For stressed
and unstressed tests (Figures 6 and 7), the Eurocode and CEB design curves are unconservative for both
NWA and LWA HSC in the temperature range between room temperature to about 350 °C. It should be
noted that the majority of explosive spalling failures were reported to have occurred at approximately this
temperature. Above 350 °C, the code design curves are more applicable to both HSC and NSC, which is
consistent with experimental observations that the difference between HSC and NSC decreased at about this
temperature. For unstressed residual property tests (Figure 8), the Eurocode and CEB design curves are in
better agreement with HSC data at temperature between 25 °C and 400 °C than for unstressed tests.
However, the design curves appear to be slightly unconservative for both NWA and LWA HSC and also for
NSC at above 250 °C. For modulus of elasticity, only CEB explicitly recommends design curves for LWA
and NWA concrete, which are unconservative compared with unstressed test data for both NWA and LWA
HSC. For unstressed residual property tests, the design curve for LWA concrete appears to be in good
agreement with data for LWA HSC (Figure 9a). However, the design curve for NWA concrete remains
unconservative compared with data of NWA HSC (Figure 9b).