Fiber Reinforced Lightweight Shotcrete for Patching and Retrofitting of Concrete Structures; Final rept

摘要

Concrete structures may become unsatisfactory as the age of the structure increases. Corrosion of steel reinforcement, excessive deflections, and surface cracking are some causes of deterioration in concrete. One form of rehabilitation of the structure is the use of shotcrete. In the present study, a low-density structural shotcrete was developed. In order to decrease the density, cenospheres were used as the fine aggregate. Cenospheres are ceramic, hollow micro-balloons produced during coal burning processes, and have diameters ranging from 10-300 micrometers. The compressive, indirect tensile and flexural strengths and fracture toughness of the cenosphere-modified shotcrete were determined in accordance with ASTM standards. Dynamic compression and indirect tension tests were performed by the use of a Split Hopkinson Pressure Bar. Water absorption, freezing and thawing, deicing salt resistance, and chloride permeability were tested in accordance with ASTM standards. Lastly, the cenosphere-modified shotcrete was applied to existing concrete in order to evaluate the capacity of shotcrete as an adequate method of rehabilitation.