DETERMINATION OF A LIMIT WATER/CEMENT RATIO AS A FUNCTION OF CEMENT, TO BE USED AS AN INDEX FOR EXPOSED CONCRETE

Details are given of a method for determining the viscosity of cement paste. Based on analyses of the viscosity of cement pastes varying in water/cement ratio, a viscosity curve can be plotted for each type of cement. It was shown that, in exposed concrete structures, the viscosity of the cement paste must not fall below a limit viscosity if the formation of filaments on the surface of the exposed concrete is to be avoided. This limit viscosity corresponds to a certain water/cement ratio which is defined as the limit water/cement ratio for exposed concrete. This limit ratio is not constant for all types of cement, but is an index which is a function of the cement and which must be determined for each cement before laying begins. Other possible applications of cement paste viscosity measurements are outlined. /IRRD/