Development of strain-hardening lightweight engineered cementitious composites using hollow glass microspheres

Hollow glass microsphere (HGM) is a kind of ultra-lightweight inorganic non-metallic material with hollow structure, and it is a versatile and high-performance new lightweight material developed in recent years. HGMs comprising at least 45 wt% of recycled glass based on the total weight of a feed composition from which the hollow microspheres are derived. The purpose of this study is to develop high-performance lightweight engineered cementitious composites (LWECCs) using efficiently waste recycled HGMs as a lightweight filler substitute for sustainable construction. LWECC is a flowable type of lightweight fiber-reinforced concrete, which is able to illustrate strain-hardening behaviors rather than tension softening after an initial crack and possesses a tensile strain up to 6%; however, available lightweight fillers in LWECC exhibit more brittle behavior compared with normal weight engineered cementitious composite. In this study, three different types of HGMs are used as lightweight fillers with 0.25, 0.40, and 0.60 g/cm³ densities, and their effects on fresh and mechanical properties of LWECC have been investigated. HGMs fillers are replaced at 40 and 60% weight of fly ash in the control mix. To evaluate the strength of the LWECC, samples were cured for periods of 7 and 28 days and then tested for mechanical properties by compression test and three-point bending. Furthermore, the scanning electron microscopy, energy dispersive X-ray spectroscopy and morphological observations to confirm the dispersion of the lightweight filler have been captured.