دانلود رایگان مقاله انگلیسی تولید بتن سبز با استفاده از ضایعات بازیافتی و فرآورده های جانبی - امرالد 2017

ABSTRACT

Purpose This paper advocates utilizing recycled material in concrete production to support the sustainability benefits of using demolition and industrial refuse as a replacement for aggregates and cement in traditional concrete mixes. Crushed concrete from demolition sites served as a replacement for fine and coarse aggregate in some of the mixes at various replacements ratios. In addition, ground granulated blast furnace slag, metakaolin, silica fume, and fly ash each served as a cement replacement for certain proportions of the cement content in the tested mixes at various replacement proportions. Design/methodology/approach Compression strength tests, permeability, and thermal expansion tests were performed on various mixes to compare their performance to that of traditional mixes with natural aggregate, and with no cement replacement. Findings The compressive strength results indicated the suitability of using such demolition recycled materials as replacements in producing green concrete without significantly hindering its mechanical characteristics. In addition, the results indicated an enhancement in the mechanical characteristics of green concrete when replacing cement with pozzolanic industrial refuse and by-products. Originality/value This research investigates the sustainability benefits of using demolition and industrial refuse as a replacement for aggregates and reducing cement content in traditional concrete mixes.

CONCLUSIONS

Experimental work done in this research investigated the effect of industrial refuse and by products (as substitution of cement or aggregate) on the physical-mechanical properties of green concrete produced. This research results indicated a positive effect on compressive strength when cement was partially replaced with pozzolanic industrial refuse and byproducts locally available and produced in mass quantities in Egypt. Further, the research is concerned with the usage of demolition refuse to be recycled and used as a replacement for natural fine and coarse aggregates. The major research findings are: a) Regarding coarse aggregate partial replacement:
It was found that using crushed concrete as coarse aggregates replacement with ratios up to 50% enhances the compressive strength of mixes with cement content not greater than 350 kg/m3 (21.85 lb/ft3 ) by more than 30%, which is a very promising ratio.
However, when used in high cement content mixes (i.e. cement content = 450 kg/cm2 (6401 psi) it is not recommended to increase the percentage of replacement greater than 25%. Therefore, it is practical to use recycled concrete aggregate which is produced by recycled crushed concrete refuse in order to reduce the consumption of natural aggregate and the amount of concrete refuse which eventually ends up in landfills. b) Utilizing demolition refuse as a replacement for fine aggregates is not recommended as their use reduces the compressive strength of concrete mix by more than 10%. This research did not assess the interaction between concrete mixtures and reinforcement, which is recommended for future research. Other future research aspects should include the assessment of utilizing plastic refuse as an aggregate replacement.