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Earthquakes and Structures
  Volume 5, Number 4, October 2013, pages 477-497
DOI: http://dx.doi.org/10.12989/eas.2013.5.4.477
 


Pinning retrofit technique in masonry with application of polymer-cement pastes as bonding agents
Kshitij C. Shrestha, Sanjay Pareek, Yusuke Suzuki and Yoshikazu Araki

 
Abstract
    This paper reports extensive experimental study done to compare workability and bond strength of five different types of polymer-based bonding agents for reinforcing bars in pinning retrofit. In pinning retrofit, steel pins of 6 to 10 mm diameters are inserted into holes drilled diagonally from mortar joints. This technique is superior to other techniques especially in retrofitting historic masonry constructions because it does not change the appearance of constructions. With an ordinary cement paste as bonding agent, it is very difficult to insert reinforcing bars at larger open times due to poor workability and very thin clearance available. Here, open time represents the time interval between the injection of bonding agent and the insertion of reinforcing bars. Use of polymer-cement paste (PCP), as bonding agent, is proposed in this study, with investigation on workability and bond strengths of various PCPs in brick masonry, at open times up to 10 minutes, which is unavoidable in practice. Corresponding nonlinear finite element models are developed to simulate the experimental observations. From the experimental and analytical study,the Styrene-Butadiene Rubber polymer-cement paste (SBR-PCP) with prior pretreatments of drilled holes showed strong bond with minimum strength variation at larger open times.
 
Key Words
    masonry retrofitting; pinning retrofit technique; polymer-cement paste; pretreatments; barrier impregnants; bonding agent; finite element modeling
 
Address
Kshitij C. Shrestha: Department of Architecture and Architectural Engineering, Graduate School of Engineering, Kyoto University, Kyoto 615-8540, Japan
Sanjay Pareek: Department of Architecture, College of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan
Yusuke Suzuki: International Research Institute of Disaster Science, Tohoku University, Aoba Sendai 980-8579, Japan
Yoshikazu Araki: Department of Architecture and Architectural Engineering, Graduate School of Engineering, Kyoto University, Kyoto 615-8540, Japan
 

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