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This paper introduces a new type of gypsum-based humidity-control material. The material combines gypsum–silica gel humidity-control material with 20% sepiolite powder activated by calcium chloride. Both experimental and simulation studies were conducted to assess its humidity-control performance. The experimental results indicate that gypsum-based humidity-control material has the property of absorbing moisture in high-humidity environments and releasing moisture in low-humidity environments. Moreover, both environmental temperature and relative humidity (RH) have an impact on the material's humidity-control performance. At a relative humidity of 97.4%, the maximum equilibrium moisture content of the material is 0.225 g/g, which is 1.4 times that of the gypsum–silica gel humidity-control material and 4.5 times that of pure gypsum material. The simulation results indicate that gypsum-based humidity-control material effectively mitigates indoor relative humidity fluctuations and maintains indoor air relative humidity within a narrow range. Furthermore, the material has the potential to reduce building energy consumption. This is especially evident under climate conditions with large temperature and relative humidity differences between day and night, such as in Beijing, Paris, and Atlanta. The maximum potential energy-saving rate in Beijing can reach up to 19.31%. [ABSTRACT FROM AUTHOR]

The Pile-beam-arch (PBA) method is a new and effective construction method for the urban metro station. It is the key to ensuring the safe construction of the station to clarify the influence of PBA method construction on surface deformation under unfavorable geological and large span conditions. Based on a station of Beijing subway, this paper studies the surface deformation law of the large-span PBA method in different construction stages under silty clay–pebble composite stratum by means of FLAC 3D numerical analysis and field monitoring of level. Then the influence of the excavation scheme of the pilot tunnel and the construction scheme of the secondary lining of the arch on the surface deformation is simulated and analyzed. The results show that, through numerical simulation, the ratio of pilot tunnel excavation: pile-beam construction: vault initial support construction: vault secondary lining construction is about 5:1.1:3.3:0.6. The settlement deformation mainly occurs in the excavation stage of the pilot tunnel. Through the comparative analysis of the field monitoring results and the numerical simulation results, it can be seen that the two results are highly consistent, which verifies the accuracy of the numerical simulation results. The pilot tunnel excavation scheme of excavating the middle first and then excavating both sides, first through the upper layer and then through the lower layer, and the scheme of one-time construction of the secondary lining of the arch are better. The research results promote the further maturity and perfection of large-span PBA method construction under unfavorable geology and provide reference for similar projects. [ABSTRACT FROM AUTHOR]

The river sand in the Santo Tomas River area of the Philippines is a kind of volcanogenic sand. The sand is fine sand with a fineness modulus of 2.2, an apparent density of 2380 kg/m3, a bulk density of 1320 kg/m3, a mud content of 6.7%, a methylene blue value of 1.2, a soluble chloride ion content of 0.00071%, and a light-matter content of up to 12.2%, which does not meet the requirements of the three-zone grading. Based on a series of experiments, this paper systematically studies and compares the workability, mechanical properties, and durability of two kinds of concrete with the river sand in the Santo Tomas River area and natural river sand in Beijing, China as fine aggregates, respectively. In addition, volcanogenic sand in the Philippines is technically optimized for the purpose of in-depth study. After optimization, such sand reaches the standard of Zone II-graded medium sand and is comprehensively improved in performance, which is evidenced by a fineness modulus of 2.4, an apparent density of 2570 kg/m3, a bulk density of 1550 kg/m3, a light-matter content of 6.0%, and a mud content of 6.7%. Study results show that in terms of mechanical properties, the concrete made of the optimized river sand in the Santo Tomas River area is superior to that made from the natural river sand in the Beijing area. In addition, separated light matter can be used as a natural light aggregate, which has a bulk density of 960 kg/m3, a cylindrical compressive strength of 2.5 MPa, and a 1 h water absorption of 8.2%, respectively. [ABSTRACT FROM AUTHOR]