Effect of Different Silicic Acid Ester on the Properties of Sandstones with Varying Binders

This study deals with the effect of using different silicic acid ethyl esters (SAE) on diverse sandstones and to estimate their influence on the properties of the treated stones. Prismatic samples of Baumberger Sandstone (BST), Sander Sandstone (SST) and Nievelsteiner Sandstone (NST) with the dimensions 50 mm×50 mm×100 mm were treated with three different consolidating agents based on silicic acid ethyl ester (KSE 100, KSE 300, KSE 510) in three different procedures (vacuum, 1- and 5- time impregnation). The aim of this study is to demonstrate that differences in application, for instance varying stone consolidation agents, other treatment procedures as well as using sandstone samples with different binders (BST: calcareous, SST: clayey, NST: quartzitic), cause in each case different results concerning the strengthening effect and the success of a consolidation action. Laboratory measurements were performed on treated and untreated material in order to estimate the effectiveness of stone consolidation actions. To detect the influence of subsequent treatment procedures, water vapour diffusion resistance (WVDR) and capillary water absorption (CWA) measurements were carried out. Furthermore, the effectiveness of a stone consolidation was analysed by measuring ultrasound velocity, compressive strength, flexural strength, bond strength by pull-off and the porosity of the stone samples. Due to varying treatment procedures the investigated sandstones showed different petrophysical and mechanical properties (no strengthening effect up to “over-treating”). Different treatment procedures lead to increasing amounts of strengthening agent in the pore space of the investigated stones and as a result to higher values in WVDR (except BST and NST samples), ultrasound velocity and to an improvement in mechanical strength (except compressive strength of NST). This applies in particular to 1-time, 5-time and vacuum impregnated SST and 5-time treated NST and BST, regardless of the used stone strengthener. On the other hand, these different treatment procedures lead often to a decreased CWA and to a reduction in total porosity. The performed measurements indicate a development in strength in case of 5-time and vacuum treatment, but also an increase of the possibility of sealing the pores, especially for SST samples.