JP2021134301A - Manufacturing method of high strength solidified soil - Google Patents
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- 239000002689 soil Substances 0.000 title claims abstract description 123
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 85
- 239000000463 material Substances 0.000 claims abstract description 53
- 230000018044 dehydration Effects 0.000 claims abstract description 28
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 28
- 238000000034 method Methods 0.000 claims abstract description 14
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 102
- 235000012255 calcium oxide Nutrition 0.000 claims description 51
- 239000000292 calcium oxide Substances 0.000 claims description 51
- 238000012360 testing method Methods 0.000 claims description 23
- 238000013329 compounding Methods 0.000 claims description 15
- 238000006703 hydration reaction Methods 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 9
- 238000009472 formulation Methods 0.000 claims description 7
- 235000008733 Citrus aurantifolia Nutrition 0.000 abstract description 12
- 235000011941 Tilia x europaea Nutrition 0.000 abstract description 12
- 239000004571 lime Substances 0.000 abstract description 12
- 239000004568 cement Substances 0.000 description 29
- 208000005156 Dehydration Diseases 0.000 description 21
- 230000000694 effects Effects 0.000 description 5
- 238000004898 kneading Methods 0.000 description 5
- 238000001035 drying Methods 0.000 description 4
- 238000007711 solidification Methods 0.000 description 4
- 230000008023 solidification Effects 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- 238000012669 compression test Methods 0.000 description 2
- 238000007596 consolidation process Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
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Abstract
Description
本発明は、粘性土に固化材を混合する高強度固化処理土の製造方法に関する。 The present invention relates to a method for producing high-strength solidified soil in which a solidifying material is mixed with cohesive soil.
従来、浚渫土や軟弱粘性土等の粘性土を有効利用する技術として、セメント等の固化材を混合した固化処理土が公知である。一般的な固化処理土の一軸圧縮強さは、0.1MPaから大きくても2〜3MPa程度である。近年では浚渫土の更なる有効利用拡大を目指して、より高強度の固化処理土を得る技術が提案されている。例えば、特許文献１のようにケーキを造立して裏込め材や路盤材として再利用する方法、特許文献２のように脱水ケーキを弱材齢期に再締固めを行い、高強度化、大ブロック化する方法等が挙げられる。 Conventionally, as a technique for effectively utilizing cohesive soil such as dredged soil and soft cohesive soil, solidified soil mixed with a solidifying material such as cement is known. The uniaxial compressive strength of general solidified soil is from 0.1 MPa to at most 2 to 3 MPa. In recent years, a technique for obtaining higher-strength solidified soil has been proposed with the aim of further expanding the effective use of dredged soil. For example, as in Patent Document 1, a method of constructing a cake and reusing it as a backfill material or a roadbed material, and as in Patent Document 2, a dehydrated cake is recompacted at a weak age to increase the strength and increase the strength. Examples include a method of blocking.
上述の技術の高強度化の方向性としては、固化材の添加量を増やすこと、混練水を減らすこと等、すなわち、W/C（水固化材比）を下げることにある。母材となる浚渫土は一般的には高含水比の状態にあり、W/Cを下げるためには脱水工程を必要とする。具体的には浚渫土に固化材を添加混合した後、高圧フィルタープレスにより強制的に圧密排水させる方法がある。しかし、浚渫土の難透水性はよく知られており、圧密排水過程では非常に大きな圧縮圧力と長期の圧密時間を要することから、高コストかつ施工能力の低さが課題となっている。 The direction of increasing the strength of the above-mentioned technique is to increase the amount of the solidifying material added, reduce the kneading water, etc., that is, reduce the W / C (water solidifying material ratio). Dredged soil, which is the base material, is generally in a state of high water content, and a dehydration process is required to reduce W / C. Specifically, there is a method in which a solidifying material is added and mixed with the dredged soil, and then the soil is forcibly consolidated and drained by a high-pressure filter press. However, the poor permeability of dredged soil is well known, and the consolidation drainage process requires a very large compression pressure and a long consolidation time, so high cost and low construction capacity are issues.
その一方で、浚渫土の含水比を天日乾燥等で十分に低下させた上で、固化材を混合するという方法も提案されている（非特許文献１参照）。しかし、浚渫土の含水比が低いと流動性が失われ塑性状を示し、固化材との混練性（ワーカビリティ）が著しく低下し、強度発現を阻害することが懸念される。また、天日乾燥は自然現象に依存するので、浚渫土の含水比をコントロールすることは極めて難しい。 On the other hand, a method has also been proposed in which the water content of the dredged soil is sufficiently lowered by sun-drying or the like, and then the solidifying material is mixed (see Non-Patent Document 1). However, if the water content of the dredged soil is low, the fluidity is lost and it exhibits a plastic state, and the kneadability (workability) with the solidifying material is remarkably lowered, and there is a concern that the strength development may be hindered. Moreover, since sun drying depends on natural phenomena, it is extremely difficult to control the water content of dredged soil.
本発明は、上述のような従来技術の問題に鑑み、高強度固化処理土の製造において実用的な施工性と低コストを実現可能な高強度固化処理土の製造方法を提供することを目的とする。 An object of the present invention is to provide a method for producing high-strength solidified soil, which can realize practical workability and low cost in the production of high-strength solidified soil in view of the above-mentioned problems of the prior art. do.
上記目的を達成するための高強度固化処理土の製造方法は、粘性土に固化材を混合し固化処理土を製造する方法であって、
粘性土を所定の含水比に調整し前記含水比が調整された粘性土を生石灰の添加により脱水した場合の脱水後の含水比を推定する工程と、
前記推定された脱水後の含水比および目標強度に基づいて固化材の添加量を決定する工程と、
前記固化処理土を製造する際に処理対象の粘性土を前記所定の含水比に調整する工程と、
前記含水比調整後の粘性土に前記決定された添加量で前記固化材を添加し混合する工程と、
前記混合された固化処理土に生石灰を添加し混合して化学的に脱水する工程と、を含み、
前記目標強度を高強度に設定し高強度の固化処理土を製造するものである。
The method for producing high-strength solidified soil for achieving the above object is a method for producing solidified soil by mixing a solidifying material with cohesive soil.
A step of adjusting the cohesive soil to a predetermined water content ratio and estimating the water content ratio after dehydration when the cohesive soil having the adjusted water content ratio is dehydrated by adding quicklime.
The step of determining the amount of the solidifying material added based on the estimated water content ratio after dehydration and the target strength, and
A step of adjusting the cohesive soil to be treated to the predetermined water content ratio when producing the solidified soil, and
A step of adding and mixing the solidifying material in the determined addition amount to the cohesive soil after adjusting the water content ratio, and
Includes a step of adding quicklime to the mixed solidified soil, mixing and chemically dehydrating.
The target strength is set to high strength to produce high-strength solidified soil.
この高強度固化処理土の製造方法によれば、まず高含水比状態の粘性土と固化材とを混合するため混練時のワーカビリティーが高く、均一に混合することができるので、固化処理土の品質が向上する。粘性土と固化材の混合後に脱水材として生石灰を添加することにより粘性土の含水比を大幅に低減させることができ、水和反応時の余剰水を脱水することで少ない固化材添加量で固化処理土の高強度化を実現することができる。生石灰の添加混合により化学的に脱水処理を行うので、脱水量のコントロールが可能となる他、高圧脱水機等の特殊な製造機械を必要としないので、製造コストを抑えることができ、低コストを実現できる。また、固化材の水和反応に加えて生石灰のポラゾン反応により長期的に高強度増加が期待できる。また、生石灰による固化膨張で固化材の固化収縮の相殺を期待でき、乾燥収縮ひび割れの低減を図ることができる。 According to this method for producing high-strength solidified soil, first, the cohesive soil in a high water content ratio state and the solidifying material are mixed, so that the workability at the time of kneading is high and the soil can be uniformly mixed. Is improved. By adding fresh lime as a dehydrating material after mixing the cohesive soil and the solidifying material, the water content ratio of the cohesive soil can be significantly reduced, and by dehydrating the excess water during the hydration reaction, it is solidified with a small amount of the solidifying material added. It is possible to increase the strength of the treated soil. Since the dehydration process is chemically performed by adding and mixing quicklime, the amount of dehydration can be controlled, and since a special manufacturing machine such as a high-pressure dehydrator is not required, the manufacturing cost can be suppressed and the cost can be reduced. realizable. Moreover, in addition to the hydration reaction of the solidifying material, a high strength increase can be expected in the long term due to the porazone reaction of quicklime. In addition, the solidification expansion of quicklime can be expected to offset the solidification shrinkage of the solidifying material, and the drying shrinkage cracks can be reduced.
上記高強度固化処理土の製造方法において前記所定の含水比を高含水比に設定し調整することが好ましい。たとえば、前記粘性土の液性限界の1.1〜1.5倍とし、粘性土の含水比を高めに調整することで必要十分な流動性を保った状態で粘性土と固化材とを均一に混合することができる。 In the method for producing high-strength solidified soil, it is preferable to set and adjust the predetermined water content to a high water content. For example, the cohesive soil and the solidifying material should be uniformly mixed while maintaining the necessary and sufficient fluidity by setting the liquidity limit of the cohesive soil to 1.1 to 1.5 times and adjusting the water content ratio of the cohesive soil to a high level. Can be done.
また、前記脱水後の含水比は次式により求めることができる。
w＝(w０-0.77d)/(1+1.32d)
ただし、w：脱水後の含水比、w０：脱水前の含水比、d：生石灰添加率
生石灰添加率d＝生石灰添加量/粘性土の乾燥重量
Further, the water content ratio after dehydration can be calculated by the following formula.
w ＝ (w 0 -0.77d) / (1 + 1.32d)
However, w: water content ratio after dehydration, w 0 : water content ratio before dehydration, d: quicklime addition rate quicklime addition rate d = quicklime addition amount / dry weight of cohesive soil
また、前記固化材添加量の決定工程において前記固化材の添加量を変数とした複数の配合により配合試験を実施し、前記試験結果に基づいて前記固化材の添加量を決定することが好ましい。また、前記生石灰の添加量をも変数とした複数の配合により前記配合試験を実施し、前記試験結果に基づいて前記生石灰の添加量を決定することが好ましい。 Further, in the step of determining the amount of the solidifying material added, it is preferable to carry out a compounding test by using a plurality of formulations with the amount of the solidifying material added as a variable and determine the amount of the solidifying material added based on the test results. Further, it is preferable to carry out the compounding test with a plurality of compounding in which the amount of quicklime added is also a variable, and determine the amount of quicklime added based on the test result.
また、前記配合試験は一軸圧縮強度試験および／またはフロー試験を含む。また、配合計画または前記式による前記固化材の水和反応に寄与しない水量（余裕水）に基づいて前記生石灰添加量の上限値を設定することが好ましい。 The compounding test also includes a uniaxial compressive strength test and / or a flow test. Further, it is preferable to set the upper limit of the amount of quicklime added based on the amount of water (marginal water) that does not contribute to the hydration reaction of the solidifying material according to the compounding plan or the above formula.
また、前記生石灰の添加混合工程の実施時期を前記固化材の凝結開始時間に基づいて設定することが好ましい。 Further, it is preferable to set the execution time of the quicklime addition / mixing step based on the setting start time of the solidifying material.
本発明の高強度固化処理土の製造方法によれば、高強度固化処理土の製造において実用的な施工性と低コストを実現することができる。 According to the method for producing high-strength solidified soil of the present invention, practical workability and low cost can be realized in the production of high-strength solidified soil.
以下、本発明を実施するための形態について図面を用いて説明する。図１は本実施形態による高強度固化処理土の製造方法の各工程を説明するためのフローチャートである。 Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a flowchart for explaining each step of the method for producing high-strength solidified soil according to the present embodiment.
本実施形態による高強度固化処理土の製造方法は、必要十分な流動性を保った状態で粘性土と固化材としてのセメントとを混練した後、脱水材として生石灰を添加混合することで混練水を化学的に脱水することで、高強度固化処理土の製造において実用的な施工性と低コスト化を実現したものである。なお、本実施形態において高強度固化処理土とは、少なくとも9.8MPaの一軸圧縮強度を有する固化処理土をいう。なお、前記設定強度（9.8Mpa）は、準硬石として使用するのに必要な強度であり、海水暴露において求められる非劣化強度である。 In the method for producing high-strength solidified soil according to the present embodiment, cohesive soil and cement as a solidifying material are kneaded while maintaining necessary and sufficient fluidity, and then quicklime is added and mixed as a dehydrating material to knead water. By chemically dehydrating the soil, practical workability and cost reduction are realized in the production of high-strength solidified soil. In this embodiment, the high-strength solidified soil means solidified soil having a uniaxial compressive strength of at least 9.8 MPa. The set strength (9.8Mpa) is the strength required for use as a semi-hard stone, and is the non-deterioration strength required for seawater exposure.
本実施形態による高強度固化処理土の製造方法の各工程Ｓ０１〜Ｓ１０について図１を参照して説明する。まず、現場浚渫時の粘性土の含水比に合わせて粘性土を所定の含水比に調整する（Ｓ０１） Each step S01 to S10 of the method for producing high-strength solidified soil according to this embodiment will be described with reference to FIG. First, the cohesive soil is adjusted to a predetermined water content ratio according to the water content ratio of the cohesive soil at the time of on-site dredging (S01).
粘性土の所定の含水比は、次のように設定し調整する。
・現地で浚渫等により採取された粘性土の自然含水比および液性限界を事前に調べておく。
・現地で浚渫等により採取された粘性土の含水比を液性限界wLの1.1〜1.5倍の含水比に設定し調整する。
The predetermined water content of the cohesive soil is set and adjusted as follows.
・ Investigate the natural water content and liquid limit of cohesive soil collected by dredging on site in advance.
-Adjust the water content of cohesive soil collected locally by dredging, etc. by setting it to 1.1 to 1.5 times the liquid limit wL.
上述のように粘性土の含水比を高めに設定することで、粘性土と固化材との必要十分な混練時の流動性を確保し維持することができる。 By setting the water content ratio of the cohesive soil to be high as described above, it is possible to secure and maintain the necessary and sufficient fluidity of the cohesive soil and the solidifying material at the time of kneading.
次に、含水比が調整された粘性土を生石灰の添加により脱水した場合の生石灰による含水比の低減効果、すなわち、脱水後の含水比を推定する（Ｓ０２）。 Next, when the cohesive soil having an adjusted water content is dehydrated by adding quicklime, the effect of reducing the water content of the quicklime, that is, the water content after dehydration is estimated (S02).
生石灰は、消化吸水反応により見かけの含水比の低減効果だけでなく、化学的な含水比の低減効果がある。上記含水比の粘性土に生石灰を添加し脱水するとした場合の脱水後の含水比は、下記の式（１）による計算で推定する。なお、式（１）は、「石灰による軟弱地盤の安定処理工法」（日本石灰協会）に記載の生石灰による含水比の低減効果式である。
w＝(w０-0.77d)/(1+1.32d) （１）
ただし、w：脱水後の含水比、w０：脱水前の含水比、d：生石灰添加率
生石灰添加率d＝生石灰添加量/粘性土の乾燥重量
Quicklime has not only the effect of reducing the apparent water content ratio due to the digestive water absorption reaction, but also the effect of reducing the chemical water content ratio. When quicklime is added to the cohesive soil having the above water content to dehydrate it, the water content after dehydration is estimated by the calculation by the following formula (1). The formula (1) is a formula for reducing the water content ratio of quicklime described in "Stable treatment method for soft ground with lime" (Japan Lime Association).
w ＝ (w 0 -0.77d) / (1 + 1.32d) (1)
However, w: water content ratio after dehydration, w 0 : water content ratio before dehydration, d: quicklime addition rate quicklime addition rate d = quicklime addition amount / dry weight of cohesive soil
たとえば、粘性土（ρ=2.686g/cm３、wL=75.9%、w０=100%）に生石灰（d=5%）を添加すると、式(１）からｗ＝90.2％となり、約10%の含水比低減効果が得られる。このように、生石灰を用いて化学的に脱水することで、脱水量をコントロールすることができる。 For example, when quicklime (d = 5%) is added to cohesive soil (ρ = 2.686 g / cm 3 , wL = 75.9%, w 0 = 100%), w = 90.2% from equation (1), which is about 10%. The effect of reducing the water content ratio is obtained. In this way, the amount of dehydration can be controlled by chemically dehydrating using quicklime.
次に、脱水後の含水比に対応する水分量がセメント添加による水和反応に供するものと考え、目標の一軸圧縮強度を満たすセメント添加量を暫定的に決定し、その決定された添加量を参考にしてセメント添加量を変数としさらに生石灰添加量を変数として数種類の配合で配合試験を実施する（Ｓ０３）。かかる試験結果に基づいてセメント添加量および生石灰添加量を決定する（Ｓ０４）。 Next, considering that the water content corresponding to the water content ratio after dehydration is used for the hydration reaction by adding cement, the amount of cement added that satisfies the target uniaxial compressive strength is tentatively determined, and the determined addition amount is used. For reference, a compounding test is carried out with several types of formulations, with the amount of cement added as a variable and the amount of quicklime added as a variable (S03). The amount of cement added and the amount of quicklime added are determined based on the test results (S04).
たとえば、固化処理土の一軸圧縮強度は水セメント比（W/C）と高い相関があるので、生石灰による脱水後の水分量（W）からセメント添加量（C）を決定し、セメント添加量および生石灰添加量を変数として各々3〜5水準程度の配合を用意し、目標の一軸圧縮強度およびフロー値に応じた配合検討を行う。なお、生石灰添加量が決まっている場合には、セメント添加量を変数として配合を用意する。 For example, since the uniaxial compressive strength of solidified soil has a high correlation with the water-cement ratio (W / C), the cement addition amount (C) is determined from the water content (W) after dehydration with fresh lime, and the cement addition amount and With the amount of fresh lime added as a variable, prepare a formulation of about 3 to 5 levels each, and study the formulation according to the target uniaxial compressive strength and flow value. If the amount of quicklime added is determined, the amount of cement added is used as a variable to prepare the mixture.
上記配合試験として、たとえば、NEXCO試験方法 試験法 313に基づくフロー試験およびJIS A1216：2009に基づく一軸圧縮試験がある。目標性能の例として、シリンダーフロー値100〜120mm、一軸圧縮強度qu（材齢28日）10MPa以上が挙げられる。配合は、練り混ぜ直後のワーカビリティーや強度を確認しながら決定する。なお、配合試験は、一軸圧縮試験およびフロー試験のいずれか一方でよい場合もある。 As the above-mentioned compounding test, for example, there are a flow test based on the NEXCO test method test method 313 and a uniaxial compression test based on JIS A 1216: 2009. Examples of target performance include a cylinder flow value of 100 to 120 mm and a uniaxial compressive strength of qu (age 28 days) of 10 MPa or more. The composition is determined by checking the workability and strength immediately after kneading. The compounding test may be either a uniaxial compression test or a flow test.
次に、固化処理土を実際に製造する際には処理対象の粘性土を上述のように設定された所定の含水比に調整する（Ｓ０５）。この際に、粘性土の含水比を高めに設定し調整することで、脱水処理は不要でかつ実施の容易な加水調整で済む。 Next, when the solidified soil is actually produced, the cohesive soil to be treated is adjusted to a predetermined water content ratio set as described above (S05). At this time, by setting and adjusting the water content ratio of the cohesive soil to a high value, dehydration treatment is not required and the water content can be easily adjusted.
次に、粘性土に上述のように決定された添加量のセメントを添加し混合する（Ｓ０６）。 Next, the added amount of cement determined as described above is added to the cohesive soil and mixed (S06).
次に、粘性土にセメントが混合された混合材料に上述のように決定された生石灰を添加し混合して脱水する（Ｓ０７）。 Next, quicklime determined as described above is added to the mixed material in which cement is mixed with the cohesive soil, mixed and dehydrated (S07).
上記工程Ｓ０６，Ｓ０７では、粘性土とセメントとを十分に混合攪拌した後で脱水材として生石灰を投入し、再度混合攪拌を行う。これは、流動性が高い状態で粘性土とセメントを均質に混合したうえで、生石灰の脱水効果によりセメント水和反応に不要な余剰水を脱水する考え方に基づくものである。 In the above steps S06 and S07, after sufficiently mixing and stirring the cohesive soil and cement, quicklime is added as a dehydrating material, and the mixing and stirring is performed again. This is based on the idea that cohesive soil and cement are uniformly mixed in a state of high fluidity, and then excess water unnecessary for the cement hydration reaction is dehydrated by the dehydration effect of quicklime.
また、工程Ｓ０６の終了から工程Ｓ０７の開始までの期間、すなわち、脱水材の添加・再混合を実施する時期としては、セメントの凝結初期までに行うのが好ましい。この凝結開始時間については、コンクリートの凝結時間試験方法（JIS 1147）等を参考に決定してもよい。 Further, the period from the end of step S06 to the start of step S07, that is, the time for adding / remixing the dehydrating material is preferably performed by the initial stage of cement setting. The setting start time may be determined with reference to the concrete setting time test method (JIS 1147) or the like.
次に、上述のようにして得られた混合材料を、たとえば、要求される最終形状に対応した型枠に打設し（Ｓ０８）、必要な期間養生し（Ｓ０９）、高強度固化処理土を製造する（Ｓ１０）。上述のようにして、たとえば、水底マウンドに使用する高強度固化処理土からなる石状材料を製造することができる。なお、高強度固化処理土の製造を、条件を変えずに行う場合には、工程Ｓ０５〜Ｓ１０を繰り返す。 Next, the mixed material obtained as described above is cast into a mold corresponding to the required final shape (S08), cured for a required period (S09), and a high-strength solidified soil is prepared. Manufacture (S10). As described above, for example, a stone-like material made of high-strength solidified soil used for a bottom mound can be produced. When the high-strength solidified soil is produced without changing the conditions, steps S05 to S10 are repeated.
本実施形態の高強度固化処理土の製造方法によれば、高含水比状態の粘性土と固化材としてのセメントとを混合するため混練時のワーカビリティーが高く、均一に混合することができるので、固化処理土の品質が向上する。粘性土とセメントの混合後に脱水材として生石灰を添加することにより粘性土の含水比を大幅に低減させることができ、水和反応時の余剰水を脱水することで少ないセメント添加量で固化処理土の高強度化を実現することができる。生石灰の添加混合により化学的に脱水処理を行うので、脱水量のコントロールが可能となる他、高圧脱水機等の特殊な製造機械を必要としないので、製造コストを抑えることができ、低コストを実現できる。また、セメントの水和反応に加えて生石灰のポラゾン反応により長期的に高強度増加が期待できる。また、生石灰による固化膨張でセメントの固化収縮の相殺を期待でき、乾燥収縮ひび割れの低減を図ることができる。 According to the method for producing high-strength solidified soil of the present embodiment, since the cohesive soil in a high water content ratio state and the cement as a solidifying material are mixed, the workability at the time of kneading is high and the soil can be uniformly mixed. The quality of solidified soil is improved. By adding fresh lime as a dehydrating material after mixing cohesive soil and cement, the water content ratio of cohesive soil can be significantly reduced, and by dehydrating excess water during the hydration reaction, solidified treated soil with a small amount of cement added. It is possible to realize high strength. Since the dehydration process is chemically performed by adding and mixing quicklime, the amount of dehydration can be controlled, and since a special manufacturing machine such as a high-pressure dehydrator is not required, the manufacturing cost can be suppressed and the cost can be reduced. realizable. Moreover, in addition to the hydration reaction of cement, a high strength increase can be expected in the long term due to the porazone reaction of quicklime. In addition, the solidification expansion of quicklime can be expected to offset the solidification shrinkage of cement, and the drying shrinkage cracks can be reduced.
次に、本発明の実験例について説明するが、本発明は本実験例に限定されるものではない。図２（ａ）に本実験例に使用した材料の基本情報を示し、図２（ｂ）に図２（ａ）の浚渫土の初期含水比を示し、図２（ｃ）（ｄ）に図２（ａ）の浚渫土を生石灰により脱水した場合の式（１）から算出した脱水後含水比を２ケース示す。図３に本実験例の各配合のデータおよび実験結果を示す。図４に図３の実験例における水セメント比（W/C）と一軸圧縮強度（材齢28日）との関係を示す。 Next, an experimental example of the present invention will be described, but the present invention is not limited to the experimental example. FIG. 2 (a) shows the basic information of the materials used in this experimental example, FIG. 2 (b) shows the initial water content ratio of the dredged soil of FIG. 2 (a), and FIGS. 2 (c) and 2 (d) show. Two cases of the post-dehydrated water content calculated from the formula (1) when the dredged soil of 2 (a) is dehydrated with quicklime are shown. FIG. 3 shows the data and experimental results of each formulation of this experimental example. FIG. 4 shows the relationship between the water-cement ratio (W / C) and the uniaxial compressive strength (material age 28 days) in the experimental example of FIG.
図３の実験例の配合ケースは、生石灰QLの添加率を3.0，5.0，10.0％とし、水セメント比（W/C）をそれぞれ2.32，1.99，1.74としたもので、合計9ケースの配合について図２（ａ）の浚渫土にセメントを混錬してから生石灰を混錬し、養生後に一軸圧縮試験を行い、材齢7日および材齢28日の一軸圧縮強度を測定した。なお、各ケースで３つの試験体（ただし、生石灰添加率5.0％、W/C＝2.32の配合では１つの試験体）で試験を行い、これらの測定結果を図４に示し、それらの平均値を図３に示す。また、図４には生石灰を添加しない比較例についての実験結果も示す。 In the compounding cases of the experimental example in Fig. 3, the addition rates of quicklime QL were 3.0, 5.0, and 10.0%, and the water-cement ratios (W / C) were 2.32, 1.99, and 1.74, respectively. Cement was kneaded into the dredged soil shown in FIG. 2A, and quicklime was kneaded. After curing, a uniaxial compressive test was performed to measure the uniaxial compressive strength at 7 days and 28 days of age. In each case, three test bodies (however, one test body with a quicklime addition rate of 5.0% and W / C = 2.32) were tested, and the measurement results are shown in FIG. 4, and the average value thereof is shown in FIG. Is shown in FIG. In addition, FIG. 4 also shows the experimental results for a comparative example in which quicklime is not added.
図４からW/Cが小さいほど一軸圧縮強度（材齢28日）が大きいことが分かり、また、生石灰添加率が3.0，5.0％では一軸圧縮強度（材齢28日）にさほどの差異はないが、10.0％では一軸圧縮強度（材齢28日）が低いことが分かる。目標の一軸圧縮強度（材齢28日）を、たとえば、12MPaに設定すると、今回の実験例の場合、W/C＝1.9〜2.4、生石灰添加率を3〜7％程度に設定することで目標強度を達成できる。 From Fig. 4, it can be seen that the smaller the W / C, the larger the uniaxial compressive strength (material age 28 days), and when the fresh lime addition rate is 3.0 or 5.0%, there is not much difference in the uniaxial compressive strength (material age 28 days). However, it can be seen that the uniaxial compressive strength (age 28 days) is low at 10.0%. If the target uniaxial compressive strength (age 28 days) is set to, for example, 12 MPa, in the case of this experimental example, the target is set to W / C = 1.9 to 2.4 and the quicklime addition rate to about 3 to 7%. Strength can be achieved.
次に、生石灰（脱水材）の添加率上限値について検討する。図４から分かるように、W/Cが低い（≒浚渫土の含水比が低い）場合、生石灰の添加量が多い（d=10%）と水和反応が十分に行われず、強度が低下する傾向がある。これに対し、(1)浚渫土の塑性限界にあたる水分量は水和反応に供しないこと、(2)セメントの水和反応にはセメント添加量の0.6倍の水分量を必要とすること、(3)生石灰添加量の0.45倍の水分量は蒸発することを配合検討の参考として考慮すると、図３における余裕水が0以下になる場合を、セメントの水和反応が十分でないとし、生石灰添加量の上限値とすることが好ましい。図３の実験例では、生石灰添加率が10.0％でW/C1.99、1.74のケースにおいては余裕水が０以下となっている。なお、余裕水は、セメントの水和反応に寄与しない水量であって、脱水後水分量−（水和反応水＋塑性限界水＋生石灰反応水）から求める。 Next, the upper limit of the addition rate of quicklime (dehydrating material) will be examined. As can be seen from FIG. 4, when the W / C is low (≈ the water content of the dredged soil is low), if the amount of quicklime added is large (d = 10%), the hydration reaction is not sufficiently performed and the strength decreases. Tend. On the other hand, (1) the amount of water that corresponds to the plastic limit of the drowned soil should not be subjected to the hydration reaction, and (2) the hydration reaction of cement requires 0.6 times the amount of water added to the cement. 3) Considering that the water content of 0.45 times the amount of fresh lime added evaporates as a reference for the formulation study, when the margin water in Fig. 3 is 0 or less, it is considered that the hydration reaction of cement is not sufficient and the amount of fresh lime added. It is preferable to set the upper limit value of. In the experimental example of FIG. 3, the quicklime addition rate is 10.0%, and in the cases of W / C 1.99 and 1.74, the surplus water is 0 or less. The marginal water is the amount of water that does not contribute to the hydration reaction of cement, and is obtained from the amount of water after dehydration − (hydration reaction water + plastic limit water + fresh lime reaction water).
以上のように本発明を実施するための形態について説明したが、本発明はこれらに限定されるものではなく、本発明の技術的思想の範囲内で各種の変形が可能である。たとえば、本発明の製造方法により製造された高強度固化処理土は、水底マウンドを構成する捨石のみならず、他の用途にも使用できることはもちろんである。 Although the embodiments for carrying out the present invention have been described above, the present invention is not limited to these, and various modifications can be made within the scope of the technical idea of the present invention. For example, the high-strength solidified soil produced by the production method of the present invention can be used not only for the rubble that constitutes the bottom mound, but also for other purposes.
本発明によれば、高強度固化処理土の製造において実用的な施工性と低コストを実現できるので、高強度固化処理土を効率的に低コストで供給することができ、浚渫土や建設残土等の有効利用を促進できる。 According to the present invention, practical workability and low cost can be realized in the production of high-strength solidified soil, so that high-strength solidified soil can be efficiently supplied at low cost, and dredged soil and construction surplus soil can be supplied. Etc. can be promoted effectively.
Claims (8)
粘性土を所定の含水比に調整し前記含水比が調整された粘性土を生石灰の添加により脱水した場合の脱水後の含水比を推定する工程と、
前記推定された脱水後の含水比および目標強度に基づいて固化材の添加量を決定する工程と、
前記固化処理土を製造する際に処理対象の粘性土を前記所定の含水比に調整する工程と、
前記含水比調整後の粘性土に前記決定された添加量で前記固化材を添加し混合する工程と、
前記混合された固化処理土に生石灰を添加し混合して化学的に脱水する工程と、を含み、
前記目標強度を高強度に設定し高強度の固化処理土を製造する高強度固化処理土の製造方法。 It is a method of producing solidified soil by mixing a solidifying material with cohesive soil.
A step of adjusting the cohesive soil to a predetermined water content ratio and estimating the water content ratio after dehydration when the cohesive soil having the adjusted water content ratio is dehydrated by adding quicklime.
The step of determining the amount of the solidifying material added based on the estimated water content ratio after dehydration and the target strength, and
A step of adjusting the cohesive soil to be treated to the predetermined water content ratio when producing the solidified soil, and
A step of adding and mixing the solidifying material in the determined addition amount to the cohesive soil after adjusting the water content ratio, and
Includes a step of adding quicklime to the mixed solidified soil, mixing and chemically dehydrating.
A method for producing high-strength solidified soil by setting the target strength to high strength and producing high-strength solidified soil.
w＝(w０-0.77d)/(1+1.32d)
ただし、w：脱水後の含水比、w０：脱水前の含水比、d：生石灰添加率
生石灰添加率d＝生石灰添加量/粘性土の乾燥重量 The method for producing high-strength solidified soil according to claim 1 or 2, wherein the water content ratio after dehydration is obtained by the following formula.
w ＝ (w 0 -0.77d) / (1 + 1.32d)
However, w: water content ratio after dehydration, w 0 : water content ratio before dehydration, d: quicklime addition rate quicklime addition rate d = quicklime addition amount / dry weight of cohesive soil
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