Title: Freeze-Thaw and Salt Resistance of a Fly Ash Based Pervious Concrete
Author(s): Gang Xu, Luis Gerardo Navarro, Kafung Wong, and Xianming Shi
Publication: Symposium Paper
Appears on pages(s): 41-53
Keywords: pervious concrete, fly ash, geopolymer, freeze-thaw, salt attack, wet-dry, X-ray diffraction (XRD), nuclear magnetic resonance (NMR)
In this work, the freeze/thaw resistance and ambient-temperature salt resistance of fly ash geopolymer pervious concrete specimens were investigated separately, to isolate the physical and chemical phenomena underlying their deterioration during “salt scaling”. The laboratory investigation examined four groups of samples, with portland cement or activated fly ash as the sole binder, with or without graphene oxide (GO) modification, respectively. The incorporation of GO significantly improved the resistance of pervious concrete to freeze/ thaw cycles and ambient-temperature salt attack, regardless of the binder type. The specimens were then examined by using X-ray Diffraction (XRD) method, which revealed that the mineralogy and chemical composition of fly ash pastes differed significantly from those of cement pastes. Nuclear magnetic resonance (NMR) was also employed to study the chemical structure and ordering of different hydrates. This work provides an enhanced understanding into the freeze/thaw and salt scaling resistance of fly ash pervious concrete and the role of GO.