An industry-academia joint research group consisting of Yokohama National University, domi Environment Co., Ltd., Jiwat Co., Ltd., Recycling Research Organization, and Ecolab Co., Ltd. has developed a method for producing recycled soil that neutralizes alkaline construction sludge at low cost and in large quantities. developed.
Among industrial wastes, the recycling rate of construction sludge generated by tunnel construction work is lower than the recycling rate of asphalt lumps and concrete lumps, and tends to level off.The reason is that recycled soil made from construction sludge is often alkaline, limiting its use, and it takes labor and cost to recycle it by adding neutralization treatment.
This group has been conducting joint research with the aim of establishing a technology for producing high-quality recycled soil by neutralizing alkaline construction sludge at low cost.The recycled soil manufacturing method that has been successfully put into practical use this time consists of the following steps.
First, a solidifying material or the like is mixed with alkaline construction sludge and reformed (reform solidification step).Next, a water absorption modifier is added and the mixture is cured from a hedro-like state to a semi-solid state (modified solidification curing step).Next, it is granulated by a soil improvement machine having a crushing function and adjusted to a particle size that is easy to use as recycled soil (unraveling granulation step).When further cured to promote the hydration reaction, the construction sludge becomes smooth fine-grained solidified soil (hydration reaction promoting curing step).Finally, carbon dioxide is exposed to neutralize the regenerated soil (carbon dioxide contact step).
With this technology, existing modifiers, machines, equipment, etc. can be used to inexpensively, mass-produce, and reliably produce high-quality recycled soil in the neutral region from construction sludge, and its range of use is expected to expand significantly.In addition, as a secondary effect, in the carbon dioxide contact process, carbon dioxide is reacted with the alkali in the soil and fixed as calcium carbonate, so that the effect of reducing carbon dioxide emissions can be expected.
