Factors affecting the strength of structural lightweight aggregate concrete with and without fibers in the 1,200–1,600 kg/m³ density range

Concrete compressive strength decreases significantly with decreasing density and therefore, there are few examples of structural grade concretes with densities below 1,600 kg/m³. Here we show the development of structural lightweight aggregate concrete in the 1,200–1,600 kg/m³ density range. Compressive strengths of up to 36 MPa are obtained at 28 days. By using fibers, mixes with flexural strengths of up to 7 MPa and high ductility in flexure are obtained at 28 days. These results are significantly better than those in existing literature at comparable densities. Compressive strength of lightweight concrete depends on both paste and aggregate properties, while the flexural strength depends mostly on the volume fraction of fibers used.