Effects of various sizes of cenospheres on microstructural, mechanical, and thermal properties of high-strength and lightweight cementitious composites

Abstract

Cenosphere is a key component as lightweight aggregates or supplementary cementitious materials to develop concrete with lightweight, high mechanical strength, and low thermal conductivity. Due to their wide size variation (10–600 μm) as industrial waste, it is necessary to understand the impact of different cenospheres on cement-based materials. This study aimed to reveal the mechanical, thermal, and microstructural properties, along with the chemical behaviors, of four different-sized cenospheres used in high-strength lightweight cementitious composites (HSLCCs). The results showed that cenospheres that have been distinguished from voids, displayed good uniform dispersion in the designed HSLCC samples according to microcomputed tomography (μ-CT) data. The HSLCCs exhibited considerable workability with achieving high-strength, lightweight, and low-thermal conductivity. The above properties of HSLCCs at 28 days were 61–94 MPa, 1.77–1.97 g/cm, and 0.83–1.04W/mK, respectively. Small size cenospheres and 10% dosage contributed to the higher compressive strength, while large size cenospheres and 20% dosage contributed to lower density and thermal conductivity. Chemical analysis indicated that the cenosphere particles mainly act as inert fillers which allowed to use cenospheres of all sizes studied herein for lightweight aggregate in high strength and lightweight cementitious composites.