WP4 will aim to find for the first time a use for RTPF in concrete. The main challenges other than cleaning the RTPF are the introduction the fibres into concrete mixes and identification of suitable applications.
To develop for the first time fibre reinforced concrete mixes reusing waste polymer fibres (developed in WP1) from post-consumer tyres to enhance resistance to shrinkage cracks.
To explore and identify suitable applications for RTPF in concrete and to put an end to the current practice of landfilling this material. Both mixes with RTPF and blends with RTSF and manufactured fibres will be investigated.
Task 4.1: RTPF reinforced concrete
Preliminary (very limited) research performed by the proposers, showed that the main benefit from adding RTPF in concrete is the control of shrinkage cracking (especially plastic) as well as a decrease in permeability. To confirm and extend these preliminary findings this task will investigate a variety of mixes with RTPF as well as blends with RTPF, RTSF and manufactured (M) fibres (identified in Task 3.1 of WP3).
Task 4.2: RTPF Sprayed concrete
RTPF due to its size and flexibility it is expected to benefit sprayed concrete by minimising rebound and increasing toughness. To confirm this testing will be made on in-situ prepared specimens (similar to those in the Figure on the left) and will be extended to extraction of cores for tests assessing the compressive strength, flexural strength, energy absorption.
Task 4.3: Screeds
RTPF reinforced screeds will be developed for overlays on new or damaged concrete surfaces. These overlays will be tough, with low shrinkage potential and suitable surface characteristics as well as good adhesion to the base layer.
Task 4.4: Durability studies
Previous research performed by the proposers showed that the incorporation of RTPF in concrete/mortar could reduce permeability and this will be confirmed by a series of water permeability tests. Other aspects of durability will also be investigated with tests on capillary absorption, chloride diffusion and freeze-thaw resistance. Finally resistance to accidental fire will be studied in terms of residual compressive strength, flexural strength and modulus of elasticity on preloaded elements to include the phenomenon of transient strain.
Task 4.5: Physical Model, design guidelines and examples
By using the experience from all previous sub work packages,a physical model will be developed to take into account the effect of fibres on the behaviour of cracked concrete. This model will be calibrated against the experimental results obtained from literature and results obtained in Task 4.1.