Consolidation of earthen building materials: a comparative study

The consolidation and protection of mud bricks are a challenge in the field of conservation of archeological sites. One of the solutions is represented by the coverage of the entire excavation that assures a protection against mud dissolution. Unfortunately, this is not always feasible, both for economical and practical issues. For these reasons, alternative solutions are needed. In this work, laboratory experimentation has been carried out in order to test the efficacy of some products to slow down the dissolution process and increase the brick toughness. Three typologies of raw materials taken from different outcrops (one from the Republic of Azerbaijan and two from Calabria region, Italy) have been characterized and used to build mud brick specimens. Four consolidation treatments were tested (ethyl silicate, potassium silicate, potassium hydroxide, sodium hydroxide) and different investigations have been performed to check their efficiency against the dissolution in water. Results suggested that the efficacy of each treatment is related to the main intrinsic characteristics of the raw material employed for the mud bricks manufacture. Among the tested products, nanolime and NaOH solution showed very poor performance, while ethyl silicate and KOH could be very promising compounds for successful conservation.