A Proposal for an experimental set-up to investigate fire-induced corner damage in R/C members

Corner damage is very likely to occur in R/C columns and beams exposed to fire, in the form of severe cracking and/or spalling. Hence, devising a specific test to assess the capability of a column or beam corner to resist cracking and spalling in case of fire is badly needed. In this paper, a new type of test is proposed, with the aim of reproducing the thermal situation of a plain- or reinforced-concrete corner. Prismatic specimens (80x80x450/500 mm) are introduced inside an electric furnace pre-heated to 750°C, in order to reproduce a very severe fire acting on the two faces meeting at a corner. (The other two faces are kept in roughly adiabatic conditions and made vapor-tight). This rather simple technique is applied to the study of corner damage in three dry/wet self-consolidating concretes (fc = 50, 80 and 90 MPa). In most cases, discrete cracks “cutting” the corner (in plain concrete) or along the bar (in reinforced concrete) appeared, and only in few cases more or less severe spalling occurred. The set-up showed to be effective in allowing a comparison among different mixes, but the limited number of cases with corner spalling was unexpected and is still under scrutiny.