Evaluating the performance of calcium tartrate as a consolidant for soft limestone

Abstract

In this study, as-quarried desalinated Maltese Globigerina Limestone (GL and artificially weathered GL test blocks were conolidated with calcium tartrate (CaT) starting off with a precursor solution of ammonium tartrate AmT). The latter was applied by capillary uptake. X-ray diffraction studies confirmed that a crystalline form of calcium tartrate CaT) was deposited within the stone pore network even though CaT is about 30 times more soluble than calcite. TI1e deposition of CaT was further confirmed by electron microscopy. Drilling resistance measurements bowed that the mechanical properties of the CaT consolidated limestone blocks were markedly improved over untreated stone. Consolidation however led to pore blocking and this severely limited the ability of the stone to ab orb water. Appropriate control of the concentration of AmT and choice of appropriate application method (brush, poultice a opposed to capillary uptake) is proposed to limit this effect.