AU2014258397A1 - Fluidity Improvement type Cement Clinker - Google Patents

Abstract

In this Portland cement clinker, in which, as calculated by the Bogue equations, there is 50-70 mass% of C

Description

1 DESCRIPTION FLUIDITY IMPROVEMENT TYPE CEMENT CLINKER 5 TECHNICAL FIELD The present invention relates to Portland cement clinker. More specifically, it relates to cement clinker which provides a cement composition having excellent fluidity even when it has a high content of Al 2 0- derived from 10 a raw material. BACKGROUND ART Portland cement clinker is essentially composed of SiO 2 , A120 3 , CaO and Fe 2 0 3 . These components are contained in the 15 clinker as minerals. More specifically, the minerals contained in the clinker are C 3 S (3CaO-SiO 2 ), C 3 A (3CaO-Al 2 0 3 ) ,

C

2 S (2CaO-SiO 2 ) and C4AF (4CaO-Al2O 3 'Fe 2 O3), and it is well known that the existence ratio of these components has a great influence upon the physical properties of cement. 20 In the manufacturing of cement, wastes and by-products are recycled as raw materials and heat energy sources. Among the wastes and by-products which are reused in cement, there are many having a high content of an Al component (chemical species containing an aluminum atom) . Examples thereof 25 include incinerated ash of city garbage, blast furnace water granulated slag, blast furnace air-cooled slag and coal ash. When the amount of the above waste or by-product having a high content of an aluminum component is increased for the manufacturing of cement, the content of C 3 A out of the 30 Portland cement clinker components becomes high. Since this

C

3 A is a mineral which greatly contributes to initial hydration, the fluidity of the obtained cement composition becomes unsatisfactory due to an increase in the content of

C

3

A.

2 DISCLOSURE OF THE INVENTION It is preferred from the viewpoint of the effective use of resources that the amount of the waste or by-product 5 should be increased for the manufacturing of cement . However, if this exerts an adverse effect upon the workability and physical properties of the obtained cement, it is meaningless. Since the fluidity of a cement composition has a great influence upon workability, the cement composi tion must have 10 appropriate fluidity. It is therefore an object of the present invention to provide cement clinker which provides a cement composition having excellent fluidity even when the content of C3A is increased by using waste or by-product having a high content 15 of an Al component. The inventors of the present invention conducted intensive studies in view of the above problem. As a result, they found that excellent fluidity is ensured by adjusting the content of MnO even when the content of C3A out of the 20 clinker minerals is high. The present invention was accomplished based on this finding. That is, the present invention provides Portland cement clinker which contains 50 to 70 mass% of C 3 S, 10 to 20 mass% Of C2S, 10 to 15 mass% of C3A and 8 to 15 mass% of 25 C4AF all of which are calculated by Bogue' s equations and further 1.0 to 2.5 mass% of MnO. BEST MODE FOR CARRYING OUT THE INVENTION The Portland cement clinker of the present invention 30 (may also be simply referred to as "cement clinker" hereinafter) comprises 50 to 70 mass% of C3S, 10 to 20 mass% of C 2 S, 10 to 15 mass% of C 3 A and 8 to 15 mass% of C 4 AF all of which are calculated by Bogue's equations. The Bogue's equations are for the estimation of the composition of minerals in cement clinker from the analytical results of chemical composition obtained for the cement clinker and refer to the following four simultaneous equations in this text. 5 Content of C3S = (4.07 x CaO) -- (7.60 x Si0 2 ) (6.72 x A1 2 0 3 ) - (1.43 x Fe 2 0 3 ) Content of C 2 S = (2.87 x S102) - (0.754 x C 3 S) Content of C3A = (2.65 x Al20 3 ) (1.69 x Fe 2 03) Content of C4AF = 3.04 x Fe 2 0 3 10 In the above equations, the terms represented by the chemical formulas mean the contents of the species obtained by the chemical composition analysis of the cement clinker, and "C 3 S" in the second equation is the content of C 3 S estimated by the first equation. All of these are values 15 based on mass. The cement clinker of the present invention has a first feature that the content of C 3 A out of the above four minerals is not less than 10 mass% which is higher than that of normal cement clinker. Since a higher content of C 3 A than that of 20 normal cement clinker is allowed, a large amount of waste or by-product having a high content of an Al component may be used as a raw material. When the content of C 3 A in the cement clinker is higher than 15 mass%, the fluidity of the obtained cement composition greatly degrades. Even when the 25 cement clinker contains a significant amount of Mno, it is difficult to restore fluidity to such an extent that the cement clinker becomes industrially usable. The content of

C

3 A is preferably 10 to 12 mass%. The content of C 3 S is preferably 60 to 70 mass%, the 30 content of C 2 S is preferably 12 to 17 masss, and the content of C 4 AF is preferably 9 to 12 mass%. The second feature of the cement clinker of the present invention is that it contains 1.0 to 2.5 mass% of MnO. By containing MnO, the fluidity of the obtained cement 4 composition can be improved. When the content of MnO is lower than 1.0 mass%, the fluidity improving effect may become unsatisfactory. Although fluidity becomes higher as the content of MnO becomes higher, the compressive strength of 5 a hardened body tends to degrade. When the content of MnO is higher than 2.5 mass%, the reduction of compression strength may cause a practical problem. The content of MnO is preferably 1.0 to 1.5 mass%. The content of MnO in this text is not limited to the 10 content of chemical species actually existent in the form of MnO. The content of MnO in this text is a value calculated from the amount of a manganese atom determined by the chemical composition analysis of the cement clinker in terms of the mass of MnO. 15 The chemical composition analysis quantitativee analysis) of components contained in the cement clinker may be carried out in accordance with, for example, the chemical analysis method specified in JIS R 5202 or the fluorescent X-ray analysis method specified in JIS R 5204. 20 The process for manufacturing the cement clinker of the present invention is not particularly limited. The cement clinker of the present invention may be manufactured by suitably applying a conventionally known cement clinker manufacturing process except that the 25 blending ratio of known. raw materials is adjusted to ensure that the cement clinker after burning has the above mineral composition and the above content of MnO. As the raw materials whichn can be used, not only natural raw materials such as limestone, clay, silica stone and iron 30 ore but also wastes and by-products may be used. Specific examples of the wastes and the by-products include blast furnace slag, steel slag, nonferrous slag, coal ash, sewage sludge, water purification sludge, paper making sludge, construction generated soil, molding sand, dust, 5 incineration fly ash, molten fly ash, wood, waste white clay, coal refuse, waste tires, shells, city garbage and incineration ash of city garbage (some of these become the raw materials of the cement clinker and heat energy sources) . 5 Raw materials having a high content of an Al component which increases tne content of C 3 A to the above range include blast furnace slag, coal ash, paper making sludge, construction generated soil, incineration fly ash, city garbage and incineration ash of city garbage; and raw 10 materials having a high content of an Mn component (chemical species containing a manganese atom) which is used to set the content of MnO to the above range include manganese minerals and waste batteries. The Mn component contained in the raw materials is often 15 contained in a form (for example, oxide, composite oxide or alloy) having almost no volatility at a clinker burning temperature. Therefore, calculation may be carried out to determine the blending ratio based on the condition that all of manganese atoms contained in the Mn component contained 20 in the raw materials move into cement clinker. When it is known in advance that there is a Mn component which volatilizes in the raw material grinding step or burning step and is not introduced into the cement clinker, calculation must be carried out by taking this into consideration as a 25 matter of course. When calculation is carried out in accordance with a determined method for the control of composition at the time of manufacturing cement clinker, the composition of components of the cement clinker after burning can be generally controlled to a range of calculated 30 value±0.05 mass%. Cement clinker can be obtained by burning the raw materials whose blending ratio has been adjusted as described above in accordance with a determined method in the industry. The burning method is not particularly limited, and a 6 conventionally known method is suitably selected to burn the raw materials. For example, a cement kiln such as NSP kiln or SP kiln which is capable of hi gh-temperature heating is used to burn the raw materials at a temperature of 1, 450*C 5 or higher for preferably 20 to 120 minutes. The cement clinker manufactured as described above may be used as a JIS-standard cement composition, a cement composition based on standards other than JIS standards or the raw material of a cement-based solidifying agent in IC) accordance with a known method. The JIS-standard cement composition or the cement composition based on standards other than JIS standards preferably contains at least a ground product of the cement clinker manufactured as described above and a ground product 15 of gypsum. in addition to these, the composition may contain a ground product of at least one selected from blast furnace slag, limestone (calcium carbonate) , fly ash and silica fume. The content of a ground product of gypsum in the above cement composition is preferably 0. 5 to 5 parts by mass, more 20 preferably 1.5 to 3 parts by mass in terms of SO 3 based on 100 parts by mass of a ground product of the cement clinker. The preferred contents of other components based on 100 parts by mass of a ground product of the cement clinker are given below. 25 Blast furnace slag: preferably not more than 70 parts by mass, more preferably 0.5 to 60 parts by mass, much more preferably 0.5 to 30 parts by mass Limestone (calcium carbonate) : preferably not more than 30 parts by mass, more preferably 0.5 to 10 parts by mass 30 Fly ash: preferably not more than 50 parts by mass, more preferably 0.5 to 30 parts by mass Silica fume: preferably not more than 20 parts by mass, more preferably 0.5 to 10 parts by mass The above cement composition may be produced by grinding the above components after they are mixed together, mixing the components after they are each ground, or a combination of these methods. A suitable grinding aid may be added at the time of grinding. 5 The above cement composition has a Blaine specific surface area of preferably not less than a value determined by JIS standards, more preferably 2, 800 to 5, 000 cm 2 /g. This specific surface area can be achieved by suitably adjusting the degree of the above grinding. 10 The cement composition obtained as described above may be used to produce a hardened body by adding water directly or after it is mixed with a suitable material and may also be used as blast furnace slag cement or fly ash cement by mixing blast furnace slag or fly ash. 15 EXAMPLES Although the constitution and effect of the present invention will be explained with reference to the following examples, it is to be understood that the present invention 20 is not limited to these examples. The following reagents were used as the raw materials of the cement clinker in the following examples and comparative examples. CaO source: calcium carbonate (special grade) of Wako Pure 25 Chemical Industries, Ltd. Si02 source: silicon dioxide (special grade) of Wako Pure Chemical Industries, Ltd. Al 203 source: aluminum oxide (special grade) of Wako Pure Chemical Industries, Ltd. 30 Fe 2 0 3 source: iron oxide (first grade) of Wako Pure Chemical Industries, Ltd. MnO source: manganese oxide (first grade) of Wako Pure Chemical Industries, Ltd. The gypsum used to prepare the cement composition was 8 byproduct gypsum generated from a thermal power plant. Examples 1 and 2, Comparative Examples 1 and 2 and Reference Example 5 (1) Preparation and composition analysis of cement clinker The above cement composition raw materials were fed to an electric furnace and fully mixed together to ensure that the contents of C 3 S, C2S, C 3 A and C 4 AF calculated by Bogue' s equations and also the content of MnO became values 10 shown in Table I below and burned in the atmosphere at 1, 450*C for 1.5 hours to obtain cement clinker. The chemical composition obtained by fluorescent X-ray analysis based on JIS R 5204 of the cement clinker obtained above and the composition of clinker minerals obtained by 15 inserting the composition into the Bogue' s equations are shown in Table 1. (2) Preparation of cement composition and measurement of cement paste flow 20 After gypsum was added to the cement clinker obtained above to ensure that the content of SO 3 became 1. 8 to 1. 9 mass%, the resulting product was ground by using a ball mill to ensure that its Blaine specific surface area became 3,200 to 3, 300 cm 2 /g to prepare a cement composition. 25 A cement paste flow of the cement composition obtained above was measured right after kneading under the conditions of a water/cement ratio of 0.50, a kneading time of 3 minutes and a testing temperature of 20C without adding an admixture in accordance with JASS 15 M-103. The measurement results 30 are shown in Table 1.

9 U)) i i LL '9 C) C) 0 ' ci)i C (I) -2 ------ -- ou ko w 4-4 -4 43 0 Ccco io 9~i ) 0 P 0 w1 m 0) C-) 12 -o - 1 1 C) ~ OIH (l H H- - -- - -- -- -- - -- - - 00 01 LO monl Lo 0 ,--- c. _NT W 4)-C' (U' 4-) a (0 H C) x x C) Y -'-- 0 ' 1-1 0a f -4U U _ - -------- ---L --- 1 0 In Comparative Examples 1 and 2, the content of C 3 A calculated by the Bogue' s equation is high at 10 mass%. Cement paste flow values of these comparative examples are smaller than the value of the reference example in which the .5 content of CA is low. In contrast to this, in Examples 1 and 2 in which the contents of MnO are 1.0 mass% and 1.5 mass%, respectively, it is understood that even when the content of CA is high at 10 mass%, the clinker compositions show a good flow value. 10 Effect of the invention According to the present invention, even when a recycled raw material which increases the content of C 3 A in cement clinker is used, a cement composition having excellent 15 fluidity can be obtained by increasing the content of MnO in the clinker. Therefore, it is possible to use larger amounts of raw materials having a high Al content than before, thereby promoting the effective use of wastes.

Claims (2)

1. 2. A cement composition which comprises a ground product of the Portland cement clinker of claim I and a ground product 0 of gypsum.
2. 3. The cement composition according to claim 2 which further comprises a ground product of at least one selected from blast furnace slag, limestone, fly ash and silica fume.