Recently, the recycling of waste glass has become a worldwide issue in the reduction of waste and energy consumption. Waste glass can be utilized in construction materials, and understanding its effects on material properties is crucial in developing advanced materials. In this study, recycled crushed and expanded glasses are used as lightweight aggregates for concrete, and their relation to the material characteristics and properties is investigated using several approaches. Lightweight concrete specimens containing only crushed and expanded waste glass as fine aggregates are produced, and their pore and structural characteristics are examined using image-based methods, such as scanning electron microscopy (SEM), X-ray computed tomography (CT), and automated image analysis (RapidAir). The thermal properties of the materials are measured using both Hot Disk and ISOMET devices to enhance measurement accuracy. Mechanical properties are also evaluated, and the correlation between material characteristics and properties is evaluated. As a control group, a concrete specimen with natural fine sand is prepared, and its characteristics are compared with those of the specimens containing crushed and expanded waste glass aggregates. The obtained results support the usability of crushed and expanded waste glass aggregates as alternative lightweight aggregates.

Foamed concrete contains numerous pores inside the material, and these pores are a significant factor determining the material characteristics. In particular, the pore distribution characteristics of foamed concrete significantly affect its thermal and mechanical properties. Therefore, an appropriate investigation is necessary for a more detailed understanding of foamed concrete. Here, a set of foamed concrete samples with different densities is used in order to investigate the density effects on the pore characteristics, as well as the physical properties of the materials. The pore distribution characteristics of these samples are investigated using an X-ray micro-computed tomography (micro-CT) imaging technique with probabilistic and quantitative methods. Using these methods, the anisotropy, the pore circularity factor and the relative density of cell thickness are examined. The thermal (thermal conductivity) and mechanical (directional modulus and strength) properties of each foamed specimen are computed using numerical simulations and compared with experimental results. From the obtained results, the effects of the pore sizes and shapes on the local and global properties of the foamed concrete are examined for developing advanced foamed concrete with lower thermal conductivity by minimizing the strength reduction.

This study presents the results of an experimental investigation of the effects of nanosilica (NS) on the strength development, transport properties, thermal conductivity, air-void, and pore characteristics of lightweight aggregate concrete (LWAC), with an oven-dry density 1 wt.%). NS contributed to compaction of the LWAC matrix and a modification of the air-void system, by increasing the amount of solid content and refining the fine pore structure, which translated to a noticeable improvement in mechanical and transport properties. On the other hand, NS decreased the consistency, while increasing the viscosity of the fresh mixture. An increment of superplasticizer (SP), along with a decrement of stabilizer (ST) dosages, are thus required.