Creation of concrete products reusing melting slag from waste incineration ash

Transcription

1 Creation of onrete produts reusing melting slag from waste inineration ash Y Hosokawa*, Kitasato University, Japan Y Ohta, Kitasato University, Japan M Komura, ILB Co Ltd, Japan K Sugawara, ILB Co Ltd, Japan S Muramatsu, Yanagisawa Conrete Industry Ltd, Japan 26th Conferene on OUR WORLD IN CONCRETE & STRUCTURES: August 21, Singapore Artile Online Id: The online version of this artile an be found at: This artile is brought to you with the support of Singapore Conrete Institute All Rights reserved for CI Premier PTE LTD You are not Allowed to re distribute or re sale the artile in any format without written approval of CI Premier PTE LTD Visit Our Website for more information

2 26 th Conferene on Our World in Conrete & Strutures: August 21, Singapore Creation of onrete produts reusing melting slag from waste inineration ash Y Hosokawa*, Kitasato University, Japan Y Ohta, Kitasato University, Japan M Komura, ILB Co Ltd, Japan K Sugawara, ILB Co Ltd, Japan S Muramatsu, Yanagisawa Conrete Industry Ltd, Japan Abstrat Melting slag from waste inineration ash an not only ontribute to redue waste quantities remarkably, but also may be reognized as new material. It is important to study the ability to reuse melting slag into onrete produts from the standpoint of environmental preservation. Interloking onrete bloks were made by six mix proportions with 23.8 and % WIC in eah, 5 and 1% melting slag with rushed sand. All of bending strength of them exeeded 5. N/mm2 of the minimum standard and its strength of and 1% slag in 23.8% WIC was 7.2 and 7. N/mm2, respetively. The onrete were mixed with melting slag, blended with rushed sand by,25,5, 5, 75 and 1% for test piees, and by, 5 and 75% for produts. All of their ompressive strength indiated fully over 27 N/mm2 of the designed strength, and the bending failure load of onrete produts exeeded fully 23 kn of the minimum standard. The olor differene on surfaes of onrete between % and 5% slag was very small. Consequently, melting slag from waste an reuse to reate various onrete produts, as new material. Keywords: onrete produt, interloking onrete blok, melting slag, new onrete material, reuse, waste inineration ash, 1. Introdution The disposal of inineration ash from muniipal waste is one of serious soial problems in and near the large ities and towns of Japan, beause, at present, the landfill site for their disposal beame very narrow and has the limited life. Citizens in their areas an now understand "3R: reyle, redue and reuse", as manners of waste treatment rather than before. As the tehnique to melt muniipal waste diretly as ash gas is developed in Japan, melting waste inineration ash is one of the tehniques to extend the life of landfill site, beause of reduing its quantities remarkably. Some inineration plants of muniipal waste manufature the melting slag by melting waste inineration ash at above 12-entigrade degrees, disappearing wiked gas to ause dioxin pollution. The way to reuse melting slag as onstrution materials is to fill into the sub-base ourse in the pavement onstrution [1, 2] and to mix into onrete [3, 4, 5]. From the standpoint of environmental preservation, it is very important to reate various onrete produts newly by reusing melting slag as new onrete material. Melting slag, however, ontains heavy metal and indiates 325

3 blak olor beause of manufaturing from waste inineration ash. inspet their hemial and physial properties before reuse. Therefore, it is neessary to 2. Materials and Methods 2.1 Properties of melting slag Melting Slag manufatured in the West-Omiya Environment Center of Omiya ity beside Tokyo was mixed into experimental onrete produts, i.e. interloking onrete blok for the pavement, and onrete test piees and produts in the general publi works. The inineration ash (base ash) after burning muniipal waste in the furnae is firstly stoked in the overed yard, and then arried to another furnae to manufature melting slag for quantity redution. When hot raw slag melted in the furnae is dropped into the water pool to quenh, melting slag has many irregular sizes and needles. away. Espeially, the needle is dangerous to treat and needs to wear To reuse as fine aggregate of onrete material, melting slag, as shown in Fig. 1, must be proessed in the milling and rushing equipment while taking away metal of slag and sieving by 5 mm mesh. Melting slag, however, indiates blak olor, and then they worry about the outside landsape of onrete produts beome darker. Furthermore, in Fig. 2, melting slag ontains no alkali-aggregate beause its mortar bar's expansion rate was.21%, smaller than.1% after 24 weeks in the alkali-aggregate reation test. In the hemial omposition of melting slag, shown in Table 1, Si2 and CaO aount for about 4% and 2% of them, respetively. Its quality indiates like a glass, and its CIS, means that (CaO+AI2 3+MgO)/(Si2) indiates a basiity, is.9, smaller than 1.4, whih slag an harden itself after adding water. by adding water. Consequently, this melting slag does not have the harateristi to harden itself Melting slag ontains several heavy metals like Cd, Pb, Cr 6 + and so on, and the leahing value from heavy metals must be inspeted rigidly in Japan. Table 2 shows the results of heavy metal leahing test. melting slag was satisfied the environment standard. Every heavy metal leahing from In Japan, it is very important for heavy metal leahing into water or soil to keep the regulations established by the Environment Ageny in 1991, and also the newest regulation for reuse Fig. 1. Photograph of melting slag..4.3 :: o iii :: u Co x W Fig o Ages (weeks) Result of alkali-aggregate* reation test. * No alkali-aggregate <.1% of expansion rate. Table 1. Chemial omposition of melting slag. Chemial omposition (%) * (CaO+Ab3+MgO)/(Si2) indiates a basi ratio. 326

4 Table 2. Results of heavy metal leahing test of raw melting slag. (Unit: mg/l, exept for ph) Item ph range Cd Pb Cr 6 + As Hg Se Measured value <.1.8 <.4 <.5 <.5 <.2 Regulation* ;;:;;.1 ;;:;;.1 ;;:;;.5 ;;:;;.1 ;;:;;.5 ;;:;;.1 * Regulation for reuse of the melting slag by the Ministry of Welfare in Japan. of the melting slag, established in Otober 1999 by the Ministry of Welfare. atually almost same ontents. problem for onrete material. Both regulations have Thus, it was onfirmed the melting slag without the hemial 2.2 Experiment of interloking onrete blok reusing melting slag The physial properties of fine and oarse aggregate for onrete in this experiment are shown in Table 3. Melting slag has better properties, being good for onrete material with 2.61 speifi gravity,.43% water absorption, and heavier unit density 177 kg/m 3, exepting for fineness modulus of 2.25, being smaller size as fine aggregate. Table 4 shows the onrete mix proportion of six types: two kinds of unit water in normal of 95 kg/m 3 unit water and in adding 11-16% water in eah, 5 and 1% melting slag blended with rushed sand in a volume. The interloking onrete bloks were manufatured by mixing onrete with m slump in the plant, by filling the onrete into the molds, and by vibrating using the strong press mahine. Then the bloks were ured in the uring room with 2-entigrade degrees for oneday and then ured in the stok room with same temperature until the test. The rate of ramming into blok and the hanging rate of blok's shape, by taking bloks outside measurements and weights, were also measured at 7-day age. The bending strengths were measured at 7- and 28-day ages. Table 3. Physial properties of fine and oarse aggregate for onrete. Speifi Water Absorption Fineness Unit density Aggregate gravity (%) modulus (kg/m 3 ) Crushed sand Fine aggregate Melting slag Coarse aggregate Crushed stone* " Maximum gravel size: 1mm, Table 4. Mix proportion of onrete. Item (Blending slag W/C Unit ontent (kg/m3} in a volume) (%) Water Cement Sand Melting slag Gravel Admix. % melting slag % melting slag % melting slag Experiment of onrete produts reusing melting slag The physial properties of fine and oarse aggregate for onrete in this experiment are shown in Table 5. This melting slag with speifi gravity (SG) of and fineness modulus (FM) of was different from the slag with 2.61 SG and 2.25 FM in the former experiment, beause the manufatured period was different in spite of the same environment enter. Table 6 shows the mix proportion of onrete in five types for test piees with, 25, 5, 75 and 1% 327

5 blending melting slag in a volume, and three types for onrete produts with, 5 and 75% slag. The test piees onrete had 5 m slump and 5% air ontent. The ylindrial test piees of f> 1x2 m were for the ompressive strength and 1 Ox1 Ox4 m retangular test piees for freezethaw test by JSCE standard (the temperature of test piee's enter hanges from -18 to 5-entigrade degrees for about four hours per yle in water). The onrete bleeding ratio in fresh onrete and the onrete drying shrinkage in hardening onrete were measured. The ompressive strength was tested at 14-day age and the freeze-thaw test was started at 14 days to 3 yles, measuring the weight and dynami modulus of elastiity of test piees in eah 3 yles. Then, the durability fator was alulated after the freeze-thaw test. The onrete produts were manufatured by fresh onrete with 7 m slump and 1 % air ontent, by filling them into the molds and by vibrating them on the table. Test piees of f> 1x2 m ylinder were for the ompressive test, and the urb bloks for the bending test, and then the drain gutter for the olor differene measurement. Then both onrete produts were ured by steam at the top temperature of 6-65 entigrade degrees for about two hours, and then ured in the normal temperature in the stok room until the test. Furthermore, the olor differene, i.e. olor hroma (C*) and olor value (light, L *), was measured on about 5 points on the surfaes of test piees and onrete produts by using the Chroma Meter CR-2 (MINOLTA Co., Ltd.). Table 5. Physial properties of fine and oarse aggregate. Speifi Water Fineness Unit density Item Aggregate gravity: absorq.{%) modulus {kg/m3) Crushed sand Fine aggregate Test piees Melting slag Coarse aggregate Crushed stone* Crushed sand ** 2.8 Fine aggregate Produts Melting slag Coarse aggregate Crushed stone* * Maximum gravel size: 2mm, ** No data Table 6. Mix QroQortion of onrete. Item & mark Blending Unit ontent * (kg/m WIC sla ) slag (%) (%) Melting Crushed Crushed (vol %) Water Cement slag sand stone A B Test C piees D E F Produts G H * Chemial admixture: air entraining and water reduing agent, and air entraining agent was mixed.5% and.6% of unit ontent of ement for test piees, respetively, and water reduing agent was.1 % for produts. 3. Results and Disussion 3.1 Interloking onrete blok reusing melting slag Fig. 3 shows the relationship between the blending rate of melting slag and the hanging rate of blok's shape. The hanging rate of blok's shape distributes the range between.31 % and.45% and very small without problem. However, the hanging rate beame bigger as the blending rate of melting slag was higher, and WIC in the onrete was slightly bigger in ase of 1% slag. 328

6 The relationship between the rate of ramming into blok and the bending strength at 7 days are shown in Fig. 4. Cramming onrete into the mold by vibrating the press mahine in the manufaturing proess influenes the interloking blok's strength. The rate of ramming onrete of 23.8% and 27.5% W/C in 5%-melting slag bloks was 91.8% and 95.9%, respetively. Thus, as the rate of ramming onrete inreases by adding a little water, to make W/C slightly larger in the onrete, and the bending strength inreases ertainly, beause the onrete with slightly larger W/C in O-m slump beomes fluid to be rammed. Furthermore, Fig. 5 shows the omparison of bending strength of interloking onrete bloks reused, 5 and 1% melting slag. All of the bending strength was onsiderably over 5. N/mm 2, the minimum bending strength standard reommended by the Interloking Conrete Blok Assoiation of Japan. In ase of 23.8% W/C, the differene among the bending strength of interloking onrete bloks of, 5 and 1% melting slag was very small, and the bending strength beame very slightly lower as the blending rate of melting slag inreased from % to 1%. There is a small influene of the blending rate of melting slag in the bending strength. In ase of 1% melting slag, both bending strength of 23.8 and 26.3% W/C were almost equal, but the strength of the latter indiated 7.2 N/mm 2, a little larger than the former of 7. N/mm 2. Thus, it is proved the interloking onrete bloks an be mixed up to 1% melting slag, by few unit water quantity and smaller W/C like % with m slump. However, the lifeyle of interloking onrete bloks reusing 1% melting slag must be studied later..5 (]) Q..4 C/) C/) ::,.: g.3 :n '.2 (]) -ttl... OJ.1 OJ. t) Fig J * A 23.8* * * * Numeral in figure: W/C (%) o 5 1 Blending rate of melting slag (%) Relationship between blending rate of melting slag and hanging rate of blok's shape. N E 8 E 7 -z...- : > 6 (])... -C/) OJ '6 (]) (Xl _2.7.5* ---2"1;5-"" ?:? : ,.:----%sla9-- 6, A: 5% slag ,.-:--1 %- -Slag---- * Numeral in figure: W/y (%) Rate of ramming into blok (%) Fig. 4. Relationship between rate of ramming onrete and bending strength at 7 days N W/C:.23.8% m27.5% % E E 8 -z - : 6 -OJ C 4 -C/) OJ '6 (]) (Xl Fig % 5% 1% Blending rate of melting slag Comparison of bending strength of interloking onrete bloks reused, 5 and 1% melting slag at 28 days. 329

7 3.2 Conrete produt reusing of melting slag As shown in Fig. 6, the onrete drying shrinkage indiated.7-.6%, being a half generally, after 24 weeks, and beame bigger as the blending rate of melting slag beame larger, similarly as the onrete bleeding beame larger in Fig. 1. The omparison of ompressive strength of test piees for onrete produts is shown in Fig. 7. All of ompressive strength of test piees exeeded fully the designed one of 27 N/mm 2. The ompressive strength of test piees obviously had smaller, as the blending rate of melting slag beame larger, but the test piees of produts did not have a same tendeny. From the results of ompressive strength, the reasonable blending rate of melting slag may be up to 5% in the test piees, but it will be up to 75% in the produts within this experiment.,... ::R... x Q) -4 ::.;:: -B Ol ::.Eo -8. OA o B --- o f). E o Ages (weeks) Fig. 6. Changes of onrete drying shrinkage..s::: g> (J) - 3 (1)1:. E Z 2 (1)..... E 1 o Blending rate of slag (%) Fig. 7. BCD E F G H Comparison of ompressive strength of onrete test piees (A-E) and produts (F-H). Then, Fig. 8 shows the omparison of bending failure load of onrete produts of urb blok. Although the standard bending failure load is 23 kn by JIS (Japanese Industrial Standard), the bending failure load of urb bloks have bigger in spite of the range of blending rate of melting slag. 75% melting slag onrete had almost twie of the standard bending failure load. From the ompressive strength of test piees (Fig. 7) and the bending failure load of produts (Fig. 8), the important fators in the onrete mix proportion are the smaller W/C and the unit ement quantity. is reommended kg/m 3 of unit ement quantity in % W/C, if mixing up to 75% melting slag with rushed sand. The results of freeze-thaw test are shown in Fig. 9. At 3 yles of freeze-thaw test, all of onrete indiated more than 6% of relative dynami modulus of elastiity (Ed), and in general they have the freeze-thaw durability. However, the onrete test piees of 75 and 1% melting slag had about 2% weight loss and indiated below 9% of relative Ed, being different from the onrete of, 25 and 5% of them. In the onrete durability, it is reommended up to 5% melting slag. Fig. 1 shows the relationship between the onrete bleeding ratio and the durability fator. It As inreasing the blending rate of melting slag, the onrete bleeding ratio inreased but the durability fator dereased. The onrete was separately divided A-C (-5% melting slag), D (75%) and E (1%) groups by the bleeding ratio, and A-C and D-E groups by the durability fator, statistially (p<.5). Thus, the onrete bleeding influenes the onrete durability. reommended up to 5%, as same as in Fig. 9. The blending rate of melting slag is Fig. 11 shows the distribution of olor quality on surfae of onrete test piees and produts like drain gutter. The olor hroma (C*) has a range from (grayish) to 6 (vivid), and the olor value (light: L*) also from (dark) to 1 (light). The olor hroma orrelated losely with olor 33

8 value in the onrete test piees (p<o. 1), and as inreasing the blending rate of melting slag, the onrete fae beame darker, but its differene was very small ompared with the olor quality range. Consequently, the onrete produts with % WIC and kg/m 3 unit ement quantity an reuse up to 5% melting slag with rushed sand. produts mixed the melting slag need the mark "Slag Inside" on the surfae. Z "" C\l.Q 5 4.Q 3.d -1 To distinguish the normal produts, the onrete 1:"#..2> -... 'ro 2 1 fiiefej:e > C ' "" en Fig :;:; 2. C\l '- > 1.5 "" : '- ().5 F [JIS] G H Comparison of bending failure load of onrete produts. 8 '- t) C\l 6;" :t:: 4 :g '- ::J Cl 2 S (/) (/) 2 1 W 8 > 7 Q) :: 6 o ' Ql...J i -...J. - A, B, C D, L,. E * Ed: Dynami modulus of elastiity Freeze-thaw yles Fig. 9. Results of freeze-thaw test. 1: 6 I l : : E' > :.:::i t 5 r : :- ---r-= O.:966*--,,, '-. 5 1> slag prdut,, '- C\l 4 Cl Relationship between onrete bleeding Color (C*) ratio and durability fator (OF). Fig. 11. Distribution of olor quality on * Columns with different letters, a and b, or x, y and z, surfaes of test piees and produts. indiate signifiant differene at 5% level, respetively. 8 7 r,,,, A 4. Conlusion Melting inineration ash to redue muniipal waste quantities remarkably is an epoh-making tehnology. The results of experiments onerning with the effetive utilization of melting slag were obtained as following; (1) Melting slag is proessed in the milling and rushing equipment to reuse as fine aggregate of onrete material, and does not ontain alkali-aggregate and heavy metal with the leahing value over the environmental regulation, and then has no harateristi to harden itself by adding water. (2) The physial properties of melting slag have a variation as the speifi gravity extended and the fineness modulus extended , beause the manufatured periods were different in spite of the melting slag manufatured in the same environment enter. (3) The interloking onrete bloks were made by mixing, 5 and 1% melting slag with 331

9 rushed sand in a volume. All of the bending strength was onsiderably over 5. N/mm2 of the minimum standard, and its strength of and 1% slag blok of 23.8% WIC indiated 7.2 and 7. N/mm2, respetively. The strength beame very slightly lower as the blending rate of melting slag inreased up to 1%. The interloking onrete bloks an be mixed up to 1% melting slag, beause of the m-slump onrete with few unit water quantity and smaller WIC like %. (4) The onrete with 5-7 m slump were mixed by,25,5,75 and 1% melting slag with rushed sand in a volume for test piees, and by, 5 and 75% for produts of urb bloks and drain gutter. All of their ompressive strength exeeded fully 27 N/mm2 of the designed strength, and also the bending failure load of onrete produts exeeded 23 kn of the minimum standard. From the onrete durability influened by the onrete bleeding ratio, it is reommended up to 5% melting slag. Furthermore, as inreasing the blending rate of melting slag, the onrete surfae beame a little darker, but its olor differene was very small. Consequently, melting slag an be reused into onrete produts with % WIC and kg/m 3 unit ement quantity by mixing up to 5% in safety, sometimes 75% with rushed sand. (5) Melting slag from waste an reuse to reate various onrete produts, as new material. Aknowledgement: The information onerning with melting slag manufature were given from Mr. Shun-ihi Saito, the Saitama-City West Environment Center in Saitama Prefeture, and Daido Steel Co., Ltd. One of the experiment was studied in the Conrete Produts Plant by the ooperation of Mr. Kenji Oikawa, Aomori Maeta Conrete Industry Ltd. Furthermore, the students of eo-system onrete laboratory of Kitasato University helped in these experiments. The authors are gratefully aknowledged to them. Referenes: [1] Ihihara, T. Reuse of slag manufatured by melting muniipal waste ininerator residue, Eletri Steel Manufature (Tehnial Report of Daido Steel Co., Ltd.), VoI.68(4), pp (1997). (In Japanese with English abstrat) [2] Kinto, K., H. Goto, T. Ihihara and H. Hirane. Properties and reuse of slag manufatured by melting fly ash and ininerator residue from muniipal waste, Eletri Steel Manufature (Tehnial Report of Daido Steel Co., Ltd.), Vol. 68(4), pp (1997). (In Japanese only) [3] Hiraoka, M., N. Takeda, S. Sakai, T. Tsunemi and M. Komura. Development of permeable interloking bloks using sewage sludge molten slag, Proeedings of 4th International Conferene of Conrete Blok Paving, pp (1992). [4] Kitatsuji M. and K. Fujii. Fundamental studies on the utilization of melting slag from inineration ash from muniipal solid waste as fine aggregate for onrete, Transation of JSIDRE, No. 192, pp.1-8 (1997). (In Japanese with English abstrat) [5] Hosokawa Y, K. Oikawa, T. Kudo, D. Kimura, M. Komura and S. Saito. Charateristis of interloking bloks reusing melting slag manufatured by melting inineration ash of muniipal waste, 14. INTERTNATIONALE BA US TOFF TA GUNG, TAGUNGSBERICHT-Band 2, pp (2). 332