The Effect of Expanded Glass and Expanded Clay Aggregate Additives on Water Vapor Diffusion Based on Wet Cup Method in Cementitious Lightweight Mortars for Sustainable Buildings

Water vapor permeability is the ability of a material to allow vapor (such as water vapor or any gas) to pass through it. Water vapor permeability also indicates the breathability of the material. Water vapor permeability in building materials is an important factor that ensures that moisture formed in the interior of a building section can pass to the outside and that no damage occurs inside due to moisture. Water vapor permeability in cement-based building materials varies as a function of the structural properties of the material, and depends on porosity, aggregate characteristics, density and thermal effects, especially in the matrix structure. It is known that lightweight mortar combinations obtained by using porous aggregates are more prone to water vapor transmission. However, the extent to which the type and general form of the aggregate used in mortar mix designs affect this property requires a detailed examination. In this context, a series of cement-based composite mortar designs were created with samples of expanded glass and expanded clay aggregates with two different characteristic properties and in addition to physical and mechanical analyses, water vapor permeability properties were also comparatively investigated with respect to the control mortar sample. In the mixture designs, 32% of expanded glass-expanded clay aggregates were used as lightweight aggregates. According to the study results, mixtures with expanded glass aggregates exhibited higher water vapor permeability properties than the test samples with expanded clay aggregates. Water vapor diffusion resistance coefficient values varied between 7.68 and 8.85 for the test samples with lightweight aggregates.