Development and prospectives of lightweight high strength concrete using lightweight aggregates

Lightweight high strength concrete (LWHSC), which combines the properties of both lightweight concrete (LWC) and high strength concrete (HSC), is gaining popularity due to its increased strength and reduced self-weight, that are easier to handle and provide economic benefits. However, LWHSC is particularly sensitive to its material constituents and pose unique characteristics to apply in real practice. To holistically comprehend the material characteristics of LWHSC and to aid in developing a mix design guideline, a thorough appraisal of the characterisation of LWHSC was carried out in this study. In total, 197 LWHSC mixes with oven dry densities of less than 2000 kg/m³ and 28-day compressive strengths of greater than 60 MPa were gathered from previous studies for the appraisal. The constitutive materials used, alongside the effect of them on the key properties of LWHSC such as density, workability, compressive strength, splitting tensile strength, flexural strength, and modulus elasticity were evaluated. It was found that the mechanical properties of LWHSC can be greatly enhanced by strategically choosing the types and amount of binder, water to binder (w/b) ratio, fibres, and the lightweight aggregate (LWA) which is influenced by its particle size, crushing strength, water absorption, and porosity. Using the database established, it was discovered that the existing correlations used to assess the mechanical properties of conventional concrete needed to be revised for LWHSC. This study intends to facilitate researchers in exploring more about LWHSC in the future with the knowledge gaps identified from this review study, as well as associated construction practitioners in producing LWHSC.