○○○○○○○ High quality recycled aggregate One approach to its production technology from the view points of Development concept & Performance analysis １

Index 1. Investigation on quality of traditional recycled aggregate(=>non processed recycled aggregate). 2. Quality of recycled aggregate after quality improvement process. (=>processed recycled aggregate by VSI 3. Assessment of the quality of concrete to use processed recycled aggregate.(Through test in being compared with natural aggregate and non processed aggregate. 4. Development concept of Kemco RC7 =High quality recycled aggregate production system= ２

Background ・ A lot of demolition concrete are daily generated by demolition works of old concrete buildings. ・ More than 90% of demolition concrete is currently used for lower grade application including sub base or sub layer. ・ It is foreseen that the demand for these lower grade application cannot absorb increasing volume of demolition concrete to keep on increasing. The production of high quality recycled aggregate for the use of concrete for construction is highly required. ３

1.Investigation on quality of traditional recycled aggregate(=>non processed recycled aggregate.) 1) Traditional recycled aggregate: Demolition concrete is crushed by crusher and foreign objects include metal and wood etc. are eliminated by magnetic and/or air separator. It was traditionally and is currently used as coarse aggregate with size range of 40- 0mm or 30-0mm. 2) Its quality The property of traditional aggregate has a lot of unknown factors and its quality widely varies. （ Field investigation of its quality) a) Sample collection: The coarse and fine samples were collected at a demolition concrete processing plant every two weeks for 1 year. b) The points to be investigated: I)Density, II)Water absorption, III)40tf crushing value （ BS 812 ） and IV)cement paste content. ４

Property of non processed recycled coarse aggregate Density(Oven dry) Water absorption ・ Non processed recycled coarse aggregate g/cm 3 5-8% ・ Its original property g/cm % =Density is in reverse proportion to water absorption as shown on the above blue single direct line.= Density (g/cm 3 ) Water absorption ( ％） Non processed recycle aggregate Crushed stone Original property of non Processed aggregate ・ Lower density ・ Higher water absorption ・ Higher density ・ Lower water absorption ５ Lowe quality Fickleness Higher quality Stability

Cement paste  Density Non processed recycled coarse aggregate (Nitric acid with 25% of concentration was used for dissolving cement paste) ・ Un removed cement paste varies from 25% up to 54%. ・ The more cement paste, the less density. The less density is caused by cement paste Un removed cement paste （％） Density (g/cm 3 ) The more cement paste, the less density ６

Cement paste  40tf Crushing value(BS 812) 1) Traditional recycled aggregate =>20-28%, 2)The regular crushed aggregate=>14.5% 1) Few co-relation between cement paste & 40th crushing value was found. 2) It is presumed that there is certain co-relation between cement paste and W/C ratio Un removed cement past （％） 40tf crushing value （％） ７ (To harden three layered samples by pressing each layer 25 times by using a rod. And to give 398kN of load on the sample for 10 minutes and measure the volume of -2.5mm content. ・・・・・・ BS812 ）

Property of non processed recycled fine aggregate Density(oven dry) Water absorption ・ Non processed recycled fine aggregate g/cm % At the time of crushing of demolition concrete, its fragile part with low density and porous property generates a lot of micro fine. The lower quality is caused by this micro fine. ・ Natural/Crushed fine aggregate g/cm 3 2-3% ・ =Density is in reverse proportion to water absorption as shown on the above blue single direct line.= Density (g/cm 3 ) Water absorption （％） Traditional recycled concrete Natural sand Crushed sand ８ ・ Lower density ・ Higher water absorption Lower quality Fickleness ・ Higher density ・ Lower water absorption Higher quality Stability

Quality of non processed recycled aggregate. =Summary= 1) Non processed recycled coarse aggregate: a) Cement paste : 25-54% b) Density(oven dry) : g/cm 3 c) Water absorption : 5-8% d) 40t/f crushing value:20-28% = This quality is inferior to that of natural material crushed aggregate= 2) Non processed recycled fine aggregate: a) Density(oven dry) : g/cm 3 c) Water absorption : % = This quality is inferior to the above 1) and widely varies. 3) Conclusion: =The more cement paste, the less density.= The less density is caused by cement paste. Quality improvement can be attained by removing cement paste. ９

2.Quality of recycled aggregate after quality improvement process(processed recycled aggregate). 1) Quality improvement process(How to remove cement paste): a) The material passes through Vertical Shaft Impactor (Barmac Hustler) up to 5 times(max.). This VSI has easy operation, high performance and low energy consumption. b) Micro fine with less than 1.75g/cm 3 of density which is produced after 5 passes and composes 10% of 5-0mm is eliminated by specially designed air separator. * The advantage of VSI “Rock on rock” crushing system is a feature and it is good at shaping the material. As “Rock on rock” crushes the fragile part of material, it helps to remove cement paste very much for improving quality. 2) Property of a random sample: a) Size : 30-13mm b) Density(oven dry) : 2.25g/cm 3 c) Water absorption : 6.45% １０１０

Number of “Passes”  Removal of cement paste for coarse aggregate ・ 3 passes remove 70% of cement paste. ・ 5 passes remove 80% of cement paste. ・ After 4 passes, cement paste cannot be further removed remarkably Pass times Un removed cement past （％） 70% removed80% removed Easy and effective way of removal. １ 9% 14% 42%

・ 3 passes can attain more than 2.5g/cm3 of density and less than 3 %of water absorption. => “H” grade of JIS ・ To become equivalent to its original property after 5 passes Original property Numbers of passes Density (g/cm 3 ) Water absorption( ％） DensityWater absorption “ Ｈ ”grade of JIS 3 passes attain “H” grade １２１２ Easy and effective way of quality improvement. Number of “Passes”  Density and Water absorption For coarse aggregate

・ In the zone where more than 20% of un removed cement paste is still remained, density of its cement paste is approx.2.15g/cm 3 ・ In case of less than 15%, its density drastically gets higher Un removed cement past （％） Density of un removed cement past(calculated)( ％） Higher density few negative affect on concrete Density gets higher Lower density In the zone where un removed cement paste is less than 10%, density of cement paste is more than 2.5g/cm 3. It is high density and its negative affect on quality of concrete is regarded as negligible small. １３１３ （モルタル付着率と原骨材密度と再生粗骨材密度よりの付着モルタル密度計算 値） Density of un-removed cement paste in its each volume:

・ “40ft crushing value” drops drastically through 3 passes, however thereafter, there is no remarkable improvement Original aggregate Crushed stone Pass times 40tf crushing value （％） Drastic drop Gets stable １４１４ Number of “Passes”  “40ft crushing value (BS812)

・ Density of natural sand is stable in each particle size range. ・ Density of non processed recycle aggregate is relatively low, especially in finer particle size range. ・ 3 passes shows lower density in the size range of under 0.3mm. The particle with lower density is to be eliminated by air separator ～ ～ ～ ～ ～ ～ 0 Size (mm) Density (g/cm 3 ) Natural sand ３ passes No processed １５１５ Density by each particle size range under 5mm For fine aggregate

・ While 3 passes with air classification is still inferior to natural sand, its quality has been very much improved if it is compared with non processed sand Natural sand ３ pass 3 passes with air classification Sand Density (g/cm 3 ) Water absorption （％） DensityWater absorption Improvement of density & water absorption １６１６ Comparison of “density” and “water absorption” in 4 different types of fine aggregate. Non processed

Quality of processed recycled aggregate =Summary= Quality improvement by VSI 1) Coarse aggregate a) 70% and 80% of cement paste were removed after 3 passes and 4 passes respectively. b) More than 2.5g/cm 3 of density and less than 3% of water absorption were attained after 3 passes. These figures comply with “H” grade of JIS requirement. 2) Less than 10% of cement paste has very high density and its negative affect on quality of concrete is regarded as negligible small. 3) Fine aggregate: After 3 passes and elimination of less than 0.3mm of micro fine, a great deal of quality improvement was attained. ・ The more passes, the better quality by VSI ・ The quality becomes equivalent to the natural aggregate after 3 passes. ・ High efficiency and easy operation and maintenance. １７１７

3. Assessment of the quality of concrete to use processed recycled aggregate: (Through tests in being compared with natural aggregate and non processed aggregate) 1) Test items: a) Strength(Compression strength/Tensile strength) b) Dry shrinkage c) Durability (Freezing and thawing ， Neutralization ） 2) Sample materials: a) Natural aggregate. b) Non processed recycled aggregate. c) Recycled aggregate after 3 passes by VSI. d) Recycled aggregate after 5 passes by VSI. １８１８

W/C ratio  Compression strength for 4 coarse samples ・ W/C ratio and compression strength for each sample are in the proportionate relation as shown on the above lines. ・ The strength of 3 passed sample gets equivalent to that of natural aggregate. ・ The strength of non processed aggregate remarkably gets lower than those of 3 others especially in higher strength zone. (7 days result) (28days result) Cement water ratio Compression strength （ N ／ mm 2 ) Natural Non process ３ pass ５ pass Cement water ratio Compression strength （ N ／ mm 2 ) Natural ３ pass ５ pass １９１９ Non process

W/C ratio  Compression strength for 4 fine samples ・ Concrete to use processed fine sample with 10% of fly ash added could attain equivalent to or better compression strength than that of natural sand regardless W/C ratio and aging of sample. ・ Compression strength in case of non processed sample is getting lower especially in higher W/C ratio zone Cement water ratio Compression strength （ N ／ mm 2 ) Natural Non processed Processed Processed wit fly ash Cement water ratio Compression strength （ N ／ mm 2 ) ２０２０ (7 days result) (28days result) Natural Non processed Processed Processed wit fly ash

Dry shrinkage for 3 fine samples ・ The dry shrinkage of 3 passed sample is equivalent to that of crushed sand. ・ Non processed aggregate has 2.2 times higher dry shrinkage than crushed sand Age of concrete （ day ） Drying shrinkage （ ×10 -6 ） Natural Non processed ３ pass ２. ２ times ２１２１

Dynamic modules of elasticity of concrete for 5 fine samples ・ Dynamic modulus of elasticity of concrete to use 3 passed fine sample with or without natural sand is equivalent to that of crushed sand even after repeating freezing and melting tests 300 times. ・ The concrete to use non processed fine sample dropped by approx. 50% after 300 times of freezing and melting test if it is compared with crushed and and processed samples. ・ The concrete to use non processed coarse and fine sample dropped down to 40% after 120 times of freezing and melting test. Thereafter, no data was obtained Cycle of freezing thawing （ times ） Dynamic modulus of elasticity （％） Natural Non processed ３ passes ＋ Natural ３ passes Non processed+Natural ５０％ ２

Assessment of the quality of concrete to use processed recycled aggregate: =Summary= ・ Compression strength, tensile strength,modulus of elasticity, dry shrinkage,durability factor,neutralization of concrete which use recycled aggregate processed by VSI are equivalent to or better than those of the concrete which use crushed or natural aggregate. =Conclusion! Recycled aggregate which is processed by VSI is applicable to concrete for the construction. ・ Non processed recycled aggregate has lower strength, higher dry shrinkage, remarkable drop of durability factor. =Conclusion! Non processed aggregate is not applicable to concrete for construction but for very limited uses. ２３２３

4. Development concept of Kemco RC7 =High quality recycled aggregate production system= “key concept” of its development 1. Production of high quality aggregate. a) To comply with “H” grade of JIS b) To produce sand well quality controlled by air screen. 2. Quality control of product. 3. Low initial cost thanks to “Dry system” 4. Low running and maintenance costs thanks to VSI & Air screen 5. Less space requirement, non dust and low noise. ２４２４

Outer view of RC7 BM 7 Air Screen Dust collector Product stock pile ・ All the equipment are in vertically integrated flow and in compact style. ・ Low noise, no dust low vibration => Environmentally friendly ２５２５

１ pass ２ pass ３ pass Processing flow of system Crushing and shaping by BM7 Classification, sieving and cleaning of the surface of aggregate by air screen Stock bin for subsequent process More passed Product ２６２６

BM 7 ・ Vertical shaft impactor (More than 1,200 units were supplied to market) ・ “Rock on rock” crushing can remove cement paste easily. ・ Low running cost by セルフライニング方式 ２７２７

Air Screen(RCAS) ・ 4 layers of sieves ・ Classification, sieving and cleaning of the surface of aggregate by air screen. => Multi function ２８２８

Working mechanism of air screen ２９２９

Numbers of passes  Density and Water absorption （ Fine aggregate ） １～２ pass ・・・・ “ Ｌ ”grade of JIS ３ pass ・・・・・・・ “ Ｍ ”grade of JIS Classification by density ・・ ・・・ “ Ｈ ”grade of JIS （ Coarse aggregate ） １ pass ・・・・ “ Ｌ ”grade of JIS ２ pass ・・・・ “ Ｍ ”grade of JIS ３ pass ・・・・ “ Ｈ ”grade of JIS ３０３０ Classification by density

（ Product ） Coarse （ Product ） Sand (Material) Images of product ３１３１

Model line-ups of RC7 ・ 3 model lines-ups are available per capacity. Model ＲＣ７－１ＲＣ７－２ＲＣ７－３ Feed －４０ｍｍ ４０ｔ／ｈ６０ｔ／ｈ８０ｔ／ｈ Volume of stock bin １０ｔ／ｈ１６ｔ／ｈ２０ｔ／ｈ Max capacity １２０ｔ／ｈ１９０ｔ／ｈ２５０ｔ／ｈ Dust collector ３６０ｍ ３ ／ｍｉｎ６００ｍ ３ ／ｍｉｎ８００ｍ ３ ／ｍｉｎ Barmac Hustler ＵＳ３０１ＨＵＳ３２２ＨＵＳ３９４Ｈ Air Screen ＲＣＡＳ１２００ＲＣＡＳ１９００ＲＣＡＳ２５００ ３２３２

RC7 Pilot plant for sample test We are ready to run test for the customer. Required material volume is 3 tons ３

Thank you! Kotobuki Engineering & Manufacturing Co.,ltd.