Natural and Synthetic Consolidants for Earth Heritage: A Review

Abstract

Since ancient times, natural products have been used to preserve earthen structures. Old recipes with cactus resin, bee wax, or linseed oil, have passed through generations and, in some countries, are still used nowadays. On the other hand, 20 th and 21 st centuries brought synthetic products as a solution to restore and conserve historical buildings. Although these synthetic products were extensively studied for stone-based monuments, they are also being used in earth heritage. The act of consolidating a degraded surface is, in conservation field, one of the most sensitive points, since the options available do not offer reliable solutions. Most of the times, the product applied, specifically in earth heritage, do not embrace two of the most important aspects in any conservation procedure: compatibility and reversibility. This paper aims to review the main consolidants (natural and synthetic) commonly used in earth heritage conservation, and also to draw the attention for the importance of a solid diagnosis of the initial state of conservation. With this review, it was possible to understand a lack of homogeneity in the identification of decay phenomena, as well as in recognizing its mechanisms of occurrence, and consequently in choosing the proper consolidant or treatment.

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

“…In order to not only assess the possibility of using contact sponge method to characterize initial water absorption on earthen materials but also to have a comparative study before and after treatment, three different water repellent products were applied on both adobe and rammed earth specimens. The selection of water repellent was based on the most commonly used products, according to the literature [15], [49], [50]. Therefore, one synthetic and two natural products Two layers of each product were applied on one surface (exposed surface in a wall) using a brush, to simulate a real case scenario.…”

“…A significant number of publications, conferences, seminars, and round tables have been organized [13]. However, there is still a lack of knowledge regarding degradation phenomena and, consequently, on choosing the right treatment to be used [14], [15]. Following conservation theory and charters (essential as a background for any intervention in heritage)…”