JOURNAL OF MATERIALS & CONSTRUCTION

Effect of moisture content on printability, deformation, and drying shrinkage of extrusion-based 3D-printed white clay ceramics

Nguyen Quynh Nguyen — 2026-05-20

This work studies the role of moisture content in extrusion-based 3D printing of white clay. The clay used in this study is a kaolinite-rich aluminosilicate material, with SiO₂ and Al₂O₃ as the main oxides. Different moisture levels were prepared to examine how the paste changes during deformation testing, extrusion, and drying. At 25% moisture, the clay still behaved as a plastic body, with a deformation ratio of about 0.26. However, the paste was rather stiff under these conditions and did not feed smoothly during printing. When the moisture content was increased to about 30-35%, extrusion became more stable, as the paste could pass through the nozzle more easily. At higher moisture content, close to 38%, the material flowed better, but the printed bars became more sensitive to drying deformation. After drying at 60°C, the average shrinkage of the printed bars was about 9.79%. Warping, surface wrinkling, and small cracks were also observed, especially in samples with higher moisture content. The results show that moisture content has to be carefully controlled because it improves flowability but may reduce shape stability after printing. For the present clay system, a moisture range of about 30-35% appears to be a practical starting point for extrusion-based ceramic printing.

Recent advances in 3D printing with waste sludge and recycled construction materials

Nguyen Thanh Van — 2026-05-20

This paper reviews recent studies on extrusion-based 3D printing that use waste sludge and recycled construction materials in printable cementitious mixtures. The reviewed materials include construction and demolition waste, recycled fine aggregates, steel slag, alkali-activated slag, mining tailings, river-sediment sludge, recycled plastic particles, and waste-based geopolymer binders. These materials do not behave in the same way in printing systems. Recycled aggregates, for example, often increase yield stress and improve buildability, but high replacement levels can make extrusion less stable and may reduce mechanical performance. Slag-based binders and geopolymer systems can reduce Portland cement consumption, though their setting behavior and rheology still require careful control. Sludge-derived lightweight aggregates and recycled plastic particles have also been tested in printable mixtures, but their use often requires adjustments to grading, water demand, and binder content. Across the studies reviewed, the main difficulties remain rheology control, interlayer bonding, shrinkage, anisotropic mechanical properties, durability, and the lack of standardized testing methods. These findings suggest that waste-based materials can support more sustainable 3D printing in construction, but their practical use depends on careful mix design and better control of fresh-state behavior.

Barriers to and drivers of construction e-bidding adoption: A TOE-based structured scoping review with implications for Vietnam

Nguyen Thi Thu Hien — 2026-05-20

Construction e-bidding has become an increasingly important component of the digital transformation of public procurement. In the construction sector, however, the existing literature remains fragmented, with most studies examining benefits, barriers, or implementation conditions separately within specific national or organizational contexts. There remains a lack of structured scoping reviews that focus specifically on construction e-bidding and organize the evidence through an organizational-level analytical framework. To address this gap, this study conducts a structured scoping review combined with content analysis, using the Technology-Organization-Environment (TOE) framework to systematize the factors influencing the adoption and implementation of construction e-bidding. Data were collected from Web of Science, Scopus, Google Scholar, and selected Vietnamese academic journals. After screening 253 initial records, 38 studies meeting the inclusion criteria were retained for analysis. The findings identify 24 recurrent factors, including 9 drivers and 15 barriers. Digital infrastructure, information security, system compatibility, and data standardization are found to be necessary enabling conditions. In developing economies, however, human resource capacity, top management commitment, organizational inertia, compliance pressure, transparency requirements, trust in the system, and relationship-based business practices appear to exert stronger influence on adoption and operational effectiveness. Based on these findings, the paper proposes a conceptual framework for future empirical research and discusses policy implications for improving the operation of Vietnam’s National E-Procurement System.