SARA – The Use of Domestic Clay as a Sustainable Building Material

Introduction

 

The key themes in the Innovation and Skills in Finland 2021-2027 program are a carbon-neutral
Finland and the transition to a circular economy. With climate change, the construction industry
has recently paid more attention to sustainable construction and using natural materials.

Clays in Southwestern Finland have been found challenging when used as construction
materials, e.g., due to the highwater content and, in some places, the high sulfur content and
acid production potential (acid sulfate soil material). Clays in Finland are typically defined
according to how they behave under different load situations. There is little information on
how excavated Finnish clays can be utilized as a part of the built environment. Adding more
information allows for the broader use of clay.

In Finland, large volumes of potentially usable clay must be transferred and disposed of from
construction and civil engineering projects. The utilization of these clay masses requires new
ways of studying and treating the masses, and to this, the SARA project seeks to find new
solutions. Local excavation clays could be used in clay construction instead of being placed,
for example, in urban landfill areas. Clay masses already deposited can also be used if the
properties of the clays and their suitability as raw materials for new products are known. The aim
is to find new uses and thus promote the transition to a circular economy.

If the clay could be used to make products without firing, it would save energy during the
production stage. In addition, reducing natural raw materials and construction waste favors the
use of clay in ecological construction. The goal is to develop and obtain unfired clay tiles and
bricks suitable for construction use. The strength of unfired clay products can be improved by
adding recycled materials, such as textile fibers, natural fibers, or fibrous waste streams from the
forest industry.

Due to the large clay volumes to be excavated during construction, the clay should also be used
in infrastructure projects. Surplus clay has been used, e.g., in the construction of noise barriers
and to stabilize softer grounds to be built on. New larger-scale uses could be, for example, flood
protection products or other prefabricated constructions. In infrastructure construction, ashes
and slags from local heat and combustion plants can also be used to substitute ordinary cement.

The project takes into account the needs of companies that use clay as raw materials, as well
as clay builder education. The industry branches involved find the project tasks and objectives
relevant for their future actions/efforts.

The measures of the SARA project will be implemented in five work packages. The circular
economy and carbon neutrality are present throughout all work packages. The solutions are
based on traditional and new insights. The knowledge gained will be distributed in cooperation
with companies, universities, and research institutes as the future clay construction model
for using domestic clay as a building material. The work packages together form a consistent
whole on the availability, composition, development of clay products, and product testing of
finished clay products. Piloting provides concrete evidence of the potential of clay construction.
In addition, the work packages will provide more information on the clay products’ environmental
impact and carbon footprint. The information can be used in companies and cities to support
decision-making to reduce the carbon footprint.

The primary result of the project is to provide the target groups information on recycling and
utilization of domestic clay. Companies can use the results of this project to develop new green
growth businesses. The project will enable better reuse of material and waste streams alongside
and as substitutes for virgin natural resources.

Main partner: Åbo Akademi University
Other partners: Turku University of Applied Sciences and GTK

Contacts:

Thomas Kronberg
Åbo Akademi University
thomas.kronberg@abo.fi

Maarit Järvinen
Turku University of Applied Sciences
maarit.jarvinen@turkuamk.fi

Hilkka Kallio
Geological Survey of Finland GTK
hilkka.kallio@gtk.fi

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