Search

As landslide-prone areas in remote mountainous areas, it can be challenging to implement tradition landslide monitoring methods such as station observation and satellite remote sensing due to difficulties in power supply and high installation costs. In order to address this issue, a self-powered sensor based on triboelectric nanogenerator (TENG) has been proposed for early warning of mountain landslides. The sensor is designed as a circular tube by utilizing polytetrafluoroethylene (PTFE) and aluminium (Al) as the friction layer of the sensing unit. By harnessing the magnetic forces both inside and outside the tube, the two friction layers are brought into contact and undergo relative sliding along with the movement of the magnet. The working principle of the sensor has been analyzed through COMSOL software simulation, and experiments have been conducted to determine the optimal width of the friction layer material. The novel structure and sensing mechanism of the internal TENG driven by the magnet material result in highly sensitive output signals for this self-powered sensor. At different relative sliding speeds and separation distances, the sensor shows a remarkable sensitivity, with an output voltage of 1.31 V and an output current of 0.17 μA at a relative sliding speed of 0.05 m/s. Laboratory simulations of landslides demonstrate that the TENG-based self-powered energy sensor achieves an output voltage of 2.5 V, effectively detecting the location of landslides. This study expands the development and application of TENG in the field of geological disaster monitoring, and provides a promising solution for the construction of self-powered sensors and self-drive systems. [ABSTRACT FROM AUTHOR]

To enhance the service performance of concrete dams in alpine regions, the effects of polyvinyl alcohol (PVA) modified waste rubber on the durability of cement-based composites were analyzed by the capillary absorption test, chloride ion resistance test, freeze-thaw test, and carbonation test. The effects of rubber particles with a volume fraction of 0-30% on the durability of cement-based composites were systematically evaluated before and after modifications by PVA solution with a mass fraction of 0.1%. The results showed that, when the volume fraction of rubber increases to 10%, the capillary water absorption, chloride ion penetration resistance, freeze-thaw resistance, and carbonization resistance of cement-based composites are all improved. After adding PVA, the adhesion between rubber particles and cement matrix is enhanced, especially when the integral number of rubber body is 10%, the cumulative pore volume decreases by 28. 8%, further improving the durability of rubber cement based composite materials. Research can provide new ideas for the further application of rubber concrete in engineering practice. [ABSTRACT FROM AUTHOR]

In order to improve the tensile properties of concrete, fiber materials are usually added into concrete to improve its mechanical properties. The internal strain fields in the external loaded fiber reinforced concrete are very complex, and it is still difficult to test them currently. In this paper, the X-ray microcomputed tomography (XCT) in situ three-point bending test is used to track the loading process of fiber mortar. The digital volume correlation ( DVC) is used to calculate the internal volume strain and the internal strain field of mortar with different fiber contents at different loading stages. The results show that adding fiber into concrete can improve the fracture performance of concrete, and the length, width and volume of crack are obviously reduced. The volumetric strain evolution of samples with different fiber content at different loading stages can be obtained by combining XCT with DVC. There is still non-negligible deformation energy consumption outside the fracture surface when samples fail. The internal deformation response of the specimen under load can be obtained by volume strain analysis. [ABSTRACT FROM AUTHOR]

In view of the influence of superabsorbent polymer (SAP) on the permeability and durability of concrete, by testing the content of chloride ions in concrete under salt water immersion-drying cycle and the carbonation depth under accelerated carbonation conditions, the effects of water pre-soaked SAP and 1% AgNO3 solution pre-soaked SAP gel-particles as internal curing agents on chloride ion invasion and carbonation property of the concrete specimens were investigated. Experiment results show that SAP and SAP-Ag particles play a role of water pump and chloride ion pump in concrete under the wet-dry cycle treatment to accelerate the accumulation and transport of Cl- in concrete, respectively. That is to say, SAP internal curing agent has a negative effect on the concrete resistance to chloride ion erosion under marine environment. On the other hand, by adding appropriate amount of SAP or SAP-Ag gel-particles, the capillary pores of concrete can be plugged to reduce the diffusion path of CO2, as the SAP gel-particles are swollen by moisture absorption, so that the carbonation resistance of concrete is improved to some extent. [ABSTRACT FROM AUTHOR]