<p>The continuous accumulation of high-titanium slag, a by-product of the metallurgical industry, presents a significant environmental concern. This study evaluates the feasibility of utilizing high-titanium slag coarse aggregate (HTSCA) as a sustainable substitute for natural coarse aggregate (NCA) in pumped concrete. Five concrete mixtures with HTSCA replacement levels ranging from 0 to 100% were prepared. The physical properties of HTSCA were tested, and its microstructure was analyzed via XRD and MIP, confirming its porous texture and high water absorption. A comprehensive evaluation before and after pumping was conducted on workability, rheology, mechanical performance, and microstructure. Results indicate that increasing HTSCA content reduced flowability and increased rheological resistance due to its rough surface texture and high water absorption. Moderate HTSCA replacement improved paste stability, whereas excessive replacement caused lubrication loss and pumping blockage. Pumping improved paste dispersion and densified the interfacial transition zone at lower replacement levels, thereby enhancing compressive strength. XRD analysis revealed no formation of new crystalline phases after pumping, but a slight narrowing of the amorphous hump suggested a reduced degree of C–S–H gel formation. An empirical lubrication index was proposed to characterize the relationship between effective paste availability and aggregate surface area, which correlated strongly with measured pumping pressure loss. An HTSCA substitution ratio below 50% was recommended to ensure well-balanced rheological properties, pumpability, and mechanical strength. These findings enhanced understanding of the flow behavior of concretes incorporating porous industrial by-product aggregates and support the design of pumpable sustainable mixtures.</p>