JP2014012930A - Estimation method of modified soil strength and manufacturing method of modified soil using the same - Google Patents
Estimation method of modified soil strength and manufacturing method of modified soil using the same Download PDFInfo
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本発明は、カルシウム化合物を含んだ改質材と泥土とを混合し、養生して強度を改質した改質土を得る際に、得られる改質土の強度を事前に予測する方法、及び、これを用いて改質土を製造する方法に関する。 The present invention is a method for predicting in advance the strength of the modified soil obtained when the modified material containing the calcium compound and the mud are mixed and cured to obtain the modified soil having a modified strength, and The present invention relates to a method for producing modified soil using the same.
浚渫工事や建設工事等で発生する泥土の強度を改良して、改質土として再利用することが行われている。これらの泥土は、主に水と土粒子とからなり、水と土粒子との質量比率（水／土粒子）で表される含水比が７０〜２５０％程度と極めて高いことから、ダンプトラック等に山積みして搬送するのは困難である。そのため、これまで泥土の処理が問題とされてきた。 The strength of mud generated in dredging and construction work is improved and reused as improved soil. These muds are mainly composed of water and soil particles, and the water content expressed by the mass ratio of water and soil particles (water / soil particles) is as high as about 70 to 250%. It is difficult to stack and transport them. Therefore, the treatment of mud has been a problem until now.
これに対し、近年では、泥土の強度を向上させる改質材を加えて混合し、干潟や浅場の造成工事に使用したり、海底の深堀れ窪地を処理するための埋め戻し工事に使用するなど、上述したように改質土としての利用が進んでいる。そのひとつに、改質材として製鋼スラグのほか、高炉水砕スラグや高炉スラグ微粉末を用いて改質土を得る方法が知られている（例えば特許文献１参照）。 On the other hand, in recent years, modifiers that improve the strength of mud are added and mixed, and used for the construction of tidal flats and shallow areas, and for backfilling work to treat deep sea depressions. As described above, utilization as reformed soil is progressing. As one of the methods, there is known a method of obtaining modified soil using blast furnace granulated slag or blast furnace slag fine powder in addition to steelmaking slag as a modifier (see, for example, Patent Document 1).
これは、改質材に含まれる遊離石灰（フリーライム：f-CaO）が、泥土に含まれるシリカ分と水和固化して、カルシウムシリケート系水和物（C-S-H）やカルシウムアルミネート系水和物（C-A-H）等を形成する反応を利用して、強度が改良されると考えられる。そして、上記特許文献１には、改質土の一軸圧縮強度とフリーライム量との間に強い相関関係があり、また、改質土の強度を発現させるためには少なくとも０．５質量％のフリーライム含有率が必要であることが記載されており、改質土の強度設計をする上で、改質材に含まれるフリーライム量がひとつの指標になる。 This is because free lime (f-CaO) contained in the modifier is hydrated and solidified with the silica contained in the mud, resulting in calcium silicate hydrate (CSH) and calcium aluminate hydrate. It is considered that the strength is improved by utilizing a reaction to form an object (CAH) or the like. And in the said patent document 1, there exists a strong correlation between the uniaxial compressive strength of modified soil, and the amount of free lime, and in order to express the strength of modified soil, at least 0.5 mass% It is described that a free lime content is necessary, and the amount of free lime contained in the reforming material is one index in designing the strength of the modified soil.
ところが、実際にフリーライム量に基づき泥土と改質材との配合設計を行っても、得られる改質土の一軸圧縮強度がばらつくことがあり、フリーライム量を指標とした改質土の強度予測は精度がさほど高くない。そのため、専ら、供試体を形成して所定の期間養生し、一軸圧縮強度を測定する強度試験に頼って、泥土と改質材の配合割合を決定しなければならない。 However, the uniaxial compressive strength of the modified soil obtained may vary even when the combination design of mud and modifier is actually based on the amount of free lime. The prediction is not very accurate. Therefore, it is necessary to determine the blending ratio of the mud and the modifying material exclusively by forming a specimen and curing it for a predetermined period of time and relying on a strength test for measuring the uniaxial compressive strength.
本発明は、このような従来技術の問題を鑑みてなされたものであり、カルシウム化合物を含んだ改質材と泥土とを混合し、養生して強度を改質した改質土を製造するにあたり、泥土と改質材との配合割合から発現する一軸圧縮強度を予測することができ、しかも、実際に得られた改質土のそれと高い精度で一致させることができる改質土の強度予測方法、及びこれを用いた改質土の製造方法を提供することを目的とする。 The present invention has been made in view of such problems of the prior art, and is used to produce a modified soil having a strength improved by mixing and curing a modifying material containing a calcium compound and mud. A method for predicting the strength of modified soil, which can predict the uniaxial compressive strength expressed from the blending ratio of mud and modified material, and can match with that of the actually obtained modified soil with high accuracy Another object of the present invention is to provide a method for producing modified soil using the same.
従来強度設計に利用されてきたフリーライム量に基づく一軸圧縮強度の予測精度が高くならない理由について、本発明者らは、その測定方法自体に原因があると考えた。すなわち、フリーライム量を測定するにあたり、一般には、セメント協会標準試験方法として定められるエチレングリコール法（JCAS I-01:1997）が使用されている。この方法では、指頭に感じない程度の細かさにすりつぶした細粉試料にエチレングリコールを加えて撹拌し、試料中の全ての遊離酸化カルシウム（f-CaO）を溶出させて、その含有率（％）を求める。 The present inventors considered that the measurement method itself has a reason why the prediction accuracy of the uniaxial compressive strength based on the amount of free lime that has been conventionally used for strength design is not high. That is, in measuring the amount of free lime, generally, the ethylene glycol method (JCAS I-01: 1997) defined as a standard test method of the Cement Association is used. In this method, ethylene glycol is added to a fine powder sample that has been ground to the extent that it cannot be felt by the fingertips, and stirred to elute all the free calcium oxide (f-CaO) in the sample. )
ところが、実際に改質土を得るのに使用する改質材は、エチレングリコール法での測定試料のようにすりつぶして細粉化することまでは行われず、粒度分布を有した状態で用いられる。そして、改質材の表面に存在する遊離酸化カルシウムは上述したような水和固化反応に利用されても、ある程度の大きさを有した改質材では、反応に利用されない遊離酸化カルシウムが内部に残されることが新たに判明した。 However, the modifying material actually used to obtain the modified soil is not used until it is ground and pulverized like a measurement sample in the ethylene glycol method, and is used in a state having a particle size distribution. Even if the free calcium oxide present on the surface of the modifying material is used for the hydration-solidification reaction as described above, in the modifying material having a certain size, free calcium oxide that is not used for the reaction is contained inside. It has been newly found that it remains.
そこで、本発明者らは、事前に改質材を水に入れて溶出するカルシウムイオンの量を測定し、これを指標にすることで、泥土と改質材との配合割合から実際に発現する改質土の一軸圧縮強度を精度良く予測することができることを見出し、本発明を完成させた。 Therefore, the inventors measured the amount of calcium ions eluted by putting the modifying material in water in advance, and using this as an index, it is actually expressed from the blending ratio of mud and modifying material. The present inventors have found that the uniaxial compressive strength of the modified soil can be accurately predicted.
すなわち、本発明の要旨は以下のとおりである。
（１）カルシウム化合物を含んだ改質材と泥土とを混合し、養生して強度を改質した改質土を得る際に、得られる改質土の強度を予測する方法であって、
２種以上の試験用の改質材を用意して、それぞれを水に入れて溶出するカルシウムイオンの単位質量あたりのカルシウムイオン溶出量を測定し、添加対象の泥土に対してそれぞれ試験用の改質材を混合して得られる各試験用改質土の一軸圧縮強度と前記カルシウムイオン溶出量との相関式を求めた上で、実際に泥土に添加する改質材の単位質量あたりのカルシウムイオン溶出量をもとに、事前に得た相関式から改質土の一軸圧縮強度を予測することを特徴とする改質土の強度予測方法。
（２）試験用の改質材、及び、実際に添加する改質材のカルシウムイオン溶出量を測定するにあたり、改質材と水との質量の割合が液固比１０の試験液とし、２４時間経過ごとに試験液のｐＨを測定して測定後は水を入れ替えるようにするカルシウムイオン溶出試験を養生日数に応じて行い、ｐＨ測定値からカルシウムイオン溶出量を換算する（１）に記載の改質土の強度予測方法。
（３）カルシウム化合物を含んだ改質材が、製鋼スラグ、高炉水砕スラグ、高炉スラグ微粉末、石灰、及びセメントからなる群から選ばれたいずれか１種又は２種以上である（１）又は（２）に記載の改質土の強度予測方法。
That is, the gist of the present invention is as follows.
(1) A method for predicting the strength of a modified soil obtained when a modified material containing a calcium compound and mud are mixed and cured to obtain a modified soil having improved strength,
Prepare two or more kinds of test modifiers, measure the calcium ion elution amount per unit mass of calcium ions to be eluted in water, and modify each test target for the mud to be added. After obtaining a correlation between the uniaxial compressive strength of each modified soil for testing obtained by mixing the material and the calcium ion elution amount, the calcium ions per unit mass of the modified material actually added to the mud A method for predicting the strength of modified soil, wherein the uniaxial compressive strength of the modified soil is predicted from a correlation equation obtained in advance based on the amount of elution.
(2) In measuring the calcium ion elution amount of the modifying material for testing and the modifying material actually added, the ratio of the mass of the modifying material to water is a test solution having a liquid-solid ratio of 10; According to (1), a calcium ion elution test is performed according to the number of days of curing, and the calcium ion elution amount is converted from the measured pH value by measuring the pH of the test solution over time and replacing water after the measurement. Strength prediction method for modified soil.
(3) The modifier containing the calcium compound is any one or more selected from the group consisting of steelmaking slag, granulated blast furnace slag, fine powder of blast furnace slag, lime, and cement (1) Or the strength prediction method of the modified soil as described in (2).
（４）前記（１）〜（３）のいずれかに記載の強度予測方法を用いて改質土を製造する方法であって、所望の一軸圧縮強度となるように、前記相関式に基づいてカルシウムイオンの溶出量を制御した改質材を泥土に混合し、養生して改質土を得ることを特徴とする改質土の製造方法。
（５）改質材の添加量を調整するか、改質材の種類を選択するか、２種以上の改質材を配合するか、改質材の粒度を調整するか、又は、これらの２つ以上を組み合わせることで、改質材からのカルシウムイオンの溶出量を制御する（４）に記載の改質土の製造方法。
(4) A method for producing modified soil using the strength prediction method according to any one of (1) to (3) above, based on the correlation equation so as to obtain a desired uniaxial compressive strength. A method for producing a modified soil, comprising mixing a modified material in which the amount of calcium ions eluted is mixed with mud and curing to obtain the modified soil.
(5) Adjust the additive amount of the modifier, select the type of modifier, blend two or more modifiers, adjust the particle size of the modifier, or these The method for producing modified soil according to (4), wherein the amount of calcium ions eluted from the modifying material is controlled by combining two or more.
本発明によれば、カルシウム化合物を含んだ改質材と泥土とを混合し、養生して強度を改質した改質土を製造するにあたり、実際に発現する改質土の一軸圧縮強度を高い精度で予測することができる。また、カルシウムイオンの溶出量を制御した改質材を泥土に混合することで、所望の一軸圧縮強度を有した改質土を任意に設計することが可能になり、かつ、従来に比べて容易に製造することができるようになる。 According to the present invention, when a modified material containing a calcium compound and mud are mixed and cured to improve the strength, the uniaxial compressive strength of the modified soil actually expressed is high. Can be predicted with accuracy. In addition, by mixing the modified material with controlled calcium ion elution amount into the mud, it becomes possible to arbitrarily design the modified soil having the desired uniaxial compressive strength, and easier than before. Will be able to be manufactured.
以下、本発明について詳細に説明する。
本発明においては、先ず、２種以上の試験用の改質材を用意して、それぞれを水に入れて溶出するカルシウムイオンの単位質量あたりの溶出量「カルシウムイオン溶出量」を測定する。このカルシウムイオン溶出量を測定するにあたっては、例えば、改質材と水との質量の割合を液固比（水／改質材）＝１０の試験液とし、２４時間経過ごとに試験液のｐＨを測定して測定後は水を入れ替えて新しい試験液にするカルシウムイオン溶出試験を養生日数に応じて行うようにする。
Hereinafter, the present invention will be described in detail.
In the present invention, first, two or more kinds of test modifiers are prepared, and the elution amount per unit mass of “calcium ion elution amount” of calcium ions to be eluted is measured. In measuring the calcium ion elution amount, for example, the ratio of the mass of the modifier to water is set to a test solution with a liquid-solid ratio (water / modifier) = 10, and the pH of the test solution is measured every 24 hours. After the measurement, the calcium ion elution test is carried out according to the number of days of curing.
ここで、好適には水として蒸留水を使用するのがよく、また、２４時間経過時にｐＨ測定する際には、その都度試験液を撹拌してからｐＨを測定するようにしてもよい。更には、例えば試験開始から１〜７日目までは上記のようなｐＨ測定を毎日実施し、その後はカルシウムイオンの溶出量がある程度飽和することを見越して１０日目、１４日目、１９日目、２１日目、及び２８日目にｐＨ測定を行うようにするなど、養生日数に応じたカルシウムイオン溶出試験を行うようにすればよい。 Here, it is preferable to use distilled water as water, and when the pH is measured when 24 hours have elapsed, the pH may be measured after stirring the test solution each time. Further, for example, the pH measurement as described above is performed every day from the start of the test to the first to seventh days, and thereafter, the 10th day, the 14th day, and the 19th day in anticipation that the elution amount of calcium ions is saturated to some extent. What is necessary is just to make it carry out the calcium ion elution test according to the curing days, such as making pH measurement on the eyes, the 21st day, and the 28th day.
そして、試験液のｐＨ上昇は全て改質材から溶出するカルシウムイオン（Ca2+）によるものとして、下記式（１）に基づいて、ｐＨ上昇分の総和から単位質量あたりのカルシウムイオン溶出量〔Ca2+溶出量（mol/kg）〕を求めることができる。
一方で、添加対象の泥土に対してそれぞれ試験用の改質材を混合して得られる各試験用改質土の一軸圧縮強度を測定する。その際、実際に目的の改質土を得る場合と同じ日数で養生するようにすればよい。そして、得られた試験用改質土の一軸圧縮強度と前述のカルシウムイオン溶出量との関係から「一軸圧縮強度−カルシウムイオン溶出量」の相関式を求めるようにする。これらは一次関数で表されるような良好な相関性が認められる。 On the other hand, the uniaxial compressive strength of each modified soil for testing obtained by mixing the modified material for testing with the mud soil to be added is measured. At that time, curing may be performed in the same number of days as when the desired modified soil is actually obtained. Then, a correlation formula of “uniaxial compressive strength−calcium ion elution amount” is obtained from the relationship between the uniaxial compressive strength of the obtained modified soil for testing and the aforementioned calcium ion elution amount. These have a good correlation as expressed by a linear function.
そのため、目的の改質土を得る際には、実際に泥土に添加する改質材のカルシウムイオン溶出量を前述のカルシウムイオン溶出試験等によって予め求めておけば、この相関式から改質土の一軸圧縮強度を精度良く予測することができる。 Therefore, when obtaining the target modified soil, if the calcium ion elution amount of the modifier actually added to the mud is previously determined by the calcium ion elution test, etc. Uniaxial compressive strength can be accurately predicted.
本発明で用いる泥土は、主に水と土粒子とからなり、浚渫土や建設排土等を例示することができる。このうち浚渫土は、港湾、河川、運河等の航路や泊地を拡げる目的や、河川、湖沼、ダム等の水底や海底の汚泥・底質汚染を除去する目的等を含めて、総じて浚渫により生じたものである。また、建設排土は、掘削等の建設工事で排出されたものである。これらはいずれも、その高い含水比（一般には含水比70〜250％程度）によって、ダンプトラック等に山積みして搬送するのが困難であったり、その上を人が歩けない程度のものであり、このような高含水比の泥土を用いて、改質土を得ることができる。 The mud used in the present invention is mainly composed of water and soil particles, and examples thereof include dredged soil and construction soil. Of these, dredged soil is generally generated by dredging, including the purpose of expanding the routes and anchorage of ports, rivers, canals, etc., and the purpose of removing sludge and sediment from the bottom of the river, lakes, dams, etc. It is a thing. In addition, construction soil is discharged from construction work such as excavation. All of these are difficult to pile on a dump truck etc. due to their high water content (generally about 70-250%), or on which people cannot walk. The modified soil can be obtained using such a high water content mud.
また、改質材としては、カルシウム化合物を含んでカルシウムイオンを溶出するものであればよく、例えば、製鋼スラグ、高炉水砕スラグ、高炉スラグ微粉末、石灰、セメント等を例示することができる。これらは１種又は２種以上を混ぜて使用することができる。 Moreover, as a modifier, what is necessary is just to include a calcium compound and to elute calcium ion, for example, steelmaking slag, granulated blast furnace slag, blast furnace slag fine powder, lime, cement etc. can be illustrated. These can be used alone or in combination of two or more.
ここで、製鋼スラグとは、鉄鋼製造プロセスで副産物として産出されるものであり、転炉や電気炉等の製鋼炉において、銑鉄やスクラップから不要な成分を除去して、靭性・加工性のある鋼にする製鋼工程で生じる石灰分を主体としたものである。具体的には、転炉スラグ、予備処理スラグ、脱炭スラグ、脱燐スラグ、脱硫スラグ、脱珪スラグ、電気炉還元スラグ、電気炉酸化スラグ、二次精錬スラグ、造塊スラグ等を挙げることができる。 Here, steelmaking slag is produced as a by-product in the steelmaking process, and in steelmaking furnaces such as converters and electric furnaces, it removes unnecessary components from pig iron and scrap and has toughness and workability. It is mainly composed of lime produced in the steel making process. Specifically, converter slag, pretreatment slag, decarburization slag, dephosphorization slag, desulfurization slag, desiliconization slag, electric furnace reduction slag, electric furnace oxidation slag, secondary refining slag, ingot slag, etc. Can do.
また、高炉水砕スラグとは、銑鉄を製造する製銑過程で生成する溶融状態の高炉スラグに加圧水を噴射するなどして水砕し、急激に冷却したものである。更に、高炉スラグ微粉末は、この高炉水砕スラグを微粉砕したものである。 The blast furnace granulated slag is water granulated by, for example, spraying pressurized water onto a molten blast furnace slag produced in the iron making process for producing pig iron and rapidly cooling. Furthermore, the blast furnace slag fine powder is obtained by finely pulverizing this granulated blast furnace slag.
そして、カルシウム化合物を含んだ改質材と泥土とを混合して改質土を得るにあたり、事前に求めた相関式に基づいてカルシウムイオンの溶出量を制御した改質材を泥土に混合すれば、自由に一軸圧縮強度を設計しながら目的の改質土を製造することができる。すなわち、改質材の添加量を調製するか、改質材の種類を選択するか、２種以上の改質材を配合するか、改質材の粒度を調整するか、又は、これらの２つ以上を組み合わせることで改質材からのカルシウムイオンの溶出量を制御することができ、必要に応じて加重平均するなどして泥土と改質材との配合割合を決めれば、任意の一軸圧縮強度を発現する改質土が製造可能になる。 Then, when the modified material containing calcium compound and mud are mixed to obtain the modified soil, the modified material with controlled calcium ion elution amount based on the correlation equation obtained in advance is mixed with the mud. The desired modified soil can be produced while freely designing the uniaxial compressive strength. That is, the amount of the modifier added is adjusted, the type of modifier is selected, two or more modifiers are blended, the particle size of the modifier is adjusted, or these 2 By combining two or more, the elution amount of calcium ions from the modifier can be controlled, and if the blending ratio of mud and modifier is determined by weighted averaging if necessary, etc., arbitrary uniaxial compression Modified soil that exhibits strength can be manufactured.
改質材と泥土とを混合する手段については特に制限されず、公知の方法を採用することができる。また、混合した後の養生方法については、気中養生、水中養生等の一般的な改質土を得るための方法を用いることができ、用途等に応じて養生日数を適宜選択すればよい。 The means for mixing the modifier and the mud is not particularly limited, and a known method can be adopted. Moreover, about the curing method after mixing, the method for obtaining general modified soils, such as an air curing and an underwater curing, can be used, and the curing days should just be selected suitably according to a use etc.
本発明によって得られた改質土は、例えば、海域の潜堤を構築したり、干潟や浅場の造成工事に使用することができるほか、深堀れ窪地を処理する埋め戻し工事や埋め立て用の地盤形成など、水域や陸域環境の修復工事に好適に利用することができる。 The modified soil obtained by the present invention can be used for, for example, constructing a submerged dike in the sea area, construction work for tidal flats and shallow areas, as well as backfilling work for processing deep trenches and ground for landfilling. It can be suitably used for water and land environment restoration works such as formation.
［実施例１］
泥土として、表１に示したように、異なる場所の海底から回収された３種類の浚渫土Ｉ〜IIIを用意した。ここで、表中の細粒分含有率とは、JIS A 1223 土の細粒分含有率試験方法から得られた値である。強熱減量はJIS A 1226に準拠する強熱減量試験から得られた値である。フロー値は日本道路公団規格「エアモルタル及びエアミルクの試験方法（JHS A 3113-1992）のコンシステンシー試験方法に定められた測定結果を示す。ベーンせん断強度は、JGS 1411 原位置ベーンせん断試験方法より求めたものである。液性限界、塑性限界、及び塑性指数は、JIS A 1205 土の液性限界・塑性限界試験方法より求めたものである。
[Example 1]
As mud soil, as shown in Table 1, three types of dredged soils I to III recovered from the seabed at different locations were prepared. Here, the fine particle content in the table is a value obtained from the fine particle content test method of JIS A 1223 soil. The ignition loss is a value obtained from an ignition loss test according to JIS A 1226. The flow value shows the measurement result stipulated in the consistency test method of the Japan Highway Public Corporation Standard “Air Mortar and Air Milk Test Method (JHS A 3113-1992). Vane shear strength is based on JGS 1411 in-situ vane shear test method The liquid limit, the plastic limit, and the plasticity index are obtained from the liquid limit / plastic limit test method of JIS A 1205 soil.
また、カルシウム化合物を含んだ改質材として、表２に示したように、製鐵所で回収した５種類の製鋼スラグａ〜ｅを用意した。これらはいずれもJIS A 1125 ふるい分け試験により粒度を調整し、JIS A 5015「道路用鉄鋼スラグ」に基づくCS-20の規格を満たすものである。これはJIS Z 8801の網ふるいの呼び寸法によりふるいを通るものの質量百分率（％）が規定された（26.5mm：100％、19mm：95〜100％、13.2mm：60〜90％、4.75mm：20〜50％、2.36mm：10〜35％）、粒度範囲20〜0mmのものである。また、フリーライム（f-CaO）の含有量は、エチレングリコール法（JCAS I-01:1997）に基づき測定した値であり、それぞれの製鋼スラグをめのう乳鉢ですりつぶした後、８０℃に加熱したエチレングリコールを加え、更にフェノールフタレイン指示薬を数滴加えて撹拌しながら遊離酸化カルシウムを５分間溶出させ、酢酸アンモニウム標準液で滴定して求めた。 Moreover, as shown in Table 2, five types of steelmaking slags a to e collected at the steelworks were prepared as modifiers containing calcium compounds. All of these meet the CS-20 standard based on JIS A 5015 “Steel Slag for Roads” by adjusting the particle size by JIS A 1125 screening test. This is based on the nominal size of the screen sieve of JIS Z 8801, and the mass percentage (%) of what passes through the screen is specified (26.5mm: 100%, 19mm: 95-100%, 13.2mm: 60-90%, 4.75mm: 20 to 50%, 2.36 mm: 10 to 35%) and a particle size range of 20 to 0 mm. The content of free lime (f-CaO) is a value measured based on the ethylene glycol method (JCAS I-01: 1997). Each steelmaking slag was ground in an agate mortar and then heated to 80 ° C. Ethylene glycol was added, a few drops of phenolphthalein indicator was added, free calcium oxide was eluted for 5 minutes with stirring, and titrated with an ammonium acetate standard solution.
更には、製鋼スラグａ〜ｅについて、それぞれを蒸留水に入れて溶出するカルシウムイオンの単位質量あたりのカルシウムイオン溶出量（mol/kg）を以下のようにして測定した。先ず、５リットル容器に蒸留水（pH=6.5）を４リットル入れ、これに製鋼スラグを４００ｇ加えて液固比１０の試験液とした（製鋼スラグの種類ごとに５つ準備した）。そして、２４時間経過した時点で１回／秒の周期で容器内を１０回撹拌してから試験液のｐＨを測定した。ｐＨ測定後は蒸留水を入れ替えて再度試験液を調製し、再び２４時間経過したところで、上記と同様に撹拌、試験液のｐＨ測定、及び蒸留水の入れ替えを行うようにし、試験開始から１〜７日目まではこれらの操作を毎日実施し、その後は１０日目、１４日目、１９日目、２１日目、及び２８日目に実施するカルシウムイオン溶出試験を行った。そして、合計１２回のｐＨ測定の結果から、前述の式（１）を使って製鋼スラグａ〜ｅのそれぞれの２８日経過後のカルシウムイオン溶出量（Ca2+溶出量）を求めた。結果を表２に示す。 Furthermore, about the steelmaking slag ae, the calcium ion elution amount (mol / kg) per unit mass of the calcium ion which puts each in distilled water and elutes was measured as follows. First, 4 liters of distilled water (pH = 6.5) was placed in a 5 liter container, and 400 g of steelmaking slag was added thereto to prepare a test solution having a liquid-solid ratio of 10 (five prepared for each type of steelmaking slag). And when 24 hours passed, the inside of the container was stirred 10 times at a cycle of 1 time / second, and then the pH of the test solution was measured. After the pH measurement, distilled water was replaced and the test solution was prepared again. After 24 hours had passed again, stirring, pH measurement of the test solution, and replacement of distilled water were performed in the same manner as described above. These operations were carried out every day until the seventh day, and thereafter, calcium ion elution tests were conducted on the 10th, 14th, 19th, 21st, and 28th days. Then, from the results of a total of 12 times measured pH was determined calcium ion elution amount of each of 28 days after the steel slag a~e using equation (1) described above (Ca 2+ elution volume). The results are shown in Table 2.
上記で準備した１８．１２ｋｇの浚渫土Ｉと１４．５８ｋｇの製鋼スラグａとを、２軸強制練りミキサーを用いて撹拌混合した後、φ１００ｍｍ×Ｌ２００ｍｍのモールドに詰めて成型し、２０℃、湿度６０％の恒温室で２８日間気中養生して試験用改質土Ｉ-ａを得た。このようにして得られた試験用改質土Ｉ-ａについて一軸圧縮強度を測定し、サンプル数３（n=3）としてその平均を求めたところ、一軸圧縮強度の平均値は７６１．５２ｋＮ／ｍ2であった。浚渫土と製鋼スラグの組み合わせを変え、上記と同様にして試験用改質土Ｉ-ａ〜Ｉ-ｅ、II-ａ〜II-ｅ、III-ａ〜III-ｅを作製して、一軸圧縮強度の平均値（n=3）を求めた。結果を表３に示す。 18.12 kg of clay I prepared above and 14.58 kg of steelmaking slag a were mixed with stirring using a biaxial forced kneading mixer, then packed into a mold of φ100 mm × L200 mm, molded at 20 ° C., humidity A modified soil Ia for testing was obtained by air curing in a 60% constant temperature room for 28 days. The test modified soil Ia thus obtained was measured for uniaxial compressive strength, and the average was calculated as 3 samples (n = 3). The average uniaxial compressive strength was 761.52 kN / m 2 . By changing the combination of dredged soil and steelmaking slag, test modified soils Ia to Ie, II-a to II-e, III-a to III-e were produced in the same manner as above and uniaxially compressed. The average intensity (n = 3) was determined. The results are shown in Table 3.
そして、浚渫土の種類ごとに、得られた試験用改質土の平均一軸圧縮強度（kN/m2）と製鋼スラグのカルシウムイオン溶出量（mol/kg）との関係をグラフにすると図１のとおりになり、いずれも良好な相関性を示した。すなわち、ｙ軸を平均一軸圧縮強度とし、ｘ軸をカルシウムイオン溶出量（Ca2+溶出量）とすれば、浚渫土Ｉについては「式Ｉ：ｙ＝2519.1ｘ−252.05」、浚渫土IIについては「式II：ｙ＝208.39ｘ−35.91」、浚渫土IIIについては「式III：ｙ＝1083.3ｘ−170.37」の一次関数でそれぞれ表すことができる。これらによれば、実際に添加する改質材の単位質量あたりのカルシウムイオン溶出量をもとに、浚渫土Ｉ〜IIIのいずれかに係る相関式から、得られる改質土の一軸圧縮強度を予測することが可能になる。 For each type of dredged soil, the relationship between the average uniaxial compressive strength (kN / m 2 ) of the obtained test modified soil and the calcium ion elution amount (mol / kg) of the steelmaking slag is shown in a graph in FIG. As a result, both showed good correlation. That is, assuming that the y-axis is the average uniaxial compressive strength and the x-axis is the calcium ion elution amount (Ca 2+ elution amount), the formula I: “y = 2519.1x−252.05” and the clay II Can be expressed by a linear function of “Formula II: y = 208.39 × −35.91”, and the clay III can be expressed by a linear function of “Formula III: y = 1083.3x−170.37”. According to these, based on the calcium ion elution amount per unit mass of the modifier to be actually added, the uniaxial compressive strength of the obtained modified soil is obtained from the correlation equation according to any one of the clays I to III. It becomes possible to predict.
一方で、カルシウムイオン溶出量の代わりにフリーライム量をｘ軸にすると図２のとおりになり、図１の場合に比べて相関性は劣ることが分かる。なお、図２においては、製鋼スラグの一粒を球と仮定し、球の比表面積×f-CaO量＝f-CaO量含有率として各製鋼スラグに含まれる累積フリーライム量（％）を用いている。 On the other hand, when the amount of free lime is set on the x-axis instead of the calcium ion elution amount, the result is as shown in FIG. In addition, in FIG. 2, one grain of steelmaking slag is assumed to be a sphere, and the cumulative free lime amount (%) contained in each steelmaking slag is used as the specific surface area of the sphere × f-CaO amount = f-CaO amount content. ing.
［実施例２］
改質材として下記表４に示した３種類の製鋼スラグｆ〜ｈを用意した。これらの製鋼スラグは、いずれも粒径３０〜０ｍｍのものである。また、泥土としては、大阪湾で回収された浚渫土IV（含水比160質量％、湿潤密度1.304g/cm3）を使用した。そして、製鋼スラグｆ〜ｈについて、実施例１の場合と同様にして２８日経過後のカルシウムイオン溶出量（Ca2+溶出量）を求めた。結果を表４に示す。
[Example 2]
Three types of steelmaking slags f to h shown in Table 4 below were prepared as modifiers. Each of these steelmaking slags has a particle size of 30 to 0 mm. As mud, dredged soil IV (water content 160 mass%, wet density 1.304 g / cm 3 ) collected in Osaka Bay was used. And about the steelmaking slags f-h, it carried out similarly to the case of Example 1, and calculated | required the calcium ion elution amount (Ca2 + elution amount) after 28-day progress. The results are shown in Table 4.
上記で準備した製鋼スラグｆ〜ｇについて、下記表５の配合名１〜３に示したように、製鋼スラグ９リットルに対して浚渫土IVが２１リットル（27.384kg）となるように、それぞれの製鋼スラグと浚渫土IVとの容積比を３０％：７０％として、２軸強制練りミキサーを用いてそれぞれ撹拌混合した（各混練量30リットル）。次いで、得られた混練物をそれぞれφ１００ｍｍ×Ｌ２００ｍｍのモールドに詰めて成型し、２０℃、湿度６０％の恒温室で２８日間気中養生して試験用改質土を得た。そして、各配合で得られた試験用改質土の一軸圧縮強度を測定し、それぞれサンプル数３（n=3）としてその平均を求めた。結果を表５に示す。 About the steelmaking slags f to g prepared above, as shown in the compound names 1 to 3 in Table 5 below, the clay IV is 21 liters (27.384 kg) with respect to 9 liters of the steelmaking slag. The volume ratio of steelmaking slag and clay IV was 30%: 70%, and each was stirred and mixed using a biaxial forced kneading mixer (each kneading amount 30 liters). Next, the obtained kneaded materials were each packed in a mold of φ100 mm × L200 mm, molded, and cured in air in a temperature-controlled room at 20 ° C. and 60% humidity for 28 days to obtain modified soil for testing. And the uniaxial compressive strength of the test modified soil obtained by each mixing | blending was measured, and the average was calculated | required as the number of samples 3 (n = 3), respectively. The results are shown in Table 5.
上記配合名１〜３で得られた試験用改質土の平均一軸圧縮強度（kN/m2）と製鋼スラグｆ〜ｈのカルシウムイオン溶出量（mol/kg）との関係をグラフにすると図３のようになり、ｙ軸を平均一軸圧縮強度とし、ｘ軸をカルシウムイオン溶出量とすれば、浚渫土IVについてｙ＝328.67ｘ−127.16の相関式IVを得ることがで
きた。
A graph showing the relationship between the average uniaxial compressive strength (kN / m 2 ) of the modified soil for testing obtained with the above blend names 1 to 3 and the calcium ion elution amount (mol / kg) of the steelmaking slags f to h is shown in the graph. When the y-axis is the average uniaxial compressive strength and the x-axis is the calcium ion elution amount, the correlation formula IV of y = 328.67x−127.16 can be obtained for the clay IV.
上記で得られた相関式IVによれば、浚渫土IVから１００ｋＮ／ｍ2の改質土を得るためには、０．７ｍｏｌ／ｋｇのカルシウムイオン溶出量を有する改質材が必要であると考えられる。そこで、表４に示したカルシウムイオン溶出量に基づき、製鋼スラグｆを５６質量％、製鋼スラグｇを１４質量％、及び製鋼スラグｈを３０質量％の配合割合にして、２７．３８４ｋｇ（21リットル）の浚渫土IVに対して、１６．７４７ｋｇの製鋼スラグｆ、４．１８７ｋｇの製鋼スラグｇ、及び８．９７２ｋｇの製鋼スラグｈを加えて配合すると、計算上のカルシウムイオン溶出量は０．６６８８ｍｏｌ／ｋｇとなり、その場合、相関式IVによれば目標強度９９．６２２３ｋＮ／ｍ2の改質土が得られることになる。 According to the correlation equation IV obtained above, in order to obtain a modified soil of 100 kN / m 2 from the clay IV, a modifying material having a calcium ion elution amount of 0.7 mol / kg is necessary. Conceivable. Therefore, based on the calcium ion elution amount shown in Table 4, the steelmaking slag f is 56% by mass, the steelmaking slag g is 14% by mass, and the steelmaking slag h is 30% by mass, and 27.384 kg (21 liters). When the steelmaking slag f of 16.747 kg, the steelmaking slag g of 4.187 kg, and the steelmaking slag h of 8.972 kg are added and mixed with the clay IV of), the calculated calcium ion elution amount is 0.6688 mol. In this case, the modified soil having the target strength of 99.6223 kN / m 2 is obtained according to the correlation equation IV.
そこで、表５に示した配合名４について、試験用改質土を得た場合と同様にして２軸強制練りミキサーで撹拌混合し、φ１００ｍｍ×Ｌ２００ｍｍのモールドに詰めて２０℃、湿度６０％の恒温室で２８日間気中養生して配合名４に係る改質土を得た。そして、得られた改質土の一軸圧縮強度を測定したところ９９ｋＮ／ｍ2であり、目標強度に近い改質土を製造することができた。
Therefore, for the
Claims (5)
２種以上の試験用の改質材を用意して、それぞれを水に入れて溶出するカルシウムイオンの単位質量あたりのカルシウムイオン溶出量を測定し、添加対象の泥土に対してそれぞれ試験用の改質材を混合して得られる各試験用改質土の一軸圧縮強度と前記カルシウムイオン溶出量との相関式を求めた上で、実際に泥土に添加する改質材の単位質量あたりのカルシウムイオン溶出量をもとに、事前に得た相関式から改質土の一軸圧縮強度を予測することを特徴とする改質土の強度予測方法。 A method of predicting the strength of the modified soil obtained when the modified material containing a calcium compound and mud are mixed and cured to obtain modified soil having improved strength,
Prepare two or more kinds of test modifiers, measure the calcium ion elution amount per unit mass of calcium ions to be eluted in water, and modify each test target for the mud to be added. After obtaining a correlation between the uniaxial compressive strength of each modified soil for testing obtained by mixing the material and the calcium ion elution amount, the calcium ions per unit mass of the modified material actually added to the mud A method for predicting the strength of modified soil, wherein the uniaxial compressive strength of the modified soil is predicted from a correlation equation obtained in advance based on the amount of elution.
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