Construction Technology of Deep Foundation Pit Support in Municipal Civil Engineering Foundation Construction

Municipal civil engineering is the key content of municipal construction,and the construction scale is usually large.The quality of the project plays an important role in the development of urban economy.Due to the rapid increase of high-rise buildings,skyscrapers and underground buildings,the construction technology of deep foundation pit support has gradually become an indispensable construction technology.Therefore,the selection of foundation pit support construction technology is crucial in ensuring that whether the foundation is firm and stable,and whether the subsequent construction activities can be carried out smoothly.In view of this,the article discusses the application of deep foundation pit support construction technology in municipal civil engineering,aiming to provide reference for subsequent projects.

CT Image-based Analysis on the Defect of Polypropylene Fiber Reinforced High-Strength Concrete at High Temperatures

With the application of X-ray computed tomography（CT） technology of C80 high-strength concrete with polypropylene fiber at elevated temperatures, the microscopic damage evolution process observation and image building could be obtained, based on the statistics theory and numerical analysis of the combination of concrete internal defects extension and evolution regularity of microscopic structure. The expermental results show that the defect rate has changed at different temperatures and can determine the concrete degradation threshold temperatures. Also, data analysis can help to establish the evolution equation between the defect rate and the effect of temperature damage, and identify that the addition of polypropylene fibers in the high strength concrete at high temperature can improve cracking resistance.

Assessment of Reusing Ferrochrome Slag Wastes in Mortar as SCMs

The demand for alternative cementitious materials is on the rise,as the cement causes huge energy consumption and produces greenhouse gas emission.Additionally,there is economic potential for the construction industry to reuse wastes as supplementary building materials.The purpose of this study is to evaluate the potential of utilizing ferrochrome slag wastes in mortar as supplementary cementitious materials (SCMs),thereby achieving this double-sided goal.Thus,the mechanical and physical properties of ferrochrome slag wastes were investigated to be used as admixtures in concrete production.Three different cement mortar specimens were prepared by replacing cement with ferrochrome slag in ratios of 0,30%,and 60% by mass and flexural and compressive strengths of the specimens were determined at the ages of 7,28,56,90,and 180 days.Also,the effects of the ferrochrome slag replacement ratio on workability,setting time and volume expansion were revealed.Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were also investigated to study the microstructural properties of the specimens containing ferrochrome slag.Based on the results,it is concluded that ferrochrome slag wastes have pozzolanic activity,therefore reusing them as SCMs in the cement and concrete industry is convenient.