Deterioration analysis of building calcarenite stone in the House of Venus in the archaeological site of Volubilis (Morocco)

Abstract

The House of Venus was one of the most luxurious Roman houses of the archaeological site of Volubilis in Morocco, built during the first century. It is located in a rural area that has a semi-arid continental climate. The house was mainly built of a yellowish-beige calcarenite. Currently, this stone shows many deterioration features. The objective of this research was to identify the main decay patterns of the calcarenite stone and to investigate the causes of its deterioration. After representative sampling, fresh and weathered stones were characterized using X-ray diffraction, ion chromatography and thermogravimetric analysis. Results show that besides exposure to strong climatic variations for many centuries, stone deterioration was aggravated by interventions using incompatible materials. Halite and gypsum were the main salts detected in deteriorated stones. Potential sources of these salts were also characterized by ion chromatography and thermogravimetric analysis. The contents of both salts are high in mortars and low in soils. They originated in an inappropriate choice of raw materials to formulate restoration mortars.