Vane and triaxial strengths mobilised for sewage sludge 1 and a time to failure (t _f) of ∼ 12·5 min: (a) shear resistances of physically identical specimen pairs (adopted from O’Kelly (2013a)); (b) correlation between undrained strengths deduced for 38 mm dia. triaxial specimens, with 100 kPa cell pressure, and 12·7 mm dia. cruciform vane (adopted from O’Kelly (2013a))