Periodic Reporting for period 1 - FireCracker (Reuse of Waste Materials for Fire-Spalling-Proof and Crack-Resistant Sustainable Concrete)
Reporting period: 2017-09-01 to 2019-08-31
Currently, there are no guaranteed preventative measures or design specifications to completely control shrinkage cracking and fire-induced spalling. Eurocode 2 (EC2) and some engineers suggest that polypropylene fibres (PPF) can be used in high-performance concrete to control early-age plastic shrinkage cracking and prevent explosive fire-induced spalling. Although the minimum dosage of PPF (e.g. 0.9-1.0 kg/m3 for plastic shrinkage control, and 2-7 kg/m3 for fire-induced spalling) is often prescribed or recommended, essential guidance (e.g. fibre type, length, diameter) on how to use PPF is still missing. Moreover, given the non-sustainable nature of petroleum derived PPF, it is proposed to replace these PPF by waste polymer fibres recovered from end-of-life tyres, fabrics, bed mattresses, and similar. The repurposing of waste polymer fibres in concrete will not only provide waste management solutions, but also deliver a more environmental-friendly cracking/spalling-mitigation solution.
The main objective of this project are to develop a better understanding of the complex mechanism behind shrinkage cracking and fire-induced spalling of concrete and to develop novel sustainable spalling-proof and crack-resistant concrete using waste polymer fibres (to replace polypropylene solutions) and greener cementitious materials. In the work conducted so far, the polymer fibres derived from the recycling of end-of-life tyres were explored as the potential alternative to virgin polypropylene fibres (PPF) to mitigate plastic shrinkage cracking in concrete. Recycled Tyre Polymer Fibres (RTPF), which originally contain a significant amount of rubber contamination, were cleaned and characterized using multi-techniques. The plastic shrinkage cracking susceptibility of Portland cement concrete with various mix proportions and fibre dosage/types was evaluated following ASTM C1579. Preliminary experimental results confirm the RTPF’s potential of reducing the crack width of concrete, depending on the mix proportion and fibre dosage.