Properties of high-strength lightweight concrete using manufactured aggregate

The physical and mechanical properties of high-strength lightweight concrete were investigated considering various parameters including mixture design proportions, dosages and types of superplasticiser and silica fume and cement content aiming at a design strength of 45 MPa. The experimental results of density, tensile strength, modulus of elasticity and efficiency factor (ratio of compressive strength to density) were compared with empirical equations previously proposed in the literature. In earlier studies, using expanded clay coarse aggregate of maximum size 25 mm, the lightweight concrete presented a maximum strength of 30 MPa and an efficiency factor of 18·9 MPa.dm3/kg. By reducing the maximum size to 9·5 mm, a higher compressive strength of approximately 46·9 MPa and an efficiency factor of 28·3 MPa.dm3/kg were obtained. However, using expanded shale coarse aggregate yielded higher values of compressive strength and efficiency factor at 64·3 MPa and 36·3 MPa.dm3/kg, respectively. The replacement of coarse expanded clay aggregate with expanded shale resulted in a high-strength lightweight aggregate concrete with the best properties in this study: fc28 = 64·3 MPa, a density of 1·77 kg/dm3 and an efficiency factor of 36·3 MPa.dm3/kg.