fib Symposium 2022
Anna Perepechay, Saverio Spadea, Tom Dyer & Vasant Matsagar
Rendered image of a curved concrete beam
In recent years, significant steps have been taken towards the design of sustainable cementitious-based materials, mainly by promoting industrial and/or natural by-products in partial substitution of Portland Cement (PC). The design of concrete mix should be, however, tailored to the specificity of the application, which may incorporate additional features aimed at reducing the impact of construction material on the environment. Recent research by the authors has focused on the valorisation of natural fibres obtained from crop varieties wildly available in India, which are generally fated to incineration and are therefore cause of considerable pollution. The overall aim is to use waste fibres combined with mortar to improve the mechanical and durability properties of both fibres and cement-based material. An experimental investigation has focused on the influence of partial cement replacement on the mechanical properties of different mixes in compliance with EN 196 standard. These are preliminary tests on mortar matrices aimed at designing sustainable concrete. Binary and ternary mixes were obtained by varying the content of ground granulated blast-furnace slag (GGBS) and/or-limestone powder (LS) in substitution of PC. Additional mixes were obtained by adding 1% of ‘Ambadi’ fibres weight (as a percentage of binder weight) to the same mix composition. Flexural and compressive tests were performed on mortar prisms to evaluate the peak strengths of all materials and the post-peak performance in flexure of fibre reinforced specimens. The study has revealed that mortar mixes with up to 90% replacement of PC can be successfully used in the construction industry to achieve mechanical performances sufficient for structural application. Such mixes are also demonstrated to be compatible with plant-based natural fibres, which have the potential to contribute to crack restraint and durability of concrete positively.
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