Limestone calcined clay cement (LC³) presents a promising alternative material due to its reduced CO₂ emissions and superior mechanical properties compared to traditional Portland cement (PC). This study investigates the synergistic effect of calcined coal-series kaolinite (CCK) and limestone (LS) on the hydration behavior of cement, specifically focusing on varying mass ratios. The combination of CCK and LS promotes the formation of strätlingite and carboaluminates, which enhances early-age strength development. Additionally, the inclusion of CCK facilitates the formation of carboaluminates during later stages of hydration. After 56 days of hydration, the content of carboaluminates is over 10%wt. This stimulation of secondary hydration products significantly refines the evolution of pore structure, with the harmful large pores gradually transformed into harmless medium pores and gel pores, leading to marked improvements in compressive strength from 7 to 28 days. Replacing 45% PC with CCK and LS at mass ratio of 7 to 2, the compressive strength of blends reaches 47.2 MPa at 28 days. Overall, the synergistic interaction between CCK and LS presents unique opportunities to minimize the CO₂ footprint of the cement industry without compromising early and long-term performance.

In this paper, the possibility of retreated lithium slag (RTLS) with a high content of alkali, sulfate and fluoride as a partial replacement for fly ash (FA) to produce autoclaved aerated concrete (AAC) was investigated. The influence of the RTLS dosage on the AAC performance were examined. The composition and microstructure of hydrates as well as the microstructure of the RTLS-FA-based AAC compositions were determined by XRD, FTIR, TG-DSC and SEM. The results illustrated that the incorporation of RTLS changed the crystal structure and the microstructure of the tobermorite. With increased RTLS contents, the morphology of tobermorite was changed, and the grass-like tobermorite gradually transformed into network-like tobermorite. The newly formed tobermorite improved the mechanical performance of the AAC. Compared with the RTLS10, the content of tobermorite in the RTLS30 increased by 8.6%.

This paper investigates the structural transformation of dicalcium silicate (C₂S) crystals brought about through boron doping. Both qualitative and quantitative analyses were conducted to explore the correspondence between boron content and the structure of dicalcium silicate. The results show that boron doping can stabilize β-C₂S and the high-temperature phase α′_H-C₂S, and the structural transformation does not involve the modulation of α′_L-C₂S. There is a corresponding relationship between the unit cells of β-C₂S and α′_H-C₂S, which can be transformed using a transformation matrix. The relationship between boron content and the content of different C₂S structures, as well as the structural expressions for β-C₂S and α′_H-C₂S, is determined using linear fitting and multivariable linear regression analysis.

Alite calcium sulfoaluminate (ACSA) cement is an innovative and environmentally friendly cement compared to ordinary Portland cement (OPC). The synthesis and hydration of ACSA clinkers doped with gradient sulfur were investigated. The clinker compositions and hydrated pastes were characterized by X-ray diffraction (XRD), isothermal calorimetry, mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) to analyze its mineral contents, hydration products, heat release, pore structure, and microstructure. The compressive strength and linear expansion of ACSA mortars were tested for their mechanical properties. Results showed that clinkers doped with 2 wt.% MgO can offset the hurdle that SO₃ caused to the formation of C₃S (tricalcium silicate). Clinkers with varying ratios of C₃S and C₄A₃$ (calcium sulfoaluminate) were obtained, achieving 58–70% C₃S and 2.0–5.6% C₄A₃$ in ACSA through adjusting the KH (lime saturation factor) values and SO₃ dosage. ACSA cement showed better early mechanical properties. The 0.93 KH value with 3% SO₃ dosage in the raw meal, which contains 63.9% C₃S and 2.98% C₄A₃$ in the clinker, reached an optimal compressive strength level at 1d (26.35 MPa) and at 3d (39.41 MPa), marking 30.45% and 18.70% increases compared to PII 52.5. The excellent early strength of ACSA cement may offer promising applications t increasing the incorporation of supplementary cementitious materials, thereby reduce pollution and carbon emissions.

Zeolite Socony Mobil-5 (ZSM-5) is a commonly spent catalyst in the petrochemical industry; and phosphogypsum (PG) is a kind of industrial waste produced in the process of phosphoric acid production. The environmental issues caused by these two solid wastes are urgent and thus sustainable methodologies are required to dispose of and reutilize them. In this research, the waste ZSM-5 and waste PG were used to prepare a novel autoclaved aerated concrete. The effects of the different contents of disused ZSM-5 on the microstructures and performance of the PG-based AAC were determined. The results showed that the compressive strength and bulk density of the DZ4 sample were 2.6 MPa and 520 kg/m³, respectively. This study provides a novel and green approach to the reutilization of both waste PG and spent ZSM-5.