Case Studies in Construction Materials (Dec 2024)
Sustainable utilization of feldspar powder from lithium extraction byproducts as road construction material
Abstract
In order to reduce the storage cost and avoid environmental hazards of feldspar powder waste from lithium extraction byproducts, this work investigated the feasibility of ordinary silicate cement-stabilized feldspar powder-lateritic clay (FP-LC) composite as road construction material. Firstly, preliminary mix design of the new material was conducted to determine the optimum moisture content and maximum dry density. Subsequently, the effects of ratio of FP to LC on the mechanical properties of the composite were investigated through unconfined compressive strength (UCS), California bearing ratio (CBR) and shear strength tests. Finally, the strength formation mechanism of the FP-LC mixture was analyzed in combination with SEM and XRD testing. The results indicate that the UCS after 14 d curing, CBR and cohesive strength of FP simply stabilized by 6 % cement is 0.95 MPa, 87.3 % and 140.64 kPa, respectively, which can meet the requirements for subgrade materials. The addition of LC significantly improves the mechanical properties of the composite. The mass ratio of 40 % FP to 60 % LC results in the optimal UCS after 14 d curing, CBR and cohesive strength with 1.6 MPa, 164.1 % and 250.16 kPa, respectively, which makes it applicable as subbase materials for medium-light traffic levels. The particle closest packing analysis and SEM and XRD characterization demonstrated that the enhancement of UCS, CBR and shear strength comes from compact arrangement of FP and LC particles and the bonding effect of cement hydration products between them. This work proposes an eco-friendly and sustainable utilization approach of feldspar powder from lithium extraction byproducts as road construction material, which are important to overcome the challenges of both waste management and resource shortage for new energy and highway industries, respectively.
