The main objective of this project was to investigate the effect of adding polyethylene fibres to a clay mixture and to see the impact of the impurities in the fibres on the strength and the ductility.
From bending tests it was confirmed that the effect of the plastic fibres in a series of clay/gravel beam specimens was beneficial of both strength and ductility and showed a potential of further development towards a reliable building material. The impact of the fibres in a compression test revealed on the other hand that there was no significant effect by adding the plastic fibres and therefore, it would be an economical disadvantage to use the plastic fibres in compression elements. From the results it was also observed that the impact from the impurities in the fibres
was large. This was especially seen for the bending tests, were the strengths was significantly higher for the cleaned fibres except for a fibre content of 4%, whereas the impurities' impact on the toughness showed to be non beneficial up to a fibre content of 1.25%, but appeared to have a positive impact on the specimens with higher fibre contents than 1.25%. This result implies that the impurities have properties which leads to a higher ductility when using a high fibre content and therefore the impurities may not be a disadvantage, when designing a structure, where a high plasticity is wanted. For the compression test there was no clear impact of the impurities, and for this reason there is no need for cleaning the fibres or in general to use fibres when designing a
compression element with these materials.
It can be concluded that the reinforced plastic fibre clay elements has a potential as a
zerowaste construction material, but further investigations have to be made in order to
have a reliable building material with suffcient strengths and ductility.
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