This paper deals with the behaviour of waste pozzolanic materials, such as fly ash (FA), ground granulated blast furnace slag (GGBS), rice husk ash (RHA) and burnt brick powder (BBP)-based geopolymer concrete (GPC) under a repeated freezing and thawing cycles. The study focuses on the impact of curing regimes (24 h, 48 h, 7 d and 28 d) and exposure to 25 and 35 F-T cycles on the mechanical and durability characteristics of GPC. In recent literature, analytical and numerical work has shown that micro-crack evolution and interconnected pores dictate the degradation of strength under cyclic freezing but limited experimental data are available for waste-based GPC systems. The concretes were mixed into specimen and cured at $60^{\circ}\text{C}$ in an oven for 24 h and tested according to standard F-T testing (ASTM C666). It was found that the loss in strength up to 35 cycles did not go beyond 18 %, and residual compressive strength was higher than 80% of original one, passing durability criteria according to ASTM C666 or EN 12390-9. The relationship between the strengths in compression and tensile strength, both of F-T aged and natural samples, were roughly linear ( $R^{2}\approx0.85).$ Deeper potassium hydroxide activation and the enrichment of RHA and BBP in the AC enhanced the porosity while decreasing the mass yields, as compared with previous results. These findings demonstrate the potential uses of waste-based geopolymer concretes as environmentally friendly and frost-resistant substitutes for ordinary Portland cement in construction in sub-arctic environment.
WMAN (wireless metropolitan area network) technology is based on the IEEE 802.16 air interface standard suite, which provides the wireless technology for fixed and nomadic data access. WMAN employs orthogonal frequency division multiplexing (OFDM), and supports adaptive modulation and coding depending on the channel conditions. The objective of this paper is to study the performance of the IEEE 802.16d WMAN physical layer under Nakagami model as a Multi-path and frequency-selective fading channel beside the additive white Gaussian noise (AWGN) and Doppler. Finally, we compared it with the Rayleigh fading model. The transmission bit rate, Probability of Error ( ) and estimated SNR have been compared under single/multi path propagation conditions.