○Limited Use of Concrete [2]

     Residents' modes of transportation within the community involve traveling at speeds of up to 20 km/h in automobiles, and for mid to long-distance travel between communities, trains are used. Consequently, the need for highways constructed with concrete is eliminated.

    However, concrete remains necessary for train tracks and structures requiring strength, such as tunnels or bridges. Within the community, roads are constructed with concrete minimally and prioritize cobblestones, reducing concrete usage. This approach not only reduces concrete usage but also enhances the community's aesthetics. Any remaining concrete usage would be directed towards embankments or potentially dams, if needed.

    During Japan's Meiji era when large construction machinery wasn't available, an artificial stone was developed. This material was used in large-scale projects such as harbor construction and irrigation channels. The artificial stone was a mixture of decomposed granite (10 parts) and lime (1 part). In areas without decomposed granite, suitable clays or volcanic ash soils were occasionally used.

    This artificial stone had the property of solidifying in water. It was used to form a thick protective layer on the outer side of structures like embankments and sluice gates by combining mixed soil with natural stones. In this process, about 10cm of mixed soil was placed between natural stones, preventing direct contact between them. Then, it was compressed from above using pounding tools like a pounding rod, requiring significant manual labor.

    This artificial stone is also appreciated for its ability to return to nature. Hence, if suitable for road construction in terms of strength, it could be considered as an option.

    Furthermore, there's a development where a mixture of 100 parts soil, 40 parts sand, 30 parts hydrated lime, and water are used to form walls in houses.

    Depending on the soil type, different hardening agents are used. Cement is used for soils with more sand content, while hydrated lime (produced by adding water to quicklime) is used for clayey soils. The materials and proportions mixed vary based on the soil's characteristics, altering the way the soil solidifies.

    In the future, if methods emerge to solidify soil without using limestone similar to concrete, it might become an alternative. However, presently, by limiting the use of concrete and transitioning away from a monetary-based society, there is potential to significantly reduce carbon dioxide emissions.