JP4211091B2

JP4211091B2 - Concrete production method

Info

Publication number: JP4211091B2
Application number: JP21009698A
Authority: JP
Inventors: 宣典竹田; 茂幸十河
Original assignee: Obayashi Corp
Current assignee: Obayashi Corp
Priority date: 1998-07-24
Filing date: 1998-07-24
Publication date: 2009-01-21
Anticipated expiration: 2018-07-24
Also published as: JP2000037721A

Description

【０００１】
【発明の属する技術分野】
本発明は、主としてドライバッチによるコンクリートの製造方法に関する。
【０００２】
【従来の技術】
コンクリートの製造から運搬までの方法としては、工場で製造されたレディミクストコンクリートをミキサー車に投入し、これを攪拌しながら現場まで搬送する方法と、工場で計量された細骨材、粗骨材及びセメントをミキサー車に投入し、これを攪拌しながら現場まで搬送し、現場に到着後、所定量の水及び混和剤を投入する方法の２つがある。
【０００３】
後者の方法は、いわゆるドライバッチと呼ばれているものであり、ミキサー車に水を投入しないことからスランプ低下や流動性低下の懸念がなく、長距離搬送に適したコンクリートの製造方法といえる。
【０００４】
【発明が解決しようとする課題】
しかしながら、ドライバッチによる方法でも、細骨材が湿潤状態で保管される場合が多いことから、細骨材の表面水率によっては、搬送中においてセメントの一部が細骨材の表面水と反応し凝結を開始してしまうという問題を生じていた。また、その結果として、現場で水や混和剤を投入する際、予定していた量よりも多めの水やＡＥ剤を投入しなければ、設計上のスランプや空気量を確保することができないという事態を招き、コンクリート強度の低下を余儀なくされるという問題も生じていた。
【０００５】
一方、湿潤状態の細骨材を粗骨材やセメントと混合した状態で放置してもスランプを実質的に低下させずに済む限界時間、いわば限界放置時間が存在するが、細骨材の表面水率を３％程度に抑えることができたとしても、限界放置時間は１時間がせいぜいで、ドライバッチ方式を採用する理由がなくなってしまう。そして、そもそもプラントに山積みされた細骨材の表面水率を３％程度に抑えること自体、大変な手間とコストがかかる。
【０００６】
本発明は、上述した事情を考慮してなされたもので、ドライバッチ方式において細骨材の表面水に起因するセメント凝結を回避可能なコンクリートの製造方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
上記目的を達成するため、本発明に係るコンクリートの製造方法は請求項１に記載したように、粗骨材及び表面水率が６％以下の湿潤状態の細骨材からなる骨材の一部を絶乾状態若しくは気乾状態となるように乾燥させ、次いで前記骨材を混合攪拌することにより、前記湿潤状態の細骨材の表面水を前記粗骨材若しくは前記乾燥させた細骨材に吸収させ、しかる後に前記骨材をセメントとともに混合攪拌しつつ搬送し、次いで、水及び必要な混和剤を投入してコンクリートを製造するものである。
また、本発明に係るコンクリートの製造方法は請求項２に記載したように、粗骨材及び湿潤状態の細骨材からなる骨材の一部を絶乾状態若しくは気乾状態となるように乾燥させ、次いで前記骨材を混合攪拌することにより、乾燥させていない細骨材の表面水率を１％〜８％低減させ、しかる後に前記骨材をセメントとともに混合攪拌しつつ搬送し、次いで、水及び必要な混和剤を投入してコンクリートを製造するものである。
【０００８】
また、本発明に係るコンクリートの製造方法は、前記粗骨材を絶乾状態若しくは気乾状態になるように乾燥させ、該粗骨材を前記セメントとの混合攪拌工程の前に前記湿潤状態の細骨材とともに混合攪拌するものである。
【０００９】
また、本発明に係るコンクリートの製造方法は、前記粗骨材に人工軽量骨材を使用するものである。
【００１０】
本発明に係るコンクリートの製造方法においては、まず、粗骨材及び湿潤状態の細骨材からなる骨材の一部を乾燥させ、次いで、かかる骨材を混合攪拌する。
【００１１】
このようにすると、湿潤状態の細骨材の表面水が、乾燥によって吸水能力が生じた細骨材若しくは粗骨材の方に吸収され、結局、当初湿潤状態にあった細骨材は、表乾状態若しくは気乾状態となって表面水をもたない状態となるか、わずかな表面水しか存在しない状態となる。
【００１２】
次に、かかる状態にて骨材をセメントとともに混合攪拌しつつ現場まで搬送し、次いで、現場にて水及び必要な混和剤を投入してコンクリートを製造する。
【００１３】
このとき、細骨材は、表乾若しくは気乾状態となっているかあるいは表面水率がきわめて小さな状態となっているので、セメントとともに混合攪拌しても、セメントと細骨材の表面水との反応は、実質的に生じないか若しくは大幅に抑制される。
【００１４】
骨材を乾燥させる程度は、絶乾状態である必要はなく、わずかでも吸水能力を有する気乾状態で足りるし、粗骨材及び湿潤状態の細骨材からなる骨材のうち、乾燥させる骨材の種類とその量についても任意であって、粗骨材だけ乾燥させる、粗骨材に加えて湿潤状態の細骨材の一部を乾燥させるなどの方法が考えられるが、前記粗骨材を絶乾状態若しくは気乾状態になるように乾燥させ、該粗骨材を前記セメントとの混合攪拌工程の前に前記湿潤状態の細骨材とともに混合攪拌する場合においては、細骨材の表面水が絶乾若しくは気乾状態にある粗骨材に吸収され、湿潤状態にあった細骨材は、表乾若しくは気乾状態となるかあるいは表面水率がきわめて小さい湿潤状態となる。
【００１５】
したがって、かかる状態でセメントと混合攪拌すれば、従来のような細骨材の表面水とセメントとの反応が確実に防止され若しくは大幅に抑制される。なお、この構成では、湿潤状態の細骨材を乾燥させるよりも、より効率的な乾燥が可能となる。
【００１６】
ここで、粗骨材に高吸水骨材若しくは人工軽量骨材を使用するならば、吸水性能が高い分だけ、細骨材の表面水を吸収する能力が大きくなる。したがって、必要な乾燥の程度が緩和されるとともに、使用可能な細骨材の表面水率の上限も緩和される。
【００１７】
【発明の実施の形態】
以下、本発明に係るコンクリートの製造方法の実施の形態について、添付図面を参照して説明する。なお、従来技術と実質的に同一の部品等については同一の符号を付してその説明を省略する。
【００１８】
図１は、本実施形態に係るコンクリートの製造方法の手順を示したフローチャートである。同図でわかるように、本実施形態に係るコンクリートの製造方法においては、まず、粗骨材及び湿潤状態の細骨材からなる骨材のうち、粗骨材を絶乾状態若しくはそれに近くなるまで乾燥炉等を用いて乾燥させる（ステップ１０１）。粗骨材は、できるだけ吸水性の高いものを使用し、できれば高吸水骨材若しくは人工軽量骨材を使用するのが望ましい。
【００１９】
次に、乾燥が終了した粗骨材を湿潤状態の細骨材とともにミキサー車に投入し、これらを混合攪拌する（ステップ１０２）。
【００２０】
このようにすると、湿潤状態の細骨材の表面水が、乾燥によって吸水能力が生じた粗骨材の方に吸収され、結局、当初湿潤状態にあった細骨材は、表乾若しくは気乾状態か、あるいは表面水率がきわめて小さな湿潤状態に変化する。
【００２１】
次に、ミキサー車にセメントを追加投入して粗骨材及び細骨材からなる骨材とともに混合攪拌しつつ現場まで搬送する（ステップ１０３）。このとき、細骨材は、表乾若しくは気乾状態あるいは表面水率のきわめて小さな湿潤状態にあるため、セメントとともに混合攪拌しても、セメントと細骨材の表面水との反応は、実質的に生じないか若しくは大幅に抑制される。
【００２２】
次に、現場にて水及び必要な混和剤をミキサー車に投入してコンクリートを製造する（ステップ１０４）。なお、この段階で粗骨材及び細骨材が気乾状態になっておれば、示方配合に合うように適宜水量補正を行う。
【００２３】
以上説明したように、本実施形態に係るコンクリートの製造方法によれば、粗骨材を絶乾状態若しくはそれに近い状態に乾燥させ、該粗骨材を湿潤状態にある細骨材とともに攪拌混合し、しかる後にセメントとともに混合攪拌しながら現場まで搬送するようにしたので、細骨材は、その表面水が粗骨材に吸収されて表乾若しくは気乾状態あるいは表面水率がきわめて小さな湿潤状態となる。
【００２４】
したがって、このような粗骨材及び細骨材をセメントとともに混合攪拌しながら現場まで長時間搬送しても、セメントと細骨材の表面水との反応を実質的になくすか、あるいは大幅に抑制することが可能となり、限界放置時間（スランプを実質的に減少させずに済む限界時間）を大幅に延ばすことができる。例えば、細骨材の表面水率を１％以下に調整できたとすると、限界放置時間は、約３時間になる。
【００２５】
ちなみに、従来においては、細骨材の表面水率が３％以上になると、限界放置時間は１時間となり、ドライバッチ方式の利点である長距離搬送はほとんど不可能であった。また、細骨材の表面水率が３％の場合に３時間放置すると、コンクリート圧縮強度が２０％低下し、表面水率が６％の場合に６時間放置すると、コンクリート圧縮強度が５０％低下する。
【００２６】
一方、本実施形態に係るコンクリートの製造方法によれば、湿潤状態の細骨材を表面水率がきわめて小さな状態に変化させて限界放置時間を延ばすことができるので、遠方の現場であっても示方配合通りの水やＡＥ剤で設計通りのスランプ、空気量及びコンクリート強度を確保することが可能となる。
【００２７】
また、本実施形態に係るコンクリートの製造方法によれば、粗骨材及び湿潤状態の細骨材からなる骨材のうち、粗骨材を乾燥させるようにしたので、湿潤状態の細骨材の一部を乾燥させるよりも、乾燥効率の向上を図ることが可能となる。
【００２８】
また、本実施形態に係るコンクリートの製造方法によれば、粗骨材に高吸水骨材若しくは人工軽量骨材を使用するようにしたので、吸水性能が高い分だけ、細骨材の表面水を吸収する能力が大きくなる。したがって、必要な乾燥の程度が緩和されて乾燥工程の負担が軽くなるとともに、使用可能な細骨材の表面水率の上限も例えば５％から６％に緩和される。
【００２９】
ここで、３つのコンクリート配合例（いずれもスランプ８ｃｍ）を表１に示すとともに、各配合で使用する３種類の粗骨材の吸水可能量とその吸水可能量を細骨材の表面水率に換算した値とを表２に示す。
【００３０】
【表１】

【００３１】
【表２】

【００３２】
表２から、表１に示した配合例では、標準的な骨材、高吸収骨材、人工軽量骨材の３種類の粗骨材を絶乾状態まで乾燥させた場合、それぞれ約１％、３％、８％の表面水率に相当する細骨材の表面水を吸収する（言い換えれば、表面水率をそれぞれ約１％、３％、８％低減させる）ことが可能であることがわかる。
【００３３】
本実施形態では、粗骨材及び湿潤状態の細骨材からなる骨材の一部を乾燥させるようにしたが、骨材すべてを乾燥させるようにしても、セメントを追加投入して混合攪拌したときのセメントの凝結を防止することができることは言うまでもない。なお、かかる構成においては、骨材同士の混合攪拌工程を省略することが可能となる。
【００３４】
【発明の効果】
以上述べたように、請求項１及び２に係る本発明のコンクリートの製造方法によれば、湿潤状態にあった細骨材は、表乾若しくは気乾状態となるかあるいは表面水率がきわめて小さい湿潤状態となる。したがって、このような粗骨材及び細骨材をセメントとともに混合攪拌しながら現場まで長時間搬送しても、セメントと細骨材の表面水との反応を実質的になくすか、あるいは大幅に抑制することが可能となり、限界放置時間を大幅に延ばすことができるとともに、その結果、遠方の現場であっても示方配合通りの水やＡＥ剤で設計通りのスランプ、空気量及びコンクリート強度を確保することが可能となる。
【００３５】
また、請求項３に係る本発明のコンクリートの製造方法によれば、湿潤状態の細骨材の一部を乾燥させるよりも、乾燥効率の向上を図ることが可能となるという効果も奏する。
【００３６】
また、請求項４に係る本発明のコンクリートの製造方法によれば、吸水性能が高い分だけ、細骨材の表面水を吸収する能力が大きくなり、必要な乾燥の程度が緩和されるとともに、使用可能な細骨材の表面水率の上限も緩和されるという効果も奏する。
【００３７】
【図面の簡単な説明】
【図１】本実施形態に係るコンクリートの製造方法の手順を示したフローチャート。[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a method for producing concrete by dry stitch.
[0002]
[Prior art]
As a method from concrete production to transportation, ready mixed concrete manufactured in a factory is put into a mixer truck and transported to the site while stirring, and fine aggregate and coarse aggregate measured in the factory. In addition, there are two methods: putting cement into a mixer truck, transporting it to the site while stirring, and feeding a predetermined amount of water and admixture after arrival at the site.
[0003]
The latter method is called a so-called dry-tatch, and since it does not throw water into the mixer truck, there is no concern about slump reduction or fluidity reduction, and it can be said to be a concrete manufacturing method suitable for long-distance conveyance.
[0004]
[Problems to be solved by the invention]
However, since dry aggregates are often stored in a wet state even with the dry-dry method, some of the cement reacts with the surface water of the fine aggregates during transportation depending on the surface water ratio of the fine aggregates. However, there was a problem that the condensation started. In addition, as a result, when water and admixtures are introduced at the site, it is not possible to secure a slump and air volume for design unless more water and AE agents are introduced than planned. There was also a problem that the situation caused the concrete strength to be lowered.
[0005]
On the other hand, there is a limit time, that is, a limit neglect time that does not substantially reduce the slump even when the wet fine aggregate is left mixed with coarse aggregate or cement. Even if the water rate can be suppressed to about 3%, the limit leaving time is 1 hour at most, and there is no reason to adopt the dry-chatch method. In the first place, suppressing the surface water ratio of the fine aggregates piled up in the plant to about 3% itself is very laborious and costly.
[0006]
The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a concrete manufacturing method capable of avoiding cement condensation due to surface water of fine aggregates in the dry-datch method.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a concrete production method according to the present invention is a part of an aggregate comprising a coarse aggregate and a fine aggregate in a wet state with a surface water content of 6% or less as described in claim 1. Is dried in an absolutely dry state or an air-dried state, and then the aggregate is mixed and stirred, so that the surface water of the wet fine aggregate is applied to the coarse aggregate or the dried fine aggregate. Then, the aggregate is conveyed while being mixed and stirred together with cement, and then concrete is produced by adding water and a necessary admixture.
Further, according to the method for producing concrete according to the present invention, a part of the aggregate composed of coarse aggregate and wet fine aggregate is dried so as to be in an absolutely dry state or an air dry state. Then, by mixing and stirring the aggregate, the surface water content of the fine aggregate that has not been dried is reduced by 1% to 8%, and then the aggregate is transported with mixing and stirring together with the cement. Concrete is produced by adding water and necessary admixtures.
[0008]
Further, the method for producing concrete according to the present invention, the coarse aggregate is dried so as to be in an absolutely dry state or an air dry state, and the coarse aggregate is in the wet state before the mixing and stirring step with the cement. Mixing and stirring together with fine aggregate.
[0009]
A method of manufacturing a concrete according to the present invention is to use the artificial lightweight aggregate to the coarse aggregate.
[0010]
In the method for producing concrete according to the present invention, first, a part of aggregate composed of coarse aggregate and wet fine aggregate is dried, and then the aggregate is mixed and stirred.
[0011]
In this way, the surface water of the fine aggregate in the wet state is absorbed by the fine aggregate or coarse aggregate that has absorbed water by drying, and as a result, the fine aggregate that was initially in the wet state is the surface. It will be in a dry state or an air-dry state and will have no surface water, or it will be in a state where there is little surface water.
[0012]
Next, in this state, the aggregate is transported to the site while being mixed and stirred together with the cement, and then concrete is produced by adding water and a necessary admixture at the site.
[0013]
At this time, since the fine aggregate is in a surface dry or air dry state or a surface water ratio is extremely small, even if it is mixed and stirred together with the cement, the surface water of the cement and the fine aggregate is not mixed. The reaction does not occur substantially or is greatly suppressed.
[0014]
The degree of drying of the aggregate does not need to be in an absolutely dry state, it is sufficient to have an air-drying state having a water absorption capacity, and among the aggregates composed of coarse aggregate and fine aggregate in wet state, the bone to be dried is sufficient. The type and amount of the material are also arbitrary, and methods such as drying only the coarse aggregate, or drying a part of the wet fine aggregate in addition to the coarse aggregate are conceivable. In the case where the coarse aggregate is mixed and stirred together with the wet fine aggregate before the mixing and stirring step with the cement, the surface of the fine aggregate is dried. Water is absorbed by the coarse aggregate in an absolutely dry or air-dried state, and the fine aggregate that has been in a wet state becomes a surface-dried or air-dried state or a wet state with an extremely small surface water content.
[0015]
Therefore, if the mixture is stirred with cement in such a state, the reaction between the surface water of the fine aggregate and the cement as in the prior art is reliably prevented or significantly suppressed. In this configuration, it is possible to dry more efficiently than to dry the wet fine aggregate.
[0016]
Here, if a highly water-absorbing aggregate or an artificial lightweight aggregate is used as the coarse aggregate, the ability to absorb the surface water of the fine aggregate increases as the water absorption performance is higher. Accordingly, the necessary degree of drying is alleviated and the upper limit of the surface water percentage of the fine aggregate that can be used is also alleviated.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a concrete manufacturing method according to the present invention will be described below with reference to the accompanying drawings. Note that components that are substantially the same as those of the prior art are assigned the same reference numerals, and descriptions thereof are omitted.
[0018]
FIG. 1 is a flowchart showing a procedure of a concrete manufacturing method according to the present embodiment. As can be seen in the figure, in the method for producing concrete according to the present embodiment, first, of the aggregate composed of coarse aggregate and wet fine aggregate, the coarse aggregate is completely dry or close to it. Drying is performed using a drying furnace or the like (step 101). It is desirable to use a coarse aggregate having as high a water absorption as possible, and preferably a high water absorption aggregate or an artificial lightweight aggregate.
[0019]
Next, the coarse aggregate after drying is put into a mixer truck together with the fine aggregate in a wet state, and these are mixed and stirred (step 102).
[0020]
In this way, the surface water of the fine aggregate in the wet state is absorbed by the coarse aggregate that has absorbed water by drying, and eventually the fine aggregate that was initially in the wet state is surface-dried or air-dried. The state changes to a wet state where the surface water content is extremely small.
[0021]
Next, cement is additionally added to the mixer truck and conveyed to the site while mixing and stirring together with the aggregate made of coarse aggregate and fine aggregate (step 103). At this time, since the fine aggregate is in a surface-dried or air-dried state or in a wet state where the surface water ratio is extremely small, the reaction between the cement and the surface water of the fine aggregate is substantially not affected by mixing and stirring with the cement. Does not occur or is greatly suppressed.
[0022]
Next, concrete is produced by introducing water and the necessary admixture into the mixer truck at the site (step 104). If the coarse aggregate and the fine aggregate are in an air-dried state at this stage, the amount of water is appropriately corrected so as to suit the combination of indications.
[0023]
As described above, according to the concrete manufacturing method according to the present embodiment, the coarse aggregate is dried in an absolutely dry state or a state close thereto, and the coarse aggregate is stirred and mixed together with the fine aggregate in a wet state. After that, since it was transported to the site with mixing and stirring together with cement, the fine aggregate was absorbed into the coarse aggregate, so that it was in a surface dry or air dry state or a wet state where the surface water ratio was extremely small. Become.
[0024]
Therefore, even if these coarse and fine aggregates are mixed and agitated with cement and transported to the site for a long time, the reaction between the cement and the fine aggregate surface water is substantially eliminated or greatly suppressed. This makes it possible to significantly extend the limit standing time (the limit time that does not substantially reduce the slump). For example, if the surface water ratio of the fine aggregate can be adjusted to 1% or less, the limit standing time is about 3 hours.
[0025]
Incidentally, in the past, when the surface water content of the fine aggregate was 3% or more, the limit standing time was 1 hour, and long-distance conveyance, which is an advantage of the dry-chatch method, was almost impossible. Also, if the fine aggregate has a surface water content of 3%, if left for 3 hours, the concrete compressive strength will decrease by 20%. If the surface water content is 6%, if left for 6 hours, the concrete compressive strength will decrease by 50%. To do.
[0026]
On the other hand, according to the concrete manufacturing method according to the present embodiment, it is possible to extend the limit neglect time by changing the wet surface of the fine aggregate to a state where the surface water ratio is extremely small. It becomes possible to ensure the slump, air amount and concrete strength as designed with water and AE agent as shown.
[0027]
Further, according to the method for producing concrete according to the present embodiment, the coarse aggregate is dried out of the aggregate composed of the coarse aggregate and the wet fine aggregate. It is possible to improve the drying efficiency rather than partially drying.
[0028]
Moreover, according to the concrete manufacturing method according to the present embodiment, since the high water absorption aggregate or the artificial lightweight aggregate is used for the coarse aggregate, the surface water of the fine aggregate is reduced by the amount of the high water absorption performance. Increases ability to absorb. Therefore, the necessary degree of drying is alleviated and the burden of the drying process is reduced, and the upper limit of the surface water content of the usable fine aggregate is also reduced from 5% to 6%, for example.
[0029]
Here, three concrete blending examples (all slumps 8 cm) are shown in Table 1, and the amount of water absorbable and the amount of water absorbable of the three types of coarse aggregates used in each blend are used as the surface water ratio of the fine aggregate. Table 2 shows the converted values.
[0030]
[Table 1]

[0031]
[Table 2]

[0032]
From Table 2, in the blending examples shown in Table 1, when three types of coarse aggregates of standard aggregate, high-absorbent aggregate, and artificial lightweight aggregate are dried to an absolutely dry state, each is about 1%, It is understood that the surface water of the fine aggregate corresponding to the surface water ratio of 3% and 8% can be absorbed (in other words, the surface water ratio can be reduced by about 1%, 3%, and 8%, respectively). .
[0033]
In this embodiment, a part of the aggregate composed of the coarse aggregate and the fine aggregate in the wet state is dried. However, even if all the aggregate is dried, the cement is additionally added and mixed and stirred. Needless to say, the setting of cement can be prevented. In this configuration, it is possible to omit the mixing and stirring step between the aggregates.
[0034]
【The invention's effect】
As described above, according to the concrete manufacturing method of the present invention according to

claims

1 and 2 , the fine aggregate in a wet state is either surface-dried or air-dried or has a very low surface water content. Become wet. Therefore, even if these coarse and fine aggregates are mixed and agitated with cement and transported to the site for a long time, the reaction between the cement and the fine aggregate surface water is substantially eliminated or greatly suppressed. As a result, it is possible to significantly extend the limit leaving time, and as a result, ensure the slump, air amount and concrete strength as designed with water and AE agent as shown in the composition even at a distant site. It becomes possible.
[0035]
Moreover, according to the concrete manufacturing method of the present invention according to claim 3 , it is possible to improve the drying efficiency rather than drying a part of the fine aggregate in a wet state.
[0036]
Further, according to the concrete production method of the present invention according to claim 4 , the ability to absorb the surface water of the fine aggregate is increased by the amount of water absorption performance is high, and the necessary degree of drying is relieved, There is also an effect that the upper limit of the surface water ratio of the usable fine aggregate is relaxed.
[0037]
[Brief description of the drawings]
FIG. 1 is a flowchart showing a procedure of a concrete manufacturing method according to the present embodiment.

Claims

By drying a part of the aggregate composed of the coarse aggregate and the wet fine aggregate having a surface water ratio of 6% or less so as to be in an absolutely dry state or an air dry state, and then mixing and stirring the aggregate The surface water of the wet fine aggregate is absorbed into the coarse aggregate or the dried fine aggregate, and then the aggregate is transported with mixing and stirring together with cement, and then water and necessary mixing are performed. A method for producing concrete, characterized in that an agent is added to produce concrete.

Fine aggregate that is not dried by drying a part of the aggregate composed of coarse aggregate and wet fine aggregate so as to be in an absolutely dry state or air-dried state, and then mixing and stirring the aggregate The surface water content of the concrete is reduced by 1% to 8%, and then the aggregate is conveyed while being mixed and stirred together with the cement, and then concrete is produced by adding water and the necessary admixture. Manufacturing method.

The coarse aggregate is dried so that the absolute dry state or air dried state, claim 1 The crude aggregate mix stirred with fine aggregate of the wet state before the mixing and stirring step with the cement or 2 The manufacturing method of the concrete as described.

Method for producing concrete according to claim 3, wherein the use of artificial lightweight aggregate to the coarse aggregate.