## 2 Materials and Methods  
Experiments were carried out to evaluate the impact of winter contaminants on the skid resistance of a runway, as well as the impact of common liquid RDPs used in anti-icing and de-icing modes. All the measurements were conducted under controlled cold conditions in the UQAC's snow chamber. Concrete cement paving stones of dimensions 10 cm \(\times\) 20 cm \(\times\) 5 cm were used as test substrates, as shown in Figure 1(Permacon Heritage Universal Paver, Anjou, Canada). These paving stones were selected as substrates since their surface roughness and absorption characteristics correlated well with the actual concrete surfaces found at most Canadian airports. Although the surface roughness is less than that of some airport surfaces, it serves as a point of comparison for the conditions targeted in the study. Each stone was cleaned using tap water and dried at room temperature. Figure 1b shows the BPT setup with the concrete substrate mounted for test. The pavements and testing apparatus were conditioned at the test temperature in the cold room (\(-15^{\circ}\) to \(-5\,^{\circ}\)C) for 24 h prior to testing. The skid measurements were undertaken using the BPT according to ASTME303 [13], and the BPN was obtained. The smaller the BPN, the more the surface will slide and is considered risky. Conversely, the bigger the BPN, the less the surface will slide. The BPT is primarily used to assess microtexture. This test is commonly supposed to have a slip speed of 10 km/h, and microtexture is thought to rule in low-speed applications [30]. Prior to each testing day, the  
Figure 1: (**a**) British Pendulum Tester (BPT) in operation in the cold room and (**b**) the concrete cement test substrate. apparatus was levelled and the zero verified. The contact surface was also verified using a ruler to ensure that the slider was in contact with 125.0 \(\pm\) 1.6 mm [13]. Seven conditions were excerpted from the RCAM and reproduced in the laboratory [22]. A plan summarizing the tests is presented in Figure 2, with their schematics shown in Figure 3.  
The first test consisting of the dry \"as-is\" condition is considered as the reference value, which is equivalent to a RWYCC of 6 (no treatment prior to testing). The second condition represented the wet condition, where the concrete was fully wetted with water at room temperature, with a RWYCC of 5. The first two conditions were conducted at 20 \({}^{\circ}\)C. Following the RCAM, the next conditions were reproduced using lab-harvested natural dry snow particles. The third test refers to the \"removed snow\" condition conducted at \(-15\)\({}^{\circ}\)C; snow was sifted and compacted on the stone with a low pressure and then removed using a scraper. In this condition, all the pores of the concrete were filled with snow and a thin layer of snow remained on the surface. This reproduced a compacted-snow condition, with an equivalent RWYCC of 4. The fourth test condition consisted of dry snow which was obtained using a 1 mm sift to deposit approximately 4 mm of snow. The thickness of snow was measured at five different positions using a metallic ruler. The snow was not compacted during the deposition process, so it was easily removed during the passage of the pendulum slider. The equivalent RWYCC is 3. The same methodology was used to obtain the fifth test condition, wet snow, except that the snow was exposed to a simulated freezing drizzle precipitation for a period of six minutes, drizzled at a targeted intensity of 8.5 g/dm\({}^{2}\).h. This condition also corresponds to a RWYCC of 3. The latter two conditions were conducted at \(-10\)\({}^{\circ}\)C.  
Figure 2: Test plan of the seven GRF icing conditions [22] selected for this study. The sixth condition consisted of ice obtained by simulating a freezing drizzle precipitation, with a nozzle of median volumetric diameter of 115 \(\upmu\)m (Nozzle #650017) being drizzled at a targeted intensity of 8.5 g/dm\({}^{2}\)-h at \(-5\,^{\circ}\)C for six minutes.