Resistance of Cement Paste and Its Relationship to Strength under the Corrosive Action of Ambient Media

Weilun Wang, Shiqun Li, Jiashan Hu, Feng Xing

Guangdong Provincial Key Laboratory of Durability for Civil Engineering, Shenzhen University, Shenzhen, China.
School of Materials Science and Engineering, University of Jinan, Jinan, China.

DOI: 10.4236/eng.2012.46038                

Abstract

In this study, we measured the resistances (test frequency 837.8 Hz) of the paste of Portland cement (PC) and phosphoaluminate cement (PALC) subjected to different types of corrosion and different numbers of freeze-thaw cycles. This study aimed to improve understanding of the changing characteristics of paste resistance from both micro and macro perspectives by associating changes in the paste microstructure with changes in the paste mechanical strength using X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and other methods. Our results showed that changes in the paste resistance under the corrosive action of ambient media could signal the deterioration of paste structure and loss of paste strength. Continuous hydration reactions within the paste were found to render it more dense and increase its resistance. Invasion of corrosive ions was found to continue to increase paste resistance if the structure of the cement paste was not destroyed. Otherwise, paste resistance would decrease. Corrosive media were found to cause the dispersion of hydrated gels with certain degree of polymerization. Because spatial resistance was found to cause difficulty in the transportation of ion clusters, the decreases in resistance caused by long-term corrosion might be reduced due to a compensation effect. This effect was found to be related to the severity of structural damage to the paste. The magnitudes of corrosive effects of chemical media on the radicals in the cement paste structure were found to occur in the following order: SiO4 > AlO4 > PO4. The resistance and strength of the PC was always lower than those of PALC. In addition, losses of resistance and strength by PALC were mainly due to deterioration of the radical structure of AlO6.

Keywords

Cement Paste; Ambient Media; Resistance Characterization; Microstructure; Strength

Conflicts of Interest

The authors declare no conflicts of interest.

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