CN113277769A - Zeolite powder used as pumping concrete admixture and preparation method and application thereof - Google Patents
Zeolite powder used as pumping concrete admixture and preparation method and application thereof Download PDFInfo
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- CN113277769A CN113277769A CN202110422301.3A CN202110422301A CN113277769A CN 113277769 A CN113277769 A CN 113277769A CN 202110422301 A CN202110422301 A CN 202110422301A CN 113277769 A CN113277769 A CN 113277769A
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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
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/10—Coating or impregnating
- C04B20/1051—Organo-metallic compounds; Organo-silicon compounds, e.g. bentone
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Abstract
The invention relates to the field of resource recycling, in particular to zeolite powder used as a pumping concrete admixture and a preparation method and application thereof. Liquid isooctyl triethoxy silane is adopted to carry out hole sealing treatment on natural zeolite, and then the treated zeolite is dried and ground to prepare the silane-treated zeolite powder. When the silane-treated zeolite powder is doped into concrete, the early fluidity of a concrete mixture is not obviously reduced due to the doping of the zeolite powder, the production and construction requirements of the pumped concrete can be met, and the optimal doping amount is 10-20 wt% of the cement dosage. The invention solves the problem that the concrete doped with natural zeolite powder is difficult to construct because the fluidity is greatly reduced, and meanwhile, the silane-treated zeolite powder which is sealed in the hardened concrete is deblocked, and the hardened concrete can absorb and store more water, thereby improving the self-curing capability of the concrete and further being beneficial to improving the later strength and the durability of the concrete.
Description
Technical Field
The invention relates to the field of resource recycling, in particular to zeolite powder used as a pumping concrete admixture and a preparation method and application thereof.
Background
In order to save energy and utilize waste, reduce the production cost of concrete and improve the performance of concrete, the modern concrete is often mixed with artificial or natural admixture before or during stirring. Common admixtures are fly ash, ground slag powder, silica fume, zeolite powder, ground calcined (spontaneous combustion) gangue powder and other industrial waste residues.
The admixture has volcanic ash activity, but the microstructure has great difference, wherein, the fly ash is mainly of a glass micro-bead structure, and is beneficial to improving the fluidity of concrete when being doped into the concrete, so that the admixture is widely applied to various concrete projects at present. The admixture of the ground slag powder, the silica fume and the like has a relatively compact microstructure, does not have obvious influence on the fluidity of concrete, and is widely applied to concrete engineering at present. The zeolite powder and the ground and calcined (self-combustion) coal gangue powder are porous structures, and can absorb a large amount of water or additives for mixing concrete after being doped into the concrete, so that the fluidity of the concrete is obviously reduced, and the wide application of the zeolite powder and the ground and calcined (self-combustion) coal gangue powder to the concrete is prevented.
Natural zeolite is an aluminosilicate mineral having a framework structure. According to incomplete statistics, nearly 400 zeolite deposits (points) are found in China and are intensively distributed in developed coastal areas, the total storage capacity is about 30 hundred million tons, the storage capacity is large, the quality is high, the development cost is low, and the advantages are obvious. The zeolite powder has certain volcanic ash activity and a micro-aggregate filling effect, can improve the compactness of concrete to a certain extent, and improves the later strength and durability of the concrete. However, due to the porous structure of the zeolite powder, a large amount of mixing water and additives can be absorbed in the concrete mixing process, so that the flowability of fresh concrete is rapidly reduced, the concrete, particularly the pump concrete, is difficult to construct, and the cheap and environment-friendly admixture can not be widely applied to concrete engineering. Although the defect can be improved by adding sufficient high-efficiency water reducing agent, the required dosage is large, so that the production cost of the concrete is greatly increased, and the wide application of the high-efficiency water reducing agent to the concrete is hindered. Therefore, there is a need to find an economical and effective method to improve the fluidity of zeolite concrete to drive the application of zeolite powder in cement and concrete.
Disclosure of Invention
The invention aims to provide zeolite powder used as an admixture for pump concrete, a preparation method and application thereof, aims to solve the problems of large water absorption and admixture of natural zeolite powder in the concrete mixing process and promote the wide application of zeolite powder in cement and concrete.
The inventors have studied and found that zeolite particles having a predetermined particle diameter are impregnated with silane (isooctyltriethoxysilane) to provide a good pore sealing effect. When the zeolite powder prepared by the zeolite is mixed with concrete, the early fluidity of the concrete mixture can not be obviously reduced, and the construction requirement of pumping concrete can be met. It should be noted that if natural zeolite is ground into powder and impregnated in silane, the powder becomes sticky and it is difficult to prepare the silicalite powder.
Further research shows that isooctyltriethoxysilane is hydrolyzed in an alkaline environment, and hardened concrete is in a high-alkaline environment (pH is 12-13), so that zeolite powder sealed in the early stage in the hardened concrete is deblocked, the hardened concrete is favorable for absorbing and storing more water, the self-curing capability of the concrete is improved, and the later strength and durability of the concrete are improved.
The invention firstly provides zeolite powder used as a pump concrete admixture, which is obtained by crushing and drying natural zeolite, soaking the crushed and dried natural zeolite in silane, filtering, drying and grinding the soaked zeolite powder.
The silane is liquid isooctyltriethoxysilane.
The invention adopts liquid isooctyl trioxysilane to seal holes of natural zeolite, and then dries and grinds the zeolite to obtain zeolite powder treated by silane. When the zeolite powder is used as a concrete admixture, the early-stage (within 1 h) fluidity of a concrete mixture is not obviously reduced due to the doping of the zeolite powder, the production and construction requirements of pump concrete can be met, and the slump loss of the concrete within 30mm within 1 h.
The preparation method of the zeolite powder used as the pumping concrete admixture comprises the following specific steps:
(1) crushing natural zeolite to prepare 1.18-20 mm zeolite particles;
(2) drying the crushed zeolite particles by drying or natural drying, and if drying is adopted, cooling the zeolite particles to room temperature;
(3) and (3) soaking the zeolite particles obtained in the step (2) in liquid silane to enable the silane to permeate into pores of the zeolite, and then filtering, drying and grinding the zeolite particles to obtain the silane-treated zeolite powder.
The silane is isooctyltriethoxysilane.
Further preferably, the natural zeolite particles obtained in the step (2) are soaked in the isooctyltriethoxysilane liquid for 24-48h, so that the silane can fully permeate into the pores of the zeolite. 24-48h are merely exemplary and preferred and are not limiting. The soaking time is based on the silane which can permeate into the pores of the zeolite, and the specific time is related to the particle size and the porous structure of the zeolite. Filtering, oven drying at 100 deg.C for 24 hr or naturally drying, and grinding to specific surface area of not less than 400m2And/kg, obtaining the silane-treated zeolite powder.
The isooctyltriethoxysilane obtained in the step (3) is commercially available, and has the following main specification indexes: the appearance is transparent liquid; dissolving in most organic solvents such as acetone, benzene, diethyl ether, carbon tetrachloride, etc.; the content of isooctyltriethoxysilane is more than or equal to 98.9 percent; the siloxane content is less than or equal to 0.3 percent; the density (25 ℃ C.) was 0.88 g/ml.
The silane-treated zeolite powder prepared in the step (3) meets the requirements of natural zeolite powder for concrete and mortar (JG/T566) on I-grade or II-grade zeolite powder.
The invention also provides application of the zeolite powder prepared by the method as a pumping concrete admixture.
Specifically, silane-treated zeolite powder was used as a concrete admixture to produce C80 and below grade concrete. The optimal mixing amount of the zeolite powder is 10 to 20 weight percent of the cement. The zeolite powder is commonly used for pumping concrete but is not limited thereto, and can also be applied to non-pumping concrete.
When the silane-treated zeolite powder is used for being doped into concrete, the mix proportion of the concrete is designed according to the design rule of the mix proportion of common concrete (JGJ 55), the fluidity of the zeolite powder is detected according to the standard of the performance test method of common concrete mixtures (GB/T50080), and the mechanical property is detected according to the standard of the mechanical property test method of common concrete (GB/T50081). Experiments prove that the early-stage (within 1 h) fluidity of the concrete mixture is not obviously reduced due to the doping of the zeolite powder, and the slump loss of the concrete within 1h is within 30 mm.
Research shows that when the cement substituting rate of zeolite powder is below 15 wt%, the early strength of concrete is reduced very little, and the later strength of concrete is raised compared with that of concrete without zeolite powder, the best substituting rate of zeolite powder treated by silane is 10-20%, and the zeolite concrete with good flowability, high strength and high durability can be prepared by substituting 10-20% of cement with zeolite powder treated by silane.
The silane-treated zeolite powder prepared by the invention is applied to concrete, and can improve the performance of the concrete: firstly, the early fluidity of concrete is not obviously reduced, the technical requirement of concrete pumping is met, secondly, silane can be hydrolyzed under the alkaline condition, and the early hole sealing is unsealed in the hardened concrete (with the pH value of 12-13) by the zeolite powder, so that the self-maintenance of the hardened concrete is facilitated, and the later strength and durability of the concrete are improved.
The invention has the beneficial effects that: the invention adopts silane-treated zeolite powder prepared by impregnating natural zeolite with liquid isooctyltriethoxysilane, is an environment-friendly concrete admixture, is applied to pumping concrete, and can solve the problem that the concrete doped with the natural zeolite powder is difficult to construct due to greatly reduced fluidity. The silane-treated zeolite powder prepared by the invention is applied to concrete and can relieve the situation of shortage of admixture market supply. Because modern concrete widely uses admixture technology, admixture such as fly ash and mineral powder is in short supply.
Drawings
FIG. 1 is a clear isooctyltriethoxysilane liquid used in the examples of the present invention.
Fig. 2 shows the water absorption condition of the natural zeolite powder after dropping water.
FIG. 3 shows the situation that the silane-treated zeolite powder does not absorb water after dripping.
FIG. 4 shows the behavior of the mortar fluidity as a function of time. Wherein: c is standard cement mortar, ZC is cement mortar doped with 15% of natural zeolite powder, and SZC is cement mortar doped with 15% of silane treated zeolite powder.
Detailed Description
The invention is further illustrated by the following examples, which illustrate the salient features and significant improvements of the invention, and which are intended to be illustrative of the invention and are not to be construed as limiting in any way.
Example 1:
in this example the effect of natural zeolite powder and silane treated zeolite powder on cement mortar fluidity was compared. The operation steps are as follows:
(1) crushing natural zeolite to obtain 3-5mm zeolite particles;
(2) fully drying the natural zeolite particles by a natural drying method;
(3) grinding the natural zeolite particles obtained in the step (2) to a specific surface area of 400m2/kg of natural zeolite powder;
(4) soaking the natural zeolite particles obtained in the step (2) in isooctyltriethoxysilane liquid for 48h to ensure that silane fully permeates into zeolite pores, then filtering the zeolite pores, drying the zeolite pores for 24h at 100 ℃, and grinding the zeolite particles to a specific surface area of 400m2Per kg, obtaining silane-treated zeolite powder;
(5) preparing standard cement mortar (cement + standard sand + water) according to a cement mortar fluidity determination method (GB/T2419), simultaneously respectively replacing 15% of cement with the two zeolite powders prepared in the step (3) and the step (4) to prepare zeolite powder cement mortar (cement + zeolite powder + standard sand + water), and then testing the fluidity of the 3 types of mortar every 15 min.
FIG. 1 is a liquid, clear isooctyltriethoxysilane as used in example 1; dripping a drop of water on the natural zeolite powder obtained in the step (3), and finding that the water drops immediately infiltrate into the natural zeolite powder, which shows that the natural zeolite powder has strong water absorption, and the water absorption state after dripping is shown in fig. 2; a drop of water was dropped on the silane-treated zeolite powder obtained in step (4), and the drop of water was found to be spherical, indicating that the silane-treated zeolite powder had remarkable water repellency and the non-water-absorption state after dropping water was as shown in fig. 3.
FIG. 4 shows the results of the 3 mortar fluidity tests in example 1 as a function of time. Tests show that the initial fluidity of the standard cement mortar (C) is 216mm, the fluidity of the standard cement mortar is reduced at the speed of 0.33mm/min, and the fluidity of the standard cement mortar is 196mm when the standard cement mortar is 60 min; the initial fluidity of the cement mortar doped with 15 percent of natural zeolite powder (ZC) is 175mm which is obviously lower than that of C, the fluidity rapidly decreases at the speed of 0.47mm/min to 147mm when 60min, which shows that the fluidity of the cement mortar is obviously reduced by the doping of the natural zeolite powder; the initial fluidity of the zeolite powder cement mortar (SZC) doped with 15 percent of silane is 220mm, which is slightly larger than the initial fluidity of C, the fluidity slowly decreases at the speed of 0.25mm/min, and can still reach 205mm after 60min, which shows that the initial fluidity of the zeolite powder doped with silane is larger than C, and the decrease rate of the fluidity is lower than C, which shows that the zeolite powder doped with silane can delay the decrease of the fluidity of cement mortar.
Example 2:
in this example the effect of natural zeolite powder and silane treated zeolite powder on concrete slump and compressive strength were compared. The operation steps are as follows:
(1) concrete was prepared according to the following 3 mix ratios, respectively. The mixing proportion 1 is standard concrete, the mixing proportion 2 is concrete prepared by replacing 15% of cement with natural zeolite powder, and the mixing proportion 3 is concrete prepared by replacing 15% of cement with silane-treated zeolite powder.
TABLE 1 concrete mix proportion (unit: kg/m)3)
(2) The slump loss of the above 3 types of concrete was measured with time in accordance with Standard test methods for ordinary concrete mixture Properties (GB/T50080), and the results are shown in Table 2. Tests show that the initial slump of the reference concrete (mixing proportion 1) is 200mm, then the initial slump is reduced at the average speed of 0.52mm/min, and the pumping requirement (slump of 175mm) can be still met when the slump is 60 min; the natural zeolite powder replaces 15% of cement to prepare concrete (mixing ratio is 2), the initial slump is 170mm and is obviously lower than the initial slump of the reference concrete, the slump is rapidly reduced, the pumping requirement cannot be met (the slump is 140mm) after 30min, the natural zeolite powder is in a viscous stacking state after 60min, and the pumping property (the slump is 110mm) is completely lost, so that the concrete fluidity can be obviously reduced by doping the natural zeolite powder; the silane-treated zeolite powder is used for replacing 15% cement to prepare concrete (mixing ratio is 3), the initial slump is 210mm and is slightly larger than the initial slump of the reference concrete, then the initial slump is slowly reduced at the average speed of 0.33mm/min, good pumpability (slump is 200mm) is still achieved after 30min, and the slump can still reach 190mm after 60min, so that the reduction of the fluidity of the concrete can be obviously delayed by doping the silane-treated zeolite powder, and the pumpability requirement can be completely met within 1 h.
TABLE 2 concrete slump loss test results over time (mm)
(3) The compressive strengths of the 3 types of concrete after standard curing for 7 days, 28 days and 56 days were respectively tested according to the Standard test methods for mechanical Properties of general concrete (GB/T50081), and the results are shown in Table 3. Tests show that the early strength (7 days) of the concrete is slightly lower than that of the reference concrete by the doping of the zeolite powder, but the later strength (28 days and 56 days) of the concrete is higher than that of the reference concrete, which shows that the zeolite powder has good volcanic ash activity, but the volcanic ash activity is exerted slowly, and the later strength increasing effect on the concrete is obvious. The later strength of the silane-treated zeolite powder for replacing 15% of cement to prepare concrete (mixing ratio 3) is greater than that of the natural zeolite powder for replacing 15% of cement to prepare concrete (mixing ratio 2), which shows that silane can be hydrolyzed in alkaline environment, and in hardened concrete, the silane-treated zeolite powder which is sealed in holes at the early stage is deblocked, so that more water can be absorbed and stored for self-curing of concrete, and the later strength of concrete is improved.
TABLE 3 concrete compressive Strength test results (MPa)
The above examples only show two embodiments of the present invention, and the description thereof is specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, according to the above-mentioned conception of the present invention, after reading the teaching of the present invention, various changes or modifications can be made by those skilled in the art, and these equivalents also fall within the scope of the present invention defined by the appended claims.
Claims (9)
1. The zeolite powder as admixture for pumping concrete is prepared with natural zeolite, and through crushing, drying, soaking in silane, filtering, drying and grinding.
2. The zeolite powder of claim 1, wherein the silane is liquid isooctyltriethoxysilane.
3. The method for preparing zeolite powder according to claim 1, comprising the steps of:
(1) crushing natural zeolite to prepare 1.18-20 mm zeolite particles;
(2) drying the crushed zeolite particles by natural drying or drying, and if drying is adopted, cooling the zeolite particles to room temperature;
(3) and (3) soaking the zeolite particles obtained in the step (2) in liquid silane to enable the silane to permeate into pores of the zeolite, and then filtering, drying and grinding the zeolite particles to obtain the silane-treated zeolite powder.
4. The method for producing zeolite powder according to claim 3, wherein the silane is isooctyltriethoxysilane.
5. The preparation method of claim 4, wherein the natural zeolite particles obtained in step (2) are soaked in the isooctyltriethoxysilane liquid for 24-48 h.
6. The preparation method of claim 4, wherein the silane-impregnated zeolite particles are filtered, dried at 100 ℃ for 24 hours or naturally dried, and ground to a specific surface area of not less than 400m2And/kg, obtaining the silane-treated zeolite powder.
7. Use of the zeolite powder according to claim 1 or 2 as an admixture for concrete.
8. Use according to claim 7, as a concrete admixture of C80 and below.
9. The use as claimed in claim 8, wherein the zeolite powder is incorporated in an amount of 10-20 wt% of the amount of cement.
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CN111620662A (en) * | 2020-06-16 | 2020-09-04 | 湘潭大学 | Concrete doped with modified zeolite |
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AT510635A1 (en) * | 2010-10-18 | 2012-05-15 | Paltentaler Minerals Gmbh & Co Kg | HYDROPHOBIZED ZEOLITE FOR USE IN SILICATE BINDER SYSTEMS |
CN104402289A (en) * | 2014-11-26 | 2015-03-11 | 金华市欣生沸石开发有限公司 | Zeolite cement mortar waterproof agent and preparation method thereof |
CN108424020A (en) * | 2018-05-03 | 2018-08-21 | 黄河勘测规划设计有限公司 | A kind of method for modifying super hydrophobicity of mineral admixture |
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