The use of mineral additives, arising from industrial waste, for construction materials such as cement has environmental and economic importance. Also, there is a vital gap between research and issued standards in the wetting-drying field which is well-known as one of the most important corrosive environmental conditions. Only a few pieces of research report non-air entrained fly ash substituted composites exposed to freezing-thawing. In this study, 20% of cement was replaced with fly ash and 60 wetting-drying or freezing-thawing cycles were applied to the samples. For microstructural investigation, cement paste prisms were prepared in two groups of control and fly ash-cement mixtures with the dimension of 40 x 40 × 160 mm. Additionally, 150 x 150 × 150 mm cubes were molded to study the mechanical properties of fly ash-containing concrete subjected to the wetting-drying or freezing-thawing cycles. First series of control and fly ash-added samples after a 28-day curing period were exposed to the purposed cycles. Similarly, the second and third series after 56 and 90 days were exposed to wetting-drying or freezing-thawing cycles. Based on the obtained results, fly ash-containing samples performed better than control mixtures after a 90-day curing period with/without application of wetting-drying cycles since excessive CSH gel was produced as a prominent product of pozzolanic reaction decreased porosity of the mixtures and increased adherence between particles. After the exposure to freezing-thawing cycles, control composites displayed better performance than fly ash-containing samples at early ages. As an important achievement of this study, pozzolanic reactions required at least 90 days to be completed under normal curing conditions at the standard temperature. Due to the required long curing time, partial cement replacement with fly ash can be an efficient alternative for the production of prefabricating elements used in marine construction or other constructions exposed to cold weather.