the steel backing plate in the test process, so that the stress is more balanced;
3. the load is continuously and uniformly increased in the test process, and the specific added load is as follows: when the strength grade of the concrete is less than C30, the loading speed is 0.3-0.5 MPa per second; when the strength grade of the concrete is more than or equal to C30 and less than C60, 0.5-0.8 MPa is taken per second; taking 0.8-1.0 MPa per second when the strength grade of the concrete is more than or equal to C60;
4. when the test piece is about to be destroyed and starts to generate sharp deformation, stopping the throttle until the test piece is destroyed, and then recording the destruction load.
The compressive strength is calculated as follows:
wherein: f (f) c Compressive strength (MPa) of the test piece;
f is the maximum load (N) which can be borne by the test piece;
a is the area (mm) of the load applied to the test piece 2 )；
Beta is the size conversion coefficient to be 0.95;
the test results of the test pieces are shown in Table 1.
Test example 2
Testing the fluidity of cement paste:
testing the fluidity of cement paste: the method for detecting the adaptability of the cement is determined by referring to the concrete admixture specified in GB/T8077-2012 "method for testing homogeneity of concrete admixture". In the cement paste mixer, a certain amount of cement, an additive and water are added for mixing. Injecting the stirred clean slurry into a truncated cone circular mold, lifting the truncated cone circular mold, and measuring the maximum diameter of the free flowing of the cement clean slurry on the glass surface.
The requirements for the main equipment are as follows:
a) Double-rotation double-speed cement paste mixer: meets the requirements of JC/T729;
b) Truncated cone circular die: a metal product with an upper opening diameter of 36mm, a lower opening diameter of 60mm, a height of 60mm and a smooth and seamless inner wall;
c) A glass plate: 400mm by 5mm;
the test steps are as follows:
1. the glass plate, truncated circular mold, stirrer and stir pot were kept moist but without water stain, and the glass plate was placed in a horizontal position. Covering the truncated cone circular mould with wet cloth and placing the truncated cone circular mould in the center of the glass plate for standby;
2. 300g of cement was poured into the stirred tank. Adding 0.18% of viscosity reducing water reducer and 105g of water, and immediately stirring in the following manner: slow 120s, stop 15s, then fast 120s;
3. the mixed clean slurry is rapidly injected into a truncated cone circular mold, a scraper is adopted to scrape, then the truncated cone circular mold is rapidly lifted up in the vertical direction, a stopwatch is started to count time, the flowing-out clean slurry flows on a glass plate until the flow time reaches 30min, two directions which are perpendicular to each other are selected, the maximum diameter of a flowing part is measured by a ruler, and the average value is taken as the fluidity of the clean slurry.
The test results of the test pieces are shown in Table 1.
Test example 3
And (3) measuring the water reducing rate of the rubber sand:
and (3) testing the water reducing rate of the rubber sand: the method for detecting the adaptability of the cement is determined by referring to the concrete admixture specified in GB/T8077-2012 "method for testing homogeneity of concrete admixture". Firstly, measuring the water consumption of the reference sand fluidity, then measuring the water consumption of the additive-doped sand fluidity, and calculating to obtain the sand water reduction rate.
The requirements for the main equipment are as follows:
a) The sand mixer meets the JC/T681 requirement;
b) The diving table, the truncated cone circular die, the die sleeve, the cylindrical tamper and the caliper are in accordance with the specification of GB/T2419;
the test steps are as follows:
1. adding water into a pot, adding 450g of cement, placing the pot on a fixing frame, lifting to a fixed position, immediately starting a machine, uniformly adding sand at the same time of starting the second 30s after stirring at a low speed for 30s, turning the machine to a high speed, re-stirring for 30s, stopping stirring for 90s, scraping the blade and the rubber sand on the pot wall into the pot by a spatula within the first 15s, and continuing stirring at the high speed for 60s, wherein the stirring time error of each stage is within 1 s;
2. when the glue sand is mixed, the wet cloth is used for wiping, the inner walls of the glass table surface, the tamping rod, the truncated cone circular die and the die sleeve of the diving table are kept wet but have no water stain, and the glass table surface is placed in the center of the glass table surface and covered with the wet cloth for standby;
3. rapidly filling the mixed rubber sand into a die twice, firstly filling the rubber sand into two thirds of a truncated cone circular die, respectively stamping 5 times in two directions perpendicular to each other by using a spatula, uniformly stamping 15 times from the edge to the center by using a tamping rod, then filling a second layer of rubber sand, filling the rubber sand to be about 20mm higher than the truncated cone circular die, stamping 10 times by using the spatula, and stamping 10 times by using the tamping rod, thereby ensuring that the truncated cone circular die does not move during the rubber sand filling and tamping;
4. taking down the die sleeve after tamping, scraping and trowelling the rubber sand higher than the truncated cone circular die by using a trowel, immediately lifting the truncated cone circular die vertically upwards to be placed on a glass table, immediately starting the jump table, and continuously jumping the jump table for 25 times at a frequency of once per second;
5. after the jump is finished, the flowing diameter of the bottom of the gum sand is measured by a caliper, and the average value of the two diameters which are mutually perpendicular is taken as the flowing degree of the gum sand when the water consumption is expressed in mm.
6. Repeating the steps until the fluidity reaches (180+/-5) mm, wherein the water consumption at the moment is the water consumption M of the standard sand fluidity o ；
7. Adding water and 0.18% of viscosity-reducing water reducer into a pot, uniformly stirring, and measuring the water consumption M when the fluidity of cement mortar doped with the viscosity-reducing water reducer reaches (180+/-5) mm according to the operation steps 1 。
The cement mortar water reduction rate (%) is calculated according to the following formula:
glue sand water reducing rate= (M 0 -M 1 )/M 0 ×100
Wherein:
M 0 -the water consumption in grams (g) for a reference sand flow of (180±5) mm;
M 1 -the water consumption in grams (g) when the mobility of the gum sand doped with the viscosity-reducing water reducer is (180 + -5) mm;
the test results of the test pieces are shown in Table 1.
Test example 4
Slump and expansion method test for concrete mixture
Reference is made to the standard of the common concrete mixture performance test method GB/T50080-2011.
Slump and slump extension tests should be performed as follows:
1. the slump cone and the bottom plate are kept moist, and no clear water is needed on the inner wall of the slump cone and the bottom plate. The bottom plate is placed on a solid horizontal plane, the barrel is placed in the center of the bottom plate, then the pedals on the two sides are stepped on by feet, and the slump barrel is kept at a fixed position during loading;
2. the prepared concrete sample is evenly filled into the cylinder in three layers, and the height of each layer after tamping is about one third of the height of the cylinder. The insertion and the tamping are performed from outside to center along the spiral direction, and each insertion and the tamping are uniformly distributed on the section. The tamper may be slightly tilted when the drum is side concrete. When the bottom layer is inserted and tamped, the tamping rod penetrates through the whole depth, and when the second layer and the top layer are inserted and tamped, the tamping rod is inserted through the layer to the surface of the next layer; when the top layer is poured, the concrete is poured to be higher than the cylinder opening. And in the process of the tamping, if the concrete is sunk below the nozzle, adding the concrete at any time. After the top layer is inserted and smashed, redundant concrete is scraped off, and trowelling is performed by a trowel;
3. after the concrete on the bottom plate of the barrel edge is removed, the slump barrel is lifted vertically and stably. The lifting process of the slump cone is completed within 5-10 s; the whole process from the beginning of the filling to the slump-lifting cylinder should be carried out continuously and completed within 150 s;
4. lifting the slump cylinder, and measuring the height difference between the cylinder height and the highest point of the concrete sample after slump after 30min to obtain the slump value of the concrete mixture;
5. the final maximum diameter and minimum diameter of the concrete after expansion were measured with a steel ruler, and the arithmetic average value thereof was used as the slump expansion value under the condition that the difference between the two diameters was less than 50 mm. The test results are shown in Table 1.
TABLE 1
From test table 1, it can be seen that the indexes of example 1 are better than those of examples 2 to 3 and comparative examples 1 to 2, probably because the viscosity-reducing water reducer synthesized by the invention is a surfactant, wherein the grafting of modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt synthesizes an amphoteric polycarboxylate copolymer, and the grafting of 3-hydroxy-1-methyltetrahydrofyrrole introduces benzene ring groups on the polycarboxylic acid, which may be caused by the special three-dimensional structure of benzene ring making it difficult to combine with clay interlayer, compared with the conventional water reducer;the tetraethoxysilane is hydrolyzed and condensed with N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt to synthesize SiO 2 Core shell nanoparticles, fine silicone fragments distributed throughout the sample. Hydrophobic groups doped into the cement paste are adsorbed on the surfaces of cement particles, hydrophilic groups point to aqueous solution, a single-molecule or multi-molecule adsorption film is formed, and the surface tension of concrete is reduced, so that the solid-liquid interface energy of cement particles and the total energy of cement and aqueous dispersion system are reduced, the thermodynamic stability of a dispersion system is improved, double-diffusion layers are formed on the surfaces of the cement particles, the strong dispersion capability is shown, the cement paste has good fluidity, and the cement paste has good fluidity even in the presence of clay.
When the viscosity-reducing water reducer synthesized by the method is added into a concrete mixture, more bubbles are generated, molecules of the water reducer are directionally arranged on liquid-gas interfaces of the bubbles, and meanwhile, the water reducer has the same charge as that of concrete particles, so that the cement particles are isolated by the bubbles, and the cement particles are prevented from agglomerating. The bubbles have supporting and dispersing functions, so that the relative sliding among particles in the concrete is facilitated, a good water reducing effect is achieved, and the adhesiveness of the concrete is improved.
It can be seen from table 1 that the viscosity-reducing water reducer of example 4 was applied to concrete, and the compressive strength of the concrete could be effectively improved. The reason for this is that: the silicon carbide nano whisker after heat treatment has larger specific surface area, can effectively promote bridging effect in the cement hydration process, and can not damage the fluidity of concrete.
Claims (2)
1. The reducing water reducer is characterized by being prepared by the following steps of:
step 1, adding 5-10 parts of acrylic acid and 1-4 parts of 2-methylallyl polyoxyethylene ether into a container, and uniformly stirring to prepare a mixed solution;
step 2, adding 0.1-0.2 part of thioglycollic acid, 0.5-2 parts of citric acid and 0.5-2 parts of hydrogen peroxide into the mixed solution, and stirring at room temperature; then heating in a water bath at 70-80 ℃ for reaction for 2-4 h, and finally adopting a sodium hydroxide aqueous solution to adjust the pH value to be neutral to obtain a modified acrylic acid solution;
step 3, adding 30-50 parts of isopentenyl alcohol polyoxyethylene ether and 50-70 parts of water into a container, increasing the temperature to 50-70 ℃, and preparing an isopentenyl alcohol polyoxyethylene ether solution after the solvent is completely dissolved; respectively adding 1-3 parts of ammonium persulfate aqueous solution, 3-7 parts of modified acrylic acid solution and 5-10 parts of hydroxyethyl acrylate aqueous solution into the isopentenyl alcohol polyoxyethylene ether solution; then keeping the temperature at 40-80 ℃ and reacting for 1-2 hours to obtain a polycarboxylic acid solution; then adding 15-30 parts of modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt into the polycarboxylic acid solution, regulating the temperature of the solution to 60-80 ℃ and stirring the solution at 50-200 r/min for reaction for 1-3 h; then adjusting the pH value to 5.0-7.0 by using sodium hydroxide aqueous solution, then adding 20-30 parts of silicon carbide nano whisker after heat treatment and 0.5-1.5 parts of sodium hexametaphosphate, and uniformly mixing to obtain the viscosity-reducing water reducer;
the preparation method of the modified N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt in the step 3 comprises the following steps of:
s1, adding 20-30 parts of N, N-dimethyl (methacryloyloxyethyl) aminopropanesulfonic acid inner salt and 40-80 parts of methanol into a sealed container, and uniformly stirring to prepare a mixed solution;
s2, dropwise adding 5-10 parts of 3-hydroxy-1-methyltetrahydrofyrrole and 1-5 parts of ethyl orthosilicate into the mixed solution, wherein the dropwise adding speed is 0.5-1 mL/min; then adding 0.1-2 parts of potassium tert-butoxide, vacuumizing the reaction vessel, heating to 50-70 ℃ in water bath, and reacting under stirring condition, wherein the stirring speed is 200-400 r/min, and the stirring time is 20-30 h; filtering the obtained precipitate; and then vacuum drying is carried out at the temperature of 25-35 ℃ to obtain the modified N, N-dimethyl (methacryloyloxyethyl) amino propane sulfonic acid inner salt polymer.
2. The viscosity reducing water reducing agent of claim 1, wherein: in the step 2, the room temperature is 20-25 ℃, the stirring speed is 200-400 r/min, and the stirring time is 10-20 min.
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