Haoxia Ma,Hongfa Yu,Jinliang Tian,Yongshan Tan,Bo Da
Icing pressure testing was conducted to investigate the icing pressure ( I p ) of chloride-based deicers and discuss the relation between I p and the freeze-thaw deterioration of concrete induced by chloride deicers. During the icing pressure test, when the solution transformed from the liquid to the solid phase, undercooling occurred, and the heat of the liquid-solid phase transformation was released. The I p of chloride deicers and water reached a plateau near −30 °C. The stable I p value of water was the highest of that of the chloride solutions followed by that of 3.5% NaCl; the I p of 3.5% CaCl 2 was slightly higher than that of 3.5% MgCl 2 . The concept of the I p cumulative effect with time ( S ) was first proposed to determine the freeze-thaw destruction induced by chloride-based deicers. The durable life of the concrete exposed to chloride-based deicers decreased with the S of the deicers, and the mass loss of the concrete increased with the S of the deicers.
The rapid freeze–thaw test about ordinary Portland cement concrete (PCC) was performed in the deicers of water, 3.5% ethylene glycol, 3.5% NaCl and 3.5% calcium magnesium acetate (CMA). The ice pressure ( I p ) of deicer was tested, and the concept of the ice pressure impulse ( IPI ) was proposed. A crack density model was employed to describe the freeze–thaw damage process of concrete. Results indicated that the freeze–thaw damage of PCC in CMA deicer was the mildest. The I p value of water was the highest but its IPI value was the lowest. The freeze–thaw microcracks inside concrete was induced by the I p of deicer restrained in concrete pores. The freeze–thaw crack density decreased with the relative depth of specimen. The value of superficial critical crack density was 0.85 ∼ 0.88, when the exterior mortar of concrete began spalling. The value of central critical crack density was 0.32 ∼ 0.34, when the interior freeze–thaw failure of concrete occurred.
Acetate-based deicers are frequently used as airport pavement de-icing fluids in cold regions. In this study, the ice pressure ( I p ), icing volume expansion rate ( Δ V P ), freezing point ( T 0 ), and undercooling degree of acetate-based deicers were investigated. The above mentioned indices were also compared with that of water and NaCl deicers. The results showed that the cooling process and ice crystal growing process of acetate-based deicers could be divided into five stages. Additionally, the stabilised values of I p and Δ V P decreased with the deicer concentration increases. Furthermore, the impulse concept of ice pressure ( IPI ) was proposed to evaluate the frost damage of concrete caused by deicers. The I p , Δ V P , and T 0 values of calcium magnesium acetate (CMA) deicer with different Ca/Mg mole ratios (i.e. 1/1, 0.91, 7/3, and 3/7) were tested in the ice pressure test. The value of CMA deicer with 3/7 Ca/Mg mole ratio was the lowest. However, the I p values of CMA deicers with 0.91 Ca/Mg and 1/1 Ca/Mg mole ratios were the highest. Among all the tested acetate-based deicers, CMA deicers had the lowest values of I p , Δ V P , and IPI . Moreover, the CMA deicer with 3Ca/7Mg mole ratio was recommended for deicing airport pavements to reduce the concrete frost deterioration caused by acetate-based deicers. In this study, we investigated the physical properties of acetate-based deicers, quantitatively analysed the destructive power of deicers in a freeze–thaw test, and studied the cause of freeze–thaw deterioration of concrete. Overall, this study provides a theoretical method for exploring new deicers.
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