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Abstract

This dissertation presents the experimental investigation of the combined use of metakaolin, ground granulated blast-furnace slag (GGBS) and fly ash as partial cement replacements in concrete. The investigation aims to create a concrete mix design that substantially reduces the percentage of Portland cement used; while maintaining sufficient compressive strength, durability and workability to develop a more sustainable mix. The workability of fresh concrete was tested through the slump test in accordance with BS EN 12350-2. The hardened concrete cubes were tested for compressive strength by crushing in accordance with BS EN 12390-3 after 28 days and 56 days. The density was measured at both stages according to BS EN 12390-7. The microstructure and chemical properties were analysed using scanning electron microscope (SEM), x-ray fluorescence (XRF), and x-ray diffraction analysis (XRD). These parameters were evaluated to assess the suitability of the new mix in industry.
Overall it was concluded that the three cement replacements: GGBS, fly ash and metakaolin work well together to produce a favourable concrete mix. Mix four, which contained 40% GGBS, 20% fly ash, 15% metakaolin and 25% cement, was the most practical in almost all categories, durability, compressive strength, sustainability and price. It was able to surpass the characteristic strength and achieve a compressive strength of 52.77 after 56 days. The mix also used 75% less cement than CEM 1 concrete. Thus a strong, sustainable concrete mix was developed.

Course: Civil Engineering - MEng - U0178178YC

Date Deposited: 2023-07-13

URI/permalink: https://library.port.ac.uk/dissert/dis14151.html