Retrofitting of damaged reinforced concrete beams with a new green cementitious composites material

Significance Statement

Overloading of concrete structures leads to short lifetime of structure or even collapse during extreme cases. Rehabilitation of damaged concrete structures in order to meet requirements after carrying high permissible load is a better alternative to demolishing and rebuilding due to present economic climate condition.

Ultra-high performance fiber-reinforced cementitious composite UHPFRCC have been successfully applied in retrofitting or strengthening of reinforced concrete beams. CARDIFRC, one of the techniques of UHPFRCC has benefitting features such as tensile strength, stiffness and coefficient of linear thermal expansion which are comparable with that of parent member material.

 However, CARDIFRC requires high cement content which does not enhance concrete properties but increases emission of greenhouse gases contributing to global warming. In order to overcome this problem, a green-USM-reinforced concrete which has lesser cement content (< 360Kg/m³) compared to 744Kg/m³ of CARDIFRC is currently being developed in Universiti Sains Malaysia USM.

Research conducted by Dr. Aldahdooh and colleagues expanded their findings on green-USM-reinforced concrete GUSMRC as a new green retrofitting material. The work published in Composite Structures examined its flexural behaviors such as crack development, crack modes, flexural capacity and deflection capacity of a reinforced concrete before and after retrofitting

Results from crack development in reinforced concrete beams before retrofitting showed that recorded failure load of three beams of G(0) members was between the range of 37KN to 39.68KN and their failure mode was due to diagonal tension. The third beam reached the highest load of 39.68KN (cycle 16).

The beam A-T20-R20KN-B1 was selected with shear tension failure as the worst failure case. The beam failed when load reached the ultimate capacity of 55.25KN (cycle 22). Compared with results of reinforced concrete before retrofitting, the increase in ultimate failure load of the beam reached 41.3%.

Difference between failure load capacity of both GUSMRC and CARDIFRC were insignificant and at 30KN and 40KN, beams retrofitted with CARDIFRC strips were slightly larger than those of beams retrofitted with GUSMRC concrete strips in terms of ratio of mid-span deflection of beams after retrofitting to before retrofitting

This study proves that GUSMRC can effectively serve as a good retrofitting material.     

Figure Legend :Procedures for bonding the retrofitting GUSMRC strips.
       (a)1^st step                                                          (b) 2^nd step 

  















(C) Last step for this type of retrofitting















(d) Last step for this type of retrofitting
Figure Legend 2: Casting of GUSMRC strips for retrofitting


Figure Legend 3: Steel fiber distribution inside GUSMRC strips

About The Author

Majed A. A. Aldahdooh was born in Palestine in 1987. He received the B.Sc. degree in civil engineering from the Islamic University of Gaza (IUG), in 2009, the M.Sc. & Ph.D. degrees in structural engineering from the Universiti Sains Malaysia (USM), in 2011 and 2014. Respectively. He is currently an Assistant Professor at the University of Buraimi, Sultanate of Oman.

His main areas of research interest are structural design, structural retrofitting, concrete technology and structural health monitoring. Along with his experience in teaching and research; he has several awards including the Ph.D. Fellowship from the USM (2011-2014), the best Ph.D. research award from the USM (2014) and several awards for the excellent achievement in journal publications with high impact factor.

 

About The Author

Norazura Muhamad Bunnori (PhD) has been involved in Acoustic Emission (AE) technique and concrete technologies since 2004 while she was pursuing her PhD study at Cardiff University, Wales, UK. She was graduated from Cardiff University in 2008 and continues with the AE and concrete research areas at Universiti Sains Malaysia (USM), Malaysia. Currently she is working as an Associate Professor at School of Civil Engineering, USM since 2009.

The research covered several topics of AE applications and analysis (quantitative and qualitive) and concrete technologies. The aims are to continue the AE study especially in Structural Health Monitoring (SHM) and concrete technologies research areas and to discover more in these potential areas. The passion towards AE and concrete are deep and she believes that there are a great number of information can be studied and discovered. 

About The Author

Dr. Megat Johari is presently a professor at the School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia 14300 Nibong Tebal, Pulau Pinang, Malaysia. He specializes in Concrete Materials and Technology. He has been teaching Concrete Technology, Civil Engineering Materials, Construction Technology and Structural Retrofitting Technology courses.

He obtained his PhD and MSc (Eng) degrees from Leeds University in 2001 and 1996, respectively, and BSc degree from Ohio Northern University in 1990. He has successfully supervised and co-supervised more than twenty Master and Phd students, where many of them were international students. He has authored and co-authored more than 70 papers, which have been published in refereed journals and proceedings. The published papers have received more than 700 citation based on scopus.

He has served as manuscript reviewer for many international journal such as Construction and Building Materials, Cement and Concrete Research, Materials and Structures, Journal of Hazardous Materials, International Journal of Environment and Waste Management, Journal of Thermal Analysis and Calorimetry, Journal of Civil Engineering and Management and a few other international journals.

Dr. Megat Johari is currently serving as editorial board member for Malaysian Construction Research Journal and Journal of Civil Engineering, Science and Technology. He has been actively involved as speaker in seminars and short courses related to concrete durability, assessment, maintenance as well as repair and strengthening. Besides, he has undertaken many testing and consultancy works related to evaluation of concrete in existing structures.

About The Author

Ali S. Alnuaimi, Associate Professor in Civil and Architecture Engineering Department, Sultan Qaboos University, Oman. Dr. Ali earned his Ph.D. from Glasgow University, UK and his M.Sc. from University of Southern California, USA.

His research expertise focuses on structural design and analysis and estimating construction cost. He published more than 42 refereed journal papers and 33 conference papers. He supervised/co-supervised more than 30 BSc, 10 MSc and 3 PhD research projects. Dr. Ali has vast industrial experience as civil and structural engineer as well as director of projects and maintenance. 

About The Author

Ahmad Jamrah is a full professor of civil and environmental engineering with the Department of Civil Engineering, University of Jordan in Amman, Jordan. Dr Jamrah is currently the Dean of the College of Engineering at the University of Buraimi in the Sultanate of Oman. Dr Jamrah teaches and conducts research the areas of civil and environmental engineering. 

Journal Reference
Majed. A.A. Aldahdooh¹ ,  Muhamad Bunnori², A. Megat Johari², Ahmad Jamrah¹, Ali Alnuaimi³. Retrofitting of damaged reinforced concrete beams with a new green cementitious composites material,  Composite Structures, Volume 142,  2016, Pages 27–34.