INFLUENCE OF ZEOLITIZED PERLITE ON BLENDED CEMENT PROPERTIES

Perlite is the mineral of volcanic origin. Expanded perlite has good heat insulation and sound absorption properties. It is light, resistant to fire, moisture and micro-organisms, harmless to health. However, due to the presence of hyaline phase, its use in Portland cement mixture is problematic. In this paper, the zeolitization of expanded perlite was carried out to improve its hydraulic properties. The conversion of expanded perlite into zeolite material was carried out when Na2O : Al2O3 : SiO2 : H2O molar ratio was equal to 2: 1: 2: 10 and the suspension of starting materials was treated for 3 hours at 100°C temperature. Mechanical and physical properties of hardened cement paste containing 0%, 5%, 10%, and 15% of pure perlite admixtures, zeolitized perlite, and perlite altered to calcium (Ca2+) zeolite were researched. The results showed that zeolitization of expanded perlite activates its hydraulic properties; after 28 days of hydration under normal conditions, the compressive strength of the specimens modified with 5% of zeolitized perlite admixture was 49-50 MPa, whereas the compressive strength of the specimens containing 5% of pure perlite admixture was only 33 MPa.