2006 Fiscal Year Final Research Report Summary
Quality control and durability of concrete with recycled aggregate
| Project/Area Number |
16560399
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Civil engineering materials/Construction/Construction management
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| Research Institution | Okayama University |
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Principal Investigator |
AYANO Toshiki Waste Management Research center, Associate professor, 廃棄物マネジメント研究センター, 助教授 (10212581)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Recycled aggregate / Water absorption / Slump / Strength / Drying shrinkage strain / Sulfate attack resistance |
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| Research Abstract |
The quantity of demolished concrete is about 40,000,000 tons a year in Japan. 65% of demolished concrete was crushed and made good use as an aggregate for pavement base and so on in 1997. This amount reached to 98% in 2000. The use of demolished concrete is increased year after year. But it is used as pavement base or the reclamation materials as ever. The amount of demolished concrete is expected to be ten times in a few decades. Many researchers have already found it possible to produce a normal strength concrete with the required slump by using recycled concrete aggregate. However, it has been also clear that the durability of concrete with recycled concrete aggregate is sometimes very inferior to that of concrete with virgin aggregate even if the compressive strength of both types of concrete are the same.
The concrete with recycled concrete aggregate was inferior to that with virgin aggregate in most properties of concrete. The water absorption of recycled aggregate is very important factor to express the deterioration of each performance on concrete strength, drying shrinkage and resistance to sulfate attack. The effect of cement paste of recycled aggregate on the carbonation is small. The carbonation of concrete with crushed concrete specimen cast in our own laboratory is almost same as that with virgin aggregate. The big carbonation speed modulus of concrete with crushed demolished concrete may be due to the foreign objects in the demolished concrete. The conclusion is as follows: the performance of concrete with recycled aggregate is inferior to that with virgin aggregate. But the effect of recycled aggregate on deterioration of concrete performances can be expressed by the water absorption of recycled aggregate.
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