CN110386785A - Cement substitute composition and its preparation method and application - Google Patents

Abstract

The present invention relates to the field of building materials, disclose cement substitute composition and its preparation method and application.A kind of cement substitute composition, with the total weight of cement substitute composition, cement containing 50-70 weight %, and the fly ash composition of 30-50 weight %, wherein, the fly ash composition contains D90 and is being greater than 8 μm in 8 μm of flyash I below and optional D90 and is being 90 μm of flyash II below, and with the total weight of cement substitute composition, the content of flyash I is greater than 10 weight %.In cement substitute composition of the invention, the addition content of flyash can achieve 50 weight %, and 28 days compression strength of sample are suitable with the compression strength of striaght cement.When the addition content of flyash is controlled in 30 weight %, 28 days compression strength of sample can reach 1.15 times of the compression strength of striaght cement.

Description

Cement replacement composition, preparation method and application thereof

technical field

The invention relates to the field of building materials, in particular to a cement replacement composition, a preparation method and application thereof.

Background technique

Fly ash is one of the main industrial solid wastes in my country. With the rapid development of the power industry, the total amount of fly ash emitted by coal-fired thermal power plants is increasing year by year. It is a bulk industrial waste, but it is also a substance with potential pozzolanic activity, so it can be used in the building materials industry. At present, the application of fly ash in the field of building materials in my country mainly includes: roadbed filling materials, wall materials, fly ash cement and concrete admixtures. Although these methods can treat part of fly ash, the utilization level is low, and the pozzolanic activity of fly ash is not fully utilized. Fly ash is an effective way to use fly ash to prepare cement or as an admixture for cement concrete, but the amount is limited. A large amount of accumulated fly ash not only occupies land, but also seriously pollutes the environment. Therefore, how to improve the utilization rate and utilization level of fly ash has become an important issue to be solved urgently.

Great achievements have been made in the development of my country's cement industry, but the structural contradictions are relatively prominent, mainly as follows: the cement production process has high energy consumption. Specifically, the cement production process requires the process of "two grinding and one burning"; the impact on the environment is mainly dust pollution, and its dust emissions account for about 40% of the total industrial dust emissions in the country. Although the country pays more and more attention to the environmental protection of the cement industry, and the total amount of dust emissions in cement production is decreasing year by year, the pollution problem is still very serious. At present, the dust emission concentration of most shaft kiln and dry process hollow kiln enterprises seriously exceeds the standard. If fly ash is used to partially replace cement, it can not only reduce dust pollution, but also reduce production energy consumption.

CN104370486A discloses the preparation process and application of high-performance composite material activated ultrafine fly ash. The secondary or tertiary ash is superfinely ground while adding 0.8% activator and 0.05% grinding aid by weight of fly ash. Co-grinding, the proportion of particles less than 10 μm in size exceeds 95%. It is mixed with 10-20% in 32.5 cement and 10-15% in 42.5 cement, mixed evenly, and the grade of the produced cement is unchanged.

CN102010143A discloses a preparation method of modified secondary fly ash used in concrete, the raw material composition and weight percentage of modified secondary fly ash used in concrete are: secondary fly ash 60-85%, super Fine steel slag powder 10-30%, hemihydrate gypsum 3-12%.

CN103466977A discloses a preparation method of cement substitute raw material. Fly ash is added to wet-draining carbide slag with a moisture content of 80-95%, and the amount of fly ash added is 14-20 g per 100 g of wet-draining carbide slag. fly ash.

But, in the existing scheme, the mixing amount of fly ash is limited, mostly about 20%, when the mixing amount reaches 30%, the 28-day compressive strength is generally lower than the pure cement sample, even if 1 The 28-day compressive strength of the sample can reach up to the compressive strength of pure cement when the mixing amount reaches 30%.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the problem that the mixing amount of fly ash is low in the prior art, and the 28-day compressive strength of the sample is greatly reduced after the mixing amount of fly ash reaches 30%, and provides a cement substitute composition and In the preparation method and application thereof, in the cement replacement composition of the present invention, the admixture of fly ash can reach 50% by weight, and the 28-day compressive strength of the sample is comparable to that of pure cement. When the mixing amount of fly ash is controlled at 30% by weight, the 28-day compressive strength of the sample can reach 1.15 times that of pure cement.

In order to achieve the above object, a first aspect of the present invention provides a cement replacement composition, wherein, based on the total weight of the cement replacement composition, it contains 50-70% by weight of cement and 30-50% by weight of fly ash combined wherein the fly ash composition contains fly ash I with a D90 of less than 8 μm and optional fly ash II with a D90 of greater than 8 μm and less than 90 μm, and based on the total weight of the cement replacement composition, The content of fly ash I is greater than 10% by weight.

Preferably, the content of fly ash I is greater than 20% by weight, based on the total weight of the cement replacement composition.

Preferably, the composition of fly ash I is the same or different from that of fly ash II.

Preferably, the composition of the fly ash I contains 1-66 wt % SiO ₂ , 0-4 wt % TiO ₂ , 1-41 wt % Al ₂ O ₃ , 1-7 wt % Fe _{2 O3} , 0-5 wt% FeO, 0-3 wt% _MnO2 , 1-4 wt% MgO, 1-17 wt% CaO, 0.1-5 wt% Na2O, 0.1-5 wt _% % K ₂ O, 0-3 wt % P ₂ O ₅ and 0-6 wt % SO ₃ .

Preferably, the composition of the fly ash II contains 1-66 wt % SiO ₂ , 0-4 wt % TiO ₂ , 1-41 wt % Al ₂ O ₃ , 1-7 wt % Fe _{2 O3} , 0-5 wt% FeO, 0-3 wt% _MnO2 , 1-4 wt% MgO, 1-17 wt% CaO, 0.1-5 wt% Na2O, 0.1-5 wt _% % K ₂ O, 0-3 wt % P ₂ O ₅ and 0-6 wt % SO ₃ .

Preferably, the cement is one or more of ordinary Portland cement, slag Portland cement, pozzolanic Portland cement, fly ash Portland cement and composite Portland cement.

Preferably, the cement is ordinary Portland cement.

A second aspect of the present invention provides a method for preparing a cement replacement composition, comprising mixing 50-70% by weight of cement and 30-50% by weight of a fly ash composition, wherein the fly ash composition contains Fly ash I with a D90 below 8 μm and optionally fly ash II with a D90 of greater than 8 μm and below 90 μm, and the content of fly ash I is greater than 10 wt % based on the total weight of the cement replacement composition.

Preferably, the content of fly ash I is greater than 20% by weight, based on the total weight of the cement replacement composition.

The third aspect of the present invention provides the application of the above-mentioned cement replacement composition as a building material.

The present invention uses fly ash I with a D90 of less than 8 μm and optional fly ash II with a D90 of greater than 8 μm and less than 90 μm, and defines that the content of fly ash I based on the total weight of the cement replacement composition is greater than 10% by weight, preferably more than 20% by weight, so that the amount of fly ash added can reach 50% by weight, and the 28-day compressive strength of the sample can still reach the compressive strength of pure cement. The addition of 50% by weight of fly ash greatly increases the amount of fly ash, which not only realizes the utilization of waste, but also reduces the production cost of cement, solves the problems of high energy consumption and dust pollution in cement production, and does not reduce 28 compressive strength. In addition, if the content of fly ash is controlled at 30% by weight based on the total weight of the cement replacement composition, the 28-day compressive strength of the sample can reach 1.15 times that of pure cement. And in the present invention, the flexural strength is comparable to the existing level.

Detailed ways

The endpoints of ranges and any values disclosed herein are not limited to the precise ranges or values, which are to be understood to encompass values proximate to those ranges or values. For ranges of values, the endpoints of each range, the endpoints of each range and the individual point values, and the individual point values can be combined with each other to yield one or more new ranges of values that Ranges should be considered as specifically disclosed herein.

A first aspect of the present invention provides a cement replacement composition, wherein, based on the total weight of the cement replacement composition, it contains 50-70% by weight of cement and 30-50% by weight of a fly ash composition, wherein the The fly ash composition contains fly ash I with a D90 of less than 8 μm and optional fly ash II with a D90 of greater than 8 μm and less than 90 μm, and based on the total weight of the cement replacement composition, the amount of the fly ash I is The content is greater than 10% by weight.

In a preferred embodiment of the present invention, the content of fly ash I is greater than 20% by weight, based on the total weight of the cement replacement composition.

In the present invention, fly ash I with D90 below 8 μm and fly ash II with D90 greater than 8 μm and below 90 μm are obtained by cyclone classification. The cyclone classification method is a conventional method in the art and will not be repeated here.

In the present invention, the method for measuring the particle size of D90 is a conventional method in the art, such as, but not limited to: measuring by a laser particle size analyzer.

In the present invention, the composition of fly ash I and fly ash II may be the same or different. The compositions of the fly ash I and fly ash II of the present invention may be conventional chemical components in the art, and are not particularly limited.

Specifically, the composition of the fly ash I may contain, but is not limited to: 1-66 wt % SiO ₂ , 0-4 wt % TiO ₂ , 1-41 wt % Al ₂ O ₃ , 1-7 wt % wt% _Fe2O3 , 0-5 wt% FeO, _0-3 wt% _MnO2 , 1-4 wt% MgO, 1-17 wt% CaO, 0.1-5 wt _% Na2O , 0.1-5 wt% K2O, _0-3 wt _{% P2O5} and _0-6 wt% SO3.

The composition of the fly ash II may contain but not limited to: 1-66 wt% SiO ₂ , 0-4 wt % TiO ₂ , 1-41 wt % Al ₂ O ₃ , 1-7 wt % _Fe2O3 , 0-5 wt% FeO, _0-3 wt% _MnO2 , 1-4 wt% MgO, 1-17 wt% CaO, 0.1-5 wt _% Na2O, 0.1- ₅ wt% K2O, _0-3 wt% _P2O5 and _0-6 wt% SO3.

In the present invention, the cement may be one or more of ordinary Portland cement, slag Portland cement, pozzolanic Portland cement, fly ash Portland cement and composite Portland cement.

In a preferred embodiment, the cement is ordinary Portland cement. The composition of the ordinary Portland cement conforms to the "GB175-2007" standard.

A second aspect of the present invention provides a method for preparing a cement replacement composition, comprising mixing 50-70% by weight of cement and 30-50% by weight of a fly ash composition, wherein the fly ash composition contains Fly ash I with a D90 below 8 μm and optionally fly ash II with a D90 of greater than 8 μm and below 90 μm, and the content of fly ash I is greater than 10 wt % based on the total weight of the cement replacement composition.

According to a preferred embodiment of the present invention, the content of fly ash I is greater than 20% by weight based on the total weight of the cement replacement composition.

The third aspect of the present invention provides the application of the above-mentioned cement replacement composition as a building material.

Specifically, the application of the above-mentioned cement replacement composition as a building material can be, but not limited to, applications in roadbed filling materials, wall materials, fly ash cement, and concrete admixtures.

The present invention will be described in detail below by means of examples.

In the following examples and comparative examples,

(1) Equipment used

(a) Mixer: JJ-5, purchased from Wuxi Jianyi Instrument Machinery Co., Ltd.;

(b) All-in-one machine for compression and bending: model TYE-300D, purchased from Wuxi Jianyi Instrument Machinery Co., Ltd.;

(c) Cement concrete standard curing box: model HBY-40A, effective volume 0.4m ³ , 65×50×130cm, purchased from Wuxi Jianyi Instrument Machinery Co., Ltd.;

(d) Laser particle size analyzer: Model 2000, purchased from Malvern.

(2) The benchmark cement (ordinary Portland cement) was purchased from the Institute of Cement Science and New Building Materials Science, China Academy of Building Materials. The composition is shown in Table 1.

Table 1

composition SiO₂ TiO₂ Al₂O₃ Fe₂O₃ FeO MnO MgO CaO Na₂O K₂O P₂O₅ content% 18.31 0.24 4.35 3.26 0 0.07 1.89 66.99 0.12 0.82 0.07

(3) The fly ash raw ash was purchased from Sanhe Power Plant, a subsidiary of Shenhua Group. The composition is shown in Table 2, and the particle size distribution is shown in Table 3.

Table 2

composition SiO₂ TiO₂ Al₂O₃ Fe₂O₃ FeO MnO MgO CaO Na₂O K₂O P₂O₅ content% 48.21 1.31 32.00 5.65 0 0.12 0.90 7.86 0.81 0.24 0.39

table 3

D10(μm) D50(μm) D90(μm) Distribution range (μm) fly ash raw ash 2.180 31.609 140.545 0.209～630.957

Preparation Example 1

The fly ash raw ash is subjected to a cyclone classification method and separated by a fly ash classifier to obtain fly ash I with a D90 of less than 8 μm, and fly ash II with a D90 of greater than 8 μm and less than 90 μm. Among them, the particle size distribution of fly ash I and fly ash II was measured by a laser particle size analyzer, and the results are shown in Table 4.

Table 4

D10(μm) D50(μm) D90(μm) Distribution range (μm) Fly Ash I 0.701 2.849 5.972 0.209～13.183 Fly Ash II 6.468 29.034 83.611 0.209～158.489

Example 1

50% by weight of the benchmark cement is mixed with 50% by weight of a fly ash composition, wherein the fly ash composition contains fly ash I with a D90 of less than 8 μm and powder with a D90 of greater than 8 μm and less than 90 μm Soot II. Based on the total weight of the cement replacement composition, the content of fly ash I was 20% by weight, and the content of fly ash II was 30% by weight to obtain a cement replacement composition.

Add water to the cement replacement composition, stir it into a uniform slurry on a mixer, put the slurry on the jumping table within a specified time (2min), measure the diameter of the circle formed by the slurry, and control the fluidity to 19.5 cm, pour the sample into the triple sample mold, cure naturally, demould 24 hours after molding, put the sample into the standard curing box of cement concrete, temperature (20±1℃), humidity ≥90%, 28 days old After the period, test.

According to the national standard GB/T 17671-1999, the 28-day compressive strength was tested by the compressive and flexural integrated machine. The results are shown in Table 5.

Example 2

50% by weight of the benchmark cement is mixed with 50% by weight of a fly ash composition, wherein the fly ash composition contains fly ash I with a D90 of less than 8 μm and powder with a D90 of greater than 8 μm and less than 90 μm Soot II. Based on the total weight of the cement replacement composition, the content of fly ash I was 10 wt %, and the content of fly ash II was 40 wt % to obtain a cement replacement composition.

According to the method of Example 1, the compressive strength for 28 days was tested, and the results are shown in Table 5.

Example 3

50% by weight of the benchmark cement was mixed with 50% by weight of fly ash I to obtain a cement replacement composition.

According to the method of Example 1, the compressive strength for 28 days was tested, and the results are shown in Table 5.

Example 4

70% by weight of the benchmark cement is mixed with 30% by weight of a fly ash composition, wherein the fly ash composition contains fly ash I with a D90 of less than 8 μm and powder with a D90 of greater than 8 μm and less than 90 μm Soot II. Based on the total weight of the cement replacement composition, the content of fly ash I was 20% by weight, and the content of fly ash II was 10% by weight to obtain a cement replacement composition.

According to the method of Example 1, the compressive strength for 28 days was tested, and the results are shown in Table 5.

Example 5

70% by weight of the benchmark cement is mixed with 30% by weight of a fly ash composition, wherein the fly ash composition contains fly ash I with a D90 of less than 8 μm and powder with a D90 of greater than 8 μm and less than 90 μm Soot II. Based on the total weight of the cement replacement composition, the content of fly ash I was 10 wt %, and the content of fly ash II was 20 wt % to obtain a cement replacement composition.

According to the method of Example 1, the compressive strength for 28 days was tested, and the results are shown in Table 5.

Example 6

70% by weight of the benchmark cement was mixed with 30% by weight of fly ash I to obtain a cement replacement composition.

According to the method of Example 1, the compressive strength for 28 days was tested, and the results are shown in Table 5.

Comparative Example 1

100% by weight of the benchmark cement was used.

According to the method of Example 1, the compressive strength for 28 days was tested, and the results are shown in Table 5.

Comparative Example 2

50% by weight of the benchmark cement is mixed with 50% by weight of a fly ash composition, wherein the fly ash composition contains fly ash I with a D90 of less than 8 μm and powder with a D90 of greater than 8 μm and less than 90 μm Soot II. Based on the total weight of the cement replacement composition, the content of fly ash I was 5 wt %, and the content of fly ash II was 45 wt % to obtain a cement replacement composition.

According to the method of Example 1, the compressive strength for 28 days was tested, and the results are shown in Table 5.

Comparative Example 3

50% by weight of the benchmark cement was mixed with 50% by weight of fly ash II to obtain a cement replacement composition.

According to the method of Example 1, the compressive strength for 28 days was tested, and the results are shown in Table 5.

Comparative Example 4

50% by weight of the benchmark cement was mixed with 50% by weight of fly ash raw ash to obtain a cement replacement composition.

According to the method of Example 1, the compressive strength for 28 days was tested, and the results are shown in Table 5.

Comparative Example 5

70% by weight of the benchmark cement is mixed with 30% by weight of a fly ash composition, wherein the fly ash composition contains fly ash I with a D90 of less than 8 μm and powder with a D90 of greater than 8 μm and less than 90 μm Soot II. Based on the total weight of the cement replacement composition, the content of fly ash I was 5 wt %, and the content of fly ash II was 25 wt % to obtain a cement replacement composition.

According to the method of Example 1, the compressive strength for 28 days was tested, and the results are shown in Table 5.

table 5

In the cement replacement composition of the present invention, the mixing amount of fly ash can reach 50% by weight, and the 28-day compressive strength of the sample is comparable to that of pure cement. When the mixing amount of fly ash is controlled at 30% by weight, the 28-day compressive strength of the sample can reach 1.15 times that of pure cement.

The preferred embodiments of the present invention have been described above in detail, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, a variety of simple modifications can be made to the technical solutions of the present invention, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed in the present invention. All belong to the protection scope of the present invention.

Claims (10)

1. a kind of cement substitute composition, which is characterized in that with the total weight of cement substitute composition, contain 50-70 weight Measure % cement and 30-50 weight % fly ash composition, wherein the fly ash composition contain D90 8 μm with Under flyash I and optional D90 be greater than 8 μm and be 90 μm of flyash II below, and with the total of cement substitute composition The content of poidometer, flyash I is greater than 10 weight %.

2. cement substitute composition according to claim 1, wherein with the total weight of cement substitute composition, fine coal The content of grey I is greater than 20 weight %.

3. cement substitute composition according to claim 1 or 2, wherein the composition of flyash I and the composition of flyash II It is identical or different.

4. cement substitute composition according to claim 3, wherein contain 1-66 weight in the composition of the flyash I Measure the SiO of %₂, 0-4 weight % TiO₂, 1-41 weight % Al₂O₃, 1-7 weight % Fe₂O₃, 0-5 weight % FeO, 0- The MnO of 3 weight %₂, 1-4 weight % MgO, 1-17 weight % CaO, 0.1-5 weight % Na₂O, 0.1-5 weight % K₂O, the P of 0-3 weight %₂O₅With the SO of 0-6 weight %₃。

5. cement substitute composition according to claim 3, wherein contain 1-66 weight in the composition of the flyash II Measure the SiO of %₂, 0-4 weight % TiO₂, 1-41 weight % Al₂O₃, 1-7 weight % Fe₂O₃, 0-5 weight % FeO, 0- The MnO of 3 weight %₂, 1-4 weight % MgO, 1-17 weight % CaO, 0.1-5 weight % Na₂O, 0.1-5 weight % K₂O, the P of 0-3 weight %₂O₅With the SO of 0-6 weight %₃。

6. cement substitute composition according to claim 1, wherein the cement is ordinary portland cement, slag silicon One of acid salt cement, Portland pozzolana cement, Portland fly ash cement and composite Portland cement are a variety of.

7. cement substitute composition according to claim 6, wherein the cement is ordinary portland cement.

8. a kind of preparation method of cement substitute composition, by the flyash group of the cement of 50-70 weight % and 30-50 weight % It closes object to be mixed, wherein the fly ash composition contains D90 and is being greater than 8 in 8 μm of flyash I below and optional D90 μm and be 90 μm of flyash II below, and the content substituted with the total weight of cement substitute composition, flyash I in cement Greater than 10 weight %.

9. according to the method described in claim 8, wherein, with the total weight of cement substitute composition, the content of flyash I is big In 20 weight %.

10. application of the cement substitute composition as construction material described in any one of claim 1-7.