DEVELOPMENT OF SUSTAINABLE BORON-ENRICHED GEOPOLYMERS FOR NEUTRON SHIELDING APPLICATIONS

Date

2026-1

Author

Livdumlu, Kaya Berk

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The growing use of nuclear technologies in energy production, medicine, and radioactive waste management has increased the demand for efficient and low-carbon neutron shielding materials. Although Ordinary Portland cement (OPC)-based concretes are widely used, they exhibit a high carbon footprint and limited compatibility with boron-bearing constituents. This study examines alkali-carbonate-activated, cement-free binders produced using boron mine wastewater (BMWW) as mixing water. A Ca(OH)?–Na?CO?–fly ash (CNF) system was synthesized using two industrial BMWW sources with contrasting chemistries: mildly basic Çamköy (pH ≈ 8.6) and acidic, high-ionic-strength Emet (pH ≈ 3.37). The influence of BMWW chemistry on fresh-state behavior, reaction products, pore structure, environmental safety, and neutron attenuation was evaluated using oscillatory rheology, compressive strength testing, XRD, FT-IR, TGA–DTG, MIP, TCLP, and neutron transmission measurements conducted under narrow-beam geometry with a ²³?Pu–Be source. Binders prepared with Emet BMWW exhibited delayed early structuration but developed a denser alkali-carbonate-activated C–(A)–S–H-type gel network at later ages, resulting in refined porosity and higher compressive strength compared with the tap-water reference. Boron was predominantly incorporated within the amorphous matrix, exhibiting diffusion-controlled release and compliance with TCLP limits. Neutron transmission measurements yielded an effective attenuation coefficient of 0.337 ± 0.01 cm?¹ for the Emet system, approximately 21% higher than the control.

Subject Keywords

Neutron shielding, Boron mine wastewater, Alkali-carbonate activation, Cement-free binder, Fly Ash

URI

https://hdl.handle.net/11511/118420

Collections

Graduate School of Natural and Applied Sciences, Thesis