Properties of Self-leveling Concrete: Influence of a Viscosity Agent and Cement Content

This paper deals with the development of self-levelling concrete at low cost for casting slabs and other horizontal structures. The 28-day compressive strength of such concrete is in the range of 25 to 40 MPa, and its cost is 15% higher than that of usual concrete. This overcost is offset by some advantages: quicker execution, absence of noisy vibration at job-site and reduced painful task for workers. The cement content for this concrete ranges from 260 to 380 kg/m3, and that of limestone powder form 20 to 140 kg/m3, in order to get a total amount of fine particles of 400 kg/m3. To prevent segregation, a viscosity agent - a suspension of modified starch - was introduced in the mixture at different contents. The following characteristics were measured: static spread of concrete, unit weight, bleeding, resistance to segregation, compressive strength, elastic modulus and shrinkage. The results show that the optimum dosage of viscosity agent is 2 kg/m3, regardless of the amount of cement.