阅读说明：本技术 一种无石膏硅酸盐水泥的制备方法 (Preparation method of gypsum-free portland cement ) 是由 刘彤 刘爽 张鹏宇 滕藤 王建恒 刘凤东 白锡庆 王冬梅 于 2019-11-12 设计创作，主要内容包括：本发明提供了一种无石膏硅酸盐水泥的制备方法,包括用混合气流对水泥熟料表面进行接触法预处理的过程；所述混合气流至少包括水蒸气气流。该方法改变通用硅酸盐水泥掺加石膏调节水泥凝结的固有方式,采用表面接触法对硅酸盐水泥熟料颗粒细粉进行预处理,使水泥熟料矿物中铝酸三钙颗粒表面生成并沉积预处理产物；经此方法处理的水泥熟料,与适量混合材料配制成无石膏硅酸盐水泥,加水拌合时,经预处理的熟料颗粒表面沉积的预处理产物可有效阻滞水泥加水拌合后初期的水化速度,实现对水泥初期凝结速率的有效调节；以此方法制备得到的无石膏硅酸盐水泥,水化热放热速率、蓄热量均明显低于普通硅酸盐水泥。(The invention provides a preparation method of gypsum-free portland cement, which comprises the steps of carrying out contact pretreatment on the surface of cement clinker by using mixed gas flow; the mixed gas stream comprises at least a water vapor gas stream. The method changes the inherent mode that the common portland cement is mixed with gypsum to adjust the cement coagulation, and adopts a surface contact method to pretreat the fine powder of portland cement clinker particles, so that tricalcium aluminate particles in cement clinker minerals generate and deposit a pretreated product on the surfaces; the cement clinker processed by the method is prepared into gypsum-free portland cement with a proper amount of mixed materials, when the cement clinker is mixed with water, a pretreatment product deposited on the surface of pretreated clinker particles can effectively retard the initial hydration speed of the cement after the cement is mixed with water, and the effective regulation of the initial setting rate of the cement is realized; the heat release rate and the heat storage capacity of the hydration heat of the gypsum-free portland cement prepared by the method are obviously lower than those of ordinary portland cement.)

1. A preparation method of gypsum-free portland cement is characterized by comprising the following steps: comprises the process of pretreating the surface of cement clinker by a contact method by using mixed gas flow; the mixed gas stream comprises at least a water vapor gas stream.

2. The method of claim 1, wherein the method comprises the steps of: the mixed gas flow consists of hot air and water vapor, the temperature of the mixed gas flow ranges from 100 ℃ to 200 ℃, and the water vapor accounts for 10% -100% of the volume of the mixed gas flow.

3. The method of claim 1, wherein the method comprises the steps of: before the pretreatment by the contact method, the cement clinker is levigated into fine powder particles with the specific surface area of more than or equal to 300 square meters per kilogram.

4. The method of claim 1, wherein the method comprises the steps of: the cement clinker is silicate cement clinker.

5. The method of claim 1, wherein the method comprises the steps of: the contact pretreatment may be carried out in an atmospheric or pressure vessel.

6. The method of claim 5, wherein the step of preparing the gypsum-free portland cement comprises the steps of: the pretreatment in a pressure vessel by a contact method has the treatment pressure of 0.1MPa-1.2MPa, the treatment temperature of 100 ℃ to 220 ℃ and the treatment time of 5 minutes to 85 minutes.

7. The method of claim 5, wherein the step of preparing the gypsum-free portland cement comprises the steps of: the pretreatment by the contact method is carried out in a normal pressure vessel under stirring at a treatment temperature of 100 to 170 ℃ for 2 to 18 minutes.

Technical Field

The invention belongs to the technical field of cement preparation, and particularly relates to a preparation method of gypsum-free portland cement.

Background

The cement is a solid powdery substance, has plasticity after being mixed with water, can be self-bonded into a hard whole, can be bonded with other granular materials, and can be hardened in the air and also be coagulated and hardened in the water.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides a preparation method of gypsum-free portland cement, which changes the inherent mode of regulating cement coagulation by adding gypsum into general portland cement, and adopts a surface contact method to pretreat fine powder of portland cement clinker particles so as to generate and deposit a pretreated product on the surfaces of tricalcium aluminate particles in cement clinker minerals. The cement clinker treated by the method is mixed with a proper amount of mixed materials to prepare gypsum-free portland cement. When the water is added for mixing, the pre-treatment product deposited on the surface of the pre-treated clinker particles can effectively retard the initial hydration speed of cement after being mixed with water, and the effective regulation of the initial setting rate of the cement is realized. The heat release rate and the heat storage capacity of the hydration heat of the gypsum-free portland cement prepared by the method are obviously lower than those of ordinary portland cement.

The preparation method of the gypsum-free portland cement comprises the step of pretreating the surface of cement clinker by a contact method by using mixed air flow; the mixed gas stream comprises at least a water vapor gas stream.

Further, the mixed air flow consists of hot air and water vapor, and the water vapor accounts for 10-100% of the volume of the mixed air flow.

Further, the cement clinker is silicate cement clinker.

Further, the contact pretreatment may be carried out in an atmospheric or pressure vessel.

Further, the pretreatment is carried out in a pressure vessel by a contact method under the treatment pressure of 0.1MPa-1.2MPa, the treatment temperature of 100 ℃ to 220 ℃ and the treatment time of 5 minutes to 85 minutes.

Further, the treatment temperature for the pretreatment by the contact method is 100 to 170 ℃ and the treatment time is 2 to 18 minutes under stirring in a normal pressure vessel.

The preparation method of the gypsum-free portland cement has the following beneficial effects:

(1) because the surface contact method pretreatment process directly influences tricalcium aluminate in cement clinker and effectively retards the hydration speed and the hydration process of tricalcium aluminate in cement after being mixed by adding water, the most obvious improvement of gypsum-free portland cement is that the hydration heat is obviously lower than that of general portland cement prepared by the same batch of cement clinker. Therefore, adverse effects on various concrete structures caused by release and accumulation of hydration heat can be effectively improved.

(2) The invention adopts a specific technical means to passivate the most active mineral component, namely tricalcium aluminate, in the cement clinker, so that the generation process of cement stone gel generated by cement hydration is more smooth, the internal reason of the volume change is solved to a certain degree, and the cement hydration process can be more smooth.

(3) Since the gypsum-free portland cement proposed by the present invention does not contain a gypsum component, it is expected that the present invention will be more advantageous in improving the compatibility of cement with various additives. Compared with the unstable factors brought by the original instant generation of ettringite, the rapid deposition of the surface of clinker particles, the rapid crystal transformation and the like, the mixture of the gypsum-free portland cement provided by the invention is more favorable for the retention of operability indexes (such as mortar consistency, concrete slump and the like) with time.

(4) The invention adopts surface contact pretreatment to passivate the surfaces of cement clinker particles, and achieves the effects of inhibiting the over-fast hydration and the early thickening and condensation of cement clinker at the initial stage of mixing with water through the pretreatment product generated and deposited on the surfaces of tricalcium aluminate particles. Therefore, the compatibility and affinity of the cement hydrated gel system and other added composite materials, such as polymer emulsion, various fibers, various functional materials and the like, can be improved by changing the type and the form of the contact medium and the reactable materials in the contact medium. And the chemical environment in the cement-stone gel can be improved and optimized through the change of the components of the isolating layer generated and deposited on the surface, so that the metal materials such as the steel bars and the like can be better protected.

Drawings

FIG. 1 is a heat map of the difference between the untreated clinker of examples 1-5;

FIG. 2 is a thermal map of clinker difference after treatment of example 1;

FIG. 3 is a clinker difference thermal map after the treatment of example 2;

FIG. 4 is a clinker difference thermal map after treatment in example 3;

FIG. 5 is a thermal map of clinker difference after treatment of example 4;

FIG. 6 is a thermal map of clinker difference after treatment of example 5;

FIG. 7 is a heat map of the difference between the untreated clinker of examples 6-10;

FIG. 8 is a thermal map of clinker difference after treatment of example 6;

FIG. 9 is a clinker difference thermal map after treatment of example 7;

FIG. 10 is a clinker difference thermal map after treatment of example 8;

FIG. 11 is a clinker difference thermal map after treatment of example 9;

FIG. 12 is a clinker difference thermal map after treatment of example 10;

FIG. 13 is a polarizing microscope mirror image of untreated clinker from examples 1-5;

FIG. 14 is a polarizing microscope mirror image of the treated clinker of example 1;

FIG. 15 is a polarizing microscope mirror image of the treated clinker of example 2;

FIG. 16 is a polarizing microscope mirror image of the treated clinker of example 3;

FIG. 17 is a polarizing microscope mirror image of the treated clinker of example 4;

FIG. 18 is a polarizing microscope mirror image of the treated clinker of example 5;

FIG. 19 is a polarizing microscope mirror image of untreated clinker of examples 6-10;

FIG. 20 is a polarizing microscope mirror image of the treated clinker of example 6;

FIG. 21 is a polarizing microscope mirror image of the treated clinker of example 7;

FIG. 22 is a polarizing microscope mirror image of the treated clinker of example 8;

FIG. 23 is a polarizing microscope mirror image of the treated clinker of example 9;

FIG. 24 is a polarizing microscope mirror image of the treated clinker of example 10;

FIG. 25 is a comparison of the 60min hydration heat release rate of the treated clinker and untreated clinker of example 6 (C for treated clinker; P for untreated clinker);

FIG. 26 is a comparison of the hydration heat release rate of the treated clinker compared to the untreated clinker 1d (C is treated clinker; P is untreated clinker) of example 6;

FIG. 27 is a comparison of 2d hydration heat release rates for the treated clinker and untreated clinker of example 6 (C for treated clinker; P for untreated clinker);

FIG. 28 is a comparison of the cumulative exotherm for 2d hydration of treated clinker versus untreated clinker in example 6 (C for treated clinker; P for untreated clinker).

Detailed Description

Unless defined otherwise, technical terms used in the following examples have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods are conventional methods unless otherwise specified. The present invention will be described in detail with reference to examples.