Far back in the 18th century, the concept of glass being used as a major constituent in concrete blocks has not yet been idealized. Concrete blocks (consisting of cement, sand and water) were of high importance as they became a suitable alternative to fired clay bricks. Glass was only seen in building construction as a prominent element in the world of aesthetics because of its vitreous glazing appearance and illumination potential at night [1]–[3]. An in-depth investigation regarding the relationship between glass and concrete was undertaken in the year 1904 to explore the possible usefulness of glass in building construction [4]. Joachim, a French architect, building the first cupola of concrete and glass prompted Fredrick Keppler in 1907 to apply for a grant of ownership for the concept of solid glass blocks of 4 to 6.5cm to be fitted at support structures of reinforced concrete. This led to the development of hollow glass blocks for vertical structures which were concluded to be more advantageous in terms of noise and thermal isolation in comparison to solid blocks[5]. Subsequent years later, the advancement of glass instigated prominent researchers in the study of glass for paving stones as well as the partial replacement for fine aggregates, hence the name Glasscrete[6]. The success of this research recognizes glass aggregate as a formidable substitute. Despite the explorative progression of glasscrete over concrete, the issue of spalling for glasscrete blocks in buildings was left undiscussed.
According to [7], spalling is defined as those fragments or pieces or chips of concrete, brick or limestone which gradually come off over time. This defect occurs as the concrete is subject to corrosion, biological weathering and most especially, excess moisture that usually occurs through leakages in conduit pipes. Not only because spalling give an unsightly appearance on walls and paints, but it also causes structural damage if left untreated. Much research has been done on the introduction of various alternative materials in concrete for various positives on its properties but none has looked into the possibility of glass solving the problem of spalling in sandcrete blocks [8]–[15]. In this study, the water absorption property of glass is of significant interest in achieving the no-spalling effect of glasscrete blocks in building construction. Glasscrete blocks are masonry units (usually precast), consisting of cement and waste glass used as both fine and coarse aggregates with admixtures. These stated constituents are thoroughly mixed with water as its binder in the appropriate mix ratios [16]. Glasscrete materials are highly recognized for pavement and interlocking structures, but can also be used for both interior and exterior wall construction [17]. According to [18], solid and hollow blocks are the conventional classification of blocks. Therefore, the above classes can also be made with glasscrete materials. These categories of blocks are either produced by hand or by concrete mixer [19]. [20] reported that the shape and size of blocks can be determined by the moulds used. According to the Nigeria Industrial Standard, the moulds used for block production are fabricated using the millimetre or inches metric system of measurement. [21] proposed the sizes of blocks as 450mm x 225mm x 100mm, 450mm x 225mm x 150mm and 450mm x 225mm x 225mm. Remnants of glass materials produced around the world are usually creating huge piles on landfills [22]. Glass waste as a non-biodegradable material has contributed immensely to environmental pollution. Many researchers [23], [24] studied the productive use of waste glass. These investigations yielded positive results as waste glasses could be used as aggregates in concrete block production.