The Effects of Natural Zeolite as Fly Ash Alternative on Frost Resistance and Shrinkage of Blended Cement Mortars

As the cement industry is responsible for 7% of the global CO 2 emissions, locally and abundantly available materials are vastly valorized, and their use is assuming a significant role in this domain. Over the last few decades, significant research in the development of supplementary cementitious materials (SCMs) derived from industrial wastes, such as fly ash (FA), has been conducted. However, facing environmental pressures, coal power plants are closing across the planet. Hence there is an urgent need to identify sustainable SCMs that can replace FA in the concrete industry. Furthermore, the usage of FA in cement-based composites does not often produce satisfactory results from the aspect of certain properties, such as freeze–thaw durability. Therefore, the application of natural zeolites (NZs) for these purposes has emerged as an area of interest in the civil engineering practice. This paper presents the results of experimental research regarding the influence of NZ, as a mineral admixture, on the basic physical and mechanical properties of cement mortars, with a focus on frost resistance and drying shrinkage. The amount of NZ was varied from 10 to 30% in relation to cement mass. The findings indicate that NZ positively influences the drying shrinkage reduction regardless of the replacement level, while the best results concerning frost resistance can be achieved in cement blends with 10% NZ.