It is important for coal fly ash and/or any other recycling materials to guarantee not only quality and safety of surround environment but also durability due to promoting the utilization. This study focused on the durability of coal ash mixed material which is made by cements, water, coal fly ash and soil. Also, this study focused on wetting and drying test as one of the durability test. This paper reports, 1) durability evaluation of coal ash mixed material on wetting and drying test, 2) assessment of the effect on the environment of coal ash mixed material considering the various environmental degrading factors. As a result, it was revealed that the compressive strength of coal ash mixed material that underwent wetting and drying decreases as degradation progresses regardless of the solutions. And the degradation mechanism depends on the type of solution of durability test.

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This paper provides initial findings regarding the utilization of tire chips in the form of vertical and horizontal layer placed beneath the shallow foundation. The effectiveness of such configuration was investigated numerically using PLAXIS 2D software. The user defined soil model (UDSM) - UBCSAND model of PLAXIS was used as the material model so that the liquefaction behavior able to be captured. Structural displacement, acceleration response and pore water pressure ratio were selected as the indicating factors to measure any improvement made. Furthermore, the effect of various intensity of the seismic motion towards the numerical model also discussed. In general, the presence of horizontal and vertical layer made of tire chips significantly improves the performance of the shallow foundation under the seismic motion in the previously stated indicating factors.

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In Japan, although the recycling of waste has been promoted, there may be various obstacles. This study focuses on construction waste, more specifically, construction sludge, which is less advanced in terms of recycling. Processing cost for materials recycled from construction sludge is higher compared to the cost of mining virgin materials. There are some additional difficulties including delays in schedules due to the time required for processing and the balance between supply and demand. Therefore, the benefit of recycling by adding the time factor to the evaluation model with consideration for cost and environmental load is quantitatively assessed. As a result, it is shown that the bottlenecks of construction sludge recycling are higher cost than the cost of mining of virgin materials, high heavy metal contents in the construction sludge, and delays in the recycling process.

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Waste recycling has become a worldwide trend to reduce waste generation as a means to help alleviate pollution and impede depletion of natural resources. In Hong Kong, approximately 90,000 tonnes of waste glass, the majority of which contains beverages, are disposed of every year. As glass is chemically inert, instead of burying them in the landfills, the feasibility of recycling waste glass as an engineering fill material in reclamation works and earthworks has been studied. A series of laboratory tests have been conducted on crushed pure glass samples of sizes of 3 mm minus and 20 minus to investigate their physical and engineering properties. The results of the study have indicated that with proper engineering control, it is technically acceptable to use glass cullet as an engineering fill in both reclamation and earthworks. Technical requirements for using glass cullet as engineering fill have been developed. This paper presents the feasibility study undertaken and discusses their results. It also highlights the major technical requirements proposed for the use of glass cullet in reclamation and earthworks.

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The Great East Japan Earthquake generated a huge amount of disaster-related waste. If soil generated from wood chips derived from woody waste materials is to be effectively used as a material in soil structure, the settlement and stability characteristics of this material should be considered. In this study, a series of laboratory tests was carried out, exposing soil composed of different ratios of wood chips to varying compaction degrees. The unconfined compressive strength decreased and the stress–strain curve exhibited more ductile behaviour as the wood chip content increased, while the opposite tendency was exhibited as the compaction degree increased. Deviator stress was not influenced by the mixing rate. The cement-mixed soil exhibited the effect of curing on strength properties, with crushed stone concrete-mixed soil displaying similar tendencies.

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The most powerful earthquake, the 2011 Tohoku Earthquake, occurred on March 11, 2011. The north-eastern region of Japan have been most seriously damaged by the tsunami waves devastated the Pacific coast. Total amount of tsunami sediment was estimated around ten million ton in Miyagi, Iwate and Fukushima prefectures. It is necessary to use the tsunami sediment soil by construction materials in reconstruction works in north-eastern area in Japan. In this paper, an author proposed a reuse method of tsunami sediment soil by mixing with stabilizers, such as steel slug and concrete sludge. To improve strength of tsunami sediment, the blast furnace slug was used, however, a long time is necessary to enhance the strength of soft soil improved by blast furnace slug alone. To accelerate the hardening time, the author added concrete sludge as an alkaline irritant to awake the potential hardening effect of blast furnace slug. The strength of tsunami sediment soil improved by blast furnace slug rapidly increased by adding the concrete sludge. The improved tsunami sediment achieved the target strength for construction materials within short period and it was applicable for the construction of embankment or fill material.

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Utilization of the soils recovered from the disaster debris is one of the geoenvironmental challenges related to the 2011 East Japan earthquake and tsunami. The disaster debris contained significant amount of soil fractions and these soils are expected to be separated from the disaster debris and utilized in re-construction works in the areas affected by the disaster. In this paper, generation and treatment of disaster debris are briefly summarized. Mechanical properties of recovered soil were discussed from the viewpoint of composition, compaction, and compressibility in order to utilize it in geotechnical applications. A lower amount of admixed combustible matter can lead a higher quality of recovered soils as a geo-material. Difficulty of characterizing the recovered soil and feasible strategies for utilization are also briefly discussed based on the experimental results.

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