The thicknesses of concrete elements required to achieve various fire resistance ratings (FRR) in New Zealand are notional and are based on overseas building codes and test results.
Because of the variations in the properties of the constituent aggregates, a test programme was undertaken to determine the reliability of the notional ratings when applied to concrete containing locally produced aggregates.
Two series of tests were conducted. The first series was reported in SR34, while this report covers the second series and concludes the work. Recommendations are made for changes to the minimum required slab thicknesses and minimum required concrete cover to reinforcing steel to achieve specified fire resistance ratings.