AU785034B2

AU785034B2 - Hydrothermal solidification preparation, hydrothermally solidified material, and process for producing hydrothermally solidified material

Info

Publication number: AU785034B2
Application number: AU15023/01A
Authority: AU
Inventors: Hideki Ishida; Hiroki Maenami; Hiroto Shin; Osamu Watanabe
Original assignee: Inax Corp
Current assignee: Inax Corp
Priority date: 2000-03-17
Filing date: 2001-01-16
Publication date: 2006-08-31
Anticipated expiration: 2021-01-16
Also published as: AU1502301A; CN1314217A; CN1148269C; JP3818822B2; JP2001261388A

Description

P/00/01 1 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention title: Hydrothermal solidification preparation, hydrothermally solidified material, and process for producing hydrothermally solidified mateial The following statement is a full description of this invention, including the best method of performing it known to us: dxbm MO 114lv 0a105vI0000

SPECIFICATION

TITLE OF THE-INVENTION HYDROTHERMAL SOLIDIFICATION PREPARATION, HYDROTHERMALLY SOLIDIFIED MATERIAL, AND PROCESS FOR PRODUCING HYDROTHERMALLY SOLIDIFIED MATERIAL BACKGROUND OF THE INVENTION 1. Field of the Invention: The present invention relates to a hydrothermal solidification preparation, a hydrothermally solidified material, and a process for producing a hydrothermally solidified material.

2. Description of the Conventional Art: General hydrothermally solidifiedmaterials, which are a calcium silicate product such as ALC (autoclaved light weight concrete), were obtained from a hydrothermal solidification preparation composed mainly of a CaO component and an SiO 2 component, so as to forma calcium silicate hydrate (hereinafter referred to as such as tobermorite (5CaO- 6SiOz2-5HO) and xonotlite (6CaO 6SiO2 H 2 0) by hydrothermal processing.

In general, such a hydrothermal solidification preparation is, first of all, added with a moisture to form a slurry, which is then formed into a molding by cast molding or extrusion molding. Subsequently, this 1 molding is subjected to hydrothermal processing. The thus obtained hydrothermally solidified material is given a strength by C-S-H such as tobermorite.

Especially, a demand of reuse of inorganic industrial wastes is increasing in recent years and, for this purpose, a process for producing a hydrothermally solidified material, in which an inorganic industrial waste such as scum, glass chip, tile chip, lime ash, casting sand waste, sludge incineration ash, glazing sludge, slug, and siliceous clay is used as a part of a rawmaterial for a hydrothermal solidification preparation, and an SiOz component in the hydrothermal solidification preparation is obtained from the inorganic industrial waste (Japanese Patent No. 2,748,206, etc.), has been developed.

However, according to the production process of the conventional art as described above, even in the case where an inorganic industrial waste is used as the raw material, a large amount of the SiO, component must be contained in the hydrothermal solidification preparation. Accordingly, a raw material containing a large amount of an SiO 2 component and a small amount of an AlO 3 component had to be used. Consequently, the control of the rawmaterial and the processing conditions was complicated, and the reduction of the production 2 cost was limited.

In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date: part of common general knowledge; or (ii) known to be relevant to an attempt to solve any problem with which this specification is concerned.

SUMMARY OF THE INVENTION Under such circumstances, the present invention has been made. That is, in the production of a hydrothermally solidified material, the present invention is aimed to solve S* the problems for simplifying the control of the raw material and the processing conditions and realizing a reduction of the production cost, or to at least provide the public with o useful alternative.

So We, the present inventors made extensive and intensive investigations in order to 15 attain such aims. As a result, it has been found that a molding formed from a hydrothermal solidification preparation by cold dry-type pressure molding forms a hydrogarnet by hydrothermal processing, and this hydrogarnet can give a strength of a *hydrothermally solidified material, leading to accomplishment of the present invention.

Specifically, the hydrothermal solidification preparation according to the present invention comprises a CaO component, an SiO 2 component and an A1 2 0 3 component, which is capable of forming a hydrogarnet by forming a molding such that pores having an inner diameter of 10 Am or more account for 10% or less of the whole of pores and then subjecting it to hydrothermal processing.

Further, the hydrothermally solidified material according to the present invention comprises a CaO component, an SiO 2 component and an A1 2 0 3 component, whose strength is obtained by a hydrogarnet.

Moreover, the process for producing a hydrothermally solidified material according to the present invention comprises: a preparation step for preparing a hydrothermal solidification preparation comprising a CaO component, an SiO, component and an A12O, component; a forming step for forming the hydrothermal solidification preparation into a molded product in such a state that pores having an inner diameter of 10 Am or more occupy 10 or less of the whole of pores; and jzlm M0111867914vl 304639908 7.6.2006 4 a hydrothermal step for subjecting the molding to hydrothermal processing to obtain a hydrothermally solidified material whose strength is obtained by a hydrogarnet; and wherein the forming step is effected by press molding.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is concerned with Evaluation 1 of Test 1 and shows formation phases at the respective Al/ (Al Si) ratios and aging times; Fig 2 is concerned with Evaluation 1 of Test 1 and shows a relation between the aging time and the bending strength; Fig. 3 is concerned with Evaluation 1 of Test 1 and jzlm M0111867914vl 304639908 7.6.2006 shows an XRD chart in Hydrothermally Solidified Material No. 4; Fig. 4 is concerned with Evaluation 1 of Test 1 and shows an XRD chart in Hydrothermally Solidi.fied Material

I

No. Fig. 5 is concerned with Evaluation 2 of Test 1 and shows a relation between the aging time and the rate of reaction of the Ca source; Fig. 6 is concerned with Evaluation 2 of Test 1 and shows a relation between the aging time and the rate of reaction of the Si-Al source; Fig. 7 is concerned with Evaluation 3 of Test 1, in which is an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No. 1 aged for 2 hours, and is an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No.

1 aged for 20 hours; Fig. 8 is concerned with Evaluation 3 of Test 1, in which is an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No. 2 aged for 2 hours, and is an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No.

2 aged for 20 hours; 5 Fig. 9 is concerned with Evaluation 3 of Test 1, in which is an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No. 3 aged for 2 hours, and is an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No.

3 aged for 20 hours; Fig. 10 is concerned with Evaluation 3 of Test 1, in which is an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No. 4 aged for 2 hours, and is an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No.

4 aged for 20 hours; Fig. 11 is concerned with Evaluation 3 of Test 1, in which is an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No. 5 aged for 2 hours, and is an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No.

aged for 20 hours; Fig. 12 is concerned with Evaluation 3 of Test 1 and shows a pore size distribution of Hydrothermally Solidified Material No. 1; Fig. 13 is concerned with Evaluation 3 of Test 1 6 and shows a pore size distribution of Hydrothermally Solidified Material No. 2; Fig. 14 is concerned with Evaluation 3 of Test 1 and shows a pore size distribution of Hydrothermally Solidified Material No. 3; Fig. 15 is concerned with Evaluation 3 of Test 1 and shows a pore size distribution of Hydrothermally Solidified Material No. 4; Fig. 16 is concerned with Evaluation 3 of Test 1 and shows a pore size distribution of Hydrothermally Solidified Material No. Fig. 17 is a schematic structural drawing of Hydrothermally Solidified Materials Nos. 2 to Fig. 18 is concerned with Evaluation of Test 2 and shows a relation of the aging temperature and the aging time with the bending strength; and Fig. 19 is concerned with Evaluation of Test 2 and shows a relation of the aging temperature and the aging time with the formation phase.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, the hydrothermal solidification preparation is formed into a molding such that pores having an inner diameter of pLm or more account for 10 or less of the whole of pores, and the molding is subjected to hydrothermal 7 processing to obtain a hydrogarnet (hydrogarnet-grossularite solid solution). This hydrogarnet gives a strength of the hydrothermally solidified material. Such a hydrogarnet is expressed by C 3

ASJ-:<H

2 (wherein C is CaO; A is A10l 3 S is SiO2; H is H 2 0; and x is 0 to 3, hereinafter the same) If x is a natural number of 0 to 3, the C3AS_-xH 2 includes

C

3 AHf to C3AS 3 in which C 3 AH; (hydrogarnet), C 3

ASH

4 (katoite) C3ASzH 2 (hibschite), and C 3

AS

3 (grossularite) are known.

In the present invention, in order to obtain this hydrogarnet, the hydrothermal solidification preparation can contain an A1 2 0: component in addition to the CaO component and the SiOcomponent. Accordingly, raw materials containing theAl11 3 component can be used.

In particular, raw materials having a low SiO 2 content but a high A12O content are rich in the market, and many raw materials can be used. For this reason, it is possible to simplify the control of the raw material and the processing conditions, whereby a reduction of the production cost can be realized. Also, the possibility for reuse of inorganic industrial wastes will be increased.

Consequently, according to the present invention, not only the controlof the raw material and the processing 8 conditions can be made simple, but also a reduction of the production cost can be realized, during the production of a hydrothermally solidified material.

Further, raw materials having a high A1203 content are superior in moisture conditioning performance, resulting in enabling one to produce building materials superior in moisture conditioning performance.

According to experiments made by the present inventors, the hydrogarnet can give the strength of the hydrothermally solidified material. Further, when the hydrothermal solidification preparation has an Al/ (Al Si) ratio of 0.05 to 0.5, its hydrogarnet is formed in the hydrothermally solidified material. In this connection, AlandSimeananatomicnumber, respectively *.i (hereinafter the same). If it is possible to obtain the strength by the hydrogarnet, a change of the strength caused by a fluctuation in preparing the hydrothermal solidification preparation and a fluctuation of the processing conditions temperature, time) is relatively small, so that the merit in the production management is large.

Especially, when the Al/(A1 Si) ratio of the hydrothermal solidification preparation is 0.24 to only a hydrogarnet is formed in the hydrothermally 9 solidified material. In this case, the merit in the production management becomes the maximum.

In the present invention, it is preferred that a Ca/Si ratio is from 0.05 to 1.0. In this connection, Ca and Si mean an atomic number, respectively (hereinafter the same) Within this range, the residual amount of the unreacted CaO component can be made low, and the resulting hydrothermally solidified material has a practically useful strength.

Examples of the CaO component that can be used include quick lime and slaked lime. Examples of the SiO component that can be used include quartz and silica sand as well as siliceous waste powders such as crushed stone wastes. And, examples of the Al20j component that can be used include clay minerals such as kaolinite, mica, chlorite, and clinochlore. According to the results of tests made by the present inventors, it is preferred to use clay minerals having clay particles of, kaolinite. As the SiOZ component and the Al0.

3 component, feldspars such as orthoclase can be used.

Further, the whole of the CaO component, the SiO, component and the AlO component can also be composed of inorganic industrial wastes such as scum, glass chip, tile chip, lime ash, casting sand waste, sludge incineration ash, glazing sludge, slug, and siliceous 10 clay.

Incidentally, since even the conventional hydrothermally solidified materials could have contained the CaO component, the SiOz component and the Alz0 3 component, itmaybeconsideredthatthehydrogarnet would have been partly formed. However, in the conventional hydrothermally solidified materials, it was not considered that the hydrogarnet contributes to the obtaining of the strength. Rather, it was considered that the hydrogarnet generates defects in the hydrothermally solidified material. According to the consideration of the present inventors, the reasons for this are as follows. That is, in the conventional production processes, the hydrothermal solidification preparation is used as a slurry, and a molding obtained from this slurry is subjected to hydrothermal processing.

In this case, in the molding, the raw material particles are filled merely at a low density, and the respective particles should retain large voids each other. Thus, it is considered that if the hydrogarnet is formed in this state, the hydrogarnet becomes a large crystal, and the crystals are hardly bound to each other, whereby the strength is not obtained. Further, it is considered that the large crystal generates a strain among the particles, thereby rather generating defects in the 11 hydrothermally solidified material.

In contrast, in the present invention, the hydrogarnet is formed in a molding formed such that pores having an inner diameter of 10 Lm or more account for or less of the whole of pores. According to experiments made by the present inventors, by such forming, the raw material particles are filled at a high density, and the respective particles retain small voids each other, as compared with the molding from the slurry.

Thus, it is considered that if the hydrogarnet is formed in this state, the hydrogarnet becomes a fine crystal, and the crystals are readily bound to each other, whereby the strength is obtained. According toexperimentsmade by the present inventors, it is more preferred to effect ".ithe forming such that pores having an inner diameter of 10 pm or more account for 3 or less of the whole of pores.

The forming can be effected by press molding. As the press molding, in addition to cold dry-type pressure molding, CIPmolding, HIPmolding, Doctor blade molding, etc. can be used. Further, the forming may be effected by cast molding, pour molding such that pores having an inner diameter of 10 um or more account for 10 or less, and preferably 3 or less of the whole of pores.

12 According to the confirmation made by the present inventors, it is considered that in the hydrothermally solidified material containing clay particles, while the clay particles retain voids each other depending upon a difference in filling properties or a difference of the elution behavior of the A1 2 0 3 component, the particles are bound via the hydrogarnet having pores smaller than the voids. These voids are considered to have a peak in the vicinity of about 0.04 prm of the inner diameter.

The present invention will be described in detail with reference to Tests 1 to 3, while referring to the drawings.

Test 1: First of all, quick lime (CaO) as a CaO component, which is obtained by calcining calcium carbonate (CaCO 3 a reagent special grade made by Wako Pure Chemical Industries, Ltd.) at 1,000 °C for about 5 hours, a quartz powder (Indian quartz, CMC-12-S, made by Tatsumori Co., SLtd.; mean particle size: 6.8 prm, specific surface area: 1 .85 as an SiOz component, and kaolinite (Hydorite PXN, made by Dry Branch Kaolin Company (Georgia kaolin); mean particle size: 1.7 pm, specific surface area: 15.8 mZ/g) as an A_10 3 component are prepared. A chemical 13 composition (mass ratio) of the quartz powder and the kaolinite is shown in Table 1.

Table 1 SiO 2 A1 2 0 Fe 2 O CaO MgO K 2 0 NazO TiO 2

LOI

3 3 Quartz 99.5 powder Kaolinie 45.4 39.2 0.6 0.1 0.1 0.1 0.1 1.4 13.

(Preparation step) The quick lime, the quartz powder and the kaolinite are weighed and mixed such that an Al/ (Al Si) ratio is 0, 0.05, 0.24, 0.45, or 0.5, and a Ca/Si ratio is constantly 0.21, to obtain Hydrothermal Solidification Preparations Nos. 1 to In this case, with respect to the compounding amount of the quick lime, in the case where the A1/(Al Si) ratio is 0.5, the Ca/Si ratio is 0.5, and the Ca/(Al Si) ratio is 0.25. Thus, in the respective Hydrothermal Solidification Preparations Nos. 1 to the Ca/ (Al Si) ratio is 0.23 to 0.25, and the A1/(Al Si) ratio is 0 to 0.5. The compounding rate of the S9 quick lime, the quartz powder and the kaolinite in each of Hydrothermal Solidification Preparations Nos. 1 to is shown in Table 2. In Table 2, K and Q mean kaolinite and quartz, respectively.

14 Table 2 Al/(A1+ Ca/Si Ca/(Si+ SiO 2 A1 2 0 3 CaO No. (mass Si) Al) ratiol (atomic (atomic (atomic by by by ratio) ratio) ratio) mass) mass) mass) 1 0.0 0.0 0.23 0.23 82.6 0.0 17.4 2 0.1 0.05 0.24 0.23 79.1 3.3 17.6 3 0.5 0.24 0.31 0.24 64.2 17.2 19.6 4 0.9 0.45 0.45 0.24 47.4 32.9 19.7 1.0 0.50 0.50 0.25 42.9 37.1 20.0 (Forming step) Distilled water necessary for the digestion of the quick lime and distilled water of 10 by mass necessary for the forming are added to each of Hydrothermal Solidification Preparations Nos. 1 to 5, followed by cold dry-type uniaxial pressure forming at a forming pressure of 30 MPa to obtain Moldings Nos. 1 to 5 having a rectangular parallelepiped shape of 10 mm x 15 mm x 40 mm.

(Hydrothermal step) Each of Moldings Nos. 1 to 5 is charged in an autoclave device and subjected to hydrothermal processing at 200 *C for an aging time of from 2 to 20 hours under a saturated water vapor pressure, to obtain Hydrothermally Solidified Materials Nos. 1 to 15 (Evaluation 1) With respect to each of Hydrothermally Solidified Materials Nos. 1 to 5, which had been dried at 80 OC for about 2 days after the hydrothermal processing, the confirmation of a formation phase caused by an increase of the aging time and the measurement of a bending strength (MPa) and a bulk density (g/cm 3 were carried out. The confirmation of a formation phase was carried out by XRD using a powder X-ray diffraction device (RIGAKU, RAD-B) The measurement of a bending strength was carried out by a three-point bending testing method at a distance of supporting points of 30 mm at a cross head speed of 0.5 mm/min. by using a material testing machine (manufactured by A D, TENSILON RTM-500).

A formation phase at each Al/(Al Si) ratio and aging time is shown in Fig. 1. In Fig. 1, 0 means hydrogarnet; A means tobermorite; A means gyrolite (8CaO 12Si0 9HO) and O means C-S-H, respectively.

It is understood from Fig. 1 that in Hydrothermally Solidified Material No. 1 having an Al/(Al Si) ratio of 0, when the aging time is 2 hours, a C-S-H gel is formed, and when the aging time is 5 hours or more, the co-presence of gyrolite is observed; and that in Hydrothermally Solidified Material No. 2 having an 16 Al/(Al Si) ratio of 0.05, when the aging time is 2 hours, a C-S-H gel is formed, and when the aging time is 5 hours or more, this C-S-H gel is crystallized, and tobermorite is formed.

On the other hand, in Hydrothermally Solidified Materials Nos. 2 to 5 having kaolinite compounded therewith, it is understood that a hydrogarnet is formed regardless of the aging time. In other words, when the Al/(Al Si) ratio is from 0.05 to 0.5, a hydrogarnet is formed regardless of the aging time. In particular, inHydrothermallySolidifiedMaterials Nos. 3 to 5 having an Al/(Al Si) ratio of 0.24 to 0.5, only a hydrogarnet is formed, but the formation of C-S-H is not observed.

Further, the relation between the aging time and Sthe bending strength is shown in Fig. 2. In Fig. 2, 0 refers to Hydrothermally Solidified Material No. 1 having an Al/(Al Si) ratio of 0; 0 refers to Hydrothermally Solidified Material No. 2 having an [l A1/(Al Si) ratio of 0.05; A refers to Hydrothermally Solidified Material No. 3 having an A (Al Si) ratio of 0.24; A refers toHydrothermallySolidified Material No. 4 having an A (Al Si) ratio of 0.45; and V refers to Hydrothermally Solidified Material No. 5 having an Al/(Al Si) ratio of 0.5, respectively.

17 It is understood from Fig. 2 that in all of Hydrothermally Solidified Materials Nos. 1 to 5, the strength increases. Further, in Hydrothermally Solidified Materials Nos. 1 and 2 having an Al/(Al Si) ratio of 0 and 0.05, respectively, in which a C-S-H gel or tobermorite is formed, when the aging time is within 2 to 5 hours, they reach a maximum bending strength ofabout 30MPa, andthereafter, a reductionofthebending strength is observed. In particular, inHydrothermally Solidified Material No. 1 having an Al/(Al Si) ratio of 0, this tendency is remarkable. It is considered that this is caused due to the formation of gyrolite.

On the other hand, in Hydrothermally Solidified T1 Materials Nos. 2 to 5 having an A/ (Al Si) ratio of 0.05to0.5, inwhich a hydrogarnet is formed, thestrength increases, too. When the aging time is 2 hours, they reach a bending strength of about 15 to 20 MPa, and thereafter, the strength increases with an increase of the aging time. Further, even in Hydrothermally Solidified Materials Nos. 3 to 5 having an Al/(Al Si) ratio of 0.24 to 0.5, the strength increases. For this reason, it is understood that the hydrogarnet can give the strength of the hydrothermally solidified material.

In this case, it is understood that among Hydrothermally Solidified Materials Nos. 2 to 5, each 18 of which forms a hydrogarnet, Hydrothermally Solidified Material No. 2 having an Al/(Al Si) ratio of 0.05 exhibits amaximumbending strength, in which the bending strength decreases with an increase of the Al/ (Al Si) ratio. However, in the case where the Al/ (Al Si) ratio increases from 0.05 to 0.24, the bending strength is lowered by about 30 from 29.7 MPa to 20.9 MPa, whereas in the case where the Al/ (Al Si) ratio increases from 0.24 to 0.5, the bending strength is lowered merely by about 17 from 20.9 MPa to 17.4 MPa. In other words, when the Al/ (Al Si) ratio is 0.24 or more, a reduction in the rate of reduction of the bending strength is observed. Accordingly, it is understood that in the case where the A1/(Al Si) ratio is 0.24 to 0.5, a fluctuation width of the maximum bending strength by a fluctuation of the content of the Al 2 0 3 component is smaller than that in the case where the Al/(Al Si) ratio is 0.05 to 0.24.

Moreover, an XRD chart in Hydrothermally Solidified Material No. 3 having an Al/(Al Si) ratio of 0.24 is shown in Fig. 3, and an XRD chart in Hydrothermally Solidified Material No. 5 having an Al/ (Al Si) ratio of 0.5 is shown in Fig. 4. In these figures, 0 refers to kaolinite; V refers to portlandite (Ca (OH) V 19 refers to quartz (SiO 2 refers to calcite (CaCO) and 0 refers to hydrogarnet, respectively. Further, in Figs. 3 and 4, the aging time is changed at 0 hour, 2 hours, 5 hours, 10 hours, and 20 hours, respectively.

In Figs. 3 and 4, in the case where the aging time is 2 hours or more, when the Al/(Al Si) ratio is 0.24 to 0.5, anincreaseofthebendingstrengthbytheincrease of the aging time is not observed. Such is corresponding to the tendency that the peak strength of the hydrogarnet in the XRD chart did not substantially change by the aging time.

Itisunderstood fromEvaluation 1 as described above that the hydrogarnet can give the strength of the hydrothermally solidified material. Further, it is understood that when the Al/(Al Si) ratio is 0.05 to 0.5, its hydrogarnet is formed, and especially, when the Al/(Al Si) ratio is 0.24 to 0.5, only a hydrogarnet is formed. Accordingly, it can be understood that since Sthe strength can be obtained by the hydrogarnet, a change of the strength caused by a fluctuation in preparing the hydrothermal solidification preparation and a fluctuation of the processing conditions temperature, time) is relativelysmall, so that the merit in the production management is large.

20 (Evaluation 2) With respect to each of Hydrothermally Solidified Materials Nos. 1 to 5 as evaluated in Evaluation 1, the rateof reaction bymass) of the Ca source is calculated from the amount of unreacted Ca(OH), measured by TGA (RIGAKU, TAS-300) The relation between the aging time and the rate of reaction of the Ca source is shown in Fig. Further, with respect to each of Hydrothermally Solidified Materials Nos. 1 to 5, the rate of reaction by mass) of the Si-Al source is calculated from the amount of the unreacted Si-Al source obtained regarding the mass of the residue by elution processing with an aqueous 1.2 Nhydrochloric acid solution (95 C x 10 min.) *e 0 and an aqueous 5 Na 2 C0 3 solution (95 °C x 15 min.).

Se

S**

The relation between the aging time and the rate of reaction of the Si-Al source is shown in Fig. 6.

It is understood from Fig. 5 that the rate of reaction O* O of the Ca source increases with an increase of the aging time. Especially, when the aging time is up to 2 hours,

S

9* the rate of reaction of the Ca source greatly increases, and thereafter, it gradually increases.

Further, it is understood that the rate of reaction of the Ca source is lowered with an increase of the Al/ (Al 21 Si) ratio. Especially, it is understood that in Hydrothermally Solidified Materials Nos. 1 and 2 having an Al/(Al Si) ratio of from 0 to 0.05, the rate of reaction of the Ca source reaches 100 by mass, and when the aging time is 5 hours or more, almost all of the CaO component is reacted and consumed. On the other hand, it is understood that in Hydrothermally Solidified Materials Nos. 3, 4 and 5 having an Al/(Al Si) ratio is 0.24 to 0.5, the rate of reaction of the Ca source is limited to 50 to 75 by mass, and even when the aging time is 20 hours, the unreacted CaO component remains.

Moreover, it is understood from Fig. 6 that the rate of reaction of the Si-Al source increases with an increase of the aging time, likewise the rate of reaction of the Ca source. Especially, when the aging time is up to 2 hours, the rate of reaction of the Si-Al source greatly increases, and thereafter, it gradually increases.

The reason why the reaction is limited in Hydrothermally Solidified Materials Nos. 3, 4 and having an Al/(Al Si) of 0.24 to 0.5, is assumed to be corresponding to the matter that the hydrogarnet is a main formation phase. That is, there is a possibility that the hydrogarnet formed at an aging time of 2 hours inhibits a subsequent reaction of the CaO component with the SiO, component and the Al20 3 component. Then, it 22 may be considered that the limitation of the reaction causes a reduction of the maximum bending strength by about 30 (Evaluation 3) In addition, with respect to each of Hydrothermally Solidified Materials Nos. 1 to 5 as evaluated in Evaluations 1 and 2, its fine structure was evaluated by means of an SEM observation device (JEOL, JSM-5400) and a pore size distribution measurement device by a mercury charging process under pressure (Quantachrome, Autoscan-33).

magnification Solidified Mate Fig. and magnification Solidified Mate in Fig. 7(B).

magnification Solidified Mate Fig. and magnification Solidified Mate in Fig. 8(B).

magnification rial No. 1 aged for an SEM observation of 7,500 times rial No. 1 aged fo] An SEM observation of 7,500 times rial No. 2 aged for an SEM observation of 7,500 times rial No. 2 aged for An SEM observation 2 hours is shown in photograph with a of Hydrothermally S20 hours is shown photograph with a of Hydrothermally 2 hours is shown in photograph with a of Hydrothermally 20 hours is shown photograph with a An SEM observation photograph with a of 7,500 times of Hydrothermally of 7,500 times of Hydrothermally Solidified Material No. 3 aged for 2 hours is shown in 23 Fig. and an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No. 3 aged for 20 hours is shown in Fig. An SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No. 4 aged for 2 hours is shown in Fig. 10(A), and an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No. 4 aged for 20 hours is shown in Fig. 10(B). An SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No. 5 aged for 2 hours is shown in Fig. 11(A), and an SEM observation photograph with a magnification of 7,500 times of Hydrothermally Solidified Material No. 5 aged for 20 hours is shown in Fig. 11(B). Further, a pore size distribution of Hydrothermally Solidified Material No. 1 is shown in Fig. 12; a pore size distribution of Hydrothermally Solidified Material No. 2 is shown in Fig. 13; a pore size distribution of Hydrothermally Solidified Material No. 3 is shown in Fig. 14; a pore size distribution of Hydrothermally Solidified Material No. 4 is shown in Fig. 15; and a pore size distribution of Hydrothermally Solidified Material No. 5 is shown in Fig. 16, respectively. In Figs. 12 to 16, the aging time is 2 A changed at 0 hour, 2 hours, 5 hours, 10 hours, and hours, respectively.

As shown in Figs. 7 and 8, it is understood that in Hydrothermally Solidified Materials Nos. 1 and 2 having an Al/ (Al Si) ratio of 0 to 0.05, when the aging time is 2 hours or more, the formation of needle-like, network-like, or plate-like products is found among the raw material particles, and these products are filled in spacesamongtherespectiveparticles. 'phe structure found in the spaces among the respective particles is considered to be the C-S-H gel or tobermorite. In Hydrothermally Solidified Material No. 1 having an Al/(Al Si) of 0, the formation of large plate-like crystals having a size of about several p m was found .due to hydrothermal processing over a long period of time. These plate-like crystals are considered to be gyrolite. In these Hydrothermally Solidified MaterialsNos. land2, itisconsideredthatthisgyrolite causes a reduction of the strength due to the long aging i time.

Further, as shown in Fig. 9, in Hydrothermally Solidified Material No. 3 having an A (Al Si) ratio of 0.24, the formation of a very slight amount of needle-like crystals is also found. While these crystals are not detected by the XRD, they are considered 25 to be crystals of C-S-H.

Moreover, as shown in Figs. 10 and 11, in Hydrothermally Solidified Materials Nos. 4 and 5 having an Al/(Al Si) ratio of 0.45 to 0.5, the formation of only plate-like clay particles of kaolinite was found.

In this connection, according to Figs. 12 to when the aging time is 0 hour, the pore size has a peak within a range of 0.1 to 1 tim. Further, as the Al/(Al Si) ratio increases, the peak of the pore s ze is shifted to a finer side. It is considered that this peak shows a void formed by the clay particles during the forming.

And, according to Figs. 12 to 14, in Hydrothermally Solidified Materials Nos. 1 to 3 having an Al/ (Al Si) ratio of 0 to 0.24, not only the peak caused by the void among the clay particles is shifted to a finer side with a lapse of the aging time, but also the peak is made in the vicinity of 0.01 However, according to Fig.

12, in Hydrothermally Solidified Material No. 1 having an A/ (Al Si) of 0, the peak made in the vicinity of 0.01 im at an aging time.of 2 hours is shifted to a coarse side when the aging time is 5 hours or more. This shift of the pores to a coarse side is caused due to the formation of gyrolite and exhibits a reduction of the strength.

Further, the pores in the vicinity of 0.01 am in 26 Hydrothermally SolidifiedMaterialsNos. land2having an Al/(Al Si) ratio of 0 to 0.05 as shown in Figs.

12 and 13 are caused due to the formation of the C-S-H gel or tobermorite, and it is considered that this contributes to the strength to be obtained.

On the other hand, according to Figs. 15 and 16, in Hydrothermally Solidified Materials Nos. 4 and having an Al/(Al Si) ratio of 0.45 to 0.5, the shift of the peak of pores to a finer side caused with a lapse of the aging time as observed in Hydrothermally Solidified Materials Nos. 1 to 3 is not found at all.

Further, the peak of pores is lowered to about 1/2 to 2/3 times at an aging time of 2 hours. Thereafter, the peak of pores is lowered slightly in accordance with 9 i a lapse of the aging time, but it remains even at an *99* aging time of 20 hours. And, a peak of pores is newly found in the vicinity of 0.04 pm. Since the formation phase is only the hydrogarnet, it is considered that the formation of new pores is a change caused due to this, and it may be assumed that the formation of these new pores contributes to the strength to be obtained.

For these reasons, as shown in Fig. 17, it is considered that in Hydrothermally Solidified Materials Nos. 2 to 5, whilerespectiveclayparticles lof kaolinite retain voids 2 formed among them, they are more readily 27 bound by a hydrogarnet 3 having minute pores 3a in a size finer than the voids 2 due to a reaction with the CaO component. It is considered that such a phenomenon is caused as follows. That is, in Hydrothermally Solidified Materials Nos. 2 to 5, Moldings Nos. 4 and in which the clay particles 1 are filled at a high densitybycolddry-typepressure molding are used. For this reason, the respective clay particles 1 retain the small voids 2 each other as compared with a molding made of a slurry, and the hydrogarnet 3 is formed in this state. Accordingly, this hydrogarnet 3 forms fine crystals, and these crystals are readily bound to each other. In Hydrothermally Solidified Materials Nos. 4 and 5, this tendency is particularly large. The reason why the amount of the hydrogarnet formed did not increase at an aging time of 2 hours or more is considered as follows. The surfaces of the clay particles 1 were covered with the minute hydrogarnet, and the reaction had to move to the diffusion control. Thus, it is considered that the strength of Hydrothermally Solidified Materials Nos. 2 to 5 was obtained.

Test 2: Next, slaked lime (industrial slaked lime of a super-special grade, made of Ube Material Industries, Ltd.) as a CaO component and a crushed stone waste 28 (produced in Tochigi Prefecture) as an SiO2 component and an Al20 3 component are prepared. A chemical composition by mass) of the crushed stone waste is shown in Table 3.

Table 3 SiO 2 Al203 Fe20 3 CaO MgO K 2 0 Na20 TiO 2

LOI

Crushed 82.0 7.5 4.0 0.2 1.1 2.0 0.3 0.4 1.9 stone waste The crushed stone waste has an Al/(Al Si) ratio of 0.06. Further, a mineral compositionof this crushed stone waste consists of 67 by mass of quartz, 22 by mass of clay minerals including mica, chlorite and kaolinite, 7 by mass of orthoclase, and 4 9 by mass of others. And, this crushed stone waste has a mean particle size of 32.6 pm and a specific surface area of 6.08 m2/g.

(Preparation step) 80y by mass of the crushed stone waste and 20 V by mass of slaked lime are weighed and mixed to obtain Hydrothermal Solidification Preparation No. 6. Thus, Hydrothermal Solidification Preparation No. 6 has a Ca/(Al Si) ratio of 0.23.

(Forming step) Hydrothermal Solidification Preparation No. 6 29 having a water content of 9 by mass is subjected to cold dry-type uniaxial pressure forming at a forming pressure of 30 MPa to obtain Molding No. 6 having a tile shape of 110 mm x 110 mm x 15 mm.

(Hydrothermal step) Molding No. 6 is charged in an autoclave device and subjected to hydrothermal processing at 160 to 180 °C for an aging time of 2 to 40 hours under a saturated water vapor pressure, to obtain Hydrothermally Solidified Material No. 6.

(Evaluation) With respect to Hydrothermally Solidified Material No. 6, which had been dried at 80 OC for about 2 days after the hydrothermal processing, the measurement of a bending strength (MPa) and the confirmation of a formation phase caused by an increase of the aging time were carried out. The measurement of a bending strength was carried out by a three-point bending testing method at a distance of supporting points of 90 mm at a cross head speed of 2 mm/min. (n 5) by using a material testing machine (manufactured by A D, TENSILON UTM-I-2-500) A relation of the aging temperature and the aging time with the bending strength is shown in Fig. 18 and in Table 4. In Fig. 18, refers to Hydrothermally 30 Solidified Material No. 6 at an aging temperature of 160 OC; O refers to Hydrothermally Solidified Material No. 6 at an aging temperature of 170 OC; and A refers to Hydrothermally Solidified Material No. 6 at an aging temperature of 180 oC, respectively. Further, a relation of the aging temperature and the aging time with the formation phase is shown in Fig. 19.

Table 4 Aging time Aging temperature (hour) 160 170 180 2 9.3 11.6 14.5 11.3 15.6 16.3 13.5 16.1 19.6 17.3 22.7 22.4 19.9 21.6 26.5 It is evident from the foregoing that inorganic industrial wastes can be reused. Further, it is understood from Fig. 18 andTable 4 that inHydrothermally Solidified Material No. 6, the bending strength is improved with an increase of the aging temperature or the aging time. Moreover, it is understood that as the aging temperature is lower, the katoite of the hydrogarnet is more readily formed in a stable manner, regardless of the aging time; and that as the aging temperature is higher, the katoite of the hydrogarnet r 31 is more readily formed within a short aging time.

Test 3: With respect to each of Moldings Nos. 1 to 5 of Test 1, Molding No. 6 of Test 2, Molding No. 7 obtained by forming Hydrothermal Solidification Preparation No. 6 of Test 2 at 15 MPa, Molding No. 8 obtained by forming Hydrothermal Solidification Preparation No. 6 of Test 2 at 10 MPa, and a commercially available concrete as Comparative Example, a rate of pores having an inner diameter of 10 pm or more was obtained. The results are shown in Table Table No. Forming pressure Rate (MPa) 1 30 2 30 2.8 Test 1 3 30 0.6 4 30 0.4 30 6 30 Test 2 7 15 2.7 8 10 5.2 Comparative 46.6 Example It is understood from the above-described Evaluation and Table 5 that when a hydrothermal

S

**S.S

32 solidification preparation is formed by press molding such that pores having an inner diameter of 10 Am or more account for 10% or less of the whole of pores, a strength is obtained. In particular, when a hydrothermal solidification preparation is formed such that pores having an inner diameter of 10 Am or more account for 3 or less of the whole of pores, a higher strength is obtained.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

The word 'comprising' and forms of the word 'comprising' as used in this description and in the claims do not limit the invention claimed to exclude any variants or additions. Modifications and improvements to the invention will be readily apparent to those skilled in the art. Such modifications and improvements are intended to be within the scope of this invention.

o jzlm MO111867914vl 304639908 7.6.2006

Claims

1. A process for producing a hydrothermally solidified material, which comprises: a preparation step for preparing a hydrothermal solidification preparation comprising a CaO component, an SiO, component and an A1 2 O0 component; a forming step for forming the hydrothermal solidification preparation into a molded product in such a state that pores having an inner diameter of 10 pm or more occupy 10% or less of the whole of pores; a hydrothermal step for subjecting the molding to hydrothermal processing to obtain a hydrothermally solidified material whose strength is obtained by a hydrogarnet; and wherein the forming step is effected by press molding.

2. The process for producing a hydrothermally solidified material as claimed in claim 1, wherein in the preparation step, the hydrothermal solidification preparation has an Al/(Al Si) atomic ratio in the range of from 0.05 to

3. The process for producing a hydrothermally solidified material as claimed in 15 claim 2, wherein the Al/(A1 +Si) atomic ratio is in the range of from 0.24 to The process for producing a hydrothermally solidified material as claimed in any S* one of claims 1 to 3, wherein a Ca/Si atomic ratio is in the range of from 0.05 to A process for producing a hydrothermally solidified material, substantially as 20 herein described with reference to any one of Figures 1-19.

6. The process of any one of claims 1-4, substantially as herein described with reference to anyone of Figures 1-19. INAX CORPORATION 14 July 2006 z* *86791 3046 147.2006 jzlm M011"867914vl 30463'5)908 14.7.2006 14/07 2006 FRI 16:05 [TX/RX NO 7049] 0004