Solidfication and reuse of coal fly ash by heating-compressive method
Grant-in-Aid for Scientific Research (C)
|Allocation Type||Single-year Grants|
|Research Institution||Anan College of Technology|
NISHIOKA Mamoru Anan College of Technology, Mechanical Engineering, Associate Professor, 機械工学科, 助教授 (30270341)
AMO Kazuo Anan College of Technology, Construction Systems Engineering, Associate Professo, 建設システム工学科, 助教授 (40043989)
|Project Period (FY)
1996 – 1997
Completed(Fiscal Year 1997)
|Budget Amount *help
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1997 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1996 : ¥900,000 (Direct Cost : ¥900,000)
|Keywords||fly ash / slag / non-JIS ash / solid body / heat / compression / solidfication / compressive strength / 加熱・圧縮 / コンクリート / シリカフューム|
In this study of the first year, coal fly ash with some additives was solidified by a heat-compressive method at reaction temperatures of 100 - 250 degree C and at compressive strengths of 0 - 10 MPa. The ash and silica fume or the slag powder 5 -20 wt%) was kneaded well with NaOH solution (15% of powder weight) to prepare the starting material. The mixed powder was put into the autoclave, which has a cylindrical shape with a 20 mm of inner diameter, and compressed at 5 MPa because of the constriction of the packing of the autoclave. Then it was continuously compressed at the certain pressure with an oil cylinder by oil pump and was heated to a planned temperature.
The solidified bodies were evaluated by the compressive strength and the tensile strength.
Density of the solidified body was measured from its weight and apparent volume after drying at 60 dgree C.And static leach tests for main elements of starting material were performed.
The following results were obtained ;
In the case of s
ilica fume as additive, the compressive strength was increased with the content. When the starting materials was solidified at 140 degree C, at 4 MPa, and the content of 10%, the compressive strength was much higher and the density was lower than that ordinary fly ash concrete. The results of leaching tests suggested that the leached amount of main elements for solid body affects the compressive strength.
In the case of the slag as additive, the compressive strength of the solid body reached 64.3 MPa, when solid conditions were at 230 degree C at 10 MPa, and addition of the slag powder with smaller particle (8000cm2/g), And the solid body by above conditions has higher of twice compressive strength, same level of the tensile strength, and lower density than that of ordinary fly ash concrete.
In the study of second year, the solid bodies with large diameter (50 mm) were produced with larger equipment than the first year. The conditions for solid were considered by results for smaller solid bodies. Especially non- JIS fly ash, which is more problem about the disposal, was used in this study. An alteration test under the elevated temperature at 100 - 200 degree C for the fly ash was performed with an Teflon autoclave in order to confirm the long period working. From results of last year, the starting material was solidified the tenperature at 150 - 250 degree C, the compression at 10 MPa, and using the slag with the surface area of 8000cm2 per 1g weight.
The following results were obtained ;
(1)The solid body with a high compressive strength of 50 MPa and a light density of 1.80 was obtained under the reaction temperature of 250 degree C.
(2)The compressive strength of solid body was increased with the content of slag powder. When the content of 10% reached, the compressive strength was extremely increased. From economical and the strength view points. it suggested that the optimum content of slag powder is 20%.
(3)The tensile strength was increased about 2.9 MPa with the increasing of reaction temperature up to 225 degree C.And the ratio of tensile strength / compressive strength showed 1/20. The value is much smaller than that of normal concrete block.
(4)The alteration of the coal fly ash in alkaline (NaOH) solution produced some synthesis zeolites under conditions at the reaction temperature of 150 degree C and for the reaction time of 30 minutes. Less
Research Output (10results)