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SAYKEE Enterprise, Inc SAYKEE Enterprise, Inc Presentation Transcript

  • II Congreso Internacional de la Construcción Argos Panamá October 3rd, 2013   Trends in Waste Concrete Recycling in Japan Shinichi SUZUKI EX Research Institute Ltd.
  • Contents 1. Waste Concrete Recycling Trends in Japan 2. Development of Recycled Aggregate Concrete 3. Technology of Recycled Aggregate Concrete 4. Management of Manufacturing Recycled Aggregate Concrete 5. Challenges to the Expansion of the Use of Recycled Aggregate Concrete 6. Conclusion
  • 1. Waste Concrete Recycling Trends in Japan Unit: 10,000 tons Shipping Amount Recycling From Demolition Amount Sites Disposal Amount Recycling Rate 1995 3,650 2,359 1,288 64.6% 2000 2002 3,530 3,394 133 3,510 3,425 87 96.2% 97.6% 2005 3,220 3,155 60 2008 3,130 3,043 84 Source: Ministry of Land, Infrastructure and Transport(MLIT) 98.0% 97.3% 1
  • 1. Waste Concrete Recycling Trends in Japan  Mass balance Unit: million tons Recycled Stones Slag 8.18 from Waste Asphalt 4.05 6% Generation To Discharge Amount Recycling Recycling Recycle Recycled Amount 32.01 31.27 Plant 30.62 30.43 Plant Stones (Crushing) 37.20 29% Usage of On Site Use Crushed Recycled Sand 0.74 Stones, 2.94 Disposal Disposal gravel etc Crushed 0.65 0.19 For Size ControlStones(virgin)65%129.95 5.65 84.57 Disposal Site Source: Ministry of Land, Infrastructure and Transport(MLIT) 2
  • 1.Waste Concrete Recycling Trends in Japan    Current Major Recycling Methods Most waste concrete was used for base course material and back-filling material After finishing the standardization of all three types of recycled aggregate in 2007, the resulting use of recycled aggregate was about 15,000 tons (simple tabulation) according to a survey in 2008. Photos: Takenaka Corporation 3
  • 1.Waste Concrete Recycling Trends in Japan  Waste Concrete Generation in the Future Unit: million m3 Shipping Volume of Ready-Mixed Concrete 1962-1998 150 100 50 Year Source: http://www.kkr.mlit.go.jp/fukusan/topics/h23/kyouboshi.pdf 4
  • 1.Waste Concrete Recycling Trends in Japan      Waste Concrete Generation in the Future The amount of waste concrete generated is predicted to grow. An increase of 4 to 6 times is expected by 2050 due to the lifetime of concrete structures which were built in the past. Reviewing trends in public works budgets, construction of new roads has reduced. Budgets will be allocated more for maintenance, rather than new construction. Crushed stones have been collected by blasting mountains while gravel has been collected from riversides, which has been difficult. Both activities heavily impact the environment. Thus it is important in Japan that waste concrete aggregate is used again and again for recycling. 5
  • 1.Waste Concrete Recycling Trends in Japan Use of Waste Concrete Aggregate has the following two types: (a) Opened-Loop Concrete Recycling System Old building Survey of demolished building Concrete production Test specimens for confirmation of concrete properties Demolition (b) Closed-Loop Concrete Recycling System Manufacture of recycled coarse and fine aggregates 6
  • 2. Development of Recycled Aggregate Concrete  Background • 1973: the building Contractors Society (BCS project) and the Ministry of Construction (1st project) started research 1992: the Synthesis Technical Development Project(2nd project) of the Ministry of Construction started to research a more practical basis for recycled aggregate concrete. 2003: JASS 5 prescribed, based upon the above results, that recycled aggregate may be treated as natural aggregate if it achieves a quality equivalent to gravel and sand. 2005-2007: in 2005 the Japan Industrial Standard (JIS A 5021) for concrete-class H “high-quality recycled aggregate”, in 2006 JIS A 5023 for concrete-class L “low-quality aggregate” , and in 2007 JIS A 5022 for concrete-class M “middle-quality aggregate” were enacted respectively . • • • 7
  • 2. Development of Recycled Aggregate Concrete  Relations Between Recycled Aggregate H,M,L & Recycle Concrete JIS A 5021 Recycled Aggregates H JIS A 5308 Ready-Mixed Concrete Factory JIS A 5308 Ready-Mixed Concrete Natural Aggregates Recycled Aggregates H Recycled Aggregates M JIS A 5023 Ready-Mixed Concrete Factory Which Recycled Aggregate L Purpose-Built JIS A 5023 Recycled Aggregate Concrete L JIS A 5022 Recycled Aggregates M JIS A 5022 Natural Aggregates JIS A 5023 Recycled Aggregates L Natural Aggregates Recycled Aggregates H - Do for M - JIS A 5022 Recycled Aggregate Concrete M Source: Yukikazu Tsuji, “JIS Products of Recycled Concrete (Japanese), 2007 8
  • 2. Development of Recycled Aggregate Concrete  Major Use of Each Type of Recycled Aggregate Concrete H Defined Standard Standard as aggregate M L Standard as concrete Members/elements which are not Application Same as natural affected by drying shrinkage, such as aggregate piles, footing beams, steel tube filled concrete, etc. Members/elements which do not require intensity and durability, such as back filling, leveling concrete, etc. 9
  • 2. Development of Recycled Aggregate Concrete  Standardized Recycled Aggregate Concrete (JIS) Coarse Aggregate H Oven-dry density (g/cm3) Water absorption (%) Fine material content (%) percentage of wear and abrasion resistance (%) M L Crushed Stone for concrete ≥2.5 ≥ 2.3 ー ≥ 2.5 3.0≥ 5.0 ≥ 7.0 ≥ ≥ 3.0 1.0 ≥ 1.5 ≥ 2.0 ≥ 1.0 ≥ 35 ≥ ー ー 40 ≥ 10
  • 2. Development of Recycled Aggregate Concrete  Standardized Recycled Aggregate Concrete (JIS) Fine Aggregate H Oven-dry density ≥ 2.5 (g/cm3) Water absorption 3.5 ≥ (%) Fine material 7.0 ≥ content (%) percentage of wear ー and abrasion resistance (%) M L Crushed Sand for Concrete ≥ 2.2 ー ≥ 2.5 7.0 ≥ 13.0 ≥ 3.0 ≥ 7.0 ≥ 10.0 ≥ 7.0 ≥ ー ー ー 11
  • 3. Technology of Recycled Aggregate Concrete  Two Basic Production-Method Concepts Aggregate Refining Method Aggregate Replacing Method Removing the original Reducing the influence of the mortar contained in the original mortar and producing Basic recycled aggregate to concrete with the required Idea acquire quality equivalent performance capability by mixing to natural aggregate such natural aggregate and recycled as gravel and sand, and aggregate at the concrete being used as a substitute manufacturing stage E.g. Office buildings, Apartment House, etc Biotope Soga symbiosis building, Incinerator building in Yokohama 12
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (Outline) Screening Method Crude Concrete after Demolition Crushing Method Rubbing Method H Jaw crushers Primarily Crushed Materials Primarily Treatment Source: Japan Society of Civil Engineers Wet Screening Heating and Rubbing Method Others (Coating Method) Secondary Treatment 13
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (Outline) (1) Crushing Recycled Sand        Crude Concrete Concrete Lump Crude Concrete Screening Apparatus Impact crushers (horizontal axis type) Dust removal Screening Apparatus Recycled Gravel Jaw crushers Recycled Roadbed Materials Water Washing Rod Mill Source: Japan Society of Civil Engineers Screening Apparatus 14
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (1) Crushing Method        Recycled coarse aggregates Crushing Method (Grade M or L) Recycled fine aggregates Rubbing Method (Grade H) Source: Kyoboshi Corporation 15
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (2) Rubbing Method: Mechanical Grinding If treated more than once Concrete Lump Lump Concrete Lump Concrete Screen Apparatus eccentric-shaft rotor device 70% Screen Apparatus Jaw crusher Rejected Coarse Aggregates Source: Japan Society of Civil Engineers(partially added) 30% 16
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (2) Rubbing Method: Mechanical Grinding The eccentric-shaft rotor device   Crushed concrete Under 50mm Vibrating sieve Processing system with the eccentric-shaft rotor device   Source: Takenaka Corporation The eccentric-shaft rotor device   17
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (2) Rubbing Method: Mechanical Grinding Actual Application Example Old office building 7-stories Concrete lump: 10,000t Whole quantity: 80,000t Source: Takenaka Corporation New office building 38-stories Recycled coarse aggregate: 3,000 t Recycled concrete volume: 5,000 m3 18 Used as BF-1F slab
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (3) Gravity Concentration by Wet Screening Method 10% Fine Powder Concrete Lump Concrete Lump Screen 2% Impact crushers Rubbing Apparatus Screen Wet Screen Rejected Jaw crusher 15% 45% 28% Rubbing Apparatus Back-filling Materials,etc Recycled Fine Aggregate Source: Japan Society of Civil Engineers(partially added) Light Recycled Materials Aggregates 19
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (3) Gravity Concentration by Wet Screening Method Photos: Kyoboshi Corporation 20
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (3) Gravity Concentration by Wet Screening Method Recycled Aggregate Low density area Surface Water Lever High density area Low Density Recycled Aggregate High Density Recycled Aggregate Source: Kyoboshi Corporation 21
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (4)Heating and Rubbing Method Recycled coarse aggregate Heating treatment Rubbing treatment Recycled fine aggregate Disintegration of cement paste by dehydration Selective separation of cement paste Source: Mitsubishi Materials Powder 22
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (4)Heating and Rubbing Method 44% Concrete Lump Concrete Lump Fine Powder Coarse aggregate recovering equipment (Ball Mill) Jaw crusher Fine aggregate recovering equipment (Secondary Mill) Screen Packed bed heater (300℃ ) Fine Aggregate Coarse Aggregate Source: Japan Society of Civil Engineers(partially added) 21% 35% 23
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (4) Heating and Rubbing Method Whole View of the Aggregate Recycling Plant Source: Shimizu Corporation 24
  • 3. Technology of Recycled Aggregate Concrete 3.1 Aggregate Refining Method (1)Effect of Recycling The recycling rate of “Heating and rubbing” and “Mechanical grinding” are reported to be as high as about 56% and about 30% respectively. However, the recycling manufacturers use byproducts of recycled aggregate such as fine powders for their other businesses such as the manufacture of roadbed materials. Thus it is believed that the recycling rate of the recycling manufactures are more than 95%, otherwise their recycling business can not be continued. 25
  • 3. Technology of Recycled Aggregate Concrete (2)Unit Price According to a survey by ACRAC of its members in 2011, the average unit price by spot delivery is as follows. Type Coarse Aggregate Fine Aggregate L $10.9/t $7.9/t M $12.0/t $17.5/t H $22.0/t $25.0/t (3) CO2 Emission The CO2 emissions from recovering recycled aggregate are high, yet total emissions can be reduced. 26
  • 3. Technology of Recycled Aggregate Concrete 3.2 Aggregate Replacing Method (1) Outline Crushed 200m3 (2002) Recycled concrete manufacturing concrete Demolition 1,000m3 (2005) 600m3 (2008) 11,00m3 (2009-2010) Precast concrete product Recycled roadbed gravel 27-45% Mixed with natural spray concrete aggregate which is replaced Approved by MLIT as structural 55-73% Block type concrete Source: Y.Dosho, “Development of a Sustainable Concrete Waste Recycling System laying member 27 http://www.aij.or.jp/jpn/design/2013/date/32_2013award_dohshoY_dtd.pdf
  • 3. Technology of Recycled Aggregate Concrete 3.2 Aggregate Replacing Method (2)Blending Planning   Method that decides the mixing ratio of natural aggregate to recycled aggregate to assure the performance of concrete The value of relative quality is an index used for assessing aggregate quality and is given by the following equation. QCt= QCvG x a + QCvS x b + QCrG x c + QCrS x d a+b+c+d Where; QCt(%): Relative absorption rate; QCvG(%): Absorption rate of natural coarse aggregates in recycled aggregate concrete QCvS(%): Absorption rate of natural fine aggregates in recycled aggregate concrete QCrG(%): Absorption rate of recycled coarse aggregates in recycled aggregate concrete QCrS(%): Absorption rate of recycled fine aggregates in recycled aggregate concrete A,b,c,d(L/m3): Absolute volume of natural coarse aggregate, natural fine aggregate, recycled coarse aggregate, and recycled fine aggregate, respectively 28
  • 3. Technology of Recycled Aggregate Concrete 3.2 Aggregate Replacing Method (1) Effect of Recycling A simulation was carried out by TEPCO based upon a case study in which a current thermal power plant (350,000kW) is to be replaced with a 1.5MW facility.  The amount of waste concrete generated would be about 9,700m3, all of which could be confirmed for use at the present site as recycled aggregate concrete (about 11,000m3) and recycled crushed stones (about 6,500m3). (2)Cost Relative to the current use for back-filling and roadbed materials, the cost would be reduced by about 41% because of savings in waste disposal fees and in material for aggregate and crushed stones. 29
  • 4. Management of Manufacturing Recycled Aggregate   Concrete (1) Receiving Inspection   A. Reaction rims surrounding aggregate and/or cracks in the aggregate must not be observed. B. Fractured surfaces of aggregate must not be covered with crystallined materials, nor colored white. C. On the surface of concrete, white deposits must not be observed. Source: Kyoboshi Corporation 30
  • 4. Management of Manufacturing Recycled Aggregate   Concrete (2)Product Inspection   A. Monthly chemical analysis is conducted based upon the JIS A 5308 appendix 7. B. The Fresh-Con GBRC Rapid Method* is conducted with lot inspection time. *Test for alkali-aggregate reactivity of ready-mixed concrete (3) Implementation of control measures to total alkali •The amount of the total alkali of recycled aggregate concrete is not more than 3.0kg/m3 even though the recycle aggregate is judged as harmless. Source: Kyoboshi Corporation 31
  • 4. Management of Manufacturing Recycled Aggregate   Concrete  Quality Control (On-site for refining method) Investigation of structure to be demolished and aggregate used in the structure Quality control of concrete lump; mainly impurity Processing for recycling Inspection of the quality of recycled aggregate Quality control of recycled aggregate Manufacturing of concrete using recycled aggregate Inspection of concrete using recycled aggregate Source: Takenaka Corporation Check Items Alkali-Aggregate Reaction (AAR) * *if necessary Impurity Density, Water absorption, Grading curves, Chlorides content, Impurity Slump and flow Compressive strength AAR* 32
  •  4. Management of Manufacturing Recycled Aggregate   Concrete Quality Control (On-site for replacing method) Demolition Physical & Chemical Survey conformity Recycled Aggregate Production Quality Survey conformity Blending Planning nonconformity nonconformity Re-inspection or Disabled Recycled Aggregate Concrete Production Quality Survey conformity Apply nonconformity Source:http://www.aij.or.jp/jpn/design/2013/date/32_2013award_dohshoY_dtd.pdf 33
  • 4. Management of Manufacturing Recycled Aggregate   Concrete  Quality Control (On-site for replacing method) Survey Checked Items Intensity of original concrete, chloride Physical & chemical survey content, alkali-silica reaction, with or on original concrete which without deterioration symptoms is planned to be demolished Quality control/inspection ofMajor physical property of aggregate, manufactured recycled amount of impurity, alkali-silica aggregate reaction, chloride content Quality control/inspection of Slump, air capacity, chloride content, alkali-silica reaction, intensity manufactured recycled aggregate concrete Source:http://www.aij.or.jp/jpn/design/2013/date/32_2013award_dohshoY_dtd.pdf 34
  • 5. Challenges to the Expansion of the Use of Recycled Aggregate Concrete     The “Law on Promoting Green Purchasing” has been amended, but recycled aggregate is only on the longlist. Why? - Is it possible to procure all over the country? - Can its durability be guaranteed? It is not included in government project specifications. (but the Tokyo metropolitan government has changed after it was selected as the Olympic host) Not enough capacity in urban areas High costs, esp. when demolition site is 40 km+ away 35
  • 5. Challenges to the Expansion of the Use of Recycled Aggregate Concrete  The case of non-conforming melt slag aggregate used for concrete in 2007-2008    A registered concrete manufacturer, namely Mutuai Concrete Ltd., used non-conforming melt slag as recycled aggregate. “Pop-out” phenomena were observed in the constructed concrete due to quicklime contained in melt slag. This case emphasized that recycled aggregate, when applied to concrete, should be used with caution. 36
  • 5. Challenges to the Expansion of the Use of Recycled Aggregate Concrete  Association The Affairs Council of Recycled-Aggregate Concrete (ACRAC) is formed by voluntary recycling manufacturers who aim to include recycled aggregate concrete in their project specifications. As of 2013 there are 19 firms participating in ACRAC. ACRAC takes responsibility for its own products. Source: ACRAC grade grade grade 37
  • 6. Conclusion    Almost 40 years have past since recycled aggregate concrete was first studied in Japan. JIS was enacted for recycled aggregate, and stable manufacturing technologies have been established. Based upon the portion of civil engineering and construction that uses concrete, the quality requirements of concrete will change. It is necessary to secure a suitable balance regarding 1) safety and quality, 2) cost and effectiveness, and 3) environment impact. There are two approaches to using recycled aggregate; (a) the refining aggregate method, and (b) the replacing aggregate method. There are merits and demerits of both methods. 38
  • 6. Conclusion     In the case of (b), applicable sites will be mostly limited to massive building projects which have a record of using aggregate and concrete, such as power plants. Both methods require inspection for the purpose of manufacturing safe concrete. It is important to prevent recycled aggregate-manufactured devices from being delivered in inappropriate concrete lumps, especially in the case of (a). To increase recycled aggregate concrete use, the role of government is very important: to standardize recycled aggregate, promote green procurement, and punish companies who break the law. For the success of recycled aggregate business, the discarded byproducts should be minimized as much as possible by excluding impurity at the beginning of recycling, 39 and by utilizing byproducts obtaining social credibility.
  • 6. Conclusion  Waste concrete recycling is inevitable because of the increasing use of concrete, especially after WWⅡ - a trend which will discontinue in the near future. There is lots of know-how regarding waste concrete recycling in Japan, so we can share our experience. 40
  • Thank you very much suzuki@exri.co.jp