JP3556155B2 - Granulated / hardened material of coal ash blended as supplementary material with roadbed material, method of manufacturing the same, roadbed material blended with granulated / hardened material of coal ash as supplementary material - Google Patents
Granulated / hardened material of coal ash blended as supplementary material with roadbed material, method of manufacturing the same, roadbed material blended with granulated / hardened material of coal ash as supplementary material Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、道路用の路盤材に補足材として配合する石炭灰の造粒・硬化物、その製造方法、石炭灰の造粒・硬化物を補足材として配合した道路用の路盤材に関する。
【０００２】
【従来の技術】
石炭は、石油代替エネルギー資源として、その重要性が見直され、石炭火力発電所の建設が各地で行われている。それらの石炭火力発電所の稼働により、極めて多量の石炭灰が発生しており、その有効利用が検討されている。
石炭灰を多量に実用化している例としては、セメント原料に利用している例があるが利用数量において既に限界に達しており、多量に活用できる新たな用途の開発が望まれているのが現状である。
一方、道路用の路盤材は、「アスファルト舗装要綱（平成４年版）」に記載されいるように天然砕石、鉄鋼スラグ、再生骨材等を破砕して用いるクラッシャランと呼ばれる路盤材、このクラッシャランをベースとして強度をあげる目的で粒度調整した粒度調整鉄鋼スラグ、水硬性を付加し高強度が得られるようにするため、水硬性高炉スラグを使用し、かつ粒度調整を行った水硬性粒度調整鉄鋼スラグなどがある。
【０００３】
通常、路盤は路床と称する地面上に、下層路盤と上層路盤に分けて施工される。下層路盤材によってある程度の支持力を確保し、その上に強度の大きい上層路盤材を施工して所要の支持力を確保するものである。下層路盤材として使用されるクラッシャランは、安価であるが強度は高くない。上層路盤材として使用される粒度調整鉄鋼スラグ、水硬性粒度調整鉄鋼スラグなどは高強度の材料である。道路用の路盤材は、その使用量が極めて多量であることから、石炭灰を多量に活用できる用途と考えられ、従来から石炭灰を路盤材に利用する研究が行われており、発明もなされている。特開平３−２０８９０１号公報において開示された発明は、石炭灰をそのまま鉄鋼スラグを主成分とする路盤材に配合するもので、石炭灰の使用量は２〜７重量％程度と少ない。
また、微細な石炭灰を含有しているため、路盤材の運搬や施工の際の発じんをもたらし、周辺環境を汚染するという問題を生じるため使用場所が限定されると考えられる。
特開平１−３２０２４５号公報において開示された発明は、石炭灰に固化剤を加えて水を添加して混合・混練後に成形し、養生によって硬化体を作り、その硬化体を破砕して得た石炭灰硬化体を、路盤材に１０重量％〜３０重量％配合するもので、石炭灰硬化体の使用量は多い。
しかしながら、破砕費用が必要であることや、破砕の際に発生する微細で軽い石炭灰を含有するため、路盤材の運搬や施工の際の発じんの原因となって、周辺環境を汚染するという問題を生じるため使用場所が限定される。
【０００４】
【発明が解決しようとする課題】
上述したように、多量に発生している石炭灰を、路盤材に補足材として配合し施工時にも問題を生じることなく活用できる技術が具現化できれば、石炭灰を多量に活用できる道が開けることになる。従来の石炭灰の活用方法は、石炭灰をそのまま路盤材に補足材として配合する方法と、固化し粉砕した石炭灰を路盤材に補足材として配合する方法の２通りがある。
前者は、路盤材へ配合できる石炭灰が２〜７重量％と少ないことに加え、微細で軽い石炭灰がそのままの状態で路盤材中に存在するため、路盤材の運搬や施工に際して、石炭灰の発じんによる周辺環境の汚染という極めて深刻な状況をもたらす。
後者は、路盤材へ配合できる石炭灰が１０〜３０重量％と多いが、製造工程が複数工程となり製造コストが高価となることに加え、破砕の際に発生する微細で軽い石炭灰を含有するため、路盤材の運搬や施工に際して石炭灰の発じんによる周辺環境の汚染という問題を生じる。
【０００５】
本発明の課題は、石炭灰を路盤材の補足材として多量に配合しても、路盤材の運搬や施工に際して粉じんによる周辺環境の汚染のない石炭灰の造粒・硬化物及びその石炭灰の造粒・硬化物を配合した路盤材を提供することにある。また上記石炭灰の造粒・硬化物を安価に製造する方法を提供することにある。
【０００６】
【課題を解決するための手段】
本発明者は、まず施工時等に際して発じんを生じることなく、かつ路盤材の品質向上にも効果のある石炭灰の造粒・硬化物について鋭意検討の結果、「アスファルト舗装要綱（平成４年版）」に記載されている路盤材の粒度分布に関する規格において、路盤材の強度に影響の強い２０ｍｍ以下の粒度分布となり、「アスファルト舗装要綱（平成４年版）」に記載されている上層路盤材の一軸圧縮強度１．２ＭＰａ 相当の強度を持つような石炭灰の造粒・硬化物を用いれば、路盤材の強度を改善できることを見出した。
そして、３０μｍ前後という微細な粒子であり、かさ密度も０．７ｇ／ｃｍ３ という極めて軽い粒子により構成されている石炭灰にセメントを加えて０．３ｍｍ以上の粒状物に造粒し、硬化させた石炭灰の造粒・硬化物であれば、運搬や敷きならしに際して発じんを防止できることを見出した。この発じん防止の技術は、周知のストークスの式において粒子径を大きくして粒子の沈降速度を増加させる原理を活用したものである。
また、本発明者は、単一の混練設備に石炭灰と石炭灰の種類に応じて適当量のセメントを供給し、粉体を混合し、その混合物に適当量の水を添加しながら混練することによって０．３ｍｍ〜２０ｍｍの造粒物を得ることができ、この造粒物を適当期間、自然養生することで圧潰強度１．２ＭＰａ 以上とすることができることを見出した。
【０００７】
本発明は、上記の知見に基づきなされたもので、本発明の要旨は、
（１）クラッシャラン、粒度調整鉄鋼スラグ、水硬性粒度調整鉄鋼スラグ等の道路用の路盤材に補足材として配合する石炭灰の造粒・硬化物であって、その粒度範囲が０．３ｍｍ〜２０ｍｍで粒度分布がＪＩＳ Ａ ５０１５で定める規格にそったもので、且つ圧潰強度が１．２ＭＰａ以上であることを特徴とするクラッシャラン、粒度調整鉄鋼スラグ、水硬性粒度調整鉄鋼スラグ等の道路用の路盤材に補足材として配合する石炭灰の造粒・硬化物。
（２）混練設備に石炭灰とセメントを供給して、粉体を混合し、その混合物に水を添加しながら混練し、混練を継続することによって造粒を行い、０．３ｍｍ〜２０ｍｍの粒状に造粒が進んだ段階で、混練設備から排出し自然養生により硬化させて圧潰強度を１．２ＭＰａ以上且つ粒度分布がＪＩＳ Ａ ５０１５で定める規格にそったものとしたことを特徴とするクラッシャラン、粒度調整鉄鋼スラグ、水硬性粒度調整鉄鋼スラグ等の道路用の路盤材に補足材として配合する石炭灰の造粒・硬化物の製造方法。
（３）石炭灰が微粉炭燃焼ボイラーで発生した石炭灰であり、石炭灰とセメントの混合物中のＣａＯ成分が１５重量％以上であり、養生期間が１４日以上であることを特徴とする上記（２）に記載のクラッシャラン、粒度調整鉄鋼スラグ、水硬性粒度調整鉄鋼スラグ等の道路用の路盤材に補足材として配合する石炭灰の造粒・硬化物の製造方法。
（４）石炭灰が流動床燃焼ボイラーで発生した石炭灰であり、石炭灰とセメントの混合物中のＣａＯ成分が２０重量％以上であり、養生期間が１４日以上であることを特徴とする上記（２）に記載のクラッシャラン、粒度調整鉄鋼スラグ、水硬性粒度調整鉄鋼スラグ等の道路用の路盤材に補足材として配合する石炭灰の造粒・硬化物の製造方法。
（５）クラッシャラン、粒度調整鉄鋼スラグ、水硬性粒度調整鉄鋼スラグ等の道路用の路盤材に、石炭灰の造粒・硬化物を補足材として配合した道路用の路盤材であって、その石炭灰の造粒・硬化物の粒度範囲が０．３ｍｍ〜２０ｍｍで粒度分布がＪＩＳ Ａ ５０１５で定める規格にそったもので、且つ圧潰強度が１．２ＭＰａ以上であることを特徴とする石炭灰の造粒・硬化物を補足材として配合した道路用の路盤材。
（６）石炭灰の造粒・硬化物の配合量は５０重量％以下であることを特徴とする上記（５）に記載の石炭灰の造粒・硬化物を補足材として配合した道路用の路盤材。
にある。
【０００８】
【発明の実施の形態】
石炭灰に添加するセメントは、石炭灰中のＣａＯ成分の量によってその添加量を設定すれば、粒状物の破損による微細な石炭灰の発生が防止できること及び、セメントの使用量を最も経済的なものとできる。
すなわち、図１は石炭灰とセメントの混合物中のＣａＯ含有量と石炭灰の造粒・硬化物の圧潰強度の関係を示すものであるが、「アスファルト舗装要綱（平成４年版）」に記載されている上層路盤材の一軸圧縮強度１．２ＭＰａ 相当の強度を持つ石炭灰の造粒・硬化物とするためには、微粉炭燃焼ボイラーで発生した石炭灰（以下、微粉炭灰と称する）を原料として石炭灰の造粒・硬化物をつくる場合には、石炭灰とセメントの混合物中のＣａＯが、１５重量％となるようにセメントの添加量を定める。
また、流動床燃焼ボイラーで発生した石炭灰（以下流動床灰と称する）を原料として石炭灰の造粒・硬化物をつくる場合には、石炭灰とセメントの混合物中のＣａＯが、２０重量％となるようにセメントの添加量を定める。
石炭灰とセメントの混合物に添加する水分量は、石炭灰の種類などに対応して設定する。その水分量の範囲は、４５重量％〜５５重量％の範囲である。
【０００９】
混練設備としては、セラミックスの原料混合等に使用されている解砕混練設備又は、コンクリートミキサー等に使用されているスパイラルフローミキサーを用いる。解砕混練設備は、微粉炭灰と流動床灰の両方に適用できるが、スパイラルフローミキサーは流動床灰の処理に適している。
【００１０】
造粒した０．３ｍｍ〜２０ｍｍの粒状物は、屋外で自然養生を行う。図２は石炭灰の造粒・硬化物の養生日数と圧潰強度の関係を示すものであるが、養生を開始してから１４日を経過すると圧潰強度は飽和点に達することから、養生日数は１４日間とする。
【００１１】
自然養生してつくった０．３ｍｍ〜２０ｍｍの粒状の石炭灰の造粒・硬化物を、上層路盤材として使用される水硬性粒度調整鉄鋼スラグと、下層路盤材として使用されるクラッシャラン鉄鋼スラグに配合した。
図３に石炭灰の造粒・硬化物の配合率と路盤材の修正ＣＢＲ及び一軸圧縮強さの関係を示す。
石炭灰の造粒・硬化物の配合率が１０重量％〜５０重量％の範囲であれば、配合しない場合に比べて遜色がない。修正ＣＢＲ及び一軸圧縮強さは、石炭灰の造粒・硬化物の配合率に連動して高くなるが、３０重量％で飽和状態となり、３０重量％をこえると低下し、配合しない場合と同等となる。
石炭灰の造粒・硬化物の配合率は、５０重量％以下であればよく、特に３０重量％を配合することによって、修正ＣＢＲ及び一軸圧縮強さが最高となることから、路盤材の品質保証の確度向上という観点から、配合率は３０重量％が望ましいことが理解できる。
【００１２】
【実施例】
以下に実施例により、本発明を具体的に説明する。
（原料）実施に際して使用した石炭灰の分析結果を表１に、石炭灰の造粒・硬化物を配合する前の路盤材の分析結果を表２に示す。セメントとして、市販されているポルトランドセメントを使用した。
【００１３】
【表１】
【表２】
（実施例１）
混練設備として解砕混練設備を用いた。この混練設備に微粉炭灰とポルトランドセメントを供給した。ポルトランドセメントの量は、図１に基づき微粉炭灰とポルトランドセメントの混合物中のＣａＯ成分が１５重量％となるようにした。
混練設備を稼働し、微粉炭灰とポルトランドセメントを１０秒間混合した。
次いで、水を徐々に添加しながら混練し、さらに混練を継続すると造粒が始まり、６分後に停止して造粒物を排出した。水分量は粒状物の水分量が４５重量％となるように添加した。
混練設備より排出した粒状物を１４日間屋外で自然養生を行い粒状の石炭灰の造粒・硬化物を得た。石炭灰の造粒・硬化物の粒度分布と圧潰強度のデータを表３にしめすが、目標通りの圧潰強度１．２ＭＰａ 以上と、目標通りの粒度分布０．３ｍｍ〜２０ｍｍの材料を得ることができた。
このように製造した石炭灰の造粒・硬化物をクラッシャラン鉄鋼スラグと水硬性粒度調整鉄鋼スラグに各々３０重量％配合した。その路盤材の修正ＣＢＲと一軸圧縮強さを表４に示すが、路盤材としての規格値以上の強度となっている。
本路盤材を用いて施工する際の発じん状態を目視で観察した結果、ダンプトラックで運搬する工程とダンプトラックから地上に荷おろしする工程、及びモーターグレーダーによる敷均し工程の何れにおいても、従来の路盤材を用いた場合に比べて遜色はなかった。
【００１６】
【表３】
【表４】
（実施例２）
混練設備としてスパイラルフローミキサーを使用した。この混練設備に流動床灰とポルトランドセメントを供給した。ポルトランドセメントの量は、図１に基づき流動床灰とポルトランドセメントの混合物中のＣａＯ成分が２０重量％となるようにした。
混練設備を稼働し、流動床灰とポルトランドセメントを１０秒間混合した。次いで、水を徐々に添加しながら混練し、混練を継続すると造粒が始まり、６分後に停止して造粒物を排出した。水分量は粒状物の水分量が５０重量％となるように添加した。
混練設備より排出した粒状物を１４日間屋外で自然養生を行い粒状の石炭灰の造粒・硬化物を得た。石炭灰の造粒・硬化物の粒度分布と圧潰強度のデータを表５に示すが、目標通りの圧潰強度１．２ＭＰａ 以上と、目標通りの粒度分布０．３ｍｍ〜２０ｍｍの材料を得ることができた。
このように製造した石炭灰の造粒・硬化物を、クラッシャラン鉄鋼スラグと水硬性粒度調整鉄鋼スラグに各々３０重量％配合した。その路盤材の修正ＣＢＲと一軸圧縮強さを表６に示すが、路盤材としての規格値以上の強度となっている。本路盤材を用いて施工する際の発じん状態を目視で観察した結果、ダンプトラックで運搬する工程とダンプトラックから地上に荷おろしする工程、及びモーターグレーダーによる敷均し工程の何れにおいても、従来の路盤材を用いた場合に比べて遜色はなかった。
【００１９】
【表５】
【表６】
【発明の効果】
本発明は、上記した従来の補足材の課題を全てにわたり解決した補足材と、その補足材を配合した路盤材を提供するものである。即ち、石炭灰をセメントと水を用いて、０．３ｍｍ〜２０ｍｍの粒状の造粒物をつくり、１４日間の自然養生によって圧潰強度を１．２ＭＰａ 以上とした硬化物として路盤材の補足材に使用するものであるから、微細で軽い石炭灰を含有していないため、路盤材の運搬や施工に際して石炭灰の発じんによる周辺環境の汚染という問題も生じない。加えて路盤材の強度も規格値を越える成績を得ることができる。
本発明の０．３ｍｍ〜２０ｍｍの粒状の造粒・硬化物の製造は、単一の混練設備のみを用いて行うため製造工程がシンプルであること、及び破砕工程が不要であることから設備費も安価であり、製造コストも安価であることから安価な補足材を提供できることになる。
上述したように、本発明による路盤材用の補足材と、その補足材を配合した路盤材は、施工性と環境保全に優れ、規格に適合した強度も確保できることに加えて安価な路盤材を提供できるため、実用的な石炭灰の多量利用の道を開くことができる。
【図面の簡単な説明】
【図１】石炭灰とセメントの混合物中のＣａＯ含有量と石炭灰の造粒・硬化物の圧潰強度の関係を示すものである。
【図２】石炭灰の造粒・硬化物の養生日数と圧潰強度の関係を示すものである。
【図３】石炭灰の造粒・硬化物の配合率と路盤材の修正ＣＢＲ及び一軸圧縮強さの関係を示すものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a granulated and hardened material of coal ash blended as a supplementary material with a roadbed material for roads, a method for producing the same, and a roadbed material for a road blended with a granulated and hardened material of coal ash as a supplementary material.
[0002]
[Prior art]
The importance of coal as an alternative energy resource to oil is being reviewed, and coal-fired power plants are being constructed in various places. An extremely large amount of coal ash has been generated by the operation of these coal-fired power plants, and its effective use is being studied.
As an example of using coal ash in large quantities, there is an example where coal ash is used as a raw material for cement, but the amount of coal ash has already reached its limit, and the development of new applications that can be utilized in large quantities is desired. It is the current situation.
On the other hand, as for the roadbed material for roads, as described in “Asphalt Pavement Outlines (1994 edition)”, a roadbed material called crusher orchid that uses crushed natural crushed stone, steel slag, recycled aggregate, etc., and is based on this crusher orchid Particle size-adjusted steel slag with particle size adjustment for the purpose of increasing strength, hydraulic particle size-adjusted steel slag that uses hydraulic blast furnace slag and has been subjected to particle size adjustment to add hydraulic property and obtain high strength There is.
[0003]
Generally, a roadbed is constructed on a ground called a subgrade, divided into a lower roadbed and an upper roadbed. The lower roadbed material secures a certain level of supporting force, and a high-strength upper roadbed material is constructed thereon to secure the required supporting force. Crusher orchids used as lower roadbed materials are inexpensive but not strong. Particle size-adjusted steel slag and hydraulic particle size-adjusted steel slag used as upper subbase materials are high-strength materials. Roadbed material is considered to be an application that can utilize a large amount of coal ash because the amount of roadbed material used is extremely large.There have been studies on the use of coal ash for roadbed materials, and inventions have been made. ing. The invention disclosed in Japanese Patent Application Laid-Open No. 3-208901 is a method in which coal ash is directly added to a roadbed material mainly composed of steel slag, and the amount of coal ash used is as small as about 2 to 7% by weight.
In addition, since fine coal ash is contained, dust is generated during transportation and construction of the roadbed material, causing a problem of contaminating the surrounding environment.
The invention disclosed in JP-A-1-320245 is obtained by adding a solidifying agent to coal ash, adding water, mixing and kneading, molding, curing, forming a cured product, and crushing the cured product. The hardened coal ash is blended in the roadbed material in an amount of 10% by weight to 30% by weight, and the used amount of the hardened coal ash is large.
However, the cost of crushing is necessary, and because it contains fine and light coal ash generated during crushing, it causes dust during transportation and construction of roadbed materials and pollutes the surrounding environment. Places of use are limited due to problems.
[0004]
[Problems to be solved by the invention]
As mentioned above, if technology that can use a large amount of coal ash as a supplementary material to roadbed material and can utilize it without causing problems during construction can be realized, a way to utilize a large amount of coal ash will be opened. become. Conventional methods of utilizing coal ash include two methods: a method in which coal ash is directly added to a roadbed material as a supplementary material, and a method in which solidified and pulverized coal ash is added to a roadbed material as a supplementary material.
In the former, the amount of coal ash that can be blended into the roadbed material is as small as 2 to 7% by weight, and fine and light coal ash is present in the roadbed material as it is. The extremely serious situation of pollution of the surrounding environment due to the generation of dust.
In the latter case, the amount of coal ash that can be blended into the roadbed material is as large as 10 to 30% by weight, but in addition to the multiple manufacturing steps, the manufacturing cost is high, and fine and light coal ash generated during crushing is contained. Therefore, there is a problem of pollution of the surrounding environment due to the generation of coal ash during transportation and construction of the roadbed material.
[0005]
It is an object of the present invention to provide a granulated / hardened product of coal ash that does not contaminate the surrounding environment due to dust during transportation and construction of the roadbed material even when a large amount of coal ash is blended as a supplementary material for the roadbed material, and that the coal ash It is an object of the present invention to provide a roadbed material containing a granulated and cured product. Another object of the present invention is to provide a method for inexpensively producing a granulated and hardened material of the above coal ash.
[0006]
[Means for Solving the Problems]
The inventor of the present invention has conducted intensive studies on granulated and hardened coal ash that does not generate dust during construction and is also effective in improving the quality of roadbed materials. )), The particle size distribution of 20 mm or less, which has a strong influence on the strength of the roadbed material, is specified in the standard for the particle size distribution of the roadbed material. It has been found that the strength of the roadbed material can be improved by using a granulated and hardened material of coal ash having a strength equivalent to the uniaxial compressive strength of 1.2 MPa.
Cement is added to coal ash, which is composed of extremely light particles of about 30 μm and very light particles having a bulk density of about 0.7 g / cm 3 , and granulates into granules of 0.3 mm or more and hardens. It has been found that a granulated and hardened product of coal ash can prevent dust generation during transportation and laying. This dust prevention technology utilizes the principle of increasing the particle diameter and increasing the sedimentation speed of particles in the well-known Stokes' formula.
In addition, the present inventor supplies an appropriate amount of cement according to the type of coal ash and coal ash to a single kneading facility, mixes the powder, and kneads the mixture while adding an appropriate amount of water. As a result, a granulated product of 0.3 mm to 20 mm can be obtained, and it has been found that a crushing strength of 1.2 MPa or more can be obtained by naturally curing the granulated product for an appropriate period.
[0007]
The present invention has been made based on the above findings, the gist of the present invention,
(1) A granulated and hardened material of coal ash to be added as a supplement to roadbed materials such as crusher orchid, grain size adjusted steel slag, hydraulic grain size adjusted steel slag, etc., and the grain size range is 0.3 mm to 20 mm. A roadbed such as a crusher orchid, a grain-size-adjusted steel slag, a hydraulic grain-size-adjusted steel slag, etc., characterized in that the grain size distribution conforms to the standard defined by JIS A 5015 and the crushing strength is 1.2 MPa or more. Granulated and hardened coal ash to be added as a supplement to wood.
(2) Coal ash and cement are supplied to a kneading facility, powder is mixed, kneaded while adding water to the mixture, and granulation is performed by continuing kneading to obtain a granule of 0.3 mm to 20 mm. At the stage where granulation has advanced, the crusher orchid is discharged from the kneading equipment and hardened by natural curing to have a crushing strength of 1.2 MPa or more and a particle size distribution in accordance with the standard defined by JIS A 5015 , A method for producing a granulated / hardened product of coal ash to be added as a supplement to roadbed materials such as particle size-adjusted steel slag and hydraulic particle size-adjusted steel slag.
(3) The coal ash generated by the pulverized coal combustion boiler, wherein the CaO component in the mixture of coal ash and cement is 15% by weight or more, and the curing period is 14 days or more. A method for producing a granulated and hardened product of coal ash to be added as a supplement to roadbed materials such as crusher orchid, grain-size-adjusted steel slag and hydraulic grain-size-adjusted steel slag according to (2).
(4) The coal ash generated by the fluidized bed combustion boiler, wherein the CaO component in the mixture of coal ash and cement is 20% by weight or more, and the curing period is 14 days or more. A method for producing a granulated and hardened product of coal ash to be added as a supplement to roadbed materials such as crusher orchid, grain-size-adjusted steel slag and hydraulic grain-size-adjusted steel slag according to (2).
(5) A roadbed material obtained by blending a granulated and hardened material of coal ash as a supplementary material with a roadbed material such as crusher orchid, grain size adjusted steel slag, hydraulic grain size adjusted steel slag, and the like. A coal ash characterized in that the granulated and cured ash has a particle size range of 0.3 mm to 20 mm, a particle size distribution conforming to the standard defined by JIS A 5015 , and a crushing strength of 1.2 MPa or more. Roadbed material containing granulated / hardened material as a supplement.
(6) The amount of the granulated and hardened material of coal ash is not more than 50% by weight, and the granulated and hardened material of coal ash according to (5) is used as a supplementary material for roads. Subbase material.
It is in.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
If the amount of cement added to coal ash is set according to the amount of CaO component in coal ash, it is possible to prevent the generation of fine coal ash due to breakage of particulate matter, and to reduce the amount of cement used in the most economical way. I can do it.
That is, FIG. 1 shows the relationship between the CaO content in the mixture of coal ash and cement and the crushing strength of the granulated and hardened material of coal ash, which is described in the “Asphalt Pavement Guidelines (1994 Edition)”. In order to obtain a coal ash granulated and hardened product having a strength equivalent to the uniaxial compressive strength of 1.2 MPa for the upper roadbed material, coal ash generated by a pulverized coal combustion boiler (hereinafter referred to as pulverized coal ash) is used. When a granulated and hardened material of coal ash is produced as a raw material, the amount of cement added is determined so that CaO in a mixture of coal ash and cement becomes 15% by weight.
In the case where a coal ash is granulated and hardened using coal ash generated in a fluidized bed combustion boiler (hereinafter referred to as fluidized bed ash) as a raw material, CaO in a mixture of coal ash and cement contains 20% by weight. Determine the amount of cement to be added.
The amount of water added to the mixture of coal ash and cement is set according to the type of coal ash and the like. The range of the water content is in the range of 45% by weight to 55% by weight.
[0009]
As the kneading equipment, a crushing kneading equipment used for mixing raw materials of ceramics or a spiral flow mixer used for a concrete mixer or the like is used. The crushing and kneading equipment can be applied to both pulverized coal ash and fluidized bed ash, while the spiral flow mixer is suitable for treating fluidized bed ash.
[0010]
The granulated granules of 0.3 mm to 20 mm undergo natural curing outdoors. FIG. 2 shows the relationship between the number of days of curing and the crushing strength of the granulated / hardened material of coal ash. Since the crushing strength reaches a saturation point after 14 days from the start of curing, the number of days of curing is 14 days.
[0011]
The granulated and hardened material of 0.3mm to 20mm granular coal ash made by natural curing is converted into hydraulic graded steel slag used as upper subgrade material and crusher-run steel slag used as lower subgrade material. Was blended.
FIG. 3 shows the relationship between the mixing ratio of the granulated and hardened material of coal ash, the modified CBR of the roadbed material, and the uniaxial compressive strength.
When the blending ratio of the granulated and hardened material of coal ash is in the range of 10% by weight to 50% by weight, there is no inferiority to the case where no blending is performed. The modified CBR and unconfined compressive strength increase in conjunction with the blending ratio of the granulated and hardened coal ash, but become saturated at 30% by weight, fall below 30% by weight, and are equivalent to those without blending. It becomes.
The blending ratio of the coal ash granulated / hardened product may be 50% by weight or less, and in particular, by blending 30% by weight, the corrected CBR and the uniaxial compressive strength become the highest, so that the quality of the roadbed material is improved. From the viewpoint of improving the accuracy of the guarantee, it can be understood that the mixing ratio is desirably 30% by weight.
[0012]
【Example】
Hereinafter, the present invention will be described specifically with reference to examples.
(Raw material) The analysis results of the coal ash used in the implementation are shown in Table 1, and the analysis results of the roadbed material before blending the granulated and hardened material of the coal ash are shown in Table 2. A commercially available Portland cement was used as the cement.
[0013]
[Table 1]
[Table 2]
(Example 1)
A crushing kneading equipment was used as the kneading equipment. Fine coal ash and Portland cement were supplied to the kneading equipment. The amount of Portland cement was adjusted so that the CaO component in the mixture of pulverized coal ash and Portland cement was 15% by weight based on FIG.
The kneading equipment was operated, and the fine coal ash and Portland cement were mixed for 10 seconds.
Next, the mixture was kneaded while gradually adding water, and when the kneading was continued, granulation started. After 6 minutes, the granulation was stopped and the granulated product was discharged. The water content was added such that the water content of the granular material was 45% by weight.
The granular material discharged from the kneading equipment was naturally cured outdoors for 14 days to obtain a granulated and hardened material of granular coal ash. Table 3 shows the data on the particle size distribution and crushing strength of the granulated and hardened material of coal ash, and it is possible to obtain a material having a target crushing strength of 1.2 MPa or more and a target particle size distribution of 0.3 mm to 20 mm. did it.
The granulated and hardened material of the coal ash produced in this manner was blended with 30% by weight of each of the crusher-run steel slag and the hydraulically sized steel slag. Table 4 shows the modified CBR and the unconfined compressive strength of the roadbed material. The strength is higher than the standard value as the roadbed material.
As a result of visually observing the dusting state when constructing using this roadbed material, in both the process of transporting with a dump truck, the process of unloading from the dump truck to the ground, and the leveling process with a motor grader, There was no inferiority to the case using the conventional roadbed material.
[0016]
[Table 3]
[Table 4]
(Example 2)
A spiral flow mixer was used as the kneading equipment. Fluidized bed ash and Portland cement were supplied to the kneading facility. Based on FIG. 1, the amount of Portland cement was such that the CaO component in the mixture of fluidized bed ash and Portland cement was 20% by weight.
The kneading equipment was operated, and the fluidized bed ash and Portland cement were mixed for 10 seconds. Next, the mixture was kneaded while gradually adding water, and when the kneading was continued, granulation started, stopped after 6 minutes, and the granulated material was discharged. The water content was added such that the water content of the granular material was 50% by weight.
The granular material discharged from the kneading equipment was naturally cured outdoors for 14 days to obtain a granulated and hardened material of granular coal ash. Table 5 shows the data of the particle size distribution and crushing strength of the granulated / hardened product of coal ash, and it is possible to obtain a material having a crushing strength of 1.2 MPa or more as intended and a grain size distribution of 0.3 mm to 20 mm as intended. did it.
The granulated and hardened material of the coal ash produced as described above was blended with 30% by weight of each of the crusher-run steel slag and the hydraulic sizing steel slag. Table 6 shows the modified CBR and unconfined compressive strength of the roadbed material. The strength is higher than the standard value for the roadbed material. As a result of visually observing the dusting state when constructing using this roadbed material, in both the process of transporting with a dump truck, the process of unloading from the dump truck to the ground, and the leveling process with a motor grader, There was no inferiority to the case using the conventional roadbed material.
[0019]
[Table 5]
[Table 6]
【The invention's effect】
The present invention provides a supplemental material that solves all of the problems of the conventional supplementary material described above, and a roadbed material containing the supplementary material. That is, coal ash is formed into granular granules of 0.3 mm to 20 mm using cement and water, and as a cured material having a crushing strength of 1.2 MPa or more by natural curing for 14 days as a supplementary material for roadbed material. Since it is used, it does not contain fine and light coal ash, so that there is no problem of contamination of the surrounding environment due to the generation of coal ash during transportation and construction of roadbed materials. In addition, the results of the strength of the roadbed material exceeding the standard value can be obtained.
The production of 0.3 mm to 20 mm granular granulated / hardened product of the present invention is performed using only a single kneading facility, so that the production process is simple, and the facility cost is low because the crushing process is unnecessary. Inexpensive supplements can be provided because of the low production cost and low production cost.
As described above, a supplementary material for a roadbed material according to the present invention, and a roadbed material containing the supplementary material, are excellent in workability and environmental protection, and in addition to ensuring strength in conformity with standards, inexpensive roadbed material can be obtained. Because it can be provided, it is possible to open the way to use large amounts of practical coal ash.
[Brief description of the drawings]
FIG. 1 shows the relationship between the CaO content in a mixture of coal ash and cement and the crushing strength of a granulated and hardened material of coal ash.
FIG. 2 shows the relationship between the number of days for curing and the crushing strength of a granulated and hardened material of coal ash.
FIG. 3 shows the relationship between the mixing ratio of a granulated and hardened material of coal ash, the modified CBR of a roadbed material, and the uniaxial compressive strength.
Claims (6)
Ａ ５０１５で定める規格にそったもので、且つ圧潰強度が１．２ＭＰａ以上であることを特徴とする石炭灰の造粒・硬化物を補足材として配合した道路用の路盤材。Roadbed subgrade material containing granulated and hardened material of coal ash as a supplement to road subgrade material such as crusher orchid, grain size adjusted steel slag, hydraulic grain size adjusted steel slag, etc. The particle size range of the particles / cured product is 0.3mm to 20mm and the particle size distribution is JIS
A roadbed material containing a granulated and hardened material of coal ash as a supplement, characterized in that it complies with the standard specified in A5015 and has a crushing strength of 1.2 MPa or more.
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