In cold regions, highways, airfields or sidewalks are exposed to de-icing agents to thaw the ice layer on pavement surface. In this situation, a progressive surface damage that pulls off flaky chips from concrete pavement takes place. This damage is named as frost salt scaling. To produce scaling-resistant concrete and prevent the damage in the field, the deterioration mechanism should be understood well. For this aim, a number of mechanisms have been hypothesised in literature. However, there is no unique one which can be used to explain all observations from laboratory tests and field applications. In this study, a novel hypothesis that is built on earlier findings in literature is introduced. According to the proposed mechanism, the pressure applied by forced brine from outer strong ice layer, which adhered to surface, causes scaling in the strongly ice adhered regions. The published events that are unexplainable by a unique former mechanisms proposed in literature related to the frost scaling are rationalised based on the proposed mechanism.

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The effects of curing regimes varying combinations of temperatures (ambient, 60 °C, 75 °C, 90 °C, 105 °C) and durations (4h, 8h, 24h, 48h, 96h, 168h) on the performance of fly ash added pumice based geopolymer pastes were investigated in this study. The precursor raw material consists of 70% pumice dust and 30% fly ash (FA). Alkali activator was prepared by mixing 10M sodium hydroxide (SH) solution and liquid sodium silicate (SS) in the ratio of SS/SH=2. Activator to precursor ratio was fixed as 0.45. Compressive strengths were determined at the 28 days of age as well as after exposure 5 wetting-drying (w-d) cycles. In addition, Fourier Transform Infrared Spectroscopy (FTIR) tests were conducted on the fresh and hardened geopolymer pastes in order to examine the effect of curing conditions to the structural changes and reaction products. The results show that in the case of 60 °C and 75 °C, the strength of the w-d conditioned samples increased steadily as the curing time increased. However, longer curing times of more than 24 hours are not beneficial for high curing temperatures (90 °C and 105 °C). The maximum strength after the w-d cycles is obtained for the curing conditions of 60°C/168h (74.4 MPa). Also, FTIR analysis confirmed that the hardened geopolymer paste transformed into a more coordinated structure and soluble carbonate compounds were reduced at 60 °C and 168 hours curing condition.

The effect of sodium hydroxide (SH) concentration and sodium silicate (SS) content in alkali activator on mechanical properties and wet-dry resistance of fly ash added pumice based geopolymer paste were investigated. In the study, the concentration of SH was used as 8, 10, 12 and 14 molar, while the weight ratio of SS to SH was used as 0, 1, 2 and 3. While the density of geopolymer paste samples increased significantly with the increase of SH molarity in mixtures with low SS content, it was less affected by SH molarity in mixtures with high SS content. For all SH molarity values, the compressive strength of the geopolymer paste samples increased with the increase of the SS/SH ratio, while a slight decrease was observed with the SS/SH ratio increasing from 2 to 3. However, with the increase of the SH molarity, the compressive strength of the samples was less affected by the SS content. As large cracks or splits occur in paste samples activated only with SH under the effect of wet-dry, their compressive strength could not be measured. The wet-dry performance of the paste samples activated with SS + SH was not affected much by the SH molarity and the SS/SH ratio and were close to each other. When looking at the microstructure studies, FTIR analyzes show that SS content provides a better geopolymerization, and SEM images show that micro-cracks relatively decrease with SS content.