阅读说明：本技术 一种抗冻水泥的制备方法 (Preparation method of anti-freezing cement ) 是由 钱丽艳 于 2019-12-02 设计创作，主要内容包括：本发明公开了一种抗冻水泥的制备方法,具体方法如下：1)浓硫酸置于冰水浴中,加入纳米二氧化硅进行搅拌,然后加入硝酸钠、高锰酸钾,反应后再加入双氧水,制得改性纳米二氧化硅；2)改性纳米二氧化硅分散液加入丙烯酸,振荡后加入玻璃纤维、过硫酸钾、盐酸,制得改性纳米二氧化硅复合纤维粉；3)剩余原料加入到改性纳米二氧化硅复合纤维粉分散液中,加水搅拌后制得水泥基材；4)水泥基材放入容器中,搅拌后注入氮气,将表面活性剂溶液注入容器中,继续搅拌；5)经过处理的水泥基材养护后进行干燥即可制得。该水泥内部结构紧密,孔隙率低,具有很好的承载能力和断裂韧度,具有优异的抗冻性,可以很好的满足严寒地区的施工需求。(The invention discloses a preparation method of antifreeze cement, which comprises the following steps: 1) placing concentrated sulfuric acid in an ice-water bath, adding nano-silica, stirring, then adding sodium nitrate and potassium permanganate, reacting, and then adding hydrogen peroxide to prepare modified nano-silica; 2) adding acrylic acid into the modified nano-silica dispersion liquid, oscillating, and adding glass fiber, potassium persulfate and hydrochloric acid to prepare modified nano-silica composite fiber powder; 3) adding the rest raw materials into the modified nano silicon dioxide composite fiber powder dispersion liquid, adding water and stirring to obtain a cement base material; 4) putting the cement base material into a container, stirring, injecting nitrogen, injecting a surfactant solution into the container, and continuously stirring; 5) curing the treated cement base material, and drying to obtain the cement base material. The cement has the advantages of compact internal structure, low porosity, good bearing capacity and fracture toughness, excellent freezing resistance and capability of well meeting the construction requirement of severe cold areas.)

1. The preparation method of the antifreeze cement is characterized by comprising the following steps:

1) taking 80-130 parts of concentrated sulfuric acid, placing in an ice water bath, cooling to 0-5 ℃, then adding 3-5 parts of nano silicon dioxide, stirring at the rotation speed of 100-130r/min for 20-30min, then adding 1-1.5 parts of sodium nitrate and 8-12 parts of potassium permanganate, stirring and reacting for 50-70min at the rotating speed of 50-80r/min, then heating to 30-40 ℃, continuously stirring and reacting for 25-45min at the rotating speed of 40-60r/min, then heating to 80-100 ℃, adding 3-4 parts of hydrogen peroxide, reacting at constant temperature for 30-40min, filtering after the reaction is finished, washing with barium chloride and deionized water until no white precipitate is generated, then drying the mixture in an oven at the temperature of between 50 and 60 ℃ to constant weight to prepare modified nano silicon dioxide;

2) adding modified nano-silica into 40-60 parts of distilled water, oscillating and dispersing for 15-25min under 300-350W ultrasonic wave to prepare modified nano-silica dispersion liquid, then adding 5-10 parts of acrylic acid, oscillating and dispersing for 40-60min under 200-300W ultrasonic wave, then adding 4-7 parts of ground glass fiber, continuing oscillating and dispersing for 30-50min, then adding 0.1-0.2 part of potassium persulfate and 5-10 parts of hydrochloric acid, heating to 60-70 ℃, reacting at constant temperature for 3-5h, alternately washing the product to be neutral by using absolute ethyl alcohol and distilled water, drying in an oven at 50-60 ℃ to constant weight, and carrying out superfine grinding to prepare modified nano-silica composite fiber powder;

3) adding modified nano-silica composite fiber powder into 50-100 parts of water, oscillating and dispersing for 1-2 hours under 300-plus-400W ultrasonic wave to prepare modified nano-silica composite fiber powder dispersion liquid, then taking 70-100 parts of cement clinker, 4-6 parts of fly ash, 2-3 parts of gypsum powder and 3-4 parts of slag powder, mixing, adding 300 parts of 150-plus-water, adding the modified nano-silica composite fiber powder dispersion liquid, and stirring for 30-40min at the rotating speed of 150-plus-water 300r/min to prepare a cement base material;

4) transferring the cement base material into a closed container, carrying out oscillation stirring at the rotating speed of 300-fold sand-crushing at 500r/min, injecting nitrogen into the container for preheating for 30-40min, then injecting the atomized surfactant solution into the container while injecting the nitrogen, continuing to inject the nitrogen for 20-30min after the surfactant solution is completely injected into the container, and reducing the rotating speed to 200-fold sand-crushing at 300r/min, and continuing oscillation stirring;

5) and curing the treated cement base material by steam, drying, and screening to obtain the finished cement.

2. The method for preparing antifreeze cement of claim 1, wherein in step 1), the concentrated sulfuric acid has a concentration of 70-80%; the concentration of the hydrogen peroxide is 4-10%.

3. The method of claim 1, wherein in step 2), the milled glass fibers have an average diameter of 3 to 10 μm; the average diameter of the modified nano silicon dioxide composite fiber powder is 10-20 um.

4. The method of claim 1, wherein in step 3), the cement clinker is ground from portland cement clinker and has a surface area of more than 400m²Per kg; the fly ash is prepared by grinding the fly ash into powder with the specific surface area of more than 350m²A/kg of powdery material; the gypsum powder is prepared by grinding gypsum powder to specific surface area of more than 380m²A/kg of powdery material; the slag powder is prepared from slagGrinding to specific surface area of more than 370m²A/kg of pulverulent material.

5. The method for preparing antifreeze cement as claimed in claim 1, wherein the temperature of the injected nitrogen in step 4) is 120-180 ℃; the injection pressure of the nitrogen is 10-15 MPa; the injection pressure of the surfactant solution is 5-10 MPa; the surfactant solution is prepared by adding sodium dodecyl benzene sulfonate into deionized water, stirring and dissolving, wherein the addition amount of the sodium dodecyl benzene sulfonate is 2-5% of the weight of the deionized water; the atomization method of the surfactant solution is any one of pressure atomization, rotary disc atomization and sound wave atomization.

6. The method for preparing a frost-resistant cement according to claim 1, wherein in step 5), said steam curing is performed by subjecting the cement to air with a carbon dioxide concentration of 20-40% by volume; the steam curing temperature is 100-; the drying temperature is 70-80 ℃, and the drying time is 4-7 h; the screening is to grind the cement base material to pass through a hole screen with the hole diameter of 0.05-0.1mm, and the screen residue is less than 2-5%.

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to a preparation method of antifreeze cement.

Background

In areas with higher latitude or altitude, the cement can be frozen in cold weather and freezing environment, thereby greatly reducing the performance of the cement and directly influencing the strength of the building. In order to prevent cement from being frozen at low temperature, people usually adopt antifreezing methods such as adding an antifreezing agent or steam curing, heat preservation and the like, but the latter method is not suitable for large-area application due to complex construction and low efficiency. At present, the cement antifreezing agent is mainly added into common cement in the construction process in the building industry, the method produces a certain positive effect, but because the antifreezing agent is generally only a few percent of the weight of the cement, the phenomenon of uneven stirring often exists, the antifreezing degree is not high, the antifreezing effect is uneven, the construction quality is affected, and further a certain economic loss is caused, and in addition, the addition amount of the antifreezing agent needs to be accurately controlled in the construction process, so that the construction is inconvenient.

Disclosure of Invention

The invention aims to provide a preparation method of antifreeze cement aiming at the existing problems.

The invention is realized by the following technical scheme:

a preparation method of antifreeze cement comprises the following steps:

1) taking 80-130 parts of concentrated sulfuric acid, placing in an ice water bath, cooling to 0-5 ℃, then adding 3-5 parts of nano silicon dioxide, stirring at the rotation speed of 100-130r/min for 20-30min, then adding 1-1.5 parts of sodium nitrate and 8-12 parts of potassium permanganate, stirring and reacting for 50-70min at the rotating speed of 50-80r/min, then heating to 30-40 ℃, continuously stirring and reacting for 25-45min at the rotating speed of 40-60r/min, then heating to 80-100 ℃, adding 3-4 parts of hydrogen peroxide, reacting at constant temperature for 30-40min, filtering after the reaction is finished, washing with barium chloride and deionized water until no white precipitate is generated, then drying the mixture in an oven at the temperature of between 50 and 60 ℃ to constant weight to prepare modified nano silicon dioxide;

2) adding modified nano-silica into 40-60 parts of distilled water, oscillating and dispersing for 15-25min under 300-350W ultrasonic wave to prepare modified nano-silica dispersion liquid, then adding 5-10 parts of acrylic acid, oscillating and dispersing for 40-60min under 200-300W ultrasonic wave, then adding 4-7 parts of ground glass fiber, continuing oscillating and dispersing for 30-50min, then adding 0.1-0.2 part of potassium persulfate and 5-10 parts of hydrochloric acid, heating to 60-70 ℃, reacting at constant temperature for 3-5h, alternately washing the product to be neutral by using absolute ethyl alcohol and distilled water, drying in an oven at 50-60 ℃ to constant weight, and carrying out superfine grinding to prepare modified nano-silica composite fiber powder;

3) adding modified nano-silica composite fiber powder into 50-100 parts of water, oscillating and dispersing for 1-2 hours under 300-plus-400W ultrasonic wave to prepare modified nano-silica composite fiber powder dispersion liquid, then taking 70-100 parts of cement clinker, 4-6 parts of fly ash, 2-3 parts of gypsum powder and 3-4 parts of slag powder, mixing, adding 300 parts of 150-plus-water, adding the modified nano-silica composite fiber powder dispersion liquid, and stirring for 30-40min at the rotating speed of 150-plus-water 300r/min to prepare a cement base material;

4) transferring the cement base material into a closed container, carrying out oscillation stirring at the rotating speed of 300-fold sand-crushing at 500r/min, injecting nitrogen into the container for preheating for 30-40min, then injecting the atomized surfactant solution into the container while injecting the nitrogen, continuing to inject the nitrogen for 20-30min after the surfactant solution is completely injected into the container, and reducing the rotating speed to 200-fold sand-crushing at 300r/min, and continuing oscillation stirring;

5) and curing the treated cement base material by steam, drying, and screening to obtain the finished cement.

Preferably, the preparation method of the antifreeze cement comprises the step 1), wherein the concentration of the concentrated sulfuric acid is 70-80%; the concentration of the hydrogen peroxide is 4-10%.

Preferably, the preparation method of the antifreeze cement comprises the step 2), wherein the average diameter of the ground glass fiber is 3-10 um; the average diameter of the modified nano silicon dioxide composite fiber powder is 10-20 um.

Preferably, the method for preparing the antifreeze cement comprises the step 3), wherein the cement clinker is formed by grinding the silicate cement clinker, and the surface area of the cement clinker is more than 400m²Per kg; the fly ash is prepared by grinding the fly ash into powder with the specific surface area of more than 350m²A/kg of powdery material; the gypsum powder is prepared by grinding gypsum powder to specific surface area of more than 380m²A/kg of powdery material; the slag powder is prepared by grinding slag powder to specific surface area larger than 370m²A/kg of pulverulent material.

Preferably, the preparation method of the antifreeze cement, wherein in the step 4), the temperature of the injected nitrogen is 120-180 ℃; the injection pressure of the nitrogen is 10-15 MPa; the injection pressure of the surfactant solution is 5-10 MPa; the surfactant solution is prepared by adding sodium dodecyl benzene sulfonate into deionized water, stirring and dissolving, wherein the addition amount of the sodium dodecyl benzene sulfonate is 2-5% of the weight of the deionized water; the atomization method of the surfactant solution is any one of pressure atomization, rotary disc atomization and sound wave atomization.

Preferably, in the step 5), the steam curing is to cure the cement in an air condition with the volume concentration of carbon dioxide of 20-40%; the steam curing temperature is 100-; the drying temperature is 70-80 ℃, and the drying time is 4-7 h; the screening is to grind the cement base material to pass through a hole screen with the hole diameter of 0.05-0.1mm, and the screen residue is less than 2-5%.

Compared with the prior art, the invention has the following advantages: according to the cement prepared by the method, firstly, nano silicon dioxide is subjected to oxidation treatment, the number of oxygen-containing functional groups on the surface of the nano silicon dioxide is increased, and the reaction activity of the nano silicon dioxide is improved; secondly, under the action of ultrasonic wave, the modified nano silicon dioxide and the glass fiber are uniformly dispersed in water and react with macromolecules under the action of an initiator, thereby leading the modified nano silicon dioxide and the glass fiber to be respectively connected with the macromolecule of polyacrylic acid, thereby forming the modified nano silicon dioxide composite fiber, the composite fiber can be well filled in the micropores of a cement substrate after being subjected to superfine grinding, the generation and the expansion of microcracks are inhibited, thereby reducing the porosity of the cement, making the cement structure compact, thereby improving the freezing resistance thereof, and, because the glass fiber has the characteristic of high mechanical strength, the composite fiber can effectively improve the bearing capacity and the fracture toughness of the cement, but also can reduce the loss of the compressive strength of the cement in a low-temperature environment, so that the cement still has good mechanical properties in the low-temperature environment; thirdly, adding the modified nano-silica composite fiber powder into distilled water for ultrasonic oscillation dispersion, so that the composite fiber powder can be uniformly dispersed in the cement base material as much as possible, then placing the prepared cement base material into a container for stirring, introducing nitrogen for preheating, so that the cement base material can be uniformly heated, atomizing a surfactant and injecting into the container, wherein the surfactant can be fully contacted with the cement base material under the carrying of high-speed nitrogen flow, so that the surface tension of the cement base material is reduced, and the permeability of the modified nano-silica composite fiber powder in the cement base material is improved; finally, steam curing is carried out after the cement base material is cast, carbon dioxide contained in steam can enter pores of the cement base material and reacts with hydrate calcium hydroxide of the cement base material to generate calcium carbonate, and the filled pores can further reduce the porosity of the cement, so that the strength of the cement is enhanced. The cement has the advantages of compact internal structure, low porosity, good bearing capacity and fracture toughness, excellent freezing resistance and capability of well meeting the construction requirement of severe cold areas.

Detailed Description

The present invention will be described below with reference to specific embodiments.