Study on the use of lightweight expanded perlite and vermiculite aggregates in blended cement mortars

Abstract

This paper presents an experimental investigation on lightweight aggregate mortars containing high volume cement replacement materials. For this purpose, expanded perlite (EP) and expanded vermiculite (EV) are used as the lightweight aggregate (at sand replacements of 50% and 100%), while ground granulated blast furnace slag (GGBS) (35% and 70% replacement level) and fly ash (25% and 50% replacement level) are adopted as the supplementary cementitious materials (SCMs). The results showed that EP is beneficial for improving the flow of fresh mortar, and soft mortar (flow diameter > 200 mm) can be produced by using EP in SCM-cement blends. Both EP and EV can be utilised to produce lightweight mortar in the density range of 1400–1700 kg/m3 and 900–1100 kg/m3 at 50% and 100% sand replacements, respectively. Although the lightweight aggregates resulted in compressive strength decrease, the developed lightweight mortar using 50% EP (with or without SCMs) can be classified as type N mortar (compressive strength exceeding 5.17 MPa) while those prepared with 100% EP as well as 50% EV can be categorised as type O mortar. Response surface methodology carried out in this study also demonstrated that the mathematical equations can suitably estimate the studied performances of the lightweight mortars.