Quantification of the water demand of sand in mortar

The sand type has an important influence on the properties of mortar. By means of an extensive experimental research programme. considering nine different sand types, this influence is characterised and quantified. Two series of mortar tests have been undertaken. A first series with a standard mortar composition, and a second series with a modified composition (by changing the sand cement factor) in order to obtain a certain target value for the workability. The results show a very significant influence of the sand type on the mortar properties, with important consequences regarding mix design. The water demand related with the different sand types is investigated considering some geometric sand properties like fineness modulus, relative specific surface and fictitious weight. However, a better correlation is obtained with the apparent dry density or bulk density of the sand. The apparent dry density proves to be a very important parameter for the estimation of the water demand of the sand as well as for the influence of the sand type on the rheological and strength properties of the mortar. (C) 2004 Elsevier Ltd. All rights reserved.