Water retention and drainage capability of expanded cork agglomerate boards intended for application in green vertical systems

Abstract

The expansion of urban centres, together with the increasing frequency of extreme weather phenomena, have prompted the need to study and implement Natural-Based Solutions that can enhance the sustainability and resilience of cities. In this context, green vertical systems (GVS) have been referred to as eco-efficient solutions with potential benefits in terms of building insulation and urban environment. Nonetheless, the sustainability of these solutions has been questioned due to the possible low environmental performance of some of the materials used and the irrigation needed to support vegetation.This work describes studies that have been performed to evaluate expanded cork agglomerate as an alternative eco-friendly material for building GVS. Expanded cork agglomerate is an insulation material produced with by-products from the industry, which may have benefits when used in GVS in terms of regulating the moisture in the planted facade. Experimental tests were carried out to evaluate the water retention and drainage capability of expanded cork agglomerate boards of varying density, height and thickness.For this, board specimens were fully laterally confined in a watertight box with open ends at the top and bottom, with successive water discharges being carried out on the top. Other tests were performed with the front of the box removed, thus allowing the water to drain from the facade too. The results suggest that expanded cork agglomerate is suitable for use in GVS, with the boards achieving water retention up to 20 kg/m3 and providing rapid drainage of excess of water.