Abstract
The durability of consolidated highly porous limestones was tested after salt and freeze–thaw cycles. Three porous limestone lithotypes that were commonly used in construction in the Central-European region during previous centuries were selected for the tests. Specimens of Miocene limestone were consolidated with four different types of ethyl silica-based consolidants (KSE 100, KSE 300, KSE 300 E, KSE 300 HV). After consolidation, the samples were exposed to freeze thaw cycles and salt crystallization tests. Water saturation under atmospherically pressure, capillary water absorption and splitting tensile strength were measured on treated and untreated samples to assess change attributed to consolidation in the open porosity and mechanical parameters. The increase in the tensile strength of the medium-grained samples was higher than that of the consolidated fine-grained lithotypes. The effect of consolidation treatment was very different in terms of pore-size distribution as obtained by Mercury intrusion porosimetry (MIP). Untreated and consolidated samples were subjected to 10 cycles of sodium sulphate crystallization (EN 12370) and 10 freeze–thaw cycles (EN 12371) tests. Experiments concluded that in addition to the initial strength increase after the conservation, the modified pore structure is the crucial factor to evaluate the long-term efficiency of stone conservation.
Highlights
The consolidation of porous weathering-sensitive stones is very common in restoration practice
The texture of the three lithotypes is different, and this difference is reflected in their tensile strength
The silica acid esters consolidants increased the strength of the lithotypes but this improvement is not long-lasting since when the stones are subjected to freeze–thaw or salt crystallization, a rapid loss of strength was recorded
Summary
The consolidation of porous weathering-sensitive stones is very common in restoration practice. Despite the short-term strengthening effect of consolidants, several properties of the stones change. The disadvantages of these treatments only appear in the long term. The current paper provides additional information on the durability and long-term behavior of consolidated porous limestone using laboratory tests to assess the ethyl-silicate treated specimens’ mechanical properties and the limestone’s textural changes. It focuses on the testing of low durable stone, a porous Miocene limestone. Similar Miocene limestone types are known from other central European countries such as Austria and Slovakia [5], and the Czech
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