## 1 Introduction  
Composite structures gained popularity in the early twentieth century amongst structural engineers [1]. Composite floor slabs made of profiled sheets and concrete have gained greater acceptance. The sheeting is permanent formwork for concrete casting and provides the required tensile reinforcement after the concrete has hardened [2]. Modular construction is highly considered among industry professionals owing to its many advantages such as quality improvement, the enhancement of structural reliability, increased productivity and shortening of construction time, and reduced labour and waste. Likewise, these composite beams' stiffness and bending resistance provide a promising engineering solution. Several studies have investigated the performance of modular slabs by incorporating lightweight composite materials such as fibre-reinforced polymer (FRP), dry board or GFRP sandwich panels [3, 4]. These materials generally offer a higher load resistance, leading to increased strength; however, research on their performance in large-scale modular buildings is limited. This has led to the development of steel-concrete composites for the sustainable and efficient construction of modular flooring systems. New steel-concrete flooring systems have been developed to improve upon the performance of the standard modular flooring system [5]. These also consider Design for Deconstruction (DfD), a significant aspect of sustainability considerations in modular construction [6]. A new deconstructable composite floor system consists of steel framing,precast concrete planks, and clamping connectors. It is efficient due to conventional composite action and enables refabrication and the reuse of materials [6]. Another system developed for DfD included individual rectangular panels fabricated from thin-gauge steel top and bottom plates with a sandwiched grillage of cold-formed channels and topped with gypsum concrete [7]. The literature also reports double tee, void core slab, half slab, block and beam, sandwich panels and C-formed as the effective forms of precast slab systems [8; 9; 10; 11; 12; 13]. In the case of a double tee and void core slab, long spans ranging up to 20 m were studied. However, small-scale, and full-scale specimens of up to eight metres were adopted for the other types of precast slabs. There are limited studies on reinforced concrete composites compared to prestressed and precast slabs [11]. The available studies show that the weight of the floor and partition walls add to the two elements of the heaviest weight in a composite floor module. With an overall restriction on the general dimension and weight of the modules for lifting and transportation, these parameters prove to be critical for modular floor components. Further, these structural slab units do not offer flexibility in terms of geometric parameters such as the width and thickness of the panels, and the spacing, type and size of the sections. Hence, it is important to develop lightweight and resilient structural floor panels that can be designed for the specific needs of the modular unit. Even with these limitations, a higher volume of studies focusses on the development of steel-concrete infill systems [14], owing to the increase in compressive strength and increased panel stiffness delaying the buckling offered by these composite slabs [15]. Moreover, the profile sheeting provides support by acting as a formwork taking the self-weight of concrete under large spans, avoiding the need for temporary props [16; 17]. However, some studies identify that using conventional concrete as an infill material would negatively affect the sustainability aspect of the modular construction concept due to the high amount of carbon emissions associated with the production of Ordinary Portland Cement [18]. A sustainable solution to this is using alternative cementitious materials such as geopolymer concrete, made from fly ash, slag, and other industrial waste products, avoiding using conventional cement [19; 20].