The construction industry is characterized by high energy consumption and high carbon emissions. With growing concern about climate change, environmental protection is becoming increasingly important. In this paper, the whole construction process of prefabricated floor slab (PFS) is divided into three stages: production, transportation, and construction stages. Carbon emissions are calculated based on the life cycle assessment (LCA) method. A case study of PFS construction in Shaoxing city, China, was examined, and the calculation results were compared and evaluated with the traditional construction methods, which showed that in the production stage, carbon emissions increased due to mechanical operations during the prefabrication process. In the transportation stage, carbon emissions also increased due to the heavier prefabricated components during the transportation process. During the on-site construction stage, carbon emissions considerably decreased due to the lower hoisting frequency and less on-site pouring.
It is imperative to construct high-level, innovative and challenging courses in the teaching of colleges and universities. It is also of great significance to explore innovative teaching methods for improving students’ learning effect. In this paper, the course “Civil Engineering Construction” of a civil engineering major is taken as a reform example. In this teaching-innovation mode, guided by students’ moral education and students’ achievements, and the course platform is built in order to achieve the education concept of sustainable development and cultivate applied talents who can solve complex problems in civil engineering. In teaching practice, “Dual Platforms”, which combines course teaching platform and virtual simulation platform, is built mainly to expand the learning approaches. The “Three Educations” mode, which combines on-site education, classroom education, and mental health education, is established to improve the comprehensive quality of students. Comprehensive academic evaluation is carried out through “Four Reports”, including an open assignment report, special technical study report, BIM (building information modeling) technical work report, and final comprehensive written test report. Through studying this course, students not only master the knowledge of civil engineering construction, but also acquire knowledge-innovation ability, such as thesis publication, patent writing, discipline competition, and cultivating the craftsman spirit and social responsibility to abide by professional ethics in future work. This teaching innovation mode has been implemented for 12 years and achieved excellent results in cultivating students’ intelligent ability for sustainable development. It has been promoted in 14 courses, and has certain reference significance for engineering-course teaching.
Here we study the effects of nano clay and polypropylene fiber on the unconfined compression and splitting properties of lime soil. Through a series of unconfined compressive strength (UCS) tests and splitting strength (STS) tests, the mechanical properties of lime soil (LS), nano clay modified lime soil (NLS), fiber modified lime soil (FLS), nano clay and fiber composite modified lime soil (NFLS) are analyzed, and the volume calculation formula of each phase in NFLS is deduced. Nano clay content αn, porosity volume η and lime volume LVi as independent variables, and the prediction models of UCS and STS of NFLS were established. Furthermore, the microstructure of LS, NLS, FLS and NFLS was analyzed by scanning electron microscope (SEM). It can be concluded that (1) with the increase in nano clay content, the UCS and STS of LS and FLS gradually increase. With the increase in fiber content, the UCS of LS first increases and then decreases, while the UCS and STS of NLS and STS of LS increase with the increase in fiber content, and the optimal fiber content is 0.75%. (2) UCS and STS of NFLS and η/LVi meet the linear relationship. The empirical formulas of UCS and STS established in this paper have a prediction accuracy of less than 10%. The strength of NFLS can be predicted according to the dry density of the sample and the content of each component material. (3) Nano clay can fill the pores of LS and promote the pozzolanic reaction between lime and soil, while fiber mainly plays a reinforcing role in LS, so as to improve the UCS and STS of LS. In NFLS, nano clay can improve the interfacial properties between fiber and LS, so as to improve its UCS and STS. This study can provide a reference for the modification technology of lime soil.
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