CN112499999B

CN112499999B - Cement clinker, cement clinker preparation method and shrinkage cracking resistant low-heat silicate cement

Info

Publication number: CN112499999B
Application number: CN202011154973.2A
Authority: CN
Inventors: 黄晓军; 余培良; 莫立武; 罗红华; 朱东升; 李童; 尹燕
Original assignee: Hubei Jinglan Cement Co ltd; Nanjing Tech University
Current assignee: Hubei Jinglan Cement Co ltd; Nanjing Tech University
Priority date: 2020-10-26
Filing date: 2020-10-26
Publication date: 2022-08-02
Anticipated expiration: 2040-10-26
Also published as: CN112499999A

Abstract

The invention relates to a preparation method of novel cement clinker, which comprises the following steps: s01, obtaining raw materials, wherein the raw materials comprise dolomite, clay and mineralizer; s02, grinding and mixing the raw materials to obtain a first mixture; s03, placing the first mixture into a calcining device for calcining at 800-1200 ℃ and preserving heat for 1-3 hours; and cooling and grinding the calcined S04 to obtain the catalyst. The cement clinker mainly contains MgO mineral with low heat release quantity C2S and expansion effect, and the micro expansion generated after hydration compensates the shrinkage of the cement.

Description

Cement clinker, cement clinker preparation method and shrinkage cracking resistant low-heat silicate cement

Technical Field

The invention relates to a cement clinker, a preparation method of the clinker and portland cement prepared by applying the clinker, belonging to the field of cement minerals.

Background

Concrete is a building material with the widest application range in the current building field, but different types of damages are often generated before the design life is reached, wherein one of the key factors is that the concrete volume is unstable due to the shrinkage of a cement-based material, so that the concrete is cracked and the service life of the concrete is shortened, and even engineering accidents are generated due to serious shrinkage cracking behaviors. Generally, the shrinkage behavior of concrete is caused by the shrinkage deformation of the cement-based material contained. At present, the consumption of concrete materials is rapidly increased, and the shrinkage behavior of cement-based materials in concrete is increasingly attracting the attention of experts and scholars at home and abroad, so a great deal of research work is carried out in this respect.

The concrete has more influencing factors of the shrinkage of cement-based materials, but the following factors are generally considered to have greater effects, including the types of cement, the types of mineral admixtures, the aggregate quality, the mix proportion design, chemical admixtures and the like. The mineral composition of the cement is in general C ₃ S、C ₂ S、C ₃ A and C ₄ And (5) AF. After the hydration reaction of the above-mentioned several minerals, the volume change is C from large to small ₃ A、C ₃ S、C ₂ S and C ₄ And (5) AF. Thus, the effect of cement hydration on shrinkage behaviour is largely determined by its specific mineral composition. At present, the common measure for solving the shrinkage and cracking of cement-based materials is to use expansion cement or directly add an additive with expansion performance, such as ettringite, calcium oxide, magnesium oxide expanding agent and the like. However, ettringite and calcium oxide have the defects of large water requirement for hydration, unstable physical and chemical properties of hydration products and uncontrollable expansion process, and although the water requirement of the magnesium oxide expanding agent is relatively low, all the additives consume a large amount of energy in the production process, so that the aims of energy conservation and environmental protection cannot be fulfilled. Meanwhile, the external doping process is complex, and the defects restrict the application of the expanding agent in concrete (particularly mass concrete). Therefore, a new functional cement is needed to be found, which not only has small heat release and good anti-cracking effect, but also can be directly used in actual engineering, so that the cement achieves convenient construction, low cost and anti-cracking effect through shrinkage compensation. According to the subject of 'key materials and technologies of energy and cement-based for road engineering in complex environment' of thirteen five national key research and development projects: the research and application of the micro-expansion high-shrinkage cracking resistance low-heat silicate cement-based material for hydroelectric engineering are significant in the research of the novel shrinkage cracking resistance low-heat silicate cement.

Disclosure of Invention

The invention aims to provide novel environment-friendly shrinkage cracking resistant low-heat portland cement which can reduce the heat release of cement hydration and has the effects of compensating shrinkage and resisting cracking.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

the invention provides a cement clinker for preparing shrinkage cracking resistant low-heat portland cement, which mainly contains low-C with low heat release ₂ S and MgO mineral with expansion effect, the micro expansion generated after hydration compensates the contraction of the cement.

The preparation method of the novel cement clinker comprises the following steps:

s01, obtaining raw materials, wherein the raw materials comprise dolomite, clay and a mineralizer;

s02, grinding and mixing the raw materials to obtain a first mixture;

s03, placing the first mixture into a calcining device for calcining at 800-1200 ℃ and preserving heat for 1-3 hours;

and cooling and grinding the calcined S04 to obtain the catalyst.

Further, in the step S02, the particle size of the first mixture is smaller than 80 μm.

Furthermore, the mass percentage of each component in the dolomite in the raw material is MgO>20% and CaO>30 percent; the mass percentage of each component in the clay is SiO ₂ >50％，Al ₂ O ₃ ＜20％，Fe ₂ O ₃ >4％。

Furthermore, the CaF mass content in the mineralizer in the raw material is more than 95 percent of CaF.

Further, the mass ratio of dolomite, clay and mineralizer in the raw materials is as follows:

further, the temperature rise rate in the calcination process in step S03 is 5-6 ℃/min, and the cooling manner in step S04 is air quenching.

Further, the novel cement clinker comprises the following components in percentage by mass:

C ₂ S 40％—60％，

MgO 20％—30％；

0-6% of free CaO;

does not contain C ₃ S、C ₃ And A mineral.

Further, in the first mixture, the ratio of CaO: SiO 2 ₂ The mass ratio of (A) to (B) is 2: 1.

The shrinkage cracking resistant low-heat silicate cement prepared by the cement clinker comprises the following components in percentage by mass:

10 to 40 percent of clinker aggregate

60 to 90 percent of clinker aggregate

2 to 5 percent of gypsum

The clinker I is prepared by the following method:

s02, grinding the raw materials and mixing to obtain a mixture I;

s04, cooling and grinding after calcination is finished to obtain the catalyst;

and the clinker II is portland cement clinker.

When the calcining temperature and the heat preservation time are too low, the novel cement clinker does not have strength and expansion performance; too high temperature and holding time, too large expansion amount and easy to cause poor stability. The preferred calcination temperature is 1050 ℃ and the holding time is 2 hours.

Preferably, the second clinker accounts for 66%, the first clinker accounts for 30% and the gypsum accounts for 4%.

Further, the portland cement comprises the following components in parts by mass:

the invention has the beneficial effects that 1, the invention adopts dolomite, clay and mineralizer which are crushed and ground to be less than 80 mu m as main raw materials, and has lower calcining temperature and less energy consumption compared with the conventional cement. Meanwhile, the raw material resources are rich and easily available, the cost is low, the benefit is high, and the processing and manufacturing process is simple.

2. C in novel cement clinker obtained by calcination ₂ S can delay the hydration process in the conventional cement, delay the acceleration period of the hydration of the cement and reduce the heat released in the hydration process of the cement. And C ₃ S phase ratio, C ₂ The smaller amount of CH in S hydrate favors the development of set strength, since CH contributes much less to set strength than C-S-H. Generally, the larger the volume ratio of C-S-H to CH in hydrate is, the higher the later strength of the compressive strength of the cement is, and meanwhile, the MgO and CaO expand during hydration, so that the volume shrinkage deformation generated by the hydration of the cement can be effectively compensated, and the problem of concrete cracking due to shrinkage is greatly reduced.

3. The performance of the novel cement clinker is different at different calcining temperatures, the dolomite is completely decomposed at about 900 ℃, and the product mainly comprises a mixture of CaO and MgO and SiO in clay ₂ Under the melting promotion action of the mineralizer, the mineralizer starts to perform solid-phase reaction with CaO to generate C ₂ S, because the reaction is slowly carried out at a lower temperature, a large amount of CaO still exists in the product after the heat preservation is carried out for 2 hours. When the calcination temperature reaches 1050 ℃, preserving the heat for 2 hours to obtain the product mainly containing C ₂ S and MgO are main components, and the CaO content is lower than 6 percent. Therefore, the novel shrinkage cracking resistant low-heat silicate cement with different properties can be obtained by adopting different calcination temperatures and different heat preservation times, so as to meet the requirements of different projects on shrinkage compensation cracking resistance, low hydration heat release and standard strength.

4. In the preparation process of the novel shrinkage cracking resistant low-heat portland cement, the ratio of the novel cement clinker can reach 50 percent at most, the calcining temperature is lower than 1100 ℃, the calcining temperature is 350 ℃ lower than that of the conventional cement clinker, and the novel cement clinker is easy to grind, so that the energy consumption and the cost can be greatly reduced, and the environmental pollution is reduced.

5. When the novel shrinkage cracking resistant low-heat silicate cement is used for preparing large-volume concrete, no expanding agent is required to be added, and the deformation values of the novel shrinkage cracking resistant low-heat silicate cement when the self-generated volume deformation is 14d are respectively-5.2 multiplied by 10 ^-6 —38.6×10 ^-6 (ii) a The deformation values at 180d are respectively 0-125.3 multiplied by 10 ^-6 . At the same timeThe heat release of the concrete is low, the 3d accumulated heat release is 214.9-260.2 kJ/g, the water cooling temperature control measures can be reduced, and the construction cost is reduced.

6. When the novel shrinkage cracking resistant low-heat silicate cement slurry is cured at the temperature of 20 ℃ for 28 days, the expansion rate values of the test pieces are 0.095-0.145% respectively; the expansion ratio of the test pieces was 0.148 to 0.275% at 360 d.

7. The compressive strength value of the novel shrinkage cracking resistant low-heat silicate cement mortar test piece at the standard curing age for 28 days is 42.5-52.5 MPa.

Drawings

FIG. 1(a) shows XRD patterns of example 1, example 5 and example 2 from top to bottom in this order

FIG. 1(b) shows XRD patterns of example 8, example 6 and example 3 from top to bottom;

FIG. 1(c) shows XRD patterns of example 9, example 7 and example 4 from top to bottom

FIG. 2(a) Heat flux curves for reference, examples 1, 2, 3 cements;

FIG. 2(b) hydration heat curves for reference, example 1, 2, 3 cements;

FIG. 3 deformation of cement paste under water curing conditions at 20 ℃;

FIG. 4 shows the autogenous volume deformation of concrete at 20 ℃.

Detailed Description

The present invention is described in further detail below with reference to specific embodiments and the attached drawings, but it should be understood that the scope of the present invention is not limited by the specific embodiments.

The properties of the novel shrinkage cracking resistant low heat portland cement were evaluated by measuring the hydration heat of the novel shrinkage cracking resistant low heat portland cement, the volume deformation of the concrete itself, the cement paste expansion rate, and the strength of the mortar test block at the corresponding curing age in the following examples and comparative examples.

Example 1

Novel cement clinker preparation method

The chemical composition of the raw materials used in the tests is shown in table 1.

TABLE 1 chemistry of the raw materials

Raw materials	Loss	SiO ₂	CaO	MgO	Fe ₂ O ₃	Al ₂ O ₃	SO ₃	Total
									Dolomitic rock	46.80	1.55	29.46	21.03	0.26	0.47	—	99.57
Clay	8.00	61.74	2.71	2.46	5.90	14.27	—	95.08

a) Respectively mixing dolomite (MgO mass content is more than 20%) and clay (SiO) ₂ Mass content is more than 50%), drying, crushing and grinding until all the powder passes through a 0.08mm sieve, and obtaining dolomite grinding and clay grinding for later use. Then mixing the standby dolomite with clay powder according to the mass ratio (dolomite: clay: 421:100), and doping CaF with the raw material with the mass fraction of 1% ₂ Mix on the blender for 24 h. Taking about 50g of materials each time, adding water with the mass fraction of 4% of the raw materials, maintaining the pressure for 4s under the pressure of 6MPa, preparing into a cube block of 5cm multiplied by 1cm, and placing the cube block in an oven for drying for 3-4h at 105 ℃.

b) Placing the prepared material in a sagger, putting the sagger into calcining equipment for calcining and preserving heat; the calcining equipment can be one or more of a resistance furnace, a fluidized bed furnace and a converter, the heating rate is 5-6 ℃/min, the calcining temperature is 1050 ℃, and the heat preservation time is 2 h.

c) Taking out the calcined product for cooling, performing ball milling to obtain powder, wherein the cooling mode is air quenching, the product is cooled to room temperature by blowing with a high-power fan, the calcined product needs to be taken out quickly, the air quenching is performed, the rotating speed is 2500 plus 3000 r/min, the product is ground after being cooled, the powder is sieved by a 0.08mm square-hole sieve, the sieve residue is less than 10%, and the obtained novel shrinkage cracking resistant low-heat portland cement clinker is stored for later use by a sealing bag.

Example 2

The difference from example 1 is that: the calcining temperature is 950 ℃, and the heat preservation time is 1 h.

Example 3

The difference from example 1 is that: the calcining temperature is 950 ℃, and the heat preservation time is 2 hours.

Example 4

The difference from example 1 is that: the calcining temperature is 950 ℃, and the heat preservation time is 3 hours.

Example 5

The difference from example 1 is that: the calcining temperature is 1000 ℃, and the heat preservation time is 1 h.

Example 6

The difference from example 1 is that: the calcining temperature is 1000 ℃, and the heat preservation time is 2 h.

Example 7

The difference from example 1 is that: the calcining temperature is 1000 ℃, and the heat preservation time is 3 h.

Example 8

The difference from example 1 is that: the calcining temperature is 1050 ℃, and the holding time is 1 h.

Example 9

The difference from example 1 is that: the calcining temperature is 1050 ℃, and the holding time is 3 h.

The XRD patterns and the compositional analyses of the products prepared in examples 1-9 are shown in FIGS. 1 and 2

TABLE 2F-CaO and f-MgO contents in the novel cement clinker

As can be seen from the graphs of (a), (b) and (C) in FIG. 1, when the temperature is kept at 950 ℃ for 1h, dolomite is completely decomposed into f-CaO and f-MgO, obvious diffraction peaks of f-CaO and periclase exist, and beta-C can be detected ₂ S and C ₁₂ A ₇ (dodecacalcium heptaluminate), in addition, there are clear quartz diffraction peaks. When the novel cement clinker is calcined at 1000 ℃ and 1050 ℃ for 1h, the mineral phase in the novel cement clinker is similar to that at 950 ℃, and only the f-CaO diffraction peak in the novel cement clinker is obviously reduced when the novel cement clinker is calcined at 1050 ℃. The mineral phase in the novel cement clinker prepared by calcining at 950 ℃, 1000 ℃ and 1050 ℃ is also composed of periclase and beta-C when the temperature is kept for 2 hours ₂ S、C ₁₂ A ₇ Quartz and f-CaO; compared with the heat preservation for 1h, the novel cement clinker prepared by preserving the heat for 2h has weakened f-CaO and quartz diffraction peaks at the same calcination temperature. Keeping the temperature at 950 ℃ and 1000 ℃ for 3hThe novel cement clinker prepared by calcining at 1050 ℃ is also prepared from periclase and beta-C ₂ S、C ₁₂ A ₇ The diffraction peaks of the f-CaO and the quartz in the novel cement clinker prepared by only preserving heat for 3 hours are obviously reduced, and the diffraction peaks of the f-CaO can hardly be detected in the novel cement clinker prepared by calcining at 1050 ℃ for 3 hours. Therefore, the f-CaO and quartz diffraction peaks in the prepared novel cement clinker can be weakened and the beta-C can be reduced by prolonging the heat preservation time or increasing the calcining temperature ₂ The S diffraction peak is enhanced.

As can be seen from Table 2, the f-CaO content of the novel cement clinker obtained by calcining at 950 ℃, 1000 ℃ and 1050 ℃ was 13.47%, 6.61% and 4.53%, respectively, after the heat preservation for 1 hour; when the temperature is kept for 2 hours, the f-CaO content of the novel cement clinker prepared by calcining at 950 ℃, 1000 ℃ and 1050 ℃ is respectively 9.24 percent, 4.42 percent and 2.53 percent; when the temperature is kept for 3 hours, the f-CaO content of the novel cement clinker prepared by calcining at 950 ℃, 1000 ℃ and 1050 ℃ is 7.40 percent, 3.01 percent and 1.41 percent respectively. Therefore, the increase of the calcination temperature or the extension of the holding time is beneficial to f-CaO and SiO ₂ Solid-phase reaction to form beta-C ₂ And S, further gradually reducing the content of f-CaO. When the temperature is kept for 1h, the f-MgO content in the novel cement clinker is respectively 28.06%, 27.83% and 28.39% at 950 ℃, 1000 ℃ and 1050 ℃; when the temperature is kept for 2 hours, the f-MgO content in the novel cement clinker is respectively 27.78 percent, 27.54 percent and 29.01 percent at 950 ℃, 1000 ℃ and 1050 ℃; when the temperature is kept for 3 hours, the f-MgO content in the novel cement clinker is respectively 28.21 percent, 28.53 percent and 29.51 percent at 950 ℃, 1000 ℃ and 1050 ℃. Thus, the calcination temperature and holding time under the present test conditions had no significant effect on the periclase content of the novel cement clinker.

Example 10

Preparation of shrinkage cracking resistant low-heat silicate cement

The clinker I used in the test was the clinker prepared in example 1, and the clinker II, i.e. Portland cement clinker (PC) from Chinese cement plant, the chemical composition of which is shown in Table 3, and the main mineral phase C was calculated from the results of the chemical analysis ₃ S、C ₂ S、C ₃ A and C ₄ Of AFThe contents were 67.85%, 6.99%, 6.5% and 11.76%, respectively, and the chemical compositions of the other main raw materials are shown in table 1.

TABLE 3 chemistry of the raw materials

Raw materials	Loss	SiO ₂	CaO	MgO	Fe ₂ O ₃	Al ₂ O ₃	SO ₃	Total
									Clinker II	0.76	20.29	64.82	2.21	3.87	4.94	0.57	97.46
Gypsum plaster	8.36	2.88	35.14	0.33	0.25	0.32	48.54	95.82

The preparation proportion of the novel shrinkage cracking resistant low-heat silicate cement is as follows: 85% of clinker II, 10% of clinker I and 5% of gypsum.

Example 11

The difference from example 10 is that: the preparation proportion of the novel shrinkage cracking resistant low-heat silicate cement is as follows: 75% of second clinker, 20% of first clinker and 5% of gypsum, and the rest methods are the same as those of the example 10.

Example 12

The difference from example 10 is that: the preparation proportion of the novel shrinkage cracking resistant low-heat silicate cement is as follows: 65% of second clinker, 30% of first clinker and 5% of gypsum, and the rest methods are the same as those of example 10.

COMPARATIVE EXAMPLE (REFERENCE SAMPLE)

Only clinker two is used.

The hydration heat of the novel shrinkage crack resistant low heat portland cement prepared by the above method is shown in fig. 2(a) and (b), and the hydration heat release curves of the cements of comparative example, examples 10, 11, and 12. From the figure, the reference sample cement reaches the peak value of the heat release rate within about 10 hours, the cement in examples 10, 11 and 12 obviously delays the acceleration period of cement hydration, the heat release peak value is reached within about 14 hours, and the hydration heat release peak value is obviously reduced along with the increase of the mixing amount of the novel cement clinker. In the examples 10, 11 and 12, the hydration heat in the first 6h is slightly increased, and the cement hydration heat tends to be reduced after 6h along with the increase of the addition amount of the clinker. The exotherms of the reference cement and the cements of examples 10, 11 and 12 increase mainly within 24h, and thereafter the rate of increase slows down and the curve flattens. The reference sample cement has the largest heat release, and the heat release of the cement doped with the clinker I is reduced along with the increase of the doping amount. The reference cement and 3d cement of examples 10, 11 and 12 had cumulative exotherms of 280.01kJ, 260.24kJ, 230.95kJ and 214.93kJ, respectively.

The new shrinkage cracking resistant low heat silicate cement slurries of examples 10, 11 and 12 were formed by using a 20mm x 80mm mold, 6 continuous test mold and with nail heads at both ends. The water-to-glue ratio is 0.28. The test is carried out according to JC/T313-2009 expansion rate test method for expansive cement. Curing the molded test piece for 24 +/-2 h under standard curing conditions, demolding and measuring the initial length L of the test piece ₀ . Then placing the test piece into water with the temperature of 20 ℃ for maintenance to corresponding age, taking out the test piece in each age to measure the length L of the test piece ₁ And ensuring that the test environment is the same as the first time and the expansion rate L of the test piece _A And calculating a formula: l is _A ＝[(L ₁ -L ₀ )/L]X 100%, wherein L is the effective length of the test piece, and L is 80 mm. The specimen expansion takes into account the error while taking the arithmetic mean of the six specimens as a result.

FIG. 3 is a swelling deformation curve of the cement paste of reference sample, examples 10, 11 and 12, under water curing conditions at 20 ℃. As can be seen from fig. 4, the cement slurries of the reference sample, examples 10, 11 and 12 all swelled at 0.048%, 0.08%, 0.092% and 0.119% respectively in the initial stage of hydration 14 d. The expansion rate of the reference sample cement slurry then slowly decreased as the curing age extended. The expansion rate of the cement paste of examples 10, 11 and 12 continued to increase with the increase of the curing age. The expansion rate of the cement paste of the example 10 gradually becomes flat after 300d, the expansion rate of the cement paste of the example 11 slightly increases, the expansion rate of the cement paste of the example 12 still significantly increases, and the expansion rate values of the cement pastes of the examples 10, 11 and 12 without the reference sample are 0.007%, 0.148%, 0.188% and 0.275% at 360 d.

The concrete prepared from the novel shrinkage cracking resistant low-heat portland cement cements of the obtained examples 10, 11 and 12 has self deformation, and the concrete mixing ratio is as follows: the dosage of the cement material is 378kg/m ³ (ii) a 170kg/m of water ³ (ii) a Sand ratio of 40%; stone of 5-31.5mm continuous gradation 1167kg/m ³ (ii) a 0.75 percent of polycarboxylic acid high-efficiency water reducing agent. The deformation performance test is carried out according to GB/T50082-2009 test method standards for the long-term performance and the durability of the common concrete, and the strain gauge is adopted to measure the volume deformation of the common concrete; the test mold is a customized PVC plastic cylinder with the diameter of 25cm and the height of 50cm, and a test piece is sealed by epoxy resin after being formed.

FIG. 4 shows autogenous volume deformation of the concrete samples prepared from the reference sample and the cement of examples 10, 11 and 12 under the air curing condition at 20 ℃. From fig. 4, it can be found that the concrete test piece prepared by the reference sample cement generates certain shrinkage deformation along with the hydration of the clinker. Example 10 cement preparation concrete test pieces were affected by the self-contraction effect of clinker hydration at the initial stage of curing, and the samples were in a contracted state. As the periclase was gradually hydrated, the sample gradually assumed a slightly expanded state, and by 180 days, the deformation value of the concrete specimen prepared from the cement of example 10 was-21.5X 10-6. The concrete samples prepared by cement in examples 10 and 11 have relatively small self-contraction effect caused by hydration of clinker in the initial curing period because the content of the novel clinker is relatively high. On the other hand, the content of periclase in the clinker is high, and the expansion generated by hydration compensates the shrinkage effect of clinker hydration. 40d to 180d are hydrated by periclase, the expansion growth is obvious, and the deformation value of 180d is 60.1 multiplied by 10 respectively ^-6 And 125.3X 10 ^-6 . Because the periclase with low activity usually causes larger later deformation, the concrete sample prepared by the cement of the example 3 still has the tendency of increasing expansion rate at the later stage, and the deformation curve of the example 11 gradually becomes flat. The proper novel cement clinker can effectively compensate the shrinkage effect of clinker hydration and generate proper expansion amount.

The novel shrinkage cracking resistant low-heat silicate cements of the examples 10, 11 and 12 were prepared into cement mortar test blocks of 40mm × 40mm × 160mm according to a cement-to-sand ratio (ratio of binding material to sand) of 1:3 and a water-to-glue ratio (ratio of blended water to binding material) of 0.5, and the strengths of the mortar test blocks at different ages were measured, the mortar strength tests were performed according to GB/T17671-1999 "cement mortar Strength test", the mortar curing ages were 7d, 28d and 90d, respectively, and the results are shown in Table 2.

Table 2 shows the compressive strength values of the reference sample, the cement mortar test pieces of examples 10, 11 and 12 at different curing ages. The mortar specimens of the reference sample had higher compressive strength values at ages 7d and 28d than those of the mortar specimens of examples 10, 11 and 12, 35MPa and 50MPa, respectively, and the mortar specimen of example 11 had the highest compressive strength value at age 90d, 54 MPa. The compressive strength of the mortar samples 28d and 90d in example 11 is higher than that of the mortar samples in examples 10 and 12. The compressive strength values of 7d of the cement mortar test pieces of examples 10, 11 and 12 were respectively reduced by 5.7%, 20.0% and 31.4% compared to the mortar test pieces of the reference sample, and the compressive strength values of 28d were relatively reduced by 10.0%, 2.0% and 14.0%. The compressive strength by age 90d was only slightly less than that of example 3 for the reference. The compressive strength of all the cement mortar test pieces of the examples is greater than that of the reference test piece when the cement mortar test piece is aged to 180 d.

TABLE 2 compressive Strength/MPa of mortar

The above description is only a preferred embodiment of the present invention, and the present invention is not limited to the content of the embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the technical scope of the present invention, and any changes and modifications made are within the protective scope of the present invention.

Claims

1. A preparation method of cement clinker is characterized in that: the method comprises the following steps:

s01, obtaining raw materials, wherein the raw materials comprise dolomite, clay and a mineralizer; the mass percentage of MgO and CaO in the dolomite is MgO>20% and CaO>30 percent; the clay contains SiO ₂ 、Al ₂ O ₃ And Fe ₂ O ₃ And the mass percentage of each component is SiO ₂ >50%，Al ₂ O ₃ ＜20%，Fe ₂ O ₃ >4 percent; the mass content of CaF in the mineralizer is CaF>95%；

S02, grinding and mixing the raw materials to obtain a first mixture;

s03, placing the first mixture into a calcining device to be calcined at 1050 ℃ and keeping the temperature for 2 hours; the temperature rise rate in the calcining process is 5-6 ℃/min;

s04, cooling and grinding after the calcination is finished, and the cooling mode in the step S04 is air quenching;

the cement clinker comprises the following components in percentage by mass:

C ₂ S 40%—60%，

MgO 20%—30%；

0 to 6 percent of free CaO.

2. The method for producing cement clinker according to claim 1, wherein: in step S02, the grain size of the first mixture is less than 80 μm.

3. The method for producing cement clinker according to claim 1, wherein: CaO in the first mixture: SiO 2 ₂ The mass ratio of (A) to (B) is 2: 1.

4. A cement clinker produced by the production method according to claim 1.

5. The shrinkage cracking resistant low-heat silicate cement is characterized in that: the composite material comprises the following components in percentage by mass:

10 to 40 percent of clinker aggregate

60 to 85 percent of clinker aggregate

2 to 5 percent of gypsum

The clinker is prepared by the method of claim 1;

the clinker II is silicate cement clinker; the portland cement comprises the following components in parts by mass:

C ₃ S 50-60%；

C ₂ S 20-33%；

C ₃ A 7-15%；

C ₄ AF 10-18%。

6. the shrinkage cracking resistant low heat portland cement according to claim 5, wherein: 66% of clinker II, 30% of clinker I and 4% of gypsum.