Document Type : Research Article

Authors

• hassan afshin ¹
• mohammadhossein ahmadian khameneh ²
• mehrdad emami tabrizi ³
• yasser alilou ⁴
• Gholamreza Qudsi Sharif ⁵

¹ Associate Professor of Sahand University of Technology

² Master student of Sahand University of Technology

³ Assistant Professor, Sahand University of Technology, Tabriz

⁴ Head of Civil Engineering and Architecture Working Group, Scientific, Research and Technology Organization of Alborz Province Technology , karaj , Iran

⁵ Instructor of Sahand University of Technology

Abstract

Shotcrete is extensively used as a concrete reinforcement in underground spaces, for Retrofitting, slope stability, and construction of shell structures. In this research, the performance of recycled micro steel fibers on the compressive and flexural behavior of shotcrete was investigated in two strength categories: normal and high performance. Based on the results, in normal shotcrete, due to the relatively low cement content and lower adhesion, the use of fibers resulted in a 15% decrease in compressive strength. However, due to the higher air pressure in normal dry shotcrete, better performance was achieved with the use of fibers. The use of admixtures in high-performance shotcrete mix designs, in addition to improving rheological properties, increased the average compressive strength by 50%. With the use of fibers, ductile behavior was observed in the plastic deformation range and the load-bearing capacity was continued by the fibers. A constant volume percentage of steel fibers (1%) indicated that the observed differences in energy absorption of the investigated mix designs are related to the concrete matrix. With the use of steel fibers, the minimum required energy absorption at a central displacement of 5 mm in circular panel specimens was met, resulting in an average increase of 58% and 19% in energy absorption in the wet and dry methods, respectively. However, the minimum required energy absorption at a central displacement of 40 mm was not met

Keywords

• Shotcrete
• tunnel
• absorbing energy
• Micro fibers
• accelerator
• dry spray
• wet spray
• Toughness

Main Subjects

• civil engineering