Heshachanaa Rajanayagam

Inter-modular connections (IMCs) govern the structural performance, safety, seismic resilience, and reusability of steel modular buildings, yet the existing literature on advanced IMC systems remains fragmented and connection-specific. This paper presents a comparative review of nine research-stage advanced steel IMC systems benchmarked against VectorBloc, the only commercially deployed proprietary connector among the systems considered, selected through a transparent screening of 120 research articles drawn from Scopus, Web of Science, ScienceDirect, and Google Scholar, of which 60 were retained for detailed analysis based on predefined inclusion and exclusion criteria. The ten connections reviewed are the VectorBloc Registration Pin (commercial benchmark), friction rocking, Shape Memory Alloy (SMA) Bolt, Cruciform Plug-in, L-Shaped Bracket with Web Cut-Outs, H-Shaped Bracket, Mid-Depth Self-Locking Plug-in, corrugated web moment frame, post-tensioned rod with friction washer, and Omnidirectional Through-Plate Corner connections. As VectorBloc is a commercially available proprietary product rather than a research-stage connection, it is not directly compared with the other nine systems in this review; it is included solely to provide a qualitative commercial point of reference. Each of the nine research-stage systems are assessed on a like-for-like basis against eight criteria: structural capacity, seismic response, energy dissipation, fire performance, constructability, sustainability, reusability, and cost impact; VectorBloc is discussed against these same criteria qualitatively, as a reference point for current commercial practice, rather than ranked numerically alongside the nine. The comparison shows that SMA bolts and friction rocking connections excel in seismic resilience and self-centring, corrugated web connectors combine high energy dissipation with sustainability benefits, and VectorBloc’s commercial track record offers a useful benchmark for constructability and cost efficiency, although no single system performs best across all criteria. A multi-criteria design framework is proposed to guide future connection development and hybrid strategies, identifying fire performance, long-term durability, and reusability as the most significant research gaps for next-generation modular steel buildings.

The increasing generation of ceramic waste from manufacturing defects, construction activities, and demolition operations poses significant environmental and waste management challenges worldwide. This study presents a preliminary investigation into the incorporation of ceramic waste aggregates (CW) as partial and full replacement for natural coarse aggregates in fly ash-based geopolymer concrete (GPC) under water-curing conditions. Five mix compositions were prepared with ceramic waste aggregate replacement levels of 0%, 20%, 40%, 60%, and 100%. Fresh and hardened properties were evaluated using flow table and early-age compressive strength tests at 7 and 14 days. The 20% replacement mix achieved the best compressive strength value of 5.52 MPa at 14 days, slightly exceeding the control GPC mix (5.09 MPa) among the limited mixtures investigated in this preliminary study. However, higher replacement levels resulted in reduced compressive strength, which may be associated with increased porosity, weaker aggregate–matrix bonding, and limitations related to the adopted water-curing regime. Workability remained within acceptable flow ranges for most mixes, although reduced flowability was observed for the 40% replacement. The comparatively low strength values obtained across all mixtures may largely be associated with the absence of heat curing and the inclusion of additional water to improve workability, both of which likely limited the geopolymerization efficiency. Based on the comparatively low compressive strength values obtained, the investigated mixtures, in their current form, are only suitable for low-strength or non-structural applications rather than structural concrete applications. Overall, this study provides preliminary insights into the influence of ceramic waste coarse aggregates on the workability and early-age compressive strength behavior of fly ash-based geopolymer concrete under the adopted experimental conditions. Further optimization of the curing regimes, mix design parameters, and long-term mechanical and durability performance is necessary before broader engineering applicability can be established.