Laboratory Assessment of Selected Protective Coatings Applied on Two Sandstone Types

Abstract

The efficiency of three commercial hydrophobic coatings applied on two types of sandstones was subjected to the tests of water absorption by capillarity, water absorption by complete immersion, and frost resistance. Two days of the curing time of coatings on samples were chosen for the laboratory tests. The effects of the used coatings were different (ambiguous). Two coatings proved their effectiveness and thus, relevance of their use, but different coatings were effective on each type of sandstone. The coating F showed the best efficiency for the Hořice sandstone and coating A for the Malé Skalky sandstone. The third testing coating H was ineffective on both types of sandstone. The water absorption tests by capillarity showed a loss of the coating effectiveness over time. By completely immersing the samples in water, all three coatings lost their effectiveness and the hydrophobic effects disappeared. Applied protective coatings helped to preserve the frost resistance of the Hořice sandstone when looking at the uniaxial compressive strength after 25 freeze–thaw cycles, regardless of their fading hydrophobic effect. In addition, a penetration depth test for Hořice sandstone was performed. The impregnation depth reflects the effectiveness of the coatings and confirmed the results obtained by the water absorption tests by capillarity. The findings presented in the article are also useful in practice, as Hořice sandstone will be mined and frequently used in the future as well.

Factors Affecting the Efficiency of Hydrophobic Coatings—Experience from Application on Sandstone

“…The sandstone contains intergranular cement, which is a mixture of kaolinite, illite, and fine quartz grains [22]. The basic physical properties of sandstone are as follows: bulk density ρd = 1930 kg•m −3 , total porosity n = 26%, open porosity no = 18.3%, water absorption NWAI = 9.5-12.2%, and uniaxial compressive strength UCS = 29.9 MPa [20]. The rock material for the research was taken directly from the Podhorní Újezd quarry in the Podkrkonoší area, which is currently the largest sandstone quarry in the Czech Republic.…”

“…The efficiency of the coatings applied on the sandstone under the specified conditions was evaluated by checking the depth of penetration into the treated sandstone, as well as by water absorption tests. Mainly tests of the absorption by capillarity were carried out, approved as a suitable method in previous research [19,20].…”

Demanda Gold sandstone (Burgos): effect of consolidation and ageing tests on its petrographic and petrophysical properties

“…The most important changes are related to the increase in average pore size, which in both cases (ADDs and ADDTs) exceeds 16 µm, possibly because of the removal of the few clays they contain. Also, microporosity increases slightly (> 30%) to the detriment of macroporosity, which remains dominant (60). The geometry of the pores (0.22-0.17 m 2 /g and 1.14 µm) and their capillary connections (tortuosity = 6.6-2.4) become more regular and straighter, establishing a new fissure microporosity -especially in the treated sandstones (ADDTs) -detected by PLM and FLM.…”

“…While vapour permeability is reduced by one third (~1.14•10 -9 kg/m•s•Pa), air permeability is reduced by up to 60% (~316 mD) (Table 5). ESTEL 1100 effectively restricts the ingress of water in this sandstone, but it also restricts its egress by reducing transpiration, which may affect the durability of this material (25,27,60). Salt aggression does not cause significant changes to the structural and hydric properties of the original sandstone (ADD and ADDT; Table 5, Figure 6-8).…”

Study on the Improvement of Waterproof Performance of Historical Silt Sites with Silicone Waterproofing Agent

“…Silt is a typical poorly graded soil, which often has the characteristics of poor stability of particle skeleton structure and large capillary porosity. Therefore, the harm of capillary water to silt sites is more serious than that of general soil sites [1,2]. Therefore, it is necessary to study the methods to control the capillary rise in silt sites.…”