Surface-treatment of cementitious materials with [email protected] core shell nanoparticles

Significance 

Concrete is one of the most commonly used materials for structural components constructions. Cement forms the major component in concrete. Production of cement is associated with emissions of carbon dioxide gases which leads to about 5-7% of the global greenhouse gases emissions. Therefore, enhancing durability for the long life of the concrete structures is considered a significant move in the reduction of the greenhouse gas emissions.

Generally, most of the failures in concrete structures are as a result of the surface deterioration due to their susceptibility to external harmful ions. Surface-densification can enhance surface protection through applications of coating materials. They can be classified into organic or inorganic surface treatments. Organic materials have side effects such as short lifespan while inorganic materials are of essential benefits as they use coating materials with similar properties as the matrix. Even though there are several inorganic agents, the use of nanoSiO2 as a surface treatment agent has attracted many researchers due to its properties such as its ability to resist aggregation.

Dr. Yue Gu at Hohai University, Professor Wei She and Professor Jiaping Liu from Southeast University in collaboration with Dr. Qianping Ran who is Chief Engineer of Jiangsu Sobute New Materials Co. Ltd and the Chief Scientist of State Key Laboratory of High Performance Civil Engineering Material and Dr. Xin Shu from Nanjing University investigated the use of nanoSiO2-polycarboxylate superplasticizer ([email protected]) as surface treatment agents for cementitious materials. Additionally, the mechanisms and effects of the nanoparticles surface treatment process were studied. The surface treatment process was investigated by measuring dispersion stability, water absorption ratio, mercury intrusion porosimetry and pozzolanic reactivity. On the other hand, surface-treatment effects on the nanoparticles were explained through a proposed hypothesis utilization the two properties of the nanoparticles which were, dispersity and pozzolanic reactivity. Their research work is published in, Construction and building materials.

The research team observed that [email protected] could be effectively used as surface treatment agents. For instance, it was effective in reducing the water absorption rate while different [email protected] had gone through different influences on the surfaces of the cementitious materials.

The authors used two distinct properties, pozzolanic reactivity and disparity, of [email protected] to describe their refining pore performance. Disparity described the ability to resists aggregation in cement pore solutions during nanoparticle transportation while pozzolanic reaction rate provided the necessary information concerning the density rate of the nanoparticles fillers. The two properties were generally affected by the stability of the cement pore solution. Consequently, surface chemical states of the cementitious materials enabled the [email protected] treatment agent to densify the surface.

[email protected] exhibit flexible chemical structures that enable the design of various [email protected] for surface treatment applications. However, an average shell-core ratio is suitable for [email protected] with similar shell chemical structures. This is because higher shell-ration results to lower pozzolanic reactivity which may not be effective for surface densification. The study would lead to the application of [email protected] for surface treatment of cementitious materials thus increasing their life. As such, structural failures and repairs will reduce significantly leading to the decrease in concrete use, which is also a way of reducing the rate of greenhouse gases emissions.

 

Effects and mechanisms of surface-treatment of cementitious materials with nanoSiO2@PCE core shell nanoparticles. Advances in Engineering

 

About the author

Dr. Yue Gu obtained his Ph.D. degree from Southeast university in 2017. He used to be a Visiting Graduate Researcher at University of California, Los Angeles (UCLA) from 2015/10 to 2016/10. Currently, he works as postdoctoral faculty supported by Hohai University and State Key Laboratory of High Performance Civil Engineering Materials (China). His research interests include enhancing fresh and hardened properties of concrete by nanomaterials, and carbon footprint minimization of cementitious materials.

About the author

Dr.Qianping Ran is the Chief Engineer of Jiangsu Sobute New Materials Co. Ltd and the Chief Scientist of State Key Laboratory of High Performance Civil Engineering Materials (China). His primary research interests lie in the mechanism of construction chemical admixtures and their application in concrete. He has received many awards including Second Class of State Technological Invention Award, Second Class of State Scientific and Technological Progress Award.

About the author

Dr. Wei received his Ph.D. degree from southeast university in 2014. After obtaining his Ph.D., he developed his research in State Key Laboratory of High Performance Civil Engineering Materials (China) for two years, as a postdoctoral fellow. He is currently a lecturer in School of Material Science and Engineering at Southeast University, China. His current research interests include concrete composites, concrete nanotechnology, foamed concrete, durability under extremes, fire resistance and sustainable construction materials.

Reference

Gu, Y., Ran, Q., She, W., Shu, X., & Liu, J. (2018). Effects and mechanisms of surface-treatment of cementitious materials with nanoSiO2@PCE core-shell nanoparticles. Construction and Building Materials, 166, 12-22.

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