Interfacial properties of composite shotcrete containing sprayed waterproofing membrane

Byungkwan Park , Chulho Lee , Soon-Wook Choi , Tae-Ho Kang , Jintae Kim , Myung-Sik Choi , Seokwon Jeon , Soo-Ho Chang

Abstract

This study evaluates the interfacial properties of composite specimens consisting of shotcrete and sprayed waterproofing membrane. Two different membrane prototypes were first produced and tested for their waterproofing ability. Then composite specimens were prepared and their interfacial properties assessed in direct shear and uniaxial compression tests. The direct shear test showed the peak shear strength and shear stiffness of the composites\' interface decreased as the membrane layer became thicker. The shear stiffness, a key input parameter for numerical analysis, was estimated to be 0.32-1.74 GPa/m. Shear stress transfer at the interface between the shotcrete and membrane clearly emerged when measuring peak shear strengths (1-3 MPa) under given normal stress conditions of 0.3-1.5 MPa. The failure mechanism was predominantly shear failure at the interface in most composite specimens, and shear failure in the membranes. The uniaxial compression test yielded normal stiffness values for the composite specimens of 5-24 GPa/m. The composite specimens appeared to fail by the compressive force forming transverse tension cracks, mainly around the shotcrete surface perpendicular to the membrane layer. Even though the composite specimens had strength and stiffness values sufficient for shear stress transfer at the interfaces of the two shotcrete layers and the membrane, the sprayed waterproofing membrane should be as thin as possible whilst ensuring waterproofing so as to obtain higher strength and stiffness at the interface.

Key Words

interface; spray; waterproofing; membrane; shotcrete; composite

Address

Byungkwan Park — School of Smarty City and Construction Engineering, University of Science and Technology (UST), Goyangdae-Ro 283, Ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea
Chulho Lee — 1.) School of Smarty City and Construction Engineering, University of Science and Technology (UST), Goyangdae-Ro 283, Ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea 2.) Department of Infrastructure Safety Research, Korea Institute of Civil Engineering and Building Technology, Goyangdae-Ro 283, Ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea Soon-Wook Choiand
Tae-Ho Kang — Department of Infrastructure Safety Research, Korea Institute of Civil Engineering and Building Technology, Goyangdae-Ro 283, Ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea
Jintae Kim and Myung-Sik Choi — Silkroad T&D Co., Ltd., Woni-Ro 341, TaeanGun, Chungcheongnam-Do 32134, Republic of Korea
Seokwon Jeon — Department of Energy Resources Engineering, Seoul National University,Gwanak-Ro 1, Gwanak-Gu, Seoul 08826, Republic of Korea
Soo-Ho Chang — 1.) School of Smarty City and Construction Engineering, University of Science and Technology (UST), Goyangdae-Ro 283, Ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea 2.) Construction Startup Promotion Center, Korea Institute of Civil Engineering and Building Technology, Goyangdae-Ro 283, Ilsanseo-Gu, Goyang-Si, Gyeonngi-Do 10223, Republic of Korea

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