HAYEN, ROALD1; GODTS, SEBASTIAAN2; DE CLERCQ, HILDE3

1 Ir, Royal Institute for Cultural Heritage, Monument Laboratory, Roald.Hayen@kikirpa.be

2 Royal Institute for Cultural Heritage, Monument Laboratory, Sebastiaan.Godts@kikirpa.be

3 Dr, Royal Institute for Cultural Heritage, Monument Laboratory, Hilde.DeClercq@kikirpa.be

On the heights of the Coudenberg hill, overlooking the city of Brussels, once stood one of the most beautiful palaces of Europe. Under the reign of Philip the Good a prestigious banqueting hall – the Aula Magna – was constructed, while Charles V, one of the most powerful Western emperors, personally oversaw the further development of the palace during the 16th century. However, on the 3rd of February 1731 tragedy struck as almost half of the palace was destroyed by a fire. While certain lower parts were later on integrated as cellars and foundations of the neo-classical buildings, the foundations of the Aula Magna were buried under the Royal Square in the 18th century. Thanks to recent excavation works, the remains of the former palace of Brussels are accessible for the public.

The brickwork remains of the Aula Magna are, however, severely damaged: the bricks are heavily fragmented and continuously falling apart. The influence of the climate and the presence of soluble salts are examined to identify the probable cause of damage. Different grouting and repair mortars were developed and evaluated. Brick powder was added as pozzolanic component to adjust the colour of the grout to that of the bricks and to prevent the occurrence of lime blooming at the surface of the masonry.

Keywords: historic brickwork, climate, grouting, brick powder, pozzolana