Wei-Wen Li,Wei-Ming Ji,Yi Liu,Feng Xing,Yu-Kai Liu
This study aimed to explore the damping property of a cement-based material with carbon nanotube (CNT). In the study, the cement composites with different contents of CNT (0 wt%, 0.033 wt%, 0.066 wt%, and 0.1 wt%) were investigated. Logarithmic Decrement method and Dynamic Mechanical Analysis (DMA) method were utilized to study the damping property of CNT/cement composite. The influences of CNT on pore size distribution and microstructure of composite were analyzed by Mercury Intrusion Porosimetry (MIP) and Scanning Electron Microscopy (SEM), respectively. The experimental results showed that CNT/cement composite presented higher flexural strength index than that of a pure cement paste. Additional CNT could improve the vibration-reduction capacity of cement paste. Furthermore, the experiments proved that CNT could bridge adjacent hydration products and support load transfer within cement matrix, which contributed to the energy dissipation during the loading process.
Xing Ming,Qing Liu,Miaomiao Wang,Yongqing Cai,Binmeng Chen,Zongjin Li
Chloride-induced corrosion in reinforced concrete is a primary durability issue that causes large economic loss every year. To improve the intrinsic chloride binding capacity and realize a favorable corrosion protection of cement-based materials are thus crucial to prolong the service life of concrete structures. Here, alumina nano particles (ANPs) were incorporated to improve the chloride binding capacity of cement pastes in chloride solutions and the anti-corrosion performance of mortars under accelerated corrosion process. The ANPs facilitated the formation of alumino-ferrite-mono (AFm)-type phases, thereby improved the content of chemically bound chlorides. Solution calcium (Ca) ions benefited the chloride captured by calcium-(alumino-)silicate-hydrates (C-(A-)S-H) in the assistance of ANPs, especially at high initial chloride concentrations , and further evoked a pH-related chloride binding response. Moreover, the enhanced corrosion resistance was finally realized by incorporating appropriate amount of ANPs because of the filling and chemical effects induced low permeability of mortars. In general, the ANPs possess dual functions in the aspects of chloride binding and corrosion inhibition . These findings are expected to advance the design of high-durable cement-based materials serviced in the marine environment.
Hong Zhang,Ming Chen,Tiantian Liang,Zanpeng Zhang,Changhui Yang
The use of nanocarbon materials to enhance the toughness of fragile cementitious materials has attracted increasing attention for investigation. This study examines the effects of incorporating graphene oxide (GO) into NaOH-activated slag (AAS) pastes and mortars, focusing on workability, phase composition, mechanical properties, and the local mechanical properties of the interfacial transition zone (ITZ) between sand and paste. The experimental results indicate that the addition of GO decreases the flowability of NaOH-AAS pastes, with noticeable aggregation at concentrations above 0.03 wt%. Furthermore, GO enhances the hydration degree of ground granulated blast furnace slag (GGBS), leading to an increased amount of C-A-S-H gel without introducing new phases. In terms of macro performance, incorporating 0.03 wt% GO significantly improves the compressive and flexural strengths of NaOH-AAS mortars by 10.6 % and 17.9 %, respectively. Additionally, the presence of GO reduces the ITZ thickness from 30 to 15 micrometres in NaOH-AAS mortars, which likely contributes to the enhanced mechanical performance.
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