Low carbon ferrochrome slag (LCFS) is the metallurgical waste slag from the carbon ferrochrome alloy smelting process. Compared with high carbon ferrochrome slag, LCFS has great potential as cementitious material; the chemical compositions of the two types of slag are quite different. In this research, composite cementitious materials are prepared which use low carbon ferrochrome slag and granulated blast furnace slag (GBFS) as the main raw material. Steel slag mud (SSM) and flue gas desulfurization gypsum (FGDG) are used as the activator. In order to find the variety rule of compressive strength on the composite cementitious materials, a three-factor three-level Box-Behnken design is used to discuss the following independent variables: LCFS content, GBFS content, and water-binder ratio. Moreover, the hydration characteristics of the LCFS-GBFS composite cementitious materials is studied in this paper in terms of hydration product, micromorphology, and hydration degree, based on multi-technical microstructural characterizations. The results show that the compressive strength of the LCFS-GBFS composite cementitious materials is significantly affected by single factors and the interaction of two factors. The mechanical property of the mortar samples at 3, 7, and 28 days are 26.6, 35.3, and 42.7 MPa, respectively, when the LCFS-GBFS-SSM-FGDG ratio is 3:5:1:1 and the water-binder ratio is 0.3. The hydration products of LCFS-GBFS composite cementitious materials are mainly amorphous gels (C-S-H gel), ettringite, and Ca(OH)₂. With the increase of LCFS content, more hydration products are generated, and the microstructure of the cementitious system becomes more compact, which contributes to the compressive strength. The results of this research can provide a preliminary theoretical foundation for the development of LCFS-GBFS composite cementitious materials and promote the feasibility of its application in the construction industry. Deep hydration mechanism analysis and engineering applications should be studied in the future.

The high dimensionality of the modern remote sensing data of construction land makes it complicated to extract image data. This paper proposes a dimensionality reduction and extraction strategy for the remote sensing data of construction land, with the aid of building information modeling (BIM) and geographical information system (GIS). Firstly, the BIM was employed to reduce the size of the remote sensing data of construction land and to obtain the information of each element. Next, the remote sensing data of construction land were parsed, and the key BIM elements were extracted through semantic filtering. In addition, the remote sensing data were converted into a triangulated irregular network (TIN), which can be processed by the geographical information system (GIS). In the end, random projection was utilized to reduce the dimensionality and compress the remote sensing data, and realize the data extraction. Experimental results show that our approach can compress and extract the information from construction land images in the remote sensing data with a high accuracy.

This paper proposed a wedge concrete fixed pier device based on self-locking to solve the problems existing in the fixed pier of water supply pipeline in utility tunnels. The system converted the horizontal thrust, originally applied to the weld seam...

For water purification plants and sewage treatment plants, there is no reference optimal steel content for the wall of reinforced concrete water pool. Focusing on the reinforced concrete water pool, this paper explores the optimal wall thickness and optimal reinforcement area at different bending moments and identifies the optimal steel content. To solve the problem, the authors established the discrete distribution function for the engineering cost per unit length of pool wall and steel content. The theoretical model was verified by numerous data through Excel numerical simulation. The research results provide a reference optimal steel content for designers and help to save the engineering cost of pool wall.