Strain Hardening Concrete – Applications in Underground Coal Mines

Who is Illinois Tool Works (ITW)? - ITW is a global, diversified manufacturer of engineered products - Established Financial performance Y11: revenue $17.8bn - Third largest patent holder in the US business units worldwide - ITW Construction Systems established manufacturing facilities in Australia

What is Strain-Hardening Concrete?  Strain hardening effect  High ductility  Micro cracking

Micro cracking  Micro cracking  Improved corrosion protection  No delamination What is Strain-Hardening Concrete?

 Portland Cement  Fly Ash  Water (w/c-ratio~0.35)  Sand (≤ 400 Micron)  Polyvinylalcohol (PVA) Fibres (2%)  Admixtures What is Strain-Hardening Concrete?

 Compressive Strength: 50 MPa  Flexural Stress (ultimate): 8 MPa  Tensile strength (ultimate): 5 MPa  Young’s Modulus: 17 GPa  Tensile Strain Capacity: > 1.5%  Crack width at Ultimate: < 0.3mm  Density: 200 kg/m 3 Flexus TM – Engineering Properties

Strain ε [%] Flexus TM – Typical Stress Strain Curves Strain ε [%] Tensile Stress [Mpa] Flexural Stress [Mpa]

Flexus TM – Applications in Underground Coal Mining  Ventilation Control Devices  Repair of Ventilation Control Devices  Rib Support

Flexus TM – Ventilation Control Devices  No rebate required  Material reduction of up to 25%  Significantly less rebound  Less transport and maintenance  Faster installation

Flexus TM – Repair of VCDs  High bond strength – no preparation required  Strain-hardening behaviour limits delamination  Micro-cracking keeps VCDs air tight even if seal deflects due to roof-to-floor conversion due to roof-to-floor conversion  Significantly less rebound  Less labour, transport and maintenance

 Flexus can be sprayed onto unprepared coal  Fast application speed (>50m 2 per hour)  Up to 3 times faster than conventional rib support  Up to 10 times faster in hard-to-get areas BeforeAfter Flexus TM – Rib Support

Flexus TM – Summary  Cost-efficient solutions due to less material required  Trained contractors available  Technical assistance  Product design can be tailored to specific requirements  Onsite support by trained representatives

ITW Construction Systems Claus Rotstein, Business Development Manager