3D mesoscopic investigation of specimen size effect on the compressive behavior of coral aggregate concrete

A novel mesoscale model considering meso-structural characteristic of aggregate

Significance 

Concrete is widely used in the building and construction industry owing to its excellent properties. With advancements in technology and rapid economic and infrastructural development, future structural engineering technology must be tailored to meet the increasing size and performance requirements. This includes conducting thorough studies on the mechanical behaviors of concrete materials. For the past decades, compression test has been widely employed to understand the compressive behaviors of concrete materials under different conditions. In particular, the size effect of the materials and concrete components, which is crucial in constructing large-size concrete structures, is of great importance. Based on the previous research works, uniaxial compressive behaviors of concrete have been greatly associated with height-to-diameter ratios in which the stress-strain curve is size-dependent when the length-to-diameter ratio exceeds a critical point. These revelations opened the way for expansive studies on the compressive behavior of different types of concrete materials.

Coral aggregate concrete (CAC), composed of coral aggregates, cement, seawater, and other admixtures, has been identified as a potential replacement for ordinary concrete. It has been increasingly applied in reef constructions, especially in the United States. Nevertheless, its performance has generally remained lower than that of ordinary concrete, thus limiting its applications. One way of improving the performance and applications of CAC is by understanding its compressive behaviors with different aspect ratios, which requires computer-based numerical simulations such as the mesoscale modeling approach due to the limitations of the laboratory experiments. However, the drawbacks of the mesoscale modeling approach, such as the random characteristic of the aggregate particle, can be overcome by coupling it with a three-dimensional (3D) random particle model that has proved to be highly effective.

In a recent paper published in the Composites Part B journal, a team of researchers at Nanjing University of Aeronautics and Astronautics: Mr. Zhangyu Wu, Prof. Hongfa Yu, and Dr. Haiyan Ma, in collaboration with Prof. Jinhua Zhang from Southeast University, investigated the effects of specimen aspect-ratio (height-to-diameter ratio) on the compressive behavior of CAC based on a 3D mesoscale modeling approach. They aimed to validate the feasibility of using 3D random mesoscale modeling in studying the uniaxial compressive behaviors of CAC with different aspect ratios.

In their approach, the researchers developed a novel 3D mesoscale modeling approach taking into account the random shapes and distributions of coarse aggregates in concrete. CAC cylinder specimen with different aspect ratios (2-6) were investigated to obtain the aspect-ratio effect law on their uniaxial compressive strength. Also, failure patterns, stress-strain relations, and failure processes of CAC were analyzed under compression. Finally, the numerical results were compared to the existing test results to validate the effectiveness of the presented mesoscale modelling approach.

Results showed that the peak displacements of the CAC were proportional to the specimen length. As such, the post-peak stress-strain curves became steeper with an increase in the specimen length, attributed to the localization behavior of the concrete. Consequently, the failure zone length of the CAC specimen was observed to be close to three times (270 – 300mm) larger than that of the specimen diameter (100mm) when the height-to-ratio diameter exceeded 2-3. The results were in good agreement with those of the ordinary concrete. Furthermore, distinctive failure characteristics of CAC cylinders with different aspect ratios revealed a faster failure process in shorter specimens. For longer specimens, however, it showed that the cracks could obliquely propagate in the lateral surface.

In summary, the authors reported the application of 3D mesoscale modeling approach to study the specimen aspect-ratio effect on the compressive behavior of CAC. Based on the simulation results, the rationality of the presented approach and selected material parameters were successfully validated under different conditions. The authors found out that the uniaxial compressive strength of CAC is greatly affected by its aspect ratio, but the strength differences decrease significantly when the aspect ratio exceeds 2.5 – 3. In a statement to Advances in Engineering, said their study advances the development of high-performance CAC materials for numerous construction applications.

3D mesoscopic investigation of specimen size effect on the compressive behavior of coral aggregate concrete: A novel mesoscale model considering meso-structural characteristic of aggregate - Advances in Engineering

About the author

Zhangyu Wu is a Ph.D. candidate in the College of Civil Aviation at the Nanjing University of Aeronautics and Astronautics (NUAA) in China. He obtained his master degree in the College of Aerospace Engineering at NUAA in 2019. He has been awarded the Chinese government scholarship funded by the China Scholarship Council (CSC) to pursue study in the Department of Civil, Environmental & Geomatic Engineering at the University College London of UK from 2020 to 2021. His main research interests are focused on static- and dynamic behavior and failure mechanism of coral aggregate concrete using mesoscale modelling approach. He hosted and participated in several research projects of National Natural Science Foundation, Jiangsu Innovation Program for Graduate Education, etc. So far he has co-authored more than 30 papers in scientific journals and conference proceedings.

About the author

Jinhua Zhang is a Full Professor in the School of Civil Engineering at the Southeast University of China. He received his BEng and MSc degree of Engineering Mechanics in 2002 and 2005, respectively. He did his Ph.D thesis entitled “Development of the Three-dimensional Mesoscopic Model and Analysis of Mechanics and Damage Mechanism for Engineering Materials and Structures under Intense Dynamic Loading” and obtained the PhD degree in Civil Engineering in 2015. His thesis led him to receive the distinction of receiving the “Excellent Doctoral Dissertation” Award of Jiangsu Province. He is the general Secretary of the Engineering Research Center of Safety and Protection of Explosion & Impact of Ministry of Education (ERCSPEIME) at the Southeast University. He is an active member of the International Association of Protective Structure (IAPS).

His main research interests are related to the three-dimensional (3D) mesoscale modelling approach of engineering material, the computation theory and designation method for engineering structure against intense dynamic loading, the protection technology against falling rocks in mountainous region, etc. He hosted and participated in several research projects of National Natural Science Foundation. Through his research he has presented several contributions in several research fields, including the establishment of 3D random mesoscopic model, the analysis method for the macro- and micromechanics of engineering material and structure under intense dynamic loading, and the designation and application of new material and structure in protection engineering. He has published more than 50 papers in International scientific journals, and obtained more than 10 authorized Chinese invention patents and software copyrights.

About the author

Hongfa Yu is a Full Professor in the College of Civil Aviation at the Nanjing University of Aeronautics and Astronautics (NUAA) in China. After he has completed a BEng degree from the Department of architectural Engineering at the Shenyang Jianzhu University (SJU) of China in 1985, he worked as an Associate Research Fellow in the Qinghai Institute of Architecture and Building Materials of China. He joined the School of Materials Science and Engineering at SJU in 1998, and was promoted to Professor in 2000. He did his Ph.D thesis entitled “Study on High Performance Concrete in Salt Lake: Durability, Mechanism and Service Life Prediction” and obtained PhD degree in Structural Engineering from the School of Materials Science and Engineering at the Southeast University of China in 2004. His thesis led him to receive the distinction of receiving the “Excellent Doctoral Dissertation” Award of Jiangsu Province and the “National Excellent Doctoral Dissertation Nomination” Award. After that he got a position as a Professor in the Department of Civil Engineering at NUAA, and served as the Chairman of the department from 2005 to 2010.

As an active researcher and academic, he is the Vice President of China Magnesite & Material Association (CMMA), and the member of many professional associations, including the Architectural Society of China, the RILEM (International Union of Laboratories and Experts in Construction Materials, Systems and Structures) China Chapter, the American Concrete Institute (ACI) China Chapter, etc. He is the Research Fellow at the Qinghai Institute of Salt Lakes, Chinese Academy of Sciences (CAS), and was involved in the Hundred Talent Project of CAS from 2008 to 2013. He was also a Distinguished Professor of “Kunlun Scholar” in Qinghai Province (China) from 2012 to 2015. Currently he is also working in the School of Civil Engineering at the Qinghai University as a Full professor.

His main research interests are focused on new cementitious material, civil engineering material and structure, micromechanics of concrete, durability and service-life prediction of reinforced concrete structure, etc. He hosted and participated in several research projects of National Natural Science Foundation. Through his research he has presented several contributions in several research fields, including the preparation method for Magnesium cementitious material and new concrete material, modified chloride-diffusion theory and concrete durability, and micromechanics of concrete. He developed the Life prediction software “ChaDuraLife V1.0” which is suitable for the reinforced concrete structure in chloride environment, and has employed it in the designation of the Dalian Bay Undersea Tunnel of China. He also developed the micro- and macromechanics calculation software “ChaITZV1.0”, which can provide comprehensive result data and calculation formula for the interfacial transition zone (ITZ) of concrete. He has edited three books and co-authored more than 400 papers in scientific journals and conference proceedings, and obtained more than 30 authorized Chinese invention patents.

About the author

Dr. Haiyan Ma is a Lecturer in the College of Civil Aviation at the Nanjing University of Aeronautics and Astronautics in China. She received her BEng degree from the Department of Engineering Mechanics at Hunan University (HNU) of China in 1998, her MSc degree in Solid Mechanics from Department of Engineering Mechanics at HNU in 2001 and her PhD degree in Structural Engineering from the School of Civil Engineering at Southeast University of China in 2006. Dr. Ma has been awarded the visiting scholarship funded by the China Scholarship Council for academic communication in the Department of Civil, Environmental & Geomatic Engineering at the University College London of UK from 2019 to 2020. Her research interest is mainly related to the micromechanics of concrete.

Her scientific contributions have mainly focused on the static- and dynamic behavior of concrete and the mechanics of building membrane structures. Her seminal contributions focused on the mechanical behavior of concrete under environmental loading and coral aggregate concrete subjected to intense dynamic loading, aimed at promoting the application of coral aggregate concrete in reinforced concrete structures.

She has co-authored more than 130 publications, including research papers in scientific journals and conference proceedings, and she has lead several research projects on the dynamic behavior of coral aggregate concrete at meso-level.

Reference

Wu, Z., Zhang, J., Yu, H., & Ma, H. (2020). 3D mesoscopic investigation of the specimen aspect-ratio effect on the compressive behavior of coral aggregate concreteComposites Part B: Engineering, 198, 108025.

Go To Composites Part B: Engineering

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