Abstract
As the cement industry is responsible for 7% of the global CO2 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.
Highlights
Ordinary Portland cement (OPC) is a widely utilized building material
The objective of this study is to investigate the effect of natural zeolites (NZs), originating from one Serbian deposit, used as a partial substitute of OPC at various weight replacement rates, on compressive strength, flexural strength, capillary water absorption, water absorption at atmospheric pressure, drying shrinkage and frost resistance of blended cement mortars
NZ as an supplementary cementitious materials (SCMs) contributes to the compressive strength development over time, i.e., it can be used for the substitution of OPC up to 20% in blended cement mortars, as the decrease in compressive strength at the age of 28 days is about 10%;
Summary
Several inherent disadvantages of OPC are challenging to overcome, including (i) high energy consumption, i.e., cost-effectiveness, (ii) natural resource consumption, a primary lack of availability of aggregates and (iii) emission of greenhouse gasses, such as CO2. The use of locally available waste materials as a partial alternate of aggregates/cement in the concrete design can notably reduce the environmental burden. These include fly ash (FA), silica fume, ground granulated blast furnace slag, and other calcined natural pozzolanic materials such as rice husk ash and metakaolin. The European Standard EN 206 provides the guidelines on how to design an appropriate concrete composition and achieve a durable structure conforming to the exposure classes identified therein.
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