Environmental accounting on treatment and reutilization of construction sludges in geotechnical engineering fields

In Japan, although the recycling of waste has been promoted, there may be various obstacles. In this study, we focus 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, we quantitatively assess the benefit of recycling by adding the time factor to the evaluation model with consideration for cost and environmental load. 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.