Abstract:
Aerated concrete (AC), such as cellular concrete, autoclaved aerated concrete (AAC), and
non-autoclaved aerated concrete (NAAC), having excellent insulation properties, is commonly used
in buildings located in cold regions, such as Nur-Sultan in Kazakhstan, the second coldest capital city
in the world, because it can contribute to a large energy saving. However, when the AC is directly
exposed to the repeated freeze and thaw (F-T) cycles, its F-T resistance can be critical because of lower
density and scaling resistance of the AC. Moreover, the evaluation of the F-T resistance of the AC
based on the durability factor (DF) calculated by using the relative dynamic modulus of elasticity may
overestimate the frost resistance of the AC due to the millions of evenly distributed air voids in spite
of its weak scaling resistance. In the present study, the F-T resistance of NAAC mixtures with various
binary or ternary combinations of ground granulated blast-furnace slag (GGBFS) and micro-silica
was assessed mainly using the ASTM C 1262/C1262M-16 Standard Test Method for Evaluating the
Freeze-Thaw Durability of Dry-Cast Segmental Retaining Wall Units and Related Concrete Units.
Critical parameters to affect the F-T resistance performance of the NAAC mixture such as compressive
strength, density, water absorption, air–void ratio (VR), moisture uptake, durability factor (DF),
weight loss (Wloss), the degree of saturation (Sd), and residual strength (Sres) were determined.
Based on the determined parameter values, frost resistance number (FRN) has been developed to
evaluate the F-T resistance of the NAAC mixture. Test results showed that all NAAC mixtures had
good F-T resistance when they were evaluated with DF. Binary NAAC mixtures generally showed
higher Sd and Wloss and lower DF and Sres than those of ternary NAAC mixtures. It was determined
that the Sd was a key factor for the F-T resistance of NAAC mixtures. Finally, the developed FRN
could be an appropriate tool to evaluate the F-T resistance of the NAAC mixture.
