Paper by SPRINGENSCHMID VOGEL from ISCR 8th 1998 Lisbon Portugal
The natural raw materials gravel and sand are worldwide mined on a large scale. In many areas of Germany natural resources contain 70 % (and more) sand and less than 30 % gravel. Therefore in particular very fine sand often cannot be used and must be stored in waste disposal sites. For economic and ecological reasons it would be helpful to use sand-rich concrete. Sand-rich concrete is a mixture of cement, filler, water and up to 80 % sand and 20 % coarse aggregate. The filler is pozzolanic (fly ash) and its fineness is at least of the same, or higher, than that of the cement. The Portland cement content (CEM 132,5 R) does not differ greatly from the cement content of ordinary concrete. This new technology can only be developed since very efficient super-plasticizers are available and the water content required for a suitable workability can be reduced. Sand-rich concrete is already used in some areas of Germany - up to now only for interior construction members. It is possible to reach a good workability and a cube strength class B 25 (more than 30 N/mm 2). The compressive and tensile strength, Youngs modulus, water permeability, shrinkage and swelling and resistance to frost and deicing chemicals of sand-rich concrete pavement were investigated. These technical data are used for the selection of the concrete mix and the pavcmcnt design.