JP3526096B2 - Soft ground improvement material - Google Patents
Soft ground improvement materialInfo
- Publication number
- JP3526096B2 JP3526096B2 JP00887795A JP887795A JP3526096B2 JP 3526096 B2 JP3526096 B2 JP 3526096B2 JP 00887795 A JP00887795 A JP 00887795A JP 887795 A JP887795 A JP 887795A JP 3526096 B2 JP3526096 B2 JP 3526096B2
- Authority
- JP
- Japan
- Prior art keywords
- soft ground
- cement
- ground improvement
- improvement material
- hardened
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
Description
【発明の詳細な説明】
【０００１】
【産業上の利用分野】本発明は、硬化したセメントを熱
処理して再活性化させた軟弱地盤改良材に関する。
【０００２】
【従来の技術】従来、コンクリートは役割を終えると砕
かれてコンクリート塊となり、産業廃棄物として棄却さ
れてきた。近年投棄場所の確保が困難になってきたた
め、コンクリートの再生利用方法としてコンクリートを
砕いた後、ふるい分けを行って骨材を取り出し、骨材は
再びコンクリート用骨材として利用し、骨材を除いた後
の硬化したセメント、いわゆる硬化セメントは埋め戻し
用に利用する試みがなされている。しかしながら硬化セ
メントの利用方法が、埋め戻し用という程度ではコンク
リートの再生利用法として十分とは言えず、より有益な
硬化セメントの再生利用法の開発が強く望まれている。
【０００３】
【発明が解決しようとする課題】本発明は、上記したよ
うな従来の問題点を鑑みてなされたもので、その目的と
するところは、一度硬化した硬化セメントを再び活性化
させ、軟弱地盤改良材として有効利用することにある。
【０００４】
【課題を解決するための手段】本発明は、硬化したセメ
ントを４００℃乃至１３００℃の温度で、３乃至１２０
分間、熱処理してなる軟弱地盤改良材に関する。
【０００５】
【作用】セメントは主としてカルシウムシリケートと呼
ばれる酸化カルシウムと二酸化珪素の化合物からなり、
他に酸化カルシウムと酸化アルミニウムおよび酸化第２
鉄が組合わさった化合物も少量含む。セメントと水を混
ぜ合わせるとこれらの化合物と水が反応し、カルシウム
シリケートの場合はカルシウムシリケート水和物を、そ
の他の化合物もそれぞれの水和物を生成して硬化する。
カルシウムシリケートの場合は、水和反応過程で酸化カ
ルシウムと水だけの化合物である水酸化カルシウムも併
せて生成する。本発明は、硬化したセメントを４００℃
乃至１３００℃の温度で、好ましくは４００℃乃至８０
０℃の温度で熱処理すると、水和物として結合していた
水が脱水されて活性化し、得られた脱水物は軟弱地盤改
良材として極めて優れていることの知見に基づいてい
る。
【０００６】硬化したセメントを熱処理して脱水させる
と、カルシウムシリケート水和物や水酸化カルシウムか
ら水を除いた物質が残り、この活性化された脱水物はこ
れに再び水を加えると、ただちに水と反応して元の水和
物に戻り硬化する作用がある。
【０００７】本発明において熱処理温度が１３００℃を
越える高温になると、結合していた水が脱水された後化
合物の組替えが起こって元のセメントに戻る。当然のこ
とながら加熱温度が高くなるほどエネルギー消費量が多
くなるし、加熱設備も大がかりになるが、セメントその
ものは大規模工場設備で多量に製造されているので、高
いコストをかけて硬化セメントを元のセメントに戻すの
は、硬化セメントの再生利用方法として適当でない。ま
た熱処理温度が低すぎると、脱水が十分でなく軟弱地盤
改良材としての効果が不十分になる。熱処理時間は、硬
化したセメントの結合水が脱水できる時間であれば特に
制限されず、温度が高いほど短時間でよいが、普通には
３分乃至１２０分間、好ましくは５分乃至６０分間であ
る。また熱処理は空気などの酸素含有ガス雰囲気下で行
うのが好適である。
【０００８】本発明において、硬化したセメントとして
は、産業廃棄物として排出される使用済のコンクリー
ト、モルタル、未使用で放置されて硬化したセメントな
どを挙げることができ、コンクリートやモルタル塊は粗
粉砕して粗骨材、細骨材などを分離あるいは分離せずに
使用しても差し支えない。また硬化したセメントは、特
にその種類に制限はなく、セメント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、超早強ポルトラ
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、ビーライト系ポルトランドセメン
ト、高炉セメント、フライアッシュセメント、多成分混
合セメントなどいずれであってもよい。
【０００９】
【実施例】以下実施例により、本発明を具体的に説明す
る。
実施例１〜３、比較例１
表１に示す性状の有機質粘性土に、硬化した普通ポルト
ランドセメントを表２に示す製造条件で空気雰囲気下に
加熱して製造した軟弱地盤改良材を１０重量％（以下％
は重量％を意味する）添加し、材令２８日の一軸圧縮強
度を測定した。軟弱地盤改良材は、硬化した普通ポルト
ランドセメントを表２に示す製造条件で空気雰囲気下に
加熱して製造した。軟弱地盤改良材による固化試験結果
を同じく表２に示す。
【００１０】
【表１】
【００１１】
【表２】
【００１２】実施例４〜６、比較例２
表３に示す性状の有機質土混じり砂質土に、実施例１〜
３と同様に硬化した普通ポルトランドセメントを表４に
示す製造条件で空気雰囲気下に加熱して製造した軟弱地
盤改良材を１０％添加し、材令２８日の一軸圧縮強度を
測定した。軟弱地盤改良材による固化試験結果を同じく
表４に示す。
【００１３】
【表３】【００１４】
【表４】
【００１５】上記試験結果より、本発明の軟弱地盤改良
材混入後の軟弱地盤の一軸圧縮強度は、０．５ｋｇｆ／
ｃｍ2 以上であり、軟弱地盤改良材として十分な性能を
有している。
【００１６】
【発明の効果】本発明による軟弱地盤改良材は元のセメ
ントに比べて大きく性状が異なり、建造物の築造のよう
な通常のセメントの用い方はできないが、軟弱地盤に添
加すれば地盤を固化する性能を発揮するので、軟弱地盤
改良材としては十分に利用することができる。また、本
発明の軟弱地盤改良材は、ネバリケの強い粘性土があた
かも砂に変わったようにサラサラした土に変化する現象
いわゆる団粒化作用を示すので土との混合作業が容易で
ある。さらに、他の軟弱地盤改良材である生石灰のよう
に多量の発熱をすることがないので、取扱いに危険がな
く、混合作業において作業環境を悪化させることがな
い。その上、コンクリートは硬化セメントと骨材の混合
物なので、使用済コンクリートをそのまま加熱すると骨
材の混じったものになるが、骨材が混入しても軟弱地盤
改良材として使用するのになんら支障はないので、使用
済コンクリートからも本発明による軟弱地盤改良材を容
易に得ることができる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft ground improvement material in which hardened cement is reactivated by heat treatment. 2. Description of the Related Art Conventionally, concrete has been crushed when it has finished its role, and has been discarded as industrial waste. In recent years, it has become difficult to secure a dumping site, so concrete is crushed as a method of recycling concrete, sieved, aggregate is taken out, aggregate is reused as concrete aggregate, and aggregate is removed. Attempts have been made to use later hardened cement, so-called hardened cement, for backfilling. However, the method of using hardened cement is not sufficient as a method of recycling concrete because it is used for backfilling, and the development of a more useful method of recycling hardened cement is strongly desired. [0003] The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to re-activate a hardened cement which has been hardened once. Effective use as a soft ground improvement material. [0004] The present invention SUMMARY OF] is a cured temperature of cement 400 ° C. to 1300 ° C., 3 to 120
Minute heat treatment for soft ground. [0005] The cement is mainly composed of a compound of calcium oxide and silicon dioxide called calcium silicate,
In addition, calcium oxide and aluminum oxide and secondary oxide
It also contains small amounts of compounds with iron. When cement and water are mixed, these compounds and water react, and in the case of calcium silicate, calcium silicate hydrate is formed, and other compounds also form their respective hydrates and harden.
In the case of calcium silicate, calcium hydroxide, which is a compound consisting only of calcium oxide and water, is also formed during the hydration reaction. The present invention relates to a method in which
At a temperature of from 1 to 1300 ° C, preferably from 400 to 80 ° C.
It is based on the finding that when heat-treated at a temperature of 0 ° C., water bound as a hydrate is dehydrated and activated, and the obtained dehydrated product is extremely excellent as a soft ground improvement material. When the hardened cement is dehydrated by heat treatment, calcium silicate hydrate and a substance obtained by removing water from calcium hydroxide remain, and the activated dehydrated water is added to water immediately after the addition of water. Has the effect of returning to the original hydrate and hardening. In the present invention, when the heat treatment temperature is higher than 1300 ° C., the bound water is dehydrated and the compounds are rearranged to return to the original cement. Naturally, the higher the heating temperature, the higher the energy consumption and the larger the heating equipment, but since the cement itself is manufactured in large quantities in large-scale factory equipment, the cost is high and the hardened cement is expensive. Is not suitable as a method for recycling hardened cement. On the other hand, if the heat treatment temperature is too low, dehydration is not sufficient, and the effect as a soft ground improving material becomes insufficient. The heat treatment time is not particularly limited as long as the bound water of the hardened cement can be dehydrated. The higher the temperature, the shorter the time. However, it is usually 3 minutes to 120 minutes, preferably 5 minutes to 60 minutes. . The heat treatment is preferably performed in an oxygen-containing gas atmosphere such as air. In the present invention, examples of the hardened cement include used concrete and mortar discharged as industrial waste, and cement hardened by leaving unused, and concrete and mortar blocks are roughly pulverized. The coarse aggregate and the fine aggregate may be separated or used without being separated. The type of hardened cement is not particularly limited, and the cement is usually Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, medium-heat Portland cement, low-heat Portland cement, belite Portland cement, blast furnace cement, and fly. Any of ash cement and multi-component mixed cement may be used. The present invention will be described in detail with reference to the following examples. Examples 1 to 3 and Comparative Example 1 10% by weight of a soft ground improving material produced by heating hardened ordinary Portland cement in an air atmosphere under the production conditions shown in Table 2 on an organic clay soil having the properties shown in Table 1 (Less than%
Means weight%), and the unconfined compressive strength of 28 days old was measured. The soft ground improving material was manufactured by heating hardened ordinary Portland cement under the manufacturing conditions shown in Table 2 under an air atmosphere. Table 2 also shows the results of the solidification test using the soft ground improvement material. [Table 1] [Table 2] Examples 4 to 6 and Comparative Example 2 Examples 1 to 6 were applied to sandy soil mixed with organic soil having the properties shown in Table 3.
In the same manner as in Example 3, the hardened ordinary Portland cement was heated under an air atmosphere under the manufacturing conditions shown in Table 4, and 10% of a soft ground improvement material manufactured was added. Table 4 also shows the results of the solidification test using the soft ground improvement material. [Table 3] [Table 4] From the above test results, the unconfined compressive strength of the soft ground after mixing with the soft ground improving material of the present invention is 0.5 kgf /
cm 2 or more, and has sufficient performance as a soft ground improvement material. The soft ground improvement material according to the present invention has properties greatly different from those of the original cement, and cannot be used with ordinary cement such as construction of buildings, but if added to soft ground, Since it exhibits the performance of solidifying the ground, it can be sufficiently used as a soft ground improvement material. In addition, the soft ground improvement material of the present invention exhibits a phenomenon in which a strong cohesive soil with a high level of nebari turns into a smooth soil as if it were changed to sand, that is, a so-called agglomeration action, so that the mixing operation with the soil is easy. Furthermore, since it does not generate a large amount of heat unlike quick lime which is another soft ground improvement material, there is no danger in handling and the working environment is not deteriorated in the mixing operation. In addition, concrete is a mixture of hardened cement and aggregate, so if the used concrete is heated as it is, it will be a mixture of aggregate.However, even if the aggregate is mixed, there is no problem in using it as a soft ground improvement material. Therefore, the soft ground improvement material according to the present invention can be easily obtained from used concrete.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平６−285454（ＪＰ，Ａ) 特開 平６−322745（ＪＰ，Ａ) 特開 平６−322761（ＪＰ，Ａ) 特開 平６−313314（ＪＰ，Ａ) 小嶋他２名，コンクリート廃材から再 生セメントの試製，第85回学術講演会講 演要旨，石膏石灰学会，1992年10月８ 日，ｐ22−23 ────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-6-285454 (JP, A) JP-A-6-322745 (JP, A) JP-A-6-322761 (JP, A) JP-A-6-313314 (JP, A) Kojima and two others re-use concrete waste Trial production of raw cement, 85th academic lecture Abstract, Gypsum and Lime Society, October 8, 1992 Sun, p22-23
Claims (1)
℃の温度で、３乃至１２０分間、熱処理してなる軟弱地
盤改良材。(57) [Claim 1] The cured cement is heated at 400 ° C to 1300 ° C.
A soft ground improvement material that is heat-treated at a temperature of 300C for 3 to 120 minutes .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00887795A JP3526096B2 (en) | 1995-01-24 | 1995-01-24 | Soft ground improvement material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00887795A JP3526096B2 (en) | 1995-01-24 | 1995-01-24 | Soft ground improvement material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08199558A JPH08199558A (en) | 1996-08-06 |
| JP3526096B2 true JP3526096B2 (en) | 2004-05-10 |
Family
ID=11704916
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP00887795A Expired - Lifetime JP3526096B2 (en) | 1995-01-24 | 1995-01-24 | Soft ground improvement material |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3526096B2 (en) |
-
1995
- 1995-01-24 JP JP00887795A patent/JP3526096B2/en not_active Expired - Lifetime
Non-Patent Citations (1)
| Title |
|---|
| 小嶋他２名，コンクリート廃材から再生セメントの試製，第８５回学術講演会講演要旨，石膏石灰学会，１９９２年１０月８日，ｐ２２−２３ |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08199558A (en) | 1996-08-06 |
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