2004 Fiscal Year Final Research Report Summary
Evaluation of Mitigation Characteristics of Heat Island Phenomenon by Porous Concrete Block Using Lapilli
| Project/Area Number |
14550461
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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 |
土木材料・力学一般
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| Research Institution | Akita University |
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Principal Investigator |
KAGAYA Makoto Akita University, Faculty of Eng.and Resource Science, Professor, 工学資源学部, 教授 (00091794)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Absorption / Initial evaporation rate / Outdoor exposure test / Atmospheric temperature / Heat-source effect / Vaporization latent heat / Ordinary concrete / Covering materials |
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| Research Abstract |
The purpose of this research project is to mitigate heat island phenomenon by using porous concrete with the lapilli which was produced in Akita Prefecture and was lighter weight and higher absorption among Japanese lapilli.
Supposing the temperature reduction effect due to vaporization latent heat coming from the absorbed water in the lapilli particles, the properties of the hardened porous concrete including evaporation characteristics were evaluated by using some mixture proportions in the laboratory test mainly(2002).
The heat balance calculation was carried out by the temperature in the center of the cross section area of the exposed porous concrete plate and the heat of the sun's rays measured by a pyrheliometer. A mixture proportion to control the temperature rise in the summer season was chosen, and the durability of the mixture to the drying-wetting cyclic test was examined(2003).
The outdoor exposure test was carried out successively to examine the durability in winter season, a
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nd then the reduction of heat-source effect of ordinary concrete was clarified by measuring the temperature in the center of the cross section area of ordinary concrete plate covered by the porous concrete one(2004).
The following results were obtained.
(1)The initial evaporation rate which was obtained from the relationship between elapsed time and evaporation ratio measured at 20℃, 60% relative humidity environment was an effective index to evaluate the evaporation characteristics. The faster the rate is, the more effective temperature reduction is obtained.
(2)There existed a paste coarse aggregate volume ratio having the maximum initial evaporation rate at 30% of void ratio in the porous concrete. The porous concrete having this mixture proportion was durable in the outdoor exposure test.
(3)The temperature on the surface of the porous concrete plate was 1℃ lower than atmospheric temperature in summer season. The higher the temperature was, the more effective temperature reduction was measured in the outdoor exposure test, and in the case of covering on the ordinary concrete plate by this porous concrete plate, the average temperature in the center of cross section area of ordinary concrete one was about 2℃ lower than mean of atmospheric temperature. It is considered that the porous concrete using lapilli is the covering material to reduce the heat-source effect of concrete structural members. Less
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