The Use of Contact Sponge Method to Measure Water Absorption in Earthen Heritage Treated with Water Repellents

ABSTRACT

Earthen heritage represents an important legacy regarding construction history and technological development, with a significant cultural value that must be preserved. According to UNESCO, around 10% of the World Heritage is built using earth, and 57% of these heritage structures are in danger. Although the interest regarding earthen heritage has grown in the last few years, there is still a significant lack of knowledge in terms of material characterization, especially from conservation science point-of-view. In particular, tests regarding water absorption are always difficult to perform with a material that changes completely when in contact with water. Indeed, due to the presence of clay particles, a normal capillarity test is almost impossible to perform. Moreover, water is responsible for a significant number of degradation phenomena often found in earthen heritage. As a result, there is an urgent need to develop suitable water repellent treatments and to evaluate their efficiency. For this reason, this study focuses on the contact sponge method to assess water absorption rates for adobe and for rammed earth specimens treated with three different water repellents — siloxane, linseed oil, and beeswax. Two sets of specimens were prepared and tested, showing that this method can represent an effective way to measure initial water absorption in earthen materials, and promising results from the tested water repellent treatments were found.

KEYWORDS:

• Contact sponge method
• earthen heritage
• water absorption
• water repellents

Acknowledgments

The support from grant PD/BD/114411/2016 is gratefully acknowledged. This work was partly financed by FEDER funds through the Operational Program Competitiveness Factors (COMPETE 2020) and by national funds through the Foundation for Science and Technology (FCT) within the scope of project SafEarth PTDC/ECM-EST/2777/2014 (POCI-01-0145-FEDER-016737).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Fundação para a Ciência e a Tecnologia [PD/BD/114411/2016,PTDC/ECM-EST/2777/2014].