The Effect of Natural Zeolite on Lightweight Concrete Production
Lightweight concrete is produced using a variety of lightweight aggregates like volcanic pumice, clay, fly ash, slate, or shale. It is often used in house construction and applications can include foundation reinforcement, fire resistance, or filling voids in sewer systems, pipelines, and fuel tanks. As developers face increased demands for new materials that are environmentally friendly, studies examine the effects and benefits of natural zeolite in lightweight concrete mixes.
A study by Jitchaiyaphum et al. (2013) tested cellular lightweight concrete (CLC) made from performed foam, Type-I Portland cement, fly ash, or natural zeolite. Properties measured included compressive strength, setting time, water absorption, and microstructure. Results indicated that CLC containing 10wt% of natural zeolite had the highest compressive strength (Jitchaiyaphum et al., 2013). The replacement of Type-I Portland cement with zeolite decreased the total porosity and air void size but increased the capillary porosity of the CLC. Finally, the incorporation of zeolite decreased the setting time, total porosity, and pore size of the paste compared with mixtures containing the same amount of fly ash (Jitchaiyaphum et al., 2013).
De Gennaro et al. (2008) tested the use of mixtures containing natural zeolites in the production of lightweight concretes. All products and mixtures were tested by means of fusibility and firing tests to evaluate the expanding properties. Results indicated that natural zeolitized materials mixed with DPM (30 wt. %) provide lightweight aggregates with densities ranging between 0.8 and 1.0 g/cm 3 suitable for the preparation of structural lightweight concretes (De Gennaro et al., 2008).
Karakur et al. (2009) used clinoptilolite zeolite was used as an aggregate and bubble-generating agent in aerated concrete production. The researchers examined the effects of particle size, replacement amount, and curing time on aerated concrete properties. Results demonstrated that the use of natural zeolite has a positive effect on the physical and mechanical properties of aerated concrete. The optimal replacement amount was 50 percent; at this rate the compressive strength, unit weight, and thermal conductivity of aerated concrete were measured as 3.25 MPa, 0.553 kg/dm 3 and 0.1913 W/mK (Karakur et al., 2009). Researchers concluded that zeolite acts as both an aggregate and bubble-generating agent.