| Budget Amount *help |
¥3,470,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥270,000)
Fiscal Year 2007: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
At first, in order to develop a porous concrete that can reduce the traffic noise, a series of experiments to measure the normal incident sound absorption coefficient of porous concrete by impedance tube method have been conducted. How to reduce the weighted equivalent continuous sound pressure level (Leq) of a sound absorption panel made of porous concrete has also been studied. Aggregate used in porous concrete panels were lightweight pumice aggregate, limestone aggregate, and ferro-nickel slag aggregate. Leq of the sound absorption panels measured by sound level meter at the frequency of 1/3 octave band from 100 to 2000Hz was obtained. The following conclusions can be drawn from the experimental results. 1) Noise reduction effect of porous concrete panel evaluated by normal incident absorption coefficient and by decrease of weighted equivalent continuous sound pressure level had the same characteristics frequency. 2) Porous concrete of ferro-nickel slag aggregate had a higher noise
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absorption effect than porous concrete of pumice or limestone aggregate. 3) Decrease of Leq by porous concrete panel was about 5 to 30 dB higher than the attenuation of Leq. 4) For the porous concrete panel made of pumice or limestone, sound energy transmitted through the void structure resulted in lower sound absorption capacity than that made of ferro-nickel slag. For the porous concrete panel made of pumice or limestone, at the frequency around 500Hz, which was corresponding to the first peak of sound absorption coefficient, decrease of Leq was not so large because sound energy transmitted through the void structure of porous concrete panel to the other side.
Next, porous concrete was experimentally applied to the purification of water quality in two stage. In the first stage, effects of porous concrete on removing of polluted substance from sewage investigated in laboratory. Influences of void content and size of aggregate in porous concrete on purifying ability were examined. In the second stage, porous concrete products were experimentally set in a moderate polluted river. From the test results, the following conclusions can be drawn. 1)Purifying ratio of TOC, T-P and T-N by porous concrete specimen in laboratory test varied from 60 to 80%, 20 to 40% and 85 to 95%, respectively. And purifying ration of T-P of river water was about 70%. But, in-situ purifying ratio of T-N was far less than that of obtained from laboratory test. Less
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