Effect of lightweight aggregate intrinsic Strength on lightweight concrete compressive strength and modulus of elasticity

Abstract

The study of Structural Lightweight Concrete (SLC), which is a material generally composed of cement, water and lightweight aggregate, has been mainly focused on developing particular cases. Then, the main objective of this research was to generalise the knowledge of this type of material. Particularly, the effect of replacing conventional coarse aggregate by lightweight aggregate on mechanical properties of concrete was studied. SLC may be conceived as a two -phase material. The first phase, composed of cement, water and siliceous natural sand, is called the "resistant phase", and contributes to the structural strength. The second phase is the lightweight phase, comprised of coarse lightweight aggregate, and it is meant to decrease the concrete density. In this way it would be possible to describe the mechanical behaviour of concrete, based on lightweight aggregate and the cement mortar parameters. The obtained results allow for the proposition of relationships between mechanical properties of SLC (such as compressive strength and modulus of elasticity) and the constituent materials properties and amount. At the same time, an easily measured index representing the structural capability of lightweight aggregate is also proposed, this index allows to estimate the potential mechanical properties of concrete which could be obtained by using a particular aggregate.