As a new type of green inorganic material, geopolymers have excellent mechanical properties, durability, and less environmental pollution. It is considered a new building material that can replace cement, but it also has some disadvantages such as high viscosity, poor fluidity, and more apparent pores after hardening. In this study, the uniaxial compressive strength test of geopolymer mortar was carried out, and the effects of alkali equivalent, alkali activator modulus, bone glue ratio, and silica fume content on the mechanical properties of geopolymer mortar were analyzed. The test results show that when the alkali equivalent is 13%, the alkali activator modulus is 1.4, the bone glue ratio is 2.0, the silicon powder content is 8%, and the metakaolin-based geopolymer mortar has higher uniaxial compressive strength. Through the comparative test of adding different kinds of defoamers and dosage, the effect of defoamers on the compressive strength, fluidity, density, and water-absorption of geopolymer mortar was further studied. The fluidity, density, and water-absorption were improved, and the uniaxial compressive strength was reduced. The formation of cementitious material in the mortar was confirmed by scanning electron microscope (SEM) observation. It was found that the pore structure and pore distribution changed with the content of different defoaming agents, and the microstructure of mortar after defoaming agent material treatment was shown. The proportion and distribution of Na, Al, and Si atoms were analyzed by energy dispersive spectroscopy (EDS). This experimental study shows that the defoamer can be an effective additive for geopolymer mortar.

Monitoring steep slopes in mountainous canyon areas has always been a challenging problem, especially during the construction of large hydropower projects. Effective monitoring is crucial for construction safety and operational security. However, under complex terrain conditions, existing monitoring methods have significant limitations and cannot comprehensively and accurately cover steep slopes. To address the above challenges, this study proposes a multi-temporal UAV-based photogrammetric offset tracking (POT) monitoring method assisted by terrestrial laser scanning (TLS), which is primarily applicable to rocky and texture-rich steep slopes. This method utilizes TLS point cloud data to provide supplementary ground control points (TLS-GCPs) for UAV image modeling, effectively overcoming the difficulty of deploying conventional RTK ground control points (RTK-GCPs) on high and steep slopes, thereby significantly improving the accuracy of UAV-based Structure-from-Motion (SfM) models. In a case study at a hydropower station, we employed TLS-assisted UAV modeling to produce high-precision UAV images. Using POT technology, we successfully identified signs of slope deformation between January 2024 and December 2024. Comparative experiments with traditional algorithms demonstrated that in areas where RTK-GCPs cannot be deployed, this method greatly enhances UAV modeling accuracy, fully meeting the monitoring requirements for steep slopes in complex terrains.