Lightweight high-strength concrete with the use of waste cenosphere as fine aggregate

Résumé

Cenosphere is a coal combustion by-product that presents interesting properties to be used in the production
of cementitious materials, such as hollow structure, low density, low thermal conductivity and notably thermal
stability. In addition, it displays pozzolanic reactivity under thermal curing. However, the cenosphere
potential for the development of unique construction materials has not been fully investigated, remaining
obscure for both power plants and the construction field. This study investigated the employment of waste
cenosphere in partial substitution to sand for the obtainment of high-strength lightweight concrete materials.
Cenosphere from a Brazilian power plant was chemically and physically characterized and the feasibility of
its use in concretes was investigated. It was discovered that the power plant’s fly ash is composed of approximately
0.2% of cenosphere. In addition, the cenosphere displayed size ranging from 30 to 300 μm and were
suitable for use as fine aggregate in concrete. Concrete with 33, 67, and 100% fine aggregate replacement by
the waste cenosphere was produced. Cenosphere-based high strength concrete presented strength higher than
70 MPa and density as low as 1500 kg · m-3. Compared to mixes of reference, cenosphere application as fine
aggregate improved the specific strength of high-strength concrete while maintaining equivalent mechanical
properties.
Keywords: waste material; cenosphere; high strength concrete; lightweight cementitious materials.