JP7357097B1 - Soil improvement materials and solidification treatment methods - Google Patents
Soil improvement materials and solidification treatment methods Download PDFInfo
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- 239000000463 material Substances 0.000 title claims abstract description 100
- 239000002689 soil Substances 0.000 title claims abstract description 89
- 238000007711 solidification Methods 0.000 title claims abstract description 23
- 230000008023 solidification Effects 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 title claims abstract description 22
- 239000004568 cement Substances 0.000 claims abstract description 75
- 239000003516 soil conditioner Substances 0.000 claims abstract description 38
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 25
- 230000004580 weight loss Effects 0.000 claims abstract description 22
- 239000000843 powder Substances 0.000 claims abstract description 19
- 239000002002 slurry Substances 0.000 claims abstract description 12
- 238000010438 heat treatment Methods 0.000 claims abstract description 8
- 239000010440 gypsum Substances 0.000 claims description 22
- 229910052602 gypsum Inorganic materials 0.000 claims description 22
- 239000002893 slag Substances 0.000 claims description 18
- 239000007787 solid Substances 0.000 claims description 10
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 4
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 claims description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 4
- 150000008064 anhydrides Chemical class 0.000 claims description 3
- 238000010586 diagram Methods 0.000 abstract 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- 239000011398 Portland cement Substances 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 239000013585 weight reducing agent Substances 0.000 description 11
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 4
- 239000011400 blast furnace cement Substances 0.000 description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 3
- 239000011575 calcium Substances 0.000 description 3
- 229910052791 calcium Inorganic materials 0.000 description 3
- 239000001110 calcium chloride Substances 0.000 description 3
- 229910001628 calcium chloride Inorganic materials 0.000 description 3
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 3
- 239000000920 calcium hydroxide Substances 0.000 description 3
- 235000011116 calcium hydroxide Nutrition 0.000 description 3
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 3
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 3
- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical compound [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 150000004683 dihydrates Chemical class 0.000 description 3
- 238000006703 hydration reaction Methods 0.000 description 3
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- ZMZDMBWJUHKJPS-UHFFFAOYSA-M Thiocyanate anion Chemical compound [S-]C#N ZMZDMBWJUHKJPS-UHFFFAOYSA-M 0.000 description 2
- 229910052925 anhydrite Inorganic materials 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000004455 differential thermal analysis Methods 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000011790 ferrous sulphate Substances 0.000 description 2
- 235000003891 ferrous sulphate Nutrition 0.000 description 2
- 239000010881 fly ash Substances 0.000 description 2
- ZMZDMBWJUHKJPS-UHFFFAOYSA-N hydrogen thiocyanate Natural products SC#N ZMZDMBWJUHKJPS-UHFFFAOYSA-N 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- RAFRTSDUWORDLA-UHFFFAOYSA-N phenyl 3-chloropropanoate Chemical compound ClCCC(=O)OC1=CC=CC=C1 RAFRTSDUWORDLA-UHFFFAOYSA-N 0.000 description 2
- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Chemical compound [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- DHCDFWKWKRSZHF-UHFFFAOYSA-N sulfurothioic S-acid Chemical compound OS(O)(=O)=S DHCDFWKWKRSZHF-UHFFFAOYSA-N 0.000 description 2
- OWRCNXZUPFZXOS-UHFFFAOYSA-N 1,3-diphenylguanidine Chemical compound C=1C=CC=CC=1NC(=N)NC1=CC=CC=C1 OWRCNXZUPFZXOS-UHFFFAOYSA-N 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- VEUACKUBDLVUAC-UHFFFAOYSA-N [Na].[Ca] Chemical compound [Na].[Ca] VEUACKUBDLVUAC-UHFFFAOYSA-N 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- USOPFYZPGZGBEB-UHFFFAOYSA-N calcium lithium Chemical compound [Li].[Ca] USOPFYZPGZGBEB-UHFFFAOYSA-N 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- 235000012255 calcium oxide Nutrition 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000012669 compression test Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 150000004677 hydrates Chemical class 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 239000012254 powdered material Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 229910021487 silica fume Inorganic materials 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910001388 sodium aluminate Inorganic materials 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 235000010288 sodium nitrite Nutrition 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Abstract
【課題】材料として含まれるセメント系固化材が風化している場合であっても、強度発現性に優れた土質改良材及び固化処理方法を提供することである。【解決手段】セメント系固化材と硬化促進剤を含む土質改良材であって、上記セメント系固化材が、該セメント系固化材を、昇温速度が１０℃／分で、８００℃になるまで昇温した場合における２００～８００℃の重量減少率が１．０～５．０％であるものであり、かつ、上記土質改良材が、粉体又はスラリーである土質改良材。未改良土に対して、上記土質改良材を添加し、混合して固化改良土を得る固化処理方法。【選択図】なしAn object of the present invention is to provide a soil improvement material and a solidification treatment method that exhibit excellent strength development even when the cementitious solidification material contained in the material is weathered. [Solution] A soil conditioner containing a cement-based solidifying agent and a hardening accelerator, wherein the cement-based solidifying agent cools the cement-based solidifying agent at a heating rate of 10°C/min until the temperature reaches 800°C. A soil improvement material having a weight loss rate of 1.0 to 5.0% at 200 to 800°C when the temperature is increased, and the soil improvement material is a powder or slurry. A solidification treatment method in which the above-mentioned soil conditioner is added to unimproved soil and mixed to obtain solidified improved soil. [Selection diagram] None
Description
本発明は、土質改良材及び固化処理方法に関する。 The present invention relates to a soil improvement material and a solidification treatment method.
従来、様々な土質改良材が提案されている。
例えば、熱帯性泥炭等の高有機質土、マリンクレイ等の高含水土等の各種土質の固化、改良処理に使用するセメント系固化材として、例えば、特許文献１には、普通セメント、高炉セメント、早強セメント、アーウイン系セメントの１種または２種以上を１００重量部および石膏を３～１００重量部含むことを特徴とするセメント系固化材が記載されている。
また、特許文献２には、カルシウムアルミネートを１０重量％以上含みかつ、３ＣａＯ・ＳｉＯ２を５～２０重量％含有することを特徴とする地盤改良材が記載されている。
さらに、特許文献３には、比表面積が３，０００～５，５００ｃｍ2／ｇのポルトランドセメント２０～４０重量％と、比表面積が４，０００～１０，０００ｃｍ2／ｇの高炉スラグ微粉末６０～４０重量％と、比表面積が３，０００～７，０００ｃｍ2／ｇの石膏１０～３０重量％と、からなる有機質土用セメント系固化材が記載されている。
Conventionally, various soil improvement materials have been proposed.
For example, Patent Document 1 describes ordinary cement , blast furnace cement, A cementitious solidifying material is described which is characterized by containing 100 parts by weight of one or more of early strength cement and irwin type cement and 3 to 100 parts by weight of gypsum.
Furthermore, Patent Document 2 describes a ground improvement material characterized by containing 10% by weight or more of calcium aluminate and 5 to 20% by weight of 3CaO.SiO 2 .
Furthermore, Patent Document 3 describes 20 to 40% by weight of Portland cement with a specific surface area of 3,000 to 5,500 cm 2 /g and pulverized blast furnace slag powder 60 with a specific surface area of 4,000 to 10,000 cm 2 /g. A cement-based solidifying material for organic soil is described, which comprises 10 to 30 weight % of gypsum having a specific surface area of 3,000 to 7,000 cm 2 /g.
セメント系固化材が長期に亘って保管されていた場合等において、セメント系固化材が風化している場合（具体的には、セメント系固化材の一部が、セメントの水和反応に寄与しない炭酸カルシウムや水酸化カルシウムに変化している場合）、セメント系固化材の強度発現性が低下するという問題がある。
本発明の目的は、材料として含まれるセメント系固化材が風化している場合であっても、強度発現性に優れた土質改良材及び固化処理方法を提供することである。
In cases where the cement-based solidifying material has been stored for a long period of time, and the cement-based solidifying material has weathered (specifically, some of the cement-based solidifying material does not contribute to the hydration reaction of cement). (in the case of calcium carbonate or calcium hydroxide), there is a problem that the strength development of the cement-based solidifying agent decreases.
An object of the present invention is to provide a soil improvement material and a solidification treatment method that exhibit excellent strength development even when the cementitious solidification material contained in the material is weathered.
本発明者は、上記課題を解決するために鋭意検討した結果、昇温速度が１０℃／分で、８００℃になるまで昇温した場合における２００～８００℃の重量減少率が１．０～５．０％であるセメント系固化材と、硬化促進剤を含み、かつ、粉体又はスラリーである土質改良材によれば、上記目的を達成できることを見出し、本発明を完成した。
すなわち、本発明は、以下の［１］～［６］を提供するものである。
［１］ セメント系固化材と硬化促進剤を含む土質改良材であって、上記セメント系固化材が、該セメント系固化材を、昇温速度が１０℃／分で、８００℃になるまで昇温した場合における２００～８００℃の重量減少率が１．０～５．０％であるものであり、かつ、上記土質改良材が、粉体又はスラリーであることを特徴とする土質改良材。
［２］ 上記土質改良材の固形分１００質量％中、上記セメント系固化材の割合が、７０～９９質量％で、かつ、上記硬化促進剤の割合が１～３０質量％である前記［１］に記載の土質改良材。
［３］ 上記セメント系固化材が、セメント、及び石膏を含み、かつ、高炉スラグ微粉末を含まないもの、又は、セメント、石膏、及び高炉スラグ微粉末を含むものであり、上記セメント系固化材中、上記セメントの割合が２０～９０質量％、上記石膏の割合が無水物換算で５～３０質量％、上記高炉スラグ微粉末の割合が０～６０質量％である前記［１］又は［２］に記載の土質改良材。
As a result of intensive studies to solve the above problems, the inventors of the present invention found that the weight loss rate from 200 to 800 degrees Celsius is 1.0 to 800 degrees Celsius when the temperature is raised to 800 degrees Celsius at a heating rate of 10 degrees C/min. The present invention has been completed based on the discovery that the above object can be achieved using a soil conditioner that contains a cement-based solidifying material of 5.0% and a hardening accelerator and is a powder or slurry.
That is, the present invention provides the following [1] to [6].
[1] A soil improvement material containing a cementitious solidifying agent and a hardening accelerator, wherein the cementitious solidifying agent heats the cementitious solidifying material at a temperature increase rate of 10°C/min until the temperature reaches 800°C. A soil improvement material having a weight loss rate of 1.0 to 5.0% at 200 to 800°C when heated, and wherein the soil improvement material is a powder or a slurry.
[2] The above-mentioned [1], wherein the proportion of the cement-based solidifying agent is 70 to 99% by mass and the proportion of the hardening accelerator is 1 to 30% by mass in 100% by mass of the solid content of the soil conditioner. ] The soil improvement material described in .
[3] The above-mentioned cement-based solidifying material contains cement and gypsum but does not contain pulverized blast furnace slag, or contains cement, gypsum, and pulverized blast-furnace slag, and the above-mentioned cement-based solidifying material [1] or [2] above, wherein the proportion of the cement is 20 to 90% by mass, the proportion of the gypsum is 5 to 30% by mass in terms of anhydride, and the proportion of the pulverized blast furnace slag is 0 to 60% by mass. ] The soil improvement material described in .
［４］ 上記硬化促進剤が、硫酸塩系、塩化物系、亜硝酸塩系、アルミナ系、チオシアン酸塩系、チオ硫酸塩系、及び炭酸塩系の中から選ばれる１種以上の硬化促進剤である前記［１］～［３］のいずれかに記載の土質改良材。
［５］ 前記［１］～［４］のいずれかに記載の土質改良材を用いた固化処理方法であって、未改良土に対して、上記土質改良材を添加し、混合して固化改良土を得る固化処理方法。
［６］ 上記未改良土１ｍ３に対する上記土質改良材の供給量が、固形分で、５０ｋｇ以上である前記［５］に記載の固化処理方法。
[4] The curing accelerator is one or more curing accelerators selected from sulfate-based, chloride-based, nitrite-based, alumina-based, thiocyanate-based, thiosulfate-based, and carbonate-based curing accelerators. The soil improvement material according to any one of [1] to [3] above.
[5] A solidification treatment method using the soil improving material according to any one of [1] to [4] above, in which the soil improving material is added to unimproved soil, mixed, and solidified. Solidification treatment method for obtaining soil.
[6] The solidification treatment method according to [5] above, wherein the amount of the soil improving material supplied per 1 m 3 of the unimproved soil is 50 kg or more in terms of solid content.
本発明の土質改良材及び固化処理方法は、材料として含まれるセメント系固化材が風化している場合であっても、強度発現性に優れたものである。 The soil improvement material and solidification treatment method of the present invention exhibit excellent strength development even when the cementitious solidification material included as the material is weathered.
本発明の土質改良材は、セメント系固化材と硬化促進剤を含む土質改良材であって、セメント系固化材が、該セメント系固化材を、昇温速度が１０℃／分で、８００℃になるまで昇温した場合における２００～８００℃の重量減少率が１．０～５．０％であるものであり、かつ、土質改良材が、粉体又はスラリーであるものである。
以下、詳しく説明する。
本明細書中、セメント系固化材とは、セメントを含み、かつ、任意に配合可能な混和材を含む、粉体状のものをいう。
セメント系固化材に用いられるセメントの例としては、普通ポルトランドセメント、早強ポルトランドセメント、中庸熱ポルトランドセメント、低熱ポルトランドセメント、耐硫酸塩ポルトランドセメント等の各種ポルトランドセメントや、高炉セメント、フライアッシュセメント、シリカセメント等の混合セメントや、エコセメントや、白色セメントや、超速硬セメント等が挙げられる。
中でも、強度発現性等の観点から、普通ポルトランドセメント、早強ポルトランドセメントが好ましい。
The soil conditioner of the present invention is a soil conditioner containing a cementitious solidifying agent and a hardening accelerator, wherein the cementitious solidifying agent is heated to 800°C at a heating rate of 10°C/min. The weight loss rate at 200 to 800°C is 1.0 to 5.0% when the temperature is raised to 1.0 to 5.0%, and the soil conditioner is a powder or slurry.
This will be explained in detail below.
In this specification, the cementitious solidifying material refers to a powdery material containing cement and optionally mixable admixtures.
Examples of cements used as cement-based solidifying agents include various Portland cements such as ordinary Portland cement, early strength Portland cement, moderate heat Portland cement, low heat Portland cement, and sulfate-resistant Portland cement, blast furnace cement, fly ash cement, Examples include mixed cement such as silica cement, ecocement, white cement, and super fast-hardening cement.
Among these, ordinary Portland cement and early strength Portland cement are preferred from the viewpoint of strength development and the like.
セメント系固化材中のセメントの割合は、好ましくは２０～９０質量％、より好ましくは２３～８５質量％、さらに好ましくは２５～７０質量％、さらに好ましくは２５～６０質量％、特に好ましくは２５～３５質量％である。上記割合が２０質量％以上であれば、固化改良土の強度（例えば、一軸圧縮強さ）をより大きくすることができる。また、上記割合が９０質量％以下であれば、材料にかかるコストをより低減し、廃棄物由来の原料の使用量をより多くすることができる。 The proportion of cement in the cementitious solidifying material is preferably 20 to 90% by mass, more preferably 23 to 85% by mass, even more preferably 25 to 70% by mass, even more preferably 25 to 60% by mass, particularly preferably 25% by mass. ~35% by mass. If the above ratio is 20% by mass or more, the strength (for example, unconfined compressive strength) of the consolidated improved soil can be further increased. Further, if the above ratio is 90% by mass or less, the cost of materials can be further reduced and the amount of raw materials derived from waste can be increased.
また、作業性がより向上する観点から、セメント系固化材としては、混和材として石膏を含むものが好ましい。セメント系固化材中の石膏の割合は、無水物換算で、好ましくは５～３０質量％、より好ましくは８～２８質量％、特に好ましくは１０～２５質量％である。
なお、上記石膏の割合には、セメントに含まれている石膏は含まれないものとする。
上記石膏の例としては、無水石膏、半水石膏、二水石膏、又はこれらの混合物等が挙げられる。
Further, from the viewpoint of further improving workability, the cement-based solidifying material preferably contains gypsum as an admixture. The proportion of gypsum in the cementitious solidifying material is preferably 5 to 30% by mass, more preferably 8 to 28% by mass, particularly preferably 10 to 25% by mass in terms of anhydride.
Note that the above ratio of gypsum does not include gypsum contained in cement.
Examples of the above-mentioned gypsum include anhydrite, hemihydrate gypsum, dihydrate gypsum, and mixtures thereof.
セメント系固化材は、固化改良土の強度（例えば、一軸圧縮強さ）をより大きくする観点や、材料にかかるコストを低減し、高炉スラグ微粉末の利用を促進する等の観点から、混和材として、高炉スラグ微粉末を含んでいてもよい。セメント系固化材中の高炉スラグ微粉末の割合は、好ましくは６０質量％以下、より好ましくは１０～５８質量％、さらに好ましくは２０～５５質量％、特に好ましくは３０～５０質量％である。上記割合が６０質量％以下であれば、相対的にセメントの量が多くなるため、固化改良土の強度（例えば、一軸圧縮強さ）をより大きくすることができる。
なお、セメント系固化材に含まれるセメントが高炉セメントである場合、高炉セメントに含まれる高炉スラグ微粉末は、上記割合に含まれるものとする。
石膏及び高炉スラグ微粉末以外の混和材の例としては、生石灰、消石灰、フライアッシュ、石灰石微粉末、及びシリカフューム等が挙げられる。これらは１種を単独で用いてもよく、２種以上を組み合わせて用いてもよい。
セメント系固化材中の石膏及び高炉スラグ微粉末以外の混和材（二種以上の混和材を含むものは、その合計）の割合は、相対的にセメントの割合が多くなり、固化改良土の強度をより大きくすることができる等の観点から、好ましくは２０質量％以下、より好ましくは１０質量％以下、特に好ましくは５質量％以下である。
Cement-based solidification agents are used as admixtures from the viewpoint of increasing the strength of solidified improved soil (for example, uniaxial compressive strength), reducing the cost of materials, and promoting the use of pulverized blast furnace slag powder. It may also contain pulverized blast furnace slag powder. The proportion of ground blast furnace slag powder in the cement solidifying material is preferably 60% by mass or less, more preferably 10 to 58% by mass, even more preferably 20 to 55% by mass, particularly preferably 30 to 50% by mass. When the above ratio is 60% by mass or less, the amount of cement becomes relatively large, so that the strength (for example, unconfined compressive strength) of the solidified improved soil can be further increased.
In addition, when the cement contained in the cement-based solidifying material is blast furnace cement, the blast furnace slag powder contained in the blast furnace cement shall be included in the above ratio.
Examples of admixtures other than gypsum and pulverized blast furnace slag include quicklime, slaked lime, fly ash, pulverized limestone, and silica fume. These may be used alone or in combination of two or more.
The proportion of admixtures other than gypsum and pulverized blast furnace slag in the cement-based solidifying material (the total of two or more types of admixtures) is relatively high, and the strength of the solidified improved soil increases. From the viewpoint of being able to increase the amount, the content is preferably 20% by mass or less, more preferably 10% by mass or less, particularly preferably 5% by mass or less.
セメント系固化材は、セメント系固化材を昇温速度が１０℃／分で、８００℃になるまで昇温した場合における２００～８００℃の重量減少率が１．０～５．０％、好ましくは１．２～４．６％、より好ましくは１．５～３．０％、さらに好ましくは１．６～２．５％であるものである。上記重量減少率が１．０％未満であると、土質改良材が硬化促進剤を含むことによる強度発現性の向上効果が小さくなる。また、重量減少率が１．０％未満であるセメント系固化材は、風化の程度が小さいため、風化によるセメント系固化材の強度発現性の低下も小さく、本発明の効果を得る必要性が少ない。上記重量減少率が５．０％を超える場合、土質改良材の強度発現性が低下する。
なお、２００～８００℃の重量減少率が大きい程、セメント系固化材中に、セメント系固化材の水和反応に寄与しない炭酸化カルシウム及び水酸化カルシウム（セメント系固化材の風化に伴って形成される化合物）が多く含まれていることを意味する。
上記重量減少率（質量減少率）は、以下の式（１）を用いて算出することができる。
重量減少率＝｛（２００℃におけるセメント系固化材の重量－８００℃におけるセメント系固化材の重量）／２００℃におけるセメント系固化材の重量｝×１００％・・・（１）
また、重量減少率は、市販の熱重量示差熱分析装置を用いて測定することができる。
The cement-based solidifying material preferably has a weight loss rate of 1.0-5.0% at 200-800°C when the cement-based solidifying material is heated to 800°C at a heating rate of 10°C/min. is 1.2 to 4.6%, more preferably 1.5 to 3.0%, even more preferably 1.6 to 2.5%. If the weight reduction rate is less than 1.0%, the effect of improving strength development by the soil conditioner containing a hardening accelerator becomes small. In addition, since the degree of weathering of a cement-based solidified material with a weight reduction rate of less than 1.0% is small, the decrease in strength development of the cement-based solidified material due to weathering is also small, and there is no need to obtain the effects of the present invention. few. When the weight reduction rate exceeds 5.0%, the strength development of the soil conditioner decreases.
Note that the larger the weight loss rate between 200 and 800°C, the more calcium carbonate and calcium hydroxide (formed as the cement solidifying material weathers) that do not contribute to the hydration reaction of the cement solidifying material. This means that it contains a large amount of chemical compounds.
The weight reduction rate (mass reduction rate) can be calculated using the following formula (1).
Weight reduction rate = {(Weight of cementitious solidifying material at 200°C - Weight of cementitious solidifying material at 800°C)/Weight of cementitious solidifying material at 200°C} x 100%... (1)
Moreover, the weight loss rate can be measured using a commercially available thermogravimetric differential thermal analyzer.
本明細書中、「硬化促進剤」とは、「ＪＩＳ Ａ ６２０４：２０１１（コンクリート用化学混和剤）」に規定されているものをいう。より具体的には、セメントの水和を早め、初期材齢の強度を大きくするための化学混和剤であって、上記硬化促進剤を用いていない場合の圧縮強度を１００％としたときに、材齢１日で１２０％以上、材齢２日で１３０％以上、材齢２８日で９０％以上の各値を満たすものをいう。ここで、「圧縮強度」とは、「ＪＩＳ Ａ １１０８：２０１８（コンクリートの圧縮強度試験方法）」に規定する方法で測定された値をいう。
硬化促進剤の例としては、硫酸塩系、塩化物系、亜硝酸塩系、アルミナ系、チオシアン酸塩系、チオ硫酸塩系、及び炭酸塩系等の硬化促進剤が挙げられる。これらは１種を単独で用いてもよく、２種以上を組み合わせて用いてもよい。
In this specification, the term "curing accelerator" refers to one defined in "JIS A 6204:2011 (Chemical admixtures for concrete)." More specifically, it is a chemical admixture for accelerating the hydration of cement and increasing the strength at the initial age, and when the compressive strength when the above-mentioned hardening accelerator is not used is 100%, This refers to materials that satisfy the following values: 120% or more at 1-day age, 130% or more at 2-day age, and 90% or more at 28-day age. Here, "compressive strength" refers to a value measured by the method specified in "JIS A 1108:2018 (concrete compressive strength testing method)".
Examples of the curing accelerator include sulfate-based, chloride-based, nitrite-based, alumina-based, thiocyanate-based, thiosulfate-based, and carbonate-based curing accelerators. These may be used alone or in combination of two or more.
硫酸塩系硬化促進剤の例としては、硫酸第一鉄、硫酸アルミニウム等が挙げられる。
塩化物系硬化促進剤の例としては、塩化カルシウム、塩化ナトリウム等が挙げられる。
亜硝酸塩系硬化促進剤の例としては、亜硝酸カルシウム、亜硝酸ナトリウム等が挙げられる。
アルミナ系硬化促進剤の例としては、カルシウムアルミネート、カルシウムアルミノフェライト、カルシウムハロアルミネート、カルシウムナトリウムアルミネート、カルシウムリチウムアルミネート、カルシウムサルフォアルミネート及びこれらの水和物等が挙げられる。
中でも、固化改良土の強度をより大きくすることができる観点から、塩化カルシウムが好ましい。
なお、硬化促進剤は、通常、粉体である。
Examples of sulfate-based hardening accelerators include ferrous sulfate, aluminum sulfate, and the like.
Examples of chloride-based hardening accelerators include calcium chloride, sodium chloride, and the like.
Examples of nitrite-based hardening accelerators include calcium nitrite, sodium nitrite, and the like.
Examples of the alumina hardening accelerator include calcium aluminate, calcium aluminoferrite, calcium haloaluminate, calcium sodium aluminate, calcium lithium aluminate, calcium sulfoaluminate, and hydrates thereof.
Among these, calcium chloride is preferred from the viewpoint of being able to further increase the strength of the solidified improved soil.
Note that the curing accelerator is usually a powder.
土質改良材の固形分１００質量％中、セメント系固化材の割合（土質改良材が水を含まない場合における、セメント系固化材の割合）は、好ましくは７０～９９質量％、より好ましくは７５～９７質量％、さらに好ましくは８２～９４質量％、特に好ましくは８６～９２質量％である。上記割合が７０質量％以上であれば、固化改良土の強度をより大きくすることができる。上記割合が９９質量％以下であれば、相対的に硬化促進剤の割合が大きくなるため、未改良土の含水比が大きい場合や、上述したセメント系固化材の重量減少率が大きい場合であっても、固化改良土の強度をより大きくすることができる。
土質改良材の固形分１００質量％中、硬化促進剤の割合（土質改良材が水を含まない場合における、硬化促進剤の割合）は、好ましくは１～３０質量％、より好ましくは３～２５質量％、さらに好ましくは６～１８質量％、特に好ましくは８～１４質量％である。上記割合が１質量％以上であれば、未改良土の含水比が大きい場合や、上述したセメント系固化材の重量減少率が大きい場合であっても、固化改良土の強度をより大きくすることができる。上記割合が３０質量％以下であれば、相対的にセメント系固化材の割合が大きくなるため、固化改良土の強度をより大きくすることができる。
The proportion of the cement solidifying agent in 100% by mass of the solid content of the soil conditioner (the proportion of the cementitious solidifying agent when the soil conditioner does not contain water) is preferably 70 to 99% by mass, more preferably 75% by mass. ~97% by weight, more preferably 82-94% by weight, particularly preferably 86-92% by weight. If the above ratio is 70% by mass or more, the strength of the solidified improved soil can be further increased. If the above ratio is 99% by mass or less, the ratio of the hardening accelerator will be relatively large, so it will not work when the moisture content of unimproved soil is high or when the weight loss rate of the above-mentioned cement-based solidification agent is high. However, the strength of compacted improved soil can be further increased.
The proportion of the hardening accelerator in 100% by mass of the solid content of the soil conditioner (the proportion of the hardening accelerator when the soil conditioner does not contain water) is preferably 1 to 30% by mass, more preferably 3 to 25% by mass. % by weight, more preferably 6-18% by weight, particularly preferably 8-14% by weight. If the above ratio is 1% by mass or more, the strength of the solidified improved soil can be increased even if the water content of the unimproved soil is high or the weight loss rate of the cement solidified material is large. I can do it. If the above ratio is 30% by mass or less, the ratio of the cement-based solidifying agent becomes relatively large, so that the strength of the solidified improved soil can be further increased.
本発明の土質改良材によれば、軟弱地盤等の強度（例えば、一軸圧縮強さ）の小さい未改良土を、強度のより大きな土（固化改良土）にすることができる。
土質改良材を用いた未改良土の固化処理方法の一例としては、未改良土に対して、土質改良材を添加し、混合して固化改良土を得る方法が挙げられる。
固化処理の対象となる未改良土は、特に限定されるものではないが、含水比が、１００％以上（より好ましくは１５０～１，０００％、さらに好ましくは３００～８００％、特に好ましくは４００～７００％）である未改良土が好ましい。
一般的に、未改良土の含水比が１００％以上である場合、土質改良材の強度発現性が小さくなるが、本発明の土質改良材によれば、含水比が１００％以上であるような未改良土であっても、固化改良土の強度を大きくすることができる。
なお、「含水比」（単位：％）とは、未改良土に含まれる固体の質量に対する、未改良土に含まれる水の質量の百分率（（水／固体）×１００％）をいう。
According to the soil improving material of the present invention, unimproved soil with low strength (for example, unconfined compressive strength) such as soft ground can be made into soil with higher strength (improved solidified soil).
An example of a method for solidifying unimproved soil using a soil improving material is a method in which a soil improving material is added to unimproved soil and mixed to obtain solidified improved soil.
The unimproved soil to be subjected to solidification treatment is not particularly limited; -700%) is preferred.
Generally, when the water content ratio of unimproved soil is 100% or more, the strength development of the soil conditioner is reduced, but according to the soil conditioner of the present invention, when the water content ratio is 100% or more, Even if it is unimproved soil, the strength of solidified improved soil can be increased.
Note that "water content ratio" (unit: %) refers to the percentage of the mass of water contained in unimproved soil to the mass of solid contained in unimproved soil ((water/solid) x 100%).
土質改良材は、粉体の状態で添加し、混合してもよく（ドライ添加方法）、スラリーの状態で添加し、混合してもよい（スラリー添加方法）。
例えば、未改良土の含水比が小さい場合（例えば、含水比が３００％未満である場合）、未改良土からなる層の厚みが大きく、中層混合処理工法や、深層混合処理工法を用いて固化処理を行う場合、未改良土に土質改良材をより均一に混合したい場合等には、固化改良土の強度をより大きくする観点から、スラリーの状態の土質改良材を、未改良土に供給することが好ましい。この場合、セメント系固化材と硬化促進剤と水を予め混合し、スラリーの形態とした後、該スラリーを未改良土に供給する。
また、粉体状の土質改良材と水を別々に未改良土に供給してもよい。なお、粉体状の土質改良材は、通常、水を除く粉状の各材料を混合することで得ることができる。
土質改良材をスラリーの状態で用いる場合、水粉体比（水と粉体（セメント系固化材と硬化促進剤の混合物）の質量比（水／粉体）を百分率で表したもの）は、土質改良材の強度発現性や、未改良土との混合の容易性等の観点から、好ましくは５０～２００％、より好ましくは６０～１５０％、特に好ましくは７０～１２０％である。
The soil conditioner may be added in the form of a powder and mixed (dry addition method), or may be added in the form of a slurry and mixed (slurry addition method).
For example, if the moisture content of unimproved soil is low (for example, if the moisture content is less than 300%), the thickness of the layer of unimproved soil is large, and solidification can be achieved using the mid-layer mixing method or the deep-layer mixing method. When performing treatment, if you want to mix the soil conditioner more uniformly into the unimproved soil, feed the soil conditioner in the form of a slurry to the unimproved soil in order to increase the strength of the solidified improved soil. It is preferable. In this case, a cement-based solidifying agent, a hardening accelerator, and water are mixed in advance to form a slurry, and then the slurry is supplied to unimproved soil.
Further, the powdered soil conditioner and water may be separately supplied to unimproved soil. Note that the powdered soil conditioner can usually be obtained by mixing powdered materials excluding water.
When using the soil conditioner in the form of a slurry, the water-powder ratio (the mass ratio (water/powder) of water and powder (mixture of cementitious solidifying agent and hardening accelerator) expressed as a percentage) is as follows: From the viewpoint of strength development of the soil conditioner and ease of mixing with unimproved soil, it is preferably 50 to 200%, more preferably 60 to 150%, particularly preferably 70 to 120%.
未改良土１ｍ３に対する土質改良材の供給量は、対象となる未改良土の性状、施工条件、並びに、処理後に得られる固化改良土に求められる強度等によっても異なるが、未改良土１ｍ３に対して、固形分で、好ましくは５０ｋｇ以上、より好ましくは８０～６００ｋｇ、より好ましくは１００～５００ｋｇ、特に好ましくは１５０～４５０ｋｇである。
上記供給量が５０ｋｇ以上であれば、固化改良土の強度をより大きくすることができる。上記供給量が６００ｋｇ以下であれば、コストの過度な増加を防ぐことができる。
The amount of soil improvement material supplied per 1 m 3 of unimproved soil varies depending on the properties of the target unimproved soil, construction conditions, and the strength required of the solidified improved soil obtained after treatment. In contrast, the solid content is preferably 50 kg or more, more preferably 80 to 600 kg, more preferably 100 to 500 kg, particularly preferably 150 to 450 kg.
If the above-mentioned supply amount is 50 kg or more, the strength of the solidified improved soil can be further increased. If the above-mentioned supply amount is 600 kg or less, an excessive increase in cost can be prevented.
また、セメント系固化材の、セメント系固化材を昇温速度が１０℃／分で、８００℃になるまで昇温した場合における２００～８００℃の重量減少率を測定し、得られた重量減少率に基いて、土質改良材を調製してもよい。
具体的には、セメント系固化材の上記重量減少率が１．０％未満である場合、セメント系固化材をそのまま土質改良材とし、セメント系固化材の上記重量減少率が１．０～５．０％である場合、セメント系固化材と硬化促進剤を混合して、土質改良材を得る方法等が挙げられる。
また、セメント系固化材に含まれるセメント以外の材料（石膏、高炉スラグ微粉末等）の割合を適宜変更して、セメント系固化材の上記重量減少率が所望の数値（例えば、１．０～５．０％）となるように、適宜調整してもよい。
In addition, the weight loss rate of the cement-based solidifying material from 200 to 800°C was measured when the temperature of the cement-based solidifying material was raised to 800°C at a heating rate of 10°C/min. A soil conditioner may be prepared based on the ratio.
Specifically, when the weight reduction rate of the cementitious solidification material is less than 1.0%, the cementitious solidification material is used as a soil conditioner, and the weight reduction rate of the cementitious solidification material is 1.0 to 5%. When the content is 0%, a method may be used in which a cement-based solidifying agent and a hardening accelerator are mixed to obtain a soil conditioner.
In addition, by appropriately changing the proportion of materials other than cement (gypsum, pulverized blast furnace slag, etc.) contained in the cementitious solidifying material, the weight reduction rate of the cementitious solidifying material can be adjusted to a desired value (for example, 1.0 to 5.0%).
以下、本発明を実施例により具体的に説明するが、本発明はこれらの実施例に限定されるものではない。
［使用材料］
（１）セメント１；普通ポルトランドセメント、密度：３．１２ｇ／ｃｍ３、ブレーン比表面積：３，８００ｃｍ２／ｇ、室温～１，０００℃の重量減少率：５．２％
（２）セメント２；普通ポルトランドセメント、密度：３．１６ｇ／ｃｍ３、ブレーン比表面積：３，３００ｃｍ２／ｇ、室温～１，０００℃の重量減少率：２．９％
（３）高炉スラグ微粉末（表２～３中、「高炉スラグ」と示す。）；デイ・シイ社製、商品名「セラメント」、密度：２．９０ｇ／ｃｍ３、ブレーン比表面積：４，８００ｃｍ２／ｇ、室温～１，０００℃の重量減少率：０．４％
（４）石膏１；無水石膏（表２～３中、「無水」と示す。）、密度：２．７０ｇ／ｃｍ３、ブレーン比表面積：４，１００ｃｍ２／ｇ、室温～１，０００℃の重量減少率：０．２％
（５）石膏２；半水石膏（表２～３中、「半水」と示す。）、密度：２．６２ｇ／ｃｍ３、ブレーン比表面積：４，２００ｃｍ２／ｇ、室温～１，０００℃の重量減少率：６．４％
（６）石膏３；二水石膏（表２～３中、「二水」と示す。）、密度：２．３２ｇ／ｃｍ３、ブレーン比表面積：３，２００ｃｍ２／ｇ、室温～１，０００℃の重量減少率：２０．７％
（７）硬化促進剤Ａ；硫酸第一鉄
（８）硬化促進剤Ｂ；塩化カルシウム
（９）硬化促進剤Ｃ；カルシウムアルミネート系水和物
（１０）硬化促進剤Ｄ；亜硝酸カルシウム
（１１）有機質土１～２；詳細は表１に示す。
なお、材料（１）～（６）の室温～１，０００℃の重量減少率とは、熱重量示差熱分析（ＤＴＡ－ＴＧ）装置を用いて、窒素ガスの量が２００ｍｌ／分であり、１０℃／分の昇温速度の条件で、室温から１，０００℃になるまで昇温させた際の重量減少率（｛（室温における材料の重量－１，０００℃における材料の重量）／室温における材料の重量×１００％｝）である。
EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.
[Materials used]
(1) Cement 1: Ordinary Portland cement, density: 3.12 g/cm 3 , Blaine specific surface area: 3,800 cm 2 /g, weight loss rate from room temperature to 1,000°C: 5.2%
(2) Cement 2: Ordinary Portland cement, density: 3.16 g/cm 3 , Blaine specific surface area: 3,300 cm 2 /g, weight loss rate from room temperature to 1,000°C: 2.9%
(3) Pulverized blast furnace slag powder (indicated as "blast furnace slag" in Tables 2 and 3); manufactured by DC Corporation, trade name "Cerament", density: 2.90 g/cm 3 , Blaine specific surface area: 4, 800cm 2 /g, weight loss rate from room temperature to 1,000°C: 0.4%
(4) Gypsum 1: Anhydrous gypsum (indicated as "anhydrous" in Tables 2 and 3), density: 2.70 g/cm 3 , Blaine specific surface area: 4,100 cm 2 /g, room temperature to 1,000°C Weight reduction rate: 0.2%
(5) Gypsum 2; Hemihydrate gypsum (indicated as "Halfwater" in Tables 2 and 3), density: 2.62 g/cm 3 , Blaine specific surface area: 4,200 cm 2 /g, room temperature to 1,000 Weight loss rate in °C: 6.4%
(6) Gypsum 3; Gypsum dihydrate (indicated as "dihydrate" in Tables 2 and 3), density: 2.32 g/cm 3 , Blaine specific surface area: 3,200 cm 2 /g, room temperature to 1,000 Weight loss rate in °C: 20.7%
(7) Curing accelerator A; ferrous sulfate (8) Curing accelerator B; Calcium chloride (9) Curing accelerator C; Calcium aluminate hydrate (10) Curing accelerator D; Calcium nitrite (11 ) Organic soil 1-2; details are shown in Table 1.
In addition, the weight loss rate of materials (1) to (6) from room temperature to 1,000°C is measured using a thermogravimetric differential thermal analysis (DTA-TG) device at a nitrogen gas flow rate of 200 ml/min. Weight loss rate when heating from room temperature to 1,000°C under the condition of heating rate of 10°C/min ({(weight of material at room temperature - weight of material at 1,000°C)/room temperature weight of material x 100%}).
［実施例１～５］
材料として、表２に示す種類の普通ポルトランドセメント及び石膏、並びに高炉スラグ微粉末を含み、セメント系固化材中の各材料の割合が表２に示す割合である粉体状のセメント系固化材を得た。
セメント系固化材の、熱重量示差熱分析（ＴＧ－ＤＴＡ）装置を用いて、窒素ガスの装置内への量が２００ｍｌ／分であり、１０℃／分の昇温速度の条件で、室温から１，０００℃になるまで昇温させた場合の、２００～８００℃の重量減少率（｛（２００℃におけるセメント系固化材の重量－８００℃におけるセメント系固化材の重量）／２００℃におけるセメント系固化材の重量×１００％｝）を算出した。得られた値を表２に示す。
上記セメント系固化材と、表２に示す種類の硬化促進剤を、表２に示す質量比となる量で混合して粉体状の土質改良材を得た。
有機質土１に、有機質土１ｍ３当たりの土質改良材の添加量が４００ｋｇとなる粉体状の土質改良材を添加して混合し、固化改良土を得た。
得られた固化改良土の材齢２８日における一軸圧縮強さを、「ＪＩＳ Ａ １２１６：２０２０（土の一軸圧縮試験方法）」に準拠して測定した。
［比較例１～３、５］
硬化促進剤を使用せず、セメント系固化材を土質改良材とする以外は実施例１と同様にして、固化改良土を得た。実施例１と同様にして、一軸圧縮強さ等を測定した。
［比較例４］
実施例１と同様にして、固化改良土を得た。実施例１と同様にして、一軸圧縮強さ等を測定した。
[Examples 1 to 5]
As materials, a powdered cementitious solidifying material containing the types of ordinary Portland cement and gypsum shown in Table 2, and pulverized blast furnace slag, and the proportion of each material in the cementitious solidifying material is as shown in Table 2. Obtained.
Using a thermogravimetric differential thermal analysis (TG-DTA) device, a cementitious solidifying material was measured from room temperature under the conditions that the amount of nitrogen gas into the device was 200 ml/min and the temperature was increased at a rate of 10°C/min. Weight loss rate from 200 to 800°C when the temperature is raised to 1,000°C ({(Weight of cementitious solidifying agent at 200°C - Weight of cementitious solidifying agent at 800°C)/Cement at 200°C Weight of system solidifying material x 100%}) was calculated. The obtained values are shown in Table 2.
The above cementitious solidifying material and the hardening accelerator shown in Table 2 were mixed in amounts having mass ratios shown in Table 2 to obtain a powdery soil conditioner.
Powdered soil conditioner was added to organic soil 1 in an amount of 400 kg per 1 m 3 of organic soil to obtain solidified improved soil.
The unconfined compressive strength of the obtained consolidated improved soil at 28 days of age was measured in accordance with "JIS A 1216:2020 (Unconfined compression test method for soil)".
[Comparative Examples 1 to 3, 5]
Improved solidified soil was obtained in the same manner as in Example 1, except that no hardening accelerator was used and a cement-based solidifying agent was used as the soil conditioner. Uniaxial compressive strength etc. were measured in the same manner as in Example 1.
[Comparative example 4]
Solidified improved soil was obtained in the same manner as in Example 1. Uniaxial compressive strength etc. were measured in the same manner as in Example 1.
［実施例６］
セメント１、無水石膏、及び高炉スラグ微粉末を含み、セメント系固化材中の各材料の割合が表３に示す割合であるセメント系固化材を得た。
実施例１と同様にして、セメント系固化材の、２００～８００℃の重量減少率を算出した。
上記セメント系固化材と、表３に示す種類の硬化促進剤を、表３に示す質量比となる量で混合して粉体状の土質改良材を得た。
次いで、粉体状の土質改良材と、該土質改良材と同じ質量の水を混合して、水粉体比（水と粉体状の土質改良材の質量比を１００分率で表したもの）が１００％であるスラリーを得た。
有機質土２に、有機質土１ｍ３当たりの土質改良材（固形分）の添加量が１００ｋｇとなる量の上記スラリーを添加して混合し、固化改良土を得た。
得られた固化改良土の一軸圧縮強さを、実施例１と同様にして測定した。
［比較例６］
硬化促進剤を使用せず、セメント系固化材を土質改良材とする以外は実施例６と同様にして、固化改良土を得た。実施例６と同様にして、一軸圧縮強さ等を測定した。
［参考例１］
セメント１の代わりにセメント２を使用し、２００～８００℃の重量減少率が表３に示す値であるセメント系固化材を用いた以外は、実施例６と同様にして、固化改良土を得た。実施例６と同様にして、一軸圧縮強さ等を測定した。
［参考例２］
セメント１の代わりにセメント２を使用し、２００～８００℃の重量減少率が表３に示す値であるセメント系固化材を用いた以外は、比較例６と同様にして、固化改良土を得た。比較例６と同様にして、一軸圧縮強さ等を測定した。
結果を表３に示す。
[Example 6]
A cementitious solidifying material containing cement 1, anhydrite, and pulverized blast furnace slag powder was obtained, in which the proportions of each material in the cementitious solidifying material were as shown in Table 3.
In the same manner as in Example 1, the weight loss rate of the cement solidifying material at 200 to 800°C was calculated.
The above cementitious solidifying material and hardening accelerators of the type shown in Table 3 were mixed in amounts having mass ratios shown in Table 3 to obtain a powdery soil conditioner.
Next, a powdered soil conditioner and water of the same mass as the soil conditioner are mixed to obtain a water-powder ratio (the mass ratio of water and powdered soil conditioner expressed as a percentage). ) was obtained to be 100%.
The above slurry was added to organic soil 2 in an amount such that the amount of soil conditioner (solid content) added was 100 kg per 1 m 3 of organic soil and mixed to obtain solidified improved soil.
The uniaxial compressive strength of the obtained consolidated improved soil was measured in the same manner as in Example 1.
[Comparative example 6]
Improved solidified soil was obtained in the same manner as in Example 6, except that no hardening accelerator was used and a cement-based solidifying agent was used as the soil conditioner. Uniaxial compressive strength etc. were measured in the same manner as in Example 6.
[Reference example 1]
Solidified improved soil was obtained in the same manner as in Example 6, except that Cement 2 was used instead of Cement 1, and a cement-based solidifying material whose weight loss rate from 200 to 800°C was the value shown in Table 3. Ta. Uniaxial compressive strength etc. were measured in the same manner as in Example 6.
[Reference example 2]
Solidified improved soil was obtained in the same manner as Comparative Example 6, except that Cement 2 was used instead of Cement 1, and a cement-based solidifying material whose weight loss rate from 200 to 800°C was the value shown in Table 3. Ta. Uniaxial compressive strength etc. were measured in the same manner as Comparative Example 6.
The results are shown in Table 3.
表２～３から、実施例１と比較例１（硬化促進剤を用いない以外は実施例１と同様のもの）の比較から、本発明の土質改良材によれば、固化改良土の一軸圧縮強さをより大きくすることができることがわかる。同様の傾向は、実施例２と比較例３、実施例３と比較例２、実施例４と比較例１、実施例５と比較例５、実施例６と比較例６の各々の比較でも見られた。
また、表３の参考例１と参考例２を比較すると、セメント系固化材の重量減少率が０．８％である場合、セメント系固化材のみを用いた参考例２の材齢２８日の一軸圧縮強さは５５０ｋＮ／ｍ２であるのに対して、セメント系固化材及び硬化促進剤を使用した参考例１の固化改良土の材齢２８日の一軸圧縮強さは４４０ｋＮ／ｍ２であることがわかる。このことから、セメント系固化材の重量減少率が０．８％である場合（すなわち、セメント系固化材の風化が進んでいない場合）、硬化促進剤を用いても、固化改良土の一軸圧縮強さは大きくならないことがわかる。
From Tables 2 and 3, from the comparison of Example 1 and Comparative Example 1 (same as Example 1 except that no hardening accelerator was used), it was found that according to the soil conditioner of the present invention, uniaxial compression of the solidified improved soil It turns out that the strength can be increased. Similar trends were observed in the comparisons of Example 2 and Comparative Example 3, Example 3 and Comparative Example 2, Example 4 and Comparative Example 1, Example 5 and Comparative Example 5, and Example 6 and Comparative Example 6. It was done.
In addition, when comparing Reference Example 1 and Reference Example 2 in Table 3, when the weight reduction rate of the cement-based solidifying material is 0.8%, the material age of Reference Example 2 using only the cement-based solidifying material is 28 days. The unconfined compressive strength is 550 kN/ m2 , while the unconfined compressive strength of the consolidated improved soil of Reference Example 1 using a cement-based solidifying agent and hardening accelerator at 28 days of age is 440 kN/ m2. I understand that there is something. From this, it can be seen that if the weight reduction rate of the cement-based solidifying material is 0.8% (i.e., when the cement-based solidifying material has not been weathered), even if a hardening accelerator is used, the uniaxial compression of the solidified improved soil It turns out that the strength does not increase.
Claims (5)
上記セメント系固化材が、該セメント系固化材を、昇温速度が１０℃／分で、８００℃になるまで昇温した場合における２００～８００℃の重量減少率が１．０～５．０％であるものであり、かつ、
上記土質改良材が、粉体又はスラリーであり、
上記硬化促進剤が、硫酸塩系、塩化物系、亜硝酸塩系、及びアルミナ系の中から選ばれる１種以上の硬化促進剤であることを特徴とする土質改良材。 A soil conditioner containing a cement solidifying agent and a hardening accelerator,
The weight loss rate of the cementitious solidifying material at 200 to 800°C is 1.0 to 5.0 when the cementitious solidifying material is heated to 800°C at a heating rate of 10°C/min. %, and
The soil improvement material is a powder or slurry,
A soil improvement material characterized in that the hardening accelerator is one or more hardening accelerators selected from sulfate-based, chloride-based, nitrite-based, and alumina-based.
上記セメント系固化材中、上記セメントの割合が２０～９０質量％、上記石膏の割合が無水物換算で５～３０質量％、上記高炉スラグ微粉末の割合が０～６０質量％である請求項１又は２に記載の土質改良材。 The cementitious solidifying material contains cement and gypsum but does not contain pulverized blast furnace slag, or contains cement, gypsum, and pulverized blast furnace slag,
A claim in which, in the cementitious solidifying material, the proportion of the cement is 20 to 90% by mass, the proportion of the gypsum is 5 to 30% by mass in terms of anhydride, and the proportion of the ground blast furnace slag powder is 0 to 60% by mass. The soil improvement material described in 1 or 2.
未改良土に対して、上記土質改良材を添加し、混合して固化改良土を得る固化処理方法。 A solidification treatment method using the soil improvement material according to any one of claims 1 to 3 ,
A solidification treatment method in which the above-mentioned soil conditioner is added to unimproved soil and mixed to obtain solidified improved soil.
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