Smallest Average Weight Loss

There was a little difference (By comparing Mixes 2 and 4, it can be concluded that the addition of agro-based chemicals has improved the ice melting capacity of the deicers. This conclusion comes from the fact that Mix 5 is only made of sodium formate, but Mix 4 is made of sodium formate, and plant extracts. Higher ice melting capacity of Mix 4 demonstrates the positive effect of sugarbeet and dandelion leaves extracts on the ice melting capacity of the deicers. This is in good agreement with the results published by Jungwirth and Shi (2017).

Based on the LC-MS results, plant extracts (especially sugarbeet extract) contain nitrogen containing compounds which are considered ice melting agents. This is maybe due to the polar structure of these chemicals which enables them to be adsorbed to the surface of ice particles and weaken the bonding between ice molecules which can promote ice melting process. In addition, LC-MS data show that the plant extracts contain alcohols which are well known freezing point depressants.

Ranking of anti-icer mixtures according to ice-melting capacity after application of anti-icers at 60 min, -3.9°C (ordered from greatest to least, error bars represent standard errors). It should also be mentioned that since the maximum amount of the plant extracts used for each mixture is 6 wt.% or less, it is significantly lower than the commonly used alternative of 23% NaCl brine and sugarbeet juice at 80:20 by volume. In addition, the use of such agro-based formulations with increased anti-icing effectiveness have lower application rates than plain 23% NaCl brine, further reducing the amount of chemicals needed for providing a reasonable level of service on wintry pavements.

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Freeze-thaw resistance of PCM in the presence of anti-icers Figure 4 illustrates the weight loss of PCM samples exposed to anti-icer solutions after 10-day freeze-thaw test. Mix 11 showed the highest impacts towards mortar. The average weight loss of the mortar samples exposed to Mix 11 was 2.3%, followed by 2.2% for Mixes 13 and 14. The control showed about 1.5% weight loss. Notably Mix 2 and Mix 1 caused, respectively, 0.13% and 0.01% weight gains on samples. Since scaling was observed on the samples exposed to these anti-icers, the weight gain can be attributed to the absorption of anti-icers. The effect of various anti-deicer mixtures on the weight loss of PCM samples after 10-day freeze-thaw test (ordered from least to greatest, error bars represent standard errors).

The impact of deicers on mortar samples can be due to a mixture of physical and chemical attacks which damages the integrity and the strength (Farnam et al. 2015). The physical attack is mostly caused by cyclic freeze-thaw. It can have different forms such as scaling, map cracking, and paste disintegration. Salts can cause scaling of the cementitious materials through osmotic pressure, precipitation and growth of salt crystals, thermal shock, and glue spalling. On the other hand, the chemical attack can be in the form of chemical reactions of deicers with cement paste and aggregate phase which can weaken the cementitious materials. For instance, Portlandite [Ca(OH)2] may react with deicer ions which can cause formation of expansive oxychloride compounds. The rate of reactions depends on the diffusion coefficient of chloride ions. Usually it takes less than 3 hours for chloride ions to penetrate to the depth of 300 µm in a concrete sample and reach equilibrium.

Since the main additive in Mix 1 is sugarbeet byproduct, it can be concluded that sugarbeet extract molecules caused less scaling in PCM samples after F-T cycles. In addition, by increasing the concentration of the plant extracts (Mix 6 → Mix 8), the salt-scaling damage was reduced, which again confirms that plant extracts have improved the deicer–scaling resistance of PCM samples. Yang et al. studied the deicer-scaling resistance of the cement-based mortar samples containing ammonium phosphate and the mortar samples made by ordinary Portland cement. Their study showed the positive effect of ammonium phosphate on increasing the deicer–scaling resistance of mortar samples. Based on the LC-MS results, the sugarbeet extract contains both amino and phosphate compounds, and dandelion extract contains amino compounds. Therefore, the molecules containing amino and phosphate chemicals in the extracts are active ingredients that increased the resistance of mortar samples against deicer–scaling damage.

Effect of freeze-thaw in the presence of anti-icers on PCM strength The average compressive strength of the mortar samples exposed to different anti-icer solutions after 10-cycle freeze-thaw (F-T) testing is shown in Figure 5. It can be seen that there is no relationship between the weight loss results (Figure 4) and the compression test results. For example, the least average weight loss belongs to Mix 2, but the maximum compressive strength is associated with Mix 5. Actually, the compressive strength is more affected by frost damage rather than scaling damage. Frost damage is mainly due to the osmotic pressure. Since in this research the PCM samples are non-air-entrained, they are more susceptible to this damage. The results obtained in this section imply the significant beneficial effect of silicate and the moderate role of formate on the compressive strength of PCM samples. It is in good agreement with Phoo-ngernkham et al. observations which showed that silicate phase can react with concrete and produce crystalline CSH phase which can improve the mechanical properties of concrete