Speaker
Description
Industrial Symbiosis through Secondary Gypsum Resources for Circular Construction
Diana Bajare1, Girts Bumanis1
e-mail: diana.bajare@rtu.lv
1 Riga Technical University, Faculty of Civil and Mechanical Engineering, Institute of Sustainable Building Materials and Engineering
Gypsum-containing waste is a valuable secondary resource that supports circular construction and reduces landfill disposal. Three circular gypsum streams were assessed: synthetic gypsum (SG), phosphogypsum (PG), and recycled plasterboard gypsum (RPG).
SG exhibits a considerably finer particle-size distribution than commercial gypsum (58–78% vs. ~4% below 63 μm). While this enables binder production at relatively low calcination temperatures (105–120 °C), excessive fineness may increase water demand and limit direct utilization in conventional gypsum products.1 PG consists predominantly of calcium sulfate dihydrate (D50 ≈ 74 μm; commercial gypsum ≈ 140 μm) and contains residual phosphorus compounds (P₂O₅ ≈ 0.6 wt.%), which may affect hydration kinetics and prolong setting times.² RPG exhibits the highest compositional variability due to differences in plasterboard composition and additives. Following calcination at 160–180 °C, RPG can be converted into a secondary gypsum binder, while high-temperature treatment (~700–800 °C) may provide a route to more uniform anhydrite binders.1
The suitability of SG, PG, and RPG as substitutes for natural gypsum was evaluated in commercial gypsum products with replacement levels ranging from 0 to 30 wt.%. Secondary gypsum resources were also incorporated into gypsum–cement–pozzolan (GCP) systems, achieving compressive strengths of up to 50 MPa after 28 days.2 These materials demonstrated potential for additive manufacturing applications, partly due to their favourable pore structure, as revealed by micro-computed tomography.2
The findings highlight the potential of secondary gypsum resources to contribute to circular construction by reducing reliance on virgin raw materials and promoting the valorization of industrial and construction waste streams.3,4
Keywords: secondary gypsum, synthetic gypsum, phosphogypsum, recycled plasterboard gypsum, industrial symbiosis, circular economy, sustainable construction.
References:
1. G. Bumanis, et.al, Processing of gypsum construction and demolition waste and properties of secondary gypsum binder, Recycling, 7 (2022) 30.
2. G. Sahmenko, et.al, Gypsum–cement–pozzolan composites for 3D printing: Properties and life cycle assessment, J. Compos. Sci., 8 (2024) 212.
3. G. Bumanis, et.al, Circular economy in practice: A literature review and case study of phosphogypsum use in cement, Recycling, 9 (2024) 63.
4. K. Weimann, et.al, Environmental evaluation of gypsum plasterboard recycling, Minerals, 11 (2021) 101.