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.
At present, the issue of carbon emissions from buildings has become a hot topic, and carbon emission reduction is also becoming a political and economic contest for countries. As a result, the government and researchers have gradually begun to attach great importance to the industrialization of low-carbon and energy-saving buildings. The rise of prefabricated buildings has promoted a major transformation of the construction methods in the construction industry, which is conducive to reducing the consumption of resources and energy, and of great significance in promoting the low-carbon emission reduction of industrial buildings. This article mainly studies the calculation model for carbon emissions of the three-stage life cycle of component production, logistics transportation, and on-site installation in the whole construction process of composite beams for prefabricated buildings. The construction of CG-2 composite beams in Fujian province, China, was taken as the example. Based on the life cycle assessment method, carbon emissions from the actual construction process of composite beams were evaluated, and that generated by the composite beam components during the transportation stage by using diesel, gasoline, and electric energy consumption methods were compared in detail. The results show that (1) the carbon emissions generated by composite beams during the production stage were relatively high, accounting for 80.8% of the total carbon emissions, while during the transport stage and installation stage, they only accounted for 7.6% and 11.6%, respectively; and (2) during the transportation stage with three different energy-consuming trucks, the carbon emissions from diesel fuel trucks were higher, reaching 186.05 kg, followed by gasoline trucks, which generated about 115.68 kg; electric trucks produced the lowest, only 12.24 kg.
Kaolin was used as an adsorbent to remove toxic graphene oxide (GO) from an aqueous solution. The adsorption properties and mechanism of GO by Kaolin were systematically studied by various characterization techniques and methods. The effects of pH, amount of absorbent, and initial concentration of GO on the adsorption of GO by Kaolin were studied in detail. The results show that the interaction between GO and Kaolin is realized by the O-C=O bond, and the adsorption of GO by Kaolin is a chemical adsorption process. Under the optimized conditions (pH=3, T=303 K, equilibrium time = 6 h, C0 = 60 mg·L-1), the removal rate of GO reached 97.1% (Kaolin=70 mg), and the adsorption capacity reached 45.3 mg·g-1 (Kaolin=50 mg). According to the experimental results, Kaolin may be a promising material, which can effectively eliminate GO from an aqueous solution. The results of this study provide key information about the migration and potential fate of GO in the natural environment.
To observe the effect of recycled sand and nano-clay on the improvement of the early strength of soil-cement (7d), 0%, 10%, 15% and 20% recycled sand were added. While maintaining a fixed moisture content of 30%, the ratios of each material are specified in terms of soil mass percentage. The shear strength of CSR (recycled sand blended soil-cement) was investigated by direct shear test and four groups of specimens (CSR-1, CSR-2, CSR-3 and CSR-4) were obtained. In addition, 8% nano-clay was added to four CSR groups to obtain the four groups of CSRN-1, CSRN-2, CSRN-3 and CSRN-4 (soil-cement mixed with recycled sand and nano-clay), which were also subjected to direct shear tests. A detailed analysis of the modification mechanism of soil-cement by recycled sand and nano-clay was carried out in combination with scanning electron microscopy (SEM) and IPP (ImagePro-Plus) software. The test results showed that: (1) CSR-3 has the highest shear strength due to the “concrete-like” effect of the incorporation of recycled sand. With the addition of 8% nano-clay, the overall shear strength of the cement was improved, with CSRN-2 having the best shear strength, thanks to the filling effect of the nano-clay and its high volcanic ash content. (2) When recycled sand and nano-clay were added to soil-cement, the improvement in shear strength was manifested in a more reasonable macroscopic internal structure distribution of soil-cement. (3) SEM test results showed that the shear strength was negatively correlated with the void ratio of its microstructure. The smaller the void ratio, the greater the shear strength. This shows that the use of reclaimed sand can improve the sustainable development of the environment, and at the same time, the new material of nano-clay has potential application value.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.