Industrial solid waste is characterized by complex mineral phases and various components. Low-carbon cementitious materials can be prepared through precise regulation based on the material composition and properties of various industrial solid wastes. In this study, electrolytic manganese residue (EMR), carbide slag (CS), and granulated blast-furnace slag (GBFS) were used as alternatives to cement to prepare multicomponent solid waste cementitious materials. The effects of the proportions of EMR and CS on the cementitious activity of GBFS and the activation mechanism of alkali and sulfur were studied. The results showed that with increasing EMR content, the strength first increased and then decreased. At a GBFS content of 20%, CS content of 2%, and EMR content of 8%, the compressive strength was highest, reaching 45.5 MPa after 28 days of curing, mainly because the OH⁻ in CS and SO₄²⁻ in EMR synergistically stimulated the active components in GBFS. Hydrated products such as ettringite and hydrated calcium silicate (C–S–H gel) were generated and interlaced with each other to improve the densification of the mortar. Overall, the proposed system provides an avenue to reduce or replace the production of cement clinker and achieve the high-value-added utilization of industrial solid waste.

Poor utilization of ceramic polishing slag and uneven foaming at high temperatures are some of the crucial problems associated with the formation of porous ceramics. To overcome this, the present study was designed to prepare closed-ended polishing slag porous ceramics by controlling the holding time. Scanning electron microscope, XRD, and X-CT were used to investigate the effects of holding time on the microstructure, pore structure, and phase composition of porous ceramics. The results showed that the holding time had a great influence on the physical properties of the samples, and it provides uniform porosity without significant change in the composition of the material phase of the porous ceramics. Under a holding time of 30 min, volume density reached up to 0.68 g/cm³, while the water absorption and the apparent porosity were 27.33% and 15.49%, respectively. The compressive strength reached 13.07 MPa, and the pore size distribution is mainly between 25 μm and 100 μm, of which the d30 pore diameter accounted for about 28%, the d50 pore diameter accounted for 25%, the d70 pore diameter accounted for 12%, and the d90 pore diameter accounted for 10% of the pore size distribution. In conclusion, the present study clearly shows that the pore structure and properties of porous ceramics can be effectively controlled by controlling the holding time while using a high volume of polishing slag. The feasibility of X-CT for studying the pore distribution inside porous ceramics was verified.

In this paper, a new method of basic oxygen furnace (BOF) slag component modification with a regulator was studied. The main mineral was designed as C₄AF, C₂S and C₃S in modified BOF slag, and the batching method, mineral compositions, hydration rate, activation index and capability of resisting sulfate corrode also were studied. XRD, BEI and EDS were used to characterize the mineral formation, and SEM was used to study the morphology of hydration products. The results show that most inert phase in BOF slag can be converted into active minerals of C₄AF and C₂S through reasonable batching calculation and the amount of regulating agent. The formation of C₄AF and C₂S in modified BOF slag is better, and a small amount of MgO is embedded in the white intermediate phase, but C₃S is not detected. With the increase in the CaO/SiO₂ ratio in raw materials, the CaO/SiO₂ ratio of calcium silicate minerals in modified BOF slag increases, the contents of f-CaO are less than 1.0%, and the activity index improves. Compared with the BOF slag, the activity index and exothermic rate of modified BOF slag improved obviously, and the activity index of 90 days is close to 100%. With the increase in modified BOF slag B cement, the flexural strength decrease; however, the capability of resisting sulfate corrode is improved due to the constant formation of a short rod-like shape ettringite in Na₂SO₄ solution and the improvement of the structure densification of the hydration products.

Basic oxygen furnace (BOF) slag is a main byproduct produced during the converter steelmaking process. The poor grindability of BOF slag limits its added-value application. In this paper, the grinding characteristics of unmodified and reconstructed BOF slag were compared. Additionally, the grinding property of reconstructed steel slag was also studied after SiC foaming. The results show that the solid solution of divalent metal oxides’ RO phase, considered as the hardly grinding phase, discomposes after lime-bauxite reconstruction. The characteristics of BOF slag were tested through particle size analysis, XRD, SEM and MIP. The SSA (specific suface area) and the particle diameter of unmodified BOF slag could reach 303.1 m²/kg and 51.75 µm after 10 min of grinding, but that of reconstructed BOF slag could reach 354.5 m²/kg and 18.16 µm after the same grinding time, respectively. The grinding efficiency of steel slag was obviously increased and the particle characteristics were improved after foaming modification. BOF formed as a porous structure after SiC foaming; its porosity, SSA, and particle diameter can reach 31.79%, 424.4 m²/kg, and 24.36 μm and increased by 10.31%, 19.72%, and 39.04%, compared with the reconstructed steel slag of undoped foaming agent, respectively, and the grindability was further improved. A theoretical basis for large-scale BOF slag utilization is provided.

In this study, the reduction of the early-age strength of mortar caused by the traditional super absorbent polymer (SAP) was solved. Two types of alkanolamines (Alkanolamine-A and alkanolamine-B) and calcium nitrite were compounded with traditional SAP as early-age strength components and then were added into the mortar to evaluate effects on early-age strength and drying shrinkage. Results showed that adding two types of alkanolamines could significantly improve the early-age compressive strength of mortar. The addition of alkanolamines could refine the pore of cement paste and reduce the average pore size, which can be reflected by the increased strength and improved mortar drying shrinkage. Among them, the mortar with the composite of alkanolamine-A and alkanolamine-B added showed excellent performance. Its mechanical properties increased to 129% at day 3 and 139% at day 7 compared with the reference group; compressive strength can reach up to 31.8 MPa. The average pore size of the cement paste decreased by 27.8%, and the drying shrinkage was significantly smaller compared with the reference group.