Natural zeolite powder in cementitious composites and its application as heavy metal absorbents

Abstract

To lower the carbon footprint and alleviate global warming, it is essential to reduce cement consumption in concrete. In an endeavour to mitigate the problem, use of virgin cement can be curtailed by adopting pozzolanic materials as a partial substitution to cement. To address the constraint, present study investigated the properties of cement pastes blended with natural zeolite powder of size up to 50 μm as a partial replacement to cement. Owing to the presence of a greater quantity of reactive silica and alumina , zeolite has interesting aspects that relate to its pozzolanic behavior. This study presents the strength and durability behavior of zeolite blended concrete with up to 30% replacement to cement, in addition cement-hardened pastes were examined for microstructural properties. The progress of hydration of cement and consumption of portlandite was determined quantitatively by a thermal analysis test after 48 days of hardening. The results showed that use of zeolite powder delayed the hydration leading to a decrease in compressive strength up to 28 days. As a pozzolan material, zeolite needs a longer hydration time and it gains strength and dense structure at later curing ages, perhaps samples can lower the porosity with curing time. Interestingly, zeolite was very effective in absorbing heavy metals, zeolite added cement paste shows significantly lower leached heavy metals than the control specimen owing to its high absorption capacity . • Zeolite plays an important role in reducing carbon footprint. • Coarse zeolite particles may show better physical and mechanical properties. • Porosity and water absorption increased with the increase in zeolite concentration. • Zeolite needs a longer hydration time, it can gain strength and dense structure at later curing ages. • Zeolite added concrete shows excellent heavy metal absorbent capacity.