Development of sustainable fiber-reinforced high-performance cementitious composite using desert sand and assessment of economic and environmental impacts

Desert sand (DS) has great potential as a sustainable building material to alleviate the depletion of river sand (RS) resources. This study developed a sustainable high-performance cementitious composite (HPCC) by substituting RS with DS, investigating its mechanical properties, hydration processes, and microstructural characteristics under reinforcement with steel fibers (SF) and polypropylene fibers (PPF). The results demonstrated that the smooth and regular morphology of DS particles improved the workability of fresh concrete but simultaneously increased interfacial porosity and promoted microcrack development at the aggregate–matrix interface, resulting in reduced compressive strength. The high elastic modulus and tensile strength of SF effectively compensated for this strength loss, with the 28-day compressive strength decreasing by only 2.44% (100.97 MPa) at a 50% DS replacement ratio. XRD and TGA analyses revealed that the filling effect and heterogeneous nucleation induced by DS promoted the formation of hydration products during the early hydration stage. An appropriate DS replacement ratio optimized the pore-size distribution of pores smaller than 0.1 μm, whereas higher replacement levels increased the proportion of capillary pores and interfacial defects. Furthermore, the Material Sustainability Index (MSI) assessment indicated that increasing the DS replacement ratio reduced the raw material cost of HPCC, whereas its carbon-saving benefit was strongly constrained by aggregate transportation distance. Considering the mechanical performance, resource utilization, and economic benefits comprehensively, the combination of 50% DS and SF exhibited the best overall performance. This study provides a feasible basis for the sustainable utilization of DS in HPCC.