Grouting in conservation of architectural surfaces : a local study

Abstract

This dissertation investigates the performance of three proprietary injectable grouts : PLM-A, Ledan-TB1 and Iniezione 50. These products are commonly used locally in the conservation of delaminated Globigerina Limestone. Tests on Injectability, Penetration, Fluidity, Volume change, Water absorption by capillarity and Resistance to salt crystallisation were conducted. Combined stone-and-grout cubes were designed and tested in parallel to individual Stone and Grout samples in order to simulate in situ conditions. The results showed that PLM-A and Iniezione 50 had good working properties with Iniezione 50 being the most fluid and having the fastest rate of penetration. Ledan-TB1 remained injectable for a shorter period of time and performed least satisfactory in terms of fluidity and penetration. All grouts were susceptible to shrinkage, PLM-A and Ledan-TB1 experienced greater volume change and developed more shrinkage cracks than Iniezione 50. Ledan-TB1 exhibited the highest discrepancies in capillary water absorption characteristics from Stone. PLM-A was the most durable and maintained adhesion with the stone the longest while Ledan-TB1 was the least durable. The results also suggest that the behaviour of a combined stone-and-grout system is not simply comprised of the addition of the behaviour of Stone alone and Grout alone. It can be concluded that in the light of the local context, Iniezione 50 performs best in terms of working properties and volume change. PLM-A has the best overall behaviour and the best long term performance when in contact with Globigerina Limestone while Ledan-TB1 has the least satisfactory behaviour in both the fresh and the cured state.