This work utilized the uni-directional freezing apparatus by Tao et al. (2004) to conduct the freezing tests of wastewater sludge floc. The wastewater floc was hung on an elastic beam which was subjected to constant-speed freezing. The deflection of the cantilevered beam was recorded at uni-directional freezing and thawing. Based on Hooke's law, the force exerted on the floc was estimated by the beam deflection.