Abstract:

This paper presents part of the results of an ongoing laboratory study carried out to design a structural lightweight high strength concrete (SLWHSC) made with and without ternary mixtures of cement-fly ash-silica fume. In the mixtures, lightweight basaltic-pumice (scoria) aggregate was used. A concrete mixture made with lightweight scoria, and another lightweight scoria concrete mixture incorporating 20% fly ash and 10% silica fume as a cement replacement, were prepared. Two normal weight concretes were also prepared for comparison purposes. The 28 day compressive strength and air dry unit weight of structural lightweight concrete (SLWC) varied from 28 to 37 MPa and 1800 to 1860 kg/m3, respectively. Laboratory test results showed that structural lightweight concrete SLWC of 30 MPa at 28 days can be produced by the use of scoria. However, the use of mineral additives seems to be mandatory for the production of SLWHSC of 35 MPa or higher grade.

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