Physical-chemical study, characterisation and use of image analysis to assess the durability of earthen plasters exposed to rain water and acid rain. (30th October 2018)

• Record Type: Journal Article
• Authors: García-Vera, Victoria E.; Lanzón, Marcos
• Is Part Of: Construction & building materials. Volume 187(2018)
• Page Start: 708
• Page End: 717
• Publication Date: 2018-10-30
• Subjects: Earthen plasters -- Surface characterisation -- Acid rain -- Durability -- Image analysis; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2018.07.235
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: The binder nature has little influence on physical properties of earthen plasters. The curing conditions have an influence on physical properties of earthen plasters. Earthen-based plasters have low resistance to rain water and acid rain. Gypsum patina formed by sulphuric rain improve the surface resistance of plasters. Image analysis allows the assessment of textural alterations produced by acid rain. Abstract: This paper aims to determine the physical performance and rain resistance of earthen plasters made with a red clayey binder, rich in silico-aluminates and a yellow binder which is mainly calcareous. The nature of the binder had little influence on practical properties of plasters, such as density, consistency, shrinkage, consumption, thermal conductivity and capillary water absorption. However, important properties of the plaster as for instance, the cohesion of the surface were affected by the type of binder. In addition, the plasters durability was evaluated by rain erosion tests conducted with distilled water and acid rain simulated with hydrochloric and sulphuric acid solutions (5% w/w). It was found that earthen plasters showed a better resistance to sulphuric acid than to hydrochloric acid. Scanning electron microscopy and X-ray diffraction analyses confirmed the formation of gypsum coatings on the surface of plasters attacked by sulphuric acid. In this case, the erosion was smaller due to the passivating role of gypsum, which protects the underneath material from dissolution. The textural alterations assessment, evaluated by optical microscopy and image analysis software, showed that hydrochloric acid rain was the most aggressive attack, followed by sulphuric acid rain and rain water.