Development of self-leveling screed based on calcium sulfoaluminate cement:: Modelling of curling due to drying

The development of cement-based screed unbound to its support is still limited because of the curling that occurs at the corners and perimeter of the screed. This phenomenon is mainly due to the moisture gradient that appears within the thickness of the screed: the upper surface dries and shrinks, whereas lower regions dry less and stay wetter. This paper demonstrates this phenomenon can be mitigated through the use of calcium sulfoaluminate cement instead of ordinary Portland cement. Experiments utilizing an original, specially designed device, show that curling is 3.5 times lower when calcium sulfoaluminate cement is used compared to ordinary Portland cement. The moisture gradient within the thickness of the screed is also lower. A model based on simplified poroelasticity theory describes both fluid transfer and hydro-mechanical coupling. The comparison between experimental and calculated results shows that the model gives a good estimation of the kinetics of the mass loss, and that the numerical simulation is an effective tool to predict curling due to drying. (C) 2008 Elsevier Ltd. All rights reserved.