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Abstract

Industrial waste materials can be used as a partial cement replacement to reduce the carbon emissions of concrete. However, the addition of industrial waste materials especially at high replacement levels can increase the brittleness of concrete. As a result, fibre reinforcement can be an alternative solution to steel reinforcement to combat the increased brittleness due to cement replacement materials.

Steel fibres are commonly used in the construction industry, but steel fibres can be susceptible to rusting and may cause injuries to workers. To reduce the steel fibre content, Hybrid fibre reinforced concrete (HFRC) can be an effective solution without compromising the mechanical performance. Thus, considering macro polypropylene fibre advantages this study investigated the effect of different cement replacement materials (CRM) on the mechanical properties of macro polypropylene steel hybrid fibre reinforced concrete (HFRC).  

The hybrid fibre dosage combination in the HFRC consisted of 0.5% macro PPF and 0.25% steel fibre. Steel fibre reinforced concrete (SFRC) (0.5% fibre dosage) was also investigated in this study for comparison. The cement replacement material which was considered in the FRC mixes was pulverised fuel ash (PFA) (20% and 30% content) and ground granulated blast furnace slag (GBBS) (50% and 75% content). Concurrently in this study, the carbon emissions and the cost of the different mixes were also assessed. 

The experimental study revealed that SFRC without CRM performed well regarding mechanical properties compared to the other mixes but was the mix which resulted in the highest carbon emissions and cost. On the other hand, the HFRC with 75% GGBS performed the best in reducing carbon emissions and cost but performed poorly regarding the mechanical properties by exhibiting a significantly low strength. Nevertheless, from assessing the different mixes explored in this study, it was observed that adding steel fibres improved the flexural performance more than hybrid fibres. Furthermore, it was observed that hybrid fibres had an adverse effect than steel fibres on the workability especially in mixes with GGBS. As a result, it was concluded that steel fibre reinforced concrete with 50% GGBS was the mix which performed well overall in terms of both mechanical properties and sustainability aspects. As a result, SFRC with fibre dosage of 0.5% and 50% cement replaced with GGBS can be a viable sustainable FRC solution that can be adopted for civil engineering applications. 

Course: Civil Engineering - MSc - C0618

Date Deposited: 2025-01-20

URI/permalink: https://library.port.ac.uk/dissert/dis14691.html