The study was an attempt to elucidate the compressive strength of oyster shell (OS) aggregate and ground granulated blast furnace slag mortar in different curing condition and to know their amount of solar reflectance, brightness and heat absorption characteristic of the pavements surface which was prepared with study mortar by top filling on open graded asphalt concrete. The compressive strength cylindrical samples were cured in 10℃, 20℃ and 30℃. Light irradiation test conducted in natural condition in 3 consecutive days also in environmentally controlled room, 3 hours light irradiation was applied on 7 types of sample pavements surface. The amount of solar reflection was measured by spectrometric analysis with the wavelength of 380-2,600 nm. At 28 days age, 30℃ water curing samples showed the highest strength for river sand mortar samples, and 20℃ water curing showed the highest compressive strength for OS mortar samples except high early strength Portland cement (HSPC)-OS mortar. Highest compressive strength of HSPC-OS mortar was for 20℃ air curing sample. In brightness, light irradiation test and spectrometric analysis showed that ordinary Portland cement (OPC)-Slag-OS sample is the brightest and highest solar reflector as well as it showed lowest surface temperature within the study pavements.
Currently, the 5TE sensor (Decagon Inc.) is widely used for monitoring soil water content and electrical conductivity. A practical calibration method and validation of the values recorded by the 5TE are required for volcanic ash soils. We investigated a simple correction method to estimate the soil water content (θ) and showed that a calibration approach with a few ( or even one ) points could be used to correct 5TE readings. We also validated estimation method of 1:5 soil to water extract electrical conductivity (EC1:5) and soil pore water electrical conductivity (ECp) with the 5TE. EC1:5 was obtained based on a proportional relation with bulk electrical conductivity (ECa) , and ECp could be estimated from ECa using the Hilhorst model with a simple calibration. However, the measurement accuracy of the 5TE decreased when ECp>1.0 S/m for Toyoura sand and ECp>0.8 S/m for Gandai soil. When θ<0.2 for Toyoura sand and θ<0.275 for Gandai soil, the 5TE could not estimate the ECp. This should be considered when analyzing water content and electrical conductivity values measured in the field with 5TE.
In this study, we investigates the relationship between the degree of degradation of biodegradable resin mortar and exposure conditions in order to use the mortar for temporary materials such as piles and sheet piles. The differences in exposure conditions had a strong correlation with the degree of degradation in the specimens and the rate of mass change, and the surface degradation and the mass changing were caused by microbial biomass. However, the effect of the exposure conditions on strength reduction was small because microbial degradation was very low. Therefore the degradation mechanism of the initial exposure was due to the reduction in bond strength between the biodegradable resin and aggregates by water, and the surface degradation and gradual strength reduction after two months of exposure was due to microbial degradation.
Agglomeration and connectivity of wild boar habitat in the island of Seto Inland Sea Area with citrus fruit production were measured in this paper. As a result, woodland as natural habitat is separated n=44 patch by cultivated fields, while connected woodland by abandoned fields as additional habitat collects together n=13 patch. The maximum patch size is 12.3ha of woodland, while that expands into 41.0ha of connected habitat. Additionally, if cultivated field with no fence behaves as corridor between habitat patch, 80% of habitat area is connected. We showed also the locating method of key patch and corridor with described habitat connectivity by the graph. We can say that fences have function to protect the field itself, but also habitat management function to fragment wild boar habitat in the area, resulting in blocking wild boar inhabitation around cultivated filed.
Steelmaking slag is one of the by-product in steel production. It is important to develop the method of reuse of it since the dawn of history. Recently, it is gaining interest as a material for pavement. Though slag pavement is inexpensive and has good workability, the understanding in the solidification mechanism is not enough. We here examined the relationship between the uniaxial compressive strength and the chemical property for the test pieces made of steelmaking slag and granulated blast furnace slag (GBFS). The uniaxial compressive strength, which increased linearly with aging, of the test pieces containing GBFS showed 3 or 4 times higher strength than that made of steelmaking slag alone. Binder materials, which solidified the void of slag pavement, were hydrated calcium silicate and calcium carbonate. Especially, the formation of calcium carbonate highly correlated with uniaxial compressive strength. The formation of calcium carbonate started at the top and bottom of the layer and gradually proceeded inwards with carbon dioxide supply from the atmosphere and soil air.
Import of rice is increasing and production increase of rice is required from a viewpoint of food security in sub-Sahara Africa. Although an irrigation paddy field is effective in production increase of rice, many canals are unlined, a sudden heavy rain etc. erode them, and a water supply function deteriorates. For this reason, the structure of suppressing erosion is required. But firm reinforcement by cement etc. cannot be performed, since farmers do not have sufficient capital. Then, how to generate a soil hardening material (calcium oxide) easily from the shell (calcium carbonate) was examined as a low cost canal reinforcement measure which farmers can implement. As a result, 800℃ required for calcium oxide generation was obtained using kiln with covering the upper part which can be easily constructed on site. Moreover, it turned out that a calcium oxide can be efficiently obtained by performing two-step burning. Furthermore, it found that the production cost of a kiln is equivalent to five bags (50 kg per bag) of cement.
Typhoon Talas (2011) that attacked the Kii peninsula in September, brought great damage such as a landslide, the inundation by the flood in Kiho-cho, Mie. In Onodanikawa basin, Kiho-cho, the unexpected inundation damage that overflow the ring levee which made by water disaster prevention public project. In this report, we reported functions and problems of voluntary organization from the hearing to the chairperson of voluntary organization for disaster prevention in Funada district and the hearing to the Kiho-cho government office staff for disaster prevention at the time of this disaster. In addition, we reported it about a public role of Kiho-cho that supported voluntary organization for disaster prevention. As results, we confirmed the following. It was necessary to establish the limit of rescue operation beforehand to reduce secondary disaster at the time of the mutual assistance. It was necessary for the unexpected disaster to evacuate by choice independent of the ring levee. The activities of the time of peace of the voluntary organization for disaster prevention produced effects. The cooperation training between voluntary organizations for disaster prevention of Kiho-cho was effective for early restoration.