Key Objectives

To explore new and develop previously tested applications for RTSF in concrete and develop suitable design guidelines for rapid adoption by the construction industry.

To develop innovative applications using well sorted waste steel from tyres as well as fibre blends, creating high end value products by fully utilising the strength and significantly improved environmental profile of RTSF in concrete.

WP3

Task 3.1: Fibre blends for shrinkage control and structural applications

To determine the blends with the optimum mechanical characteristics (defined in WP1) wet concrete mixes will be developed (for the first time) using different amounts of manufactured (M) and sorted RTSF fibres. New tests will be developed (Figure right) to study the effect of both restrained shrinkage and auto-healing on the flexural properties (Modulus of rupture, residual strength and Modulus of Elasticity).

Task 3.2: Pumpable and self compacted concrete and mortar

For speed and ease of application, much of today’s concrete is pumped to place. Suitable concrete and mortar SFRC mixes with RTSF and fibre blends will be developed, with emphasis on the fresh properties of concrete. These mixes will have enough mortar, sufficient amount of fines, optimum fibre dosage and will demonstrate high enough slump to ensure good pumpability.

Task 3.3: Precast concrete elements

The technologies developed in Task 3.2, will also be suitable for precast concrete elements. An additional problem encountered in elements cast in thin closed moulds, is the directionality of the fibres due to flow and boundary conditions. Simple tests will be developed to examine these effects using moulds supplied by the industrial partners, and in conjunction with the findings of Task 3.1 on fibre orientation.

Task 3.4: Sprayed concrete

Proof of concept studies by the proposers showed that RTSF can be easily included in sprayed concrete even at high fibre dosages (up to 100kg/m3) with no fibre agglomeration issues. However, it was also found that the mix designs need optimisation and fibre blends to be examined. Furthermore it was concluded that further studies are required to assess the effect of the spraying process on the mechanical properties of SFR sprayed concrete as well as examine durability (Task 3.7) and crack control.

Task 3.5: Screeds

RTSF 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. control.

Task 3.6: Slurry infiltrated concrete

Proof of concept studies undertaken by the proposers revealed the suitability of RTSF in security applications. SIFCON containing 600kg/m3 of RTSF were tested against 0.6kg high explosives.The performance of these slabs was similar to that seen in previous studies at USFD on similar sized panels with steel back-plate reinforcement. A more detailed experimental parametric study of the panels is required to better identify the load-response characteristics of the panels.

Task 3.7: Durability studies

Additional properties, beyond mechanical are durability properties and mechanical properties after exposure to aggressive environments. Additional evaluation of the durability properties for selected mixtures will be obtained by comparing the performance in laboratory testing and in real environment through demonstration projects in WP5.

Task 3.8: Design Guidelines and Examples

By using the experience from WP1 and Tasks 3.1 – 3.7, practical guidelines and examples will be developed to enable engineers to design slabs on grade, suspended slabs, screeds, precast concrete elements, SIFCON and spay concrete. The guidelines will include information on material properties and recommended safety factors.