Zanqun Liu

Characterization of Cement Asphalt Mortar for Slab Track by Dynamic Mechanical Thermoanalysis

AbstractCement emulsified asphalt (CA) mortar is a key engineering material for ballastless slab tracks of high speed rail (HSR) and has a wide range of asphalt to cement (A/C) mass ratios. Depending on the A/C ratio, CA mortar may be composed of either cement-based or asphalt-based materials. In this paper, based on typical field service conditions of CA mortar of HSR and the characteristics of CA mortar, the testing conditions of dynamic mechanical thermoanalysis (DMTA) for CA mortar were determined, including by measuring the mode, specimen size, frequency, heating rate, and temperature range. Results show that DMTA characterized in this study indicates high repeatability and is an appropriate method for evaluating the thermodynamic mechanical properties of CA mortar. The vibration damping ability of CA mortar increases with an increase in asphalt content within a temperature range of (−40 to 60°C).

Na2SO4 Salt Weathering of Calcium Sulfoaluminate Cement Paste Partially Immersed in a Na2CO3 Solution

AbstractNa2CO3 is considered to be a salt that causes destructive weathering distress on cementitious materials. In this paper, calcium sulfoaluminate (CSA) cement paste was partially immersed in a...

Salt Weathering Distress on Concrete by Sulfates?

Generally, the idea of sulfate attack on concrete means that a complex physiochemical process including several harmful productions formation through chemical reaction, such as ettringite and gypsum, following the crystal growth of these productions in cracks or pores resulting in concrete damage. However, another concept was given more and more attention that “salt weathering/physical salt attack” on concrete partially exposed to environment specially containing Na2SO4 or MgSO4. ACI (American Concrete Institute) created a new subcommittee, ACI 201-E (Salt Weathering/Physical Salt Attack) in 2009. In 2011, an ballot was performed to discuss if it is necessary to separate the “physical salt attack” from chapter 6 “sulfate attack” as chapter 8 for ACI 201.2R. There were also more and more reports discussing this topic [2-9]. It seems that this topic will be high interest and relevance for the concrete community.