Abstract: To address the challenges associated with the disposal and low resource utilization rate of fine particles generated
from wet-process manufactured sand production,this study proposes thinking for preparing unfired bricks using manufactured
sand fine particles,aiming to achieve solid waste resource utilization and develop novel green building materials. Unfired
brick specimens were fabricated using manufactured sand fine particles and P. O 52. 5 Portland cement as primary raw materials
through hydraulic forming and standard curing processes. The influence of fine particle content on the physical and mechanical
properties of the bricks was systematically investigated. Microscopic analysis techniques,including XRD and SEM,were
employed to elucidate the performance enhancement mechanism. Furthermore,the effect of Fe2O3 content on frost resistance
was evaluated through freeze-thaw cycle tests. The results indicate that the optimal comprehensive performance is achieved at a
fine particle content of 50%. The unfired bricks exhibit a 28 d compressive strength of 23. 98 MPa,a density of 2 238. 06
kg/ m3,a water absorption rate of 3. 67%,and a softening coefficient of 97. 10%. All performance indicators meet the requirements
of the MU20 grade specified in the Non-sintered waste tailings brick (JC/ T 422—2024) standard. Microscopic analysis
reveals that at this optimal mix ratio,hydration products form a dense C-S-H gel network,effectively encapsulating the fine
particles and creating a rigid skeleton. Freeze-thaw cycle tests demonstrate that the frost resistance of the unfired bricks improves
significantly with increasing Fe2O3 content. This study confirms the technical feasibility of preparing frost resistant unfired
bricks with a high content of manufactured sand fine particles,providing a scientific basis for solid waste resource utilization
in the aggregate industry.