JP7489356B2 - Concrete mix design method - Google Patents

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JP7489356B2
JP7489356B2 JP2021098640A JP2021098640A JP7489356B2 JP 7489356 B2 JP7489356 B2 JP 7489356B2 JP 2021098640 A JP2021098640 A JP 2021098640A JP 2021098640 A JP2021098640 A JP 2021098640A JP 7489356 B2 JP7489356 B2 JP 7489356B2
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孝彦 渡部
均 武田
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Description

本発明は、コンクリートの配合設計方法に関する。 The present invention relates to a method for designing concrete mixes.

骨材の粒度分布がコンクリートの流動性に及ぼす影響は認識されているものの、粒度分布をコンクリートの配合設計に利用する手法が確立されていない。そのため、コンクリートの配合設計を実施する際には、使用する骨材の種類を変更する、複数種類の骨材の混合割合を段階的に変更するなどの配合調整を行って試験練りを繰り返し実施することで、単位水量を最小限に抑えた細骨材率を選定するのが一般的である。
そこで、本発明者等は、非特許文献1に示すように、骨材の粒度分布を変化させた場合のコンクリートの性状を確認することで、粒度分布をJISの粒度分布から大きく変化させた場合でも、コンクリートの基本性能を確保した上で、流動性を改善できることを確認した。
一方、実施工で使用する骨材の粒度は、一般には0.075mm~20mm程度の範囲であり、最適水量を算出することができる手法が求められていた。
Although the effect of aggregate particle size distribution on concrete flowability is recognized, there is no established method to utilize particle size distribution in concrete mix design. Therefore, when designing concrete mix, it is common to select the fine aggregate ratio that minimizes the unit water volume by repeatedly performing test mixing after adjusting the mix, such as changing the type of aggregate used or gradually changing the mixture ratio of multiple types of aggregate.
Therefore, the inventors, as shown in Non-Patent Document 1, confirmed the properties of concrete when the particle size distribution of aggregate was changed, and confirmed that even when the particle size distribution was significantly changed from the JIS particle size distribution, it was possible to improve the fluidity of concrete while maintaining the basic performance of the concrete.
On the other hand, the grain size of the aggregate used in the actual construction is generally in the range of about 0.075 mm to 20 mm, and a method capable of calculating the optimal water volume was required.

渡部孝彦、武田均、橋本理、「細粗骨材の粒度分布を調整したコンクリートの骨材分散距離-流動性の関係性」,土木学会年次学術講演会議概要集(CD-ROM)、74th、V-502、2019年8月1日Takahiko Watanabe, Hitoshi Takeda, Satoshi Hashimoto, "Relationship between aggregate dispersion distance and fluidity of concrete with adjusted particle size distribution of fine and coarse aggregates", Abstracts of the Annual Academic Lecture Conference of the Japan Society of Civil Engineers (CD-ROM), 74th, V-502, August 1, 2019.

本発明は、コンクリートの基本性能の向上を図ることが可能な最適水量を決定するためのコンクリートの配合設計方法を提案することを課題とする。 The objective of this invention is to propose a method for designing concrete mixes to determine the optimal amount of water that can improve the basic performance of concrete.

前記課題を解決するための本発明のコンクリートの配合設計方法は、暫定配合を決定する暫定配合決定工程と、前記暫定配合の骨材分散距離を算出する暫定分散距離算出工程と、前記暫定配合中の骨材の粒度分布を変更して最大骨材分散距離を算出する最大分散距離算出工程と、単位水量と前記最大骨材分散距離との関係式に目標骨材分散距離を当てはめて目標単位水量を算出する目標水量算出工程と、前記目標単位水量を基準として単位水量を変化させた試し練りを行い、最適単位水量を定める最適水量算出工程とを備えている。前記目標骨材分散距離は、「前記暫定配合の骨材分散距離」、もしくは、「スランプと骨材分散距離との関係を表す近似式に予め設定された目標スランプを当てはめて算出したもの」である。
かかるコンクリートの配合設計方法は、従来の方法(これまでに蓄積されたデータや経験則に基づいた方法)により配合されたコンクリートに比べて、単位水量が少ない場合でも必要な流動性を確保し、ひいては、コンクリートの基本性能の向上(乾燥収縮低減、発熱低減)を図ることができる。
The concrete mix design method of the present invention for solving the above problems includes a tentative mix determination step for determining a tentative mix, a tentative dispersion distance calculation step for calculating an aggregate dispersion distance of the tentative mix, a maximum dispersion distance calculation step for calculating a maximum aggregate dispersion distance by changing the particle size distribution of aggregate in the tentative mix, a target water content calculation step for calculating a target unit water content by applying a target aggregate dispersion distance to a relational expression between unit water content and the maximum aggregate dispersion distance, and an optimal water content calculation step for determining an optimal unit water content by performing test mixing in which the unit water content is changed based on the target unit water content. The target aggregate dispersion distance is "the aggregate dispersion distance of the tentative mix" or "calculated by applying a preset target slump to an approximation expression expressing the relationship between slump and aggregate dispersion distance".
Compared to concrete mixed using conventional methods (methods based on accumulated data and empirical rules), this concrete mix design method ensures the necessary fluidity even when the unit water content is small, and ultimately improves the basic performance of the concrete (reduced drying shrinkage and reduced heat generation).

暫定配合のスランプが、目標スランプと同等ではない場合には、前記近似式により算出した前記目標骨材分散距離を利用して、目標単位水量を算出するのが望ましい。
さらに、目標水量算出工程では、y(骨材分散距離)=前記目標骨材分散距離と式2との交点を前記目標単位水量とし、水セメント比を一定とする場合は骨材体積比を式3により算出し、セメント量を一定とする場合は骨材体積比を式4により算出する。
When the slump of the provisional mix is not equal to the target slump, it is desirable to calculate the target unit water content using the target aggregate dispersion distance calculated by the approximation formula .
Furthermore, in the target water volume calculation process, y (aggregate dispersion distance) = the intersection of the target aggregate dispersion distance and Equation 2 is set to the target unit water volume, and when the water-cement ratio is constant, the aggregate volume ratio is calculated using Equation 3, and when the cement amount is constant, the aggregate volume ratio is calculated using Equation 4.

Figure 0007489356000001
Figure 0007489356000001

ここで、骨材分散距離の計算式(式1)における骨材実積率Caには、細粗混合骨材の実績率を使用することが望ましい。しかし、細粗混合骨材の実績率の測定は難しく、試験方法も確立されていない。通常の骨材管理では細骨材と粗骨材それぞれで試験が実施されるのみである。
本発明では、鈴木らの空間率推定手法を補正し、細粗混合骨材の実積率Caを計算する。鈴木らの手法は、空間率εを推定するものであるが、骨材実積率Caは、1-εと等価である。したがって、この空間率の計算値を使用することで、細粗混合骨材の実積率を把握できる。
Here, it is desirable to use the actual aggregate volume ratio C a in the aggregate dispersion distance calculation formula (Formula 1) as the actual aggregate volume ratio of fine and coarse mixed aggregate. However, it is difficult to measure the actual aggregate volume ratio of fine and coarse mixed aggregate, and no test method has been established. In normal aggregate management, tests are only conducted on fine and coarse aggregate separately.
In the present invention, the void ratio estimation method of Suzuki et al. is corrected to calculate the actual volume ratio C a of fine and coarse mixed aggregate. The method of Suzuki et al. estimates the void ratio ε, but the actual volume ratio C a of aggregate is equivalent to 1-ε. Therefore, by using the calculated value of the void ratio, the actual volume ratio of fine and coarse mixed aggregate can be grasped.

本発明のコンクリートの配合設計方法によれば、コンクリートを最適水量により配合することで、当該コンクリートの基本性能の向上を図ることが可能となる。 According to the concrete mix design method of the present invention, by mixing concrete with the optimal amount of water, it is possible to improve the basic performance of the concrete.

本発明の実施形態に係るコンクリートの配合設計方法を示すフローチャートである。1 is a flowchart showing a method for designing a concrete mix according to an embodiment of the present invention. 骨材分散距離の最大値の算出結果の例を示す説明図であって、(a)は2種類の粗骨材を使用し混合割合を調整する場合の粗骨材の混合割合と骨材分散距離の関係を示すグラフ、(b)は細骨材率を調整する場合の細骨材率と骨材分散距離の関係を示すグラフである。FIG. 11 is an explanatory diagram showing an example of the calculation result of the maximum aggregate dispersion distance, where (a) is a graph showing the relationship between the coarse aggregate mixing ratio and the aggregate dispersion distance when two types of coarse aggregate are used and the mixing ratio is adjusted, and (b) is a graph showing the relationship between the fine aggregate rate and the aggregate dispersion distance when the fine aggregate rate is adjusted. 単位水量と最大骨材分散距離との関係式に目標骨材分散距離を当てはめて目標単位水量を算出した場合の単位水量と骨材分散距離との関係を示すグラフの一例である。13 is an example of a graph showing the relationship between unit water content and aggregate dispersion distance when a target unit water content is calculated by applying the target aggregate dispersion distance to a relational equation between unit water content and maximum aggregate dispersion distance. 空間率体積比に重みを考慮することによる効果を確認する検証結果を示すグラフであって、(a)は実施例、(b)は比較例である。11 is a graph showing the results of a verification confirming the effect of considering the weight on the void ratio-to-volume ratio, where (a) is an embodiment and (b) is a comparative example.

本実施形態では、合理的な骨材粒度によるコンクリートの配合設計方法について説明する。本実施形態のコンクリートの配合設計方法では、骨材粒度分布がコンクリートの流動性に影響を及ぼすことに着目し、骨材分離距離の計算手法に対して空間率推定手法を組み合わせることで、一般的に使用されているコンクリートの配合に比べて単位水量を低減できる配合検討を行う。本実施形態のコンクリートの配合設計方法は、図1に示すように、暫定配合決定工程S1、暫定分散距離算出工程S2、最大分散距離算出工程S3、スランプ比較工程S4、目標水量算出工程S5および最適水量算出工程S6を備えている。 In this embodiment, a method for designing a concrete mix with a reasonable aggregate granularity is described. In this embodiment, the concrete mix design method focuses on the effect of aggregate granularity distribution on the fluidity of concrete, and by combining an aggregate separation distance calculation method with a void ratio estimation method, a mix study is carried out that can reduce the unit water content compared to commonly used concrete mixes. As shown in FIG. 1, the concrete mix design method of this embodiment includes a provisional mix determination process S1, a provisional dispersion distance calculation process S2, a maximum dispersion distance calculation process S3, a slump comparison process S4, a target water volume calculation process S5, and an optimal water volume calculation process S6.

暫定配合決定工程S1では、暫定配合を決定する。暫定配合は、例えば、これまでに実績のある調配合、土木学会のコンクリート標準示方書や日本建築学会の建築工事標準仕様書・同解説JASS5鉄筋コンクリート工事などに基づいて作成する。そして、作成された暫定配合により試し練りを行い、スランプ(暫定スランプ)を測定する。なお、工場生産された生コンクリートを購入する等、既知の配合による材料を使用する場合には、既知の配合を暫定配合とする。 In the provisional mix determination step S1, the provisional mix is determined. The provisional mix is prepared based on, for example, proven mixes, the Japan Society of Civil Engineers' Standard Specifications for Concrete, the Architectural Institute of Japan's Standard Specifications for Building Construction and Commentary JASS5 Reinforced Concrete Work, etc. Then, a test mix is performed using the prepared provisional mix, and the slump (provisional slump) is measured. Note that when using materials with a known mix, such as purchasing ready-mix concrete produced in a factory, the known mix is used as the provisional mix.

暫定分散距離算出工程S2では、式1を利用して、暫定配合の骨材分散距離Depを算出する。式1は、余剰ペースト膜厚理論式に基づく骨材分散距離の計算式(Weymouthの式)である。 In the provisional dispersion distance calculation step S2, the aggregate dispersion distance D ep of the provisional mix is calculated using Equation 1. Equation 1 is a calculation formula (Weymouth's formula) for the aggregate dispersion distance based on the theoretical formula for excess paste film thickness.

Figure 0007489356000002
Figure 0007489356000002

なお、体積基準の骨材平均粒径Damは、式5により算出する。 The volume-based average aggregate particle size Dam is calculated using Equation 5.

Figure 0007489356000003
Figure 0007489356000003

また、骨材実積率Caは、「1.0-空間率ε」と等価である。空間率εは式6により算出する。式6は、鈴木らの空間率推定手法(いわゆる鈴木式)による算定式である。 In addition, the aggregate actual volume ratio C a is equivalent to "1.0 - void ratio ε". The void ratio ε is calculated using Equation 6. Equation 6 is a calculation formula based on the void ratio estimation method (the so-called Suzuki formula) proposed by Suzuki et al.

Figure 0007489356000004
Figure 0007489356000004

本実施形態では、鈴木式における粒子に着目した空間率εを式7により算出する。式7では、空間率体積比に重みを考慮している。すなわち、空間率体積比に関する重み係数として、大粒子の間隙に対する小さな粒子の体積(空間率を含む)の割合である第二重み係数w2を式11により算出するとともに、大粒子の空間率のうち未充填の割合である第一重み係数w1を式10により算出し、第一重み係数w1を2粒子の部分的な空間率ε(j,k)に加えることで大粒子に着目した空間率を補正している。 In this embodiment, the void ratio εj focusing on the particles in the Suzuki formula is calculated by Equation 7. In Equation 7, weighting is taken into consideration for the void ratio-volume ratio. That is, as a weighting factor for the void ratio-volume ratio, a second weighting factor w2, which is the ratio of the volume (including void ratio) of small particles to the gaps between large particles, is calculated by Equation 11, and a first weighting factor w1, which is the ratio of the unfilled void ratio of the large particles, is calculated by Equation 10. The first weighting factor w1 is added to the partial void ratio ε(j,k) of the two particles to correct the void ratio focusing on the large particles.

Figure 0007489356000005
Figure 0007489356000005

最大分散距離算出工程S3では、利用可能な骨材の条件の範囲で、暫定配合中の骨材の粒度分布を変更して骨材分散距離を算出し、骨材分散距離が最大となる骨材の使用条件を特定する。利用可能な骨材の条件には、例えば、複数種の細骨材(または粗骨材)の混合率を調整して骨材の粒度分布を調整可能な場合や、使用する細骨材および粗骨材の種類は変更せずに細骨材率を変更して骨材の粒度分布を調整する場合等があり、最大分散距離算出工程では、この与条件を考慮して、骨材分散距離を算出する。このような与条件の例を図2(a)および(b)に示す。図2(a)は、粗骨材容積率Vaと細骨材率s/aを一定とし、細骨材を1種類、粗骨材を2種類使用する条件下での粗骨材混合割合が骨材分散距離に与える影響を示したものである。図2(a)に示すように、2種類の粗骨材G1,G2の混合割合が0.3:0.7のときに、骨材分散距離が最大値の45μmとなった。また、図2(b)は、細骨材および粗骨材がいずれも1種類の場合において、粗骨材容積率Vaが一定である場合の条件下での細骨材率s/aが骨材分散距離に与える影響を示すグラフである。図2(b)に示すように、細骨材率s/aが0.3程度のときに骨材分散率が最大値の30μmとなった。この他の与条件の例としては、例えば、粗骨材容積率Vaおよび細骨材率s/aを一定とし、細骨材を2種類、粗骨材を1種類使用する条件下での細骨材混合割合を変数とした場合や、細骨材を複数種類で混合割合を一定にするとともに粗骨材を複数種類で混合割合を固定して粗骨材容積率Vaを一定として細骨材率を変数とした場合や、単位セメント量を固定し、粗骨材容積率Vaおよび細骨材率s/aを変数とする場合等がある。 In the maximum dispersion distance calculation step S3, the aggregate dispersion distance is calculated by changing the aggregate particle size distribution in the provisional mix within the range of available aggregate conditions, and the aggregate use conditions that maximize the aggregate dispersion distance are identified. Available aggregate conditions include, for example, cases where the aggregate particle size distribution can be adjusted by adjusting the mixing ratio of multiple types of fine aggregate (or coarse aggregate), and cases where the aggregate particle size distribution can be adjusted by changing the fine aggregate ratio without changing the types of fine and coarse aggregate used. In the maximum dispersion distance calculation step, the aggregate dispersion distance is calculated taking these given conditions into consideration. Examples of such given conditions are shown in Figures 2(a) and (b). Figure 2(a) shows the effect of the coarse aggregate mixing ratio on the aggregate dispersion distance under conditions where the coarse aggregate volume ratio Va and the fine aggregate ratio s/a are constant, and one type of fine aggregate and two types of coarse aggregate are used. As shown in Fig. 2(a), when the mixing ratio of two types of coarse aggregate G1, G2 was 0.3:0.7, the aggregate dispersion distance reached a maximum value of 45 μm. Also, Fig. 2(b) is a graph showing the effect of the fine aggregate ratio s/a on the aggregate dispersion distance under the condition that the coarse aggregate volume ratio Va is constant when there is only one type of fine aggregate and one type of coarse aggregate. As shown in Fig. 2(b), when the fine aggregate ratio s/a was about 0.3, the aggregate dispersion ratio reached a maximum value of 30 μm. Examples of other given conditions include, for example, when the coarse aggregate volume ratio Va and fine aggregate ratio s/a are constant and the fine aggregate mixing ratio is a variable under the condition that two types of fine aggregate and one type of coarse aggregate are used, when the mixing ratio is constant for multiple types of fine aggregate and fixed for multiple types of coarse aggregate, the coarse aggregate volume ratio Va is constant and the fine aggregate ratio is a variable, and when the unit cement amount is fixed and the coarse aggregate volume ratio Va and fine aggregate ratio s/a are variables.

スランプ比較工程S4では、暫定配合のスランプである暫定スランプSL1と製造するコンクリートのスランプの目標値である目標スランプSL2とを比較する。暫定スランプSL1と目標スランプSL2とが同等の場合には、目標骨材分散距離Dept=暫定配合の骨材分散距離Dep1とする。一方、暫定スランプSL1と目標スランプSL2とが同等でない場合には、スランプと骨材分散距離との関係を表す近似式(例えば、式12)に、予め設定された目標スランプを当てはめて目標骨材分散距離を算出する。
Dept=Dep1+(SL1-SL2)/0.38 ・・・式12
In the slump comparison step S4, a provisional slump SL1 , which is the slump of the provisional mix, is compared with a target slump SL2, which is the target value of the slump of the concrete to be produced. When the provisional slump SL1 and the target slump SL2 are equivalent, the target aggregate dispersion distance Dept = the aggregate dispersion distance Dep1 of the provisional mix. On the other hand, when the provisional slump SL1 and the target slump SL2 are not equivalent, the target aggregate dispersion distance is calculated by applying a preset target slump to an approximation formula (e.g., formula 12) that expresses the relationship between the slump and the aggregate dispersion distance.
D ept = D ep1 + (SL 1 - SL 2 ) / 0.38 ... formula 12

目標水量算出工程S5では、単位水量と最大骨材分散距離との関係式に目標骨材分散距離を当てはめて目標単位水量を算出する。
目標単位水量は、式2とy=Deptとの交点とする(図3参照)。なお、図3は、単位水量と骨材分散距離との関係を示すグラフの一例である。ここで、水セメント比を一定とする場合は骨材体積比Va(W)を式3により算出し、セメント量を一定とする場合は骨材体積比Va(W)を式4により算出する。
In the target water content calculation step S5, the target aggregate dispersion distance is applied to a relational expression between unit water content and maximum aggregate dispersion distance to calculate a target unit water content.
The target unit water content is the intersection of Equation 2 and y= Dept (see Figure 3). Figure 3 is an example of a graph showing the relationship between unit water content and aggregate dispersion distance. When the water-cement ratio is constant, the aggregate volume ratio V a (W) is calculated using Equation 3, and when the cement content is constant, the aggregate volume ratio V a (W) is calculated using Equation 4.

Figure 0007489356000006
Figure 0007489356000006

最適水量算出工程S6では、目標水量算出工程S5において算出した目標単位水量を基準として単位水量を変化させた試し練りを行い、所要のワーカビリティを確保可能な単位水量である最適単位水量を定める。 In the optimum water amount calculation process S6, test mixing is performed by varying the unit water amount based on the target unit water amount calculated in the target water amount calculation process S5, and the optimum unit water amount that can ensure the required workability is determined.

本実施形態のコンクリートの配合設計方法によれば、細粗混合骨材実積率を算出することで、現状では試験方法が確立されていない細粗混合骨材の実積率測定する必要がない。また、単粒度の実積率を各骨材の粒径判定実積率によって代用することで、現状では試験方法が確立されていない各骨材の単粒度の実積率の測定を省略可能である。
また、使用する骨材に対して新たな骨材試験を行うことなく、JIS A 5005「コンクリート用砕石及び砕砂」で実施を定められている骨材試験(JIS A 1102「骨材のふるい分け試験方法」を含む)の情報のみでコンクリート配合-流動性の評価が可能である。
According to the concrete mix design method of this embodiment, by calculating the actual volume ratio of fine and coarse mixed aggregate, there is no need to measure the actual volume ratio of fine and coarse mixed aggregate, for which no test method has been established at present. In addition, by substituting the actual volume ratio of single grain size with the actual volume ratio determined by the particle size of each aggregate, it is possible to omit measuring the actual volume ratio of single grain size of each aggregate, for which no test method has been established at present.
Furthermore, it is possible to evaluate the concrete mix flowability using only the information from aggregate tests (including JIS A 1102 "Sieving test method for aggregates") required by JIS A 5005 "Crushed stone and crushed sand for concrete" without conducting new aggregate tests on the aggregate used.

以下、本実施形態のコンクリートの配合設計方法について、検証した結果を示す。
本実施形態のコンクリートの配合設計方法(空間率体積比に関する重みを考慮した場合)により骨材分散距離を算出したコンクリートについてスランプを測定した結果を図4(a)に示す。また、比較例として、いわゆる鈴木式(空間率体積比に関する重みを考慮しない場合)を利用して骨材分散距離を算出したコンクリートについてスランプを測定した結果を図4(b)に示す。図4(b)に示すように、スランプと骨材分散距離との関係にばらつきがあったが、図4(a)に示すように、実施例によればスランプと骨材分散距離の関係の相関が向上することが確認できた。
さらに、本実施形態のコンクリートの配合設計方法(空間率体積比に関する重みを考慮した場合)によるコンクリート配合の単位水量の低減効果について検討した。使用材料を表1、配合を表2、試験結果を表3に示す。ここで、比較例は、単位結合材量固定の条件とした。結果、基準配合と比較しスランプは同等で単位水量を8kg/m低減するとともに、圧縮強度およびブリーディング率といったコンクリートの基本性状が向上した配合を作成することができた。
The results of verifying the concrete mix design method of this embodiment are shown below.
Fig. 4(a) shows the results of measuring the slump of concrete in which the aggregate dispersion distance was calculated by the concrete mix design method of this embodiment (in which the weight related to the void ratio-volume ratio was taken into consideration). As a comparative example, Fig. 4(b) shows the results of measuring the slump of concrete in which the aggregate dispersion distance was calculated using the so-called Suzuki formula (in which the weight related to the void ratio-volume ratio was not taken into consideration). As shown in Fig. 4(b), there was variation in the relationship between the slump and the aggregate dispersion distance, but as shown in Fig. 4(a), it was confirmed that the correlation between the slump and the aggregate dispersion distance was improved according to the embodiment.
Furthermore, the effect of reducing the unit water content of concrete mix by the concrete mix design method of this embodiment (when weights related to void volume ratio are considered) was examined. The materials used are shown in Table 1, the mix in Table 2, and the test results in Table 3. Here, the comparative example was set under the condition of a fixed unit binder content. As a result, it was possible to create a mix that had the same slump as the standard mix, reduced the unit water content by 8 kg/ m3 , and improved basic concrete properties such as compressive strength and bleeding rate.

Figure 0007489356000007
Figure 0007489356000007

Figure 0007489356000008
Figure 0007489356000008

Figure 0007489356000009
Figure 0007489356000009

以上、本発明の実施形態について説明したが、本発明は、前述の実施形態に限られず、前記の各構成要素については本発明の趣旨を逸脱しない範囲で適宜変更が可能である。 Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and each of the above-mentioned components can be modified as appropriate without departing from the spirit of the present invention.

S1 暫定配合決定工程
S2 暫定分散距離算出工程
S3 最大分散距離算出工程
S4 スランプ比較工程
S5 目標水量算出工程
S6 最適水量算出工程
S1: Provisional mix determination process; S2: Provisional dispersion distance calculation process; S3: Maximum dispersion distance calculation process; S4: Slump comparison process; S5: Target water volume calculation process; S6: Optimal water volume calculation process

Claims (3)

暫定配合を決定する暫定配合決定工程と、
前記暫定配合の骨材分散距離を算出する暫定分散距離算出工程と、
前記暫定配合中の骨材の粒度分布を変更して最大骨材分散距離を算出する最大分散距離算出工程と、
単位水量と前記最大骨材分散距離との関係式に目標骨材分散距離を当てはめて目標単位水量を算出する目標水量算出工程と、
前記目標単位水量を基準として単位水量を変化させた試し練りを行い、最適単位水量を定める最適水量算出工程と、を備えるコンクリートの配合設計方法であって、
前記目標骨材分散距離は、前記暫定配合の骨材分散距離、もしくは、スランプと骨材分散距離との関係を表す近似式に予め設定された目標スランプを当てはめて算出したものであることを特徴とする、コンクリートの配合設計方法。
A provisional mix determination step for determining a provisional mix;
A provisional dispersion distance calculation step of calculating an aggregate dispersion distance of the provisional mix;
A maximum dispersion distance calculation step of calculating a maximum aggregate dispersion distance by changing the particle size distribution of the aggregate in the provisional mixture;
a target water content calculation step of calculating a target unit water content by applying a target aggregate dispersion distance to a relational expression between unit water content and the maximum aggregate dispersion distance;
A concrete mix design method comprising: a step of performing test mixing in which the unit water amount is changed based on the target unit water amount , and determining an optimal unit water amount;
The method for designing a concrete mix is characterized in that the target aggregate dispersion distance is calculated by applying a preset target slump to an aggregate dispersion distance of the provisional mix or an approximation formula expressing the relationship between slump and aggregate dispersion distance .
前記近似式により算出した前記目標骨材分散距離を利用して、前記目標単位水量を算出することを特徴とする、請求項1に記載のコンクリートの配合設計方法。 2. The method for designing a concrete mix according to claim 1, wherein the target aggregate dispersion distance calculated by the approximation formula is used to calculate the target unit water content. 前記目標水量算出工程において、y=前記目標骨材分散距離と式2との交点を前記目標単位水量とし、
水セメント比を一定とする場合は骨材体積比を式3により算出し、セメント量を一定とする場合は骨材体積比を式4により算出することを特徴とする、請求項1または請求項2に記載のコンクリートの配合設計方法。
Figure 0007489356000010
In the target water content calculation step, y=the intersection point between the target aggregate dispersion distance and Equation 2 is set as the target unit water content;
3. The method for designing a concrete mix according to claim 1, wherein the aggregate volume ratio is calculated by Equation 3 when the water-cement ratio is kept constant, and the aggregate volume ratio is calculated by Equation 4 when the cement amount is kept constant.
Figure 0007489356000010
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