JP5728845B2 - Method for estimating strength of modified dredged soil and method for modifying dredged soil - Google Patents
Method for estimating strength of modified dredged soil and method for modifying dredged soil Download PDFInfo
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- JP5728845B2 JP5728845B2 JP2010171237A JP2010171237A JP5728845B2 JP 5728845 B2 JP5728845 B2 JP 5728845B2 JP 2010171237 A JP2010171237 A JP 2010171237A JP 2010171237 A JP2010171237 A JP 2010171237A JP 5728845 B2 JP5728845 B2 JP 5728845B2
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- 238000000034 method Methods 0.000 title claims description 44
- 239000002689 soil Substances 0.000 title claims description 25
- 239000002893 slag Substances 0.000 claims description 168
- 238000009628 steelmaking Methods 0.000 claims description 132
- 239000000463 material Substances 0.000 claims description 116
- 239000004927 clay Substances 0.000 claims description 113
- 239000002245 particle Substances 0.000 claims description 81
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 40
- 239000000920 calcium hydroxide Substances 0.000 claims description 40
- 235000011116 calcium hydroxide Nutrition 0.000 claims description 40
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 40
- 238000002156 mixing Methods 0.000 claims description 37
- 239000000203 mixture Substances 0.000 claims description 23
- 238000012360 testing method Methods 0.000 claims description 15
- 229910000831 Steel Inorganic materials 0.000 claims description 12
- 239000010959 steel Substances 0.000 claims description 12
- 239000007787 solid Substances 0.000 claims description 7
- 238000002407 reforming Methods 0.000 claims description 6
- 239000000292 calcium oxide Substances 0.000 description 34
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 34
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- 239000011575 calcium Substances 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 12
- 238000013461 design Methods 0.000 description 12
- 239000003153 chemical reaction reagent Substances 0.000 description 7
- 238000005261 decarburization Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
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- 239000004568 cement Substances 0.000 description 5
- 239000000377 silicon dioxide Substances 0.000 description 5
- 238000011161 development Methods 0.000 description 4
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- 238000005259 measurement Methods 0.000 description 3
- 230000009257 reactivity Effects 0.000 description 3
- 238000007711 solidification Methods 0.000 description 3
- 230000008023 solidification Effects 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
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- 238000004458 analytical method Methods 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 238000005219 brazing Methods 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
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- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
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- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
- Soil Conditioners And Soil-Stabilizing Materials (AREA)
Description
本発明は、軟弱な浚渫土を海域などで有効利用するために、製鋼スラグを混合して浚渫土の強度改質を行う技術において、浚渫土と製鋼スラグの混合材の強度を的確に推定することができる強度推定方法と、浚渫土に対する製鋼スラグの適正な混合量を決定することができる浚渫土の改質方法に関する。 The present invention accurately estimates the strength of a mixed material of dredged soil and steelmaking slag in a technique for modifying the strength of dredged soil by mixing steelmaking slag in order to effectively use soft dredged soil in the sea area. The present invention relates to a strength estimation method that can be used, and a method for modifying a clay that can determine an appropriate mixing amount of steelmaking slag with respect to the clay.
水質環境改善などを目的として、浅場や干潟の造成が行われている。従来、浅場や干潟の造成は、砕石を用いて沖合に土留め潜堤を設置した後、その岸側(陸側)に中詰材として浚渫土を設置し、その表層に天然砂を覆砂するような工法が採られている。
これに対して、特許文献1には、鉄鋼スラグに含まれるCaO分を積極的に活用し、浚渫土に鉄鋼スラグを混合して強度改質を行う技術が示されている。この技術では、主に鉄鋼スラグのCaO分と浚渫土のSi、Al等とのポゾラン反応により、浚渫土の強度改質を行うものである。この特許文献1では、使用する鉄鋼スラグの遊離CaO量や浚渫土に対する混合割合などについて詳細な検討がなされ、強度改質に好適な条件が示されている。
For the purpose of improving the water quality environment, shallow areas and tidal flats are being created. Conventionally, shallow ground and tidal flats have been constructed by using a crushed stone to install an earth retaining submarine offshore, and then installing dredged soil as a filling material on the shore side (land side) and covering the surface with natural sand. Such a construction method is adopted.
On the other hand, Patent Document 1 discloses a technique for performing strength modification by actively utilizing the CaO content contained in the steel slag and mixing the steel slag with the clay. In this technique, the strength of the clay is improved mainly by a pozzolanic reaction between the CaO content of the steel slag and Si, Al, etc. of the clay. In this patent document 1, detailed examination is made about the amount of free CaO of steel slag to be used and the mixing ratio with respect to the clay, and conditions suitable for strength modification are shown.
しかしながら、特許文献1の技術について、本発明者がさらに検討を進めたところ、製鋼スラグの種類や混合割合を同じ条件にしても、混合材(浚渫土+製鋼スラグ)によって強度発現挙動が全く異なる場合があることが判った。また、同じ浚渫土に対して類似した製鋼スラグを混合した場合ですら、強度が変動する場合も見られた。
浚渫土と製鋼スラグの混合材が単純に固化するかどうかだけであれば、特許文献1の技術でも特に問題はないが、構造的に強度が必要な場合や、生物着生しやすい強度に設計する場合など、特定の強度が望まれるケースもある。そのような場合、適切な強度を確保できるように条件を設定する必要があるが、上記のように特許文献1の技術では想定通りの強度を得ることが難しく、さまざまな実験を繰り返して強度を経験的に設定するしかなかった。
However, when the inventor further studied the technique of Patent Document 1, even if the type and mixing ratio of the steelmaking slag are the same, the strength development behavior is completely different depending on the mixed material (kneaded clay + steeling slag). It turns out that there is a case. In addition, even when similar steelmaking slag was mixed for the same clay, the strength could be seen to change.
As long as the mixed material of the clay and steelmaking slag is simply solidified, there is no particular problem with the technique of Patent Document 1, but it is designed to be structurally strong or easy to grow. In some cases, a specific strength is desired. In such a case, it is necessary to set conditions so that an appropriate strength can be ensured. However, as described above, it is difficult to obtain the expected strength with the technique of Patent Document 1, and the strength is increased by repeating various experiments. I had to set it empirically.
したがって本発明の目的は、製鋼スラグを混合して浚渫土の強度改質を行う際に、浚渫土と製鋼スラグの混合材の強度を的確に推定することができ、これにより改質浚渫土の適正な強度設計を実現することができる、改質浚渫土の強度推定方法を提供することにある。
また、本発明の他の目的は、製鋼スラグを混合して浚渫土の強度改質を行う際に、設計強度に応じた製鋼スラグの適正な混合量を決定することができる浚渫土の改質方法を提供することにある。
Therefore, the object of the present invention is to accurately estimate the strength of the mixed material of the clay and the steelmaking slag when the steelmaking slag is mixed to improve the strength of the clay. An object of the present invention is to provide a method for estimating the strength of the modified clay, which can realize an appropriate strength design.
In addition, another object of the present invention is to improve the dredged soil that can determine the appropriate mixing amount of the steel-making slag according to the design strength when the steel-making slag is mixed to modify the dredged strength. It is to provide a method.
本発明は、上記課題を解決するために、浚渫土と製鋼スラグのさまざまな固有特性と混合後の固化挙動を解析した結果、いくつかの重要な物性に基づくことで、改質浚渫土の固化後の強度を的確に推定することができ、これにより適正な強度設計を実現できることが判った。したがって、これを利用することで、設計強度に応じた製鋼スラグの適正な混合量も決定できることが判った。
浚渫土と製鋼スラグの固化反応は、製鋼スラグからのCaイオン、OHイオンの供給量と浚渫土からのSi浸出量に関係があると考えられている。本発明者らがさらに詳細に検討した結果、浚渫土のSi分は溶液に浸出する必然性はなく、浚渫土の表面で反応性が高ければよいことが判った。すなわち、浚渫土の微粒子分が多ければ反応性が高くなり、強度が高まり易いことが判った。一方、浚渫土中の微粒子分は、Ca分を吸着する効果もあることが知られている。本発明者らが検討した結果、浚渫土に製鋼スラグを混合した場合、製鋼スラグから供給されるCa分のうち、ある特定量のCa吸着が終わった後に、安定した強度発現が実現できることが判った。さらに、反応する対象の製鋼スラグについては、CaO量などの成分組成よりも遊離CaO含有量の影響が極めて大きく、加えて、粒径2mm以下のスラグ粒子の比率が重要であることが判った。そして、これらの要因を考慮した推定式を用いることにより、様々な確性実験を行うことなく、浚渫土と製鋼スラグの混合材の強度を的確に推定することができ、混合材の適正な強度設計を実現できることが判った。また、このようなことから、混合材の設計強度に応じて最適な製鋼スラグ(組成、粒度)を選択するとともに、浚渫土に対する製鋼スラグの適正な混合量を決定できることが判った。
In order to solve the above-mentioned problems, the present invention has analyzed the various intrinsic properties of the clay and steelmaking slag and the solidification behavior after mixing. As a result, the solidification of the modified clay is based on several important physical properties. It was found that the later strength can be accurately estimated, and thus an appropriate strength design can be realized. Therefore, it was found that by using this, an appropriate mixing amount of the steelmaking slag according to the design strength can be determined.
The solidification reaction between the clay and the steelmaking slag is considered to be related to the supply amount of Ca ions and OH ions from the steelmaking slag and the amount of Si leaching from the clay. As a result of further detailed studies by the present inventors, it was found that the Si content of the clay does not necessarily leached into the solution, and it is sufficient that the reactivity is high on the surface of the clay. That is, it was found that the more fine particles of the kneaded material, the higher the reactivity and the easier the strength. On the other hand, it is known that the fine particles in the clay also have an effect of adsorbing Ca. As a result of the study by the present inventors, when steelmaking slag is mixed with clay, it has been found that stable strength expression can be realized after a certain amount of Ca adsorption is finished in the Ca component supplied from the steelmaking slag. It was. Furthermore, it has been found that the steel slag to be reacted is much more influenced by the free CaO content than the component composition such as the CaO amount, and in addition, the ratio of slag particles having a particle size of 2 mm or less is important. And by using the estimation formula considering these factors, the strength of the mixed material of clay and steelmaking slag can be accurately estimated without performing various accuracy experiments, and the appropriate strength design of the mixed material It was found that can be realized. Moreover, it turned out that the optimal mixing amount of the steelmaking slag with respect to the clay can be determined while selecting the optimum steelmaking slag (composition, particle size) according to the design strength of the mixed material.
本発明はこのような知見に基づきなされたもので、以下を要旨とするものである。
[1]製鋼スラグを混合して浚渫土の改質を行う際に、浚渫土と製鋼スラグの混合材(x)の強度を推定する方法であって、下記(1)式に基づき、混合材(x)の28日養生後の一軸圧縮強度の推定値f(N/cm2)を求めることを特徴とする改質浚渫土の強度推定方法。
f=α×Ds×Sg×{(Co−Ch)/Wa} …(1)
但し
Ds=[混合材(x)中の粒径0.075mm以下の浚渫土粒子の質量]/[混合材(x)の固形分の質量]×100(%)
Sg=[混合材(x)中の粒径2mm以下の製鋼スラグ粒子の質量]/[混合材(x)の製鋼スラグの質量]×100(%)
Ch:事前の試験において、改質対象である浚渫土に消石灰を混合し、その混合材の28日養生後の一軸圧縮強度が50kN/m2となる場合の混合材1m3中の消石灰の質量(kg)×1.5
Co:製鋼スラグが含有する遊離CaOであって、混合材(x)1m3中の遊離CaOの質量(kg)
Wa:混合材(x)1m3中の水分の質量(kg)
α:3.6
The present invention has been made on the basis of such findings and has the following gist.
[1] A method for estimating the strength of the mixed material (x) of the clay and the steelmaking slag when the steelmaking slag is mixed and reforming the clay, and based on the following formula (1) A method for estimating the strength of the modified dredged material, characterized in that an estimated value f (N / cm 2 ) of the uniaxial compressive strength after the 28-day curing of (x) is obtained.
f = α × Ds × Sg × {(Co−Ch) / W a} (1)
However, Ds = [mass of clay particles having a particle size of 0.075 mm or less in the mixed material (x)] / [mass of solid content of the mixed material (x)] × 100 (%)
Sg = [mass of steelmaking slag particles having a particle diameter of 2 mm or less in the mixture (x)] / [mass of steelmaking slag of the mixture (x)] × 100 (%)
Ch: The mass of slaked lime in 1 m 3 of the mixed material when slaked lime is mixed with the clay to be modified in the prior test and the uniaxial compressive strength after the 28-day curing of the mixed material becomes 50 kN / m 2. (Kg) x 1.5
Co: free CaO contained in steelmaking slag, and the mass of free CaO in 1 m 3 of the mixed material (x) (kg)
Wa: Mass of moisture in mixed material (x) 1 m 3 (kg)
α: 3.6
[2]製鋼スラグを混合して浚渫土の改質を行う方法であって、浚渫土と製鋼スラグの混合材(x)の28日養生後の一軸圧縮強度の目標値をfO(N/cm2)とした場合、下記(2)式に基づき浚渫土に対する製鋼スラグの混合量を決定することを特徴とする浚渫土の改質方法。
fO=α×Ds×Sg×{(Co−Ch)/Wa} …(2)
但し
Ds=[混合材(x)中の粒径0.075mm以下の浚渫土粒子の質量]/[混合材(x)の固形分の質量]×100(%)
Sg=[混合材(x)中の粒径2mm以下の製鋼スラグ粒子の質量]/[混合材(x)の製鋼スラグの質量]×100(%)
Ch:事前の試験において、改質対象である浚渫土に消石灰を混合し、その混合材の28日養生後の一軸圧縮強度が50kN/m2となる場合の混合材1m3中の消石灰の質量(kg)×1.5
Co:製鋼スラグが含有する遊離CaOであって、混合材(x)1m3中の遊離CaOの質量(kg)
Wa:混合材(x)1m3中の水分の質量(kg)
α:3.6
[2] A method of modifying the clay by mixing steelmaking slag, wherein the target value of the uniaxial compressive strength after the 28-day curing of the mixed material (x) of clay and steelmaking slag is set to f O (N / cm 2 ), the mixing method of the clay is determined by determining the amount of steelmaking slag mixed with the clay based on the following formula (2).
f O = α × Ds × Sg × {(Co−Ch) / W a} (2)
However, Ds = [mass of clay particles having a particle size of 0.075 mm or less in the mixed material (x)] / [mass of solid content of the mixed material (x)] × 100 (%)
Sg = [mass of steelmaking slag particles having a particle diameter of 2 mm or less in the mixture (x)] / [mass of steelmaking slag of the mixture (x)] × 100 (%)
Ch: The mass of slaked lime in 1 m 3 of the mixed material when slaked lime is mixed with the clay to be modified in the prior test and the uniaxial compressive strength after the 28-day curing of the mixed material becomes 50 kN / m 2. (Kg) x 1.5
Co: free CaO contained in steelmaking slag, and the mass of free CaO in 1 m 3 of the mixed material (x) (kg)
Wa: Mass of moisture in mixed material (x) 1 m 3 (kg)
α: 3.6
本発明の改質浚渫土の強度推定方法によれば、製鋼スラグを混合して浚渫土の強度改質を行う際に、浚渫土と製鋼スラグの混合材の強度を的確に推定することができ、これにより改質浚渫土の適正な強度設計を実現することができる。
また、本発明の浚渫土の改質方法によれば、製鋼スラグを混合して浚渫土の強度改質を行う際に、設計強度に応じた製鋼スラグの適正な混合量を決定することができ、浚渫土を所望の設計強度に改質することができる。
以上のような本発明法は、従来のように最適条件を求めるための実験を繰り返し行う必要がなく、改質対象となる浚渫土に対して試薬(消石灰)を用いた試験を行うだけでよいため、極めて簡便に実施することができる。
According to the strength estimation method of the modified clay of the present invention, when the strength of the clay is improved by mixing the steelmaking slag, the strength of the mixed material of the clay and the steelmaking slag can be accurately estimated. Thus, an appropriate strength design of the modified clay can be realized.
Further, according to the method for reforming clay according to the present invention, when steelmaking slag is mixed to improve the strength of the clay, an appropriate mixing amount of steelmaking slag according to the design strength can be determined. The clay can be modified to a desired design strength.
The method of the present invention as described above does not require repeated experiments for obtaining optimum conditions as in the prior art, and it is only necessary to perform a test using a reagent (slaked lime) on the clay to be modified. Therefore, it can be implemented very simply.
本発明は、軟弱な浚渫土を海域などで有効利用するために、製鋼スラグに含まれるCaO分を積極的に活用し、浚渫土に製鋼スラグを混合して強度改質を行う技術に関するものである。ここで、浚渫土に混合する製鋼スラグとは、鉄鋼製造プロセスの製鋼工程で発生するスラグであり、例えば、溶銑予備処理スラグ(脱燐スラグ、脱珪スラグ、脱硫スラグなど)、転炉脱炭スラグ、電気炉スラグ、二次精錬スラグなどが挙げられ、これらの1種以上を用いることができる。 TECHNICAL FIELD The present invention relates to a technique for actively using a CaO content contained in steelmaking slag and mixing the steelmaking slag with dredged soil to effectively use soft dredged soil in the sea area. is there. Here, the steelmaking slag mixed with the clay is slag generated in the steelmaking process of the steel production process. For example, hot metal pretreatment slag (dephosphorization slag, desiliconization slag, desulfurization slag, etc.), converter decarburization, etc. Slag, electric furnace slag, secondary refining slag, etc. are mentioned, and one or more of these can be used.
以下、本願の第一の発明である改質浚渫土の強度推定方法について説明する。
この改質浚渫土の強度推定方法は、製鋼スラグを混合して浚渫土の改質を行う際に、浚渫土と製鋼スラグの混合材(x)の強度を推定する方法であり、下記(1)式に基づき、混合材(x)の28日養生後の一軸圧縮強度の推定値f(N/cm 2 )を求めるものである。
f=α×Ds×Sg×{(Co−Ch)/Wa} …(1)
但し
Ds=[混合材(x)中の粒径0.075mm以下の浚渫土粒子の質量]/[混合材(x)の固形分の質量]×100(%)
Sg=[混合材(x)中の粒径2mm以下の製鋼スラグ粒子の質量]/[混合材(x)の製鋼スラグの質量]×100(%)
Ch:事前の試験において、改質対象である浚渫土に消石灰を混合し、その混合材の28日養生後の一軸圧縮強度が50kN/m2となる場合の混合材1m3中の消石灰の質量(kg)×1.5
Co:製鋼スラグが含有する遊離CaOであって、混合材(x)1m3中の遊離CaOの質量(kg)
Wa:混合材(x)1m3中の水分の質量(kg)
α:Chを求めるに当たって使用する消石灰の種類により決まる定数
Hereinafter, the strength estimation method of the modified clay, which is the first invention of the present application, will be described.
The strength estimation method of the modified clay is a method for estimating the strength of the mixed material (x) of the clay and the steelmaking slag when the steelmaking slag is mixed to improve the clay. ) To obtain an estimated value f (N / cm 2 ) of uniaxial compressive strength after 28 days of curing of the mixed material (x).
f = α × Ds × Sg × {(Co−Ch) / W a} (1)
However, Ds = [mass of clay particles having a particle size of 0.075 mm or less in the mixed material (x)] / [mass of solid content of the mixed material (x)] × 100 (%)
Sg = [mass of steelmaking slag particles having a particle diameter of 2 mm or less in the mixture (x)] / [mass of steelmaking slag of the mixture (x)] × 100 (%)
Ch: The mass of slaked lime in 1 m 3 of the mixed material when slaked lime is mixed with the clay to be modified in the prior test and the uniaxial compressive strength after the 28-day curing of the mixed material becomes 50 kN / m 2. (Kg) x 1.5
Co: free CaO contained in steelmaking slag, and the mass of free CaO in 1 m 3 of the mixed material (x) (kg)
Wa: Mass of moisture in mixed material (x) 1 m 3 (kg)
α: Constant determined by the type of slaked lime used to determine Ch
図1は、異なる場所(水域)で採取した浚渫土に種々の添加率で製鋼スラグ(転炉脱炭スラグ,粒径5mm以下,粒径2mm以下のスラグ粒子の割合が15質量%,遊離CaO含有量:9質量%)を加え、この浚渫土と製鋼スラグの混合材について、28日養生後の一軸圧縮強度を調べた結果を示している。これによれば、浚渫土に粒度、組成ともに全く同じ製鋼スラグを添加した場合、或る添加量までは強度が発現しないものの、或る添加量を超えると強度が発現し始め、その後は一次元的に増加することが判った。また、浚渫土の種類によって、強度が発現し始める製鋼スラグの添加量に違いがあることも判った。 FIG. 1 shows that steelmaking slag (converter decarburization slag, particle size of 5 mm or less, slag particle size of 2 mm or less is 15% by mass, free CaO at various addition rates to dredged soil collected in different places (water areas). The content of 9 mass%) is added, and the uniaxial compressive strength after curing for 28 days is shown for the mixed material of this clay and steelmaking slag. According to this, when steelmaking slag having exactly the same particle size and composition is added to the clay, the strength does not develop until a certain addition amount, but the strength starts to appear when a certain addition amount is exceeded, and then one-dimensional. It was found that it increased. It was also found that there is a difference in the amount of steelmaking slag that begins to develop strength depending on the type of clay.
製鋼スラグを浚渫土に添加した場合に、図1に示すように或る添加量までは混合材の強度が発現しないのは、浚渫土にはCa分を吸着する効果があり、このCa吸着が終わった後に強度が発現しはじめるためであると考えられ、これは浚渫土が示す反応抑制効果と言えるものである。本発明者らは、浚渫土がそのような反応抑制効果を示すものであるとの想定の下で、製鋼スラグに代えて消石灰(水酸化カルシウム試薬)を浚渫土に混合し、同様の試験を行った。その結果、それぞれの浚渫土に対して製鋼スラグを添加した場合と類似した挙動を示すことが判った。混合材の強度は余り高くないため、安定した強度とみなせる一軸圧縮強度:50kN/m2が発現した消石灰の添加量と製鋼スラグ(転炉脱炭スラグ,粒径5mm以下,遊離CaO含有量:5質量%)の添加量との相関をとったものを図2に示す。すなわち、図2の各プロットは、ある種類の浚渫土に消石灰、製鋼スラグを別々に添加した際に、一軸圧縮強度:50kN/m2が発現した消石灰の添加量と、製鋼スラグの添加量を示している。
図2によれば、混合材の強度発現の上で、消石灰と製鋼スラグの添加量には極めて強い相関が認められ、製鋼スラグと浚渫土の混合材の強度発現が始まる指標として、消石灰(水酸化カルシウム試薬)を添加したときに強度が発現する最小必要量が重要であると考えられた。
When steelmaking slag is added to the clay, the strength of the mixed material does not develop up to a certain addition amount as shown in FIG. 1, because the clay has an effect of adsorbing Ca, and this Ca adsorption is It is thought that this is because the strength begins to develop after the completion, which can be said to be a reaction suppressing effect exhibited by the clay. Under the assumption that the clay exhibits such a reaction suppressing effect, the present inventors mixed slaked lime (calcium hydroxide reagent) with the clay instead of the steelmaking slag, and conducted the same test. went. As a result, it turned out that the behavior similar to the case where steelmaking slag is added with respect to each clay is shown. Since the strength of the mixed material is not so high, the uniaxial compressive strength that can be regarded as a stable strength: addition amount of slaked lime expressing 50 kN / m 2 and steelmaking slag (converter decarburization slag, particle size of 5 mm or less, free CaO content: FIG. 2 shows a correlation with the addition amount of 5 mass%). That is, each plot of FIG. 2 shows the addition amount of slaked lime with which uniaxial compressive strength: 50 kN / m 2 is expressed and the addition amount of steelmaking slag when slaked lime and steelmaking slag are separately added to a certain type of clay. Show.
According to FIG. 2, a very strong correlation is recognized between the addition amount of slaked lime and steelmaking slag in terms of developing the strength of the mixed material. As an index for starting the strength development of the mixed material of steelmaking slag and clay, slaked lime (water It was considered that the minimum amount required to develop the strength when the calcium oxide reagent) was added was important.
さらに、混合材の強度発現には製鋼スラグ中のCaO成分の影響が大きいと考えられたことから、製鋼スラグのCaO含有量と混合材の関係を調査したが、予想とは異なり、混合材の強度と製鋼スラグのCaO含有量との間にはあまり強い相関は認められなかった。そこで、さらに検討を進めた結果、製鋼スラグ中のCa分のうち、特に反応性の高い遊離CaO量と混合材の強度との相関が高いことが判った。Ca濃度がほぼ一定レベル(35〜40質量%程度)であって、遊離CaO含有量が異なる製鋼スラグ(転炉脱炭スラグ,粒径5mm以下)を浚渫土に一定量(浚渫土:製鋼スラグ=70容積%:30容積%)添加し、この浚渫土と製鋼スラグの混合材について、28日養生後の一軸圧縮強度を調べた結果を図3に示す。図3によれば、製鋼スラグ中の遊離CaO含有量が増加するにしたがって、混合材の強度が増加しており、したがって、この遊離CaO含有量がパラメータとして重要であることが判った。 Furthermore, since it was thought that the influence of the CaO component in steelmaking slag was large in developing the strength of the mixed material, the relationship between the CaO content of the steelmaking slag and the mixed material was investigated. A very strong correlation was not observed between the strength and the CaO content of the steelmaking slag. As a result of further investigations, it was found that, among the Ca components in the steelmaking slag, the correlation between the amount of free CaO that is particularly reactive and the strength of the mixed material is high. Steelmaking slag (converter decarburization slag, particle size 5mm or less) with a free CaO content with a constant Ca concentration (about 35 to 40% by mass) and a certain amount (soil: steelmaking slag) = 70 volume%: 30 volume%), and the results of examining the uniaxial compressive strength after curing for 28 days for the mixed material of the clay and the steelmaking slag are shown in FIG. According to FIG. 3, it was found that as the free CaO content in the steelmaking slag increases, the strength of the mixed material increases, and thus this free CaO content is important as a parameter.
さらに、製鋼スラグの粒度が反応性に強く影響すると考えられることから、その影響を調査した結果、粒径2mm以下のスラグ粒子の比率が混合材の強度に大きな影響を与えることが判った。図4(a),(b)に、2種類の製鋼スラグ(転炉脱炭スラグ,粒径5mm以下)を、粒度を変えた条件で浚渫土(粒径0.075mm以下の浚渫土粒子の割合:約90質量%)と混合した場合におけるスラグ粒度と混合材の強度との関係を示す。図4(a)は、粒径0.075mm以下のスラグ粒子の割合を変えた製鋼スラグを、図4(b)は、粒径2mm以下のスラグ粒子の割合を変えた製鋼スラグを、それぞれ同じ浚渫土に添加し、この浚渫土と製鋼スラグの混合材(浚渫土:製鋼スラグ=70容積%:30容積%)について、28日養生後の一軸圧縮強度を調べたものである。 Furthermore, since it is thought that the particle size of steelmaking slag strongly influences the reactivity, as a result of investigating the influence, it was found that the ratio of slag particles having a particle size of 2 mm or less has a great influence on the strength of the mixed material. 4 (a) and 4 (b), two types of steelmaking slag (converter decarburization slag, particle size of 5 mm or less) were converted into clay (the particle size of 0.075 mm or less of the clay particles under the condition of changing the particle size). The ratio between the slag particle size and the strength of the mixed material is shown. FIG. 4 (a) shows the same steelmaking slag in which the proportion of slag particles having a particle size of 0.075 mm or less is changed, and FIG. 4 (b) shows the same steelmaking slag in which the proportion of slag particles having a particle size of 2 mm or less is changed. The uniaxial compressive strength after curing for 28 days was examined for the mixed material of this clay and steelmaking slag (additional soil: steelmaking slag = 70 vol%: 30 vol%).
図4の結果から以下のような点が判明した。基本的には粒度が細かい製鋼スラグほど反応に寄与すると想定され、粒径0.075mm以下のスラグ粒子の比率でもその傾向は表れているが、強度との相関性という意味では粒径2mm以下のスラグ粒子の比率が極めて相関性が高いことが判った。この理由は必ずしも明らかではないが、大きな粒子は表面積が小さいことから反応活性が乏しくなる一方、細かな粒子ばかりでは大気中のCO2との反応などで反応活性が乏しくなっているものと推定され、適度な粒径が重要であると考えられる。 The following points were found from the results of FIG. Basically, steelmaking slag with a finer particle size is assumed to contribute to the reaction, and this tendency appears even in the ratio of slag particles with a particle size of 0.075 mm or less, but in terms of correlation with strength, the particle size is 2 mm or less. It was found that the ratio of slag particles was highly correlated. The reason for this is not necessarily clear, but it is estimated that large particles have poor reaction activity due to their small surface area, whereas fine particles alone are presumed to have poor reaction activity due to reaction with CO 2 in the atmosphere. It is considered that an appropriate particle size is important.
一方、浚渫によって発生する浚渫土についても、それぞれ特性があり、同じ水域から浚渫した場合でも特性が変動する。この影響について解析した結果、第1に含水比の影響が大きいことが判った。図5は、2種類の製鋼スラグ(転炉脱炭スラグ,粒径5mm以下)を用い、同じ浚渫土と製鋼スラグの組み合わせで含水比のみを変えた混合材(浚渫土:製鋼スラグ=70容積%:30容積%)について、含水比と28日養生後の一軸圧縮強度との関係を調べたものである。図5によれば、含水比が増加するにしたがって混合材の強度が低下しており、含水比と強度との間に明確な相関があることが判った。 On the other hand, dredged soil caused by dredging has its own characteristics, and the characteristics fluctuate even when dredging from the same water area. As a result of analyzing this influence, it was found that the influence of the water content ratio is large. FIG. 5 shows a mixture of two types of steelmaking slag (converter decarburization slag, particle size of 5 mm or less), with the same combination of clay and steelmaking slag, changing only the water content ratio (slag: steelmaking slag = 70 volumes). %: 30% by volume), the relationship between the water content ratio and the uniaxial compressive strength after curing for 28 days was examined. According to FIG. 5, it was found that the strength of the mixed material decreased as the water content ratio increased, and there was a clear correlation between the water content ratio and the strength.
さらに、浚渫土の粒度に着目して解析を進めた結果、粒径0.075mm以下の浚渫土粒子の比率が重要であることが判った。珪砂を加えることで粒径0.075mm以下の粒子の比率を低減させた浚渫土に製鋼スラグ(転炉脱炭スラグ,粒径5mm以下)を添加し、この浚渫土と製鋼スラグの混合材(浚渫土:製鋼スラグ=70容積%:30容積%)について、28日養生後の一軸圧縮強度を調べた。浚渫土中の粒径0.075mm以下の土粒子の比率とその強度との関係を図6に示す。ここで、図6の縦軸は、珪砂を添加する前の浚渫土(粒径0.075μm以下の土粒子の比率:90質量%)の一軸圧縮強度を“1”としたときの強度比を示した。
図6によれば、浚渫土中の粒径0.075mm以下の土粒子の比率に対応して混合材の強度が変化していることが判る。これはコンクリートにおけるペースト部分のように、安定して強度発現をさせるためには、微粒子の比率が重要であることを示している。
Furthermore, as a result of proceeding with the analysis focusing on the grain size of the clay, it was found that the ratio of the clay particles having a particle size of 0.075 mm or less is important. Steelmaking slag (converter decarburization slag, particle diameter of 5 mm or less) is added to the clay whose ratio of particles having a particle diameter of 0.075 mm or less has been reduced by adding silica sand, and a mixture of this clay and steelmaking slag ( The uniaxial compressive strength after curing on the 28th was examined for the clay (steel making slag = 70 vol%: 30 vol%). FIG. 6 shows the relationship between the ratio of the soil particles having a particle size of 0.075 mm or less in the clay and the strength thereof. Here, the vertical axis in FIG. 6 indicates the strength ratio when the uniaxial compressive strength before dredged silica sand (ratio of soil particles having a particle size of 0.075 μm or less: 90 mass%) is “1”. Indicated.
According to FIG. 6, it turns out that the intensity | strength of a mixed material is changing according to the ratio of the soil particle of 0.075 mm or less in the clay. This indicates that the ratio of the fine particles is important in order to stably develop the strength like the paste portion in concrete.
以上の結果から、以下に示すような特定の強度推定式を用いることにより、改質対象の浚渫土に試薬(消石灰)を添加して所定の強度が得られる試薬量を求めるだけで、浚渫土と製鋼スラグの混合材の強度を的確に推定できることが判った。すなわち、事前の試験において、改質対象である浚渫土に消石灰を混合し、その混合材の28日養生後の一軸圧縮強度が50kN/m2となる場合の消石灰の配合量を求めておき、下記(1)式に基づき、混合材(x)の28日養生後の一軸圧縮強度の推定値f(N/cm 2 )を求めるものである。
f=α×Ds×Sg×{(Co−Ch)/Wa} …(1)
但し
Ds=[混合材(x)中の粒径0.075mm以下の浚渫土粒子の質量]/[混合材(x)の固形分の質量]×100(%)
Sg=[混合材(x)中の粒径2mm以下の製鋼スラグ粒子の質量]/[混合材(x)の製鋼スラグの質量]×100(%)
Ch:事前の試験において、改質対象である浚渫土に消石灰を混合し、その混合材の28日養生後の一軸圧縮強度が50kN/m2となる場合の混合材1m3中の消石灰の質量(kg)×1.5
Co:製鋼スラグが含有する遊離CaOであって、混合材(x)1m3中の遊離CaOの質量(kg)
Wa:混合材(x)1m3中の水分の質量(kg)
α:Chを求めるに当たって使用する消石灰の種類により決まる定数
From the above results, by using a specific strength estimation formula as shown below, it is only necessary to add a reagent (slaked lime) to the modification target clay and obtain the amount of reagent that gives a predetermined strength. It was found that the strength of steel and slag mixed material can be estimated accurately. That is, in the preliminary test, slaked lime is mixed with the clay to be modified, and the blended amount of slaked lime when the uniaxial compressive strength after the 28-day curing of the mixed material is 50 kN / m 2 , Based on the following formula (1), the estimated value f (N / cm 2 ) of the uniaxial compressive strength after the 28-day curing of the mixed material (x) is obtained.
f = α × Ds × Sg × {(Co−Ch) / W a} (1)
However, Ds = [mass of clay particles having a particle size of 0.075 mm or less in the mixed material (x)] / [mass of solid content of the mixed material (x)] × 100 (%)
Sg = [mass of steelmaking slag particles having a particle diameter of 2 mm or less in the mixture (x)] / [mass of steelmaking slag of the mixture (x)] × 100 (%)
Ch: The mass of slaked lime in 1 m 3 of the mixed material when slaked lime is mixed with the clay to be modified in the prior test and the uniaxial compressive strength after the 28-day curing of the mixed material becomes 50 kN / m 2. (Kg) x 1.5
Co: free CaO contained in steelmaking slag, and the mass of free CaO in 1 m 3 of the mixed material (x) (kg)
Wa: Mass of moisture in mixed material (x) 1 m 3 (kg)
α: Constant determined by the type of slaked lime used to determine Ch
ここで、浚渫土と製鋼スラグの混合材における強度発現は、セメントにおけるポゾラン反応と同様の機構であり、製鋼スラグから供給されるCaと浚渫土のSi分とが反応して、Ca−Si−H2O化合物を生成することにより強度が発現する。したがって、強度発現にはCa量、Si量、およびセメントなどの反応の場合に強度と逆比例している水量がそれぞれ影響すると考えられる。このような観点と、上述した製鋼スラグや浚渫土の各種特性を組み合わせて解析した結果、上記の強度推定式が見出されたものである。すなわち、Ca量に関与するパラメータとして、製鋼スラグからのCa供給量があり、これには混合材中の粒径2mm以下のスラグ粒子の質量を混合材中の製鋼スラグの質量で除した比率Sgと遊離CaO量Coの寄与がある。一方、浚渫土がCaを吸着することによる反応抑制効果があり、この反応抑制効果は、事前の試験で求められる、混合材の所定の強度が発現するまでの消石灰量が指標となり、したがって、反応に寄与する遊離CaOは(Co−Ch)で表される。また、セメントにおける結合材/水と同様の考え方で、強度発現は(Co−Ch)と混合材に含まれる水分(浚渫土が持ち込んだ海水や水、或いはさらに添加され海水や水)との比(Co−Ch)/Waに大きく依存する。なお、Chについて、「混合材の所定の強度が発現するまでの消石灰の質量×1.5」としたのは、図2に示されるように、強度発現する製鋼スラグの添加率と消石灰の添加率は強い相関があり、消石灰の添加量と製鋼スラグ中の遊離CaO含有率を元に計算した製鋼スラグ中の遊離CaO含有量とを比較すると、製鋼スラグ中の遊離CaO含有量は消石灰の1.5倍相当を要するからである。一方、Si分については、浚渫土のうちの土の量に起因するパラメータは、混合材中の粒径0.075mm以下の浚渫土粒子の比率Dsの寄与がある。これらを掛け合わせることで、強度指標の骨格が求められ、これを一軸圧縮強度に適用させるための定数αを掛けたものが、混合材(x)の一軸圧縮強度の推定値f(N/cm 2 )となる。
ここで、定数αはChを求めるに当たって使用する消石灰の種類(例えば、活性度を左右する粒度及び/又は純度)により決まり、通常は、3〜4程度の範囲で選択される。
Here, the strength expression in the mixed material of the clay and the steelmaking slag is the same mechanism as the pozzolanic reaction in the cement, and Ca supplied from the steelmaking slag reacts with the Si content of the clay and Ca-Si- Strength is developed by generating the H 2 O compound. Accordingly, it is considered that the amount of water that is inversely proportional to the strength in the case of reactions such as Ca amount, Si amount, and cement affects the strength development. As a result of analyzing by combining such viewpoints and various characteristics of the steelmaking slag and clay described above, the above strength estimation formula has been found. That is, as a parameter related to the amount of Ca, there is a Ca supply amount from steelmaking slag, which is a ratio Sg obtained by dividing the mass of slag particles having a particle size of 2 mm or less in the mixed material by the mass of steelmaking slag in the mixed material. And free CaO amount Co. On the other hand, there is a reaction suppression effect due to the adsorption of Ca by the clay, and this reaction suppression effect is an index based on the amount of slaked lime obtained until the predetermined strength of the mixed material is obtained, which is obtained in a prior test. The free CaO that contributes to is represented by (Co-Ch). In addition, the strength development is the ratio between (Co-Ch) and the moisture contained in the mixed material (seawater and water brought in by dredged soil, or seawater and water added further) in the same way as the binder / water in cement. It largely depends on (Co-Ch) / Wa. As for Ch, “mass of slaked lime until a predetermined strength of the mixed material is developed × 1.5” is set as shown in FIG. 2. The rate has a strong correlation. Comparing the added amount of slaked lime with the free CaO content in steelmaking slag calculated based on the free CaO content in steelmaking slag, the free CaO content in steelmaking slag is 1 This is because the equivalent of 5 times is required. On the other hand, with respect to the Si component, the parameter due to the amount of soil in the clay has a contribution of the ratio Ds of clay particles having a particle size of 0.075 mm or less in the mixed material. By multiplying these, the skeleton of the strength index is obtained, and this is multiplied by a constant α for applying to the uniaxial compressive strength, and the estimated value f (N / cm ) of the uniaxial compressive strength of the mixed material (x). 2 ) .
Here, the constant α is determined by the type of slaked lime used for obtaining Ch (for example, the particle size and / or purity that affects the activity), and is usually selected in the range of about 3 to 4.
Chを求めるための事前の試験では、例えば、改質対象とする浚渫土に対して、消石灰の添加量を変更しながら混合し、その圧縮強度を測定することによって、強度の立ち上がり点を求めることが可能である。試験方法は特に限定されるものではないが、JIS−R−5201:1997「セメントの物理試験方法」8.3.1セメントペーストの練混ぜ(1)練混ぜ方法や、地盤工学会『土質試験の方法と解説』第5章 安定処理度の突き固めによる供試体作成の混合方法、に準拠して、数リットルレベルで評価をすれば十分なデータを取ることができる。
従来では、浚渫土と製鋼スラグの混合材の強度が明確に予測できなかったり、或いは実験を繰り返して所望の強度が得られる混合条件を見極める必要があったが、本発明法を適用することにより、改質対象となる浚渫土に対して試薬(消石灰)を用いた事前の試験を行うだけで、混合材の強度を容易に推定することが可能となり、設計条件に適した材料、混合条件を事前に簡便に設定することが可能となる。
In the prior test for obtaining Ch, for example, the rising point of strength is obtained by mixing while changing the amount of slaked lime added to the clay to be modified, and measuring its compressive strength. Is possible. Although the test method is not particularly limited, JIS-R-5201: 1997 “Physical test method of cement” 8.3.1 Mixing of cement paste (1) Kneading method and Geotechnical Society “Soil test Method and explanation ”
In the past, the strength of the mixed material of clay and steelmaking slag could not be clearly predicted, or it was necessary to determine the mixing conditions to obtain the desired strength by repeating the experiment, but by applying the method of the present invention By simply conducting a preliminary test using a reagent (slaked lime) on the clay to be modified, it is possible to easily estimate the strength of the mixed material. It is possible to easily set in advance.
次に、本願の第二の発明である浚渫土の改質方法について説明する。
製鋼スラグを混合して浚渫土の改質を行うに当たり、混合材の目標強度(設計強度)が与えられれば、上記強度推定式により目標強度を得るための製鋼スラグの混合量を求めることができる。
すなわち、本発明の浚渫土の改質方法では、浚渫土と製鋼スラグの混合材(x)の28日養生後の一軸圧縮強度の目標値をfO (N/cm 2 )とした場合、下記(2)式に基づき浚渫土に対する製鋼スラグの混合量を決定する。
fO=α×Ds×Sg×{(Co−Ch)/Wa} …(2)
但し
Ds=[混合材(x)中の粒径0.075mm以下の浚渫土粒子の質量]/[混合材(x)の固形分の質量]×100(%)
Sg=[混合材(x)中の粒径2mm以下の製鋼スラグ粒子の質量]/[混合材(x)の製鋼スラグの質量]×100(%)
Ch:事前の試験において、改質対象である浚渫土に消石灰を混合し、その混合材の28日養生後の一軸圧縮強度が50kN/m2となる場合の混合材1m3中の消石灰の質量(kg)×1.5
Co:製鋼スラグが含有する遊離CaOであって、混合材(x)1m3中の遊離CaOの質量(kg)
Wa:混合材(x)1m3中の水分の質量(kg)
α:Chを求めるに当たって使用する消石灰の種類により決まる定数
Next, a method for reforming clay, which is the second invention of the present application, will be described.
When the steelmaking slag is mixed to improve the clay, if the target strength (design strength) of the mixed material is given, the mixing amount of the steelmaking slag for obtaining the target strength can be obtained by the above strength estimation formula. .
That is, in the modification method of dredged material of the present invention, when the target value of 28 days uniaxial compressive strength after curing of the mixed material and dredged material steel slag (x) was f O (N / cm 2) , the following (2) Based on the formula, determine the amount of steelmaking slag mixed with the clay .
f O = α × Ds × Sg × {(Co−Ch) / W a} (2)
However, Ds = [mass of clay particles having a particle size of 0.075 mm or less in the mixed material (x)] / [mass of solid content of the mixed material (x)] × 100 (%)
Sg = [mass of steelmaking slag particles having a particle diameter of 2 mm or less in the mixture (x)] / [mass of steelmaking slag of the mixture (x)] × 100 (%)
Ch: The mass of slaked lime in 1 m 3 of the mixed material when slaked lime is mixed with the clay to be modified in the prior test and the uniaxial compressive strength after the 28-day curing of the mixed material becomes 50 kN / m 2. (Kg) x 1.5
Co: free CaO contained in steelmaking slag, and the mass of free CaO in 1 m 3 of the mixed material (x) (kg)
Wa: Mass of moisture in mixed material (x) 1 m 3 (kg)
α: Constant determined by the type of slaked lime used to determine Ch
さきに述べたように、本発明の強度推定式により求められる混合材の強度は、実測値との相関が高いため、上記(2)式により目標強度fOに応じた製鋼スラグの混合量を決定することにより、製鋼スラグを目標強度fOに応じた適正な混合量で浚渫材に混合することができる。
浚渫土に所定量の製鋼スラグを混合して強度改質を行う場合、混合方法としては、浚渫された泥土等に対して所定量の製鋼スラグを投入し、混ぜ合わせればよい。混ぜ合わせる方法としては、例えば、バックホーなどの重機を用いて混合する方法、連続式ミキサーに泥土と製鋼スラグを適正比率で投入しながら混合する方法、バッチ式ミキサーに泥土と製鋼スラグを所定量計量して投入して混合する方法などが適用できる。また、混合材の施工方法としては、例えば、混合直後の流動性がある状態でトレミー管などを通して海中に施工する方法、一旦、土運船などに取りおき、少し硬化が始まった状態でバケット投入や底開バージにより施工する方法などが適用できる。また、陸域で使用する場合には、例えば、混合後にトラック等で運搬して施工する方法、泥土発生現地で製鋼スラグを所定量混合し、そのまま養生する方法などが適用できる。
製鋼スラグの混合で改質された浚渫土(混合材)は、主に水域の土工材や盛土材などに好適に利用されるが、陸上の土工材などとしても利用できる。
As described above, since the strength of the mixed material obtained by the strength estimation formula of the present invention has a high correlation with the actual measurement value, the amount of steelmaking slag mixed according to the
When a predetermined amount of steelmaking slag is mixed with dredged soil to improve the strength, the mixing method may be to put a predetermined amount of steelmaking slag into the dredged mud and mix it. As a method of mixing, for example, a method of mixing using a heavy machine such as a backhoe, a method of mixing while putting mud and steelmaking slag in an appropriate ratio into a continuous mixer, and a predetermined amount of mud and steelmaking slag are measured in a batch mixer The method of charging and mixing can be applied. In addition, the construction method of the mixed material is, for example, a method of constructing in the sea through a tremmy pipe etc. in a state where there is fluidity immediately after mixing. And a method of construction by bottom open barge can be applied. In addition, when used in the land, for example, a method of transporting and mixing with a truck after mixing, a method of mixing a predetermined amount of steelmaking slag at the site where mud is generated, and curing as it is can be applied.
The dredged soil (mixed material) modified by mixing steelmaking slag is preferably used mainly as an earthwork material or embankment material in water, but can also be used as an earthwork material on land.
[実施例1]
表1に示す浚渫土A〜Cを改質対象の浚渫土とし、これに添加する製鋼スラグとして表2に示す製鋼スラグa〜cを用いた。なお、一部の浚渫土については、粒度調整のために珪砂を添加した。表3及び表4に示すような組み合わせと混合条件で、浚渫土に対して製鋼スラグを混合し、この混合材の28日養生後の一軸圧縮強度の推定値を本発明法により求めた。本実施例において事前の試験に用いた消石灰は、工業用消石灰特号(JIS−R−9001:2006)であり、(1)式の定数αは3.6とした。また、Chを求めるための事前の試験は、各浚渫土に対して上記消石灰を計量し、モルタルミキサーを用いて混合し、50φ×1100mmのモールドで成形、固化させて実施した。封かん状態で28日養生したサンプルの一軸圧縮強度を測定し、その強度の立ち上がり状況からChを求めた。また、求められた推定値の実測値との相関を確認するために、各混合材の28日封かん養生後の一軸圧縮強度を実測した。それらの結果を表3及び表4に併せて示す。
本発明法で求められた一軸圧縮強度の推定値と、一軸圧縮強度の実測値との相関を図7に示すが、両者の値はよく対応しており、本発明によれば、多様な条件にも関わらず、統括的に圧縮強度を推定することが可能であることが判る。
[Example 1]
The clays A to C shown in Table 1 were used as the modification target clays, and the steelmaking slags a to c shown in Table 2 were used as the steelmaking slag added thereto. For some dredged soils, silica sand was added to adjust the particle size. Steelmaking slag was mixed with the clay under the combinations and mixing conditions as shown in Tables 3 and 4, and the estimated value of the uniaxial compressive strength after 28 days of curing of this mixed material was determined by the method of the present invention. The slaked lime used for the prior test in this example is a special slaked lime for industrial use (JIS-R-9001: 2006), and the constant α in the formula (1) was 3.6. Further, the preliminary test for obtaining Ch was carried out by measuring the slaked lime with respect to each clay, mixing it with a mortar mixer, and molding and solidifying it with a 50φ × 1100 mm mold. The uniaxial compressive strength of the sample cured for 28 days in the sealed state was measured, and Ch was determined from the rise of the strength. Moreover, in order to confirm the correlation with the measured value of the estimated value calculated | required, the uniaxial compressive strength after 28 days sealing curing of each mixed material was measured. The results are also shown in Table 3 and Table 4.
FIG. 7 shows the correlation between the estimated value of the uniaxial compressive strength obtained by the method of the present invention and the measured value of the uniaxial compressive strength. Both values correspond well, and according to the present invention, various conditions are satisfied. Nevertheless, it can be seen that it is possible to estimate the compression strength comprehensively.
[実施例2]
表1に示す浚渫土Aに対して製鋼スラグを混合して強度改質するに当たり、28日養生後の一軸圧縮強度の目標値(平均値)を500kN/m2とした。製鋼スラグとしては、遊離CaO含有量が3.5質量%のものを使用した。使用する製鋼スラグについて、実施時における粒径2mm以下のスラグ粒子の比率を粒度分布測定により評価した上で、(2)式により製鋼スラグの混合量を28質量%と決定した。この混合割合でバッチ式の大型ミキサーにより浚渫土と製鋼スラグを大量混合し、複数個所のサンプルを採取した。混合材の28日養生後の一軸圧縮強度を実測した結果を図8に示す。これによれば、大量製造であるために浚渫土や製鋼スラグの粒度にある程度の変動があり、このため強度にはある程度の幅はあるものの、平均値は506kN/m2である。したがって、本発明の浚渫土の改質方法によれば、設計強度に応じた製鋼スラグの適正な混合量を決定することができ、浚渫土を所望の設計強度に改質することができることが確認できた。
[Example 2]
When the steelmaking slag was mixed with the clay A shown in Table 1 to improve the strength, the target value (average value) of the uniaxial compressive strength after curing for 28 days was set to 500 kN / m 2 . As the steelmaking slag, one having a free CaO content of 3.5% by mass was used. For steel slag to be used, after the ratio of the particle diameter 2mm or less slag particles during implementation assessed by a particle size distribution measurement was determined to 28% by weight mixture of more steelmaking slag (2). At this mixing ratio, a large amount of batch type mixer was used to mix a large amount of clay and steelmaking slag, and samples were taken at a plurality of locations. FIG. 8 shows the results of actual measurement of the uniaxial compressive strength after the 28-day curing of the mixed material. According to this, because of mass production, there is some variation in the grain size of the clay and steelmaking slag, and although there is some range in strength, the average value is 506 kN / m 2 . Therefore, according to the clay reforming method of the present invention, it is possible to determine an appropriate mixing amount of the steelmaking slag according to the design strength, and to confirm that the clay can be modified to a desired design strength. did it.
Claims (2)
下記(1)式に基づき、混合材(x)の28日養生後の一軸圧縮強度の推定値f(N/cm2)を求めることを特徴とする改質浚渫土の強度推定方法。
f=α×Ds×Sg×{(Co−Ch)/Wa} …(1)
但し
Ds=[混合材(x)中の粒径0.075mm以下の浚渫土粒子の質量]/[混合材(x)の固形分の質量]×100(%)
Sg=[混合材(x)中の粒径2mm以下の製鋼スラグ粒子の質量]/[混合材(x)の製鋼スラグの質量]×100(%)
Ch:事前の試験において、改質対象である浚渫土に消石灰を混合し、その混合材の28日養生後の一軸圧縮強度が50kN/m2となる場合の混合材1m3中の消石灰の質量(kg)×1.5
Co:製鋼スラグが含有する遊離CaOであって、混合材(x)1m3中の遊離CaOの質量(kg)
Wa:混合材(x)1m3中の水分の質量(kg)
α:3.6 A method for estimating the strength of a mixed material (x) of clay and steelmaking slag when mixing steelmaking slag and modifying the clay,
A method for estimating the strength of the modified clay characterized by obtaining an estimated value f (N / cm 2 ) of uniaxial compressive strength after 28 days of curing of the mixed material (x) based on the following formula (1).
f = α × Ds × Sg × {(Co−Ch) / W a} (1)
However, Ds = [mass of clay particles having a particle size of 0.075 mm or less in the mixed material (x)] / [mass of solid content of the mixed material (x)] × 100 (%)
Sg = [mass of steelmaking slag particles having a particle diameter of 2 mm or less in the mixture (x)] / [mass of steelmaking slag of the mixture (x)] × 100 (%)
Ch: The mass of slaked lime in 1 m 3 of the mixed material when slaked lime is mixed with the clay to be modified in the prior test and the uniaxial compressive strength after the 28-day curing of the mixed material becomes 50 kN / m 2. (Kg) x 1.5
Co: free CaO contained in steelmaking slag, and the mass of free CaO in 1 m 3 of the mixed material (x) (kg)
Wa: Mass of moisture in mixed material (x) 1 m 3 (kg)
α: 3.6
浚渫土と製鋼スラグの混合材(x)の28日養生後の一軸圧縮強度の目標値をfO(N/cm2)とした場合、下記(2)式に基づき浚渫土に対する製鋼スラグの混合量を決定することを特徴とする浚渫土の改質方法。
fO=α×Ds×Sg×{(Co−Ch)/Wa} …(2)
但し
Ds=[混合材(x)中の粒径0.075mm以下の浚渫土粒子の質量]/[混合材(x)の固形分の質量]×100(%)
Sg=[混合材(x)中の粒径2mm以下の製鋼スラグ粒子の質量]/[混合材(x)の製鋼スラグの質量]×100(%)
Ch:事前の試験において、改質対象である浚渫土に消石灰を混合し、その混合材の28日養生後の一軸圧縮強度が50kN/m2となる場合の混合材1m3中の消石灰の質量(kg)×1.5
Co:製鋼スラグが含有する遊離CaOであって、混合材(x)1m3中の遊離CaOの質量(kg)
Wa:混合材(x)1m3中の水分の質量(kg)
α:3.6 A method of reforming clay by mixing steelmaking slag,
If mixed material dredged material and steel slag 28 days target value of the uniaxial compressive strength after curing of (x) was f O (N / cm 2) , a mixture of steel slag for dredged material on the basis of the following equation (2) A method for reforming dredged soil, wherein the amount is determined.
f O = α × Ds × Sg × {(Co−Ch) / W a} (2)
However, Ds = [mass of clay particles having a particle size of 0.075 mm or less in the mixed material (x)] / [mass of solid content of the mixed material (x)] × 100 (%)
Sg = [mass of steelmaking slag particles having a particle diameter of 2 mm or less in the mixture (x)] / [mass of steelmaking slag of the mixture (x)] × 100 (%)
Ch: The mass of slaked lime in 1 m 3 of the mixed material when slaked lime is mixed with the clay to be modified in the prior test and the uniaxial compressive strength after the 28-day curing of the mixed material becomes 50 kN / m 2. (Kg) x 1.5
Co: free CaO contained in steelmaking slag, and the mass of free CaO in 1 m 3 of the mixed material (x) (kg)
Wa: Mass of moisture in mixed material (x) 1 m 3 (kg)
α: 3.6
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