JP7115886B2 - Method for Predicting Strength Development of Ground Improvement Soil - Google Patents
Method for Predicting Strength Development of Ground Improvement Soil Download PDFInfo
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本発明は、地盤改良土の強度発現性の予測方法に関する。 TECHNICAL FIELD The present invention relates to a method for predicting strength development of ground improvement soil.
減水剤等のセメント混和剤の過剰な添加によって、凝結遅延が起こり、硬化後の目標強度（初期強度）が得られないという問題が生じうることが、知られている（例えば、特許文献１の段落０００３参照）。 It is known that excessive addition of a cement admixture such as a water-reducing agent may cause delay in setting and may cause a problem that the target strength (initial strength) after hardening cannot be obtained (for example, Patent Document 1 See paragraph 0003).
セメント系固化材を用いて軟弱地盤を固化処理して改良するなどの地盤改良工事において、被処理土の強度発現性の調整等を目的として、セメント混和剤（例えば、遅延剤、ＡＥ減水剤等）を用いることがある。
しかし、セメント混和剤の主成分の種類によっては、セメント混和剤を過剰な量で用いると、例えば、材齢２８日の被処理土の一軸圧縮強さが、目標とする値を大きく下回るなどの、強度発現性の問題が生じることがある。
この問題に対処するためには、例えば、被処理土のサンプル、及び、使用予定量のセメント混和剤を用いて、実際に、被処理土の固化処理物を作製し、この固化処理物について、例えば、材齢２８日の被処理土の一軸圧縮強さを測定すれば、強度発現性の良否を確認することができる。
しかし、この場合、強度発現性の良否の確認のために、２８日間を要することになる。
本発明の目的は、セメント系固化材、セメント混和剤、及び水を含む固化材スラリーを用いて、地盤改良工事を行う場合において、地盤改良土（固化処理後の被処理土）の例えば材齢２８日の強度発現性を、簡易にかつ短時間（例えば、３日間）で予測することができる方法を提供することである。
Cement admixtures (e.g., retarders, AE water reducing agents, etc.) are used for the purpose of adjusting the strength development of the treated soil in ground improvement work such as solidifying and improving soft ground using cement-based solidification agents. ) may be used.
However, depending on the type of main component of the cement admixture, if an excessive amount of cement admixture is used, for example, the unconfined compressive strength of the soil to be treated on the 28th day of age may fall far below the target value. , strength development problems may occur.
In order to deal with this problem, for example, using a sample of the soil to be treated and a planned amount of cement admixture to be used, a solidified product of the soil to be treated is actually prepared, and the solidified product is For example, by measuring the unconfined compressive strength of the soil to be treated which is 28 days old, it is possible to confirm the quality of strength development.
However, in this case, it takes 28 days to confirm the quality of strength development.
The object of the present invention is to use a cement-based solidification material, a cement admixture, and a solidification material slurry containing water, when performing ground improvement work, for example, the material age of the ground improvement soil (soil to be treated after solidification treatment) It is an object of the present invention to provide a method capable of easily predicting the intensity development in 28 days in a short period of time (for example, 3 days).
本発明者は、上記課題を解決するために鋭意検討した結果、セメント系固化材、セメント混和剤、及び水を含む固化材スラリーについて、水和反応熱の経時変化を検出可能な熱量計を用いて、所定の材齢における積算発熱量を算出した後、該積算発熱量の値に基いて、上記所定の材齢よりも後の材齢における、固化材スラリーを用いた固化処理後の地盤改良土の強度発現性を予測するという方法によれば、前記の目的を達成しうることを見出し、本発明を完成した。 As a result of intensive studies to solve the above problems, the inventors of the present invention used a calorimeter capable of detecting changes over time in the heat of hydration reaction for a cement-based solidification material, a cement admixture, and a solidification material slurry containing water. After calculating the accumulated calorific value at a predetermined material age, based on the value of the accumulated calorific value, soil improvement after solidification treatment using the solidifying material slurry at a material age later than the predetermined material age The inventors have found that the above object can be achieved by a method of predicting the strength development of soil, and have completed the present invention.
すなわち、本発明は、以下の［１］～［５］を提供するものである。
［１］ セメント系固化材、セメント混和剤、及び水を含む固化材スラリーについて、水和反応熱の経時変化を検出可能な熱量計を用いて、所定の材齢における積算発熱量を算出する積算発熱量算出工程、及び、上記積算発熱量の値に基いて、上記所定の材齢よりも後の材齢における、上記固化材スラリーを用いた固化処理後の地盤改良土の強度発現性を予測する強度発現性予測工程、を含むことを特徴とする地盤改良土の強度発現性の予測方法。
［２］ 上記積算発熱量算出工程における上記所定の材齢が、１～５日であり、かつ、上記強度発現性予測工程における上記所定の材齢よりも後の材齢が、７日以上である、前記［１］に記載の地盤改良土の強度発現性の予測方法。
［３］ 上記セメント混和剤を含まない以外は上記固化材スラリーと同じ材料組成を有する対照用スラリーについて、上記積算発熱量算出工程と同様にして、上記積算発熱量を算出し、得られた値を基準値として定める基準値算出工程を含み、かつ、上記強度発現性予測工程において、上記固化材スラリーについて得られた上記積算発熱量（Ａ）と、上記対照用スラリーについて得られた上記基準値（Ｂ）との比（（Ａ）／（Ｂ）×１００（％））が、予め定めた値以上である場合に、上記強度発現性が良好であると予測する、前記［１］又は［２］に記載の地盤改良土の強度発現性の予測方法。
［４］ 上記比についての上記予め定めた値が、２０～１００％の範囲内で定めた値である、前記［３］に記載の地盤改良土の強度発現性の予測方法。
［５］ 上記セメント混和剤が、オキシカルボン酸系の混和剤、ポリカルボン酸系の混和剤、リグニンスルホン酸系の混和剤、ナフタレンスルホン酸系の混和剤、メラミンスルホン酸系の混和剤、アミノ酸系の混和剤、ポリオール系の混和剤、水溶性高分子系の混和剤、及び、ポリアクリルアミド系の混和剤からなる群より選ばれる一種以上である、前記［１］～［４］のいずれかに記載の地盤改良土の強度発現性の予測方法。
That is, the present invention provides the following [1] to [5].
[1] Integrating to calculate the accumulated calorific value at a predetermined material age using a calorimeter capable of detecting changes in hydration reaction heat over time for a cement-based solidifying material, a cement admixture, and a solidifying material slurry containing water. Based on the calorific value calculation step and the value of the cumulative calorific value, predict the strength development of the ground improvement soil after solidification treatment using the solidification material slurry at a material age later than the predetermined material age. A method for predicting strength development of ground improvement soil, comprising: a strength development prediction step.
[2] The predetermined material age in the cumulative calorific value calculation step is 1 to 5 days, and the material age after the predetermined material age in the strength development prediction step is 7 days or more. The method for predicting strength development of ground improvement soil according to [1] above.
[3] A value obtained by calculating the cumulative calorific value in the same manner as in the step of calculating the cumulative calorific value for a control slurry having the same material composition as the solidifying material slurry except that it does not contain the cement admixture. as a reference value, and in the strength development predicting step, the integrated calorific value (A) obtained for the solidifying material slurry and the reference value obtained for the control slurry The above [1] or [ 2]. The method for predicting the strength development of soil improvement soil described in 2].
[4] The method for predicting strength development of ground improvement soil according to [3] above, wherein the predetermined value for the ratio is a value determined within the range of 20 to 100%.
[5] The cement admixture includes an oxycarboxylic acid-based admixture, a polycarboxylic acid -based admixture, a ligninsulfonic acid-based admixture, a naphthalenesulfonic acid-based admixture, a melamine sulfonic acid-based admixture, and an amino acid. Any one of the above [1] to [4], which is one or more selected from the group consisting of a polyol-based admixture, a polyol-based admixture, a water-soluble polymer-based admixture, and a polyacrylamide-based admixture. The method for predicting strength development of ground improvement soil according to .
本発明によれば、セメント系固化材、セメント混和剤、及び水を含む固化材スラリーを用いて、地盤改良工事を行う場合において、地盤改良土（固化処理後の被処理土）の例えば材齢２８日の強度発現性を、簡易にかつ短時間（例えば、３日間）で予測することができる。 According to the present invention, when performing ground improvement work using a cement-based solidification material, a cement admixture, and a solidification material slurry containing water, the soil improvement soil (soil to be treated after solidification treatment), for example, the material age 28-day intensity development can be predicted easily and in a short period of time (for example, 3 days).
本発明の地盤改良土の強度発現性の予測方法は、（ａ）セメント系固化材（例えば、セメント及び他の有効成分を含むもの）、及び、セメント混和剤（例えば、凝結遅延剤、高性能ＡＥ減水剤等）、及び水を含む固化材スラリーについて、水和反応熱の経時変化を検出可能な熱量計を用いて、所定の材齢（例えば、３日）における積算発熱量を算出する積算発熱量算出工程、及び、（ｂ）上記積算発熱量の値に基いて、上記所定の材齢よりも後の材齢（例えば、７～２８日）における、上記固化材スラリーを用いた固化処理後の地盤改良土の強度発現性を予測する強度発現性予測工程、を含むものである。
以下、工程毎に詳しく説明する。
The method for predicting the strength development of soil improvement soil of the present invention includes (a) a cement-based solidification material (e.g., one containing cement and other active ingredients), and a cement admixture (e.g., setting retarder, high performance AE water reducing agent, etc.) and solidifying material slurry containing water, using a calorimeter capable of detecting the change in the heat of hydration reaction over time, calculate the cumulative calorific value at a predetermined material age (e.g., 3 days) A calorific value calculation step; and (b) a solidification process using the solidifying material slurry at a material age later than the predetermined material age (for example, 7 to 28 days) based on the value of the cumulative calorific value. and a strength development predicting step of predicting the strength development of the subsequent ground improvement soil.
Each step will be described in detail below.
［工程（ａ）：積算発熱量算出工程］
工程（ａ）は、セメント系固化材、及び、セメント混和剤、及び水を含む固化材スラリーについて、水和反応熱の経時変化を検出可能な熱量計を用いて、所定の材齢における積算発熱量を算出する工程である。
セメント系固化材の例としては、セメント及び他の有効成分を含むものや、セメント・石灰複合系固化材等が挙げられる。
ここで、他の有効成分の例としては、高炉スラグ微粉末、石灰石粉末、フライアッシュ、シリカフューム、石膏粉末等が挙げられる。
[Step (a): Cumulative calorific value calculation step]
The step (a) uses a calorimeter capable of detecting changes in the heat of hydration reaction over time for a cement-based solidification material, a cement admixture, and a solidification material slurry containing water, and measures cumulative heat generation at a predetermined material age. This is the step of calculating the amount.
Examples of cement-based solidifying materials include those containing cement and other active ingredients, cement-lime composite-based solidifying materials, and the like.
Here, examples of other active ingredients include granulated blast furnace slag, limestone powder, fly ash, silica fume, gypsum powder, and the like.
セメント混和剤としては、凝結遅延剤、高性能ＡＥ減水剤、高性能減水剤、ＡＥ減水剤、減水剤、流動化剤、増粘剤等が挙げられる。
ここで、凝結遅延剤としては、オキシカルボン酸系凝結遅延剤、リグニンスルホン酸系凝結遅延剤、糖類やセルロース誘導体等の水溶性高分子からなる凝結遅延剤等が挙げられる。
高性能ＡＥ減水剤としては、ポリカルボン酸系高性能ＡＥ減水剤、ナフタリン系高性能ＡＥ減水剤、アミノスルホン酸系高性能ＡＥ減水剤、メラミン系高性能ＡＥ減水剤等が挙げられる。
高性能減水剤としては、ナフタリンスルホン酸系高性能減水剤、メラミンスルホン酸系高性能減水剤、ポリカルボン酸系高性能減水剤等が挙げられる。
Cement admixtures include setting retarders, high-performance AE water-reducing agents, high-performance water-reducing agents, AE water-reducing agents, water-reducing agents, fluidizing agents, thickeners, and the like.
Examples of the setting retarder include oxycarboxylic acid-based setting retarders, ligninsulfonic acid-based setting retarders, and setting retarders composed of water-soluble polymers such as sugars and cellulose derivatives.
Examples of high performance AE water reducing agents include polycarboxylic acid high performance AE water reducing agents, naphthalene high performance AE water reducing agents, aminosulfonic acid high performance AE water reducing agents, and melamine high performance AE water reducing agents.
Examples of the high performance water reducing agent include naphthalenesulfonic acid high performance water reducing agents, melamine sulfonic acid high performance water reducing agents, polycarboxylic acid high performance water reducing agents and the like.
ＡＥ減水剤としては、リグニンスルホン酸系ＡＥ減水剤、オキシカルボン酸系ＡＥ減水剤、ポリオール系ＡＥ減水剤、ポリオキシエチレンアリルエーテル誘導体、アルキルアリルスルホン酸系ＡＥ減水剤等が挙げられる。
減水剤としては、リグニンスルホン酸系ＡＥ減水剤、オキシカルボン酸系ＡＥ減水剤、ポリオール系ＡＥ減水剤、ポリオキシエチレンアリルエーテル誘導体系ＡＥ減水剤、アルキルアリルスルホン酸系ＡＥ減水剤等が挙げられる。
流動化剤としては、ナフタレンスルホン酸系流動化剤、メラミンスルホン酸系流動化剤、ポリカルボン酸系流動化剤、ポリスチレンスルホン酸系流動化剤等が挙げられる。
増粘剤としては、セルロース系増粘剤、ポリアクリルアミド系増粘剤、アミノ酸系増粘剤、バイオポリマー系増粘剤等が挙げられる。
Examples of the AE water reducing agent include ligninsulfonic acid-based AE water reducing agents, oxycarboxylic acid-based AE water reducing agents, polyol-based AE water reducing agents, polyoxyethylene allyl ether derivatives, alkylallyl sulfonic acid-based AE water reducing agents, and the like.
Examples of water reducing agents include ligninsulfonic acid-based AE water reducing agents, oxycarboxylic acid-based AE water reducing agents, polyol-based AE water reducing agents, polyoxyethylene allyl ether derivative-based AE water reducing agents, and alkylarylsulfonic acid-based AE water reducing agents. .
Examples of fluidizing agents include naphthalenesulfonic acid-based fluidizing agents, melaminesulfonic acid-based fluidizing agents, polycarboxylic acid-based fluidizing agents, polystyrenesulfonic acid-based fluidizing agents, and the like.
Examples of thickeners include cellulose-based thickeners, polyacrylamide-based thickeners, amino acid-based thickeners, biopolymer-based thickeners, and the like.
水和反応熱の経時変化を検出可能な熱量計としては、材齢初期のセメント含有スラリーの水和反応熱を測定しうるものであればよく、各種のセメント水和熱測定用の伝導熱量計等が挙げられる。
積算発熱量の算出時の所定の材齢は、地盤改良土の強度発現性の予測の精度を高める観点からは、好ましくは１日以上、より好ましくは２日以上、特に好ましくは３日以上である。
該所定の材齢は、短時間で予測するという本発明の効果の観点からは、好ましくは５日以内、より好ましくは４日以内、特に好ましくは３日以内である。
As a calorimeter that can detect changes in the heat of hydration reaction over time, any calorimeter that can measure the heat of hydration reaction of cement-containing slurry at the early stage of material age can be used. etc.
The predetermined material age at the time of calculating the cumulative calorific value is preferably 1 day or more, more preferably 2 days or more, and particularly preferably 3 days or more, from the viewpoint of increasing the accuracy of prediction of strength development of soil improvement soil. be.
The predetermined material age is preferably within 5 days, more preferably within 4 days, and particularly preferably within 3 days, from the viewpoint of the effect of the present invention that the prediction can be made in a short period of time.
［工程（ｂ）：強度発現性予測工程］
工程（ｂ）は、工程（ａ）で得られた積算発熱量の値に基いて、工程（ａ）における積算発熱量の算出時の材齢（工程（ａ）における所定の材齢）よりも後の材齢（以下、予測対象材齢ともいう。）における、固化材スラリーを用いた固化処理後の地盤改良土の強度発現性を予測する工程である。
ここで、予測対象材齢は、積算発熱量の算出時の材齢（工程（ａ）における所定の材齢）よりも後の材齢における強度発現性を予測しうるという利点を十分に得る観点からは、好ましくは７日以上、より好ましくは１４日以上、さらに好ましくは２１日以上、特に好ましくは２８日以上である。
該予測対象材齢は、強度発現性の予測の必要性の大きさの観点からは、好ましくは９１日以内、より好ましくは５６日以内、特に好ましくは３５日以内である。
[Step (b): Strength Expression Prediction Step]
In step (b), based on the value of the accumulated calorific value obtained in step (a), the material age at the time of calculation of the accumulated calorific value in step (a) (predetermined material age in step (a)) This is a step of predicting the strength development of ground improvement soil after solidification treatment using the solidifying material slurry at a later material age (hereinafter also referred to as a prediction target material age).
Here, the prediction target material age is from the viewpoint of sufficiently obtaining the advantage of being able to predict the strength development at a material age later than the material age at the time of calculating the cumulative calorific value (predetermined material age in step (a)). is preferably 7 days or more, more preferably 14 days or more, still more preferably 21 days or more, and particularly preferably 28 days or more.
The material age to be predicted is preferably 91 days or less, more preferably 56 days or less, and particularly preferably 35 days or less, from the viewpoint of the necessity of strength development prediction.
本発明の好ましい実施形態の一例としては、上述の工程（ａ）～（ｂ）に加えて、（ｃ）セメント混和剤を含まない以外は工程（ａ）の固化材スラリーと同じ材料組成を有する対照用スラリーについて、工程（ａ）（積算発熱量算出工程）と同様にして、積算発熱量を算出し、得られた値を基準値として定める基準値算出工程、を含み、かつ、工程（ｂ）（強度発現性予測工程）において、工程（ａ）の固化材スラリーについて得られた積算発熱量（Ａ）と、工程（ｃ）の対照用スラリーについて得られた上記基準値（Ｂ）との比（（Ａ）／（Ｂ）×１００（％））が、予め定めた値以上である場合に、強度発現性が良好であると予測する方法が挙げられる。
ここで、（Ａ）／（Ｂ）×１００（％）の値は、好ましくは、２０～１００％の範囲内、より好ましくは、２５～８０％の範囲内、さらに好ましくは、３０～６０％の範囲内、特に好ましくは、３５～５０％の範囲内で定めた値である。
該値が２０％以上であれば、良好な強度発現性が得られる確率（本発明の予測の信頼性）を、より高めることができる。該値が１００％以下であれば、良好と評価されるための基準が過度に厳し過ぎず、本発明の方法をより適正に実施することができる。
As an example of a preferred embodiment of the present invention, in addition to the above steps (a) to (b), (c) has the same material composition as the solidifying material slurry of step (a) except that it does not contain a cement admixture For the control slurry, in the same manner as in step (a) (accumulated calorific value calculating step), a reference value calculating step of calculating the accumulated calorific value and determining the obtained value as a reference value, and step (b ) In the (strength expression prediction step), the difference between the integrated calorific value (A) obtained for the solidifying material slurry in step (a) and the reference value (B) obtained for the control slurry in step (c) There is a method of predicting that the strength development is good when the ratio ((A)/(B)×100(%)) is equal to or greater than a predetermined value.
Here, the value of (A) / (B) × 100 (%) is preferably in the range of 20 to 100%, more preferably in the range of 25 to 80%, still more preferably 30 to 60% within the range of, particularly preferably within the range of 35 to 50%.
If the value is 20% or more, the probability of obtaining good strength development (prediction reliability of the present invention) can be further increased. If the value is 100% or less, the criteria for being evaluated as good are not excessively strict, and the method of the present invention can be carried out more properly.
以下、実施例に基いて本発明を説明するが、本発明は実施例に限定されるものではない。
［実験例１～９］
（１）対象土
対象土として、表１に示すものを用いた。
（２）セメント系固化材
セメント系固化材として、特殊土用固化材（太平洋セメント社製、商品名：ジオセット２００）を用いた。この固化材は、セメント、硫酸塩等を含むものである。
（３）セメント混和剤
セメント混和剤として、表２に示すものを用いた。
表２中の「オキシカルボン酸」、「ポリカルボン酸」、「リグニンスルホン酸」は、各々、以下のセメント混和剤を表す。
オキシカルボン酸：地盤改良用のオキシカルボン酸系凝結遅延剤（ＢＡＳＦジャパン社製、商品名：レオソイル３００Ｋ）
ポリカルボン酸：ポリカルボン酸系高性能ＡＥ減水剤（ＢＡＳＦジャパン社製、商品名：マスターグレニウムＳＰ８ＳＶ）
リグニンスルホン酸：リグニンスルホン酸系ＡＥ減水剤（ＢＡＳＦジャパン社製、商品名：ポゾリスＮｏ．７０）
（４）固化材ペーストの調製
表２に示す配合で、セメント系固化材、セメント混和剤、及び純水からなる固化材ペーストを調製した。
EXAMPLES The present invention will be described below based on examples, but the present invention is not limited to the examples.
[Experimental Examples 1 to 9]
(1) Target Soil The soil shown in Table 1 was used as the target soil.
(2) Cement-Based Solidifying Material As a cement-based solidifying material, a special earth-hardening material (manufactured by Taiheiyo Cement Co., Ltd., trade name: GEOSET 200) was used. This solidification material contains cement, sulfate, and the like.
(3) Cement Admixtures As cement admixtures, those shown in Table 2 were used.
"Hydroxycarboxylic acid", "polycarboxylic acid", and "lignosulfonic acid" in Table 2 each represent the following cement admixtures.
Oxycarboxylic acid: oxycarboxylic acid-based setting retarder for ground improvement (manufactured by BASF Japan, trade name: Leosoil 300K)
Polycarboxylic acid: polycarboxylic acid-based high performance AE water reducing agent (manufactured by BASF Japan, trade name: Master Glenium SP8SV)
Ligninsulfonic acid: ligninsulfonic acid-based AE water reducing agent (manufactured by BASF Japan, trade name: Pozzolith No. 70)
(4) Preparation of solidifying material paste A solidifying material paste was prepared according to the formulation shown in Table 2 and composed of a cement-based solidifying material, a cement admixture, and pure water.
（５）積算発熱量の算出
前記（４）で調製した固化材ペーストについて、微小熱量計（東京理工社製、商品名「ＭＭＣ－５１１Ｃ６」）を用いて、材齢３日（７２時間）までの水和発熱速度を測定し、その測定結果に基いて、材齢３日の時点における積算発熱量（Ｊ／時間（ｈｒ））を算出した。測定時の室温は２０℃であった。
（６）材齢２８日の一軸圧縮強さの測定
表２に示すとおり、対象土に対して、対象土１ｍ３当たり３００ｋｇの量のセメント系固化材を、水／セメント系固化材の比が１００質量％であるスラリー（ただし、スラリー中の水の一部を表２に示す割合でセメント混和剤と置換した。）として添加して、ソイルミキサ内にて混合し、混合物を得た。この混合物を用いて、ＪＧＳ－０８２１に規定する「安定処理土の締固めをしない供試体作製方法」に準じて、供試体を作製した。次いで、この供試体を封緘養生（２０℃、７０％相対湿度）して、模擬の地盤改良土を得た。
得られた模擬の地盤改良土について、「ＪＩＳ Ａ １２１６：２００９」（土の一軸圧縮試験方法）に規定されている方法を用いて、材齢２８日の一軸圧縮強さ（ｋＮ／ｍ２）を測定した。
(5) Calculation of accumulated calorific value For the solidifying material paste prepared in (4) above, using a microcalorimeter (manufactured by Tokyo Riko Co., Ltd., trade name "MMC-511C6"), up to 3 days (72 hours) of material age The exothermic rate of hydration was measured, and based on the measurement results, the cumulative calorific value (J/hour (hr)) at the time of 3 days of material age was calculated. The room temperature at the time of measurement was 20°C.
( 6 ) Measurement of unconfined compressive strength on the 28th day of material age It was added as a slurry of 100% by mass (however, part of the water in the slurry was replaced with a cement admixture at the ratio shown in Table 2) and mixed in a soil mixer to obtain a mixture. Using this mixture, a test piece was prepared according to JGS-0821, "Method for preparing test piece without compaction of stabilized soil". Then, this specimen was sealed and cured (20° C., 70% relative humidity) to obtain simulated ground improvement soil.
For the obtained simulated ground improvement soil, using the method specified in "JIS A 1216: 2009" (soil uniaxial compression test method), the uniaxial compression strength (kN/m 2 ) at the age of 28 days was measured.
［対照実験例］
セメント混和剤を用いない以外は実験例１と同様にして、実験した。
以上の結果を表２に示す。
[Example of control experiment]
An experiment was conducted in the same manner as in Experimental Example 1, except that no cement admixture was used.
Table 2 shows the above results.
表２から、以下のことがわかる。
対照実験例における材齢３日の積算発熱量（１７５Ｊ／ｈｒ）を基準値（１００％）とした場合、実験例１、４～７では、材齢３日の積算発熱量が、この基準値（１００％）に対する比で３５％以上であるため、材齢２８日の一軸圧縮強さとして、対照実験例の値（１６１０ｋＮ／ｍ２）を超える値（１６３０～１８７０ｋＮ／ｍ２）を得ている。
一方、実験例２～３、８～９では、材齢３日の積算発熱量が、この基準値（１００％）に対する比で３５％を下回るため、材齢２８日の一軸圧縮強さとして、対照実験例の値（１６１０ｋＮ／ｍ２）よりも小さな値（８９１～１３８０ｋＮ／ｍ２）を得ている。
このことから、材齢３日の積算発熱量が、基準値（１００％）に対する比で３５％以上であるか否かによって、強度発現性の良否（材齢２８日の一軸圧縮強さが大きいか否か）を予測しうることがわかる
Table 2 shows the following.
When the cumulative calorific value (175 J / hr) on the 3rd day of the material age in the control experimental example is set to the reference value (100%), in Experimental Examples 1, 4 to 7, the cumulative calorific value on the 3rd day of the material age is this reference value (100%) is 35% or more, so a value (1630 to 1870 kN/m 2 ) exceeding the value (1610 kN/m 2 ) of the control example was obtained as the unconfined compressive strength at 28 days of material age. there is
On the other hand, in Experimental Examples 2 to 3 and 8 to 9, the accumulated calorific value on the 3rd day of the material age is less than 35% relative to this reference value (100%), so the unconfined compression strength on the 28th day of the material age is A smaller value (891-1380 kN/m 2 ) is obtained than the value (1610 kN/m 2 ) of the control example.
From this, depending on whether the accumulated calorific value at 3 days of material age is 35% or more compared to the reference value (100%), the quality of strength development (unconfined compressive strength at 28 days of material age is large (whether or not) can be predicted
Claims (4)
上記積算発熱量の値に基いて、上記所定の材齢よりも後の材齢における、上記固化材スラリーを用いた固化処理後の地盤改良土の強度発現性を予測する強度発現性予測工程、
を含む地盤改良土の強度発現性の予測方法であって、
上記セメント混和剤を含まない以外は上記固化材スラリーと同じ材料組成を有する対照用スラリーについて、上記積算発熱量算出工程と同様にして、上記積算発熱量を算出し、得られた値を基準値として定める基準値算出工程を含み、かつ、
上記強度発現性予測工程において、上記固化材スラリーについて得られた上記積算発熱量（Ａ）と、上記対照用スラリーについて得られた上記基準値（Ｂ）との比（（Ａ）／（Ｂ）×１００（％））が、予め定めた値以上である場合に、上記強度発現性が良好であると予測することを特徴とする地盤改良土の強度発現性の予測方法。 Cumulative calorific value calculation to calculate the cumulative calorific value at a given material age using a calorimeter capable of detecting changes over time in the heat of hydration reaction of a cementitious solidifying agent, a cement admixture, and a solidifying agent slurry containing water. process, and
A strength development prediction step of predicting the strength development of ground improvement soil after solidification treatment using the solidification material slurry at a material age later than the predetermined material age, based on the value of the cumulative calorific value;
A method for predicting the strength development of soil improvement soil comprising
For a control slurry having the same material composition as the solidifying material slurry except that it does not contain the cement admixture, the cumulative calorific value is calculated in the same manner as the cumulative calorific value calculation step, and the obtained value is the reference value. Including the reference value calculation step specified as, and
In the strength development predicting step, the ratio ((A)/(B)) of the integrated calorific value (A) obtained for the solidifying material slurry and the reference value (B) obtained for the control slurry × 100 (%)) is a predetermined value or more, a method for predicting strength development of ground improvement soil, characterized in that the strength development is predicted to be good .
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