State of conservation of an industrial brick masonry chimney: a case-study in Montijo, Portugal

Industrial masonry chimneys became widespread in the mid-19th century and were eventually integrated into urban landscapes, gaining significance as symbolic historical remnants of local industries. This poses new challenges, particularly concerning the safety of populations and goods, as well as the preservation of the now-historical structures. In this article, we assess the conservation status of the 45-meter-high chimney of the former cork processing factory Mundet, located in Montijo, Portugal. The study involved a structural survey conducted using height access equipment, along with an investigation to diagnose moisture and salt decay at the base of the chimney. The later included measuring current and hygroscopic moisture distributions, as well as XRD characterization of brick and mortar samples. At the chimney’s base, salt crystallization causes efflorescence and erosion leading to masonry disintegration. This is associated with rising damp and the presence of sodium sulfate in the brick and sodium chloride in the mortar. In the shaft, mortar erosion becomes more pronounced as we ascend. At the crown, extensive mortar erosion and limited compression have caused the NE-facing half to disappear, while the rest is at risk of imminent collapse. Damage mitigation measures to address this situation are proposed.