阅读说明：本技术 一种缓凝硅酸盐水泥及其制备方法 (Retarded portland cement and preparation method thereof ) 是由 孙小培 周正明 于 2019-11-10 设计创作，主要内容包括：本发明提供一种缓凝硅酸盐水泥的制备方法,属于建筑材料领域,包括合并石灰质原料、粘土质原料和铁质原料,粉磨制备生料；合并生料和矿化剂,于高温下烧结,冷却后,二次粉磨制得上述水泥熟料；合并水泥熟料、胶凝材料和石膏,粉磨后获得缓凝硅酸盐水泥。本发明提供的制备方法能将水泥水化诱导期时间延长且降低水化热,延迟温峰出现时间,固化氯离子和降低氯离子扩散系数,提升水泥抗氯离子侵蚀能力和耐久性,所得水泥28d龄期时强度超过65MPa,且耐腐蚀性和耐热性能优异；所得水泥熟料能持续地提供强度发展,在连续性浸泡环境中抗折和抗压强度损失率低于5％,降低水泥体积收缩率,硫酸根离子侵蚀深度低,提高水泥抗腐蚀性能。(The invention provides a preparation method of retarded portland cement, which belongs to the field of building materials and comprises the steps of combining a calcareous raw material, a clayey raw material and an iron raw material, and grinding to prepare a raw material; mixing the raw material and mineralizer, sintering at high temperature, cooling, and grinding for the second time to obtain the cement clinker; and mixing the cement clinker, the cementing material and the gypsum, and grinding to obtain the delayed coagulation portland cement. The preparation method provided by the invention can prolong the hydration induction period of the cement, reduce the hydration heat, delay the temperature peak occurrence time, solidify chloride ions, reduce the diffusion coefficient of the chloride ions, and improve the chloride ion corrosion resistance and durability of the cement, and the strength of the obtained cement at 28d age exceeds 65MPa, and the cement has excellent corrosion resistance and heat resistance; the obtained cement clinker can continuously provide strength development, the fracture resistance and compression strength loss rate in a continuous soaking environment is lower than 5%, the cement volume shrinkage rate is reduced, the sulfate ion erosion depth is low, and the corrosion resistance of the cement is improved.)

1. A method of producing portland cement clinker, comprising: combining at least one calcareous raw material, at least one clayey raw material and at least one iron raw material, and grinding to prepare a raw material;

mixing the raw materials and at least one mineralizer, sintering at high temperature, cooling, and performing secondary grinding to obtain the cement clinker; the mineralizer is expanded vermiculite and barium titanate;

the breaking strength loss rate and the compressive strength loss rate of the cement clinker in a continuous 360-day soaking environment are lower than 5%.

2. The method for manufacturing portland cement clinker according to claim 1, wherein: SiO in the clayey raw material₂The content is controlled to be 70-95 wt%, and the alkali content is controlled to be 0.5-1.5 wt%.

3. The method for manufacturing portland cement clinker according to claim 1, wherein: the iron raw material is one or a mixture of iron ore, industrial byproducts with high iron content and wastes; preferably, the iron content in the iron raw material is controlled to be 60-85%.

4. The method for manufacturing portland cement clinker according to claim 1, wherein: the addition amount of the mineralizer is 0.05-0.15% of the weight of the raw material; the weight ratio of the expanded vermiculite to the barium titanate in the mineralizer is 1: 0.5-1.

5. The method for manufacturing portland cement clinker according to claim 1, wherein: the main component content of the portland cement clinker is controlled to be C according to the weight percentage₃S 46-54％、C₂S 21.5-29.5％、C₃A4.5-8.5％、C₄AF is 8.0 to 11 percent, and f-CaO is less than or equal to 0.5 percent.

6. The method for manufacturing portland cement clinker according to claim 1, wherein: the control range of the batching rate value of the portland cement clinker is as follows: lime saturation coefficient (KH) is 0.88-1.05, silicon ratio (SM) is 2.2-3.2, and aluminum ratio (IM) is 0.6-1.3.

7. A preparation method of retarded portland cement comprises the following steps: the Portland cement clinker, the cementitious material and the gypsum which are prepared by the preparation method of any one of claims 1 to 6 are combined, and are ground until the fineness is less than 4.0 percent, the screen residue is 0.08mm, the specific surface area is 300-²And (5) per kg of powder, namely obtaining the retarded portland cement.

8. The retarded portland cement made by the method of claim 7, wherein: the strength of the cement at 28d age exceeds 65 MPa; the fracture resistance and compressive strength loss rate of the cement in a continuous 360-day soaking environment is lower than 3%.

9. The set-retarding portland cement according to claim 8, wherein: the retarding portland cement comprises the following components in percentage by weight: 58-78% of silicate cement clinker, 17-25% of cementing material and 5-17% of gypsum.

10. The set-retarding portland cement according to claim 8, wherein: the retarded portland cement is used for preparing building materials or fireproof materials with high requirements on corrosion resistance and heat resistance.

Technical Field

The invention belongs to the field of building materials, and particularly relates to retarded portland cement and a preparation method thereof.

Background

Cement and concrete are the most widely used building materials and there is a continuous demand for them in the construction of dwellings, bridges and the like with an ever increasing population, with huge usage amounts constituting 8-10% of the total carbon emissions in the world. Cement is a binder that cures and hardens to bond other materials together. The most important cements are used as a combination of mortar and aggregate to form strong building material concrete. Concrete is required to have significant advantages in practical production, namely 1) strength development based on demand, accelerated or decelerated growth at various curing temperatures; 2) enhanced overall mechanical strength (high load capacity); 3) higher lifetime-no corrosion side reactions.

As a construction material, cement is used for improving workability (i.e., kneadability, spreadability, sprayability, pumpability, or fluidity) of a construction material such as concrete, which requires fluidity and fluidity of cement, and can keep fresh concrete plastic for a long time, facilitate casting, improve construction efficiency, while not adversely affecting later properties of concrete. Meanwhile, cement or concrete is required to be set early in practice unpredictably, and the early setting or delayed setting does not affect the overall strength of the concrete. In general, cement or concrete materials require high mechanical strength and durability. Portland cement is defined as: a hydraulic cementing material made of Portland cement clinker, 0-5% limestone or granulated blast furnace slag and a proper amount of ground gypsum is called Portland cement (Portland cement). Portland cement is mainly composed of C₃S、C₂S、C₃A and C₄The AF mineral composition, the sum of the four generally exceeding 95% of the total weight, in particular the first two silicate minerals, generally exceeding 75%. Portland cement is widely applied due to the advantages of fast setting and hardening, good freezing resistance, good carbonization resistance, small drying shrinkage, good wear resistance, high compressive strength, strong adaptability, low price and the like. However, due to the material composition and internal pore structure of cement, the corrosion resistance and heat resistance of cement materials are poor, so that the use of cement materials in projects such as those contacting with corrosive media (such as flowing fresh water, sulfate, seawater, etc.), projects with heat resistance requirements, etc. is significantly limited, and accidents such as premature failure and collapse damage are likely to occur, and huge losses are caused.

Disclosure of Invention

The invention aims to provide a preparation method of portland cement clinker, which can continuously provide strength development, has the fracture resistance and compression strength loss rate of less than 5 percent in a continuous soaking environment, can reduce the volume shrinkage of cement, has low sulfate ion erosion depth and improves the corrosion resistance of the cement.

The invention also aims to provide a preparation method of the retarded portland cement, which can prolong the hydration induction period, reduce the hydration heat, delay the time of temperature peak appearance, solidify chloride ions, reduce the diffusion coefficient of the chloride ions and improve the chloride ion corrosion resistance and durability of the cement, and the obtained cement has the strength of over 65MPa at the age of 28d and excellent corrosion resistance and heat resistance.

The technical scheme adopted by the invention for realizing the purpose is as follows:

a method of producing portland cement clinker, comprising: combining at least one calcareous raw material, at least one clayey raw material and at least one iron raw material, and grinding to prepare a raw material; mixing the raw materials with at least one mineralizer, sintering at high temperature, cooling, and performing secondary grinding to obtain the cement clinker; the fracture resistance and compressive strength loss rate of the cement clinker in a continuous 360-day soaking environment is lower than 5%. The preparation method can improve the burnability of the raw material under the high-temperature environment, and the clinker with a polycrystal configuration is formed by sintering, has the remarkable advantages of sustainable strength development, low later strength loss rate, good corrosion resistance, good wear resistance and the like, and improves the compression resistance of the portland cement.

In the invention, the calcareous raw material is selected from one or more of natural rock and industrial waste residue which take calcium carbonate, calcium oxide and calcium hydroxide as main components.

For the purposes of the present invention, the clayey raw material provides primarily the silica and alumina components, with SiO being the primary constituent₂The content is controlled to be 70-95 wt%, and the alkali content is controlled to be 0.5-1.5 wt%.

For the purposes of the present invention, a ferrous raw material is one or a mixture of several selected from iron ore, industrial by-products and wastes having a high iron content. Preferably, the iron content of the iron raw material is controlled to be 60-85%.

For the invention, the addition amount of the mineralizer is 0.05-0.15% of the weight of the raw meal; the mineralizer is expanded vermiculite and barium titanate, and the weight ratio of the mineralizer to the barium titanate is 1: 0.5-1. The addition of the mineralizer can improve the burnability of minerals in the raw materials in sintering, the perovskite structure is stably linked around the crystal by activating the crystal lattice of the clinker crystal and taking calcium and silicon atoms as cores, so that the displacement performance of the crystal (especially calcium compounds) is reduced, the clinker crystal has good integrity and a compact pore structure, the strength development can be continuously provided after the cement or concrete matrix is formed, and the fracture resistance and compression strength loss rate can be reduced especially in a continuous soaking environment; in addition, if the clinker is soaked in an acid environment, the perovskite structure in the clinker crystals can prevent calcium ions from being separated out and complexed with sulfate ions, so that the corrosion damage of sulfate is prevented, the corrosion depth of the sulfate ions is low, the cumulant of generated sulfuric acid crystals is reduced, the volume shrinkage of cement is reduced, and the sulfate corrosion resistance of a cement or concrete matrix can be enhanced.

For the invention, the high-temperature sintering temperature is 1250-1500 ℃, and the time is 30-90 min; the cooling mode adopts rapid cooling. Further, the cooled material is ground for the second time until the fineness is 0.15mm and the screen residue is less than 5 percent, and the obtained powder is cement clinker.

For the invention, the raw materials of the raw material comprise the following components in parts by weight: 63-83 parts of calcareous raw material, 7-21 parts of clay raw material and 8-15 parts of iron raw material. Furthermore, the cement raw meal is ground to a fineness of 0.08mm with a screen residue of less than 5%.

For the purposes of the present invention, the main constituent of the Portland cement clinker comprises tricalcium silicate C₃S, dicalcium silicate C₂S, tricalcium aluminate C₃A. Tetra calcium aluminoferrite C₄AF, the content of which is controlled at C by weight₃S 46-54％、C₂S 21.5-29.5％、C₃A4.5-8.5％、C₄AF is 8.0 to 11 percent, and f-CaO is less than or equal to 0.5 percent.

For the present invention, the control range of the batching rate value of the portland cement clinker is as follows: lime saturation coefficient (KH) is 0.88-1.05, silicon ratio (SM) is 2.2-3.2, and aluminum ratio (IM) is 0.6-1.3.

A preparation method of retarded portland cement comprises the following steps: the silicate cement clinker, the cementing material and the gypsum prepared by the preparation method are combined and ground until the fineness is 0.08mm, the screen residue is less than 4.0 percent, and the specific surface area is 300-360m²And (5) per kg of powder, namely obtaining the retarded portland cement. The preparation method can enable the cement to have obvious retarding effect, high heat resistance and corrosion resistance, enable the cement to be fully hydrated and enable the curing effect of chloride ions to be good, thereby inhibiting the generation of large-volume concrete cracks, improving the chloride ion corrosion resistance and durability of the cement and reducing the limitation of cement concrete construction operation.

For the invention, the gel material is one or a mixture of more of Arabic gum, silica gel, gelatin and nano-silica aerogel; more preferably a nanosilica aerogel. The cementing material not only can provide a cementing function to generate a cementing substance, but also can effectively provide low thermal conductivity so that the cement has the properties of heat resistance, heat insulation or fire prevention.

The invention also provides the retarded portland cement prepared by the method, wherein the strength of the retarded portland cement at the age of 28d exceeds 65 MPa; the fracture resistance and compressive strength loss rate of the cement in a continuous 360-day soaking environment is lower than 3%. The Portland cement has the advantages of proper setting time, sustainable strength development, low later strength loss rate, high bending strength and surface hardness, excellent corrosion resistance, and high heat resistance and heat insulation or fire prevention performance due to low thermal conductivity. The Portland cement is applied to concrete without adding an additional retarder, so that the effect of retarding can be achieved, water required for determining the slump of the concrete can be reduced, and the Portland cement alone provides compressive strength comparable to that of the additionally used retarder.

For the invention, the retarding portland cement comprises the following components in percentage by weight: 58-78% of silicate cement clinker, 17-25% of cementing material and 5-17% of gypsum.

The invention also provides the application of the retarded portland cement prepared by the method in the preparation of building materials or fireproof materials with high requirements on corrosion resistance and heat resistance. Building materials or fire-resistant materials include, but are not limited to, those used for ceilings, partitions, air ducts, marine building materials, and other similar materials.

The invention has the beneficial effects that:

1) the preparation method of the cement clinker can continuously provide strength development, can reduce the fracture resistance and compression strength loss rate in a continuous soaking environment, reduce the volume shrinkage rate of cement, has low sulfate ion erosion depth, and improves the corrosion resistance of portland cement;

2) the preparation method of the cement can prolong the hydration induction period, reduce the hydration heat, delay the time of temperature peak, achieve the effects of solidifying chloride ions and reducing the diffusion coefficient of the chloride ions, and improve the anti-chloride ion erosion capacity and durability of the cement;

3) the retarded portland cement obtained by the method has the strength of more than 65MPa at the age of 28d, has the fracture resistance and compression strength loss rate of less than 3 percent in a continuous 360-d soaking environment, has excellent mechanical strength and corrosion resistance, has high heat resistance, and improves the heat insulation and heat preservation or fire prevention performance;

4) the retarded portland cement obtained by the invention reduces the restriction of cement concrete construction operation, can be used in mass concrete construction operation, and can be used for preparing building materials or fireproof materials with high requirements on corrosion resistance and heat resistance.

The invention adopts the technical scheme to provide the retarded portland cement and the preparation method thereof, overcomes the defects of the prior art, and has reasonable design and convenient operation.

Drawings

FIG. 1 is a schematic diagram showing the change of the volume shrinkage rate of retarded portland cement in a long-term immersion environment;

FIG. 2 is a schematic diagram of the strength change of cement/cement clinker in a fresh water long-term soaking environment;

FIG. 3 is a schematic representation of the strength change of cement/cement clinker in a sodium sulfate solution long-term soaking environment;

FIG. 4 is a schematic diagram showing the diffusion concentration change of sulfate ions of retarded portland cement after different soaking times, A-example 2, B-example 5;

FIG. 5 is a schematic diagram of the temperature change curve of the portland cement slurry within 1000min of hydration reaction.

Detailed Description

The technical solution of the present invention is further described in detail below with reference to the following detailed description and the accompanying drawings:

a method of producing portland cement clinker, comprising: combining at least one calcareous raw material, at least one clayey raw material and at least one iron raw material, and grinding to prepare a raw material; mixing the raw materials with at least one mineralizer, sintering at high temperature, cooling, and performing secondary grinding to obtain the cement clinker; the fracture resistance and compressive strength loss rate of the cement clinker in a continuous 360-day soaking environment is lower than 5%. The preparation method can improve the burnability of the raw material under the high-temperature environment, and the clinker with a polycrystal configuration is formed by sintering, has the remarkable advantages of sustainable strength development, low later strength loss rate, good corrosion resistance, good wear resistance and the like, and improves the compression resistance of the portland cement.

In a preferred embodiment, the calcareous material is selected from one or more of natural rock and industrial waste residue which mainly comprise calcium carbonate, calcium oxide and calcium hydroxide. Examples include, but are not limited to, limestone, marl, carbide slag, industrial lime, lime slurry, and the like. Preferably, the calcareous material is limestone.

In a preferred embodiment, the clayey feedstock provides primarily silica and alumina components, with SiO being the primary constituent₂The content is controlled to be 70-95 wt%, and the alkali content is controlled to be 0.5-1.5 wt%. Preferably, the clayey material is quartz sandstone.

In a preferred embodiment, the ferrous material is one or a mixture of several selected from the group consisting of iron ore, industrial by-products with high iron content and waste. Preferably, the iron content of the iron raw material is controlled to be 60-85%. More preferably, the ferrous feedstock is selected from iron ore.

In a preferred embodiment, the mineralizer is added in an amount of 0.05-0.15% by weight of the raw material; the mineralizer is expanded vermiculite and barium titanate, and the weight ratio of the mineralizer to the barium titanate is 1: 0.5-1. The addition of the mineralizer can improve the burnability of minerals in the raw materials in sintering, the perovskite structure is stably linked around the crystal by activating the crystal lattice of the clinker crystal and taking calcium and silicon atoms as cores, so that the displacement performance of the crystal (especially calcium compounds) is reduced, the clinker crystal has good integrity and a compact pore structure, the strength development can be continuously provided after the cement or concrete matrix is formed, and the fracture resistance and compression strength loss rate can be reduced especially in a continuous soaking environment; in addition, if the clinker is soaked in an acid environment, the perovskite structure in the clinker crystals can prevent calcium ions from being separated out and complexed with sulfate ions, so that the corrosion damage of sulfate is prevented, the corrosion depth of the sulfate ions is low, the cumulant of generated sulfuric acid crystals is reduced, the volume shrinkage of cement is reduced, and the sulfate corrosion resistance of a cement or concrete matrix can be enhanced.

In the preferred embodiment, the high temperature sintering temperature is 1250-; the cooling mode adopts rapid cooling. Further, the cooled material is ground for the second time until the fineness is 0.15mm and the screen residue is less than 5 percent, and the obtained powder is cement clinker.

In a preferred embodiment, the raw materials of the raw material comprise the following components in parts by weight: 63-83 parts of calcareous raw material, 7-21 parts of clay raw material and 8-15 parts of iron raw material. Furthermore, the cement raw meal is ground to a fineness of 0.08mm with a screen residue of less than 5%.

In a preferred embodiment, the Portland cement clinker comprises tricalcium silicate C as the main component₃S, dicalcium silicate C₂S, tricalcium aluminate C₃A. Tetra calcium aluminoferrite C₄AF, the content of which is controlled at C by weight₃S 46-54％、C₂S 21.5-29.5％、C₃A4.5-8.5％、C₄AF is 8.0 to 11 percent, and f-CaO is less than or equal to 0.5 percent.

In a preferred embodiment, the control range of the batching rate value of the portland cement clinker is as follows: lime saturation coefficient (KH) is 0.88-1.05, silicon ratio (SM) is 2.2-3.2, and aluminum ratio (IM) is 0.6-1.3.

A preparation method of retarded portland cement comprises the following steps: the silicate cement clinker, the cementing material and the gypsum prepared by the preparation method are combined and ground until the fineness is 0.08mm, the screen residue is less than 4.0 percent, and the specific surface area is 300-360m²And (5) per kg of powder, namely obtaining the retarded portland cement. The preparation method can enable the cement to have obvious retarding effect, high heat resistance and corrosion resistance, enable the cement to be fully hydrated and enable the curing effect of chloride ions to be good, thereby inhibiting the generation of large-volume concrete cracks, improving the chloride ion corrosion resistance and durability of the cement and reducing the limitation of cement concrete construction operation.

In a preferred embodiment, the gelling material is one or a mixture of more of acacia, silica gel, gelatin and nano-silica aerogel; more preferably a nanosilica aerogel. The cementing material not only can provide a cementing function to generate a cementing substance, but also can effectively provide low thermal conductivity so that the cement has the properties of heat resistance, heat insulation or fire prevention. The gypsum has the function of retarding coagulation, and can also improve the performance of cement, such as strength and compatibility with concrete.

In the preferred embodiment, the retarded portland cement can be doped with an active mixed material to provide better strength performance, wear resistance, freezing resistance and the like; such reactive blending materials include, but are not limited to, granulated blast furnace slag, pozzolans, fly ash, and the like.

The invention also provides the retarded portland cement prepared by the method, wherein the strength of the retarded portland cement at the age of 28d exceeds 65 MPa; the fracture resistance and compressive strength loss rate of the cement in a continuous 360-day soaking environment is lower than 3%. The Portland cement has the advantages of proper setting time, sustainable strength development, high bending strength and surface hardness, excellent corrosion resistance, particularly high heat resistance due to low thermal conductivity, and heat insulation or fire prevention performance. The Portland cement is applied to concrete without adding an additional retarder, so that the effect of retarding can be achieved, water required for determining the slump of the concrete can be reduced, and the Portland cement alone provides compressive strength comparable to that of the additionally used retarder.

In a preferred embodiment, the retarded portland cement comprises the following components in percentage by weight: 58-78% of silicate cement clinker, 17-25% of cementing material and 5-17% of gypsum.

In preferred embodiments, the set retarding portland cement can further comprise 0-5 wt% of functional additives including, but not limited to, set accelerators (e.g., hydrochloric acid, sodium carbonate, etc.), set retarders (e.g., carboxylic acids and salts thereof, polysaccharides and derivatives thereof, phosphates, borates, etc.), foaming agents, air entraining agents, water repellents (e.g., magnesium stearate, calcium stearate, or aluminum stearate, etc.), superplasticizers, thickeners (e.g., cellulose ethers, guar ethers, modified starches, etc.), and mixtures thereof.

The invention also provides the application of the retarded portland cement prepared by the method in the preparation of building materials or fireproof materials with high requirements on corrosion resistance and heat resistance. Building materials or fire-resistant materials include, but are not limited to, those used for ceilings, partitions, air ducts, marine building materials, and other similar materials.

It is to be understood that the foregoing description is to be considered illustrative or exemplary and not restrictive, and that changes and modifications may be made by those skilled in the art within the scope and spirit of the appended claims. In particular, the present invention covers other embodiments having any combination of features from the different embodiments described above and below, without the scope of the invention being limited to the specific examples below.