Modified silicon mortar and preparation method thereof

Abstract

The invention relates to the field of silica mortar, and particularly discloses modified silica mortar and a preparation method thereof.The modified silica mortar is prepared from, by weight, 38-42 parts of silica fume, 0.08-0.12 part of sulfamate water reducing agent, 0.18-0.22 part of cellulose fiber and 57-63 parts of water; the specific surface area of the silica fume is greater than or equal to 15000 m / kg; the preparation method comprises the following steps: S1, uniformly mixing and stirring the silica fume and the cellulosic fibers to obtain a primary mixture; s2, uniformly mixing and stirring a sulfamate water reducing agent and water to obtain a mixture; s3, uniformly mixing and stirring the primary mixture and the mixture, and defoaming to obtain silica mortar; the silica mortar is added into the concrete and has the advantages of high compressive strength, good crack resistance, good fluidity and good settlement resistance.

Description

Technical Field

[0001] The present application relates to the field of silica mortar, and more specifically, to a modified silica mortar and a preparation method thereof. Background Art

[0002] The silica fume particles in traditional silica fume slurry have an extremely high specific surface area, which enhances the silica fume's ability to adsorb water in the slurry, resulting in a decrease in free water inside the slurry and a significant decrease in fluidity, making it difficult to meet the pouring and pumping requirements during construction; and the silica fume particles are relatively dense, and are prone to sedimentation and stratification under the action of gravity, which destroys the uniformity of the slurry, not only affecting construction operations, but also causing uneven structural performance after hardening, reducing the quality of the project; in addition, after the silica fume is slowly added to the concrete, it is difficult to provide sufficient strength in a short period of time, which can easily affect the progress of the construction period.

[0003] In the existing technology, water reducers can improve the fluidity of silica fume slurry through dispersion, but when faced with high silica fume dosage, it is difficult to balance the rheological properties and mechanical properties at the same time; taking naphthalene-based water reducers as an example, it can effectively reduce the surface tension of the slurry, but as the silica fume dosage increases, its dispersion effect gradually weakens, and it will introduce a large number of bubbles, reducing the density of the slurry and affecting the later strength development; although polycarboxylic acid-based water reducers have high water reduction rates and good slump retention, in high-dosage silica fume systems, they will undergo complex reactions with the active groups on the silica fume surface, resulting in a decrease in dispersion stability and difficulty in maintaining a good rheological state of the slurry for a long time.

[0004] In order to balance the viscosity and fluidity of silica ash slurry, cellulose thickeners are often used to regulate the viscosity. When the dosage is insufficient, the sedimentation and stratification of silica ash cannot be effectively suppressed; when the dosage is high, the viscosity of the slurry rises sharply and the fluidity drops sharply. During the concrete pouring process, it may lead to increased pumping resistance and even blockage of the pipeline, delaying the construction period and making it difficult to meet the continuous construction requirements of the project.

[0005] Therefore, how to prepare a new silica mortar to be added to concrete with the advantages of high compressive strength, good crack resistance, good fluidity and good anti-settling properties is a problem to be solved. Summary of the Invention

[0006] In order to prepare a new silica ash mortar that is added to concrete and has the advantages of high compressive strength, good crack resistance, good fluidity and good anti-settling properties, the present application provides a modified silica ash mortar and a preparation method thereof.

[0007] In the first aspect, the present application provides a modified silica mortar, which adopts the following technical solution: A modified silica ash mortar comprises the following raw materials in parts by weight: 38-42 parts of silica ash, 0.08-0.12 parts of aminosulfonate water reducer, 0.18-0.22 parts of cellulose fiber, and 57-63 parts of water; the silica ash has a specific surface area of ​​≥15000m 2 / kg.

[0008] By adopting the above technical solution, the addition amount of silica fume and the specific surface area of ​​silica fume are limited, so that the silica fume can fully participate in the hydration reaction, significantly improving the strength and durability of the concrete, and aminosulfonate can effectively reduce the surface tension of water, reduce the amount of water used, improve the fluidity of the silica fume mortar, and is not likely to affect the setting time and strength of the concrete. At the same time, cellulose fiber has good toughness and elasticity, and can withstand a certain shear force and pressure in the silica fume mortar. Adding it to concrete can inhibit the occurrence of concrete cracks and improve the crack resistance of the concrete; cellulose fiber contains a large number of hydroxyl groups, which can form a cross-linked network in the silica fume mortar, realizing the "anchoring" effect of cellulose fiber on the silica fume mortar, and adding it to concrete makes the concrete have better anti-settling properties.

[0009] Preferably, the cellulose fibers are modified cellulose fibers with an average length of 50-200 μm and an average diameter of 10-30 nm.

[0010] By adopting the above technical solution, the length and diameter of the cellulose fibers are limited, so that the cellulose fibers are evenly distributed in the silica mortar, while playing a connecting and anchoring role, ensuring that the silica mortar has a certain fluidity while having good stability. When the silica mortar is added to the concrete, it is not easy to have the problem of excessive collapse, and the concrete has better strength and anti-settling properties. At the same time, the connecting effect of the cellulose fibers further improves the strength and anti-settling properties of the concrete.

[0011] Preferably, the modified cellulose fiber is prepared from cellulose fiber filaments, polyvinyl alcohol-1799 solution and cystine in a mass ratio of 1:0.1-0.15:0.05-0.1.

[0012] By adopting the above technical solution, cellulose fiber filaments, polyvinyl alcohol-1799 solution and cystine are combined, and polyvinyl alcohol-1799 and cystine are attached to the surface of cellulose fiber in turn. Due to the high degree of alcoholysis of polyvinyl alcohol-1799, it is not easily soluble in water, and the polyvinyl alcohol-1799 solution has a certain waterproof property after film formation, ensuring that the cellulose fiber is not easily over-absorbed by mixing water, thereby ensuring the fluidity of the silica ash slurry.

[0013] The bonding effect of polyvinyl alcohol-1799 solution is utilized to facilitate the adhesion of cystine to the surface of cellulose fiber. Polyvinyl alcohol contains hydroxyl groups, and amino and carboxyl groups in cystine make the modified cellulose fiber and silica mortar attracted through hydrogen bonds. In addition, the sulfur element in cystine on the surface of the modified cellulose fiber and the silicon element in the silica mortar further bind and bond, thereby improving the stability of the silica mortar on the surface of the modified cellulose fiber and ensuring that the silica mortar has good fluidity and good anti-settling properties.

[0014] The polyvinyl alcohol-1799 solution is combined with cystine. The sulfur atom in the cystine molecule can enhance the rigidity of the cross-linked network formed by the modified cellulose fiber in the silica ash mortar through the sulfide bond with polyvinyl alcohol-1799. Combined with the hydrogen bond connection between polyvinyl alcohol-1799 and the hydroxyl groups of silica ash, the silica ash is distributed inside the high-strength cross-linked network and on its surrounding surface, thereby improving the strength and crack resistance of the concrete with added silica ash mortar.

[0015] Preferably, the molecular weight of the aminosulfonate water reducer is 2000-5000, and the sulfonic acid group content is ≥80%.

[0016] By adopting the above technical solution, the sulfonic acid groups in the aminosulfonate water-reducing agent promote the activation of hydroxyl groups on the surface of silica fume, accelerate the pozzolanic reaction, and improve the strength of concrete with the added silica fume mortar; limiting the molecular weight to 2000-5000 optimizes the steric hindrance effect, and can achieve improved fluidity of the net slurry in the silica fume mortar, thereby improving the fluidity. At the same time, its static viscosity gives the silica fume mortar good anti-settling properties; and ≥80% of the sulfonic acid groups in the aminosulfonate molecules are adsorbed on the surface of the silica fume particles through electrostatic repulsion, destroying the flocculation structure, reducing the yield stress of the cement slurry, and ensuring the pumping effect of the concrete.

[0017] Preferably, the silica fume is pretreated silica fume, which is prepared by loading silica fume particles with a cetearyl alcohol polyether-25 melt and then bonding them with magnesium oxide powder. The mass ratio of silica fume particles, cetearyl alcohol polyether-25 melt and magnesium oxide powder is 1:0.05-0.1:0.1-0.15.

[0018] By adopting the above technical scheme, the polar groups of cetearyl alcohol polyether-25 are utilized to facilitate bonding with silica fume, and the barrier effect of magnesium oxide micropowder on the micropores on the surface of silica fume and the film-forming smoothness of the cetearyl alcohol polyether-25 melt are combined to reduce the roughness of the surface of silica fume particles, thereby improving the fluidity and dispersibility of silica fume slurry; and the filling effect of magnesium oxide micropowder on the surface of silica fume is utilized to further improve the density of the slurry, and cetearyl alcohol polyether-25 can form a stable protective layer on the surface of silica fume particles, combined with the dispersing and barrier effect of cellulose fiber, further preventing the sedimentation or aggregation of silica fume in the silica fume slurry, so that the concrete with added silica fume slurry has better anti-settling effect.

[0019] Preferably, the silica slurry further comprises 2-6 parts of filling particles; the filling particles are composed of modified nano-silica and modified hollow glass microspheres in a mass ratio of 1:0.5-1.2.

[0020] By adopting the above technical solution, the surface hydroxyl groups in nano-silica and hollow glass microspheres are connected with polar groups such as hydroxyl groups in cellulose fibers, thereby ensuring the dispersibility of the nano-silica and hollow glass microspheres while improving the stability of the filling particles, making it less likely to have sedimentation and suspension problems. The nano-silica and hollow glass microspheres uniformly distributed in the silica mortar utilize their filling effect and their higher strength to further improve the strength and crack resistance of concrete added with silica mortar.

[0021] Preferably, the modified nano-silica is prepared from nano-silica and silane coupling agent KH-550 in a mass ratio of 1:0.3-0.5.

[0022] By adopting the above technical solution, after the nano-silica is treated with the silane coupling agent KH-550, the amino groups in the silane coupling agent KH-550 molecules are connected to the hydroxyl groups on the surface of the nano-silica, and the ethoxy groups are connected to the organic phase of the silica mortar. Combined with the nano-filling effect of the nano-silica, the strength and crack resistance of the concrete added with the silica mortar are improved.

[0023] Preferably, the modified hollow glass microspheres are prepared by treating hollow glass microspheres with a sodium hydroxide solution, then adding a hydroxyethyl cellulose ether solution, and heating and stirring the mixture; the mass ratio of the hollow glass microspheres, the sodium hydroxide solution, and the hydroxyethyl cellulose ether solution is 1:8-12:8-15.

[0024] By adopting the above technical solution, after the hollow glass microspheres are treated with an alkali solution of sodium hydroxide, the silicon hydroxyl active sites on the surface of the hollow glass microspheres are increased, and the roughness of the hollow glass microspheres is increased to form microscopic grooves, thereby enhancing the anchoring effect with the silica mortar; then, the hollow glass microspheres are mixed with the hydroxyethyl cellulose ether solution. Since the hydroxyethyl cellulose ether is more active under alkaline conditions, the hollow glass microspheres treated with sodium hydroxide are promoted to be cross-linked with the hydroxyethyl cellulose ether in combination with heating and stirring, and can be bonded to the surface of the hollow glass microspheres through bonding force. The shear thinning characteristics of the hydroxyethyl cellulose ether during stirring and pumping are utilized to ensure the fluidity of the silica mortar. When the silica mortar is added to the concrete, the viscosity of the silica mortar can be controlled under hydration, thereby ensuring the anti-settling property of the concrete with the added silica mortar; at the same time, the hydroxyethyl cellulose ether molecular chains can form a flexible cross-linked network after the concrete is cured, which, in combination with the bonding effect between the silica mortar and the concrete, further improves the compressive strength and crack resistance of the concrete with the added silica mortar.

[0025] The silane coupling agent KH-550 on the surface of nano-silica can cross-link with the hydroxyethyl cellulose ether on the surface of hollow glass microspheres, further improving the cross-linking network support effect of nano-silica and hollow glass microspheres. Combined with the dispersion and bonding of silica mortar, the silica mortar not only has good dispersibility and stability, but also the concrete added with silica mortar has higher compressive strength and better crack resistance, as well as better anti-settling and fluidity.

[0026] In a second aspect, the present application provides a method for preparing a modified silica mortar, which adopts the following technical solution: A method for preparing modified silica mortar comprises the following steps: S1, mixing silica ash and cellulose fiber to obtain a primary mixture; S2. Mixing the sulfamate water reducer with water to obtain a mixture; S3. Mix the primary mixed material and the mixed material and stir them evenly, and then defoam to obtain silica ash slurry.

[0027] By adopting the above technical solution, the high specific surface area of ​​silica ash facilitates the adsorption of cellulose fibers, and the initially formed dispersion system lays the foundation for subsequent mixing. If the mixing time is insufficient, the cellulose fibers are prone to agglomeration, resulting in uneven internal structure of the material, while excessive dry mixing may cause fiber wear and weaken its stabilizing effect. After uniform mixing, defoaming can reduce the bubbles introduced during the stirring process, so that the silica ash slurry has the advantages of uniform texture and stable performance. When the silica ash slurry is added to concrete, the concrete has the advantages of high strength, good crack resistance, good fluidity and good anti-settling properties.

[0028] Preferably, the stirring speed of the mixing in S2 is 800-1200 rpm, the stirring time in S3 is 3-5 min, and the standing defoaming time is 3-5 min.

[0029] By adopting the above technical solution, the speed of high-speed stirring is limited, which facilitates the rapid dispersion of water reducer molecules, fully ionizes the sulfonic acid groups, enhances its dispersibility on cement particles, forms a homogeneous solution, improves the fluidity of silica ash slurry, limits the stirring time, and avoids premature hydration reaction due to excessive stirring time.

[0030] In summary, this application has the following beneficial effects: 1. Silica fume, aminosulfonate water-reducing agent and cellulose fiber are combined. The hydrophilicity of silica fume is utilized to facilitate cross-linking with the hydroxyl groups in cellulose fiber, forming a three-dimensional cross-linked network to anchor the silica fume, so that the silica fume slurry is evenly dispersed in the cement binder while having good bonding stability, thereby improving the strength and crack resistance of the concrete added with silica fume slurry; the amino and sulfonic acid groups in the aminosulfonate water-reducing agent are easy to attract and connect with the hydroxyl groups of cellulose fiber, and the cellulose fiber increases the viscosity of the slurry, while the aminosulfonate water-reducing agent is located near the cellulose fiber to improve the fluidity of the silica fume slurry, thereby balancing the fluidity and anti-settling properties of the silica fume slurry.

[0031] 2. The melting point of cetearyl alcohol polyether-25 is lower than 50°C. During the hydration process of concrete, the temperature can reach the melting point of cetearyl alcohol polyether-25. Its hot melt can fill the internal structural gaps of concrete, improve the density of concrete structure, and thus improve the crack resistance and strength of concrete with added silica mortar. DETAILED DESCRIPTION

[0032] The present application is further described in detail below with reference to the embodiments.

[0033] Preparation example of modified cellulose fiber The following raw materials are all commercially available.

[0034] Preparation Example 1: Modified cellulose fiber was prepared by the following method: 0.12 kg of polyvinyl alcohol-1799 solution is evenly sprayed on the surface of 1 kg of cellulose fiber, and then 0.08 kg of cystine is added. The mass fraction of the polyvinyl alcohol-1799 solution is 1%, the solvent is hot water at a temperature of 95°C, and the cystine is added at a rate of 60 g / min. During the addition process, the cellulose fiber is continuously stirred at a speed of 120 r / min. After uniform mixing, the cellulose fiber is cooled and dispersed so that the cellulose fiber does not stick to each other and agglomerate, thereby obtaining modified cellulose fiber; the average length of the modified cellulose fiber is 100 μm and the average diameter is 20 nm.

[0035] Preparation Example 2: This preparation example differs from Preparation Example 1 in that: 0.1 kg of polyvinyl alcohol-1799 solution is evenly sprayed on the surface of 1 kg of cellulose fiber, and then 0.1 kg of cystine is added. The mass fraction of the polyvinyl alcohol-1799 solution is 1%, the solvent is hot water at a temperature of 95°C, and the cystine is added at a rate of 60 g / min. During the addition process, the cellulose fiber is continuously stirred at a speed of 120 r / min. After uniform mixing, the cellulose fiber is cooled and dispersed so that the cellulose fiber does not stick to each other and agglomerate, thereby obtaining modified cellulose fiber; the average length of the modified cellulose fiber is 200 μm and the average diameter is 30 nm.

[0036] Preparation Example 3: This preparation example differs from Preparation Example 1 in that: 0.15 kg of polyvinyl alcohol-1799 solution was evenly sprayed on the surface of 1 kg of cellulose fiber, and then 0.05 kg of cystine was added. The mass fraction of the polyvinyl alcohol-1799 solution was 1%, the solvent was hot water at a temperature of 95°C, and the cystine was added at a rate of 60 g / min. During the addition process, the cellulose fiber was continuously stirred at a speed of 120 r / min. After uniform mixing, the cellulose fiber was cooled and dispersed so that the cellulose fiber did not stick to each other and agglomerate, thereby obtaining modified cellulose fiber; the average length of the modified cellulose fiber was 50 μm and the average diameter was 10 nm.

[0037] Preparation example of pretreated silica fume The following raw materials are all commercially available.

[0038] Preparation Example 4: Pretreated silica fume is prepared by the following method: 0.08 kg of cetearyl alcohol polyether-25 melt is evenly sprayed on the surface of 1 kg of silica fume particles, and then 0.12 kg of magnesium oxide powder is added. The average particle size of the silica fume particles is 3 μm. The cetearyl alcohol polyether-25 melt is prepared by heating cetearyl alcohol polyether-25 to 50°C and completely melting it. The average particle size of the magnesium oxide powder is 200 nm. The addition rate of the magnesium oxide powder is 60 g / min. During the addition process, the silica fume particles are continuously stirred at a speed of 120 r / min. After mixing evenly, they are cooled and dispersed until the silica fume does not stick to each other and agglomerate to obtain the finished pretreated silica fume. The average particle size of the pretreated silica fume is less than 5 μm.

[0039] Preparation Example 5: This preparation example differs from Preparation Example 4 in that: 0.1 kg of cetearyl alcohol polyether-25 melt is evenly sprayed on the surface of 1 kg of silica fume particles, and then 0.1 kg of magnesium oxide powder is added. The average particle size of the silica fume particles is 1 μm. The cetearyl alcohol polyether-25 melt is prepared by heating cetearyl alcohol polyether-25 to 50°C and completely melting it. The average particle size of the magnesium oxide powder is 100 nm, and the addition rate of the magnesium oxide powder is 60 g / min. During the addition process, the silica fume particles are continuously stirred at a speed of 120 r / min. After mixing evenly, the silica fume is cooled and dispersed until the silica fume does not stick to each other and agglomerate to obtain a finished product of pretreated silica fume. The average particle size of the pretreated silica fume is less than 3 μm.

[0040] Preparation Example 6: This preparation example differs from Preparation Example 4 in that: 0.05 kg of cetearyl alcohol polyether-25 melt is evenly sprayed on the surface of 1 kg of silica fume particles, and then 0.15 kg of magnesium oxide powder is added. The average particle size of the silica fume particles is 5 μm. The cetearyl alcohol polyether-25 melt is prepared by heating cetearyl alcohol polyether-25 to 50°C and completely melting it. The average particle size of the magnesium oxide powder is 100 nm, and the addition rate of the magnesium oxide powder is 60 g / min. During the addition process, the silica fume particles are continuously stirred at a speed of 120 r / min. After mixing evenly, the silica fume particles are cooled and dispersed until the silica fume does not stick to each other and agglomerate to obtain the finished pretreated silica fume. The average particle size of the pretreated silica fume is less than 8 μm.

[0041] Preparation example of filled particles The following raw materials are all commercially available.

[0042] Preparation Example 7: Filled particles are prepared by the following method: 0.4 kg of silane coupling agent KH-550 was evenly sprayed into 1 kg of nano-silica and dispersed evenly to obtain modified nano-silica; 1 kg of hollow glass microspheres are immersed in 10 kg of sodium hydroxide solution, ultrasonically dispersed at 20 kHz for 10 minutes, and then the hollow glass microspheres are separated by filtration to obtain alkali-treated hollow glass microspheres; 12 kg of hydroxyethyl cellulose ether solution is added to the alkali-treated hollow glass microspheres, and then the temperature is raised to 85° C. and stirred for 30 minutes, with the hydroxyethyl cellulose ether solution continuously replenished during the stirring process, wherein the mass fraction of the hydroxyethyl cellulose ether solution is 2%, the solvent is water, and the stirring speed is 200 r / min; then the alkali-treated hollow glass microspheres are separated by filtration, and the alkali-treated hollow glass microspheres are dried and dispersed until the alkali-treated hollow glass microspheres do not stick to each other and agglomerate to obtain modified hollow glass microspheres; 1 kg of modified nano-silica and 1 kg of modified hollow glass microspheres were weighed and mixed evenly to obtain filling particles.

[0043] Preparation Example 8: This preparation example differs from Preparation Example 7 in that: 0.3 kg of silane coupling agent KH-550 was evenly sprayed into 1 kg of nano-silica and dispersed evenly to obtain modified nano-silica; 1 kg of hollow glass microspheres were immersed in 8 kg of sodium hydroxide solution, ultrasonically dispersed at 20 kHz for 10 minutes, and then the hollow glass microspheres were separated by filtration to obtain alkali-treated hollow glass microspheres; 8 kg of hydroxyethyl cellulose ether solution was added to the alkali-treated hollow glass microspheres, and then the temperature was raised to 85° C. and stirred for 30 minutes. The hydroxyethyl cellulose ether solution was continuously replenished during the stirring process at a stirring speed of 200 r / min, and then the alkali-treated hollow glass microspheres were separated by filtration, and dried and dispersed until the alkali-treated hollow glass microspheres did not stick to each other and agglomerate to obtain modified hollow glass microspheres; 1 kg of modified nano-silica and 0.5 kg of modified hollow glass microspheres were weighed and mixed evenly to obtain filling particles.

[0044] Preparation Example 9: This preparation example differs from Preparation Example 7 in that: 0.5 kg of silane coupling agent KH-550 was evenly sprayed into 1 kg of nano-silica and dispersed evenly to obtain modified nano-silica; 1 kg of hollow glass microspheres were immersed in 12 kg of sodium hydroxide solution, ultrasonically dispersed at 20 kHz for 10 minutes, and then the hollow glass microspheres were separated by filtration to obtain alkali-treated hollow glass microspheres; 15 kg of hydroxyethyl cellulose ether solution was added to the alkali-treated hollow glass microspheres, and then the temperature was raised to 85° C. and stirred for 30 minutes. The hydroxyethyl cellulose ether solution was continuously replenished during the stirring process at a stirring speed of 200 r / min, and then the alkali-treated hollow glass microspheres were separated by filtration, and the alkali-treated hollow glass microspheres were dried and dispersed until the alkali-treated hollow glass microspheres did not stick to each other and agglomerate to obtain modified hollow glass microspheres; 1 kg of modified nano-silica and 1.2 kg of modified hollow glass microspheres were weighed and mixed evenly to obtain filling particles. Example

[0045] The following raw materials are all commercially available.

[0046] Example 1: A modified silica mortar: Silica fume 40kg, aminosulfonate water reducer 0.1kg, cellulose fiber 0.1kg, water 59.8kg; silica fume specific surface area ≥15000m 2 / kg, SiO2 content ≥92%; the aminosulfonate water reducer has a molecular weight of 4000 and contains ≥80% sulfonic acid groups; the silica fume is the pretreated silica fume prepared in Preparation Example 4; the cellulose fiber is modified cellulose fiber, and the modified cellulose fiber is the modified cellulose fiber prepared in Preparation Example 1; The preparation method is as follows: S1, mixing silica ash and cellulose fiber for 4 minutes to obtain a primary mixture; S2. Mixing the aminosulfonate water reducer with water, stirring at a speed of 1000 r / min to obtain a mixture; S3. Mix the primary mixture and the mixed material, stir at a speed of 1000 r / min for 4 minutes, mix them evenly, and let them stand for 4 minutes to defoam, to obtain silica ash slurry.

[0047] Example 2: This example differs from Example 1 in that: 38kg silica fume, 0.08kg sulfamate water reducer, 0.08kg cellulose fiber, 57kg water; silica fume specific surface area ≥ 15000m 2 / kg, SiO2 content ≥92%; the molecular weight of the aminosulfonate water reducer is 2000, and the sulfonic acid group content is ≥80%; the silica fume is the pretreated silica fume prepared in Preparation Example 5; the cellulose fiber is modified cellulose fiber, and the modified cellulose fiber is the modified cellulose fiber prepared in Preparation Example 2; The preparation method is as follows: S1, mixing silica ash and cellulose fiber for 3 minutes, mixing them evenly to obtain a primary mixture; S2. Mixing the aminosulfonate water reducer with water, stirring at a speed of 800 r / min to obtain a mixture; S3. Mix the primary mixture and the mixed material, stir at a speed of 800 r / min for 3 minutes, mix them evenly, and let them stand for 3 minutes to defoam, to obtain silica ash slurry.

[0048] Example 3: This example differs from Example 1 in that: Silica fume 42kg, aminosulfonate water reducer 0.12kg, cellulose fiber 0.12kg, water 63kg; silica fume specific surface area ≥ 15000m 2 / kg, SiO2 content ≥92%; the aminosulfonate water reducer has a molecular weight of 5000 and contains ≥80% sulfonic acid groups; the silica fume is the pretreated silica fume prepared in Preparation Example 6; the cellulose fiber is modified cellulose fiber, and the modified cellulose fiber is the modified cellulose fiber prepared in Preparation Example 3; The preparation method is as follows: S1, mixing silica ash and cellulose fiber for 5 minutes to obtain a primary mixture; S2. Mixing the sulfamate water reducer with water, stirring at a speed of 1200 r / min to obtain a mixture; S3. Mix the primary mixture and the mixed material, stir at a speed of 1200 r / min for 5 minutes, mix them evenly, and let them stand for 5 minutes to defoam, to obtain silica ash slurry.

[0049] Example 4: This example differs from Example 1 in that: 4 kg of the filler particles prepared in Preparation Example 7 were added to the silica slurry.

[0050] Example 5: This example differs from Example 4 in that: 2 kg of the filler particles prepared in Preparation Example 8 were added to the silica slurry.

[0051] Example 6: This example differs from Example 4 in that: 6 kg of the filler particles prepared in Preparation Example 9 were added to the silica slurry.

[0052] Example 7: This example differs from Example 1 in that: During the preparation of the modified cellulose fiber, the polyvinyl alcohol-1799 solution was replaced by the polyvinyl alcohol-1788 aqueous solution of equal mass, the water temperature of the polyvinyl alcohol-1788 aqueous solution was room temperature 25° C., and the mass fraction was 1%.

[0053] Example 8: This example differs from Example 1 in that: During the preparation of the modified cellulose fibers, no cystine was added.

[0054] Example 9: This example differs from Example 1 in that: The silica fume is commercially available silica fume without the addition of magnesium oxide micropowder and ceteareth-25.

[0055] Example 10: This example differs from Example 7 in that: The filling particles are replaced by modified nano-silica with the same mass of nano-silica.

[0056] Example 11: This example differs from Example 7 in that: The filling particles are hollow glass microspheres of equal mass replacing the modified hollow glass microspheres.

[0057] Example 12: This example differs from Example 7 in that: No hydroxyethyl cellulose ether solution was added during the preparation of the modified hollow glass microspheres in the filling particles.

[0058] Comparative Example Comparative Example 1: The difference between this comparative example and Example 1 is that: No cellulose fibers are added to the raw materials.

[0059] Performance testing 1. Strength detection Silica ash slurry was prepared by the methods of Examples 1-12 and Comparative Example 1 respectively; Weigh 280kg of cement, 900kg of crushed stone, 700kg of sand, 125kg of silica mortar, 50kg of water, and 3.0kg of aminosulfonic acid water reducer, mix and stir evenly, pour and cure to obtain concrete; the cement is silicate cement with a P.O4 of 2.5, the crushed stone is crushed stone with a continuous particle size of 5-20mm, and the sand is medium sand in Zone II, with an apparent density of 2660kg / m 3 , the silica ash slurries are the silica ash slurries prepared in the above examples or comparative examples respectively; Refer to GB / T50081 to test the 28d compressive strength and record the data.

[0060] 2. Crack resistance test Silica ash slurry was prepared by the methods of Examples 1-12 and Comparative Example 1 respectively; Weigh 280kg of cement, 900kg of crushed stone, 700kg of sand, 125kg of silica mortar, 50kg of water, and 3.0kg of aminosulfonic acid water reducer, mix and stir evenly, pour and cure to obtain concrete; the cement is silicate cement with a P.O4 of 2.5, the crushed stone is crushed stone with a continuous particle size of 5-20mm, and the sand is medium sand in Zone II, with an apparent density of 2660kg / m 3 , the silica ash slurries are the silica ash slurries prepared in the above examples or comparative examples respectively; Prepare test blocks according to GB / T50081 and calculate the total cracking area per unit area after 24 hours of concrete pouring.

[0061] 3. Liquidity test Silica ash slurry was prepared by the methods of Examples 1-7 and 9 respectively; Weigh 280kg of cement, 900kg of crushed stone, 700kg of sand, 125kg of silica mortar, 50kg of water, and 3.0kg of aminosulfonic acid water reducer, mix and stir evenly, pour and cure to obtain concrete; the cement is silicate cement with a P.O4 of 2.5, the crushed stone is crushed stone with a continuous particle size of 5-20mm, and the sand is medium sand in Zone II, with an apparent density of 2660kg / m 3 , the silica ash slurries are the silica ash slurries prepared in the above examples or comparative examples respectively; Refer to GB / T50080 to test the slump. The larger the slump, the better the fluidity. Record the slump data.

[0062] 4. Anti-settling test Silica ash slurries were prepared using the methods of Examples 1-6, 8 and Comparative Example 1 respectively; the sedimentation rate was calculated and the data was recorded.

[0063] Table 1 Performance test table It can be seen from Examples 1-3 and Table 1 that the silica ash mortar prepared in the present application has good compressive strength and good crack resistance when added to concrete, and has good fluidity and good anti-settling property.

[0064] From Example 1 and Examples 4-6 and Table 1, it can be seen that after adding the filling particles, the strength of the filling particles and the cross-linking effect of the filling particles and the silica mortar are utilized to further improve the strength and crack resistance of the concrete, and the concrete is less likely to have settlement problems, and a certain fluidity can be guaranteed.

[0065] Combining Example 1 and Examples 7-9 and Table 1, it can be seen that in the preparation process of the modified cellulose fiber in Example 7, the polyvinyl alcohol-1788 aqueous solution of equal mass is used to replace the polyvinyl alcohol-1799 solution. Compared with Example 1, the compressive strength of Example 7 is lower than that of Example 1, the cracking area is larger than that of Example 1, and the slump is lower than that of Example 1. This shows that polyvinyl alcohol-1788 has a low degree of hydrolysis, good water solubility, and produces viscosity when dissolved, which easily affects fluidity, thereby affecting the slump, and affecting the role of mixing water in the hydration process, thereby affecting the strength and crack resistance of the concrete.

[0066] During the preparation of the modified cellulose fiber of Example 8, cystine was not added. Compared with Example 1, the compressive strength of Example 8 was lower than that of Example 1, the cracking area was larger than that of Example 1, and the sedimentation rate was greater than that of Example 1. This indicates that the amino and carboxyl groups in cystine make the surface of the modified cellulose fiber attract the silica mortar to hydrogen bonds, thereby improving the strength and crack resistance of the concrete with added silica mortar. In addition, the sulfur element in the cystine on the surface of the modified cellulose fiber further binds and bonds with the silicon element in the silica mortar, thereby improving the stability of the silica mortar on the surface of the modified cellulose fiber, ensuring that the silica mortar has good fluidity and good anti-settling properties.

[0067] The silica fume in Example 9 is commercially available silica fume, without the addition of magnesium oxide micropowder and cetearyl alcohol polyether-25. Compared with Example 1, the compressive strength of Example 9 is lower than that of Example 1, the cracking area is larger than that of Example 1, and the slump is lower than that of Example 1. This indicates that the combination of magnesium oxide micropowder and cetearyl alcohol polyether-25 can reduce the friction between silica fume particles and improve the fluidity of silica ash mortar, and the addition of magnesium oxide micropowder and the bonding effect of the compound of cetearyl alcohol polyether-25 and silica mortar further improve the strength and crack resistance of concrete with added silica mortar.

[0068] Combining Example 4 and Examples 10-12 and Table 1, it can be seen that the filling particles in Example 10 replace the modified nano-silica with nano-silica of equal mass. Compared with Example 4, the compressive strength of Example 10 is lower than that of Example 4, and the crack area is larger than that of Example 4; this shows that the addition of filling particles can increase the strength of concrete with added silica mortar, and utilize its filling effect to increase the structural density and improve the crack resistance.

[0069] In Example 11, the filling particles are replaced with modified hollow glass microspheres with hollow glass microspheres of equal mass. Compared with Example 4, the compressive strength of Example 11 is lower than that of Example 4, and the crack area is larger than that of Example 4. This shows that after the surface of the hollow glass microspheres is treated with sodium hydroxide solution and hydroxyethyl cellulose ether, not only the strength of the concrete with added silica mortar can be improved, but also the crack resistance can be improved.

[0070] No hydroxyethyl cellulose ether solution was added during the preparation of the modified hollow glass microspheres in the filling particles of Example 12. Compared with Example 4, the compressive strength of Example 12 was lower than that of Example 4, and the crack area was larger than that of Example 4. This indicates that hydroxyethyl cellulose ether is more active under alkaline conditions, which improves the bonding effect between the modified hollow glass microspheres and the silica mortar. The hydroxyethyl cellulose ether molecular chain can form a flexible cross-linked network after the concrete is cured, which cooperates with the bonding effect between the silica mortar and the concrete, further improving the compressive strength and crack resistance of the concrete with the silica mortar added.

[0071] Combining Example 1 and Comparative Example 1 and Table 1, it can be seen that no cellulose fiber is added to the raw materials of Comparative Example 1. Compared with Example 1, the compressive strength of Comparative Example 1 is lower than that of Example 1, the cracking area is larger than that of Example 1, and the sedimentation rate is greater than that of Example 1; this shows that the addition of cellulose fiber can improve the stability of the silica ash mortar, thereby reducing the sedimentation rate and ensuring the strength and crack resistance of the silica ash mortar.

[0072] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A modified silica mortar, characterized in that: The method comprises the following raw materials in parts by weight: 38-42 parts of silica fume, 0.08-0.12 parts of aminosulfonate water reducer, 0.18-0.22 parts of cellulose fiber, and 57-63 parts of water; Silica fume specific surface area ≥15000 m² / kg.

2. The modified silica mortar according to claim 1, characterized in that: The cellulose fibers are modified cellulose fibers with an average length of 50-200 μm and an average diameter of 10-30 nm.

3. The modified silica mortar according to claim 2, characterized in that: The modified cellulose fiber is prepared from cellulose fiber filaments, polyvinyl alcohol-1799 solution and cystine in a mass ratio of 1:0.1-0.15:0.05-0.

1.

4. The modified silica mortar according to claim 1, characterized in that: The aminosulfonate water reducer has a molecular weight of 2000-5000 and contains sulfonic acid groups ≥80%.

5. The modified silica mortar according to claim 1, characterized in that: The silica fume is pretreated silica fume, which is prepared by loading silica fume particles with a cetearyl alcohol polyether-25 melt and then bonding them with magnesium oxide micropowder. The mass ratio of silica fume particles, cetearyl alcohol polyether-25 melt and magnesium oxide micropowder is 1:0.05-0.1:0.1-0.

15.

6. The modified silica mortar according to claim 1, characterized in that: The silica mortar further comprises 2-6 parts of filling particles; the filling particles are composed of modified nano-silica and modified hollow glass microspheres in a mass ratio of 1:0.5-1.

2.

7. The modified silica mortar according to claim 6, characterized in that: The modified nano-silica is prepared from nano-silica and silane coupling agent KH-550 in a mass ratio of 1:0.3-0.

5.

8. The modified silica mortar according to claim 6, characterized in that: The modified hollow glass microspheres are prepared by treating hollow glass microspheres with a sodium hydroxide solution, then adding a hydroxyethyl cellulose ether solution, and heating and stirring. The mass ratio of the hollow glass microspheres, the sodium hydroxide solution and the hydroxyethyl cellulose ether solution is 1:8-12:8-15.

9. The method for preparing a modified silica mortar according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, mixing silica ash and cellulose fiber to obtain a primary mixture; S2. Mixing the sulfamate water reducer with water to obtain a mixture; S3. Mix the primary mixed material and the mixed material and stir them evenly, and then defoam to obtain silica ash slurry.

10. The method for preparing a modified silica mortar according to claim 9, characterized in that: The stirring speed of the mixing in S2 is 800-1200 rpm, the stirring time in S3 is 3-5 min, and the standing and defoaming time is 3-5 min.

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