Recycling soil is worthwhile

Antti Nokelainen and Johanna Alakerttula

Recycling soil materials improves the economic conditions for infrastructure construction.

In almost every industry, carbon neutrality and the circular economy are issues that are now being improved through various measures. Construction is one of the industries full of opportunities, as it handles large volumes of raw materials and soil. The EU has also set strict targets for it in terms of both the circular economy and carbon dioxide emissions. Construction also featured in the recently published circular economy programme.

In construction, the circular economy is very often associated with construction waste. However, the opportunities for infrastructure construction to promote the circular economy should not be forgotten, as aggregates are non-renewable natural resources and therefore their resource-wise utilization is very important.

A study was conducted at the University of Tampere to investigate the current state of the circular economy of soil materials and development opportunities in infrastructure construction companies. The study revealed that the circular economy of soil materials has been an essential part of infrastructure construction projects for a long time. In infrastructure construction, the need for a circular economy of soil materials arises when some construction projects generate excess soil materials as a result of excavation and excavation work, and correspondingly, some projects have a need for excess material.

For example, in road construction, large quantities of low-quality clay and sand soils are replaced with aggregates in the construction of road bearing layers. When soil materials are replaced with others, a situation arises in which a utilization target must always be determined for some of the materials. If a utilization target cannot be found, the only option is to place them in a landfill.

The properties of the soil and the planning of recycling are crucial.

In the circular economy of soil, an essential limiting factor is that the qualitative properties of the soil should meet the requirements of the reuse target. The study showed that each different soil type has its own reuse targets. The table presents the reuse targets for different soil types.

The utilization of surplus materials can be enhanced by proactively monitoring and planning soil surpluses and needs. It is unlikely that all surplus soil can be recycled, but the goal should always be to minimize the amount of soil going to landfill and to facilitate the smooth matching of soil surpluses and needs between different construction sites.

The most important factor in efficient soil recycling is efficient and well-planned soil logistics. Systematic recycling reduces soil transport distances, which also reduces carbon dioxide emissions from construction.

Efficient soil management can also improve the economic viability of construction projects. Recycling soil can reduce costs. Logistics costs, landfill fees and the cost of virgin raw materials are reduced.

Text: Antti Nokelainen and Johanna Alakerttula

Antti Nokelainen is a development engineer at YIT.
Johanna Alakerttula, CEO of Akkukierrätys Pb Oy, is a doctoral student at the University of Tampere.

CICAT2025 The research project Catalysts for the Circular Economy: From Innovation Ecosystems to Business Ecosystems is accelerating the transition to a sustainable circular economy.

Material	Utilization target
Aggregates	Surplus aggregate is processed and utilized, for example, in street construction and other load-bearing structures.
Moraine and sand	Used in fills and structures that do not have high load-bearing requirements.
Clay and silt	Recycled for use in, among other things, the production of growing media, landscaping, and noise barriers.